bdj of endo_2005

BRITISH DENTAL JOURNAL VOLUME 197 NO. 4 AUGUST 28 2004 179

PRACTICE

Endodontics — a series overviewP. Carrotte1

1*Clinical Lecturer, Department of AdultDental Care, Glasgow Dental Hospital andSchool, 378 Sauchiehall Street, Glasgow G2 3JZ*Correspondence to: Peter CarrotteEmail: [email protected]

Refereed Paperdoi:10.1038/sj.bdj.4811582© British Dental Journal 2004; 197:179

Stock and Nehammer's BDJ textbook Endodontics in Practice was first published in1985, and almost immediately became a standard text for both undergraduate studentsand general practitioners. In the first sentence of the first chapter the authors observed‘during the last three decades research in the field of endodontics has modified theapproach to treatment’, and that observation was retained in the extensively revisedsecond edition, published in 1990.

With an inordinate amount of research of an increasingly high standard takingplace, the changes in the field of endodontics during the last decade have been evengreater, and a third edition was required to keep practitioners up to date with currentthinking and practice. Sadly, because of their research and other commitments, ChrisStock and Carl Nehammer did not have the time to devote to such a task, and I amtherefore honoured and delighted to have edited this edition of their text and convertedit to the new BDJ Clinical Guide format.

In some aspects of the subject there has been little change, whilst the developmentsin others have been immense. I may be criticised for retaining some historical materialwhich could seem outdated to the modern practitioner using the latest canalpreparation techniques. However, few dental schools have the resources necessary tointroduce many of the recent developments, and undergraduate students still learnconventional techniques. It is important that they understand how these havedeveloped, and it is essential, as with most things in life, that they develop basic skillsbefore advanced ones!

The subject is covered in 12 parts. The first part emphasises the modern concept ofendodontics, surprisingly founded upon research published almost forty years ago. Root canal treatment must be seen as essentially the treatment of a disease process.The procedures must both remove all infection from the root canal system, andprevent contamination by other pathogenic organisms. Failure to achieve either ofthese aspects may compromise success and lead to eventual failure. Parts 2 and 3consider the importance of diagnosis in treatment planning, and how emergencyevents may be quickly diagnosed and treated. Part 4 shows how research into rootcanal morphology continues, knowledge of which is essential for effective shapingand cleaning.

Parts 5 to 9 cover the technical procedures, but the wise reader will realise thatthere is no ‘best way' to clean, shape and obturate a tooth. Various manufacturers makeclaims that their own product is the latest and best. The emphasis in the series is theunderstanding of the objectives of treatment. The actual technical procedures must besecondary to this. Dentists are clinicians, not technicians, and should use whicheverprocedure works best in their own hands to resolve the diagnosed disease process.‘Step-back and apical stops’ may be old-fashioned, one brand of rotary instrumentsmay have been around longer than another, but if the technique works for you thenwhy change it?

As in Stock and Nehammer's original text, the final three parts of the seriesconsider some wider aspects of endodontic treatment. These subjects are not consideredin great detail, but hopefully direct readers to deeper study of the subjects concerned intexts dedicated to that specific aspect.

However, it is hoped that readers will consider this is a practical series written forthe practice of endodontics. The research which underpins this practice is discussedwhere necessary, but the prime aim of the series is to guide practitioners through theireveryday treatment of teeth with endodontic problems.

ENDODONTICS1. The modern concept of

root canal treatment2. Diagnosis and treatment

planning3. Treatment of endodontic

emergencies4. Morphology of the root

canal system5. Basic instruments and

materials for root canaltreatment

6. Rubber dam and accessactivities

7. Preparing the root canal8. Filling the root canal

system9. Calcium hydroxide, root

resorption, endo-periolesions

10. Endodontic treatment forchildren

11. Surgical endodontics12. Endodontic problems

● An overview of the new 12-part BDJ series on Endodontics.

I N B R I E F

04p179.qxd 29/07/2004 17:27 79

norms

Text Box

http://dentalbooks-drbassam.blogspot.com/

PRACTICE


Endodontics: Part 1The modern concept of root canal treatmentP. Carrotte1

Root canal treatment has changed considerably since the hollow tube theory was first postulated in 1930. Research continuesinto the elaborate anatomy of root canal systems, and also into the microbial causes of endodontically related diseases. Only byunderstanding these aspects in detail can the practitioner quickly and effectively shape the main root canals to facilitatethorough cleaning of the entire system, and easy and effective filling.

● Root canal treatment is normally prescribed to treat an infection, and as with all surgicalprocedures an aseptic technique is essential throughout.

● As research has shown that success is only achieved when all microorganisms are removedfrom the entire root canal system, the anatomy of this system must be understood for eachtooth.

● Modern endodontic practice is concerned not with the old cliché of cleaning, shaping andfilling, but with shaping first, to open the canals wide, so that cleaning can be effectivelycarried out prior to three-dimensional filling.

I N B R I E F

In 1965 Kakehashi, Stanley and Fitzgerald1

showed conclusively that pulpal and endodonticproblems are primarily related to microbial con-tamination of the root canal system. Since thattime endodontology has increasingly focussedon the ways and means of eliminating micro-organisms from the entire root canal system.

The majority of patients who require rootcanal treatment will have been diagnosed as suf-fering from the disease of periradicular peri-odontitis. The treatment of this disease mustaddress the microbial contamination of theentire root canal system. It must also be carriedout under aseptic conditions in order to preventfurther microbial ingress, in particular from saliva.The use of a rubber dam very much reflects theuse of a surgical drape in other invasive medicalprocedures. Such a biological approach will beemphasized throughout this text. The temptationto regard root canal treatment as a purelymechanical procedure, producing excellentpost-operative radiographs but with little regardto diagnosis and prognosis, must be resisted intoday�s practice.

Research into the morphology of the pulp hasshown the wide variety of shapes, and the occur-rence of two or even three canals in a singleroot.2 There is a high incidence of fins which runlongitudinally within the wall of the canal and anetwork of communications between canalslying within the same root (Fig. 1). The manynooks and crannies within the root canal systemmake it impossible for any known technique,either chemical or mechanical, to render it total-ly sterile. The objective of treatment must be to

reduce the level of microbial contamination asfar as is practical, and to entomb any remainingmicroorganisms with an effective three-dimen-sional seal.

The prime aim when preparing the root canalhas long been stated as cleaning and shaping.One of the prime aims of this text will be toencourage the practitioner to see this inreverse, ie shaping and cleaning. Moderninstruments and techniques will be describedwhich rapidly open and shape the main root

1







6. Rubber dam and accesscavities






Fig. 1 The rootcanal system ofthis lower molarhas been stainedand the toothtotally decalcified,showing thecomplex nature ofthe root canalsystem. (Courtesyof Professor R TWalker.)


Refereed Paperdoi:10.1038/sj.bdj.4811565© British Dental Journal 2004; 197:181–183

VERIFIABLE CPD PAPER

NOW AVAILABLE AS A BDJ BOOK

04p181-183.qxd 26/07/2004 15:09 Page 181

norms

Text Box


PRACTICE

182 BRITISH DENTAL JOURNAL VOLUME 197 NO. 4 AUGUST 28 2004

canals, thus permitting the effective access ofantimicrobial irrigants to the entire root canalsystem, including lateral canals, fins, anasta-moses and other canal aberrations. It is imper-ative that these instruments are not seen asproviding a route to quick and speedy rootcanal treatment. To achieve success the timesaved by the rapid opening of the canal systemmust be spent in thorough and effectiveantimicrobial irrigation.

Research has also shown that when an infect-ed root canal is accessed, the number of differentspecies of microorganisms is small, rarely abovesingle figures.3 Treatment will become far moredifficult and extended, and success may well becompromised, if this flora is altered by theingress of saliva. Isolation of the tooth undertreatment is essential not only for medicolegalreasons to protect the airway, but, far moreimportantly, to prevent further contamination ofthe root canal system and to permit the use ofstrong intracanal medicaments.

Other areas of research have had the signifi-cant effect of changing the approach toendodontic treatment. The hollow tube theoryput forward by Rickert and Dixon in 19314

postulated that tissue fluids entering the rootcanal stagnated and formed toxic breakdownproducts which then passed out into the peri-apical tissues. This theory, that dead spaceswithin the body must be obturated, originallyformed the basis for filling root canals. How-ever, a variety of different studies havedemonstrated that, on the contrary, hollowtubes are tolerated by the body. As a resultthere are currently two indications for filling aroot canal, once the canal system has beenshaped and cleaned. Firstly, to prevent theentry of microorganisms to the root canal sys-tem from either the oral cavity, should thecoronal restoration leak or fail, or via thebloodstream (anachoresis). Secondly, to pre-vent the ingress of tissue fluid which wouldprovide a culture medium for any bacteriaremaining within the tooth following treatment.

A report by Klevant and Eggink5 is particular-ly relevant. They shaped and cleaned a number

of root canals, but the experimental group werenot obturated. They ensured that an effective,well-sealed, coronal restoration was placed.They found that healing occurred in every case.Figure 2 shows a lower molar with a large peri-radicular lesion. The root canal system wasshaped and cleaned, and an intervisit dressing ofcalcium hydroxide placed. The patient did notreturn for further treatment for 6 months, when aradiograph revealed that complete healing hadtaken place.

Of course, this does not mean that obturation isunimportant. It is essential for the reasonsdescribed earlier. It does prove, however, the oldcliché that it is what is removed from the canalthat is important, not what is put in. Similarly,Ray and Trope6 found that root-treated teeth witha poor obturation on radiograph but a good coro-nal restoration had a better prognosis than teethwith a good obturation but a poor restoration.

The majority of root canal sealers are solubleand their only function is to fill the minutespaces between the wall of the root canal and theroot filling material. Their importance, judgedby the number of products advertised in the den-tal press, has been over-emphasized. Despitemuch research, gutta-percha remains the rootfilling of choice, although it is recognized that abiologically inert, insoluble and injectable pastemay be better suited for obturation of the rootcanal. Most of the new root canal filling tech-niques are concerned with methods of heatinggutta-percha, making it softer and easier toadapt to the irregular shape of the canal wall. Itmust be emphasized, however, that, whateverthe obturation system used, if the root canal sys-tem has not been adequately cleaned healingmay not occur (Fig. 3).

Finally, lesions of endodontic origin whichappear radiographically as areas of radiolucencyaround the apices or lateral aspects of the rootsof teeth are, in the majority of cases, sterile.7,8

The lesions are the result of toxins produced bymicroorganisms lying within the root canal sys-tem. This finding suggests that the removal ofmicroorganisms from the root canal followed byroot filling is the first treatment of choice, and

Fig. 2 (a) The pre-operative radiograph of tooth LR6 (46) shows a largeradiolucent area associated with the root apex and the furcation area. Rootcanal treatment was commenced. (b) A radiograph 6 months later when

the patient finally returned to continue treatment shows evidence of bonyrepair with a return to a normal periodontal ligament space around theapex and in the furcation.

a b

04p181-183.qxd 26/07/2004 15:11 Page 182

PRACTICE


that periradicular surgery, including an apicec-tomy with a retrograde filling, can only be sec-ond best.9 Apicectomy with a retrograde fillingat the apex is carried out in the hope of merelyincarcerating microorganisms within the tooth,but does not take into account the fact thatapproximately 50% of teeth have at least onelateral canal. The long-term success rate ofapicectomy must inevitably be lower thanorthograde root treatment.

In summary, the principles of treatment of thedisease of periapical periodontitis are as follows.Shape: Produce a gradual smooth taper in the

root canal with its widest part coronallyand the narrowest part at the apicalconstriction, which, as discussed in Part 4, is normally about 1 mm short ofthe apex.

Clean: Use antimicrobial agents to removemicroorganisms and pulpal debris fromthe entire root canal system.

Fill: Obturate the canal system with an inert,insoluble filling material.

1. Kakehashi S, Stanley H R, Fitzgerald R. The effects ofsurgical exposures of dental pulps in germfree andconventional laboratory rats. J South California DentAssoc 1966; 334: 449�451.

2. Burns R C, Herbranson E J. Tooth Morphology andCavity Preparation, Chapter 7 in Cohen S and BurnsR C, Pathways of the Pulp, St Louis 2002: Mosby.

3. Molven S, Olsen I, Kerekes K. Scanning electronmicroscopy of bacteria in endodontically treated teeth.III In vivo study. J Endod 1991; 7: 226�229.

4. Rickert U G, Dixon C M. The controlling of rootsurgery. In Transactions of the Eighth InternationalDental Congress. Section 111a p15. Paris, 1931.

5. Klevant F J, Eggink C O. The effect of canal preparationon periapical disease. Int Endod J 1983; 16: 68�75.

6. Ray H A, Trope M. Periapical status of endodonticallytreated teeth in relation to the technical quality of theroot filling and the coronal restoration. Int Endod J1995; 28: 12�18.

7. Grossman L I. Bacteriologic status of periapical tissuein 150 cases of infected pulpless teeth. J Endod (SpecialIssue) 1982; 8: 513�515.

8. Siqueira J F, Lopes H P. Bacteria on the apical rootsurfaces of untreated teeth with periradicular lesions: a scanning electron microscopy study. Int Endod J2001; 34: 216�220.

9. Pitt Ford T R. Surgical treatment of apicalperiodontitis. Chapter12 in Ørstavik D and Pitt FordT R, Essential Endodontology. Oxford 1998: Blackwell.

Fig. 3 A radiograph of tooth LL7(37) showing a root canaltreatment carried out 12 monthspreviously, with what appears to bean effective obturation yet noevidence of healing of theperiradicular lesion.

British Dental Journal, July 1904Letter to the Editor

FFlluuoorriinnee iinn FFooooddSir,

No doubt after our Annual General Meeting you will be dealing with fluorine. It is my conviction that fluorineshould be given to children in the natural foodstuffs such as unrefined cereals, sea foods and cod liver oil, etc.Yesterday I saw an 11-month baby chewing and enjoying raw carrot. A short time ago I saw a girl of 16 broughtup on Hovis toast from the age of 12 months with excellent teeth.

The fluorine should be ingested at weaning time and onwards. Adding fluorine to drinking water may do a lit-tle good but it is very doubtful if it is of permanent value. I preach the building up of the atomic structure.

C.N. PeacockBr Dent J 1904

One Hundred Years Ago

04p181-183.qxd 26/07/2004 17:50 Page 183

shilpa

Rectangle

Endodontics: Part 2Diagnosis and treatment planningP. Carrotte1

As with all dental treatment, a detailed treatment plan can only be drawn up when a correct and accurate diagnosis has beenmade. It is essential that a full medical, dental and demographic history be obtained, together with a thorough extra-oral andintra-oral examination. This part considers the classification of diseases of the dental pulp, together with various diagnosticaids to help in determining which condition is present, and the appropriate therapy.

● An accurate diagnosis of the patient�s condition is essential before an appropriate treatmentplan can be formulated for that individual.

● A logical approach to clinical examination should be adopted.● A high quality long-cone parallel radiograph is mandatory before commencing root canal

treatment, and should be carefully examined to obtain all possible information.● Root canal treatment may not be the most appropriate therapy, and treatment plans should

take into account not only the expected prognosis but also the patient�s dental condition,expectations and wishes.

I N B R I E F

The importance of correct diagnosis and treat-ment planning must not be underestimated.There are many causes of facial pain and the dif-ferential diagnosis can be both difficult anddemanding. All the relevant information must becollected; this includes a case history and theresults of both a clinical examination and diag-nostic tests. The practitioner should be fullyconversant with the prognosis for differentendodontic clinical situations, discussed inPart 12. Only at this stage can the cause of theproblem be determined, a diagnosis made, theappropriate treatments discussed with the patientand informed or valid consent obtained.

CASE HISTORYThe purpose of a case history is to discoverwhether the patient has any general or local con-dition that might alter the normal course oftreatment. As with all courses of treatment, acomprehensive demographic, medical and previ-ous dental history should be recorded. In addi-tion, a description of the patient’s symptoms inhis or her own words and a history of relevantdental treatment should be noted.

Medical historyThere are no medical conditions which specifi-cally contra-indicate endodontic treatment, butthere are several which require special care. Themost relevant conditions are allergies, bleedingtendencies, cardiac disease, immune defects orpatients taking drugs acting on the endocrine orCNS system. If there is any doubt about the stateof health of a patient, his/her general medical

practitioner should be consulted before anyendodontic treatment is commenced. This alsoapplies if the patient is on medication, such ascorticosteroids or an anticoagulant. An exampleof the particulars required on a patient’s folder isillustrated in Table 1.

Antibiotic cover has been recommended forcertain medical conditions, depending upon thecomplexity of the procedure and the degree ofbacteraemia expected, but the type of antibioticand the dosage are under continual review anddental practitioners should be aware of currentopinion. The latest available edition of the DentalPractitioners’ Formulary1 should be consulted forthe current recommended antibiotic regime.However, when treating patients who may beconsidered predisposed to endocarditis, it may beadvisable to liaise with the patient’s cardiac

2













Table 1 A simple check list for a medical history(Scully and Cawson2)

Anaemia

Bleeding disorders

Cardiorespiratory disorders

Drug treatment and allergies

Endocrine disease

Fits and faints

Gastrointestinal disorders

Hospital admissions and attendances

Infections

Jaundice or liver disease

Kidney disease

Likelihood of pregnancy or pregnancy itself

PRACTICE





BRITISH DENTAL JOURNAL VOLUME 197 NO. 5 SEPTEMBER 11 2004 231

05p231-238.qxd 12/08/2004 11:51 Page 231

norms

Text Box


specialist or general medical practitioner. Not allpatients with cardiac lesions require antibioticprophylaxis, and such regimes are not generallysupported by the literature.2 However, if it isagreed that the patient is at risk, they would nor-mally be prescribed the appropriate prophylacticantibiotic regime, and should be advised toreport even a minor febrile illness which occursup to 2 months following root canal treatment.Prior to endodontic surgery, it is useful to pre-scribe aqueous chlorhexidine (2%) mouthwash.

Patient�s complaintsListening carefully to the patient’s descriptionof his/her symptoms can provide invaluableinformation. It is quicker and more efficient toask patients specific, but not leading, ques-tions about their pain. Examples of the type ofquestions which may be asked are givenbelow.1. How long have you had the pain?2. Do you know which tooth it is?3. What initiates the pain?4. How would you describe the pain?

Sharp or dullThrobbingMild or severeLocalised or radiating

5. How long does the pain last?6. Does it hurt most during the day or night?7. Does anything relieve the pain?

It is usually possible to decide, as a result ofquestioning the patient, whether the pain is ofpulpal, periapical or periodontal origin, or if it isnon-dental in origin. As it is not possible todiagnose the histological state of the pulp fromthe clinical signs and symptoms, the terms acuteand chronic pulpitis are not appropriate. In casesof pulpitis, the decision the operator must makeis whether the pulpal inflammation is reversible,in which case it may be treated conservatively,or irreversible, in which case either the pulp orthe tooth must be removed, depending upon thepatient’s wishes.

If symptoms arise spontaneously, withoutstimulus, or continue for more than a few sec-onds after a stimulus is withdrawn, the pulp maybe deemed to be irreversibly damaged. Applica-tions of sedative dressings may relieve the pain,but the pulp will continue to die until root canaltreatment becomes necessary. This may thenprove more difficult if either the root canalshave become infected or if sclerosis of the rootcanal system has occurred. The correct diagno-sis, once made, must be adhered to with theappropriate treatment.

In early pulpitis the patient often cannotlocalise the pain to a particular tooth or jawbecause the pulp does not contain any proprio-ceptive nerve endings. As the disease advancesand the periapical region becomes involved, thetooth will become tender and the proprioceptivenerve endings in the periodontal ligament arestimulated.

CLINICAL EXAMINATIONA clinical examination of the patient is carriedout after the case history has been completed.The temptation to start treatment on a toothwithout examining the remaining dentition mustbe resisted. Problems must not be dealt with inisolation and any treatment plan should take theentire mouth and the patient’s general medicalcondition and attitude into consideration.

Extra-oral examinationThe patient’s face and neck are examined andany swelling, tender areas, lymphadenopathy, orextra-oral sinuses noted, as shown in Figure 1.

Intra-oral examinationAn assessment of the patient’s general dentalstate is made, noting in particular the followingaspects (Fig. 2).• Standard of oral hygiene.• Amount and quality of restorative work.• Prevalence of caries.• Missing and unopposed teeth.• General periodontal condition.• Presence of soft or hard swellings.• Presence of any sinus tracts.• Discoloured teeth.• Tooth wear and facets.

Diagnostic testsMost of the diagnostic tests used to assess thestate of the pulp and periapical tissues are

Fig. 1 A facial sinusassociated with asevere periapicalabscess on the uppercanine.

Fig. 2 An assessmentshould be made of thepatient�s generaldental condition.

232 BRITISH DENTAL JOURNAL VOLUME 197 NO. 5 SEPTEMBER 11 2004

PRACTICE

05p231-238.qxd 12/08/2004 11:54 Page 232

relatively crude and unreliable. No single test,however positive the result, is sufficient to make afirm diagnosis of reversible or irreversible pulpi-tis. There is a general rule that before drilling intoa pulp chamber there should be two independentpositive diagnostic tests. An example would be atooth not responding to the electric pulp testerand tender to percussion.

PalpationThe tissues overlying the apices of any suspectteeth are palpated to locate tender areas. The siteand size of any soft or hard swellings are notedand examined for fluctuation and crepitus.

PercussionGentle tapping with a finger both laterally andvertically on a tooth is sufficient to elicit any ten-derness. It is not necessary to strike the tooth witha mirror handle, as this invites a false-positive reaction from the patient.

MobilityThe mobility of a tooth is tested by placing a fin-ger on either side of the crown and pushing withone finger while assessing any movement withthe other. Mobility may be graded as: 1 — slight (normal)2 — moderate3 — extensive movement in a lateral or

mesiodistal direction combined with avertical displacement in the alveolus.

RadiographyIn all endodontic cases, a good intra-oral paral-lel radiograph of the root and periapical regionis mandatory. Radiography is the most reliableof all the diagnostic tests and provides the mostvaluable information. However, it must beemphasised that a poor quality radiograph notonly fails to yield diagnostic information, butalso, and more seriously, causes unnecessaryradiation of the patient. The use of film holders,recommended by the National RadiographicGuidelines3 and illustrated in Part 4, has two dis-tinct advantages. Firstly a true image of thetooth, its length and anatomical features, isobtained (Fig. 3), and, secondly, subsequentfilms taken with the same holder can be moreaccurately compared, particularly at subsequentreview when assessing the degree of healing of aperiradicular lesion.

A radiograph may be the first indication of thepresence of pathology (Fig. 4). A disadvantage ofthe use of radiography in diagnosis, however,can be that the early stages of pulpitis are notnormally evident on the radiograph.

If a sinus is present and patent, a small-sized(about #40) gutta-percha point should beinserted and threaded, by rolling gentlybetween the fingers, as far along the sinus tractas possible. If a radiograph is taken with thegutta-percha point in place, it will lead to anarea of bone loss showing the cause of theproblem (Fig. 5).

Fig. 3 The anatomical detailobtained from a radiograph taken bythe long-cone paralleling technique(a) is far clearer and more accuratethan when the bisecting angletechnique (b) is used.

a b

Fig. 4 A radiograph taken as partof a periodontal assessment alsoreveals a previously undiagnosedand asymptomatic periradicularlesion on the palatal root of toothUL6 (26).

PRACTICE


05p231-238.qxd 12/08/2004 12:17

Pulp testing Pulp testing is often referred to as ‘vitality’ test-ing. In fact, a moribund pulp may still give apositive reaction to one of the following testsas the nervous tissue may still function inextreme states of disease. It is also, of course,possible in a multirooted tooth for one rootcanal to be diseased, but another still capableof giving a vital response. Pulp testers shouldonly be used to assess vital or non-vital pulps;they do not quantify disease, nor do they meas-ure health and should not be used to judge thedegree of pulpal disease. Pulp testing gives noindication of the state of the vascular supplywhich would more accurately indicate thedegree of pulp vitality. The only way pulpalblood-flow may be measured is by using aLaser-Doppler Flow Meter, not usually avail-able in general practice!

Doubt has been cast on the efficacy of pulptesting the corresponding tooth on the other sideof the mid-line for comparison, and it is sug-gested that only the suspect teeth are tested.

Electronic The electric pulp tester is an instrument whichuses gradations of electric current to excite aresponse from the nervous tissue within the pulp.Both alternating and direct current pulp testersare available, although there is little difference

between them. Most pulp testers manufacturedtoday are monopolar (Fig. 6).

As well as the concerns expressed earlierabout pulp testing, electric pulp testers may givea false-positive reading due to stimulation ofnerve fibres in the periodontium. Again, posteri-or teeth may give misleading readings since acombination of vital and non-vital root canalpulps may be present. The use of gloves in thetreatment of all dental patients has producedproblems with electric pulp testing. A lip elec-trode attachment is available which may beused, but a far simpler method is to ask thepatient to hold on to the metal handle of the pulptester. The patient is asked to let go of the handleif they feel a sensation in the tooth being tested.

The teeth to be tested are dried and isolatedwith cotton wool rolls. A conducting mediumshould be used; the one most readily available istoothpaste. Pulp testers should not be used onpatients with pacemakers because of the possi-bility of electrical interference.

Teeth with full crowns present problems withpulp testing. A pulp tester is available with aspecial point fitting which may be placedbetween the crown and the gingival margin.There is little to commend the technique of cut-ting a window in the crown in order to pulp test.

Thermal pulp testingThis involves applying either heat or cold to atooth, but neither test is particularly reliable andmay produce either false-positive or false-negative results.

HeatThere are several different methods of applyingheat to a tooth. The tip of a gutta-percha stickmay be heated in a flame and applied to a tooth.Take great note that hot gutta-percha may stickfast to enamel, and it is essential to coat thetooth with vaseline to prevent the gutta-perchasticking and causing unnecessary pain to thepatient. Another method is to ask the patient tohold warm water in the mouth, which will act onall the teeth in the arch, or to isolate individualteeth with rubber dam and apply warm waterdirectly to the suspected tooth. This is exploredfurther under local anaesthesia.

ColdThree different methods may be used to apply acold stimulus to a tooth. The most effective is theuse of a –50°C spray, which may be applied usinga cotton pledget (Fig. 7). Alternatively, thoughless effectively, an ethyl chloride spray may beused. Finally, ice sticks may be made by fillingthe plastic covers from a hypodermic needle withwater and placing in the freezing compartmentof a refrigerator. When required for use one coveris warmed and removed to provide the ice stick.However, false readings may be obtained if theice melts and flows onto the adjacent tissues.

Local anaestheticIn cases where the patient cannot locate the pain

Fig. 5 A gutta-percha point has beenthreaded into a sinus tract adjacent toa recently root-treated canine (a). Theradiograph (b) reveals the source of theinfection to be the first premolar.

a

b

Fig. 6 A modern electric pulp testercombined with an endodontic apexlocator.


PRACTICE

05p231-238.qxd 12/08/2004 11:57 Page 234

and routine thermal tests have been negative, areaction may be obtained by asking the patient tosip hot water from a cup. The patient is instructedto hold the water first against the mandibularteeth on one side and then by tilting the head, toinclude the maxillary teeth. If a reaction occurs,an intraligamental injection may be given toanaesthetise the suspect tooth and hot water isthen again applied to the area; if there is no reac-tion, the pulpitic tooth has been identified. Itshould be borne in mind that a better term forintraligamental is intra-osseous, as the localanaesthetic will pass into the medullary spacesround the tooth and may possibly also affect theproximal teeth.

Wooden stickIf a patient complains of pain on chewing andthere is no evidence of periapical inflammation,an incomplete fracture of the tooth may be sus-pected. Biting on a wood stick in these cases canelicit pain, usually on release of biting pressure.

Fibre-optic lightA powerful light can be used for transilluminat-ing teeth to show interproximal caries, fracture,opacity or discoloration. To carry out the test,the dental light should be turned off and thefibre-optic light placed against the tooth at thegingival margin with the beam directed throughthe tooth. If the crown of the tooth is fractured,the light will pass through the tooth until itstrikes the stain lying in the fracture line; thetooth beyond the fracture will appear darker.

Cutting a test cavityWhen other tests have given an indeterminateresult, a test cavity may be cut in a tooth whichis believed to be pulpless. In the author’s opin-ion, this test can be unreliable as the patient maygive a positive response although the pulp isnecrotic. This is because nerve tissues can con-tinue to conduct impulses for some time in theabsence of a blood supply.

TREATMENT PLANNINGHaving taken the case history and carried out therelevant diagnostic tests, the patient’s treatment isthen planned. The type of endodontic treatmentchosen must take into account the patient’s med-ical condition and general dental state. The indi-cations and contra-indications for root canaltreatment are given below and the problems of re-root treatment discussed. The treatment of frac-tured instruments, perforations and perio-endolesions are discussed in subsequent chapters.

It should be emphasised here that there is aconsiderable difference between a treatmentplan and planning treatment. Figure 8 shows aradiograph of a patient with a severe endodonticproblem. A diagnosis of failed root canal treat-ments, periapical periodontitis (both apicallyand also associated with a perforation of oneroot), and failed post crowns could be made. Atreatment plan for this patient may beorthograde re-root canal treatment, with repair

of the perforation, followed by the provision ofnew posts and cores, and crowns.

However, success in this case may dependupon the correct planning of treatment. Forexample, what provisional restorations will beused during the root canal treatment, and duringthe following re-evaluation period. Temporarypost-crowns have been shown to be very poor atresisting microleakage.4 The provision of a tem-porary over denture, enabling the total sealingof the access cavities, would seem an appropri-ate alternative, but if this has not been properlyplanned for, problems may arise and successfultreatment may be compromised.

INDICATIONS FOR ROOT CANAL TREATMENTAll teeth with pulpal or periapical pathology arecandidates for root canal treatment. There are alsosituations where elective root canal treatment isthe treatment of choice.

Post spaceA vital tooth may have insufficient tooth sub-stance to retain a jacket crown so the tooth mayhave to be root-treated and restored with a post-retained crown (Fig. 9).

OverdentureDecoronated teeth retained in the arch to pre-serve alveolar bone and provide support orremovable prostheses must be root-treated.

Teeth with doubtful pulpsRoot treatment should be considered for anytooth with doubtful vitality if it requires an exten-sive restoration, particularly if it is to be a bridgeabutment. Such elective root canal treatment hasa good prognosis as the root canals are easy toaccess and are not infected. If the indications are

Fig. 7 A more effective source ofcold stimulus for sensibility testing.

Fig. 8 This complicated case exhibits a number ofdifferent endodontic problems, and requires carefultreatment planning if success is to be achieved.


PRACTICE

05p231-238.qxd 12/08/2004 11:58 Page 235

ignored and the treatment deferred until the pulpbecomes painful or even necrotic, access throughthe crown or bridge will be more restricted, andtreatment will be significantly more difficult, witha lower prognosis.5

Risk of exposurePreparing teeth for crowning in order to alignthem in the dental arch can risk traumatic expo-

sure. In some cases these teeth should be elec-tively root-treated.

Periodontal diseaseIn multirooted teeth there may be deep pocket-ing associated with one root or the furcation.The possibility of elective devitalisation follow-ing the resection of a root should be considered(see Part 9).

Pulpal sclerosis following traumaReview periapical radiographs should be takenof teeth which have been subject to trauma. If progressive narrowing of the pulp space isseen due to secondary dentine, elective rootcanal treatment may be considered while thecoronal portion of the root canal is still patent.This may occasionally apply after a pulpotomyhas been carried out. However, Andreasen6

refers to a range of studies that show a maxi-mum of 16% of sclerosed teeth subsequentlycause problems, and the decision over rootcanal treatment must be arrived at after fullconsultation with the patient. If the sclerosingtooth is showing the classic associated discol-oration the patient may elect for treatment, butotherwise the tooth may better be left alone(Fig. 10).

CONTRA-INDICATIONS TO ROOT CANALTREATMENTThe medical conditions which require specialprecautions prior to root canal treatment havealready been listed. There are, however, otherconditions both general and local, which maycontra-indicate root canal treatment.

GeneralInadequate accessA patient with restricted opening or a smallmouth may not allow sufficient access for rootcanal treatment. A rough guide is that it mustbe possible to place two fingers between themandibular and maxillary incisor teeth so thatthere is good visual access to the areas to betreated. An assessment for posterior endodon-tic surgery may be made by retracting thecheek with a finger. If the operation site can be seen directly with ease, then the access issufficient.

Poor oral hygieneAs a general rule root canal treatment shouldnot be carried out unless the patient is able tomaintain his/her mouth in a healthy state, orcan be taught and motivated to do so. Excep-tions may be patients who are medically orphysically compromised, but any treatmentafforded should always be in the best long-terminterests of the patient.

Patient�s general medical conditionThe patient’s physical or mental condition due to,for example, a chronic debilitating disease or oldage, may preclude endodontic treatment. Similar-ly, the patient at high risk to infective endocardi-

Fig. 10 A 23-year-old female patientsuffered trauma to tooth UL1 (21) whenaged 16, and is complaining about theyellow discoloration of the tooth (a). Aradiograph (b) reveals that the pulpspace has sclerosed.

a

b

Fig. 9 Tooth UL1 (21) requires acrown, but there is insufficientcoronal tissue remaining. Onepossible treatment plan would beelective endodontic treatmentfollowed by the provision of a post-retained core build-up and crown.


PRACTICE

05p231-238.qxd 12/08/2004 11:59 Page 236

tis, for example one who has had a previousattack, may not be considered suitable for com-plex endodontic therapy.

Patient�s attitudeUnless the patient is sufficiently well motivated,a simpler form of treatment is advised.

LocalTooth not restorableIt must be possible, following root canal treat-ment, to restore the tooth to health and function(Fig. 11). The finishing line of the restoration mustbe supracrestal and preferably supragingival.

An assessment of possible restorative problemsshould always be made before root canal treat-ment is prescribed.

Insufficient periodontal supportProvided the tooth is functional and theattachment apparatus healthy, or can be madeso, root canal treatment may be carried out.

Non-strategic tooth Extraction should be considered rather thanroot canal treatment for unopposed and non-functional teeth.

Root fractures Incomplete fractures of the root have a poor prog-nosis if the fracture line communicates with theoral cavity as it becomes infected. For this reason,vertical fractures will often require extraction ofthe tooth while horizontal root fractures have amore favourable prognosis (Fig. 12).

Internal or external resorption Both types of resorption may eventually lead to

pathological fracture of the tooth. Internal resorp-tion ceases immediately the pulp is removed and,provided the tooth is sufficiently strong, it may beretained. Most forms of external resorption willcontinue (see Part 9) unless the defect can berepaired and made supragingival, or arrested withcalcium hydroxide therapy.

Bizarre anatomy Exceptionally curved roots (Fig. 13), dilacer-ated teeth, and congenital palatal groovesmay all present considerable difficulties ifroot canal treatment is attempted. In addition,any unusual anatomical features related to theroots of the teeth should be noted as thesemay affect prognosis.

Re-root treatmentOne problem which confronts the generaldental practitioner is to decide whether aninadequate root treatment requires replace-ment (Fig. 14). The questions the operatorshould consider are given below.

Fig. 11 Tooth UL1 (21) was so extensively decayedsubgingivally that restoration would have provedimpossible even if endodontic treatment had been carriedout.

Fig. 12 The vertical root fracture can be clearly seen inthis extracted tooth which had been fitted with a postcrown.

Fig. 13 The tooth UR4 (14) has such abizarre root canal anatomy thatendodontic treatment would probablybe impossible.


PRACTICE

05p231-238.qxd 12/08/2004 12:00 Page 237

1 Is there any evidence that the old root fillinghas failed?• Symptoms from the tooth.• Radiolucent area is still present or has

increased in size.• Presence of sinus tract.

2 Does the crown of the tooth need restoring?3 Is there any obvious fault with the present

root filling which could lead to failure?

Practitioners should be particularly awareof the prognosis of root canal re-treatments.As a rule of thumb, taking the average of thesurveys reported in the endodontic literature(see Part 12) suggests a prognosis of 90–95%for an initial root canal treatment of a toothwith no radiographic evidence of a periradicu-lar lesion. When such a lesion is present prog-nosis will fall to around 80–85%, and thelonger the lesion has been present the moreestablished will be the infection, treatment (ieremoval of that infection from the entire rootcanal system) will be more difficult and theprognosis significantly lower. The averagereported prognosis for re-treatment of a failed

root canal filling of a tooth with a periradicu-lar lesion falls to about 65%.

The final decision by the operator on the treat-ment plan for a patient should be governed by thelevel of his/her own skill and knowledge. Generaldental practitioners cannot become experts in allfields of dentistry and should learn to be aware oftheir own limitations. The treatment plan pro-posed should be one which the operator is confi-dent he/she can carry out to a high standard.

1. Dental Practitioners’ Formulary 2000/2002. BritishDental Association. BMA Books, London

2. Scully C, Cawson R A. Medical problems in dentistry. Oxford: Butterworth-Heinemann, p74, 1998.

3. National Radiographic Protection Board. GuidanceNotes for Dental Practitioners on the safe use of x-ray equipment. 2001. Department of Health,London, UK.

4. Fox K, Gutteridge D L. An in vitro study of coronalmicroleakage in root-canal-treated teeth restored bythe post and core technique. Int Endod J 1997; 30:361–368.

5. Ørstavik D. Time-course and risk analysis of thedevelopment and healing of chronic apicalperiodontitis in man. Int Endod J 1996; 29: 150–155.

6. Andreasen J O, Andreasen F M. Chapter 9 in Textbookand colour atlas of traumatic injuries to the teeth. 3rdEd, Denmark, Munksgard 1994.

Fig. 14 Tooth UL4 (24) has previouslybeen root treated (and obturated withsilver points) but is symptomless.However, the tooth now requires a fullcrown restoration. A decision must bemade as to whether the tooth shouldbe re-treated before fitting theadvanced restoration.


PRACTICE

British Dental Journal, January 1954

SSuubbssccrriippttiioonnss 11995544

Members are reminded that the Annual Subscription for the Association was due on January 1,1954. If not already paid this should be sent at the earliest possible moment. The rates of subscrip-tion for 1954 are as follows:

£ s. d.Ordinary members 6 6 0Service members 4 14 6Retired members 2 12 6Overseas members 3 13 6Members within three years from qualifying 3 13 6Affiliated members 2 12 6

Fifty years ago today

05p231-238.qxd 12/08/2004 12:01 Page 238

shilpa

Rectangle


PRACTICE

Endodontics: Part 3Treatment of endodontic emergenciesP. Carrotte1

The swift and correct diagnosis of emergency problems is essential when providing treatment, especially in a busy dentalpractice. A diagnosis must be made and appropriate treatment provided in usually just a few minutes. The sequence consideredhere encompasses problems presenting before, during and after dental treatment. Various diagnostic aids are considered, andsome unusual presenting conditions discussed.

● Before any dental treatment is provided it is essential that the patient�s symptoms have beencorrectly diagnosed.

● Conditions causing dental pain on first presentation may include pulpitis (reversible orirreversible), periapical periodontitis, dental abscess, as well as cracked tooth syndrome andother oro-facial pain disorders.

● Conditions arising during treatment may include high restorations, (probably the mostcommon), root or crown fractures, problems with root canal instrumentation and infection.

● Following treatment pain may be due to any of the above, or failure of the root canal treatment.However, patients should always be cautioned to expect a certain amount of post-treatmentdiscomfort.

I N B R I E F

The aim of emergency endodontic treatment isto relieve pain and control any inflammation orinfection that may be present. Although insuffi-cient time may prevent ideal treatment frombeing carried out, the procedures followedshould not prejudice any final treatment plan. Ithas been reported that nearly 90% of patientsseeking emergency dental treatment have symp-toms of pulpal or periapical disease.1,2

Patients who present as endodontic emergen-cies can be divided into three main groups.

Before treatment:1. Pulpal pain

a) Reversible pulpitisb) Irreversible pulpitis

2. Acute periapical abscess3. Cracked tooth syndrome

Patients under treatment:1. Recent restorative treatment2. Periodontal treatment3. Exposure of the pulp4. Fracture of the root or crown5. Pain as a result of instrumentation

a) acute apical periodontitis b) Phoenix abscess

Post-endodontic treatment:1. High restoration2. Overfilling3. Root filling4. Root fracture

BEFORE TREATMENTDetails of the patient�s complaint should be

considered together with the medical history.The following points are particularly relevantand are covered more fully in Part 2.1. Where is the pain?2. When was the pain first noticed?3. Description of the pain.4. Under what circumstances does the pain

occur?5. Does anything relieve it?6. Any associated tenderness or swelling.7. Previous dental history:

a) recent treatment; b) periodontal treatment; c) any history of trauma to the teeth.

Particular note should be made of any disor-ders which may affect the differential diagnosisof dental pain, such as myofascial pain dysfunc-tion syndrome (MPD), neurological disorderssuch as trigeminal neuralgia, vascular pain syndromes and maxillary sinus disorders.

Diagnostic aids� Periapical radiographs taken with a parallel-

ing technique.� Electric pulp tester for testing pulpal

responses.� Ice sticks, hot gutta-percha, cold spray and

hot water for testing thermal responses.3

� Periodontal probe.

Pulpal painThe histological state of the pulp cannot beassessed clinically.4,5 Nevertheless, the signs andsymptoms associated with progressive pulpal

3

















06p299-305.qxd 24/08/2004 11:24 Page 299

norms

Text Box


PRACTICE


and periapical disease can give a reasonableindication of the likely state of an inflamed pulp,that is whether it is reversibly or irreversiblydamaged.6

Irritation of the pulp causes inflammation,and the level of response will depend on theseverity of the irritant. If it is mild, the inflam-matory process may resolve in a similar fashionto that of other connective tissues; a layer ofreparative dentine may be formed as protectionfrom further injury. However, if the irritation ismore severe, with extensive cellular destruction,further inflammatory changes involving the restof the pulp will take place, which could eventu-ally lead to total pulp necrosis.

There are features of pulpitis which can makethe borderline between reversible and irreversiblepulpitis difficult to determine clinically. In gener-al, if the responses to several tests are exaggerat-ed, then an irreversible state is possible.

The essential feature of a reversible pulpitis isthat pain ceases as soon as the stimulus isremoved, whether it is caused by hot or cold flu-ids, or sweet food. The teeth are not tender topercussion, except when occlusal trauma is afactor. Initially, one of the following treatmentmay be all that is necessary:� Check the occlusion and remove non-

working facets.� Place a sedative dressing in a cavity after

removal of deep caries.� Apply a fluoride varnish or a dentine bond-

ing resin to sensitive dentine and prescribe adesensitizing toothpaste.

Should the symptoms persist and the level ofpain increase in duration and intensity, then thepulpitis is likely to be irreversible. The patientmay be unable to decide which tooth is causingthe problem, since the pain is often referred toteeth in both the upper and lower jaw on thesame side. In the early stages, the tooth mayexhibit a prolonged reaction to both hot andcold fluids, but is not necessarily tender to per-cussion. When testing for sensitivity to percus-sion it is not necessary to tap the tooth with thehandle of dental instrument. Gentle fingerpressure will be more than sufficient to elicit aresponse, and much kinder to your patient.

Only when the inflammation has spreadthroughout the pulp and has involved the peri-odontal ligament, will the tooth become tenderto bite on. In these circumstances, the applica-tion of heat will cause prolonged pain whichmay be relieved by cold. Both hot and cold canprecipitate a severe bout of pain, but as a ruleheat tends to be more significant.

Pain from an irreversibly damaged pulp canbe spontaneous and may last from a few secondsto several hours. A characteristic feature of anirreversible pulpitis is when a patient is woken atnight by toothache. Even so, if untreated asymptomatic pulpitis may become symptomlessand pulp tests may give equivocal results. Intime, total pulp necrosis may ensue, without thedevelopment of further symptoms and the firstindication of an irreversibly damaged pulp maybe seen as a periapical rarefaction on a radi-ograph, or the patient may present with an acuteperiapical abscess.

To summarize, therefore, in reversible pulpitis:� The pain is of very short duration and does

not linger after the stimulus has beenremoved.

� The tooth is not tender to percussion.� The pain may be difficult to localize.� The tooth may give an exaggerated response

to vitality tests.� The radiographs present with a normal

appearance, and there is no apparentwidening of the periodontal ligaments.

In irreversible pulpitis:� There is often a history of spontaneous bouts

of pain which may last from a few secondsup to several hours.

� When hot or cold fluids are applied, the painelicited will be prolonged. In the later stages,heat will be more significant; cold mayrelieve the pain.

� Pain may radiate initially, but once the peri-odontal ligament has become involved, thepatient will be able to locate the tooth.

� The tooth becomes tender to percussion onceinflammation has spread to the periodontalligament.

� A widened periodontal ligament may beseen on the radiographs in the later stages.

Careful evaluation of a patient�s dental historyand of each test is important. Any one test on itsown is an insufficient basis on which to make adiagnosis. Records and radiographs should firstbe checked for any relevant information such asdeep caries, pinned restorations, and the appear-ance of the periodontal ligament space (Fig. 1).Vitality tests can be misleading, as various fac-tors have to be taken into account. For example,the response in an older person may differ fromthat in someone younger due to secondary den-tine deposition and other atrophic changes inthe pulp tissue. Electric pulp testing is simply anindication of the presence of vital nerve tissue inthe root canal system only and not an indicationof the state of health of the pulp tissue.

Fig. 1 Initialradiographicassessment.Radiographs should bechecked for anyrelevant informationsuch as deep caries,pinned restorations,and the appearance ofthe periodontalligament space.

06p299-305.qxd 24/08/2004 11:25 Page 300

PRACTICE


Once pulpal inflammation has spread to theperiodontal ligament, the resulting inflammato-ry exudate may cause extrusion of the tooth,making it tender to bite on. This particularsymptom, acute apical periodontitis, may be aconsequence of occlusal trauma; the occlusionmust therefore always be checked.

Ideally, the treatment for irreversible pulpitisis pulp extirpation followed by cleaning andpreparation of the root canal system. If time doesnot permit this, then removal of pulp tissue fromthe pulp chamber and from the coronal part ofthe root canal is often effective. Irrigation of thepulp chamber using a solution of sodiumhypochlorite before carrying out any instrumen-tation is important. (Sodium hypochlorite is usu-ally sold as a 5% solution. This may be dilutedwith purified water BP to the operator�s prefer-ence.) Sodium hypochlorite solution has provedto be one of the most effective disinfectingagents used in root canal treatment,7,8 with dif-ferent authors recommending strengths between0.5 and 5.0%. The pulp chamber and root canalsare dried, and a dry sterile cotton wool pledgetplaced in the pulp chamber with a temporaryfilling to seal the access cavity. Antiseptic solutions such as phenolic solutions or corticos-teroid/ antibiotic preparations on cotton woolpledgets have been advocated, but their effec-tiveness is of doubtful value. Corticosteroiddressings should be used sparingly as there isevidence that suppression of an inflammatoryresponse by steroids allows bacteria to enter thebloodstream with ease.9 This is a particularlyundesirable effect in patients who, for example,have a history of rheumatic fever. Studies haveshown that provided the pulp chamber and theroot canals have been cleansed and dried, med-ication of the pulp chamber and root canals is oflittle practical benefit. Paper points are used todry the canals and under no circumstancesshould they be left in the canal, otherwise anyfluid that enters the canal system will beabsorbed and so provide an effective culturemedium for any residual bacteria.

Difficulty with local analgesia is a commonproblem with an acutely inflamed pulp. In

addition to standard techniques, supplemen-tary analgesia can be obtained with the fol-lowing:1 Additional infiltration anaesthesia, such as

long-buccal, lingual and palatal.2 Intraligamental (intra-osseous) injection.3 True intra-osseous injection.4 Intrapulpal analgesia.5 Inhalational sedation with local analgesia.

Should these techniques give only moderatesuccess, it is advisable to dress the pulp to allowthe inflammation to subside and to postponepulp extirpation. A corticosteroid/antibioticpreparation with a zinc oxide/eugenol tempo-rary restoration will provide an effective, short-term dressing.

Continuation of pain following pulp extirpa-tion may be due to one of the following causes.1 The temporary filling is high.2 Infected pulp tissue is present in the canal.3 Some of the canal contents have been

extruded through the apex.4 Overinstrumentation of the apex or perfora-

tion of the canal wall.5 An extra canal may be present which has not

been cleaned.

If the problem is not found to be occlusal,whatever the cause the remedy is to irrigate thepulp chamber and root canal system again withsodium hypochlorite solution and perhaps gen-tly instrument, then dry and redress the tooth asbefore.

Acute periapical abscessThis condition develops from an acute periapi-cal periodontitis. In the early stages, the differ-ence between the two is not always clear. Radi-ographic changes range from a widening of theperiodontal ligament space (Fig. 2), to a well-defined area (Fig. 3). The typical symptoms ofan acute periapical abscess are a pronounced

Fig. 2 Radiographic changes range from a widening of the periodontalligament space (note that this upper first premolar has two separate buccalroots)�

Fig. 3 � to a large,well-defined areaof radiolucency.

06p299-305.qxd 24/08/2004 11:26 Page 301

PRACTICE


soft-tissue swelling (Fig. 4) and an exquisitelytender tooth. Extrusion from the socket willoften cause the tooth to be mobile. Differentialdiagnosis of a suspected periapical swelling isimportant in case the cause is a lateral peri-odontal abscess. The diagnosis can be made bytesting the vitality of the tooth. If it is vital, thenthe cause may well be periodontal in origin.

The immediate task is to relieve pressure byestablishing drainage, and in the majority ofcases this can be achieved by first opening upthe pulp chamber, as seen in Figure 5. Initially,gaining access can be difficult because thetooth is often extremely tender. Gently grip thetooth and use a small, round, diamond bur in aturbine to reduce the trauma of the operation.Regional analgesia may be necessary, andinhalation sedation can prove invaluable. Ifdrainage is not immediate it is permissible toexplore the apical foramen with a very fine(size 08 or 10) file. The foramen should not beinstrumented or enlarged, and if drainage doesnot result the procedure should not be perse-vered. As discussed in Part 7, the use of ultra-sonically activated endodontic files may beparticularly helpful in this situation for effec-tively flushing infected debris from the rootcanal system.

If a soft-tissue swelling is present and point-ing intra-orally, then it may be incised to estab-lish drainage as well. The presence of a cellulitismay result in little or no drainage. If a cellulitis ispresent, medical advice should be sought beforeany treatment is carried out (Fig. 6).

Incision to establish drainageIncision to establish drainage is the only surgi-cal endodontic procedure which may be under-taken when acute inflammation is present. Theprincipal indication is the presence of a collec-tion of pus which points from a fluctuantabscess in the soft tissues. Establishing drainageto help bring the infection under control isessential, and should always be obtainedthrough the root canal and soft tissues in prefer-ence to administering antibiotics alone. The

soft-tissue swelling should be examined to seeif it is fluctuant. Where the swelling is pointingintra-orally, copious amounts of surface anal-gesia should be applied, for example ethyl chlo-ride or topical lignocaine ointment. Regionalanaesthesia may not be effective due to thepresence of pus, and the administration of alocal analgesic solution may spread the infec-tion further into the tissues.

Incise the swelling with a Bard�Parker No. 11or 15 scalpel blade, or aspirate, using a wide-bore needle and disposable syringe. It may bepossible to aspirate the abscess via the root canalas well. The advantage of this technique is thatthe sample can be sent for bacteriological exam-ination if required. It is not usually necessary toinsert a drain, but if it is thought necessary thena piece of quarter-inch or half-inch selvedgegauze may be used. The same criteria applywhen extra-oral drainage is indicated, and itmay be possible to use the same technique ofaspiration with a wide-bore needle and dispos-able syringe. However, if an extra-oral incisionis considered necessary, as in Figure 7, it is wiseto refer the patient to an oral surgeon for thisparticular procedure.

Root canal treatmentOnce access and initial drainage have beenachieved, a rubber dam should be applied to thetooth to complete the operation. Before any fur-ther instrumentation is carried out, the pulpchamber should be thoroughly irrigated with asolution of sodium hypochlorite to remove asmuch superficial organic and inorganic debrisas possible. This in itself may bring considerablepain relief and will make subsequent instru-mentation easier. Having debrided the canals tothe best possible extent with frequent changesof irrigant, the canals should be dried withpaper points and a dry sterile cotton wool pled-get placed in the pulp chamber to preventingress of the temporary dressing. The accesscavity is then sealed to prevent re-infection ofthe canals from the oral cavity. If completedebridement was not possible the patient must

Fig. 5 Immediate relief is obtained as pus drains feely from an access cavity.

Fig. 4 A pronouncedswelling may bepresent adjacent to theabscessed tooth.

06p299-305.qxd 24/08/2004 11:26 Page 302

PRACTICE


be recalled within 48 hours. At this time it willusually be possible to complete instrumentationand place a calcium hydroxide dressing in thecanals.

The temptation to leave the tooth open todrain must be resisted at all costs.10 The micro-bial flora of the canal will be changed, makingtreatment more difficult and lowering the long-term prognosis. Furthermore, this treatmentcontravenes the prime objective of treatment: todisinfect the root canal. If the clinician does nothave sufficient time to carry out adequate treat-ment when opening the tooth, good clinicalpractice would suggest re-appointing the patientto the end of the treatment session when time isavailable.

Antibiotics are only required when there issystemic spread of the infection, the patient isunwell and has a raised temperature. Antibi-otics are not an alternative to appropriatecleaning and disinfection of the root canal.11

There is a serious tendency to over prescriptionof antibiotics in situations where they are notindicated. If, however, there is a clinical reasonfor their use, amoxycillin is usually the agent ofchoice, prescribing 250 mg three times a dayuntil the infection is under control and rootcanal therapy initiated. Metronidazole is a use-ful alternative where the penicillins are contra-indicated.

CRACKED TOOTH SYNDROME (POSTERIOR TEETH)Crazing of the enamel surface is a common find-ing on teeth as a consequence of function, buton occasion it may indicate a cracked tooth. Ifthe crack runs deep into dentine and is thereforea fracture, chewing may be painful. Initially, thismay not be of sufficient intensity for the patientto seek treatment. However, once the fractureline communicates with the pulp, pulpitis willensue. A quiescent period of several months may

follow before any further symptoms develop.The patient may present with a whole range ofbizarre symptoms, many of which are similar tothose of irreversible pulpitis:� Pain on chewing.� Sensitivity to hot and cold fluids.� Pain which is difficult to localize.� Pain referred along to the areas served by the

fifth cranial nerve.� Acute pulpal pain.� Alveolar abscess.

Diagnosis can be difficult and much dependson the plane of the fracture line and its site onthe tooth. Radiographs are unlikely to reveal afracture unless it runs in a buccolingual plane.A fibre-optic light is a useful aid as it will oftenreveal the position of the fracture. One diag-nostic test is to ask the patient to bite on a pieceof folded rubber dam. Care must be exercised asthis test may extend the fracture line. Theextent of the fracture line and its site willdecide whether the tooth can be saved or not. Ifit is a vertical fracture, involves the root canalsystem and extends below the level of the alve-olar crest, then the prognosis is poor andextraction is indicated (Fig. 8). However, if thefracture line is horizontal or diagonal andsuperficial to the alveolar crest, then the prog-nosis may be better.

Fig. 6 A teenage patient who had a large periapicallesion of a lower incisor is developing a cellulitis.

Fig. 7 External incisionmay be required, andthe patient shouldpreferably be referredto a general surgeon.

Fig 8 A patient whocomplained of classic�cracked-cusp� painwas found to have sucha deep subgingival cuspfracture that the toothwas extracted.

06p299-305.qxd 24/08/2004 11:28 Page 303

PRACTICE


PATIENTS UNDER TREATMENTFollowing endodontic procedures, patients maysometimes experience pain no matter how care-fully the treatment has been given. It would beprudent to warn every patient to expect a certainamount of discomfort following endodontictreatment, advising them that this is caused byan inflammatory response at the tooth apex.They should be advised to take over-the-counteranalgesics, preferably NSAIDs. However, if thepain persists for more than two or three days,further treatment is probably required for one ofthe following reasons.

Recent restorationsPain may be a result of:� High filling� Microleakage� Micro-exposure of the pulp� Thermal or mechanical injury during cavity

preparation or an inadequate lining undermetallic restorations

� Chemical irritation from lining or fillingmaterials

� Electrical effect of dissimilar metals.

It is not always possible to know beforehandwhether there is a pre-existing pulpal conditionwhen operative procedures are undertaken. Con-sequently, a chronic pulpitis may be convertedinto an acute pulpitis.

Periodontal treatmentThere is always a chance that some of thenumerous lateral canals that communicate withthe periodontal ligament are exposed when peri-odontal treatment is carried out. This aspect isconsidered in the section in Part 9 on �perio-endo lesions�.

Exposure of the pulpIf a carious exposure is suspected, then removalof deep caries should be carried out under rubberdam. The decision to extirpate the pulp or carryout either a pulp capping or partial pulpotomyprocedure depends on whether the pulp has beenirreversibly damaged or not (see Part 9 � calci-um hydroxide). If there is insufficient time, orany difficulty is experienced with analgesia,temporary treatment, as recommended for irre-versible pulpitis, may be carried out.

Root or crown fracturesMost root or crown fractures can be avoided byadequately protecting the tooth during a courseof root canal treatment. If the structure of thetooth is damaged between appointments, pain islikely to occur as a result of salivary and bacteri-al contamination of the root canal. If the toothhappens to fracture in a vertical plane, the prog-nosis is poor and the tooth may have to beextracted (Fig. 9). In the case of multirootedteeth, it may be possible to section the tooth andremove one of the roots.

Pain as a result of instrumentationThe two conditions that may require emergencytreatment during a course of root canal treat-ment are:� acute apical periodontitis;� Phoenix abscess.

Acute apical periodontitis may arise as a resultof over instrumentation, extrusion of the canalcontents through the apex, leaving the tooth intraumatic occlusion, or placing too muchmedicament in the pulp chamber as an inter-appointment dressing.

Irrigation of the canal with sodium hypochloriteand careful drying with paper points is usuallysufficient to alleviate the symptoms. The occlusionmust be checked, as there is likely to be a certainamount of extrusion of the tooth from its socket.

The term �Phoenix abscess� relates to the sud-den exacerbation of a previously symptomlessperiradicular lesion. It can be one of the mosttroublesome conditions to deal with and occursafter initial instrumentation of a tooth with apre-existing chronic periapical lesion (Fig. 10).The reasons for this phenomenon are not fullyunderstood, but it is thought to be due to analteration of the internal environment of the rootcanal space during instrumentation which acti-vates the bacterial flora. Research has shown thatthe bacteriology of necrotic root canals is morecomplex than was previously thought, in partic-ular the role played by anaerobic organisms.

Treatment consists of irrigation, debridementof the root canal and establishing drainage. In

Fig. 9 Root orcrown fractures canoften be avoided byprotecting thetooth duringendodontictreatment, andproviding cuspalcoverage followingtreatment. If thetooth fractures inthe vertical planethe prognosis ispoor.

Fig. 10 Phoenix abscess. Endodontic treatment wascommenced on this tooth with a chronic periradicularlesion, which had previously been symptomless. Thepatient returned 2 days later with extreme pain andswelling.

06p299-305.qxd 24/08/2004 11:28 Page 304

PRACTICE


severe cases, it may be necessary to prescribe anantibiotic.

POST-ENDODONTIC TREATMENTThe following factors need to be consideredshould pain occur following sealing of the rootcanal system.� High restoration� Overfilling� Underfilling� Root fracture

Once obturation of the root canal space hasbeen completed, restoration of the rest of thetooth can be carried out. The occlusion must bechecked for interferences, to avoid an apicalperiodontitis, or worse, a fractured tooth.

Root fillings that are apparently overfilled donot as a rule cause more than mild discomfortafter completion. The most likely cause of painfollowing obturation of the root canal space isthe presence of infected material in the periapicalregion. The significance of an underfilled rootcanal is whether the canal has been properlycleaned and prepared in the first instance, andinfected debris is still present in the canal. Post-endodontic pain in these circumstances may wellbe due to inadequate debridement of the canal.

Removal of an overextended root filling israrely completely successful and the options leftare as follows:� Prescription of analgesics and, if the pain is

more severe and infection is present,antibiotics.

� An attempt at removal of the root filling andrepreparation of the root canal.

� Periradicular surgery and apicectomy.

Root fractureThe forces needed to place a satisfactory rootfilling, using the lateral compaction of gutta-percha technique, should not be excessive; toomuch pressure increases the risk of root frac-ture. The most common type of fracture isusually a vertical one and the prognosis is poor.Extraction, or sectioning of the root in the case of a multirooted tooth, is all that can berecommended.

1. Hasler J F, Mitchell D F. Analysis if 1628 cases ofodontalgia: A corroborative study. J IndianapolisDistrict Dent Soc 1963; 17: 23�25.

2. Drinnan D L. Differential diagnosis of orofacial pain.Dent Clin North Am 1987; 31: 627�643.

3. Mosaku A O, Watkins K E E, Grey N J A. The hot watertest: a diagnostic procedure and a case report. CPDDentistry 2000; 1: 101�103.

4. Seltzer S, Bender I B, Zionitz M. The dynamics of pulpinflammation: Correlation between diagnostic dataand histologic findings in the pulp. Oral Surg 1963;16: 846�871, 969�977.

5. Garfunkel A, Sela J, Ulmansky M. Dental pulppathosis; clinico-pathological correlations based on109 cases. Oral Surg 1973; 35: 110�117.

6. Dummer P H, Hicks R, Huws D. Clinical signs andsymptoms in pulp disease. Int Endod J 1980; 13:27�35.

7. Baumgartner J C, Mader C L. A scanning electronmicroscopic evaluation of four root canal irrigationsystems. J Endod 1987; 13: 147�157.

8. Berutti E, Marini R. A scanning electron microscopicevaluation of the debridement capability of sodiumhypochlorite at different temperatures. J Endod 1996;22: 467�470.

9. Watts A, Patterson R C. The response of themechanically exposed pulp to prednisolone andtriamcinolone acetonide. Int Endod J 1988; 21: 9�16.

10. Harrington GW, Natkin E. Midtreatment flare-ups.Dent Clin North Am 1992; 36: 409�423.

11. Longman L P, Preston A J, Martin M V, Wilson N H.Endodontics in the adult patient: the role of antibiotics.J Dent 2000; 28: 539�548.

British Dental Journal, August 1904

EExxcceerrpptt

It seems not improbable that ultimately we may follow the lead of general surgery, anddepend less and less on antiseptics and germicides, which probably destroy the normalbalance of power among the bacteria of the mouth and thus interfere with the naturalstruggle for existence among the different species. Return to natural conditions is thekeynote of preventive medicine of modern times, and that also is the trend of dentalhygiene in so far as the bonds of civilisation permit. At any rate, there is little dispute thatthe thorough cleaning with the brush is of primary importance, and yet it is most ineffi-ciently carried out. In fact, with the carelessness of children and the indifference of manyparents, it is impossible to hope for any dental millenium in regard to hygiene until it isrecognised that instruction in schools is the only way to attain it.

From the Presidential Address delivered by Mr W.H. Williamson at the BDA AnnualGeneral Meeting at Aberdeen, August 1904

Br Dent J 1904


06p299-305.qxd 24/08/2004 11:29 Page 305

kishore

Rectangle

BRITISH DENTAL JOURNAL VOLUME 197 NO. 7 OCTOBER 9 2004 379

PRACTICE

Endodontics: Part 4Morphology of the root canal systemP. Carrotte1

Unless the practitioner is familiar with the morphology of the roots of all teeth, and the associated intricate root canalanatomy, effective debridement and obturation may be impossible. Recent research has improved knowledge andunderstanding of this intricate aspect of dental practice. After studying this part you should know in what percentage of eachtooth type you may expect unusual numbers of root canals and other anatomical variations.

● Practitioners must be aware that the main root canals in a tooth may only provide access tothe complexities of the root canal system, which must be fully cleaned of all microorganisms.

● Research has shown that the dental anatomy learned as a dental student may now be out ofdate.

● Knowledge of canal anatomy is essential in designing and executing access cavities that givestraight line access to the main root canals.

I N B R I E F

This part may seem at first sight the most boringin the book, yet it could be the most important inimproving clinical practice. Both undergraduatestudents and dentists on postgraduate coursesfrequently state that the reason they find rootcanal treatment so difficult, and the reason sur-veys frequently report inadequate treatmentstandards, is because they are working �blind�.Unless a surgical microscope is available it isimpossible to see down the root canal � to visual-ize exactly what the instruments are doing. Anunderstanding of the architecture of the rootcanal system is therefore an essential prerequisitefor successful root canal treatment (see Part 1,Fig. 1). As long ago as 1925, when Hess andZurcher first published their study,1 it becameclear that teeth had complicated root canal sys-tems rather than the simplified canals that hadbeen previously described.

Sadly their work, and many similar publica-tions, have largely been overlooked and den-tists still remain obsessed with the concept of a�root canal�, a hollow tube down a root whichhas to be cleaned and shaped, eventuallyappearing as a nice white line on the post-oper-ative radiograph. Undergraduate students learnthe number of canals in each tooth by rote.However, many teeth have more than onecanal, as described in this part. Where twocanals exist within the same root, for examplethe mesial root of a lower molar, lateral com-munication (anastomosis) in the form of fins oraccessory canals, occurs between them. Evenroots with a single canal will have lateral andaccessory canals leaving the main canal. Unlessthis concept of an entire root canal system isclearly understood, and a method of cleaningand shaping this system employed to addressthese anastomoses as well as the main canals,infection will remain in the root canal system,and the treatment may fail.

ROOT CANAL SYSTEMThe pulp chamber in the coronal part of a toothconsists of a single cavity with projections(pulp horns) into the cusps of the tooth (Fig. 1).With age, there is a reduction in the size of thechamber due to the formation of secondarydentine, which can be either physiological orpathological in origin. Reparative or tertiarydentine may be formed as a response to pulpalirritation and is irregular and less uniform instructure.

The entrances (orifices) to the root canals areto be found on the floor of the pulp chamber,usually below the centre of the cusp tips. Incross-section, the canals are ovoid, having theirgreatest diameter at the orifice or just below it.In longitudinal section, the canals are broaderbucco-lingually than in the mesiodistal plane.The canals taper towards the apex, followingthe external outline of the root. The narrowestpart of the canal is to be found at the �apicalconstriction�, which then opens out as the api-cal foramen and exits to one side between 0.5and 1.0 mm from the anatomical apex. Deposi-tion of secondary cementum may place the api-cal foramen as much as 2.0 mm from theanatomical apex. It must be realized, however,that the concept of a �single� root canal with a�single� apical foramen is mistaken. The rootcanal may end in a delta of small canals, andduring root canal treatment cleaning tech-niques should be employed to address thisclinical situation.

LATERAL AND ACCESSORY CANALSAs previously discussed, lateral canals formchannels of communication between the mainbody of the root canal and the periodontal liga-ment space. They arise anywhere along itslength, at right angles to the main canal. Theterm �accessory� is usually reserved for the small

4
















07p379-383.qxd 07/09/2004 12:31 Page 379

norms

Text Box


PRACTICE

380 BRITISH DENTAL JOURNAL VOLUME 197 NO. 7 OCTOBER 9 2004

canals found in the apical few millimetres andforming the apical delta (Fig. 2). Both lateraland accessory canals develop due to a break in�Hertwig�s epithelial root sheath� or, duringdevelopment, the sheath grows around existingblood vessels. Their significance lies in their rel-atively high prevalence, Kasahara et al.2 finding60% of central incisors with accessory canals,and 45% with apical foramina distant from theactual tooth apex. Kramer found that the diam-eter of some lateral canals was often wider thanthe apical constriction.3 Lateral canals are

impossible to instrument and can only becleaned by effective irrigation with a suitableantimicrobial solution. Consequently, sealingsuch canals is only moderately successful.

The following descriptions of normal canalmorphology and access cavities are illustrated inFigure 3 (maxilliary) and Figure 4 (mandibular).

MAXILLARY CENTRAL INCISORSThese teeth almost always have one canal. Whenviewed on radiographs the canal appears to befairly straight and tapering, but labiopalatallythe canal will tend to curve either towards thelabial or palatal aspect at about the apical thirdlevel. One feature to note is the slight narrowingof the lumen at the cervical level, which immedi-ately opens up into the main body of the canal.The inverted-triangular shaped access cavity iscut with its base at the cingulum to give straightline access.

MAXILLARY LATERAL INCISORSimilar in shape to the central incisors, but frac-tionally shorter, the apical third tends to curvedistally and the canal is often very fine with thinwalls. Labiopalatally, the canal is similar to thecentral incisor, but there is often a narrowing ofthe canal at the apical third level. The root ismore palatally placed, an important point whenany periradicular surgical procedures are carriedout on this tooth. The access cavity is similar tothe central incisor.

MAXILLARY CANINEAs well as being the longest tooth in the mouth,its oval canal often seems very spacious duringinstrumentation. However, there is usually asudden narrowing at the apical 2�3 mm; thisleads to a danger of overinstrumentation if toolarge a file is used at this level. The length of thistooth can be difficult to determine on radi-ographs, as the apex tends to curve labially andthe tooth will appear to be shorter than it actual-ly is. The oval shape of the root canal is reflectedin the shape of the access cavity.

Fig. 3 The basic pulpcanal shape andsuggested access cavityopenings in themaxilliary teeth.

Fig. 4 The basic pulpcanal shape andsuggested accesscavity openings in themandibular teeth.

Fig. 1 The pulpchamber in the coronalpart of the toothconsists of a singlecavity with projections(pulp horns) into thecusps of the tooth.

Fig. 2 The small canals found in the apical few millimetres and forming theapical delta are seen here filled with sealer.

07p379-383.qxd 07/09/2004 12:32 Page 380

PRACTICE


MAXILLARY FIRST PREMOLARTypically, this tooth has two roots with twocanals. In many ways this is the most difficulttooth to treat, as it can have a complex canalsystem. Variations range from one to three roots,(Fig. 5), but there are nearly always at least twocanals present, even if they exit through a com-mon apical foramen. The roots of these teeth arevery delicate and at the apical third they maycurve quite sharply buccally, palatally, mesiallyor distally, so instrumentation needs to be car-ried out with great care (Fig. 6). In a small per-centage of cases the buccal root may subdivideinto two canals in the apical third, as shown inFigure 7. An oval access cavity is cut betweenthe cusp tips, being wider buccopalatally thanmesiodistally.

MAXILLARY SECOND PREMOLARIn 40% of cases, this tooth, which is similar inlength to the first premolar, has one root with asingle canal. Two canals may be found in about58% of cases.4 The configuration of the twocanals may vary with two separate canals andtwo exits, two canals and one common exit, onecanal dividing and having two exits. In onestudy,5 it was found that 59% of maxillary sec-ond premolars had accessory canals. As with thefirst maxillary premolar, the apical third of theroot may curve quite considerably, mainly to thedistal, sometimes buccally. The access cavity issimilar to the first premolar.

MAXILLARY FIRST MOLARThis tooth has three roots. The palatal root isthe longest, with an average length of 22 mm;the mesiobuccal and distobuccal roots areslightly shorter, at 21 mm average length. Thepercentage of mesiobuccal roots having twocanals reported in the literature has increasedsteadily as research techniques have devel-oped. In vitro studies have usually reported ahigher incidence than in vivo studies. Stropko,reporting an extensive in vivo study,6 foundsecond canals in 73% of cases before the useof an operating microscope, but 93% follow-ing its use. The canals of the mesiobuccal rootare often very fine and difficult to negotiate;consequently, more errors in instrumentationoccur in this tooth than in almost any other.Anastomosis between these two canals maytake the form of narrow canals or wide fins,both almost impossible to instrument. Thecurvature of the roots can be difficult to visu-alize from radiographs, and the secondmesiobuccal canal is nearly always superim-posed on the primary mesiobuccal canal. Thepalatal root has a tendency to curve towardsthe buccal and the apparent length on a radi-ograph will be shorter than its actual length.The access cavity represents the shape of thepulp chamber, enlarged slightly, and flared upon to the mesiobuccal aspect of the occlusalsurface to accommodate the angle of instru-ment approach when working at the back ofthe mouth.

MAXILLARY SECOND MOLARThis tooth is similar to the first maxillary molar,but slightly smaller and shorter, with straighterroots and thinner walls. Usually there are onlythree canals and the roots are sometimes fused.The access cavity is the same as for the firstmolar, modified further to accommodate theangle of approach.

MAXILLARY THIRD MOLARThe morphology of this tooth can vary consider-ably, ranging from a copy of the first or secondmaxillary molar to a canal system that is quitecomplex. They are best explored with a wideaccess cavity and direct vision of the individualcanal anatomy.

Fig. 5 Examples of upper premolars with three roots.

Fig. 6 The roots of upper firstpremolars are very delicate and maycurve quite sharply buccally,palatally, mesially or distally, soinstrumentation needs to be carriedout with great care.

Fig. 7 Cross-sectionstaken at differentlevels in a maxillaryfirst premolar showingthe division of thebuccal canal.

07p379-383.qxd 07/09/2004 12:33 Page 381

PRACTICE


MANDIBULAR CENTRAL AND LATERALINCISORSThe morphology of these two teeth is very simi-lar. The central incisor has an average length of20.5 mm and the lateral is a little longer withan average length of 21 mm. Over 40% of theseteeth have two canals, but only just over 1%have two separate foramina. Careful reading ofthe pre-operative radiograph may show achange in the radiodensity of the root canal,indicating division into two separate canals,and a correctly designed access cavity willfacilitate checking for a second canal. This isoval in shape, commencing above the cingu-lum and almost notching the lingual incisaledge.

MANDIBULAR CANINEThis tooth is similar to its opposite number,although not as long. On rare occasions, tworoots may exist and this can cause difficultywith instrumentation (Fig. 8). An oval accesscavity is again indicated.

MANDIBULAR FIRST PREMOLARThe canal configuration of this tooth can bequite complex. Vertucci7 has shown that the sin-gle canal normally found may divide into twocanals and two apical foramina in 25% of cases.It is the way in which the second canal branchesthat can cause difficulty with instrumentation.Occasionally, the canal terminates with anextensive delta, making obturation of the acces-sory canals even more challenging. As in theupper premolars, the access cavity is ovalbetween the cusp tips.

MANDIBULAR SECOND PREMOLARThis tooth is similar to the first premolar, exceptthat the incidence of a second canal is verymuch lower. One study stated this to be 12%.7

Another study revealed that only 2.5% had two

Table 1 Average root canal configurations

Tooth Average Length No. of roots No. of canals

Maxillary anteriors

Central incisor 22.5 mm 1 1

Lateral incisor 22.0 mm 1 1

Canine 26.5 mm 1 1

Maxillary premolar

First premolar 20.6 mm 2-3 1 (6.%)

2 (95%)

3 (1%)

Second premolar 21.5 mm 1-3 1 (75%)

2 (24%)

3 (1%)

Maxillary molars

First molar 20.8 mm 3 4 (93%)

3 (7%)

Second molar 20.0 mm 3 4 (37%)

3 (63%)

Third molar 17.0 mm 1-3

Mandibular anteriors

Central incisor 20.7 mm 1 1 (58%)

2 (42%)

Lateral incisor 20.7 mm 1-2 1 (58%)

2 (42%)

Canine 25.6 mm 1 1 (94%)

2(6%)

Mandibular premolars

First premolar 21.6 mm 1 1 (73%)

2 (27%)

Second premolar 22.3 mm 1 1 (85%)

2 (15%)

Mandibular molars

First molar 21.0 mm 2-3 3 (67%)

4 (33%)

Second molar 19.8 mm 2 2 (13%)

3 (79%)

4 (8%)

Third molar 18.5 mm 1-2

Fig. 8 Lower canines mayoccasionally be found with twoseparate roots.

Fig. 9 A lower secondpremolar with a severedistal curve at theapex.

07p379-383.qxd 07/09/2004 12:34 Page 382

PRACTICE


apical foramina.8 Consequently, it is a much eas-ier tooth to treat compared with the mandibularfirst premolar, unless the radiograph reveals asharp distal curve at the apex as shown in theextracted tooth at Figure 9.

MANDIBULAR FIRST MOLARThis is often the most heavily restored tooth inthe adult dentition and seems to be a frequentcandidate for root canal treatment. Generallythere are two roots and three canals: two canalsin the mesial root and one large oval canal dis-tally. According to Skidmore and Bjorndal,9 onethird of these molars have four canals. Occa-sionally, three roots are to be found: usually twodistal and one mesial (Fig. 10), rarely one distaland two mesial. Anastomoses occur betweenthe canals and accessory communication withthe furcation area is a frequent finding. Themesiobuccal canal tends to exhibit the greatestdegree of curvature. The access cavity onceagain represents the shape of the pulp chamber,enlarged slightly, and flared up on to themesiobuccal aspect of the occlusal surface toaccommodate the angle of instrument approachwhen working at the back of the mouth.

MANDIBULAR SECOND MOLARThis tooth is similar to the mandibular firstmolar, although a little more compact. The mesialcanals tend to lie much closer together, and theincidence of two canals distally is much less. Thistooth seems to be more susceptible to verticalfracture. Occasionally, the root canals may joinin a buccal fin giving a �C-shaped� canal, whichmay lead all the way to the apex.10 The accesscavity is similar to that of the first molar.

MANDIBULAR THIRD MOLARTogether with the maxillary third molar, thistooth displays some of the most irregularcanal configurations to be found in the adultdentition, as seen in Figure 11. However, themesial inclination of the tooth generallymakes access easier. The canal orifices are nottoo difficult to locate, but the degree of curva-ture of the apical half of the root canal systemis often pronounced. Added to this, the apex isfrequently poorly developed and lies close tothe inferior alveolar canal. A large access cav-ity allowing direct visualization of the floor ofthe pulp chamber enables the canal orifices tobe identified.

It should always be remembered that whilstthe above descriptions are the norm, occasional-ly other teeth may be encountered with unusualor even bizarre anatomy. This may only be dis-covered after the treatment has failed and thetooth has been extracted. Clues may sometimesbe found by careful examination of the radi-ographs, especially with the use of magnifica-tion, as described in Part 5.

1. Hess W, Zurcher E. The anatomy of the root canals ofthe teeth of the permanent dentition and the anatomyof the root canals of the deciduous dentition and thefirst permanent molars. London: Basle, Sons andDanielson, 1925.

2. Kasahara E,Yasuda E, Yamamoto A, Anzai M. Rootcanal systems of the maxillary central incisor. J Endod1990; 16: 158�161.

3. Kramer I R. The vascular architecture of the humandental pulp. Arch Oral Biol 1960; 2: 177�189.

4. Bellizi R, Hartwell G. Radiographic evaluation of rootcanal anatomy of in vivo endodontically treatedmaxillary premolars. J Endod 1985; 11: 37�39.

5. Vertucci F J, Seeling A, Gillis R. Root canalmorphology of the human maxillary second premolar.Oral Surg 1974; 38: 456-464.

6. Stropko J J. Canal morphology of maxillary molars:clinical observations of canal configurations. J Endod1999; 25: 446�450.

7. Zillich R, Dowson J. Root canal morphology of themandibular first and second premolars. Oral Surg1973; 36: 738�744.

8. Vertucci F J. Root canal morphology of mandibular premolars. J Am Dent Assoc 1978; 97: 47�50.

9. Skidmore A E, Bjorndal A M. Root canal morphologyof the human mandibular first molar. Oral Surg 1971;32: 778�784.

10. Melton D C, Krall K V, Fuller M W. Anatomical andhistological features of C-shaped canals in mandibularsecond molars. J Endod 1991; 17: 384�388.

Fig. 11 Thedevelopmentalanatomy of lower thirdmolars may be quitebizarre.

Fig. 10 Lower first molars may occasionally be foundwith two separate distal roots.

07p379-383.qxd 07/09/2004 12:36 Page 383


PRACTICE

Endodontics: Part 5Basic instruments and materials for root canal treatmentP. Carrotte1

In this part the basic endodontic instruments necessary for effective root canal treatment are described. The properties of,and manufacturer�s claims for, new instruments and techniques may be compared to these basic principles before they arepurchased and introduced to clinical practice. Having the correct instruments for different clinical situations may maketreatment both more efficient and more effective.

● A basic pack of all the endodontic instruments required must be available suitably sterilised toensure rapid efficient treatment.

● Modern radiographic techniques facilitate swift diagnosis and treatment procedures.● The development of endodontic instruments from reamers to greater taper nickel titanium

files is considered.● The importance of thorough and efficient irrigation with appropriate antiseptic agents is

discussed, together with the necessary precautions.

I N B R I E F

Many dental practitioners find it difficult toresist new gadgets, and there are an inordinatenumber made specifically for endodontics.New instruments and materials are frequentlysold with the promise of simplifying a tech-nique, shortening the time taken or evenincreasing the success rate. Unfortunately,these promises are often not fulfilled, and theresult may be cupboards in the practice con-taining unwanted endodontic armamentaria. Itwould be impossible to cover all the instru-ments and materials used in endodontics inone part, but it is hoped to mention most of thebasic equipment and discuss some of the neweritems. For continuity, some instruments will bedescribed in the relevant parts. The majority ofthe instruments and materials referred to in

this part are generic, and may be purchasedfrom most dental supply companies.

INSTRUMENT PACKA basic pack of instruments must be availablespecifically for routine root canal procedures.An example is given in Figure 1. A front surfacereflecting mouth mirror is preferable to preventthe double image of the fine detail in an accesscavity that occurs with a conventional mirror.Endolocking tweezers allow small items to begripped safely and passed between nurse andoperator. A DG16 endodontic probe is requiredto detect canal orifices. The excavator is longshanked, with a small blade to allow access intothe pulp chamber. The pocket-measuring probeis useful, a routine CPITN probe with clearly vis-

5













Fig. 1 An endodonticinstrument pack. Fromleft to right; frontsurface reflectingmirror; DG16endodontic probe;Western probe; CPITNprobe; endo-lockingtweezers; long shankexcavator; flat plastic,artery forceps,endodontic syringe;plus clean stand, filestand, measuringdevice, sterile cottonwool rolls and pledgets.





08p455-464.qxd 22/09/2004 10:22 Page 455

norms

Text Box


ible gradations is ideal. A furcation probe isuseful to check for the presence of furcationinvolvement. Other items usually included are aflat plastic, sterile cotton wool rolls, sterile cot-ton wool pledgets, artery forceps to grip a peri-apical radiograph and a metal ruler, or othermeasuring device that may be sterilized. Aclean-stand or other device such as the endo-ring is required to hold the endodontic instru-ments. Paper points are also required, and thesimplest method of storage and use is to pur-chase presterilized packs with five points ineach pack.

These instruments should be sterile whentreatment commences, and every possible effortmust be made to avoid contamination. Fewpractices will have an autoclave sufficientlylarge to take a metal tray with a lid that maycontain an entire set of sterile instruments. If anopen tray system is used, as illustrated in Figure1, it is useful to have all endodontic instrumentsin sterilized containers, such as the clean standor endodontic ring shown in Figure 2. Thisallows the instruments to be easily controlled,and accessed by both the operator and assistantduring treatment.

PATIENT PROTECTIONGlasses are needed to protect the patient�s eyes.Figure 3 also shows a waterproof bib beingworn, as the patient�s clothes must be protectedagainst accidental spillage of sodium hypochlo-rite, a frequent source of patient complaint oreven litigation.

RUBBER DAMRubber dam is essential in root canal treatmentfor three reasons:� To provide an operating field free from oral

contamination.� To prevent the patient swallowing or inhal-

ing root canal instruments or medicaments.� To give good visual access by retracting the

lips and tongue.

A basic kit for rubber dam equipment isshown in Figure 4. Details of this equipment,and of the techniques for the application of rub-ber dam, are given in the next part.

RADIOGRAPHIC EQUIPMENTLong-cone parallel radiography is a requirementfor endodontics,1 because it gives an undistortedview of the teeth and surrounding structures andis repeatable, thus allowing more accurate assess-ment of periapical healing. The bisecting angletechnique should no longer be employed. It is fur-ther recommended that rectangular collimation

PRACTICE


Fig. 3 A patient wearing safety glasses, a waterproofprotective bib and a rubber dam.

Fig. 6 a) A manual radiographic processing unit beingused and b) containing rapid developing and fixingchemicals.

Fig. 2 A selection of file holders.

Fig. 4 The rubber damequipment; clamps,dental floss, forceps,sheet, punch, frameand napkin.

Fig. 5 A film holder for takingparallel radiographs, incorporating acage device to fit over the rubberdam clamp.

a

b

08p455-464.qxd 22/09/2004 10:24 Page 456

PRACTICE


be fitted on all new radiographic equipment, andretro-fitted to existing equipment as soon as pos-sible. There are many beam-aiming devices avail-able to hold the x-ray film parallel to the tooth.Figure 5 shows an example of a popular holder,with a special cage attachment to fit over a rubberdam clamp.

A quick, reliable method of viewing radi-ographic images is essential for endodontics.Considerable time can be lost if such a system isnot available, especially on those occasions whenthe exposed film does not show the requireddetail. Practitioners using conventional radiogra-phy may wish to purchase an x-ray film processorwith rapid developing and fixing solutions, capa-ble of producing a radiograph for viewing inunder a minute; an example is shown in Figure 6.However, a modern automatic processor (Fig. 7)may be adjusted to deliver wet films in under twominutes. Films from both types of processorshould be carefully dried after viewing for accu-rate storage in the patient�s records.

A modern alternative involves the use of digi-tal radiography. A sensor plate, appropriatelysterilized and sealed, is used in place of the con-ventional film. The sensor may be either directlylinked to the computer, or resemble a conven-tional periapical film packet. The resultantimage is digitally processed and projected uponthe computer screen in a matter of seconds. Thequality of the image can be manipulated toenable greater clarity when reading the picture.For purposes of record keeping, the image maybe either dated, labelled and stored in the centraldatabase, or a hard copy printed for the patient�srecords. An example of such a system, and theimages produced, is shown in Figure 8.

The pre-operative radiograph contains muchinformation to assist the operator, which maynot be seen if the film is carelessly viewed. An x-ray viewer and some form of magnification areneeded to examine periapical films, and it is veryhelpful if glare from the light around the radi-ograph can be excluded (Fig. 9).

DEVELOPMENT OF HAND INSTRUMENTSFor many years the standard cutting instrumentshave been the reamer, K-type file and Hedstroem

file. These root canal preparation instrumentshave been manufactured to a size and typeadvised by the International Standards Organi-sation (ISO). The specifications recommendedare complex and differ according to the type ofinstrument. For most standardized instrumentsthe number refers to its diameter at the tip inone-hundredths of a millimetre; a number 10,for example, means that it has a tip diameter of0.10 mm. Colour coding originally denoted thesize, but now represents a sequence of sizes. Allthese instruments have a standard 2% taper overtheir working length.

Recent changes in both metallurgy andendodontic concepts have led to the introduc-tion of a range of new instruments which do notconform to these specifications. These aredescribed individually later and in Part 7. Theseinstruments have been widely adopted, andappear to give consistently better results in rootcanal treatment. However, the conventional 2%taper instruments are essential for the initialexploration of most root canals, for difficultprocedures such as bypassing separated instru-ments, and for the apical preparation of somedifficult canals.

Conventional �standardized� instruments aremade of steel, which may wear quickly in den-tine, and small size files may be regarded as dis-posable. Although some hand files are nowavailable in a nickel�titanium alloy, which ismore resistant to wear than ordinary steel, theincreased cost and inability to pre-curve has notled to their widespread use. The majority of thesemodern files are manufactured with a modifiednon-aggressive tip to prevent iatrogenic damageto the canal system, and improve performance ofthe instrument. Figure 10 shows the differentappearance of the principal types of theseinstruments.

K-type fileThese instruments were originally made from asquare or triangular blank, machine twisted toform a tight spiral. The angle of the blades orflutes is consequently near a right-angle to theshank, so that either a reaming or a filing action

Fig. 7 An automatic radiographic processor, with asimple device to bypass the drying cycle.

Fig. 8 An illustration of thecomputer screen produced by digitalradiography, enabling immediateviewing and manipulation of theimage The sensor plate or �film� maybe either loose, resembling aconventional periapical radiographicfilm, which must be inserted into themachine for processing, or linked bycable to the processor as in b).

a b

Fig. 9 A radiographic viewerdesigned to eliminate extraneouslight and magnify the image.

Fig. 10 Conventional handinstruments; top � reamer with redstop; middle - Hedstroem file withblack stop; bottom - K-flex file withyellow stop.

08p455-464.qxd 22/09/2004 15:56 Page 457

PRACTICE


may be used. The K-type file has been subject tocontinuous development. The K-flex file is madefrom a rhomboid or diamond shaped blank. Theacute angle of this shape provides the instru-ment with two sharp blades and the narrowerdiameter allows greater flexibility in the shaftthan a conventional K-file. The manufacturersclaim that more debris is collected between theblades and therefore removed from the canalthan with a standard K-file. The Flex-o-fileemploys a more flexible type of steel. It does notfracture easily and is so flexible that it is possibleto tie a knot in the shank of the smaller sizes.

The latest developments in file design haveseen a move away from the ISO standard 2%taper to files with increasing tapers of up to 12%,made in a nickel-titanium alloy. Although mostof these new developments are used with anelectric motor, hand files of greater taper areavailable. These are illustrated in Figure 11.Their use is described in Part 7.

Although most K-type files were originallyused with an �in-out� circumferential filing tech-nique, the �balanced-force� technique, describedin Part 7, is now considered the manipulationmethod of choice.

Hedstroem fileThe Hedstroem file is machined from a roundtapered blank. A spiral groove is cut into theshank, producing a sharp blade. Only a true fil-ing action should be used with this instrumentbecause of the angle of the blade. There is astrong possibility of fracture if a reaming actionis used and the blades are engaged in the den-tine. The Hedstroem file is useful for removinggutta-percha root fillings.

Other hand filesDifferent types of hand file have been introducedfrom time to time with varied structure and cut-ting action. The Unifile and Helifile were modifi-cations of the Hedstroem design. The Mani Flarefile is made from a triangular blank, and featuresa greater taper than conventional 2% files. It isessential when considering the use of new filedesigns that the operator understands the basicprinciples of canal preparation, and comparesand contrasts the properties with the file manipu-lation technique currently being used.

ReamerThe reamer is constructed from a square or trian-gular blank, machine twisted into a spiral butwith fewer cutting flutes than a file. The reamerwill only cut dentine when it is rotated in thecanal; the mode of action described for its use isa quarter to a half turn to cut dentine, and with-drawal to remove the debris. The stiffness of aninstrument increases with each larger size, sothat larger reamers in curved canals will tend tocut a wider channel near the apical end of theroot canal (apical zipping). Considerable damagemay be caused to a root canal by the incorrectuse of a reamer, and their routine use is nolonger recommended.

Power-assisted instrumentsHandpieces providing a mechanical movementto the root canal cutting instrument have beenavailable since 1964. Their function was prima-rily a reciprocating action through 90° and/or avertical movement, according to the design andmake. Because steel files do not have the flexi-bility necessary for rotary movements in acurved canal without damaging the canal con-figuration, these instruments were never reallyacceptable in endodontic practice.

A totally new concept in canal preparationcame with the development of sonic and ultra-sonically activated endodontic handpieces.Much research took place into the mode of actionand effectiveness of these machines. It was gen-erally agreed that while the sonic machines weremore effective at hard tissue removal, the ultra-sonic machines were more effective in irrigation.The piezo-electric machines were found to bemore effective than the magnetostrictive. Thelatter also generated more heat, and irrigationwith effective quantities of sodium hypochloritewas found to be difficult.

The ultrasonic action causes acoustic micro-streaming of the irrigant, intensive circular fluidmovement carried right to the tip of the instru-ment, found to be very effective at canaldebridement. This effect is reduced, however,when the file is constrained by the canal wall.The main use of these instruments today is inirrigation and debridement, using a freely oscil-lating file in a sodium hypochlorite filled canal,after thorough mechanical canal shaping.2

Fig. 11 A pack of hand files ofgreater taper, 12% taper (blue),10% (red), 8% (yellow) and 6%(white).

Fig. 12 A low-speed, high-torque motor required for usewith nickel-titanium rotary instruments.

Fig. 13 An EDTA paste which will usually be picked up oneach instrument before use.

08p455-464.qxd 22/09/2004 10:26 Page 458

PRACTICE


However, the development of nickel-titaniumalloy for endodontic instruments has allowedthe concept of an engine driven endodonticinstrument to be fully explored. The total flexi-bility of this alloy, and the use of radial lands onthe cutting flutes to keep the instrument centredin the canal, permit controlled cutting of thedentine walls. Most major manufacturers havedeveloped a nickel-titanium rotary system.Lightspeed, Profiles, GT Rotary files, FlexMaster,Quantec system, Hero, K3, Protaper, and nodoubt more will appear before this book is evenpublished. It would not be possible to describeeach of these fully, but the basic concepts arepresented here, with a general description oftheir use being given in Part 7.

The systems will generally conform to one ofthree patterns. � The system may have a standard ISO tip size

sequence, with the instruments being manu-factured with an increased taper, usuallyeither 4% or 6%.

� The system may be presented with a singletip size, but with the sequence of file sizeshaving an increased taper of up to 12%. Inorder to accommodate this taper in a narrowroot canal, the diameter of the instrument isusually limited to 1 mm, giving quite a shortfunctional blade in the greater tapers.

� Both of these new developments may becombined into one system.

A low-speed, controlled-torque motor is nec-essary when using these instruments, as illus-trated in Figure 12.

Irrigation and lubrication materials It is generally accepted in endodontic practicethat sodium hypochlorite is the most suitablesolution for irrigation of the root canal system.Normal household bleach is approximately 5.5%sodium hypochlorite solution, and this may bediluted with purified water up to five times to theoperator�s preference. Research has shown thatthe antibacterial effect is the same for a 0.5%and a 5.0% solution.3 However, the greater thedilution the less effective is the solution at dis-solving organic debris in the root canal system.

Great vigilance is essential when using sodi-um hypochlorite, and practitioners must beaware of the risks and dangers involved in itsuse. Irrigation under pressure may force thesolution through the apical foramen into theperiradicular tissues, which may result in arapid, painful and serious inflammatoryresponse. The patient will be extremely dis-tressed, and little can be done to relieve the situ-ation which may take several days to resolve.Cases have also been reported where excesspressure on the syringe has resulted in the nee-dle coming loose and hypochlorite sprayingover the patient, operator and assistant. Protec-tive goggles are essential for the patient and allstaff. Clothing should also be protected. Thedefence societies have received claims from iratepatients for damaged clothing following root

canal treatment. The practitioner must haveappropriate risk assessment procedures in placewhen such materials are incorporated into theirclinical practice.

Chlorhexidine solution 0.2% has a similarantibacterial action, but will not dissolve theorganic debris found in parts of the canal systeminaccessible to hand instrumentation, such aslateral canals, fins and apical deltas. However,the substantivity associated with this irrigantmeans that it will adhere to dentine, therebyexhibiting a prolonged antibacterial activity.Although chlorhexidine may not be quite aseffective as sodium hypochlorite, its use shouldnot be dismissed.

Researchers are constantly seeking improvedmethods of cleaning root canals; reports haveappeared recently relating to the use of electro-activated water as an irrigant,4 and the use ofhigh frequency electric current.5 These and oth-ers may prove interesting developments in rootcanal preparation and irrigation.

EDTA paste (Ethylenediamine tetra-aceticacid) is a chelating agent which softens the den-tine of the canal walls and greatly facilitatescanal preparation (Fig 13). EDTA solution maybe used as an irrigant at the end of the canalpreparation phase to assist removal of the smearlayer prior to placement of an intervisit dressing,or obturation.

BursSeveral types of bur may be required for rootcanal treatment. Some of these are describedbelow, and shown in Figure 14.

Cutting an access cavity It is generally accepted that high speed bursshould be used to gain access and shape the cav-ity. A diamond or tungsten carbide tapered fis-sure bur is used for initial penetration of the roofof the pulp chamber. A tapered safe-ended dia-mond or tungsten carbide bur is then used toremove the roof of the pulp chamber withoutdamaging the floor.

Location of canalBurs should only be used as a last resort to locatea sclerosed canal because of the danger of perfo-ration. Small round burs are used; the standardlength is usually too short but longer shank bursare available. Specially designed ultrasonic tipsmay also be used to remove secondary dentine,assist in the identification of canal orifices andin shaping the canal orifice during preparation.The use of ultrasonic tips has become morewidespread with the introduction of a widerrange of fittings to different piezo-electronicmachines. Figure 15 shows the diamond coatedCPR® tips, designed for troughing and chasingsclerosed canals, and the BUC® tips, with vari-able grades of diamond grit for refining accesscavity walls and line angles, removing obstruc-tions and cutting around posts. As with allinstruments and materials, the manufacturer�sinstructions and guidance should be carefully

Fig. 14 Some of the burs specificallymanufactured for endodontictreatment; a safe-tipped access bur;a long-shanked round bur; a swan-necked bur; a Gates-Glidden bur.

08p455-464.qxd 22/09/2004 10:27 Page 459

PRACTICE


followed or these delicate diamond tips may bedamaged. It is generally wise to use them with alow power setting, and to ensure that they are incontact with dentine before activating the piezo-electric unit.

Canal preparationThe use of rotary cutting instruments in a stan-dard handpiece is condemned because of thedanger of fracture of the instrument or perfora-tion of the root canal. The exception to this ruleis the Gates�Glidden bur, which has a safe-ended tip. In addition, the site of fracture, if itdoes occur, is almost always near the hub so thefractured piece is easily removed. In the past thisbur has been recommended for initial flaring ofthe coronal portion of the canal. This may nowbe carried out in a more controlled manner witha nickel-titanium orifice shaper. The Gates�Glidden bur may also be used to make post spaceand to remove gutta-percha from the canal.Gates�Glidden burs are manufactured in sixsizes; their use is described in Part 7.

Measurement of working length There are two established methods of assessingthe working length of a root canal: one by radi-ography and the other with the use of an elec-tronic device apex locator (Fig. 16). Both meth-ods will be described in Part 7.

Once the working length has been confirmed,the individual preparation instruments must beaccurately marked to length accordingly. Thereare many different gadgets available for transferof the working length; the author prefers thedevice shown in Figure 17. There are also differ-ent stops for the instrument, the most popularbeing rubber or silicone stops. These shouldalways be placed at right angles to the shank ofthe instrument. Ideally the stops should be eithernotched, or pear shaped, so that in curved canalsthe notch or point of the pear may be directedtowards the curve placed in the instrument.

SterilizationAny instrument which is placed in the root canalshould be sterile, for two reasons. Firstly, toprevent the introduction to the root canal sys-tem of extraneous microorganisms, which mayseverely compromise treatment, for examplepseudomonas.6 Secondly, if instruments anddevices were to be used on different patients, toprevent cross-infection between patients. Bacte-

ria, viruses, fungi and prions may contaminateinstruments and research has shown that someof these may not be destroyed by any method ofsterilization.7 Figure 18 illustrates this dramati-cally. Concern has been raised over the steriliza-tion of other items of dental equipment as well.8

Under the Medical Devices Directive, the man-ufacturer of any dental instrument has an obli-gation to inform the end-user (ie the dentist)how their product should be decontaminated. Itis essential that this guidance is followed. What-ever may be written in this and other texts maybe superseded at any time. Dentists shouldtherefore ensure that they are familiar with andconform to the manufacturer�s instructions. Atpresent, some endodontic instruments aremarked with the symbol shown in Figure 19indicating that they are single use instruments.It is assumed that all manufacturers will shortly follow this Medical Devices Directive.

It may, however, be necessary to sterilizeinstruments for further treatment of the samepatient on a subsequent occasion when cross-infection control would not be a problem. Afteruse, instruments must be cleaned as soon as pos-sible to remove debris which harbours and pro-tects microorganisms. Cleaning is carried out byscrubbing in warm water and detergent, althoughthe debris may be first removed from most rootcanal instruments by stabbing them into asponge. The best method of cleaning is to placethe instruments into an ultrasonic bath. The cavi-tational effects of ultrasonics will dislodge debrisfrom places which are inaccessible to normalcleaning. When the instruments are clean theymust be sterilized in an autoclave. Microorgan-isms are destroyed at lower temperatures and in ashorter period in moist heat as all biological reac-tions are catalysed in water. The disadvantages ofautoclaving are that metal instruments tend tocorrode and sharp instruments are dulled.

Barbed broachThis instrument has sharp rasps pointingtowards the handle. They may be used toremove the contents of the root canal beforecommencing shaping procedures. A vital pulpmay be extirpated when carrying out electiveendodontic procedures, or when treating a toothwith an irreversible pulpitis, by introducing thebarbed broach deep in the canal, twisting it aquarter to a half turn, and withdrawing, asshown in Figure 20.

Fig. 16 An electronic apex locator.

Fig. 17 A device forsetting instrumentsat the correctworking length

Fig. 15 (a) CPR® ultrasonic tips, nowavailable to fit different piezo-electronic machines. (b) Also shownare KiS tips for periradicular surgery.

a b

08p455-464.qxd 22/09/2004 10:28 Page 460

PRACTICE


Spiral root canal fillers Spiral root canal fillers are seldom used in mod-ern endodontics. Their main use is for the inser-tion of calcium hydroxide into the root canal.When a spiral filler is required, the blade type ispreferred by the author, as this is the least likelyto fracture. It is essential to ensure that the sizeselected fits loosely and passively to the requireddepth before the instrument is rotated in the rootcanal (Fig. 21).

ROOT CANAL FILLING MATERIALSGutta-perchaGutta-percha is the most commonly used mate-rial for the obturation of the prepared root canalsystem. Standardized gutta-percha points corre-spond to the ISO sizing system with a 2% taper.Various other shapes are now available to com-plement the recently introduced increased taperfiling systems (Fig 22). Gutta-percha is the driedresin of the Taban tree, and exists in two forms.Alpha phase is the natural form, but when heat-ed and cooled the beta-phase results. This latteris normally used for root canal filling points.

Gutta-percha points in fact contain onlyabout 20% gutta-percha. The major component

is zinc oxide (up to 75%), with the remaindercomprising various resins, waxes and metallicsulphates to the specific manufacturer�s formula.

Sealers/cementsRoot canal sealers play an important role in theobturation of the prepared root canal system, asdescribed in Part 8. Although many proprietaryproducts are available (Fig. 23), they may gener-ally be divided into three groups, according totheir main constituents: eugenol, non-eugenoland medicated.

EugenolThe eugenol-containing group may be dividedinto sealers based on the Rickert�s formula(1931) and those based on Grossman�s (1958)(Table 1). The essential difference between thetwo groups is that Rickert�s contains precipitat-ed silver and Grossman�s has a barium or bis-muth salt as the radiopacifier. The disadvantageof Rickert�s sealer is that the silver will staindentine a dark grey. One of the most widelyused sealers in this group is Tubliseal, a two-paste system and, consequently, simple to mix;it does not contain silver. Tubliseal EWT(extended working time) is preferred.

Non-eugenol sealersSome sealers are manufactured with a calciumhydroxide base instead of zinc oxide/eugenol,

Fig. 18 Illustrations from the work on decontamination of endodontic instruments by Dr Andrew Smith, Glasgow: a) photomicrograph (x16) of an unusedendodontic file; b) photomicrograph (x16) of a used instrument after sterilization; c) SEM (x500) of the file shown in illustration b.

a b c

Fig. 20 During root canal treatmentof a tooth diagnosed as having anirreversible pulpitis, the vital pulp hasbeen extirpated on a barbed broach.

Fig. 21 Spiral fillers may fracture if the size is notverified passively before rotating in the canal.

Fig. 19 The symbol indicatinginstruments intended for single useonly.

Fig. 22 Some of the different gutta-percha points:standarized; greater taper; 04 and 06 taper; feathertipped.

08p455-464.qxd 22/09/2004 10:29 Page 461

PRACTICE


for example Sealapex. This is promoted as havinga therapeutic effect, although there has been lit-tle reported on this in the endodontic literature.It has been shown, however, that the calciumhydroxide is prone to leakage,9 which may resultin unwanted voids in the seal.

Other sealers are manufactured that contain awide variety of chemicals. AH+ is an epoxy resinbase with a bisphenoldiglycidyl ether liquid. Ithas a long working time and seals well to den-tine. The original AH26 initially caused a severeinflammatory response, which subsided aftersome weeks, but AH+ is far more biocompatible.Diaket is a polyketone and is presented as a finepowder and thick viscous liquid. The settingtime is 8 minutes on the mixing pad and some-what quicker in the root canal. A glass ionomercement, Ketac-Endo, is available, which has arelatively low toxicity.

A more recent addition to this group isRoekoseal, a silicone polymer. Although initialexperience of this material is favourable, therehas been little published on several of theserecent materials, and the prudent clinician maywish to await the results of extended clinical trials before adopting these into their practice.

MedicatedThe current thinking is that provided the prin-ciples of root canal preparation and filling areobserved, there is no justification for the use oftherapeutic sealers. The active ingredient in themajority of medicated sealers is paraformalde-hyde, which is usually accompanied by a corti-costeroid. Figure 24 shows a medicolegal casewhere excess medicated sealer entered the infe-rior dental canal, causing permanent nervedamage with paraesthesia of the lip and softtissues.

Mineral trioxide aggregateMineral trioxide aggregate (Fig. 25) is a com-pound consisting of mineral oxides, (tricalciumsilicate, tricalcium oxide, silicate oxide andtraces of other mineral oxides), developed firstby Mahmoud Torabinejad and co-workers atLoma Linda University.10 Although originallydeveloped as a root-end filling material duringperiradicular surgery, researchers across theworld have reported positive results when thematerial is used for the repair of perforations, asa pulp capping agent, and to induce apical clo-sure of immature roots. The superb sealing abili-ty, marginal adaptation and biological compati-bility of the material appear to make thismaterial the sealant of choice for any communi-cation between the root canal system and theexternal surface of the tooth. The material iscontinually being refined, and the latest producthas some oxides removed to produce a white,rather than grey, powder. MTA is a difficultmaterial to manipulate, having the consistencyof wet sand. Methods of placement are describedin Part 11.

Root canal filling instrumentsSpreadersCold lateral compaction using gutta-percharequires either long-handled or finger spreaders(Fig. 26). These have a long, tapered shank witha sharp point. The instrument is used to compactgutta-percha laterally against the walls of theroot canal and provide a space for the insertionof further gutta-percha points. There are severalsizes available, and these are selected accordingto the canal size and the size of the gutta-perchapoint. The choice of long-handled spreaders orfinger spreaders depends on personal preference.The advantage of finger spreaders is that lessforce can be used, and this reduces the risk ofroot fracture.

Heat carriersThe application of heat to the gutta-percha fill-ing permits improved lateral and verticalcompaction of the softened material. Ordinaryhand and finger spreaders are not designed forthis purpose, but the instruments illustrated inFigure 27 may be used. They are of varioussizes, and have both a pointed tip for lateralspreading, and a flat tip for vertical compaction.

The instrument shown in Figure 28 is a Sys-tem B, for the controlled and precise application

Table 1 Grossman�s sealer

PowderZinc Oxide 42.0%

Staybelite resin 27.0%

Bismuth subcarbonate 15.0%

Barium sulfate 15.0%

Sodium borate (anhydrous) 1.0%

LiquidEugenol 100%

Fig. 24 A medicolegal case where aformaldehyde containing root canalsealer has been extruded into theinferior dental canal, causingparaesthesia of the lip.

Fig. 25 Mineral Trioxide Aggregateis commercially available as Pro-Root.

Fig. 23 A selection ofroot canal sealers.

08p455-464.qxd 22/09/2004 10:30 Page 462

PRACTICE


of heat to the gutta-percha filling. Figure 29shows an Obtura machine, used to deliver heatedgutta-percha directly to the root canal. The useof these and other similar machines is describedin Part 8.

MagnificationWhen asked why endodontics is a difficultsubject, undergraduate and postgraduate stu-dents alike frequently reply that it is becausethey cannot see what they are doing. There isno doubt that magnification of the pulp cham-ber greatly assists in finding and accessingnarrow canal orifices, and many practitionersnow routinely use loupes, as seen in Figure 30.This one purchase has made huge improve-ments in the quality and ease of endodontictreatment for many practitioners. Indeed, the improved vision gained from the use ofloupes improves all aspects of general dentalpractice, not just endodontics. The patient inthe illustration is merely undergoing a routineexamination.

However, specialist practitioners, and somegeneralists, are moving to the use of surgicalmicroscopes, as seen in Figure 31 where it isbeing used by a relatively new member of staffin training, who was seeking, and found, asclerosed canal in an upper incisor.

Fig. 26 Cold lateralcompaction may becarried out with eitherfinger spreaders orlong-handledspreaders.

Fig. 28 The System B heat source for controlled warmgutta-percha techniques.

Fig. 29 The Obtura 11 system for injecting heat-softened gutta-percha into the root canal.

Fig. 27 Machtou heatcarrier/pluggers forwarm lateral andvertical compaction.

Fig. 30 The use ofmagnifying loupes isincreasing inrestorative dentistry.

Fig. 31 A surgicalmicroscope may beessential for some oftoday�s intricateendodontic procedures.

08p455-464.qxd 22/09/2004 10:32 Page 463

PRACTICE


1. National Radiographic Protection Board. GuidanceNotes for Dental Practitioners on the safe use of x-rayequipment. 2001 Department of Health, London, UK.

2. Cameron J A. The synergistic relationship betweenultrasound and sodium hypochlorite: a scanningelectron microscope evaluation. J Endod 1987; 13: 541�545.

3. Byström A, Sundqvist G. Bacteriological evaluation ofthe effect of 0.5% sodium hypochlorite in endodontictherapy. Oral Surgery, Oral Medicine, Oral Pathology1983; 55: 307�312.

4. Solovyeva A M, Dummer P M. Cleaning effectivenessof root canal irrigation with electrochemicallyactivated anolyte and catholyte solutions: a pilotstudy. Int Endod J 2000: 33: 494�504.

5. Haffner C, Benz C, Folwaczny A, Mech A, Hickel R.High frequency current in endodontic therapy; an

in-vitro study. J Dent Res 1999; 78: 117.6. Ranta K, Haapasalo M, Ranta H. Monoinfection of root

canals with Pseudomonas aeruginosa. Endod DentTraumatol 1988; 4: 269�272.

7. Smith A J, Dickson M, Aitken J, Bagg J. Contaminateddental instruments. Journal of Hospital Infection 2002(in press).

8. Lowe A H, Bagg J, Burke F J T, MacKenzie D, McHughS. A study of blood contamination of Siqvelandmatrix bands. BDJ 2002; 192: 43�45.

9. Tronstad L, Barnett F, Flax M. Solubility andbiocompatibility of calcium hydroxide-containingroot canal sealers. Endod Dent Traumatol 1988; 4: 152�159.

10. Torabinejad M, Hong C U, McDonald F, Pitt Ford T R.Physical and chemical properties of a new root-endfilling material. J Endod 1995; 21:349�353.

British Dental Journal, 21 September 1954

Letter to the Editor

Sir, Is there a connexion between the sucking of peppermints, and the extremely rapid type of

caries sometimes seen in adult patients? I am convinced that there is, having observed it forsome years in regular patients, hitherto fairly free from caries, and entirely free from cervicalcaries, who, wishing to give up smoking, have taken to eating peppermint sweets — especiallyone particular brand. The resultant cervical caries, even in a few months, can be alarming. Justas quickly, by stopping the use of peppermint, the mouth seems to resume its original cariesimmunity, although the consumption of other forms of confectionery is not limited. If theseobservations of mine are correct, peppermint would seem to be an unfortunate choice offlavouring for a toothpaste!

R. DunstanBr Dent J 1954

Fifty years ago today

08p455-464.qxd 22/09/2004 10:32 Page 464

shilpa

Rectangle

BRITISH DENTAL JOURNAL VOLUME 197 NO. 9 NOVEMBER 13 2004 527

PRACTICE

Endodontics: Part 6Rubber dam and access cavitiesP. Carrotte1

Rubber dam is easy to apply once the basic components and principles are understood. An efficient and well-trained dentalnurse will greatly facilitate the application procedure. Although preparation of the access cavity may be commenced beforerubber dam is applied to enable anatomical landmarks to be followed, the rubber dam should be placed as soon as possiblewith adequate protection against contamination of the access. The access cavity reflects the shape of the pulp chamber,modified by the angle of instrument approach.

● Rubber dam is essential for effective isolation of the root canal and operating field from salivarybacteria, as well as protection of the airway.

● Only a very small number of rubber dam clamps are required for the efficient application ofrubber dam, which must be supported by a well-trained dental nurse.

● Success in modern endodontic treatment may be dependent upon a well-designed accesscavity to permit straight-line access to all the main root canals.

I N B R I E F

RUBBER DAMThe use of a rubber dam is almost mandatory inmodern endodontic practice for three reasons.

Firstly, it provides an aseptic operating field,isolating the tooth from oral and salivary con-tamination. It cannot be stressed enough thatcontamination of the root canal with salivaintroduces new microorganisms to the rootcanal which may prolong treatment and reduceprognosis.

Secondly, rubber dam facilitates the use of thestrong medicaments necessary to clean the rootcanal system.

Finally, it protects the patient from the inhala-tion or ingestion of endodontic instruments, asshown in Figure 1.

Practitioners may also be advised to developtheir rubber dam skills for another reason.Research has shown1 that rubber dam used dur-ing routine conservation procedures reducesaerosol contamination and cross-infection by upto 98.5%.

Research has also shown that patients do notdislike the use of rubber dam,2 and the authorhas never had a single patient request itsremoval once the reasons for its use have beenexplained. It may be particularly helpful toexplain to the patient that the rubber dam is nec-essary to isolate the operating area in exactly thesame way as a surgical drape is essential for sim-ilar invasive medical procedures, where bacterialcontamination may have a profound effect onthe outcome. Indeed, refusal to accept a rubberdam may preclude the prescription of endodon-tic therapy. If an endodontic instrument is

inhaled, a medicolegal allegation of negligencemay be impossible to defend, even if the patienthad appeared to accept the risk. A practitionershould never do anything to a patient which heor she knows to be wrong, and a patient may notsign away their rights in law.

With a little practice, an understanding of thebasic principles, a well organised surgery and awell-trained dental nurse, a single tooth can beisolated in only a few seconds.

6













Fig. 1 An endodontic instrument has been inhaled due toa lack of airway protection.





09p527-534.qxd 27/10/2004 09:23 Page 527

Rubber dam sheetsMost manufacturers supply rubber dam in threethicknesses or grades, for different applications.Depending upon the manufacturer, these will bedesignated either light, medium and heavy, ormedium, heavy and extra-heavy. The thinnest ofthe three is more prone to splitting, and the heav-iest more difficult to manipulate, which meansthat the most widely used is the middle grade. Thesheets are presented in a variety of colours, somebeing impregnated with peppermint and otherscents to disguise the smell of the rubber. The feelof rubber against the skin may be countered bysimply placing a gauze underneath the dam.

A pack of latex free dam is also necessary forpatients with latex allergies. This materialappears slightly stiff at first but stretching thesheet a few times makes it easier to handle.

Rubber dam punchMuch of the equipment for rubber dam has beenrationally modified. The revolving plate on theold punch was rarely used, as a single size holewill really fit all teeth. When the table wasmoved it frequently led to eccentric wear of thepin, which then did not cut a clean hole. The

defect in the cut may cause the dam to splitwhen stretched out. The new rubber dam punch-es are single table (Fig. 2) and should always cuta clean hole. If they do not, they should bereturned to the supplier.

Rubber dam stampThis is another piece of equipment now largelysuperseded. For single tooth isolation, a holepunched 2 cm diagonally from the middle of thesheet gives universal dam. The hole is simplyorientated to the quadrant under treatment. Formultiple isolation, it is preferable to hold thedam against the teeth to be isolated, and markthe centre of each tooth with a pen, as shown inFigure 3. The holes will then be punched inaccordance with the patient�s dentition and notwith an arbitrary stamp.

Rubber dam forcepsThe rubber dam forceps are used to carry theclamp to the tooth. The most frequently reportedproblem with rubber dam is that when the clamphas been expanded and placed on the tooth, theforceps are stuck in the clamp and cannot beremoved! This is because the grooves in the tipsof the forceps are too deep. These should bemodified with a stone or sandpaper disc so thatthey just engage the clamp, but slide off easily.Most forceps have a second groove slightly dis-tant from the tip, which may be used to removethe rubber dam clamp without re-engaging theholes (Figs 4 and 5). There are several designs offorceps, and they may be employed with eitheran over-hand or under-hand grip � experimen-tation will reveal the most comfortable.

Fig. 3 For multipleisolation, the position ofthe holes to be punchedmay be marked byholding the rubber damagainst the teeth.

PRACTICE

528 BRITISH DENTAL JOURNAL VOLUME 197 NO. 9 NOVEMBER 13 2004

Fig. 2 A modern singletable rubber dam punch.

Fig. 5 a) The second groove for removal of the rubberdam clamp, as shown in b).

Fig. 4 The tips of the rubber damforceps on the right have beenmodified for ease of use.

a b

Second groove

First groove

09p527-534.qxd 27/10/2004 09:25 Page 528

Rubber dam clampsThere is a vast range of shapes and sizes of rub-ber dam clamps, supposedly to suit every possi-ble tooth and situation. In fact, this merely caus-es confusion, as an ill-fitting clamp may be quiteunsatisfactory, and dislodge during treatment.When properly fitted, a clamp should have four-point contact with the tooth. If not, it will eitherrock back and forward or dislodge completely.

Clamps are described as being either �active�,where the jaws slope downwards and positivelyslide into cervical undercuts, or �passive� whenthey tend to remain where placed. They may alsobe either winged or wingless, depending uponthe chosen method of application.

The size 8A clamp is described by the manu-facturers as a �universal retentive molar clamp�.

It is an active clamp, and fits every molar tooth,even when these are quite broken down. Theauthor would suggest therefore that all the otherdesigns merely confuse the issue, and until theoperator is very experienced only this clamp isused for all molar teeth. Likewise, the size 1 fitsvirtually all premolars (Fig. 6). If passive clampsare preferred size 0 or 00 are suitable for premo-lars, although they will not be as retentive.Rather than place aggressive clamps on anteriorteeth, it is usually kinder to use interproximalwedges, either pieces of rubber dam or a com-mercial product such as �Wedgets� (Fig. 7). It isoften easier to isolate several anterior teeth, giv-ing a clear operating field.

Occasionally, a clamp may be dropped in thepatient�s mouth, or may fracture across the bowas seen in Figure 8, during application. All rub-ber dam clamps should be protected with alength of dental floss, about 50 cm, threadedthrough the holes on either side. It is not neces-sary for this to be wrapped around the clamp aswas described in some early restorative text-books. Indeed this should not be done since,once the clamp is in place above the rubber damsheet and technically outside the mouth, thefloss should be cut and withdrawn. If not it mayact as a wick, drawing saliva into the operatingfield, or taking medicaments down into themouth. Small voids around the dam may besealed with a caulking agent such as Oraseal orCavit (Fig. 9).

Fig. 9 a) A caulking agent which may be used to seal voids around the rubber dam that may allowsalivary contamination, as shown in b).

PRACTICE


Fig. 7 Wedgets may be used in place of clamps foranterior teeth.

Fig. 6 Universal molar and premolar clamps,demonstrated on a phantom head. a) A wingless molarclamp (W8a). b) A winged premolar clamp (1)

a b

Fig. 8 Rubber dam clamps should always be protectedwith a length of dental floss in case they either fracture,as shown here, or are dropped in an unprotected mouth.

a b

09p527-534.qxd 27/10/2004 09:26 Page 529

The rubber dam frameThe old Ash frame, with its �butterfly� retainers,has largely been replaced by plastic or metalframes with sharp points or pins. It should benoted that the majority of these retentive pointsslope backwards, and the frames are designed tobe placed under the rubber dam (Fig. 10). Itseems to be much easier to place the framebeneath the dam and simply stretch the sheetover the points than the other way round. Inaddition, the tension in the sheet can be bettercontrolled, particularly relevant when workingin a situation where the clamp may be lessretentive than normal.

For comfort, most patients appreciate a smallpiece of gauze placed between the rubber andtheir skin, and some practitioners place a prop(an old McKesson anaesthetic type) between theteeth on the non-working side to relieve thepatient�s muscle tension.

APPLICATION TECHNIQUESA well-trained dental nurse and a well organisedsurgery, are essential for efficient application ofthe rubber dam. If a tray is prepared with readypunched sheets, and sterilised clamps alreadyflossed, application can be performed in a matterof seconds.

There are three standard methods of applica-tion, described and illustrated here.

Winged techniqueThe appropriate winged clamp (8A for molars, 1for premolars) is selected and flossed. The rubberdam is punched and aligned with the quadrant tobe treated. The clamp is held in the forceps andretained with the ratchet. The hole in the rubberis stretched across the wings of the clamp, posi-tioning the bow of the clamp towards the back ofthe arch. All this may be done by the dental nursewhile the dentist is otherwise occupied, perhapsadministering the local anaesthetic. The nursethen holds the top of the sheet to improve visionfor the operator, who simply places the clamponto the tooth to be treated (Fig. 11). A flat plasticinstrument is then used to push the rubber off thewings, and the frame and gauze are applied. Thefloss may then be removed and the seal verifiedor adjusted as necessary.

Wingless techniqueThe appropriate wingless clamp (W8A formolars, W1 for premolars) is selected andflossed. The rubber dam is punched and alignedwith the quadrant to be treated. The clamp, heldin the forceps and retained with the ratchet, isplaced securely on the tooth. One advantage ofthis method is that the opportunity now exists toverify the fit of the clamp before proceeding(Fig. 12). The rubber dam is now held in bothhands, and the index fingers used to stretch outthe punched hole, which is slipped over the bow

PRACTICE


Fig. 10 The rubber dam frame may be easier toplace beneath the rubber sheet.

Fig. 11 The winged technique. The hole in the rubber sheet has been stretched over the wings of theclamp a), which is then fitted to the tooth b). The rubber is pushed off the wings, and the seal verified.

a b

Fig. 12 The wingless technique. a) The flossed clamp has been placed on the tooth, and b) the rubber is stretchedover the bow and pulled forward around the clamp.

a b

09p527-534.qxd 27/10/2004 09:27 Page 530

PRACTICE


of the clamp and pulled forward and down ontothe tooth. Again, the nurse may hold the top ofthe sheet to improve vision for the operator. Theframe and gauze are applied, the floss removedand the seal verified or adjusted as necessary.

Rubber firstThe third method taught in some centres involvesthe dental nurse to a greater extent. The dentiststretches out the rubber and places the hole overthe tooth in question, holding it down on eachside with light finger pressure. At the same timethe dental nurse picks up the flossed clamp in theforceps and places it over the tooth, retaining thedam in place (Fig. 13). Once again, the frame andgauze are applied, the floss removed and the sealverified or adjusted as necessary.

Anterior teethAs stated previously, in a relatively intact arch itis easier to isolate several anterior teeth. Dentalfloss should be used first to verify that the con-tacts are clear and that the rubber dam will passthrough. The rubber sheet is held against theteeth and the centre point marked of those teethto be isolated. Holes are punched at these points,and the rubber dam is then applied to the teeth.Taking a leading edge of rubber through thecontact � �knifing through� � makes applicationrelatively simple, or dental floss may be used todraw the rubber through a difficult contact.Once in place the selected wedges are applied.

Everting the marginsIf the rubber dam is lying on the tooth surface itmay allow leakage of saliva, a problem particu-larly when the dam has been applied duringadhesive restorative procedures, but also withendodontics. The margin should be everted intothe gingival crevice as shown in Figure 14. Theoperator stretches the rubber away from thetooth whilst the assistant directs a stream ofcold air from the triple syringe onto themucosa. With the use of a flat plastic instru-ment the margin of the rubber dam may betucked into the gingival crevice, providing atight seal.

Alternatively, some operators apply floss liga-tures, as shown in Figure 15, using a flat plastic

Fig. 13 The rubber first method.The operator is holding the sheetover the tooth whilst the assistantplaces the clamp to secure it inplace.

Fig. 14 a) The rubber dam is lying on the toothsurface and may allow leakage. It should beeverted into the gingival crevice by

b) stretching the rubber away from the toothand drying the mucosa with a stream of cold air,before

c) using a flat plastic instrument to tuck therubber into the crevice.

a b c

Fig. 15 Alternatively, floss ligaturesmay be used to hold the rubber damin the gingival crevice. Ligatures willbe applied to each tooth undertreatment.

09p527-534.qxd 27/10/2004 09:28 Page 531

PRACTICE


to push the floss above the cingulum, and tying aknot securely on the labial aspect of the tooth.

DIFFICULT SITUATIONSThere are a few situations where the applicationof rubber dam may present difficulties, althoughthe cautious clinician may consider whether rootcanal treatment is then either appropriate, ormay be severely compromised.

The broken down toothThe broken down tooth may be tackled in a vari-ety of ways. Many molar teeth with large defi-ciencies may have rubber dam applied, provid-ing the right clamp is used; the authorrecommends a W8a (see Fig. 2). With an appro-priate length of floss as described earlier, theclamp is placed directly on to the tooth, so thatthere is a four-point contact between the jaws ofclamp and the root. Once in position, the clampis checked for stability by pressing on the bow. Iffirm, the rubber dam may be stretched over theclamp using the wingless technique described.

It is also feasible to build up the tooth beforecommencing root canal treatment using glassionomer (for example, Vitremer). Alternatively,an orthodontic band may be cemented aroundthe tooth. On occasion, a clamp may be fitted onto a broken down tooth, but only if the gingivaltissue encroaching on to the margin is firstremoved with electrosurgery or a surgical blade.

As part of the restorative treatment, periodontalcrown lengthening, or orthodontic extrusion, maybe indicated. These procedures should be carriedout prior to commencing the root canal treatment.

BridgesBridges do not present a problem with the appli-cation of rubber dam. A suitable winged clamp isfitted onto the abutment tooth and the damstretched over the clamp. If there are any smallgaps, these can be sealed with a caulking materialsuch as Oraseal or Cavit.

When root treating teeth acting as bridgeabutments a careful check should always bemade that the bridge is not loose. If a bridge hasbecome debonded it must be removed. Thisshould be carried out before any attempt is madeto root-treat one of the abutment teeth.

Split damOccasionally, a broken down tooth may be iso-lated using a slit cut between the holes made forthe two adjacent teeth, as shown in Figure 16. Itis essential that the caulking material illustratedin Figure 9 is applied to prevent leakage andcontamination.

Finally, if an operator decides to proceed withroot canal treatment without the use of rubberdam, each hand file must be protected witheither floss tied around the handle or an appro-priate safety device. The excess saliva must becontrolled with cotton wool rolls and aspiration,and great care must be taken with medicaments.It would be advisable to inform the patient of therisks involved, and the reduced prognosis for thetreatment if salivary contamination of the rootcanal occurs.

ACCESSAccess cavity preparationThere is an old cliché that �Access is Success�.Unlike other aspects of dentistry, root canaltreatment is carried out with little visual guid-ance; therefore, the difficulties that are likely tobe encountered need to be considered. Anassessment of the following features can bemade after visual examination of the tooth, andstudy of a pre-operative periapical radiographtaken with a paralleling technique:� The external morphology of the tooth.� The architecture of the tooth�s root canal

system.� The number of canals present.� The length, direction and degree of curvature

of each canal.� Any branching or division of the main canals.� The relationship of the canal orifice(s) to the

pulp chamber and to the external surface ofthe tooth.

� The presence and location of any lateralcanals.

� The position and size of the pulp chamberand its distance from the occlusal surface.

� Any related pathology.

Before commencement of root canal treat-ment, the tooth must be prepared as follows:

Fig. 16 a) A slot has been cut in the rubber dam to enable this root to be isolated. b) However, it is essential thata caulking material is applied to prevent salivary contamination.

a b

09p527-534.qxd 27/10/2004 09:29 Page 532

PRACTICE


Fig. 18 Reducing themesial marginal ridgemay be necessary topermit clearvisualisation of thepulp chamber.

� All caries and any defective restorationsshould be removed and made good. Thetooth should be protected against fractureduring treatment.

� The tooth should be capable of isolation. � The periodontal status should be sound, or

capable of resolution.

It may be prudent to commence access cavitypreparation before isolating the tooth with rub-ber dam in order that the anatomical landmarks,tooth inclination and other helpful features arenot lost. It is, of course, crucial that the rootcanal does not become contaminated duringeither access preparation or canal instrumenta-tion, and the tooth should be isolated in anaseptic field as soon as possible.

If there is a danger of fracture of the coronaltooth structure, the cuspal height should bereduced to prevent this. If the loss of coronal tis-sue is extensive, there may be a need to provi-sionally restore the tooth with a temporarycrown, copper ring or an orthodontic band. It is,however, not always necessary to restore thetooth before carrying out endodontic proce-dures. Provided the tooth will anchor a rubberdam, the canals can be isolated from the oralcavity and a temporary seal can be placed overthe canals, this will be sufficient.

The objectives of access cavity preparation areto:� Remove the entire roof of the pulp chamber

so that the pulp chamber can be debrided.� Enable the root canals to be located and

instrumented by providing direct straightline access to the apical third of the rootcanals, as illustrated in Figure 6.17. Notethat the initial access cavity may have to bemodified during treatment to achieve this.

� Enable a temporary seal to be placed securelyin order to withstand any displacing forces.

� Conserve as much sound tooth tissue as pos-sible and as is consistent with treatmentobjectives.

The subsequent restoration of the tooth shouldalways be considered first. If the tooth is notheavily restored then only the amount of coro-nal tissue sufficient for the successful comple-tion of the root canal treatment should be

removed. However, if the tooth is already com-promised and will require some form of cuspalcoverage restoration, an onlay or a crown, thenit may be practical to reduce the cusp height,particularly mesiobuccally in molars, to enablebetter visualisation of the pulp chamber. Ifaccess to the back of the mouth is difficult, it isagain reasonable to consider reducing the mar-ginal ridge of the tooth concerned to achievethis (Fig. 18), or perhaps gain access through themesiobuccal wall. Unless the root treatment issuccessful, any further restoration to the toothwill be put at risk.

Before beginning the access cavity prepara-tion, it is wise to check the depth of the prepara-tion by aligning the bur and handpiece againstthe radiograph, in order to note the position anddepth of the roof of the pulp chamber in relationto the length of the bur in the handpiece(Fig. 19). Particular note should be made of theposition of the largest pulp horn.

The stages of access cavity preparation may besummarised as follows:1. The initial entry is made with a tungsten car-

bide or diamond bur in a turbine handpieceand the outline form completed as required.The bur is advanced towards the pulp hornsuntil the roof of the pulp chamber is justpenetrated. (Note particularly that in a molartooth the bur approaches the tooth from themesial and from the buccal. Thus the access

Fig. 17 This diagram illustrates the importanceof straight line access and correctly designedaccess cavities. If root canal treatment were tobe carried out through a Class III cavity, asshown on the left, the file would be deflectedand the canal would be transported. However, ifthe access cavity is cut incorrectly in the palatalsurface, not giving straight line access, thesame deflection and damage will occur.

09p527-534.qxd 27/10/2004 09:30 Page 533

PRACTICE


cavity is cut in the mesiobuccal segment ofthe occlusal surface.)

2. At this point, the rubber dam should beapplied if it is not already in place.

3. The removal of the entire roof of the pulpchamber, and the tapering of the walls, is nowcarried out with a safe-tipped endodonticaccess bur, as described in Part 5. (Stages 1 and3 are illustrated in the diagrams in Fig. 20.)

4. The walls of the pulp chamber may now begently flared out towards the occlusal surface.The end result should be a gentle funnel-shape, with the larger diameter at theocclusal surface. The safe tip of the bur willbe felt passively following the contours ofthe floor of the pulp chamber.

5. Any remaining pulp tissue and debris iscleared with an excavator from the floor ofthe pulp chamber and the canal orifices.

6. The access cavity should be flushed with asolution of sodium hypochlorite to removeany residual debris.

7. The canal orifices may be located with a DG16 endodontic probe. Any alteration to theaccess cavity outline form may now beundertaken to ensure a direct line ofapproach to the canal orifices. Any scleroticor secondary dentine surrounding the canalorifices may be removed with a CT4 tip in apiezo-electronic ultrasonic machine.

8. Once the canal orifices have been identified,the preparation of the coronal part of theroot canals should be commenced. Depend-ing upon the operator�s preferred technique,either Gates�Glidden burs or nickel-titaniumorifice shapers, should be employed. Copiousirrigation is necessary, together with the useof a canal lubricant containing EDTA. Thesetechniques are described in Part 7.

9. An access cavity must be seen as dynamic,with modifications being made as treatmentprogresses to permit the straightest possibleaccess of instruments.

10. It can only be repeated that access is success.If the access cavity is not large enough topermit easy and thorough shaping andcleaning of the entire root canal system, theroot canal treatment may be compromisedand the tooth lost.

1. Marshall K. Dental workspace contamination and therole of rubber dam. CPD Dentistry 2001; 2: 48-50.

2. Gergely E J. Rubber dam acceptance. BDJ 1989; 167:249-252.

Fig. 20 Thesediagrams illustratehow, in a molartooth, the burapproaches thepulp chamber fromthe mesial (a) andfrom the buccal(b). When the roofof the pulpchamber has beenpenetrated, asafe-tipped bur (c)should be used toremove the roof ofthe pulp chamberand shape thewalls withoutdamaging the floorand canal orifices.

DISTAL MESIAL

BUCCAL PALATAL

BUCCAL PALATAL

a

b

c

Fig. 19 The pre-operativeradiograph should be examinedcarefully for suitable landmarksbefore commencing the accesscavity. Here, the depth ofpenetration of the bur is beingestimated.

09p527-534.qxd 27/10/2004 09:30 Page 534


PRACTICE

Endodontics: Part 7Preparing the root canalP. Carrotte1

Research into root canal preparation has led to significant changes in instrumentation techniques. Hand files should bemanipulated by the balanced-force technique. Recent designs of endodontic instruments have variable tapers givingimproved shaping ability. Nickel-titanium rotary instruments will rapidly and safely open the main root canals creating deepspace to permit full permeation of irrigant solutions. Practitioners considering changing their endodontic technique areadvised to attend hands-on practical courses to gain competence before using these in clinical practice.

● Modern techniques for preparing the root canal involve a crown-down approach to moreefficiently remove infected debris and to improve access for irrigants.

● The balanced-force technique, with a 60° clockwise turn followed by a balanced anti-clockwisecutting motion, is accepted as the most efficient method of file manipulation, (except thatwhen using Hand GT files the motions are reversed).

● Copious irrigation with an appropriate antiseptic material is essential to clean the root canalsystem following shaping of the main canals.

● The smear layer should be removed with an EDTA solution before placing an intervisitdressing, or carrying out obturation.

I N B R I E F

Success in endodontic treatment depends almostcompletely on how well the root canal is shapedand cleaned. This part will cover the principles ofroot canal preparation, irrigation, root lengthdetermination, intracanal medication, and tem-porary fillings.

There have been more developments in recentyears in this aspect of endodontic practice thanany other. New instruments have been devel-oped, employing different metals and differentengineering philosophies. There has been a sig-nificant move away from the ISO standard 2%taper instrumentation.

Two root canal preparation techniques usinghand instruments will be described in detail, asthese are the standard techniques currentlytaught in most dental schools, and are consid-ered to be the most efficient and suitable forclinical dental practice. Details are also given ofthe use of engine-driven rotary instruments.

PRINCIPLES AND RECENT DEVELOPMENTS OFROOT CANAL PREPARATIONThe principles of root canal preparation are toremove all organic debris and microorganismsfrom the root canal system, and to shape thewalls of the root canal to facilitate that cleaningand the subsequent obturation of the entire rootcanal space. However, a tooth root rarely con-tains a single simple root canal. Accessorycanals, lateral canals, fins, anastomoses betweencanals, and an apical delta all contribute to theroot canal system, as shown in Part 1. Themajority of these anatomical features are notaccessible to instrumentation. An irrigant solution

must be used which can be flushed through thissystem, will destroy the microorganisms andpreferably dissolve organic debris at the sametime. Thus the current concept of root canalpreparation is not cleaning and shaping, butshaping and cleaning. The main root canalsshould be rapidly and efficiently shaped withinstruments to permit thorough and extendedcleaning of the entire pulpal system with theirrigant solution.

Once shaped and cleaned, the root canal sys-tem is obturated to prevent further ingress ofmicroorganisms, both apically and coronally,and to entomb any remaining microorganismsto prevent their proliferation. Currently, the rootcanal filling material of choice is gutta-percha,which requires a gradual, even, funnel-shapedpreparation with the widest part coronally andthe narrowest part at the apical constriction,normally approximately 1.0 mm short of theroot apex (Fig. 1). Wide, relatively straightcanals are simple to prepare, but fine, curvedcanals can present considerable difficulties. Inthe past, a number of techniques have beendescribed, all of which have been designed toproduce a tapered preparation.

DEVELOPMENT OF PREPARATION TECHNIQUESIn order to fully understand the current tech-niques for canal preparation, it would be benefi-cial to look briefly at previous methods, and theassociated problems which led to further develop-ment. Interestingly, in 1933 a paper was publishedin the dental literature recommending the use ofmaggots to consume and remove the necrotic

7

















10p603-613.qxd 01/11/2004 12:06 Page 603

tissue in the root canal, replacing them every 3 days. It soon became apparent that more objec-tive and controllable techniques were required!

The standardised systemThis technique was used for many years andrequired each instrument, file or reamer, to beplaced to the full working length. The canal wasenlarged until clean white dentine shavingswere seen on the apical few millimetres of theinstrument. The filing was continued for a fur-ther two or three sizes, to complete the prepara-tion. This method was satisfactory in straightcanals, but was quite unsuitable for curvedcanals. As the instrument sizes increase, theybecome less flexible and led to iatrogenic errorsin curved root canals. Common problemsencountered were ledging, zipping, elbow for-mation, perforation and loss of working lengthowing to compaction of dentine debris (Fig. 2).

The stepback techniqueThe stepback technique was devised to over-come the problem of the curved root canal andhas been described by Mullaney.1 The apicalregion is first enlarged using files to a final mas-ter apical file size 25 or 30; each successively

larger instrument is then inserted 1.0 mm lessinto the canal so that a taper is formed. Inbetween placing each larger instrument, themaster apical file is inserted to the workinglength to clear any debris collecting in the apical part of the canal; this is referred to asrecapitulation.

The stepback technique helped to overcomethe procedural errors of the standardised tech-nique in slight to moderately curved canals, butin the more severely curved root canals prob-lems still exist. There are three ways in whichsome of the problems of the curved root canalmay be overcome, by using:� A special filing technique.� A file with a modified non-cutting tip.� More flexible instruments.

Stepdown techniqueThis method, although not the term stepdown,was first suggested by Schilder in 1974, and thetechnique was described in detail by Goerig et al.2 It has been followed by other, similartechniques such as the double flared3 and thecrown-down pressureless.4 The principle ofthese techniques is that the coronal aspect of theroot canal is widened and cleaned before theapical part (Fig. 3). The obvious advantages ofthese methods over the stepback are as follows.� It permits straighter access to the apical

region of the root canal.� It eliminates dentinal interferences found in

the coronal two-thirds of the canal, allow-ing apical instrumentation to be accom-plished quickly and efficiently.

� The bulk of the pulp tissue debris and micro-organisms are removed before apical instru-mentation is commenced, which greatlyreduces the risk of extruding material throughthe apical foramen and causing periapicalinflammation. This should reduce the inci-dence of after-pain following preparation ofthe root canal.

� The enlargement of the coronal portion firsthas several benefits. It allows better penetra-tion of the irrigating solution to the entireroot canal system and forms a reservoir ofirrigant which is more readily replenished inthe canal system. It also reduces the risk ofcompacting debris apically which may blockthe canal.

The stepdown technique is now the mostwidely used technique for canal preparation,and will be described later in this part.

INSTRUMENT MANIPULATIONIn addition to the method of approach to theroot canal, there have been numerous tech-niques for the manipulation of endodonticshaping instruments.

Watchwinding and circumferential filingWatchwinding, or a continuous back and forthrotation with slight apical pressure, rapidlyadvances a fine file down a root canal. Each

PRACTICE


Fig. 1 The shape ofthe prepared rootcanal should be agradual, even taper,with the widest partcoronally and thenarrowest part1.0 mm from theroot apex.

Fig. 2 Procedural errors in the preparation of curved canals. a) Dentine debris and pulp remnantspacked into the apical part of the canal resulting in loss of working length. This may be avoided byrecapitulation with fine files and copious irrigation. b) Ledging due either to not precurving theinstrument, or forcing it into the canal. c) Apical zip caused by rotating the file excessively. d) Perforation due either to persistent filing with too large an instrument, or continual zipping. Notethe narrower part of the canal in c) and d) is termed an elbow. This makes obturation of the rootcanal very difficult in the widened apical area. e) Strip perforation caused by overpreparing andstraightening the curved canal.

(a) (b) (c) (d) (e)

10p603-613.qxd 26/10/2004 14:55 Page 604

slight turn engages the flutes of the file in thecanal wall and removes dentine. Only fine filesshould be advanced to the apex in this way asthere is a danger of compacting pulpal debrisahead of the file. If such a blockage occurs it canbe extremely difficult to remove.

Once the file has reached the desired length, apush-pull filing action was used, moving the filecircumferentially around the canal walls. Whenusing K-type files an attempt was made to file onthe outstroke only, again to reduce the apicalcompaction of debris. Hedstroem files were moreefficient for circumferential filing, althoughthese should not be used when watchwinding.Research into canal preparation found twodistinct problems with circumferential filing.

The first was a tendency to preferentially filethe inside wall of a curved canal. The techniqueof anticurvature filing was put forward byAbou-Rass et al.5 Anticurvature filing involvesfiling predominantly away from the inner curveof a root to reduce the risk of a strip perforation.The mesiobuccal roots of maxillary molars andthe mesial roots of mandibular molars are theteeth most frequently at risk. The method is usedonly in canals with a moderate-to-severe curve.

The second finding was that once the fileengaged in the coronal part of the root canal, theapical flutes tended not to cut dentine butremain passive. The majority of the filingoccurred coronally, which tended to leaveunderprepared canals which were not fullycleaned.

The balanced force techniqueThe balanced force technique, first described byRoane et al.,6 is now the most widely taughttechnique for manipulating handfiles. It is par-ticularly good when negotiating the curved rootcanal. The technique requires flexible files withnon-cutting tips. The file is inserted into thecanal until slight resistance is felt and thenrotated 60° clockwise to engage the flutes intothe dentine. If a greater movement is made,iatrogenic problems can quickly arise. Usinglight apical finger pressure to hold the file atexactly the same depth in the canal, the file is

now rotated through 360° in an anticlockwisedirection. The first 60° of this turn cuts off thedentine engaged in the flutes of the file, and theremainder of the movement picks up this den-tine in the flutes of the file prior to the nextcycle. The amount of apical pressure required torotate the file anticlockwise is just sufficient toprevent it from winding out of the canal. Watch-ing the rubber stop in relation to the tooth assistsin keeping the file steady with no in or outmovement.

If the file is engaged too far into dentine withthe first clockwise movement, ie if the turn isgreater than 60°, excessive force is applied to thefile during the cutting phase, and the file mayfracture. The balanced force cycle of movementshould be made no more than three times beforethe file is withdrawn to be cleaned, ideally bypressing it into a sterile sponge. The root canalsystem should be irrigated copiously before thefile is reintroduced. Using this method, curvedcanals may be prepared to the full workinglength without producing apical transportation.

Ultrasonic techniqueUltrasound has been used to activate speciallydesigned endodontic files. Ultrasound consistsof acoustic waves which have a frequency high-er than can be perceived by a human ear. Theacoustic energy is transmitted to the root canalinstrument, which oscillates at 20�40,000 cyclesper second, depending on which unit is used.The superior cleaning effect is achieved byacoustic streaming of the irrigant and not, asoriginally thought, by cavitation.7 Irrigationwith sodium hypochlorite is necessary,8 althoughsome of the ultrasonic units are not designed toaccept sodium hypochlorite through the systemand, if water is used, they will be less efficient intheir cleansing effect. Even when units designedto take sodium hypochlorite are used, dailymaintenance must be carried out to preventdamage, particularly to metals, because theirrigant is corrosive.

The irrigant passes down the shank of theinstrument and into the root canal, producing acontinuous and most efficient system. Acoustic

PRACTICE


Fig. 3 The root canal in this toothcontains necrotic infected debris.The objective in endodontics is toremove the debris withoutextruding any through the apicalforamen. It makes good sense touse a technique which cleans thecoronal part first and then theapical portion.

10p603-613.qxd 26/10/2004 14:55 Page 605

streaming is produced by the rapid file oscilla-tions in the irrigant within the root canal. Withmore recent developments, ultrasonic machinesare now largely used for their efficient irrigationproperties rather than for canal shaping.

Automated devicesThere have been many automated handpieces onthe market over the years which claim to makethe preparation of root canals quicker and moreefficient. Although different designs andmechanical actions have been tried, they haveall suffered from the inherent difficultiesreferred to earlier, caused by rotating or twistingconventional stainless steel instruments, such aszipping, perforation, canal transportation andbroken instruments.

Nickel-titaniumHowever, the development of nickel-titaniumalloys has revolutionised automated root canalpreparation. The remarkable ability of thesealloys to alter their crystalline state gives instru-ments manufactured from nickel-titanium pro-found flexibility. Mechanised instruments canwithstand the distortions caused by repeatedrotation in curved canals without causingpreparation errors. Most of these instrumentshave design features such as radial lands (Fig. 4)to keep the instrument centred in the canal, anda non-cutting tip to guide the instrument downthe canal. New designs are constantly appearing,(Fig. 5) and the clinician should ensure that con-siderable experience with whichever system ischosen has been obtained on extracted teeth,before the instruments are introduced into clinicalpatient treatment.

A controlled high-torque, low-speed motor isrequired for efficient use of the instruments.Most manufacturers of endodontic instrumentsproduce such a motor, and their complexity mayvary from that illustrated in Part 5, Figure 12, tothat shown here in Figure 6. It must be empha-sized that these nickel-titanium instruments dohave a limited life, and will fracture in time aftera large number of rotations. Slow (150�250 rpm)rotation does not impede their efficiency butextends their life. However, it is recommendedthat the instruments should be discarded after acertain number of cases as described by the

manufacturer, and more frequently if an instru-ment has been used to negotiate difficult curvedcanals. The files should also be removed fromthe canal and cleaned frequently. Althoughdebris is moved coronally it tends to compact inthe file flutes, and if these become occluded theinstrument will fracture. The separated part willengage in the root canal and may proveextremely difficult to remove.

IRRIGATIONSodium hypochloriteThe importance of effective irrigation in rootcanal preparation cannot be overemphasised. Amaxim in endodontics states that it is what youtake out of a root canal that is important, notwhat you put in. Sodium hypochlorite is consid-ered the most effective irrigant, as it is bacterici-dal, dissolves organic debris and is only a mildirritant. It must be clearly understood that almostany irrigant solution will cause an inflammatoryreaction in the periapical tissues if it is expressedunder pressure.9 Great care must be taken tofollow the irrigation regime described below.

There is considerable debate about the recom-mended or optimum concentration of sodium

PRACTICE


Fig. 4 A diagram of a nickel-titanium rotary file showingthe concept of radial lands.

Fig. 5 One modern system of nickel-titanium rotaryinstruments � the System GT.

Fig. 6 A �state-of-the-art� endodontic motor, being arechargeable slow-speed, high-torque handpieceencompassing an apex locator and associated facilities.

10p603-613.qxd 26/10/2004 14:56 Page 606

Fig. 7 EDTA solution for finalflushing of the canal system.

PRACTICE


hypochlorite. Ordinary domestic bleach, such asthat purchased from any supermarket, hasapproximately 5% available chlorine. This maybe used neat, or may be diluted with purifiedwater BP up to 5 times. Greater dilutions do notaffect the antibacterial properties, but diminishthe tissue dissolution property. Diluted solutionsmust therefore remain in the root canal forlonger. Warming the irrigant makes it even moreeffective.10 There are other commercially avail-able sodium hypochlorite products, but it mustbe emphasised that there should be no otheradditives, particularly sodium chloride.

During preparation, the root canal should bekept wet, with copious irrigation used aftereach instrument. The irrigant in the canal isonly replaced to the depth of insertion of theneedle. The needle must remain loose in thecanal while the irrigant is being injected, toprevent the solution being expelled under pres-sure into the periapical tissues. To obtain totalreplacement of irrigant solution in the rootcanal, the smallest needle available (30-gauge)should be placed at the apical foramen. Obvi-ously, this is a most hazardous procedure and itis suggested that the irrigation needle is onlyinserted to a maximum depth of 2.0 mm shortof the working length. A file may then beworked in the apical 2.0 mm, to stir and with-draw the dentine debris further into the canal,so that it can be flushed away. There are severaldifferently designed irrigation needle tips, butin the author�s opinion these are of little impor-tance compared with the diameter of the nee-dle. Whatever the tip design, unless the needlecan penetrate loosely to the correct depth in theroot canal, irrigation, however copious, willnot remove dentinal debris.

ChlorhexidineAs referred to in Part 5, some practitioners haveconcerns about the use of sodium hypochloriteand prefer to use a solution of chlorhexidine.Whilst this has a similar antibacterial spectrum,it does not have the ability to dissolve organicdebris and may not clean the entire root canalsystem as effectively. However, chlorhexidinedoes exhibit substantivity (adherence to den-tine) and there is some evidence to suggest thatit may be a more appropriate irrigant forretreatment of failed orthograde cases wheresodium hypochlorite was the original irrigant.

Ethylene-diamene tetracetic acid (EDTA)solutionEndodontic instrumentation creates a smearlayer on the root canal walls, particularly whenusing nickel-titanium rotary instruments. Thissmear layer occludes the dentinal tubules, andmay protect microorganisms from the effects ofthe sodium hypochlorite irrigation. Flushing thecanal with EDTA solution (Fig. 7) periodicallyduring instrumentation removes the smear layer,and enables more effective cleansing. The finalirrigation should always be with sodiumhypochlorite.

LUBRICATIONProprietory pastes containing EDTA are avail-able, in combination with various agents, whichgreatly help instrumentation by chelating andsoftening the dentine. If a small portion is dis-pensed near to the file storage system, a littlemay be picked up on the tip of each new file as itis selected (Fig. 8).

DETERMINATION OF ROOT CANAL LENGTHThe exact apical termination of the root canalpreparation has always been a subject of con-tention. The pedantic answer is that the rootcanal should be prepared to that point where the�inside� of the tooth becomes the �outside�. Someauthors suggest this is the apical constriction,some the cemento-dentinal junction, some sug-gest that the apical foramen should be enlarged,some suggest that the preparation be taken to anarbitrary point 1 mm from the radiographicapex. As described in Part 4, the apical anatomymay be complex, and the term apical delta maybe more appropriate. This author considers thatthe preparation should be taken as close as pos-sible to the cemento-dentinal junction, and thatwherever possible the foramen of the majorcanal should be kept patent. (This technique isdescribed later.) The other minor canals formingthe apical delta will only be cleaned by antibac-terial irrigation flushing through the entire canalsystem.

An estimate of the root length is made fromthe pre-operative radiograph taken with a paral-lel technique. However, confirmation of theactual working length is not carried out until thecoronal preparation of the canal has been com-pleted, as this may straighten a curved canalwhich would change a measurement that hadbeen taken too early. Most operators now con-firm the actual working length when the crown-down preparation has progressed to within 3 or4 mm of the estimated working length. There arethree accepted methods for this determination.

Working length radiographA file is placed carefully in the canal until it iswithin approximately 2.0 mm of the overalllength. Before insertion the file should be pre-curved to the shape of the canal and gentlymanoeuvred into position, if necessary using awatchwinding technique and slight apical pres-sure. For accurate reading of the radiograph asize 15 file is usually necessary. A silicone stop

Fig. 8 EDTA paste should be placednear the files and picked up on eachinstrument before use.

10p603-613.qxd 26/10/2004 14:57 Page 607

`

PRACTICE


on the instrument shank is positioned against areference point on the tooth, and both the lengthand the reference point should be noted in therecords. When taking diagnostic radiographs,use should be made of the �buccal object rule�,where there are two or more canals present inthe root (Figs 9 and 10). A second way of achiev-ing the same result is to place a Hedstroem file inone canal and a K-file in the other, as the differ-ence between the two is clear on the radiograph.The working length is calculated by measuringdirectly on the radiograph from the tip of theinstrument to 1.0 mm short of the radiographicapex. It is only possible to estimate this arbitraryposition using this technique.

Electronic apex locators Electronic apex locators (seen in Part 5, Fig. 15)may be used as an alternative to a working-length radiograph, assuming that a pre-opera-tive film has been examined to obtain an esti-mated figure. These machines are capable ofaccurate measurement, and will give the loca-tion of the apical foramen. Apex locators areessential when a patient elects to have a mini-mum number of further radiographs taken.Many practitioners now use them routinely, par-ticularly when the outline of the canal on thepre-operative film is indistinct or the canalcurves towards or away from the radiographbeam. Modern apex locators work using differ-ent frequencies, determining the ratio betweenthe different electric potentials proportional toeach impedance. There is no longer any need to

dry the canal before use as they work in the pres-ence of electrolytes. There is a distinct learningcurve with their use, but it is usually apparentwhether or not the measurement is in accor-dance with the original radiographic estimatedworking length. Errors may occur if there is alarge coronal restoration or metallic crowncausing a short circuit; if there is an open apexwith a large periradicular lesion, or if there is aperforation. These are usually apparent and further measures should be taken.

In use, a file is inserted into the root canal andan electrical contact is made with the shank of theinstrument. The device has a second electrode,which is placed in contact with the patient�s oralmucosa. A digital display or audible signal showswhen the tip of the instrument reaches the apicalforamen. There is no doubt that modern apexlocators can be even more accurate in lengthdetermination than a radiograph.11,12

Tactile sensationAn experienced clinician, armed with an accu-rate pre-operative parallel radiograph, can oftenfeel the apical constriction with a fine instru-ment. If tactile sensation is in accord with theestimated length, further confirmation may notbe necessary.

PREPARATION OF THE ROOT CANALTwo techniques will be presented in detail, oneusing conventional hand instrumentation andone using nickel-titanium hand Files of GreaterTaper. The stepdown technique has been modi-fied slightly from the original description byGoerig.2 The use of nickel-titanium rotaryinstruments is presented in general terms only.As discussed earlier, there is a rapid developmentof these instruments, and the instructions andguidance of the manufacturers of the specificinstruments chosen by the clinician shouldalways be adhered to. It is strongly recommend-ed that appropriate hands-on training is under-taken, practising the technique on a large num-ber of extracted teeth before taking the newprocedures to a patient.

STEPDOWN TECHNIQUE WITHCONVENTIONAL 2% TAPER INSTRUMENTSA pre-operative radiograph is taken, rubber damplaced and an access cavity prepared. The canal

Fig. 10 The diagnosticradiograph was takenfrom the mesial withthe x-ray conepointing distally. Thebuccal canal istherefore the distalone on the radiograph.

Fig. 9 Thebuccal objectrule. When thex-ray cone ismoved to themesial anddirecteddistally, thebuccal canalwill appear themost distal onthe radiograph.

10p603-613.qxd 26/10/2004 14:59 Page 608

Fig. 12 A diagrammatic illustrationof the sequence of instruments in aconventional 2% taper hand filecanal preparation.

PRACTICE


preparation is divided into two parts: i) coronalpreparation, which permits radicular access forii) apical instrumentation.

Coronal preparation or radicular accessFirst, the pulp chamber is copiously irrigated withsodium hypochlorite. Gates�Glidden burs arenext introduced into the canal, directed apicallyand laterally away from the furcation. The largersizes are introduced first, working sequentiallyfurther down the canal with smaller sizes. Somecanals will accept a size 6 bur, but normally a size4 would be used first, followed by a size 3. Eachbur will penetrate 2�3 mm further than the pre-vious one. EDTA paste should be used with eachbur, and the canal should be irrigated betweeneach entry. Eventually, in a relatively straightcanal, the No. 2 bur is inserted 10�12 mm intothe canal from the occlusal reference point. In acurved canal the pre-operative radiographshould be checked for the maximum straight linepenetration of the bur.

Gates�Glidden burs should be rotated withconstant medium drill speed from the time theyenter the canal until removed. Gates-Gliddenburs must not be taken into a curve, or they willalmost certainly fracture. If the shank of a burdoes break, it usually does so near the handpiecehead and may be retrieved easily from the tooth,as seen in Figure 11. However, if the head doesbecome separated from the shank within thecanal, removal may be extremely difficult.13

The bur may be flexed against the canal wallslightly on withdrawal to ensure that the naturalshape of the canal is maintained. Thus a roundcanal will remain round, but an oval canal willbe prepared to a smooth oval funnel. A wide ovalor �figure-of-eight� shape may need preparing atboth extremities to produce a wide flare. Instru-mentation with the stepdown technique in theradicular access is accomplished using only lightpressure directed apically and away from thefurcation, or perforation may result.

An alternative to Gates�Glidden burs is theuse of standard flexible K-type files with safetips, used with the balanced force technique. Fol-lowing initial widening of the mouth of thecanal only with a Gates�Glidden bur, the largesthand file which will enter the canal is selectedand worked apically, using EDTA paste as alubricant. Once penetration proves difficult thefile should not be forced further, or fracture mayresult. The next size smaller file is selected, andsequentially smaller files used until the coronalpreparation is complete.

Apical preparationThe coronal flaring already carried out makesaccess to the apical portion of the root easier, asthere are no dentinal obstructions and access ismore direct. Thus, once the coronal preparationis complete, flexible K-type files with safe tipsmay be used sequentially with the balancedforce technique previously described. A sizeappropriate to the particular canal and the finalsize Gates�Glidden drill is selected, perhaps a

size 60, the tip dipped into a canal lubricant, andthe instrument worked slightly further into thecanal. Sequentially smaller files are selecteduntil the canal is prepared to 3�4 mm short ofthe estimated working length. Now the actualworking length must be confirmed by one of themethods described earlier, radiograph or apexlocator. Once the working length has been con-firmed, the apical preparation can be completed.In narrow or sclerosed canals the operator mayprefer to take a small 08, 10 and 15 files to work-ing length before commencing any canal prepa-ration. The prepared canal then acts as guidancefor the larger sizes. This procedure is illustrateddiagrammatically in Figure 12.

Stepback techniqueFollowing the preparation of the coronal part ofthe root canal, the apical preparation may alsobe carried out using the stepback technique.Starting with the size 15 file at the working

Fig. 11 A Gates-Glidden bur whichfractured during use in the rootcanal, showing the normal point ofseparation, permitting removal withSteiglitz forceps. However, b) showsthat this is not always the case.

a

b

1 Gates-Glidden #4irrigate



4 K-flex type file #60irrigate



7 K-flex type file #40irrigateWhen 3mm from estimatedworking length verify actualworking length with x-ray orapex locator.


9 K-flex type file #30irrigate with EDTAirrigate & dry

10p603-613.qxd 26/10/2004 14:59 Page 609

PRACTICE


length, and progressing to sizes 20 and 25, anapical stop is made. Copious irrigation and reca-pitulation with fine files will prevent build-up ofcanal debris. The master apical file will usuallybe no greater than 25 or 30. The apical portion ofthe canal is now tapered by stepping back. A fileone size larger than the master apical file isworked with balanced force to 1.0 mm short ofthe working length. Each successively larger file

size is inserted 1.0 mm less than the previoussize until the radicular access preparation isreached. In between each larger file selection themaster apical file is inserted to full workinglength (recapitulation) and irrigation is used toremove all the debris.

STEPDOWN TECHNIQUE WITH HAND FILES OFGREATER TAPERThe stepdown technique may be modified withthe use of this range of files described byBuchanan in 1996.14 The balanced force tech-nique is used as described previously, except thatthese instruments are used in the opposite rota-tion to conventional files. It was considered thatthe crucial part of the balanced force technique isthe cutting cycle. Right-handed clinicians (repre-senting some 90% of the work-force) can makethis movement more easily in a clockwise direc-tion than anticlockwise. Thus the initial move-ment to engage the dentine with these files onlyis a 60° turn anticlockwise, and the balancedforce cutting motion is 360° clockwise.

Following access to and irrigation of the pulpchamber the canal must first be gently exploredto length with conventional 2% taper hand files.A gentle watchwinding technique is used withsize 08, 10 and 15 files. The tip of the GreaterTaper File then acts as a pathfinder rather thanas a preparation file.

Using EDTA lubrication paste, the largest filewith a blue handle and a taper of 12%, is usedfirst to gain coronal access. When resistance is met the instrument is not forced furtherapically, but the red handled 10% taper file isused to penetrate further. The yellow handled8% taper and white handled 6% taper follow in sequence, until the canal is prepared toworking length.

The technique is varied according to the clini-cal situation. In a wide, straight canal, only a sin-gle 12% taper file may be required. In a narrow,curved canal, the clinician may only use thesmaller files, alternating them repeatedly to create space for further apical penetration. Beforeattempting to instrument narrow, curved canalsit is again always advisable to use conventional2% taper instruments from size 08 through tosize 20. The tip of the Greater Taper file then actsas a pathfinder, dentine removal occurring at theside of the instrument, not the tip.

Once a smooth-tapered canal has been pre-pared, the clinician may consider it necessary insome cases to enlarge the apical constrictionslightly with conventional hand files.

The technique is summarised in Table 1, andshown in Figure 13.

NICKEL-TITANIUM ROTARY TECHNIQUEThe development and design of these instru-ments has been referred to earlier, and should bereferred to in conjunction with this descriptionof technique. Each manufacturer of these instru-ments produces a protocol for use for their ownspecific product. As it would not be appropriateto describe any single manufacturer�s technique

Fig. 13 An illustration of the stepsinvolved in the preparation of asimulated root canal with Hand Filesof Greater Taper.

`

Table 1 Root canal preparation using GT hand files

Aceess and coronal preparation� Access � Remove roof of pulp chamber and locate canal orifices with the use of safe ended access

Bur and DG16. Ensure straight line access to the canal orifice.

� Irrigate pulp chamber with sodium hypochlorite

� Estimate working length from pre-operative radiograph.

� Using a gentle watchwinding technique, and EDTA chelating agent/lubricant (File Eze/Glyde),advance a #08, #10, #15 and #20 K-type file to about 3 mm short of the estimated working length.

� If desired, with irrigation with NaOCI and with the use of the lubricant, open up the canal orificeusing Orifice Shaper 4 & 3 crown down for approximately 3 or 4 mm. Orifice Shapers should berotated at 250 rpm and used with a light pecking motion, keeping the instrument rotating withinthe canal at all times (Gates-Glidden drills can also be used for this procedure).

Mid-canal preparation� Continue irrigation with NaOCI and the use of lubricant. Insert the #12 (BLUE) GT hand file within

the canal and using a reverse balanced force action (60° turn anticlockwise followed by clockwise180° turn with apical pressure � the �balanced force�) progress the file until resistance is felt and nofurther advancement of the file is possible. Do not use excessive force, and remove and clean thefile after every three cycles.

� In the same manner insert the #10 (RED) GT hand file, repeating the procedure to penetrate furtherdown the canal

� Either repeat the process with the #08 (YELLOW) hand file, or if approximately 3 mm from theestimated working length, proceed to:

Apical preparation� Establish working length using electronic apex locator or with a diagnostic radiograph.

� Negotiate canal to full working length advancing #15 and #20 K-type files with watchwinding orbalanced force motion.

Apical shaping� Check canal patency using #15 K-type file with copious irrigation of NaOCI and use the #08

(YELLOW) GT hand file looking for resistance.

� Check canal patency before introducing the #06 (WHITE) GT hand file, this file should progress tofull working length.

� Apical gauging can be checked or further enlarged with the use of K-type files.

� Continue irrigation with NaOCI for a total preparation time of 30 minutes, followed by final rinse ofEDTA solution.

The above procedural protocol may have to be adapted taking into account the apical constriction,working length, apical curvature and general canal anatomy.

10p603-613.qxd 26/10/2004 15:00 Page 610

PRACTICE


here, the description which follows must there-fore be generic. The basic concepts are the samewhatever the instrument chosen. The techniquefor use is crown-down, with copious irrigation.Indeed, these instruments conform totally to thestated objectives in modern root canal therapy,shaping the canal rapidly and efficiently so thatthorough cleaning of the root canal system canbe carried out with appropriate irrigants. Thefiles must be used in a slow-speed, controlledtorque motor, or they are prone to fracture.

Coronal preparation or radicular accessNickel-titanium instruments cannot easily beprecurved, and require straight line access to theroot canal orifice. The use of ultrasonic tips torefine the access cavity has already beendescribed. Nickel-titanium �orifice shapers� havereplaced Gates-Glidden drills, and may be usedsequentially from the largest to the smallestsizes. These remain centred in the canal and willflare the canal walls to approximately halfwaydown the canal. Their use may be restricted innarrow or curved canals. They are used with avery light apical pressure, often described as the�pencil-lead� pressure, ie that which would breakthe lead when using a propelling pencil. Eachinstrument should be used for no more than5�10 seconds at a time before removing from thecanal, cleaning, irrigating and adding lubricant.

Apical preparationOnce the coronal preparation is completed, thecanal should be explored to full working lengthusing fine hand files and the balanced force tech-nique. The working length should be confirmed,and the canal enlarged to a size 15 or 20. If this isnot done, the rotary instrument will have to cutat its tip, rather than along its length, which maylead to jamming and fracture. Each time a file isremoved from a canal after use the position ofthe dentine debris in the flutes should be inspect-ed. The instruments should cut along their entirelength. If debris is only seen at the tip, the instru-ment may be excessively stressed, which maylead to fracture. The apical part of the canal maynow be prepared with sequentially smallerinstruments, stepping down the canal with eachsmaller size. It may be necessary to return to alarger size during preparation (recapitulation) tocreate more space for the smaller instruments.

Summary of technique � Motor set at slow speed recommended for

instrument, usually 150�250 rpm.� Use each instrument for only 5�10 seconds.� Light apical pressure, using either a gentle

�planing� pressure, or a slight �pecking�motion depending upon the instrumentdesign.

� Use EDTA lubricant with each instrument.� Copious irrigation with sodium hypochlorite

between instruments.� Step down in sequence from the largest to the

smallest. (NB This will depend upon whichsystem is being used. If variable taper files

have been selected, as in Fig. 5, then a 10%taper file will be used until resistance is felt,moving to an 8%, 6% and 4% until any ofthese reaches working length, depending uponthe canal size. Alternatively, if a single taper,variable tip system has been selected, thelargest tip size will be used first, reducing sizesas the canal is negotiated until, once again,one instrument reaches working length.)

FURTHER READINGIt must be stressed that the techniques describedare generic, and that hands-on practice is essen-tial, following the specific manufacturer�s proto-col until competence is achieved. The variousinstruments and techniques are described, com-pared and contrasted, in numerous publications,for example.15�18 The prudent clinician wouldbe advised to refer to the endodontic literaturebefore embarking on new purchases and clinicalpractice. A useful series of clinical articles waspresented by Buchanan.19

PATENCY FILINGResearch has shown that most canal preparationtechniques lead to the extrusion of debristhrough the apical foramen. This is removed bythe normal body defence systems, although acertain amount of inflammation will result.Concern has been expressed by some authoritiesthat such debris may remain in the apical con-striction, and may contribute to failure, particu-larly if it harbours microorganisms.20 The tech-nique of patency filing involves passivelyinserting a small file, size 08 or 10, 2 mm beyondthe established working length. No attempt ismade to instrument the foramen, merely to keepit open or patent by deliberately extruding thedebris into the periradicular tissues.

The literature on patency filing is at presentquite equivocal. No research workers have beenable to show either a decrease or an increase inpost-operative symptoms or case prognosis. Thetechnique remains subjective and subject to theoperator�s personal philosophy.

INTRACANAL MEDICATIONCalcium hydroxideThere is almost universal agreement that whenan intervisit dressing is required, calciumhydroxide is the material of choice, and this isdiscussed in Part 9. There is far less agreement asto whether such dressings are indicated. Single-visit endodontics � the shaping, cleaning andobturation of the root canals in one appointment� remains controversial. Most endodontistswould agree that when the tooth under treat-ment is not infected, for example when perform-ing elective endodontics or treating large expo-sures of vital pulps, completing treatment in asingle visit is advisable. However, Sjögren et al.showed a significant increase in prognosis wheninfected root canals were dressed with calciumhydroxide for one week before obturation.21

Gutmann has suggested that this effect was onlyapparent because their research employed 1%

10p603-613.qxd 26/10/2004 15:01 Page 611

PRACTICE


sodium hypochlorite, whereas the use of a fullstrength solution would preclude the need forsuch a dressing.22 The wise practitioner wouldconsider which approach best suits his or herstyle of practice.

Calcium hydroxide is applied with a spiralpaste filler (noting the caution given at Part 5,Fig. 20), or a fine-tipped syringe may be used asseen in Figure 14. Care should always be takennot to extrude the material beyond the apicalconstriction. If this happens, inflammation mayresult which could take several days to subside.Calcium hydroxide containing points are avail-able from which it is postulated that ions will dis-sociate into the fluid in the root canal, and whichmay be better controlled in apical length. How-ever, research supporting this has not yet beenreported in the endodontic literature.

A recent addition to the range of intracanaldressing available is the mixture Vitapex, shownat Figure 15. As well as calcium hydroxide, thematerial contains iodoform. It may be indicatedfor deep-seated infections of the root canal, suchas the upper canine, shown in Part 2, Figure 1,which had resulted in an extra-oral sinusbeneath the patient�s eye. This closed and thetooth healed following one week�s dressing.Extreme care is needed to ensure that this vis-cous dressing has been fully removed from thecanal walls before obturation.

SteroidsSteroids are readily obtainable in the form of tri-amcinalone (Ledermix paste). The use of thepaste for dressing an inflamed vital pulp prior tocommencing root canal therapy is discussed inPart 3. Some authorities recommend the use ofthe paste as an intervisit medicament pastewhen severe periradicular inflammation is pres-ent. It is suggested that it may be wiped on thecanal wall using a file or paper point which isthen withdrawn; a small amount is then placed

on a pledget of cotton wool and sealed into thepulp chamber between appointments. Theauthor prefers to mix the paste with a calciumhydroxide preparation, adding a little sterilewater or local anaesthetic to make the mixtureslightly more fluid. The canals may then be com-pletely filled with this mixture prior to placing atemporary coronal seal.

Of course, no intracanal medicament yetexists that will sterilise the root canal, and theimportance of biomechanical preparation cannotbe stressed too strongly.

TEMPORARY RESTORATIVE MATERIALSIf endodontic treatment cannot be completed inone visit, it is essential that a temporary restora-tive material is used as an inter-appointmentdressing that will not permit access to bacteriaor oral fluids. Even when the root canal treat-ment has been completed, a well-sealed tempo-rary restoration is necessary prior to the place-ment of a permanent restoration. The materialshould prevent contamination of the root canalsystem and must be sufficiently strong to with-stand the forces of mastication.

Two different temporary materials are recom-mended. Of the many proprietary materials,Cavit has been shown to provide the best seal.23

Cavit provides a good seal, is simple to applyand quick to set. On the other hand, it lacksstrength and will not stand up to masticatoryforces. It should be confined to single surfacefillings for periods not exceeding a week. How-ever, the shape of an endodontic access cavity isnot retentive, and all such materials will eitherleak or be lost entirely in time. Any ingress ofmicroorganisms may reinfect a prepared canal,and the time saved by using a rapid techniquemay be severely lost if such leakage occurs. Thusthe use of a glass-ionomer cement should beconsidered. It is adhesive, antibacterial, standsup well to forces of mastication and is morestable than other materials.

It is a useful routine, with an inter-appoint-ment dressing, to place a sterile pledget of cot-ton wool in the pulp chamber, followed by alayer of gutta-percha. The temporary restora-tive material is then placed over the gutta-percha (Fig. 16). At the next visit, a high-speedbur may be used to remove the temporaryrestoration without any danger of filling mate-rial lodging in the canal entrances or blockingthe canals. The gutta-percha provides a base forthe restorative material and prevents the burbecoming caught in the cotton wool when thetemporary filling is removed.

Fig. 15 Vitapexintracanal dressing.

Fig. 14 A fine tipped plastic canulamay be used to deliver medicamentsdeep into the root canal. Its size maybe compared to the standard 28-gauge irrigating needle.

10p603-613.qxd 26/10/2004 15:01 Page 612

PRACTICE


Fig. 16 A layer of gutta-percha temporary fillingmaterial has been placed to protect the root canalsbefore the restorative material is applied. The insetshows how this may be removed and prevents fragmentsof the temporary filling entering the root canal.

British Dental Journal November 1904Miscellanea

A Caution

A correspondent at Kettering warns those of his vicinity against an obvious begging impos-tor who called upon him personating a practitioner at Wrexham. We learn from the letterthat he has been inconvenienced by enquiries from others who have been victimised and iswilling to prosecute if the man can be detained.

Br Dent J 1904


1. Mullaney T P. Instrumentation of finely curved canals.Dent Clin North Am 1979; 23: 575�592.

2. Goerig A C, Michelich R J, Schult H H. Instrumentationof root canals in molars using the stepdown technique.J Endod 1982; 8: 550�554.

3. Fava L R. The double flared technique: an alternativefor biomechanical preparation. J Endod 1983; 9: 76�80.

4. Morgan L F, Montgomery S. An evaluation of thecrown-down pressureless technique. J Endod 1984; 10: 491�498.

5. Abou-Rass M, Frank A, Glick D. The anticurvaturefiling method to prepare the curved root canal. J AmDent Assoc 1980; 101: 792�794.

6. Roane J B, Sabala C L, Duncanson M G. The �balancedforce� concept for instrumentation of curved canals.J Endod 1985; 11: 203�211.

7. Ahmad M, Pitt Ford T, Crum L. Ultrasonic debridementof root canals: an insight into the mechanismsinvolved. J Endod 1987; 13: 93�101.

8. Griffiths B, Stock C. The efficiency of irrigants inremoving root canal debris when used with anultrasonic preparation technique. Int Endod J 1986;19: 277�284.

9. Sabala C L, Powell S E. Sodium hypochlorite injectioninto periapical tissues. J Endod 1989; 15: 490�492

10. Berutti E, Marini R, A scanning electron microscopeevaluation of the debridement capability of sodiumhypochlorite at different temperatures. J Endod 1996;22: 467�470.

11. Pagavino G, Pace R, Baccetti T. A SEM study of in vivoaccuracy of the Root ZX electronic apex locator.J Endod 1998; 24: 438�441.

12. McDonald N J. The electronic determination ofworking length. Dent Clin North Am 1992; 36:293�307.

13. Lumley P J. Management of silver points and fractured

instruments. CPD Dentistry 2000; 1: 87�92.14. Buchanan L S. The art of endodontics: Files of greater

taper. Dentistry Today 1996; 42: 44�49.15. Kavanagh D, Lumley P J. An in vitro evaluation of

canal preparation using Profile .04 and .06 taperinstruments. Endod Dent Traumatol 1998; 14: 16�20.

16. Hulsmann M, Schade M, Schafers F. A comparativestudy of root canal preparation with HERO 642 andQuantec SC rotary Ni-Ti instruments. Int Endod J2001; 34: 538�546.

17. Barbakow F, Lutz F. The Lightspeed preparation techniqueevaluated by Swiss clinicians after attending continuingeducation courses. Int Endod J 1997; 30: 46�50.

18. Bryant S T, Thompson S A, Al-Omari M A, Dummer P M H. Shaping ability of Profile rotarynickel-titanium instruments with ISO sized tips insimulated root canals. Int Endod J 1998; 31: (part 1)275�281, (part 2) 282�289.

19. Buchanan L S. The standardised taper root canalpreparation. Parts 1�6. Int Endod J. Part 1 2000; 33:516�529; Part 2 2001; 34: 63�71; Part 3 2001; 34:149�156; Part 4 2001; 34: 157�164; Part 5 2001; 34:244�249; Part 6 2001; 34: 250�259;

20. Ruddle C J. in Cohen S and Burns R C, Pathways of thePulp Eighth Edition, Page 276�277. St Louis: Mosby,2002.

21. Sjögren U, Figdor D, Persson S, Sundqvist G. Influenceof infection at the time of root filling on the outcomeor endodontic treatment of teeth with apicalperiodontitis. Int Endod J 1997; 30: 297�306.

22. Guttman J L. Presentation to The British EndodonticSociety Spring Scientific Meeting, October 2000,Chester, UK.

23. Anderson R W, Powell B J, Pashley D H. Microleakageof three temporary endodontic restorations. J Endod1988; 14: 497�501.

10p603-613.qxd 01/11/2004 12:07 Page 613

kishore

Rectangle

BRITISH DENTAL JOURNAL VOLUME 197 NO. 11 DECEMBER 11 2004 667

PRACTICE

Endodontics: Part 8Filling the root canal systemP. Carrotte1

The purpose of the obturation phase of a root filling is two-fold; to prevent microorganisms from re-entering the root canalsystem, and to isolate any microorganisms that may remain within the tooth from nutrients in tissue fluids. The seal at the apicalend of the root canal is achieved by a well-fitting gutta-percha master point, and accessory points, although heated techniquesmay result in a better seal. The seal at the coronal end is achieved by the application of a layer of resin-modified glass ionomercement as accessory canals may lead from the floor of the pulp chamber to the furcation area. It must always be rememberedthat success will only be achieved if the root canal system has been as thoroughly debrided as possible of infected material.



● No matter how well the obturation of the root canals is performed, success will be dependantupon the initial cleaning and debridement of the entire root canal system.

● Cold lateral compaction of a master gutta percha point and accessory points remains thenorm against which other obturation methods are assessed.

● The gold standard of obturation is the warm vertical compaction of gutta percha with aheated plugger.

● Research suggests that the coronal seal, achieved with a layer of glass ionomer cement onthe floor of the pulp chamber, may be more important than the apical seal.

I N B R I E F

In modern endodontic treatment the emphasis isplaced far more on cleaning and preparing theroot canal system than on filling it. This does notmean that root canal obturation is less important,but that the success of endodontic treatmentdepends on meticulous root canal preparation.

The purpose of a root canal filling, as illustrat-ed in Figure 1, is to seal the root canal system toprevent:� Microorganisms from entering and reinfect-

ing the root canal system;� Tissue fluids from percolating back into the

root canal system and providing a culturemedium for any residual bacteria.1

In the past, attention has been focussed on theimportance of obtaining an hermetic apical seal.However, research has indicated that as well assealing the root canal system apically, it is equal-ly important to ensure that the coronal access tothe canal itself has a fluid-tight seal, to preventinfection from the oral cavity.2 Although numer-ous materials have been used to fill root canals,the most universally accepted is gutta-percha.

PROPERTIES OF ROOT CANAL FILLINGMATERIALS1

Ideally, a root canal filling should be:� Biocompatible� Dimensionally stable� Capable of sealing the canal laterally and

apically, conforming with the various shapesand contours of the individual canal

� Unaffected by tissue fluids and insoluble� Bacteriostatic

� Radiopaque� Easily removed from the canal if necessary.

To these properties may also be added, inca-pable of staining tooth or gingival tissues andeasily manipulated with ample working time.

Gutta-percha has a number of these desirableproperties. It is semisolid and can be compressedand packed to fill the irregular shapes of a rootcanal using lateral or vertical compaction tech-niques. It is non-irritant and dimensionally stable.It will become plastic when heated or when usedwith solvents (xylol, chloroform, eucalyptus oil). It is radiopaque and inert, and can be removedfrom the canal when required for post preparation.

8













Fig. 1 A radiograph of a well-obturated upper molar.



11p667-672.qxd 22/11/2004 15:14 Page 667

Its disadvantages are few. It is distorted bypressure and, consequently, can be forcedthrough the apical foramen if too much pressureis used, and it is not rigid and so can be difficultto use in smaller sizes. Also, a sealer is necessaryto fill in the spaces around the filling material.Root canal scalers were considered in Part 5.

Gutta-percha points are manufactured in var-ious forms. Standardised points match the ISOsizes, and have a 2% taper. Accessory pointshave fine tips and variable taper to facilitate andimprove lateral compaction. Greater taperpoints are available in 4% and 6% taper tomatch modern preparation techniques. Feather-tipped points permit individual and specificcone fitting to the prepared root canal.

REMOVAL OF SMEAR LAYERA smear layer is created by the action of metal-lic instruments on dentine, especially rotaryinstruments. It is composed of dentine filings,pulpal tissue remnants and may also containmicrobial elements. It may occlude dentinetubules thus harbouring bacteria, and may con-tain a bacterial plaque on the canal walls. It hasbeen shown that gutta-percha penetrates thedentine tubules when the smear layer has beenremoved.3

It is therefore suggested that the root canalshould be irrigated with an EDTA solution toremove the smear layer, followed by a final irri-gation with sodium hypochlorite, prior to dryingand obturating the canal.

FILLING TECHNIQUESThe studious reader will have noted the use ofthe word �compaction� rather than �condensa-tion�. In 1998, the American Endodontic Associ-ation recognised that this was a more appropri-ate term for the techniques used in obturation,and the term has been adopted in this text.4

Several techniques have been developed forplacing gutta-percha into the root canal system.

Nevertheless, the cold lateral compaction ofgutta-percha is still the most widely taught, andthe technique against which most others arecompared. However, as there is a demand forsaving teeth with complex pathology and rootcanal morphology (Fig. 2), it is sometimes easierto combine the merits of various techniques in ahybrid form to simplify the filling procedure.Studies have shown that these are satisfactory,although not always as easy as lateral com-paction to carry out.5,6

Before a root-filling is inserted, it is essentialthat the canals are dry. Any serous exudate fromthe periapical tissues indicates the presence ofinflammation. Calcium hydroxide may be usedas a root canal dressing until the next visit(calcium hydroxide BP mixed with purifiedwater or local anaesthetic solution to a thickpaste � see Part 9).

LATERAL COMPACTION OF GUTTA-PERCHAThe objective is to fill the canal with gutta-perchapoints (cones) by compacting them laterallyagainst the sides of the canal walls. The tech-nique requires selection of a master point, usu-ally one size larger than the master apical file,which should seat about 0.5 mm short of theworking length (Fig. 3a). If the point is loose atworking length, then either 1 mm should be cutfrom the tip and the point refitted to the canal,or a larger size point selected. It should be notedthat gutta-percha points can not be as accuratelymachined as metallic instruments. There may bevariance in the size stated, and if a matchedpoint does not fit a prepared canal it may beworth either trying another point from thepacket, or fitting the point in a measuring/sizinggauge, as illustrated in Figure 4.

Once the master point is fitted to length anddemonstrates a slight resistance to withdrawal(tug-back), accessory points are then insertedalongside the master point and compacted lat-erally with a spreader until the canal is sealed

PRACTICE

668 BRITISH DENTAL JOURNAL VOLUME 197 NO. 11 DECEMBER 11 2004

Fig. 2 These teeth with resorptivedefects may be impossible toobturate with conventionalmethods.

11p667-672.qxd 09/11/2004 14:07 Page 668

Fig. 6 Gutta-percha points should NOT be presented tothe operator by the surgery assistant with the tips dippedin sealer.

Fig. 5 Finger spreaders sized A to D with matchingaccessory points.

Fig. 4 An endodontic gauge foraccurately sizing gutta-perchapoints.

(Fig. 3b). The most simple system of accessorypoints designates these from A, the finest,through B and C to D, the largest, shown inFigure 5. As each point is used the prepared,flared, canal is becoming progressively wider,and the accessory points may therefore be usedsequentially from small to large. The resultantfilling appears above the access cavity as a spi-ral, with each point extruded slightly furtherout of the canal (Fig. 3c).

There are two main types of spreading instru-ments for compacting gutta-percha: long-handled spreaders and finger spreaders. Themain advantage of a finger spreader is that it isnot possible to exert the high lateral pressurethat might occur with long-handled spreaders.The chance of a root fracture is reduced and it istherefore a suitable instrument for beginners.

PROCEDURE1. The canal should be irrigated, cleaned and

dried.2. A master point is selected and fitted to the

canal as described above. It should be markedat working length, or grasped securely inendodontic locking tweezers.

3. The master point is coated with sealer andused to paste the canal walls with the sealer,

using an in-out movement, before seatingthe point home into the canal at full work-ing length.

4. A fine finger spreader is selected and the rub-ber stop set to working length. Place thespreader alongside the master point and com-pact using firm apical finger pressure only.Leave the spreader in situ for 30 seconds. Thisis important as continuous pressure from thespreader is required to deform the gutta-per-cha point against the canal walls and to over-come its elasticity.

5. Select an accessory point with lockingtweezers and dip its tip into sealer. Do notleave the points in sealer while working(Fig. 6) as a reaction may occur between thezinc oxide in the points (up to 80%) and theeugenol in the sealer, softening the pointsand making insertion difficult.

6. This stage is best carried out using twohands. Assuming the operator is right hand-ed, the tweezers holding the accessory pointare aligned above the tooth in the right hand,while the left hand rotates the spreader a fewtimes through an arc of 30�40° and with-draws it.

7. Immediately place the accessory pointalongside the master point. Any delay will

PRACTICE


Fig. 3 a) In cold lateral compaction, the master point should exhibit �tug-back� slightly short of the working lengths. (Paper points have been placed to protectthe other canals.) b) A finger spreader inserted alongside the master point, is left in place for 30 seconds. c) The spiral of successive accessory points in aneffective obturation.

a b c

11p667-672.qxd 09/11/2004 14:08 Page 669

Fig. 8 Machtou heat carriers/pluggers for warm compaction.

allow the master point to relax and spacewill be lost. Reinsert the spreader and laterallycompact both points.

8. Repeat the sequence using gradually largerspreaders and gutta-percha points until thecanal is filled.

9. Remove excess gutta-percha from the canalorifice with a heated plugger, and firmlycompact the remaining gutta-percha to sealthe coronal access to the canal (Fig. 7).

10. If post-space preparation is required it maybe carried out at this stage.

11. If not, a layer of resin-modified glass-ionomer cement should be applied over thegutta-percha and the floor of the accesscavity, completing the coronal seal.

12. A periapical radiograph should be taken oncompletion, using a long-cone parallel tech-nique. This is primarily for subsequent mon-itoring of healing by sequential radiographs,taken if possible in the same film-holder sys-tem to ensure reproducible and comparableexposures.

LATERAL COMPACTION OF WARM GUTTA-PERCHAA simple modification to the cold lateral com-paction technique is to apply heat to the gutta-percha. The softened material is easier to compactand will result in a denser root filling. However,finger spreaders will not retain heat sufficientlyfor this procedure, and specially designed heatcarriers should be used. The instruments illustrat-ed in Figure 8 have a sharp tip for lateralcompaction, and a blunt plugger tip for limitedvertical compaction of the softened gutta-percha.Electrically heated spreaders are also available.

It is important that the instruments are onlygently warmed. If the spreader is too hot it willmelt the gutta-percha, which will adhere to theinstrument and be withdrawn from the canal.

SINGLE GUTTA-PERCHA POINT AND SEALERWith the tendency to preparation techniques ofgreater taper, gutta-percha points of matchingtaper may be used. These fit the prepared canal sowell that some operators are using a single gutta-percha point and sealer. The only advantage ofthis technique is its simplicity. The disadvantage isthat the majority of sealers are soluble. As thecanal will not be fully filled in three dimensions,tissue fluids may leach out the sealer over time.This technique cannot therefore be recommended.

However, in difficult anatomical cases it may benecessary to create a custom-fitted cone. A slightly large cone is selected and the apical partsoftened, either by solvents such as chloroform,rectified turpentine or oil of eucalyptus, or byimmersion in hot water. The softened cone is fittedto working length with gentle pressure. The cone iscarefully marked for orientation, and the processrepeated until a satisfactory fit is obtained. Thecone should then be cleaned of all solvents, and thecanal obturated using sealer in the usual way.

As with all single-cone techniques, if theexcess sealer resorbs in the apical tissue fluids,microleakage may allow the ingress of tissue flu-ids, and failure of the stated criteria of obtura-tion. Really, an attempt should always be made toimprove the fit of a single cone with warm orcold lateral compaction of accessory points.

THERMATIC COMPACTION OF GUTTA-PERCHAIn 1979, McSpadden devised a handpiece-

PRACTICE


Fig. 7 The excess gutta-percha has been removed with a hot instrument, and the coronal filling has been compactedinto the root canal orifice a), prior to the placement of a glass ionomer coronal seal b).

a b

Fig. 9 a) Maillefer Gutta Condensors, with b) showingthe apically directed thread structure.

a b

11p667-672.qxd 09/11/2004 14:09 Page 670

Fig. 11 The System-B heat source.When the ring on the handpiece ispressed as shown the tip of theplugger is immediately heated to thetemperature selected.

PRACTICE


driven compactor, which is effectively an invert-ed Hedstroem file.7 Although no longer made,other similar devices, such as the gutta conden-sor (Fig. 9), are available. The frictional heat fromthe compactor plasticises the gutta-percha andthe blades drive the softened material into theroot canal under pressure. The main problemfound was lack of control over the apical portionof the gutta-percha, which may be extrudedthrough the apex in its softened state. To over-come this problem, the technique was modifiedby Tagger, who recommended laterally condens-ing a master point and two or three accessorypoints, and then using the condensor to plasticisethe gutta-percha in the coronal part of the canal.8

The laterally compacted material in the apicalhalf effectively prevents any apical extrusion.

The technique is particularly useful for therapid and effective obturation of the coronal partof a root canal after placement of an accurateapical seal.

HEATED GUTTA-PERCHA CARRIERSSeveral manufacturers now supply thesedevices, illustrated in Figure 10. Alpha-phasegutta-percha is attached to a rigid carrier, in avariation of the technique originally describedby Johnson in 1978.9 Most carriers are nowplastic. The excess material is removed, and thecarrier remains in the canal as a central core.The softened gutta-percha flows well in to canalaberrations, fins, etc., giving very good three-dimensional obturation.10 Success depends, aswith all techniques, upon thorough canal clean-ing and shaping. The carriers have a 4% taper,and an underprepared canal will be difficult ifnot impossible to obturate to working lengthwith these devices. A range of sizes is presented,and most systems employ a method of ensuringthe fit of the device before obturation is com-menced. This may either be a blank carrier withno gutta-percha attached, or preferably a file ofthe same dimensions as the carrier. The apicalpreparation may then be refined to ensure anaccurate fit of the device.

The canal should be cleaned and dried, and avery fine coating of sealer applied to the canalorifice only. Excess sealer may be extruded underhydraulic pressure through the apical foramen,with resultant pain and inflammation. In the

meantime the rubber stop on the selected deviceis set to working length, and the device placed ina special oven to soften the gutta-percha. Whenready, the device should be swiftly and smoothlyinserted to working length, and held in place fora few seconds. Using a high-speed bur the excesscarrier may be sectioned and removed from thecanal orifice, and a plugger used to compact thegutta-percha in this area. A layer of resin-modi-fied glass ionomer completes the obturation.

Some carriers are manufactured with a U-shaped cross-section to facilitate removal witha drill should retreatment be necessary. However,although it may be possible to drill out the carrier,this technique may not be appropriate if a postand core may be indicated in the future.

VERTICAL COMPACTION OF WARM GUTTA-PERCHAHeated gutta-percha has been shown to flowextremely well into all canal irregularities. It isparticularly useful in situations such as internalresorption, C-shaped canals, and those with finsor webs. As referred to earlier, when the smearlayer is removed the gutta-percha has beenshown to penetrate dentine tubules.3 This tech-nique is now considered the gold standard forendodontic obturation. The principle of verticalcompaction of increments of warm gutta-perchawas first described by Schilder in 1967.11

Although delivering excellent results, the methodwas difficult to master and time-consuming.

The state of the art at present is the methodfirst described by Buchanan employing theSystem-B heat source (Fig. 11), which delivers aprecise heat to the tip of the plugger.12 A non-standardised (4%, 6% or feathered tip) gutta-percha cone is carefully fitted to the canal.Using a selected plugger, a continuous wave ofheat is applied to soften and downpack a cone,resulting in very well-compacted obturation ofthe apical portion of the canal. The remainder ofthe canal may be obturated by further incre-ments, or by another method. Briefly, thetechnique is as follows.1. Fit a gutta-percha cone and mark it at work-

ing length.2. Select one of the System-B pluggers that

binds in the canal 5�7 mm short of the work-ing length. Set a rubber stop at this level, and

Fig. 10 An example of a Thermafil device a), a heatedgutta-percha carrier, with an oven necessary for accuratesoftening b). The U-shaped cross-section of the plasticcarrier is shown in c).

a

c

b

11p667-672.qxd 09/11/2004 14:10 Page 671

`

PRACTICE


select a conventional plugger to fit at thislength as well.

3. Dry the canal with paper points.4. Apply a thin layer of sealer to the apical

third of the selected cone, and insert it toworking length.

5. Set the temperature of the System-B at200°C, with full power. Heat is applied to theplugger via the finger-tip microswitch, andthe part of the cone extruding from the canalorifice is seared off.

6. The tip of the plugger is placed in the centreof the gutta-percha cone, heat applied, andthe plugger is carefully pushed down thecanal in one slow, even movement to thedepth marked. This should take about 3 sec-onds. The heat is turned off, and the pluggerheld in place for a further 10 seconds.

7. With a brief burst of heat to separate theplugger from the gutta-percha, the plugger isremoved from the canal. It is usually foundto bring with it the coronal portion of thegutta-percha as well.

8. The apical part may now be further compactedwith conventional hand pluggers.

9. The coronal part of the canal may now beobturated with either injectable gutta-percha, described later, or further use of theSystem-B as follows.

10. A small length of gutta-percha, about 7 mm,is cut from a further accessory point, coatedwith sealer and inserted into the canal.

11. With the heat source turned down to 100°C,otherwise this gutta-percha will not stay inthe canal, a short burst of heat is applied, thegutta-percha compacted, and the pluggerremoved as before. Hand pluggers may beused to further compact this and anysubsequent increments required.

12. A layer of resin-modified glass-ionomercement is applied over the obturation, and apost-operative radiograph is exposed asnormal.

INJECTABLE GUTTA-PERCHADevices for injecting softened gutta-percha havebeen available for some time, but in the past havesuffered from techniques which led to difficultyin accurate apical placement. The latest of these,the Obtura-II, has recently gained acceptance byendodontists. The machine resembles a glue-gun.Pellets of alpha-phase gutta-percha are softenedat about 200°C in the handpiece, and extrudedthrough a heated silver needle (Fig. 11). A wide,well-prepared canal is a prerequisite. Althoughthe manufacturers describe a procedure for total

obturation of a root canal, apical control can bedifficult. The machine has become accepted fortwo specific procedures.

CORONAL BACK-FILLINGThe previously described System-B achieves anexcellent and controlled obturation of the apical5�7 mm of the root canal. At this point the canalis quite wide, and can accept the tip of the Obtu-ra�s needle. A film of sealer is applied to thecanal wall. The machine is heated to 200°C. Asmall amount of the warm gutta-percha shouldbe extruded to warm the needle and discarded.The needle is then quickly introduced to thecanal. If this part of the protocol is not followed,a void may result between the two parts of thefilling. The trigger is activated and thermoplasti-cised gutta-percha extruded into the canal, gen-tly pushing the needle out. Once the canal isfilled conventional pluggers may be used tocompact the gutta-percha, which is finallysealed with glass ionomer as usual.

OPEN APICESThe open apex, particularly in paediatricendodontics, can present a problem if it is toowide to permit the creation of a custom-fittedcone. A method of using the Obtura-II has beendescribed whereby an increment of gutta-perchais applied to the canal close to the apex, andgently compacted with pluggers. A rapid-devel-oping radiograph is exposed to verify the posi-tion of the apical seal, and further compactioncarried out if required. Once the apical seal isintact the remainder of the canal may be filledwith the Obtura-II in the normal way.

1. European Society of Endodontology. Consensus reportfor the European Society of Endodontology on qualityguidelines for endodontic treatment. Int Endod J 1994;27: 115�124.

2. Saunders W P, Saunders E M. Coronal leakage as acause of failure in root canal therapy: a review. EndodDent Traumatol 1994; 10: 105�108.

3. Gutmann J L. Adaptation of injected thermoplasticisedgutta percha in the absence of the dentinal smear layer.Int Endod J 1993; 26: 87�92.

4. American Association of Endodontists. Glossary,contemporary terminology for endodontics, edition 6.Chicago: American Association of Endodontists, 1998.

5 Gee J Y. A comparison of five methods of root canalobturation by dye penetration. Aust Dent J 1987; 32: 279�284.

6. Haas S B, Campbell A D, Hicks M L, Pelleu G B. A comparison of four root canal filling techniques.J Endod 1989; 15: 596�601.

7. McSpadden J T. Presentation to the meeting of theAmerican Association of Endodontists, Atlanta,Georgia, USA 1979.

8. Tagger M, Tanse A, Katz A, Korzen B H. Evaluation ofthe apical seal produced by a hybrid root canal fillingmethod, combining lateral condensation and thermalcompaction. J Endod 1984; 10: 299�303.

9. Johnson W B. A new gutta-percha technique. J Endod1978; 4: 184�188.

10. Gutman J L, Saunders W P, Saunders E M, Nguyen L. An assessment of the plastic thermal obturationtechnique. II Material adaptation and sealability. Int Endod J 1993; 26: 179�183.

11. Schilder H. Filling root canals in three dimensions.Dent Clin North Am 1967; 11: 723�744.

12. Buchanan L S. The continuous wave of obturationtechnique: �centred� condensation of warm gutta percha in 12 seconds. Dent Today 1996; 15: 60�87.

Fig. 12 Heated alpha-phase gutta-percha beingextruded from the silverneedle of the Obtura IImachine.

11p667-672.qxd 09/11/2004 14:10 Page 672


PRACTICE

Endodontics: Part 9Calcium hydroxide, root resorption, endo-perio lesionsP. Carrotte1

For more than 70 years calcium hydroxide has played a major role in endodontic therapy, although many of its functions arenow being taken over by the recently introduced material MTA. Calcium hydroxide may be used to preserve the vital pulp ifinfection and bleeding are controlled; to repair root fractures, perforations, open apices and root resorptions. Endo-periolesions are complex and the correct diagnosis is essential if treatment is to be successful. However, root canal treatment willalways be the first phase in treating such lesions.

● Calcium hydroxide is used in both the preservation of the vital pulp and the disinfection ofthe prepared root canal system.

● To achieve success in direct pulp capping a strict aseptic regime must be followed.● Various forms of root resorption, their aetiology and treatment, are considered.● The Simon, Glick and Frank classification of endodontic/periodontic lesions is presented and

discussed.

I N B R I E F

CALCIUM HYDROXIDECalcium hydroxide was originally introduced tothe field of endodontics by Herman1 in 1930 asa pulp-capping agent, but its uses today arewidespread in endodontic therapy. It is the mostcommonly used dressing for treatment of thevital pulp. It also plays a major role as an inter-visit dressing in the disinfection of the rootcanal system.

Mode of actionA calcified barrier may be induced when calci-um hydroxide is used as a pulp-capping agentor placed in the root canal in contact withhealthy pulpal or periodontal tissue. Becauseof the high pH of the material, up to 12.5, asuperficial layer of necrosis occurs in the pulpto a depth of up to 2 mm. Beyond this layeronly a mild inflammatory response is seen, andproviding the operating field was kept free ofbacteria when the material was placed, a hardtissue barrier may be formed. However, the cal-cium ions that form the barrier are derivedentirely from the bloodstream and not from thecalcium hydroxide.2 The hydroxyl group isconsidered to be the most important compo-nent of calcium hydroxide as it provides analkaline environment which encourages repairand active calcification. The alkaline pHinduced not only neutralises lactic acid fromthe osteoclasts, thus preventing a dissolutionof the mineral components of dentine, butcould also activate alkaline phosphataseswhich play an important role in hard tissueformation. The calcified material which is pro-duced appears to be the product of both odon-

toblasts and connective tissue cells and may betermed osteodentine. The barrier, which iscomposed of osteodentine, is not always com-plete and is porous.

In external resorption, the cementum layer islost from a portion of the root surface, whichallows communication through the dentinaltubules between the root canal and the peri-odontal tissues. It has been shown that the dis-association coefficient of calcium hydroxide of0.17 permits a slow, controlled release of bothcalcium and hydroxyl ions which can diffusethrough dentinal tubules. Tronstad et al. demon-strated that untreated teeth with pulpal necrosishad a pH of 6.0 to 7.4 in the pulp dentine andperiodontal ligament, whereas, after calciumhydroxide had been placed in the canals, theteeth showed a pH range in the peripheraldentine of 7.4 to 9.6.3

Tronstad et al. suggest that calcium hydroxidemay have other actions; these include, for exam-ple, arresting inflammatory root resorption andstimulation of healing.3 It also has a bactericidaleffect and will denature proteins found in theroot canal, thereby making them less toxic.Finally, calcium ions are an integral part of theimmunological reaction and may activate thecalcium-dependent adenosine triphosphatasereaction associated with hard tissue formation.

PresentationCalcium hydroxide can be applied as a hard set-ting cement, as a paste or as a powder/liquidmixture, depending on the treatment. Variousproprietary brands are available, (Fig. 1),although ordinary calcium hydroxide powder BP

9







6. Rubber dam and accesscavitities










12p735-743.qxd 19/11/2004 11:40 Page 735

may be purchased from a chemist and mixedwith purified water. Because of the antibacterialeffect of calcium hydroxide, it is not necessaryto add a germicide. The advantages of using cal-cium hydroxide in this form are that variableconsistencies may be mixed and a pH of about12 is achieved, which is higher than that of proprietary brands.

Root canal sealers containing calcium hydrox-ide are available, and are discussed in Part 5.

Clinical uses and techniquesThe clinical situations where calcium hydroxidemay be used in endodontics are discussed belowand the techniques described. The method ofapplication of calcium hydroxide to tissue isimportant if the maximum benefit is to begained. When performing pulp capping, pulpo-tomy or treatment to an open apex in a pulplesstooth, the exposed tissue should be cleanedthoroughly, any haemorrhage arrested by irri-gation with sterile saline and the use of sterilecotton wool pledgets. The calcium hydroxideshould be placed gently directly on to the tissue,with no debris or blood intervening.4 A calciumhydroxide cement may be applied to protect thepulp in a deep cavity as discussed later.

Routine canal medicationThe indications for intervisit dressing of the rootcanal with calcium hydroxide have been con-sidered in Part 7. There are two methods ofinserting calcium hydroxide paste into the rootcanal, the object being to fill the root canalcompletely with calcium hydroxide so that it isin contact with healthy tissue. Care should betaken to prevent the extrusion of paste into theperiapical tissues, although if this does occurhealing will not be seriously affected.

Proprietary brandsThe root canal system is first prepared and thendried. A spiral root canal filler is selected andpassively tried in the canal. It must be a loose fitin the canal over its entire length, or fracturemay occur, as seen in Figure 2. The workinglength of the canal should be marked on theshank with either marking paste or a rubberstop. The author prefers the blade type of filler

as these are less prone to fracture. The paste ofchoice is spread evenly on the shank. The spiralfiller is inserted into the canal and �wiped�around the walls to reduce air bubble formation.Using a standard handpiece with low rpm, theroot canal is filled with paste. Several applica-tions may be required. A large paper point maybe used to condense the material into the canal,and this will also absorb excess moisture. A pledget of cotton wool is pressed into the pulpchamber so that the paste is condensed furtherand the access cavity sealed.

Powder�liquidThe powder and liquid are mixed on a glass slabwith a spatula to form a thick paste. Althoughsterile water may be used, local anaestheticsolution is more readily available in the surgery.The material may be applied using a spiral rootcanal filler as described earlier, however somepractitioners prefer to use the small plastic tubewith a long fine point illustrated in Part 7,Figure 14. The mixed material is loaded into thetube and extruded directly deep in the canal. A large paper point may again be used to con-dense the material further, and absorb excesswater making the procedure easier and the fill-ing more dense (Fig. 3). A firmer paste may bemade by adding powder to a proprietary brandof calcium hydroxide paste.

Of utmost importance in endodontics is thetemporary coronal seal which prevents leakageand (re)contamination of the canal system.Intermediate restorative material (IRM), orglass-ionomer cement are useful for periods ofover 7�10 days; for shorter periods, zinc oxide,Cavit or other proprietary material may be used,as described in Part 5.

Radiographic appearanceA root canal filled with calcium hydroxideshould appear on a radiograph as if it were com-pletely sclerosed, as in Figure 4. The material isprone to dissolution, which would appear on aradiograph as voids in the canal. In the past, theaddition of more radiopaque agents such as bar-ium sulphate has been recommended. As thesematerials may be resorbed more slowly than thecalcium hydroxide a false picture may be given,and this practice has largely been discontinued.

Indirect pulp cappingThe treatment of the deep carious lesion whichhas not yet involved the pulp has for some timebeen the subject of intense debate. Someresearchers recommend the use of a calciumhydroxide lining to stimulate odontoblasts andincrease dentine formation.4,5 Other workershave claimed that this does not occur.6,7 Someworkers still recommend that infected cariousdentine is removed but a layer of softened steriledentine may be left over the intact vital pulp.8

Most endodontic texts, (for example, see Refer-ences 9 and 10) recommend that all softeneddentine should be removed and the pulp dealtwith accordingly.

PRACTICE


Fig. 1 One of various proprietarybrands of calcium hydroxideavailable

Fig. 2 Spiral rootfillers are prone tofracture if their passivefit in the root canal hasnot been verifiedbefore use

12p735-743.qxd 19/11/2004 11:40 Page 736

There is still controversy, however, over thecorrect treatment of a deep, caries free, cavity,lying close to the pulp. As alluded to in Part 1, theessential treatment is to ensure that there can beno bacterial contamination of the pulp via theexposed dentine tubules.11 This may be achievedby either a lining of glass-ionomer cement, or theuse of an acid-etched dentine bonding system.Some workers have recommended washing thecavity with sodium hypochlorite to further disin-fect the dentine surface, and this seems an emi-nently sensible suggestion. Until further researchprovides conclusive evidence for or against, how-ever, the use of an indirect pulp cap of calciumhydroxide is recommended in these situations.The calcium hydroxide cement provides a bacteri-cidal effect on any remaining bacteria and mayencourage the formation of secondary dentineand of a dentine bridge. It is certainly no longerconsidered necessary to reopen the cavity at alater date to confirm healing.

Direct pulp cappingThe aim of direct pulp capping is to protect thevital pulp which has been exposed during cavitypreparation, either through caries or trauma. Themost important consideration in obtaining suc-cess is that the pulp tissue remains uncontami-nated. In deep cavities, when an exposure may beanticipated, all caries should be removed beforeapproaching the pulpal aspect of the cavity floor.If an exposure of the pulp occurs in a cariousfield the chances of successful pulp capping areseverely compromised. A rubber dam should beapplied as soon as pulp capping is proposed. Thepulp should be symptom-free and uninfected,and the exposure should be small. Before com-mencing large restorations in suspicious teeth itmay be prudent to test the vitality of the toothwith an electronic pulp tester, and also to exposea radiograph to ensure that there is no evidenceof pulpal or periapical pathology. The radiographmay in fact be more valuable, as misleadingresults may occur when using an electric pulptester on compromised multirooted teeth.

If the above criteria have been met and pulpcapping is indicated, the cavity should be cleanedthoroughly, ideally with sodium hypochloritesolution, and pulpal haemorrhage arrested with

sterile cotton pledgets. Persistent bleeding indi-cates an inflamed pulp, which may not respond totreatment. After placing the calcium hydroxide,the area must be sealed against bacterial ingress,preferably with a glass-ionomer lining.

Partial pulpotomyAlthough the technique of pulpotomy is indicatedfor immature teeth with open apices, as describedin Part 10, it cannot be recommended routinely inmature teeth. However, the technique of partialpulpotomy (a procedure between pulp cappingand pulpotomy) was introduced by Cvek and hasbeen shown to be very successful in the treatmentof traumatically exposed pulps.12,13 The exposedpulp and surrounding dentine is removed underrubber dam isolation with a high-speed diamonddrill and copious irrigation using sterile saline, toa depth of about 2 mm. Haemostasis is achievedand the wound dressed with a non-setting calci-um hydroxide paste, either powder and sterilesaline or a proprietory paste. The cavity is sealedwith a suitable lining, such as resin-modifiedglass-ionomer cement, and restored convention-ally. The tooth should be carefully monitored.

Mineral trioxide aggregateAlthough the majority of practitioners will usecalcium hydroxide routinely and effectively forpulp capping and various repairs to the root,Mineral trioxide aggregate (MTA) is increasinglyused in specialist and some general practices. Thematerial is described briefly in Part 5, and theapplication discussed in Part 11. Early research asa root-end filling material showed unparalleledresults, and workers have since reported similarsuccess in other endodontic procedures, with noresulting inflammation, and deposition ofcementum over the restorative material.14�16

MTA can be used in place of hard-setting calciumhydroxide in all these pulp-capping procedures.

Root-end induction (apexification)The cases in which partial or total closure of anopen apex can be achieved are:1. vital radicular pulp in an immature tooth

pulpotomy (see Part 10);2. pulpless immature tooth with or without a

periapical radiolucent area.

PRACTICE


Fig. 3 A paper point may be used to condense thecalcium hydroxide in the canal and remove excessmoisture

Fig. 4 A radiograph showing root canal system filled withcalcium hydroxide, which has the same radio-density asthe dentine. Any part of the canal not filled with thepaste appears as a void

12p735-743.qxd 19/11/2004 11:41 Page 737

The success of closure is not related to the ageof the patient. It is not possible to determinewhether there would be continued root growthto form a normal root apex or merely the forma-tion of a calcific barrier across the apical end ofthe root. The mode of healing would probably berelated to the severity and duration of the peri-apical inflammation and the consequent survival of elements of Hertwig�s sheath.

Inducing apical closure may take anythingfrom 6 to 18 months or occasionally longer. It isnecessary to change the calcium hydroxide dur-ing treatment; the suggested procedure is givenbelow:First visit � Thoroughly clean and prepare theroot canal. Fill with calcium hydroxide.

Second visit � 2 to 4 weeks later, remove the cal-cium hydroxide dressing with hand instrumentsand copious irrigation. Care should be taken notto disturb the periapical tissue. The root canal isdried and refilled with calcium hydroxide.Third visit � 6 months later, a periapical radi-ograph is taken and root filled if closure is com-plete. This may be checked by removing the cal-cium hydroxide and tapping with a paper pointagainst the barrier. Repeat the calcium hydroxidedressing if necessary.Fourth visit � After a further 6 months anotherperiapical radiograph is taken, and the toothroot-filled if closure is complete. If the barrier isstill incomplete the calcium hydroxide dressingis repeated.Fifth visit � This should take place 3 to 6 monthslater. The majority of root closures will havebeen completed by this time (Fig. 5).

Once again, however, reference must be madeto the increasing use of MTA for root-endclosure and other such endodonticprocedures.17

Horizontal fracturesHorizontal fractures of the root may be treated,provided the fracture lies within the alveolarbone and does not communicate with the oralcavity. The blood supply may have been inter-rupted at the fracture site only, so that the apicalfragment remains vital. In these cases, the coro-nal portion of the root can be treated as an openapex. Cvek states that healing with a calcific bar-rier can be achieved using calcium hydroxide.15

Iatrogenic perforationsIatrogenic perforations are caused by an instru-ment breaching the apex or wall of the rootcanal; probably the most common occurrence isduring the preparation of a post space (Fig. 6).Partial or complete closure by hard tissue may beinduced with calcium hydroxide, provided theperforation is not too large, lies within the cre-stal bone and does not communicate with theoral cavity. Treatment should begin as soon aspossible, adopting the same procedure as forroot-end induction. Closure of perforationsusing calcium hydroxide takes considerablylonger than root-end induction in most cases.An alternative technique, if the perforation canbe visualised with the use of a surgical micro-scope, would be direct repair with mineraltrioxide aggregate.

If foreign bodies in the form of root-fillingmaterials, cements or separated instrumentshave been extruded into the tissues, healing withcalcium hydroxide is unlikely to occur and asurgical approach is recommended (Part 11).

ROOT RESORPTIONSeveral different types of resorption are recog-nised: some are isolated to one tooth and slowspreading, others are rapid, aggressive and mayinvolve several teeth. Resorption is initiatedeither from within the pulp, giving rise to

PRACTICE


Fig. 5 A calcific barrier is evidentfollowing calcium hydroxidetherapy in a case with an open apex

Fig. 6 The mesial wall of the rootcanal at tooth UL1 (21) has beenperforated during post spacepreparation, causing a lateralperiodontitis

12p735-743.qxd 19/11/2004 11:43 Page 738

PRACTICE


internal resorption, or from outside the tooth,where it is termed external resorption.

The aetiology of resorption has been describedby Tronstad who also presented a new classifica-tion.18 In Tronstad�s view, the permanent teethare not normally resorbed, the mineralised tis-sues are protected by predentine and odonto-blasts in the root canal and by precementum andcementoblasts on the root surface. If the preden-tine or precementum becomes mineralised, or, inthe case of the precementum, is mechanicallydamaged or scraped off, multinucleated cellscolonise the mineralised or denuded surfacesand resorption ensues. Tronstad refers to thistype of resorption as inflammatory, which maybe transient or progressive. Transient inflamma-tory resorption will repair with the formation ofa cementum-like tissue, unless there is continu-ous stimulation. Transient root resorption willoccur in traumatised teeth or teeth that haveundergone periodontal treatment or orthodon-tics. Progressive resorption may occur in thepresence of infection, certain systemic diseases,mechanical irritation of tissue or increased pressure in tissue.

Internal resorptionThe aetiology of internal resorption is thought tobe the result of a chronic pulpitis. Tronstadbelieves that there must be a presence of necrotictissue in order for internal resorption to becomeprogressive.18 In most cases, the condition ispain-free and so tends to be diagnosed duringroutine radiographic examination. Chronic pul-pitis may follow trauma, caries or iatrogenic pro-cedures such as tooth preparation, or the causemay be unknown. Internal resorption occursinfrequently, but may appear in any tooth; thetooth may be restored or caries-free. The defectmay be located anywhere within the root canalsystem. When it occurs within the pulp chamber,it has been referred to as �pink spot� because the

enlarged pulp is visible through the crown. Thetypical radiographic appearance is of a smoothand rounded widening of the walls of the rootcanal. If untreated, the lesion is progressive andwill eventually perforate the wall of the root,when the pulp will become non-vital (Fig. 7a).The destruction of dentine may be so severe thatthe tooth fractures.

The treatment for non-perforated internalresorption is to extirpate the pulp and prepareand obturate the root canal. An inter-appoint-ment dressing of calcium hydroxide may be usedand a warm gutta-percha filling technique helpsto obturate the defect (Fig. 7b). The main prob-lem is the removal of the entire pulpal contentsfrom the area of resorption while keeping theaccess to a minimum. Hand instrumentationusing copious amounts of sodium hypochloriteis recommended. The ultrasonic technique ofroot canal preparation may provide a cleanercanal as the acoustic streaming effect removescanal debris from areas inaccessible to the file.The prognosis for these teeth is good and theresorption should not recur.

The treatment of internal resorption that hasperforated is more difficult, as the defect must besealed. When the perforation is inaccessible to asurgical approach, an intracanal seal may beachieved with a warm gutta-percha technique.Alternatively, the root canal and resorbed areamay be obturated using mineral trioxide aggre-gate. Before the final root filling is placed, acalcium hydroxide dressing is recommended.

External resorptionThere are many causes of external resorption,both general and local.19 An alteration of the deli-cate balance between osteoblastic and osteoclasticaction in the periodontal ligament will produceeither a build-up of cementum on the root surface(hypercementosis) or its removal together withdentine, which is external resorption.

aFig. 7 a) Typical view of internalresorption, showing a smooth,rounded widening of the root canal.b) A warm gutta-percha techniquewill obturate the defect fully

b

12p735-743.qxd 19/11/2004 11:44 Page 739

`

PRACTICE


Resorption may be preceded by an increase inblood supply to an area adjacent to the root sur-face. The inflammatory process may be due toinfection or tissue damage in the periodontalligament, or, alternatively post-traumatic hyper-plastic gingivitis and cases of epulis. It has beensuggested that osteoclasts are derived fromblood-borne monocytes. Inflammation increasesthe permeability of the associated capillary ves-sels, allowing the release of monocytes whichthen migrate towards the injured bone and/orroot surface. Other causes of resorption includepressure, chemical, systemic diseases andendocrine disturbances.

Six different types of external resorption havebeen recognised and recorded in the literature.

Surface resorptionSurface resorption is a common pathologicalfinding.20 The condition is self-limiting andundergoes spontaneous repair. The root surfaceshows both superficial resorption lacunae andrepair with new cementum. The osteoclasticactivity is a response to localised injury to theperiodontal ligament or cementum. Surfaceresorption is rarely evident on the radiograph.

Inflammatory resorptionInflammatory resorption is thought to be causedby infected pulp tissue. The areas affected will bearound the main apical foramina and lateralcanal openings. The cementum, dentine and adja-cent periodontal tissues are involved, and a radi-olucent area is visible radiographically. In thecase illustrated in Figure 8 the root canal wassclerosed following trauma at an early age. Rootplaning during periodontal treatment whichremoved the cementum layer appeared to be theinitiating factor for inflammatory resorptionaround a lateral canal. The root canal was identified and root canal treatment carried out,followed by external surgical repair of the lesion.

Replacement resorptionReplacement resorption is a direct result of trau-ma and has been described in detail byAndreasen.21 A high incidence of replacementresorption follows replantation and luxation,particularly if there was delay in replacing thetooth or there was an accompanying fracture ofthe alveolus. The condition has also been referredto as ankylosis, because there is gradual resorp-tion of the root, accompanied by the simultane-ous replacement by bony trabeculae. Radi-ographically, the periodontal ligament space willbe absent, the bone merging imperceptibly withthe dentine.

Once started, this condition is usually irre-versible, leading ultimately to the replacementof the entire root. Calcium hydroxide treatmentis unlikely to help in the treatment of this type ofresorption.

Pressure resorptionPressure on a tooth can eventually cause resorp-tion provided there is a layer of connective tissuebetween the two surfaces. Pressure can be causedby erupting or impacted teeth, orthodonticmovement, trauma from occlusion, or pathologi-cal tissue such as a cyst or neoplasm. Resorptiondue to orthodontic treatment is relatively com-mon. One report of a 5�10-year follow-up aftercompletion of orthodontic treatment found anincidence of 28.8% of affected incisors.22

It may be assumed that the pressure exertedevokes a release of monocyte cells and the sub-sequent formation of osteoclasts. If the cause ofthe pressure is removed, the resorption will bearrested.

Systemic resorptionThis may occur in a number of systemic diseasesand endocrine disturbances: hyperparathy-roidism, Paget�s disease, calcinosis, Gaucher�sdisease and Turner�s syndrome. In addition,

Fig. 8 a) Inflammatory resorptionfollowing periodontal treatment of atooth with a necrotic pulp. b) Rootcanal treatment has been carriedout, and the lesion repaired by asurgical approach

ba

12p735-743.qxd 19/11/2004 11:45 Page 740

PRACTICE


resorption may occur in patients followingradiation therapy.

Idiopathic resorptionThere are many reports of cases in which, despiteinvestigation, no possible local or general causehas been found. The resorption may be confinedto one tooth, or several may be involved. The rateof resorption varies from slow, taking place overyears, to quick and aggressive, involving largeamounts of tissue destruction over a few months.The site and shape of the resorption defect also varies. Two different types of idiopathicresorption have been described.

Apical resorption is usually slow and mayarrest spontaneously; one or several teeth maybe affected, with a gradual shortening of theroot, while the root apex remains rounded. Cer-vical external resorption takes place in the cervi-cal area of the tooth. The defect may form eithera wide, shallow crater or, conversely, a burrow-ing type of resorption. This latter type has beendescribed variously as peripheral cervical resorp-tion, burrowing resorption, pseudo pink spot,resorption extra camerale and extracanal invasive.

There is a small defect on the external surfaceof the tooth; the resorption then burrows deepinto the dentine with extensive tunnel-shapedramifications. It does not, as a rule, affect thedentine and predentine in the immediate vicinityof the pulp. This type of resorption is easily mis-taken for internal resorption. Cervical resorptionmay be caused by chronic inflammation of theperiodontal ligament or by trauma. Both types ofcervical resorption are best treated by surgicalexposure of the resorption lacunae and removalof the granulation tissue. The resorptive defect isthen shaped to receive a restoration.

THE PERIO-ENDO LESIONThe differential diagnosis of perio-endo lesionshas become increasingly important as thedemand for complicated restorative work hasgrown. Neither periodontic nor endodontictreatment can be considered in isolation as clini-cally they are closely related and this must influ-ence the diagnosis and treatment. The influenceof infected and necrotic pulp on the periapicaltissues is well known, but there remains muchcontroversy over the effect that periodontal disease could have on a vital pulp.

Examination of the anatomy of the tooth showsthat there are many paths to be taken by bacteriaand their toxic products between the pulp and theperiodontal ligament. Apart from the main apicalforamina, lateral canals exist in approximately50% of teeth, and may be found in the furcationregion of permanent molars.23 Seltzer et al.observed inter-radicular periodontal changes indogs and monkeys after inducing pulpotomiesand concluded that noxious material passedthrough dentinal tubules in the floor of the pulpchamber.24 In addition to dentinal tubules,microfractures are often present in teeth, allowingthe passage of microorganisms. Clinically, it iscommon to see cervical sensitivity.

The controversy concerning the effect of peri-odontal disease on the pulp ranges betweenthose who believe that pulpitis or pulp necrosisor both can occur as a result of periodontalinflammation, to those who state categoricallythat pulpal changes are independent of the statusof the periodontium. In the author�s opinion,Belk and Gutmann present the most rationalview, which is that periodontal disease maydamage pulp tissue via accessory or lateralcanals, but total pulpal disintegration will notoccur unless all the main apical foramina areinvolved by bacterial plaque (Fig. 9).25

The problem that faces the clinician treatingperio-endo lesions is to assess the extent of the dis-ease and to decide whether the tooth or the peri-odontium is the primary cause. Only by carryingout a careful examination can the operator judgethe prognosis and plan the treatment.26 There areseveral ways in which perio-endo lesions can beclassified; the one given below is a slight modifica-tion of the Simon, Glick and Frank classification.27

Classification of perio-endo lesionsClass 1. Primary endodontic lesion draining throughthe periodontal ligamentClass l lesions present as an isolated periodontalpocket or swelling beside the tooth. The patientrarely complains of pain, although there willoften be a history of an acute episode. The causeof the pocket is a necrotic pulp draining throughthe periodontal ligament. The furcation area ofboth premolar and molar teeth may be involved.Diagnostically, one should suspect a pulpallyinduced lesion when the crestal bone levels onboth the mesial and distal aspects appear normaland only the furcation shows a radiolucent area.

Class 2. Primary endodontic lesion with secondaryperiodontal involvementIf left untreated, the primary lesion may becomesecondarily involved with periodontal break-down. A probe may encounter plaque or calculusin the pocket. The lesion will resolve partiallywith root canal treatment but complete repairwill involve periodontal therapy.

Fig. 9 A severe endo-perio lesionthat may require root resection

12p735-743.qxd 19/11/2004 11:46 Page 741

PRACTICE


Class 3. Primary periodontal lesionsClass 3 lesions are caused by periodontal diseasegradually spreading along the root surface. Thepulp, although compromised, may remain vital.However, in time there will be degenerativechanges. The tooth may become mobile as theattachment apparatus and surrounding bone aredestroyed, leaving deep periodontal pocketing.Perodontal disease will usually be seen else-where in the mouth unless there are local predis-posing factors such as a severely defectiverestoration or proximal groove.

Class 4. Primary periodontal lesions with secondaryendodontic involvementA Class 3 lesion progresses to a Class 4 lesionwith the involvement of the main apical forami-na or possibly a large lateral canal. It is some-times difficult to decide whether the lesion isprimarily endodontic with secondary periodon-tal involvement (Class 2), or primarily peri-odontal with secondary endodontic involve-ment (Class 4), particularly in the late stages. Ifthere is any doubt, the necrotic pulp should beremoved; any improvement in the periodontaldisease suggests that the classification was infact of a Class 2 lesion.

Root removal and root canal treatmentTo prevent further destruction of the periodon-tium in multirooted teeth, in may be necessaryto remove one or occasionally two roots. As thistreatment will involve root canal therapy andperiodontal surgery, the operator must considerthe more obvious course of treatment, which isto extract the tooth and provide some form offixed prosthesis. As a guide, the following fac-tors should be considered before root resection:1 Functional tooth. The tooth should be a

functional member of the dentition.2 Root filling. It should be possible to provide

root canal treatment which has a good prog-nosis. In other words, the root canals must befully negotiable.

3 Anatomy. The roots should be separate withsome inter-radicular bone so that theremoval of one root will not damage theremaining root(s). Access to the tooth mustbe sufficient to allow the correct angulationof the handpiece to remove the root. A smallmouth may contra-indicate the procedure.

4 Restorable. Sufficient tooth structure mustremain to allow the tooth to be restored. Thefinishing line of the restoration must beenvisaged to ensure that it will be cleansableby the patient.

5 Patient suitability. The patient must be asuitable candidate for the lengthy operativeprocedures and be able to maintain a highstandard of oral cleanliness around the sectioned tooth.

A tooth that requires a root to be resected willneed root canal treatment. The surgery must beplanned with care, particularly with respect to

the timing of the root treatment. Ideally, thetooth should be root filled prior to surgery,except for the root to be resected. The pulp isextirpated from the root to be removed, thecanal widened in the coronal 2�3 mm andrestored with a permanent material. This meansa retrograde filling will not have to be placed atthe time of surgery � a procedure which is diffi-cult to perform owing to poor access and bloodcontamination of the filling and the likelihoodof the restorative material falling into the socket.

1. Hermann B W. Dentinobleration der Wurzelkanalenach der Behandlung mit Kalcium. ZahnarztRundschau 1930; 39: 888.

2. Sciaky I, Pisanti S. Localisation of calcium placed overamputated pulps in dogs� teeth. J Dent Res 1960; 39:1128�1132.

3. Tronstad L, Andreason J O, Hasselgren G, Kristerson L,Riis I. PH changes in dental tissues after root canalfilling with calcium hydroxide. J Endod 1981; 7: 17�21.

4. Hasselgren G, Tronstad L. Enzyme activity in the pulpfollowing preparation of cavities and insertion ofmedicaments in cavities in monkeys. Acta OdontolScand 1978; 35: 289�295.

5. Tronstad L, Mjør I A. Pulp reactions to calciumhydroxide containing materials Oral Surgery, OralMedicine, Oral Pathology 1972; 33: 961�965

6. Bergenholtz G, Reit C. Reactions of the dental pulp tomicrobial provocation of calcium hydroxide treateddentine. Scand J Dent Res 1980; 88: 187�192.

7. Warfvinge J, Rozell B, Hedström K G. Effect of calciumhydroxide treated dentine on pulpal responses. Int Endod J 1987; 20: 183�193.

8. Kidd E A M, Banerjee A. What is Absence of Caries. InAlbrektsson TO, Bratthall D, Glantz P-O J and LindheJT, Tissue Preservation in Caries Treatment. London:Quintessence Books, 2001.

9. Kim S, Trowbridge H, Suda H. Chapter 15 in Cohen Sand Burns R C, Pathways of the Pulp Eighth Edition. St Louis: Mosby, 2002.

10. Hasselgren G. Chapter 9 in Ørstavik D and Pitt Ford TR. Essential Endodontology Oxford: Blackwell Science,1998.

11. Kakehashi S, Stanley H R, Fitzgerald R J. The effects ofsurgical exposures of dental pulps in germ-free andconventional laboratory rats. Oral Surgery, OralMedicine, Oral Pathology 1965; 20: 340�349.

12. Cvek M. A clinical report on partial pulpotomy andcapping with calcium hydroxide in permanent incisorswith complicated crown fracture. J Endod 1978; 4: 232�237.

13. Fuks A B, Chosack A, Klein H, Eidelman E. Partialpulpotomy as a treatment alternative for exposed pulpsin crown-fractured permanent incisors. Endod DentTraumatol 1987; 3: 10�102.

14. Torabinejad M, Hong C U, Lee S J, Monsef M, Pitt FordT R. Investigation of mineral trioxide aggregate forroot-end filling in dogs. J Endod 1995; 21: 603�608.

15. Schwartz R S, Mauger M, Clement D J, Walker W A.Mineral trioxide aggregate: a new material forendodontics. J Am Dent Assoc 1999; 130: 967�975.

16. Witherspoon D E, Ham K. One-visit apexification:technique for inducing root end barrier formation inapical closures. Practical Proceedings in AestheticDentistry 2001; 13: 455�460.

17. Cvek M. Treatment of non-vital permanent incisorswith calcium hydroxide IV. Periodontal healing andclosure of the root canal in the coronal fragment ofteeth with intra-alveolar fracture and vital apicalfragment. A follow-up. Odont Revy 1974; 25: 239�246.

18. Tronstad L. Root resorption � aetiology, terminologyand clinical manifestations. Endod Dent Traumatol1988; 4: 241�252.

19. Newman W G. Possible etiologic factors in externalroot resorption. Am J Orthod 1975; 67: 522�539.

20. Henry J L, Weinmann J P. The pattern of resorption andrepair of human cementum. J Am Dent Assoc 1951;42: 270�290.

12p735-743.qxd 19/11/2004 11:46 Page 742

PRACTICE


21. Andreasen J O. Textbook and Colour Atlas of TraumaticInjuries of the Teeth. Denmark: Munksgaard, 1993.

22. Cwyk F, Scat-Pierre F Tronstad L. Endodonticimplications of orthodontic tooth movement. J DentRes 1984; 63: Abstract 1039.

23. Gutmann J L. Prevalence, location and frequency ofaccessory canals in the furcation region of permanentmolars. J Periodontol 1978; 49: 21�26.

24. Seltzer S, Bender I B, Nazimor M, Sinai I. Pulpitis-induced inter-radicular periodontal changes in

experimental animals. J Periodontol 1967; 38: 124�129.25. Belk C E, Gutmann J L. Perspectives, controversies and

directives on pulpal-periodontal relationships. J CanDent Assoc 1990; 56: 1013�1017.

26. Solomon C, Chalfin H, Kellert M, Weseley P. Theendodontic-periodontal lesion: a rational approach totreatment. J Am Dent Assoc 1995; 126: 473�479.

27. Simon J H, Glick D H, Frank A L. The relationship ofendodontic-periodontic lesions. J Periodontol 1972;43: 202�208.

British Dental Journal, 15 September 1904

From a discussion of a paper read by Dr H.E. Knight to the NorthMidland Branch of the BDA in June 1904

Mr. Robbins wished to emphasise one point. For twenty-five years he had been tryingto find out why there should be such a dread of dentists; the fear being out of all pro-portion to the pain given. He had arrived at the conclusion that this was caused bywrong handling in early life. Therefore he was pleased that Dr. Knight recommendedthat a child should go to a dentist before it had learned fear. If given a child earlyenough, and a free hand to act squarely with that child, never taking it by surprise,that child should never be afraid of him as a dentist. If it were not afraid of him inchildhood, it would not be in after life.

Br Dent J 1904


12p735-743.qxd 19/11/2004 11:47 Page 743

shilpa

Rectangle

Endodontic treatment for childrenP. Carrotte1

Root canal treatment for children has particular difficulties and considerations. It must be planned in light of the remainingteeth, and the need for balancing or compensating extraction borne in mind. Diagnosis may be difficult, as may prolongedtreatment under local anaesthesia and rubber dam. Vital pulpotomy techniques with formocresol and/or calcium hydroxidemust be carefully executed in line with the UK National Guidelines. The treatment of the avulsed tooth has been the subject ofmuch research, and practitioners should ensure that they are up-to-date with current treatment modalities.


Refereed Paperdoi:10.1038/sj.bdj.4811946© British Dental Journal 2005; 198: 9–15

Root canal treatment in children should only be prescribed after careful consideration of thepatient, the existing dentition, and developing teeth.

Isolation with rubber dam is just as important as with the permanent dentition. Paediatric endodontic treatment may be more directed towards pulpotomy rather than

pulpectomy. All practitioners should be familiar with current guidelines on the treatment of the avulsed

tooth.

I N B R I E F

Although the basic aims of endodontic therapyin children are the same as those in adults, ie theremoval of infection and chronic inflammationand thus the relief of associated pain, there areparticular difficulties and considerations. Thepulpal tissue of primary teeth may becomeinvolved far earlier in the advancing cariouslesion than in permanent teeth. Exposure mayalso occur far more frequently during cavitypreparation due to the enamel and dentine beingthinner than in the permanent tooth, and thepulp chamber, with its extended pulp horns,being relatively larger, as can be seen in theextracted tooth at Figure 1. Primary molar rootcanals are irregular and ribbon-like in shape.Periradicular lesions associated with infectedprimary molars are usually inter-radicular

(Fig. 2) rather than periapical in site due to thepresence of accessory canals in the thin floor ofthe pulp chamber.

As well as the problems associated with theprimary dentition, endodontic treatment of permanent teeth in children may also presentdifficulties due to the incomplete root develop-ment and associated open apices.

BALANCED EXTRACTIONSPrimary teeth with pulpal exposure or pathologymust always be treated, either by root canal treat-ment or by extraction. The maintenance of archlength is important for good masticatory function and the future eruption of the permanent dentition with optimal developmentof the occlusion. Whilst it is preferable to











10. Endodontic treatmentfor children


Fig. 1 An extracted deciduous molar showing therelatively large pulp chamber and root canals.

Fig. 2 A radiograph of a grossly carious lower secondprimary molar showing interadicular bone loss.

PRACTICE

10VERIFIABLE CPD PAPER


BRITISH DENTAL JOURNAL VOLUME 198 NO. 1 JANUARY 8 2005 9

Endo_Chapter_10.qxd 10/12/2004 14:00 Page 9

conserve a tooth rather than carry out an extrac-tion, if this does become necessary, balancedextractions should always be kept in mind. Abalanced extraction is the removal of a toothfrom the opposite side of the same arch. A com-pensating extraction, removing a tooth from theopposing arch to the enforced extraction is moredifficult to justify.1 Balanced extractions arerarely justified for primary incisors. The loss of aprimary canine, however, may have a significanteffect on the arch and balanced extractionsshould always be considered. When a primarymolar has to be extracted it may be preferable toprevent drifting with a space maintainer thancarry out balanced extractions.

Extractions should be avoided wherever pos-sible in certain groups of children; ie those withbleeding disorders, or medical conditions suchas diabetes where general anaesthesia is contra-indicated. Primary teeth should also be retainedwhere a radiograph reveals the lack of a perma-nent successor, as in Figure 3, where the patientmay find pulp therapy less stressful than extrac-tion, and in an already crowded dentition wheretooth loss would lead to even further crowdingof the permanent teeth.

ENDODONTIC TREATMENT OF PRIMARYTEETHEndodontic treatment may be indicated far earli-er when treating the primary dentition than inpermanent teeth. Obviously, treatment is indicat-ed when a patient presents with a pulpal necrosis,or symptoms of pulpitis. However, the distinctionof reversible or irreversible pulpitis applied to thepermanent teeth is not so relevant in the primaryteeth; any sign or symptom of pulpitis indicatesthe need for pulp therapy. Current research andpractice also suggests that pulp therapy will benecessary when a radiograph shows a cariouslesion extending more than halfway through thedentine, or where the carious process has led tothe loss of the marginal ridge.

However, there are important assessments tobe made as to the patient’s suitability forendodontic treatment. The general health of thepatient should be checked to ensure that thereare no contra-indications to endodontic therapy,

such as those with congenital heart disease, orpatients who are immunocompromised. The atti-tude of the parent to treatment and the child’sability to cooperate during the more lengthyprocedures require careful evaluation. The over-all dental health of the child, with particular ref-erence to the caries experience, must be takeninto account when making a treatment plan. In apoorly cared for dentition requiring multipletreatments, the complex conservation of onetooth in the presence of a number of comparableteeth of doubtful prognosis is poor paediatricdentistry and should be avoided. In addition,root canal treatment should be avoided in gross-ly decayed teeth which may be unrestorableeven after pulp therapy; in teeth where caries haspenetrated the floor of the pulp chamber; inteeth with advanced root resorption, or thoseclose to exfoliation.

An additional problem is the close relation-ship of the roots of the primary teeth to thedeveloping permanent successor. During exfoli-ation, the roots of the former resorb, necessitat-ing the use of a resorbable paste in endodontictreatment. It is also important to remember thattrauma to, or infection of, a primary tooth, mayresult in damage to the permanent tooth. Thismay vary from enamel hypomineralisation andhypoplasia to, more rarely, the delayed orarrested development of the tooth germ (Fig. 4).

DiagnosisThe reaction of pulp tissue in primary teeth todeep caries differs from that seen in the perma-nent dentition and is characterised by the rapidspread of inflammatory changes throughout thecoronal portion of the tooth. These pathologicalchanges become irreversible and, if left untreat-ed, will involve the radicular tissue. There maybe few, if any, clinical symptoms in the earlystages to indicate the extent of tissue damage.Pain may only occur after involvement of theperiradicular tissues in the spread of infection.

Children are often unable to give accuratedetails of their symptoms, and the responses toclinical tests may be unreliable. Difficulties arefrequently experienced in ascertaining thecondition of the pulp from clinical findings.

PRACTICE

Fig. 3 A dentalpanoramic tomographtaken as part of theassessment forextraction of deciduousmolars, reveals theabsence of permanentlower second premolars.

Fig. 4 Enamel hypoplasia of an upper permanent incisorfollowing infection of the primary predecessor.

10 BRITISH DENTAL JOURNAL VOLUME 198 NO. 1 JANUARY 8 2005


Radiographs, which are essential prior to thecommencement of treatment, may give littleinformation of early pathological changes.

Before commencing treatmentThe majority of the following restorative proce-dures will require adequate local anaesthesia. In accordance with the biological principlesestablished throughout this text, adequate isola-tion will also be necessary to prevent salivarycontamination. A rubber dam should be placed,and isolation completed with cotton wool rollsand saliva ejector as seen in Figure 5.

Indirect pulp cappingThe aim of this treatment is to maintain thevitality of the pulp in a deep carious lesion,when there is no direct pulpal involvement. Allthe carious dentine must be removed, and a thinlayer of sound, non-carious dentine mustremain. A lining of setting calcium hydroxide is placed, which stimulates the formation ofsecondary dentine. The tooth is restored overthe dressing with a permanent restorativematerial.

It has been suggested that other medicamentsmay be used for indirect pulp caps, for exampleantibiotic pastes and anti-inflammatory drugs,but although some success has been reported,pulp necrosis and abscess formation often resultwithout symptoms. As with the permanent den-tition, research is presently focussing on the useof adhesive materials and bonding agents forindirect pulp capping. The long-term results ofthese long-term clinical trials are awaited.

It should be noted that one technique for indi-rect pulp capping, which was described in thepast, is no longer recommended. This was wheredeep caries was carefully excavated, avoidingpulpal exposure, and the deeper layers of soft-ened dentine dressed with a calcium hydroxide-containing cement and a long-term temporarydressing. After a period of 6–8 weeks the tooth,which should have been symptomless, wasreopened, and the arrested carious lesion exam-ined. The success of this treatment was found tobe less predictable and symptoms frequentlydeveloped. It is now recommended that all cariesbe removed, and if a pulpal exposure is foundthen either a direct pulp cap or a form of pulpo-tomy is used.

Direct pulp cappingThis treatment is only recommended when asmall traumatic exposure occurs, during cavitypreparation of a vital non-infected pulp.2 A cal-cium hydroxide dressing is placed directly overthe pulp, followed by a lining and restoration,and the whole technique is carried out usinglocal anaesthesia and with adequate isolationfrom salivary contamination. It has been sug-gested that the high cellular content of primarypulp tissue may be responsible for the failure ofdirect pulp capping in primary teeth.3 Undiffer-entiated mesenchymal cells may differentiateinto osteoclastic cells in response to either thecaries or direct pulp capping which leads to inter-nal resorption. It is also suggested that exposureson axial walls have a poor prognosis as the pulpcoronal to the exposure may be deprived of itsblood supply and undergo necrosis.

Vital pulpotomy techniquesThese techniques involve the removal ofinflamed coronal pulp tissue and the applicationof a dressing to the radicular pulp in an attemptto either promote healing of, or fix, the upperportions, and to preserve the vitality of the apicaltissue. Because of the difficulties involved indiagnosing the condition of the pulp tissue histo-logically before the commencement of treatment,careful assessment must be made at each stage ofthe procedure. Whenever the haemorrhage fromthe radicular pulp stumps is profuse and uncon-trolled, the assumption is made that the inflam-matory process has extended into the radiculartissue, and the therapy modified accordingly.There are three pulpotomy techniques.

Vital formocresol pulpotomyThe treatment is carried out using local anaesthe-sia and adequate isolation. Following cavitypreparation in the normal manner, the deep cariesis removed and the coronal pulp chamber opened,such that there is no overhanging dentine inhibit-ing the complete removal of the pulp tissue. Thecoronal tissue is removed using a large excavatoror sterile rosehead bur. If a high-speed diamondbur is used it should be cooled with sterile wateror saline. Sterile cotton wool is applied to theradicular pulp tissue to achieve haemostasis. Asmall pledget of cotton wool is dipped in a 1:5dilution of Buckley’s formocresol (Table 1) and

PRACTICE

Fig, 5 A deciduous molar with a deepcarious lesion has been isolated priorto commencing endodontic therapy.



squeezed to remove excess liquid. It is placed overthe radicular pulp stump for 5 minutes in order tofix the inflamed tissue and bacteria and thusallow healing of the unaffected pulp. If the haem-orrhage has completely stopped, a layer of zincoxide–eugenol or glass-ionomer cement isapplied, and the tooth restored, preferably with apreformed stainless steel crown to prevent subse-quent fracture of the weakened tooth (Fig. 6).

Other materials have been considered as analternative to formocresol.4 Concerns about thesafety of formocresol led to investigations ofpulpotomies employing a 2% glutaraldehydesolution as an alternative dressing, but researchhas shown a lower clinical success rate than withformocresol. Concern about hypersensitivity toand handling of glutaraldehyde have largely ledto its abandonment as a treatment alternative.

Recent work by Waterhouse et al. has shownthat very favourable results have been achievedwith calcium hydroxide when it has beenapplied in carefully controlled circumstances.5

Following haemostasis, calcium hydroxide pow-der was delivered to the pulp chamber using asmall, sterile, endodontic amalgam carrier. Thepowder is condensed over the pulp stumps withan amalgam condensor and small pledgets ofcotton wool. Failure of this technique isexplained by the presence of an extra-pulpalclot separating the calcium hydroxide from thepulpal tissue and thus impairing healing.3

Both the calcium content and alkaline proper-ties of the dressing are important to achievehealing. An initial layer of necrotic tissue devel-ops, which becomes associated with an inflam-matory reaction. Subsequently, a matrix formsand mineralises to become a hard tissue barrierof dentine-like material.

Devitalisation pulpotomyThis is a two-stage procedure, used when localanaesthesia cannot be obtained to permit extir-pation of the pulp, or when haemorrhage isuncontrolled before or following the applicationof formocresol. This technique mummifies andfixes the coronal pulp tissue, whilst the majorpart of the radicular pulp remains vital, but itcarries a lower success rate.6

If the tooth is not anaesthetised, cavity prepa-ration is carried out as far as possible and accessis gained to the pulpal exposure. A small amountof paraformaldehyde devitalising paste (Table 2)on a pledget of cotton wool is applied to theexposed pulp tissue. Formaldehyde vapour liber-ated from the dressing permeates through thepulpal space, producing fixation of the tissues. Asoft layer of zinc oxide–eugenol temporarydressing is then placed, without applying pres-sure, to seal the medicament in position. Thechild and parent must be warned of possible dis-comfort, for which analgesics are recommended.After one to two weeks the tooth is checked forsigns and symptoms. The devitalised coronalpulp may now be removed, without the need forlocal anaesthesia. A hard setting layer of zincoxide–eugenol, which may be mixed withformocresol, is then placed over the radicularstumps and the tooth restored. If some vital tissueremains in the coronal pulp chamber, a furtherdressing of paraformaldehyde paste is required.

Non-vital pulpotomyThis technique has been advocated where there isirreversible change in the radicular pulp, or wherethe pulp is completely non-vital, but wherepulpectomy and root canal treatment is consid-ered impractical. The little clinical evidence

PRACTICE

Fig. 6 Stainless steelcrowns make idealrestorations forcompromiseddeciduous molars.

Table 1 Buckley’s formocresol

Tricresol 35%

Formaldehyde 19%

Glycerol 15%

Water 31%

Table 2 Paraformaldehyde devitalising paste

Paraformaldehyde 1.00 g

Carbowax 1500 1.30 g

Lignocaine 0.06 g

Propylene glycol 0.5 ml

Carmine 10 mg



PRACTICE

available suggests a limited prognosis of approxi-mately 50%. At the first visit the necrotic pulpcontents are removed as before, and, using smallexcavators, as much as possible of the radiculartissue. Beechwood creosote solution (Table 3) on acotton pledget is sealed into the cavity with a zincoxide–eugenol dressing.

One to two weeks later the tooth is checked forsigns and symptoms. If there is evidence ofinfection (sinus, pain, swelling or mobility) afurther beechwood creosote dressing should beplaced. If, however, symptoms have resolved, thetooth may be restored as with the previouspulpotomy techniques.

PulpectomyPulpectomy is indicated where the pulp is eithernon-vital or irreversibly inflamed. Although thetechnique is often considered difficult becauseof the complexity of the root canals in primarymolars, clinical studies have shown a reasonableprognosis.7 The cavity preparation and removalof the necrotic coronal pulp is carried out as pre-viously described. If the radicular pulp is necrot-ic, a two-stage procedure is required, but if it isfound to be irreversibly inflamed a one-stagetechnique may be undertaken.

One-stage techniqueThe root canals are identified and instrumented tothe working length estimated from a pre-operativeradiograph. After drying the canals with paperpoints, formocresol is applied for up to 5 minutes.The root canals are then filled with a thin mix ofzinc oxide–eugenol, using a rotary paste filler, andthe restoration of the tooth is completed.

Two-stage techniqueHere the root canals are again cleaned, shapedand irrigated to remove all necrotic debris. Apledget of cotton wool moistened with eitherformocresol or beechwood creosote is sealed inthe pulp chamber with a rigid zinc oxide–eugenol dressing for one week. At the subsequentvisit the tooth should be symptom-free, firm,without a discharging sinus. (If not, a secondapplication of beechwood creosote is required.) Ifthe tooth is found to be symptomless, a dressingof zinc oxide–eugenol, with or without the addi-tion of formocresol, is packed into the base of thechamber and the tooth finally restored.

The preceding techniques are reviewed in theUK National Guidelines.8

ReviewFollowing any form of endodontic treatment,regular clinical and radiographic reviews mustbe made of the tooth involved and its successor.If rarefaction of the bone in the furcation area isseen, further pulpectomy may be possible, butextraction is probably indicated. Radiographsshould also be checked for evidence of internalresorption, which may occur in limited areas informocresol pulpotomies, but may be moreextensive following the use of calcium hydrox-ide. It may progress to cause perforation of the

root. Inflammatory follicular cysts9 may devel-op, which necessitate the removal of the primarytooth and marsupialisation of the cyst to allowthe permanent tooth to erupt.

PERMANENT DENTITIONImmature permanent incisorsAlthough one in five children will suffer traumato their developing permanent incisors, onlyabout 6% of these will subsequently becomenon-vital and require endodontic treatment. Thecorrect initial diagnosis of such traumatisedteeth, based on signs and symptoms, radi-ographic examination and sensibility testing, istherefore very important. Laser Doppler flowme-try has shown that traumatised immature teethwith open apices may have a vital pulp even inthe absence of a response to conventional sensi-bility testing. If there is any uncertainty aboutthe vitality of the pulp, root canal treatmentshould be deferred and the tooth kept underregular review.

If, however, endodontic treatment of animmature permanent tooth with an open apex isindicated, a root-end closure technique is neces-sary to form a calcific barrier against which theobturation may eventually be compacted with-out extruding material into the periradiculartissues (Fig. 7).

The tooth should be isolated with rubber dam,and the pulp chamber accessed. Local anaesthe-sia is usually given as some vital tissue may stillbe encountered during pulp extirpation. Insevere cases an intracanal steroid dressing, suchas Ledermix, may be required for one week.Canal preparation is carried out with files toapproximately 1–2 mm short of the workinglength, estimated from the pre-operative radi-ograph and confirmed during treatment. Copi-ous irrigation with a sodium hypochlorite solu-tion is necessary to remove all necrotic debris.The root canal should be dried with paper points,and then filled to the apex with calcium hydrox-ide paste, compressed with large paper pointsand/or cotton pledgets. The access cavity shouldbe sealed with a long-term temporary dressing,such as glass-ionomer cement.

After one month, the dressing is carefullyremoved with copious irrigation, and the driedcanal refilled with calcium hydroxide paste.After a further three to six months the tooth isopened again and a large paper point used atworking length to feel for a calcific barrier. Thepaper point is gently inserted into the clean, drycanal. At the estimated working length either thepoint will remain dry, tap against a hard barrier,

Table 3 Beechwood creosote

0-Methoxy phenol (Guaicol) 47%

P-Methoxy phenol 26%

2-Methoxy, 4 methyl phenol (Cresol) 13%

M-Methoxy phenol 7%

Other 7%



PRACTICE

with no sensation to the patient indicating clo-sure, or will press against soft granulation tissuewhich the patient will feel. The average timetaken for closure is 6 months.

If no barrier is detected, the calcium hydroxideis replaced. If the open apex is found to be completely closed, the canal may be obturatedwith gutta-percha and sealer. Closure of an openapex may be anticipated in over 90% of casestreated by this technique, with a 4-year progno-sis of 85%.10 Obturation may then be completedby one of several methods. Conventional coldlateral compaction may be used, perhaps invert-ing a large gutta-percha point to obtain a goodapical tug-back. A custom gutta-percha pointmay be made by rolling several GP pointstogether after softening in solvent or gentleheat, and repeated fitting to the canal, carefullymarking the orientation at insertion. However,injectable thermo-plasticised gutta-percha maybe the most suitable obturation medium.

First permanent molarThe first permanent molar may, soon after erup-tion, show extensive caries, sometimes associat-ed with hypoplasia. Consideration must be givento the age of the patient and the dental develop-ment, the occlusion and possible need for ortho-dontic treatment, as well as the long-termrestorative prognosis of the tooth and thepatient’s ability to tolerate involved treatmentover a long period. Where necessary, plannedextractions should be considered. The primaryaim of conservation is to ensure that root growthcontinues with completion of apical formation,so that definitive endodontic treatment, ifrequired, may be carried out at a later stage.

The vitality of the tooth must be assessed andradiographs should be available, showing theextent of carious involvement and the state ofthe periapical tissues. It is essential that a localanaesthetic is administered and salivary control

achieved by adequate isolation. Caries should beexcavated and the tooth treated in accordancewith conventional protocols. If a small exposureof a vital tooth occurs, either accidentally duringcavity preparation or because of caries, and thesurrounding tissue is healthy, a direct pulp capwith calcium hydroxide cement may be applied.A lining of glass-ionomer cement is then placedto seal the dentine tubules prior to the definitiverestoration. If amalgam is used, a dentine bond-ing system should be considered to ensure complete sealing of the restoration.

If the exposure is large and the vitality of theradicular pulp is to be maintained to allow forroot development, a pulpotomy may be carriedout. Following the opening of the coronal pulpchamber and the removal of the pulp tissue, thearea is irrigated and dried. Haemostasis of theradicular pulp should be observed prior to theapplication of calcium hydroxide cement orpaste, and the provision of a permanent restora-tion. A calcific barrier should develop adjacentto the dressing, and root development continuein the presence of healthy pulp tissue.

If the pulp of a young, permanent molar isfound to be non-vital, endodontic treatmentshould be undertaken only after careful assess-ment of the developing occlusion, the conditionof the comparable teeth, the patient’s ability tocooperate and the long-term prognosis of thetooth. If pulpal necrosis occurs prior to the com-plete development of the apex, the objective oftreatment, as described earlier, is to encouragefurther deposition of calcified tissue in the apicalregion. Thorough preparation of the root canalsis carried out, avoiding damage to the apical tis-sues and cells of Hertwig’s root sheath. Calciumhydroxide is then applied as previouslydescribed. Definitive endodontic treatment iscarried out when an apical barrier has formedand the tooth is then permanently restored. Ifsymptoms arise in fully developed, young,

Fig. 7 a) An immature tooth with anon-vital pulp has been filled withcalcium hydroxide b).

a b



PRACTICE

permanent teeth, conventional orthograde root-filling with gutta-percha and sealer is indicated.

Avulsed permanent teethIn the emergency management of an avulsedpermanent tooth, time is of the essence. Thelong-term prognosis begins to deteriorate afteronly 15 minutes.11 Most cases initially presentwith a telephone call. Where possible, re-implantation should be immediate, followingrinsing if necessary in either milk (preferably) ortap water. The tooth should be held in place bybiting gently on a soft cloth until splinting ispossible by the dentist. If the person attendingthe accident is not prepared to re-implant thetooth, it should be stored in milk, normal salineor saliva (in the buccal sulcus) during the journeyto the dental surgery.

Avoiding unnecessary delay, and keeping thetooth in the transport solution to prevent dryingof the periodontal fibres, a thorough medical,dental and accident history should be taken andrecorded. Local anaesthesia may be necessary topermit manipulation of the alveolar bone, and toenable gentle syringing of the socket with salineto remove any blood clot. The tooth, handledonly by the crown, should be carefully insertedinto the socket. Root canal treatment should NOTbe commenced before re-implantation.

A non-rigid splint should be applied for 7–10days, using acid-etched resin with a soft archwire. The patient should be advised to avoid bit-ing on the splinted tooth, take a soft diet, andmaintain good oral hygiene with careful brush-ing and a chlorhexidine mouth-rinse. Systemicantibiotics may be indicated for medically com-promised patients. The patient’s tetanus statusmust be checked and a booster given by a med-ical practitioner if necessary. A review appoint-ment should be made in two days to verify thesplint, and modify it if necessary.

In very young patients where the tooth has awide-open apex and was out of the mouth foronly a short period there is a possibility of re-vascularisation of the pulp. The tooth should bekept under almost weekly review, and if anyclinical signs of non-vitality develop, such astenderness, discoloration, swelling or sinus for-mation, endodontic treatment should be com-menced immediately. Endodontic treatmentshould be commenced on all other avulsed teethwhilst the splint is in place. A long-term calciumhydroxide dressing should be sealed in place

with a glass-ionomer restoration for at least 6 months prior to verification of an apical barrierand obturation as described earlier.

Replanted teeth should be regularly reviewedfor at least 2–3 years, checking for inflammatoryresorption, replacement resorption, ankylosis,infra-occlusion and discoloration. The adjacentteeth should also be reviewed. Resorption maycommence within weeks of the injury.

Finally, it should be realised that there are somesituations where replantation is not appropriate.For example:• If the patient has other serious injuries,

which should be given priority. • If the patient has an at-risk medical history.• Where the extra-oral time is very prolonged,

the prognosis is very poor, particularly inteeth with short roots and wide apices.

• Primary teeth should not be replanted due tothe possibility of damage to the permanentreplacement.

Figures 1, 2, 3, 5, 6 and 7 have been reproduced by kindpermission of Dr M-T Hosey, Children’s Department,Glasgow University. Figure 4 is reproduced by kind permission of Professor R RWelbury.

1. BSPD and IAPD. UK national guidelines in paediatricdentistry. Int J Paediatr Dent 2002; 12: 151–153.

2. Kopel H M. Considerations for the direct pulp cappingprocedure in primary teeth: A review of the literature.Paediatr Dent 1992; 59: 141–149.

3. Gould A, Johnstone S, Smith P. Pulp Therapytechniques for the deciduous dentition. (CompactDisk) London: King’s College, 1999.

4. Waterhouse P J. Formocresol and alternative primarymolar pulpotomy medicaments: a review. Endod DentTraumatol 1991; 11: 157–162.

5. Waterhouse P J, Nunn J H, Whitworth J M. Aninvestigation of the relative efficacy of Buckley’sFormocresol and Calcium Hydroxide in primarymolar vital pulp therapy. Br Dent J 2000; 188: 32–36.

6. Coll J A, Sadrian R. Predicting pulpotomy successand its relationship to exfoliation and succedanesusdentition. Paediatr Dent 1996; 18: 57–63.

7. Barr E S, Flaitz C M, Hicks M J. A retrospectiveradiographic evaluation of primary molarpulpectomies. Paediatr Dent 2000; 13: 4–9.

8. Llewelyn D R. UK national guidelines in paediatricdentistry. Int J Paediatr Dent 2000; 10: 248–252.

9. Shaw W, Smith D M, Hill F J. Inflammatory follicularcysts. J Dent Child 1980; 47: 97–101.

10. Mackie I C, Worthington H V, Hill F J. A follow upstudy of incisor teeth which have been treated byapical closure and root filling. Br Dent J 1993; 175:99–101.

11. Andersson L, Bodin I. Avulsed human teeth replantedwithin 15 minutes — a long term clinical follow-upstudy. Endod Dent Traumatol 1990; 6: 37–42.



PRACTICE

Surgical endodontics

Root canal treatment usually fails because infection remains within the root canal. An orthograde attempt at re-treatmentshould always be considered first. However, when surgery is indicated, modern microtechniques coupled with surgicalmagnification will lead to a better prognosis. Careful management of the hard and soft tissues is essential, specially designedultrasonic tips should be used for root end preparation which should ideally be sealed with MTA. All cases should be followedup until healing is seen, or failure accepted, and should form a part of clinical audit.

A surgical approach to a failed root canal treatment should only be considered when anorthograde approach is not possible.

The reason for failure should be carefully diagnosed before surgery is prescribed. Modern periradicular surgery involves the use of an operating microscope, microsurgical

instruments, and appropriate retrograde sealing materials All surgical treatment should be followed-up, and encompassed in audit procedures.

I N B R I E F

Although conventional orthograde root canaltherapy must always be the preferred method oftreating the diseased pulp, there are occasionswhen a surgical approach may be necessary. Iforthograde treatment has failed to resolve thesituation, the clinician should make every effortto ascertain why this has happened. A surgicalapproach is only indicated when it is agreed thatorthograde retreatment is either not possible orwill not solve the problem.

The two cases shown in Figures 1 and 2, bothof which were referred for periradicular surgery,illustrate this point well. Figure 1 shows a radi-ograph of a lower molar that was causing symp-toms, having first been obturated with silver

points and subsequently suffered surgery whenthe problem did not resolve. The correct treat-ment should have been a repeat of the orthogradetreatment to remove the infection from withinthe root canal space that was causing the failure.Figure 2 shows totally inadequate endodontictreatment. The case requires total dismantlingand thorough orthograde retreatment.

There have been considerable developments inperiradicular surgery, both in technique andmaterials, in recent years.1–6 Specialist practition-ers routinely use surgical microscopes in conjunc-tion with specially designed microsurgical instru-ments and retrograde filling materials. Adescription of these techniques is included in thischapter, and general practitioners are encouragedto compare this with their current practice, andadopt as many of these new procedures as

11













Fig. 1 This tooth has been obturated with silver points,and subsequently received periradicular surgery. Thecorrect treatment should have been orthograderetreatment and conventional obturation

Fig. 2 This case requires complete dismantling andorthograde retreatments. Periradicular surgery is unlikelyto be successful

1*Clinical Lecturer, Department of AdultDental Care, Glasgow Dental Hospital andSchool, 378 Sauchiehall Street, GlasgowG2 3JZ*Correspondence to: Peter CarrotteEmail: [email protected]





2p71-79.QXD 10/01/2005 11:30 Page 71

possible. Alternatively, if these new techniquesare not employed, greater consideration should be given to referral for specialist surgicaltreatment.

INDICATIONS FOR SURGICAL INTERVENTIONAlthough endodontic surgery is carried out primarily in cases of failed orthograde treatment,there are other indications. Surgery may be necessary to establish drainage, (considered in Part 3); to biopsy a lesion; to repair any defects or perforations in the tooth root; to resecta multi-rooted tooth where, for technical reasons,one of the roots cannot be successfully treated.

Biopsy of a periapical lesionThe one specific indication for endodontic surgery is uncertainty about the nature of theapical lesion. The lesion should be excised in itsentirety and sent for evaluation.

Root-end resection (apicectomy)The term apicectomy refers to a stage of theoperation only. The principal objective is to sealthe canal system at the apical foramen from theperiradicular tissues. To do this it is necessaryto resect the apical part of the root to gainaccess to the root canal, hence the term. Root-end resection must be an adjunct measure toorthograde root treatment for two reasons.Firstly, there is very little chance of being ableto seal all the lateral communications betweenthe canal and the periodontal ligament with aretrograde root-filling technique. Secondly, thearea of root-filling material exposed will begreater and the long-term success affected,because all root-filling materials are, to someextent, irritant to the tissues.

Indications for root-end resectionImprovements in root canal treatment tech-niques have lessened the need for apicalsurgery. Cases which at first seem obvious candidates for endodontic surgery may respond to conventional treatment provided carefulthought is given to the aetiology. Once the decision has been made to carry out surgery, consideration must be given to thechances of success (see Part 12). Access andcontrol of the operating environment are essential, otherwise the end result will be counterproductive.

Retreatment of a failed root fillingSurgery may be considered if a root filling failsand retreatment cannot be effected by orthogrademeans. There are a number of reasons why a rootfilling might fail, but generally this is due to inadequate cleansing and filling of the root canal.Some root fillings can prove very difficult toremove, for example hard setting pastes. Occasionally there may be an anatomical reasonfor the failure, such as an unfilled apical delta. Attempts at retreatment by a conventionalorthograde route may be unsuccessful because the original canal cannot be negotiated. Periradic-ular surgery and root-end filling is therefore

PRACTICE

Fig. 3 The only waythat this extrudedfilling material maybe removed is by asurgical approach

Fig. 4 It would almost certainly be impossible to carry outorthograde root canal treatment on this tooth

Fig. 5 The pulpal space in this tooth hasbeen obliterated following trauma.Orthograde access proved impossible


2p71-79.QXD 10/01/2005 11:31 Page 72

Fig. 9 These lower incisors have been treated butsymptoms have persisted at tooth 41 (LR1). Theradiograph shows that the periodontitis is centred on theportal of exit from a lateral canal, which still mustcontain infected debris

Fig. 8 It was agreed that any attempt to remove the largepost and core in tooth 21 (UL1) to permit orthograderetreatment may result in a root fracture. The patientelected for a surgical approach

justified to ensure that the apical foramen hasbeen sealed.

Root-filling material which has been extrudedthrough the apical foramen may be a contribu-tory cause of failure, since it could be an indica-tion that the apical seal is deficient; necroticmaterial may be present at the apex and betweenthe interface of the root filling and the canalwall; the root-filling material itself may be highly irritant (Fig. 3).

PROCEDURAL DIFFICULTIESDuring conventional orthograde root canaltreatment, problems may arise as a result of oneof the following:• Unusual root canal configurations (Fig. 4).• Extensive secondary dentine deposition

(Fig. 5).• Fractured instruments within the root canal

(Fig. 6).• Open apex (Fig. 7).

• Existing post in the root canal unfavourablefor dismantling (Fig. 8).

• Lateral or accessory canal (Fig. 9).

Unusual root canal configurationsInstrumentation of canals in roots which exhibitbizarre morphology or severe dilaceration mayprove impossible. Similarly, where there is anapical delta, thorough cleansing, shaping andobturation of the canal may prove impossibleand surgery will be required to complement theorthograde approach.

PRACTICE

Fig. 7 Orthograde attempts havefailed to obturate this tooth with anopen apex

Fig. 6 This fractured instrument in the apical third of theroot canal proved impossible to remove


2p71-79.QXD 10/01/2005 11:32 Page 73

Extensive secondary dentine depositionThe ageing process results in the deposition ofsecondary dentine, with a consequent reductionin size of the pulp chamber and the root canal.Even more profound sclerosis may result in atooth which has been subjected to trauma. Anasymptomatic irreversible pulpitis may result,bringing about sclerosis of the root canal sys-tem. The canals may then be almost completelyobliterated and it may prove impossible to iden-tify the canals with even the smallest instru-ments. Under these circumstances, continuedsearching deep in the root may result in exces-sive damage, weakening of the root, or even per-foration. Periradicular surgery is then the onlyalternative to extraction.

Fractured instruments within the root canalInstruments which have fractured in a root canaldo not necessarily result in failure of the roottreatment. They should be removed if possible,but if this is impossible, then an attempt shouldbe made to seal the rest of the canal with theinstrument in place. Surgery is only necessary ifthe tooth develops symptoms, or radiographicreview shows a failure of healing. The incidentshould, of course, be recorded in the records, andthe patient informed.

Open apexTeeth that have been injured before root develop-ment is complete should be treated conventionallyin the first instance. If the pulp is vital, then thecoronal pulp is removed and the remaining vitalradicular pulp is covered with calcium hydroxideto allow continued root development; this istermed ‘apexogenesis’. If the pulp is irreversiblyinflamed, then the radicular pulp is removed andthe canal filled with calcium hydroxide toencourage root formation and closure of theapex; this is termed ‘apexification’.7

However, should the treatment fail, then api-cal surgery may be necessary, to provide an api-cal seal after completion of the orthograde rootfilling. Care must be exercised when carryingout this operation as the root structure is oftenvery delicate.

Existing post in the root canalPeriradicular surgery may be indicated forteeth with symptomatic periapical lesionswhich have satisfactory post crowns in place,provided the root filling in the main body ofthe canal is satisfactory. However, it has to beremembered that success depends on the canalsystem being completely sealed. If there is anydoubt about this, it is better to remove thecrown and post and carry out orthograde roottreatment, avoid surgery, and thus provide asound foundation for any subsequent restora-tion. Dismantling of post crowns is, however,not always straightforward. An assessmentmust be made of the length and shape of thepost, the strength of the remaining root struc-ture and, if possible, the cement used. Injudi-cious force during post removal may lead toroot fracture and the loss of the tooth. The situ-ation should be discussed in detail with thepatient in order that informed consent to thechosen procedure is obtained.8

Lateral or accessory canalModern endodontic techniques should enable theroot canal to be shaped adequately to permitflushing of sodium hypochlorite irrigationthroughout the entire root canal system. Unfortunately, infected debris may occasionallypersist in lateral or accessory canals. Whilstorthograde retreatment may be attempted, a surgical approach may be the only solution, par-ticularly if these canals form part of the apicaldelta which may be eliminated by adequate surgical resection.

SURGICAL REPAIR OF ROOTSSurgery may be necessary to repair defects in aroot surface due to either iatrogenic or patho-logical causes. The two main indications are asfollows.

PerforationsWhere possible, an orthograde approach shouldfirst be used to seal the perforation, ideally usingmineral trioxide aggregate (MTA). If this is notpractical, the canal must be thoroughly cleanedand filled with calcium hydroxide paste to dry itout and to allow the tissues time to heal. The pre-pared canal space should then be obturatedusing conventional root canal filling techniques.Perforations caused by instrumentation errorscan usually be treated by an orthogradeapproach as the access is generally good. How-ever, if clinical symptoms persist or there is boneresorption, or in the case of a large perforationas shown in Figure 10, a surgical approach willbe necessary.

Internal and external root resorptionInternal resorption should always be treated byan orthograde route first. If the resorptive processhas perforated through to the periodontal liga-ment, then surgery may be necessary to repair theroot and provide an effective seal. Certain types ofexternal root resorption in the early stages can be

PRACTICE

Fig. 10 If this tooth isto be retained with thispost perforation,surgical repair will berequired


2p71-79.QXD 10/01/2005 11:33 Page 74

PRACTICE

dealt with by surgery, provided access can begained to the area (see root resorption).

Root amputation and hemisectionPeriradicular surgery on a posterior tooth is amore difficult procedure to carry out than on ananterior tooth. For this reason, the relatively sim-pler techniques of root amputation or hemisec-tion may be considered. The changes in endodon-tic and periodontal treatment techniques in recentyears have greatly improved the prognosis forthis form of treatment. The principal indicationsare endodontic, restorative or periodontal. Rootamputation is an operation where one entire rootof a multirooted tooth is removed, leaving thecrown intact. Hemisection is the division of atooth, usually in a buccolingual plane. Normally,one half of the tooth is removed, but both sectionsmay be retained if there is disease in the furcationarea only. However, the restorative problems thistype of treatment poses are considerable and forthis reason the prognosis is generally poor. Pre-operative assessment of both the periodontal andrestorative aspects is crucial if these methods oftreatment are contemplated.

MEDICAL AND DENTAL CONSIDERATIONSAlthough there are few absolute contra-indica-tions to endodontic surgery, a well-documentedmedical history is essential (see Part 2). In gen-eral, heart disease, diabetes, blood dyscrasias,debilitating illnesses and steroid therapy maycontra-indicate surgery and special measuresare necessary if surgery is contemplated. Con-sideration must also be given to psychologicalfactors. As a rule, local analgesia is preferable,but patients who are particularly apprehensivemay wish to have any surgery carried out undersedation. The choice of anaesthetic may also begoverned by the nature of the operation, the siteof the tooth and ease of access. A history ofrheumatic fever is not a contra-indication forendodontic surgery, provided appropriateantibiotic cover is given. If there is any doubtabout a patient’s fitness to undergo any surgicalendodontic procedure, then the patient’s physi-cian should always be consulted.

The first considerations are whether the toothis worth saving and how important it is in theoverall treatment plan. The general state of themouth should be considered, both hard and softtissues. The quality of restorative work in thetooth concerned should be particularly noted,and an assessment must also be made of theeffects of any proposed surgery on the periodon-tal condition. The presence of any detectabledehiscence or bony fenestration will influencethe design and extent of the flap.

A periapical radiograph should provide all theinformation required for assessment of thetooth, although it may be necessary to exposemore than one film, from different angles. Atleast 3 mm of the periradicular tissues should beclearly visible. Assessment should be made ofthe root shape, taking into account any unusualcurvature and the number of foramina that may

be exposed at the apex as a consequence of theoperation. If a sinus is present in the soft tissues,the sinus tract should be visualised by taking aradiograph with a gutta-percha point threadedinto the tract, as shown in Part 2, Figure 5.

Good visual access is extremely important,and the anatomy of the area must be thoroughlyunderstood. The position of any major structuressuch as neurovascular bundles and the maxil-lary sinus must be noted. A buccal or labialapproach is always preferred, as a palatalapproach is difficult and should only be under-taken in exceptional circumstances by experi-enced practitioners.

One of the key factors influencing the successor failure or periradicular surgery is the experi-ence and expertise of the operator. Considera-tion should always be given to referral to anappropriate specialist, especially in difficultcases. A letter of referral should include a fullclinical and medical history, and all relevantradiographs. Both the referring dentist and thespecialist providing treatment have a responsi-bility to obtain informed consent to the procedure.

PERIRADICULAR SURGERY TECHNIQUEThe steps for carrying out this procedure are:1. Pre-operative care.2. Anaesthesia and haemostasis.3. Soft-tissue management.4. Hard-tissue management.5. Curettage of area.6. Resection of root.7. Retrograde cavity preparation.8. Retrograde filling.9. Replacement of flap and suturing.10. Post-operative care.

Pre-operative careAlthough prophylactic antibiotic therapy is notusually required for routine periradicular sur-gery, systemic antibiotics may be required forany flare-ups prior to surgery. Chlorhexidinemouthwashes may also be beneficial, and these,together with systemic non-steroidal anti-inflammatory drugs, should be considered fromthe day prior to surgery.9

Anaesthesia and haemostasisWherever possible, local anaesthesia is themethod of choice, although anxious patientswho cannot be controlled with tranquillizersmay also require intravenous sedation. The local anaesthesia injection also provideshaemostasis, essential for good endodontic surgery. Following topical anaesthetic applica-tion, an anaesthetic solution with at least1:80,000 adrenaline is injected slowly into sev-eral sites surrounding the surgical field. Localanaesthetic solutions containing Octapressin donot give adequate haemostasis and should beavoided if possible.

In the mandible, block injections should begiven, in addition to infiltration of the tissues inthe operating area. In the maxilla, the palate


2p71-79.QXD 10/01/2005 11:33 Page 75

PRACTICE

must be well infiltrated to anaesthetise thegreater palatine nerve. The incisive papilla andcanal must also receive sufficient anaestheticsolution to block the long sphenopalatine nerve.The local anaesthetic should be applied at least10 minutes prior to surgery, to allow profoundanaesthesia and maximum haemostasis.

Soft-tissue managementThe design of the surgical flap should permit anunobstructed view of the operating area andpermit easy access for instrumentation. The following points need to be considered:1. The blood supply to the flap and adjacent

tissues must be sufficient to prevent tissuenecrosis when it is repositioned.

2. The edges of the flap should lie over soundbone and not cross any void; otherwisebreakdown may occur and defective healingwill result.

3. Relieving incisions should be vertical, andshould not cross any bony eminence, forexample the canine eminence, as healingwill be poor, particularly if there is a dehis-cence or fenestration present.

4. The incision must be clean, so that the flapcan be reflected without any tearing of themargins.

5. The flap should always be full thickness andextend to the gingival sulcus. The periodon-tal tissues should be healthy, as healing willbe affected by any overt disease.

There are several designs of flaps, and, whilstthe choice may depend upon the size of thelesion, the periodontal status and the state of thecoronal tooth structure, it usually depends uponthe operator’s preference

Full mucoperiosteal flapThis design of flap provides the best possibleaccess to all surgical sites, and can be either arectangular flap with mesial and distal verticalrelieving incisions, or triangular with just one.The former usually provides better access to theroot apex in the anterior part of the mouth,though when operating on posterior teeth thedistal relieving incision is not usually neces-sary, and may prove difficult to suture in thelimited space available. The vertical relievingincisions are made firmly down the line angleof the teeth into the gingival crevice, taking inthe papilla. The horizontal incision is madealong the gingival crevice. The flap is thencarefully reflected with a periosteal elevatorlifting the periosteum with it from the bone.(Fig. 11a).

Semilunar flapThis flap, where an incision was made in a semi-circle from near the apex of the adjacent tooth,onto the attached gingival, and finishing nearthe apex of the tooth on the other side, is men-tioned purely for historical purposes, and is nolonger recommended. Its main disadvantage isthe scarring which invariably accompanies thisdesign. However, problems also frequentlyoccurred if the margins of the bony cavityextended across the incision line because thelesion proved to be much larger than was origi-nally apparent (Fig. 11b).

Luebke–Oschenbein flap The Luebke-Oschenbein flap was designed toovercome some of the disadvantages of thesemilunar flap. A vertical incision is made downthe distal aspect of the adjacent tooth to a point

Fig. 11 The outline for the incision to raise a) a full muco-periosteal flap, b) a semilunar flap (not recommended),and c) the Luebke-Oschenbein flap

a

bc


2p71-79.QXD 10/01/2005 11:35 Page 76

PRACTICE

about 4.0 mm short of the gingival margin. Thehorizontal incision is scalloped following thecontour of the gingival margin through theattached gingivae to the distal aspect of the toothon the other side. The incision must always beextended to the other side of the fraenum and thedistal aspect of the adjacent maxillary central orlateral incisor to avoid a vertical incision next tothe fraenum (Fig. 11c).

The flap affords an excellent view of the oper-ating area. However, it still has the disadvantagethat the margins of the bony cavity might extendacross the incision line, as can happen with thesemilunar flap. It is essential to check if there isany periodontal pocketing, as breakdown willthen be inevitable. The aim of this flap design isto preserve the integrity of the gingival margins ifthere are crowns on the teeth. Scarring may againbe a problem with this type of flap.

Whatever design is used, the raised flap shouldbe protected from damage during the operation,and should not be allowed to become desiccated.

Hard-tissue managementIf the lesion has perforated the cortical plate, thenlocation is a fairly simple matter. However, if thisis not the case, then measurement of the toothfrom the radiograph taken with a long-cone par-alleling technique must be made. Initially, a largesize round bur, cooled by copious water or sterilesaline, may be used to provide small, shallowexploratory holes to locate the site of the apexand the lesion. This must be done very carefully,to avoid damaging the root surfaces of the teethin the immediate area. Alternatively, a round bur,again carefully cooled, may be used to locate theapex by paring away the cortical bone over theapex. The bone is shaved away with a very lightmotion to reduce the heat generated and improvevisibility. Sufficient bone should be removedusing the bur and curettes until good visualaccess to the root end is obtained.

Periradicular curettageThe object of this procedure is to remove anysoft-tissue lesion with curettes from around theroot apex. It may not be possible to remove all thesoft tissue until the root end has been resected.

Periradicular curettage used to be a routineoperation carried out by many practitionersafter completion of a root canal filling. Therationale for this is no longer accepted, becauseif the root filling has been carried out success-fully and the canal system has been sealed, thenhealing of the lesion will take place without surgical intervention.

When undertaking periradicular surgery, asmuch as possible of the periapical lesion shouldbe removed. However, the soft tissues in a periapical lesion are essentially reparative anddefensive in nature and if other anatomical structures are liable to be damaged some tissuemay be left. This is fortunate as, technically, it isdifficult to remove every trace of the lesion, especially if it is firmly attached to the wall of thebone cavity.

Pathological material removed should be sentfor histopathological examination with full clinical details.

ArmamentariumFor all surgical procedures, instruments shouldbe set out, preferably in the order in which theywill be used. A typical layout is shown in Fig. 12,and includes the modern microsurgical instru-ments. Magnification, with either optical loupesor a surgical microscope, is preferable.

Resection of the rootThe aim of resection is to present the surface ofthe root so that the apical limit of the canal canbe visually examined and to provide access forretrograde cavity preparation. Approximately3 mm of root is removed which will includealmost all lateral canals.10 It is not necessary toresect the apex to the base of the bony cavity. Iftoo much root is removed, then a greater cross-section of the canal will be revealed, exposing alarger area of filling material to the tissues, andthus reducing the chances of successful healing.The amount of available root length has to beconsidered for any future post crown construc-tion. There is also an inherent disadvantage asthe crown—root ratio is reduced, which mayaffect the adaptive response of the periodontalligament to excessive occlusal forces.

A straight fissure bur is used with copious waterspray at right angles to the long axis of the tooth.Older textbooks may describe bevelling of the cutroot surface at approximately 45° to the long axisof the tooth. This is no longer recommended asthis form of resection may result in both incom-plete removal of the apical delta, and unnecessaryenlargement of the exposed root canal.11 Magnifi-cation is strongly recommended for this proce-dure, both for accuracy in visualising the trueangulation of the long axis, and also for detailedinspection of the cut root surface and root canal.

Retrograde cavity preparationRoot-end preparation should ideally be performedwith a piezo-electric ultrasonic handpiece. If thisis not available then a small, round bur should beused in a miniature-headed handpiece, to preparea single surface cavity to include the entire rootcanal. Care must be taken to ensure that the canalis penetrated sufficiently far for an effective sealto be placed. Inaccuracy may result in a cavity

Fig. 12 The sterile instrumentsnecessary for periradicular surgeryshould be laid out as shown beforesurgery commences. These includemicromirrors and other specialistinstruments for performing suchsurgery using a surgical operatingmicroscope


2p71-79.QXD 10/01/2005 11:36 Page 77

PRACTICE

that is both too large and too shallow. The clini-cian practising without the aid of magnificationmust be aware of these difficulties, and the conse-quent reduction in prognosis of the surgery.

It is now recommended therefore that the ret-rograde cavity is prepared with speciallydesigned ultrasonic tips used in a piezo-electrichandpiece. These were first introduced in theearly 1990s and the KiS® tips are illustrated inFigure 13.12 Used with a gentle planing motionalong the canal configuration, at a low powersetting, a depth of 3 mm may be prepared quick-ly and cleanly. The cavity should be examinedcarefully before proceeding to restoration.

Retrograde fillingBefore the retrograde filling is inserted,haemostasis must be achieved. Dry epinephrine-impregnated cotton wool balls may be placed intothe bony cavity, and will also provide a barrier toprevent accidental loss of excess filling materialaround the root. Bone wax or ribbon gauze mayalso be used to isolate the root tip. If gauze is used,it may be wetted with local anaesthetic solutionor saline once it is in place, then dabbed dry witha cotton wool pledget. Any excess filling materialis more easily retained by the damp gauze.

A biologically compatible material should beused, and amalgam is no longer recommended. Areinforced zinc oxide–eugenol cement such asIRM (modified by the addition of 20% poly-methacrylate) or Super EBA (modified with theaddition of ethoxybenzoic acid) is recommended.Reinforced glass-ionomer cements or compositeresin may be used, although these materials aremore technique sensitive.

However, especially when microsurgery isbeing employed with appropriate magnifica-tion, mineral trioxide aggregate (MTA) (Fig. 14)is recommended.5 It is the least toxic, the mostbiocompatible, hydrophilic and gives the bestseal. The root end should be dried with paperpoints or a fine air syringe, and the materialmay be placed in small increments using a carrier such as the one illustrated in Figure 16a.Alternatively, the MTA may be condensed into atube shape using the device illustrated in Figure16b, when it may be carried to the operation site on a probe. Once placed and compacted into the cavity, a damp cotton woolpledget may be used to compress the materialand remove excess. Note carefully that the dental surgery assistant must ensure that allinstruments, especially the carriers, are thor-oughly cleaned of every trace of MTA immedi-ately following surgery, or they may becomeclogged and rendere useless.

Whichever material is selected for the restora-tion, it should be thoroughly compacted into thecavity with a small plugger to ensure a dense fill,and burnished with a ball-ended instrument to asmooth finish. The bony cavity should be care-fully debrided to ensure that all materials anddebris are removed.

Replacement of flap and suturingOnce the retrograde filling has been completed,the packing around the root removed and finaldebridement carried out, the flap may be suturedinto place. Where possible, synthetic monofila-ment sutures should be used as these do not causewicking of bacteria into the surgical site and lead

Fig. 13 Ultrasonic KiS®tips for root-end cavitypreparation

Fig. 14 The commercial presentationof mineral trioxide aggregate

Fig. 15 a) The Dovgan applicator for MTA, available with either a straight or flexible tip. b) A block for compactingand manipulating mixed MTA

a b


2p71-79.QXD 10/01/2005 11:37 Page 78

PRACTICE

to better healing than when silk sutures are used.Resorbable sutures are not recommended.

The vertical relieving incisions should berepaired with interrupted sutures. The gingivalmargin should be carefully repositioned andsutured with sling sutures. Commencing at abuccal papilla, the suture is taken through theembrasure, around the tooth and back throughthe adjacent embrasure to enter the next papilla.The suture is then taken back round the tooth tothe original site and the knot tied over the buccalpapilla. The sutures may be removed after 48 hours, and certainly no more than 3–4 days,when the periodontal fibres will have reattached.Sutures left longer than this may actually delayhealing by wicking.

POST-OPERATIVE CAREImmediately following suturing, the tissuesshould be firmly compressed with a damp gauzefor 5 minutes. Post-operative swelling can bereduced by the continued application of coldcompresses (crushed ice cubes placed in a plasticbag surrounded by a clean soft cloth) for up to6 hours. Post-operative pain may be controlledby the administration of a long-acting localanaesthetic at the end of the surgery, and by theprescription of non-steroidal anti-inflammatorydrugs (NSAIDs). Chlorhexidine mouthwashshould be used to keep the surgical site cleanuntil the sutures are removed. The prescriptionof antibiotics is only necessary if required by thepatient’s medical history.

SURGICAL OUTCOMES A radiograph should be exposed either immedi-ately following treatment or when the suturesare removed for comparison with future films toassess healing. Ideally, cementum and periodon-tal ligament should regenerate over the resectedroot apex, although in many cases repair occursby the formation of a fibrous scar. It is reportedthat success rates may vary between 30% and80%.13,14 It should be noted, however, that

recent papers have reported treatment using themodern techniques described here to have success rates as high as 92%.15

Should failure occur, the cause must be established before further intervention. Repeatsurgery has a low success rate, as can be seen inFigure 16. All surgical treatment should, ofcourse, be encompassed within audit and clini-cal governance, both for the patient and theclinician (Fig. 17).

1 Kim S. Principles of endodontic surgery. Dent ClinNorth Am 1997; 41: 481–497.

2 Peters L, Wesselink P. Soft tissue management inendodontic surgery. Dent Clin North Am 1997; 41:513–528.

3 Chindia M L, Valderhaug J. Periodontal statusfollowing trapezoidal and semilunar flaps inapicectomy. East African Med J 1995; 72: 564–567.

4 Morgan L A, Marshall J G. A scanning electronmicroscopic study of in vivo ultrasonic root-endpreparations. J Endod 1999; 25: 567–570.

5 Torabinejad M, Pitt Ford T R, Abedi H R, Kariyawasam S P, Tang H M. Tissue reaction toimplanted root-end filling materials in the tibia andmandible of guinea pigs. J Endod 1998; 24: 468–471.

6 Kim S. Endodontic Microsurgery. Chapter 19 in Cohen S,Burns R C, Pathways of the Pulp. St Louis: Mosby 2002.

7 Webber R T. Apexogenesis versus apexification. DentClin North Am 1984; 28: 669–697.

8 Layton S, Korsen J. Informed consent in oral andmaxillofacial surgery: a study of the value of writtenwarnings. Br J Oral Maxillofac Surg 1994; 32: 34–36.

9 Martin M V, Nind D. Use of chlorhexidine gluconate forpre-operative disinfection of apicectomy sites. Br Dent J1987; 162: 459–461.

10 Hsu Y Y, Kim S. The resected root surface. The issue ofcanal isthmuses. Dent Clin North Am 1997; 41: 529–540.

11 Gilheany P A, Figdor D, Tyas M J. Apical dentinpermeability and microleakage associated with root endresection and retrograde filling. J Endod 1994; 20: 22–26.

12 Carr G. Common errors in periradicular surgery. EndodRep 1993; 8: 12–16.

13 Jansson L, Sandstedt P, Laftman A C, Skogland A.Relationship between apical and marginal healing inperiradicular surgery. Oral Surg, Oral Med, Oral Path,Oral Rad, Endod 1997; 83: 596–601.

14 Rud J, Andreasen J O, Jensen J E. Radiographic criteriafor the assessment of healing after endodontic surgery.Int J Oral Surg 1972; 1: 195–214.

15 Maddalone M, Gagliani M. Periapical endodonticsurgery: a 3-year follow-up study. Int Endod J 2003;36: 193–198.

Fig. 17 The radiograph shown at: a) was exposed immediately post-surgery and b) The radiographtaken 1 year later, as part of surgical audit, shows complete healing

Fig. 16 This tooth has been subject to repeated surgicalprocedures, without success

a b


2p71-79.QXD 10/01/2005 11:38 Page 79

PRACTICE

Endodontic problems

If modern clinical techniques were carefully followed, many common endodontic problems would never occur. Incorrectlydesigned access cavities may make root canals both difficult to identify and to instrument. Careful study of the pre-operativeradiograph is essential. Various aids are available to remove fractured instruments and failed root fillings, but the problemmust first be correctly diagnosed. As more patients seek cosmetic procedures, the practitioner should be familiar with the‘walking bleach’ procedure, again after careful diagnosis of the cause of the discolouration. The practitioner should also befully aware of the prognosis for this and other endodontic procedures.

Most problems in root canal treatment could have been avoided with care and attention totreatment principles. Careful examination of the pre-operative radiograph is essential.

It is possible to remove most fractured instruments, posts and failed root filings if the correctaids are to hand, and magnification is available.

It is essential that practitioners know the prognosis for different endodontic procedures, bothfrom the endodontic literature and their own clinical experience.

I N B R I E F

Endodontics is a skill requiring the use of deli-cate instruments in confined spaces. Inevitably,problems will occur, but many of these areavoidable providing the operator exercises careand patience. A few tips on how to overcomesome of these problems will be given in this part.Should the reader require a more wide-rangingand detailed account, specialist endodontic text-books on this subject may be referred to.1

ACCESSIt is important to have good visual access and suf-ficient space to allow direct line access into theapical third of the root canal. A useful way ofassessing a patient for molar endodontics is thatthe operator should be able to place two fingersbetween the maxillary and mandibular incisors. Ifthis is not possible owing to a small mouth or lim-ited opening, then it may be unwise to commenceroot canal therapy. Assessing access for posterior

surgical endodontics may be done by retractingthe lip at the corner of the mouth with a finger;the surgical area should be directly visible.

The general guidelines for access cavities havealready been discussed in Part 6. However, thereare occasions when these should be adapted tosuit a particular case. Inadequate access will leadto poor treatment and, unless the endodontictreatment is successful, further restoration of thetooth is irrelevant.

Before cutting the access cavity, the extentand type of final restoration should be borne inmind. If an anterior tooth will require a crownfollowing the root treatment, the access cavitycould be cut on the labial surface (Fig. 1). In pos-terior teeth it may be advantageous to reduce thewalls, if either they are already weakened orthere is a crown or root fracture.

LOCATING AND NEGOTIATING FINE CANALS

12













Fig. 1 Unconventional access cavities may be used in some situations. a) A resin-retained bridge had been fitted toreplace UL1 (21) lost through trauma. When a periapical lesion developed related to UR1 (11), an access cavity was cutthrough the incisal edge. b) The last standing teeth are to be cut down for overdenture abutment.

a b



1*Clinical Lecturer, Department of Adult DentalCare, Glasgow Dental Hospital and School, 378Sauchiehall Street, Glasgow G2 3JZ*Correspondence to: Peter CarrotteEmail: [email protected]


BRITISH DENTAL JOURNAL VOLUME 198 NO. 3 FEBRUARY 12 2005 127

3p127-133.qxd 19/01/2005 13:29 Page 127

Fig. 2 A radiograph of tooth UL1(21), which suffered trauma 5 yearspreviously, showing no apparent signof a root canal system.

Many root canals, particularly in the elderlypatient, are difficult to locate. The pulp chambersmay be sclerosed or contain large pulp stonesand the root canals may be so fine that evenwhen located they are difficult to negotiate.

Dentine deposition occurs as a response toany moderate injury to the pulp, in particularluxation injuries. Initially, the pulp chamberreduces in size, followed by a gradual narrow-ing of the root canals. The incidence of pulpalnecrosis following canal obliteration is not highand so does not warrant intervention by electiveroot canal treatment.2

Radiographs of teeth showing apparent totalcanal obliteration are deceptive (Fig. 2). Cvek et al.report a study in which attempts were made tolocate and negotiate root canals which were notvisible on the pre-operative radiographs.3 In 54incisors with periapical lesions, the root canalwas located and treated in all but one of them.

These narrow canals may take time to locate.The pre-operative radiograph contains usefulinformation: the size, curvature and position ofthe root canal(s) in relation to the pulp chambermay be noted. A meticulous search must bemade of the floor of the pulp chamber witheither an endodontic (DG16) probe or an 08 or10 file. The floor of the pulp chamber is darkerthan the walls and the canal entrances are situ-ated, in posterior teeth, at each corner. Fibre-optic light, transilluminating the tooth, andmagnification using either binocular loupes oran operating microscope as discussed in Part 4are also of assistance.

If the canal cannot be located, an ultrasonictip as described in Part 5 may be used to breakdown secondary dentine from the floor of thepulp chamber around the anticipated canalopening. As a final resort it will be necessary todrill using a small, round bur in a slow runningstandard handpiece. A bur hole, approximately2 mm in depth, is then drilled at the expectedsite of the canal along the main axis of the root.A radiograph is taken with the bur in situ andthe direction of the bur corrected if furtherdrilling is necessary. This can be a frustratingexercise and numerous fine files will bedamaged as the tips curve in the round shape

produced by the bur. The associated risks of per-foration do mean that this really is a ‘last resort’,as shown in Figure 3.

Once the entrance has been located, the nextstep is to negotiate the canal using a fine instru-ment. A curve is placed at the tip of an 06 or 08hand file. It is useful to dip the tip of the instru-ment into a lubricant such as Hibiscrub. Theinstrument is gradually advanced into the canalusing a small, contrarotating, ‘watchwinding’movement to advance the file. Force should notbe used. The curve in the instrument tip willseek the path of least resistance and allow theinstrument to penetrate further into the canal. A push—pull filing motion may then be used tofree coronal obstructions in the canal. The file isremoved, copious irrigation used and the proce-dure repeated until the canal is negotiated to theworking length. If an electronic apex locator isnot being used it will be necessary to enlarge thecanal with successively larger fine instrumentsup to a size 15 before confirming the workinglength, as an 06 file may not be seen accuratelyon a diagnostic radiograph.

EDTA paste (ethylenediamine tetra-acetic acid)is not recommended for the initial negotiation ofthe canal, as it is a chelating agent. The walls ofthe dentine will be softened, which means a falsecanal could be cut. EDTA paste is, however,extremely useful when preparing the canal wallsonce the full length has been negotiated.

LEDGED OR BLOCKED CANALSIncorrect technique in preparation can lead toeither obstruction of the root canal with pulpaldebris, compacted dentine and other debris, orthe formation of a ledge in the wall of the canal.

In the case of a ledged canal (Fig. 4), a curveshould be placed near the tip of a fine handinstrument, the canal irrigated with sodiumhypochlorite, and the instrument inserted intothe canal. The notch in the rubber stop shouldbe aligned with the curve so that the instrumenttip may be directed away from the ledge andgradually advanced with small contrarotatingmovements. Once the instrument is beyond theledge a short push–pull filing motion is used toreduce the ledge in the curve before removing

ENDODONTICS

Fig. 3 The operator was unable tolocate the access to the mesiobuccalcanal. A small, round bur was used toexplore the area, and an orifice wasfound. Unfortunately a radiographrevealed that a perforation into thefurcation had been created. As thepulp chamber was clean and wellisolated, the perforation wasrepaired with resin-modified glass-ionomer cement and the toothremained symptomless.

128 BRITISH DENTAL JOURNAL VOLUME 198 NO. 3 FEBRUARY 12 2005

3p127-133.qxd 19/01/2005 13:31 Page 128

Fig. 5 This tooth has been root filledusing both silver points and gutta-percha. The operator must be able todistinguish between various root-filling materials by theirradiographic appearance.

the file. A lubricant such as EDTA paste is usefulto help remove the ledge. This is not a difficultprocedure once the ledge has been bypassed. A canal that has been blocked with pulpal ordentine debris may well be impossible to negoti-ate. Copious irrigation, the use of EDTA pasteand a very fine instrument may be tried. Thedanger is of either packing the debris harder intothe canal or creating a false canal.

RE-ROOT TREATMENTA root filling may have to be removed and thetooth retreated for a variety of reasons. Thepatient may be experiencing symptoms, a peri-apical radiolucency may be increasing in size, orthe coronal restoration may require replacing in atooth where the root filling is inadequate. What-ever the reason, the first step is to identify the typeof filling material that has been used (Fig. 5) andto assess the difficulty of the procedure. Themethod used to remove the previous root fillingwill depend on the type of material used.

PasteA soft root-filling material may be removed easilywith Hedstroem files and copious irrigation.

CementSome cements set hard and have apparently nosolvent and, as a result, are almost impossible toremove. The first stage in attempting to removea cement is to flood the canal entrance withchloroform or xylene and use an endodonticprobe and then Hedstroem files. If this fails, thecoronal 2–3 mm can be removed with a smallrosehead bur followed by files. Alternatively,ultrasonics may be used to break down thecement and flush out the debris. It may, howev-er, prove impossible to negotiate a canal filledwith a hard setting cement.

Gutta-perchaGutta-percha is simple to remove. Gates–Gliddenburs may be used first to gain access to the rootcanal. The burs both cut away gutta-percha, andsoften it by the frictional heat of rotation. Thereare various solvents for gutta-percha, which maybe dispensed into a Dappens dish and picked upon the tip of each instrument. Chloroform,halothane and xylene may be available in the sur-gery, or oil of eucalyptus and oil of turpentine areboth effective. Once access has been made it isusually possible to remove the remainder of thegutta-percha with conventional filing techniques.

Alternatively, nickel-titanium rotary instru-ments are very efficient for softening and remov-ing gutta-percha from canals that will accommo-date them. Initial exploration with hand files isnecessary to create room for the cutting flutes ofthe instruments. They should not be used to path-find. The piezo-electric ultrasonic machines arealso useful as their heat generation aids removal ofsoftened gutta-percha. Specially designed tips areavailable for this procedure.

If the original gutta-percha filling has beenextended beyond the apical foramen, removal

may prove impossible. One method proposed forthis situation involves first creating a gapbetween the material and the wall of the canalwith a canal probe. A Hedstroem file may thenbe carefully ‘screwed’ into the space. A secondand, if possible, third file are similarly insertedinto the mass of the gutta-percha. The handles ofthe files are grasped, and a steady withdrawalforce exerted to remove the gutta-perchapoint(s). Hedstroem files are needed to grip andpull back the gutta-percha.

Metal pointsThe method of removing silver or titaniumpoints is dictated by their position within theroot canal. Silver points are easier to remove ifthere has been leakage of tissue fluids into thecanal and corrosion has occurred.

The simplest situation is when the coronal endof the point protrudes far enough into the pulpchamber so that it may be grasped by eitherSteiglitz forceps (Fig. 6), narrow-beaked arteryforceps or fine pliers.

If the point lies in the root canal below thepulp chamber but in a straight part of the canal,attempts should be made to bypass and eitherremove the point or incorporate it into the rootfilling. A size 08 or 10 file or reamer is used, andthe tip is coated with EDTA paste. If the pointcan be bypassed, it can frequently be removed

ENDODONTIC PROBLEMS

Fig. 4 A diagram of a canal with aledge in the outer curve, showinghow the tip of a pre-curved file mayenter the ledge. If the file is rotatedthrough 180° the curved tip willfollow the original canal.


3p127-133.qxd 19/01/2005 13:31 Page 129

with Hedstroem files or by using an ultrasonictechnique. CPR® Ultrasonic tips (described inPart 5) are ideal for accessing and dislodgingpoints and broken instruments.

Alternatively, two fine devices are available toassist in removal of such impediments. The Can-cellier kit contains four fine hollow tubes whichmay fit over a loosened point in the canalenabling its withdrawal. The Meitrac EndoSafety System involves the use of a mini-trephine to free the tip of the fractured point.This may then be gripped using two ‘locking’tubes and withdrawn.

Unless an operating microscope is used, it isseldom possible to remove a point which islodged in the apical third of a curved root canal.Attempts should be made either to bypass thefragment and incorporate it into the root filling,or condense gutta-percha vertically up to theobstruction, with a view to apical surgery shouldsigns of failure occur.

FRACTURED INSTRUMENTSThe time required to remove or bypass a frac-tured instrument from the root canal far out-weighs the simple precautions that should betaken routinely to prevent such an occurrence.The simple rules which will prevent instrumentfracture are as follows.1. Each time an endodontic instrument is picked

up it should be visually checked for any dam-age or deformation of the twisted flutes (Fig.7). The assistance of a well-trained dentalnurse can be invaluable. Damaged instru-ments should be discarded immediately.

2. Never force an instrument in the canal.3. Do not miss out sizes. Although appearing

small, moving from a size 10 to a size 15 fileinvolves an increase in tip diameter of 50%.It is preferable to repeat the use of the smallerfile than apply excess force to the next size.

4. When using the balanced force technique,limit rotations to 60° as described by Roane et al. and never rotate an instrumentmore than one quarter turn in a clockwisedirection.4

The techniques used for removal of a frac-tured instrument are similar to those describedpreviously for metal points. In addition, theMasserann was specifically designed to extractmetal fragments from root canals. The Masser-ann kit (Fig. 8) consists of a number of trepanswith a range of diameters from 1.1 mm to2.4 mm. The trepans are hollow tubes designedto cut a trough around the metal fragment (Fig.9). Note that the trepans are designed to be usedwith an anticlockwise rotation. This will assistwith the removal of any threaded materialswhich will have a conventional thread. Theoperator should be particularly aware of this asa potential problem if attempting to remove afractured Hand File of Greater Taper, whichhave a reverse thread.

The trough usually has to be cut along at leasthalf the length of the fragment before it is suffi-ciently loosened to allow its extraction. It is rec-ommended that the trepan is operated by hand,using the special handle provided, and notplaced in a handpiece. A feeler gauge from thekit is used to judge the size of the trepanrequired. EDTA paste will help to lubricate andsoften the dentine. The kit also contains aMasserann extractor, which is placed over theend of the loosened fragment so that it may begripped and removed. If the fragment is toolarge for the extractor, then a size smaller trepanmay be forced over the end of the fragment,which is then gripped firmly enough to allow itswithdrawal from the canal. However, the opera-

Fig. 8 A Masserann kit for removal of fracturedinstruments and posts.

Fig. 9 The tip of the Masseranntrepan showing the cutting flutes,designed to cut in an anticlockwisedirection.

Fig. 10 Post extractors for dismantling post-crowns: a) the Ruddle, and b) the Eggler systems.

Fig. 7 Files should be visually inspected for damage tothe flutes every time they are removed from the tooth forcleaning.

ENDODONTICS

Fig. 6 Steiglitz forceps have longnarrow beaks, and are useful forgrasping broken instruments in thepulp chamber.

b

a


3p127-133.qxd 19/01/2005 13:32 Page 130

tor must weigh the benefits of this procedureagainst the damage to the trepan.

A fractured instrument remaining in a canaldoes not mean that the attempt at root treatmentwill fail. It has been demonstrated that, providedthe remainder of the root canal is filled conven-tionally, the success rate is not significantlyaffected.5,6

POSTSA post may have to be removed because eitherthe tooth requires (re)root filling or the post hasfractured. The procedure presents problems asthere is a danger of fracturing or perforating theroot of the tooth. Threaded posts which havefractured can be removed by cutting a groove inthe post end and unscrewing. It is possible toextract a smooth-sided post and core using apost extractor (Fig. 10).

A piezo-electric ultrasonic system, used withspecial tips, should first be used at the appropriatepower setting. Moving the tips around the base ofthe post at moderate power will remove cementaround the post. A different tip may then be usedto apply maximum vibratory energy to the post inan attempt to vibrate the post loose directly.

With the Eggler system, the core must first beshaped so that its sides are parallel and capableof being gripped. The mesial and distal shouldersof the crown preparation must be cut to the sameheight so there is no torsional force. The postextractor is then placed over the post and the

screw tightened onto the core; the feet are thenlowered on to the shoulders of the preparationby turning the end knob. Several more turns willease the post out of the post hole.

With the Ruddle system, a trephine is used toproduce a parallel side in the post, which is thengrasped in a matching sized thread cutting tap toa maximum depth of 3 mm. The post removalpliers are placed over a rubber cushion, and gen-tly tightened. If removal is difficult, furtherultrasonic energy may be applied. As with allsuch instruments, there is a danger of root frac-ture, and expertise should be gained in a techni-cal laboratory before attempting these tech-niques in a clinical situation.

A fractured post lying within the root canalmay either be drilled out using a high-speedhandpiece, which is a hazardous procedure, orremoved with a Masserann kit as described ear-lier. Figure 11 shows the initial radiograph ofthe fractured post, and the item successfullyremoved with the Masseran kit.

VERTICAL ROOT FRACTURE Although infrequent, this problem may be diffi-cult to diagnose. The patient may present withmild symptoms, or it may appear that the rootcanal treatment has not been successful. Caseshave been reported where the first indication ofa vertical root fracture has been when a muco-periosteal flap has been raised to carry out peri-radicular surgery on an apparently persistentlesion. Figure 12 in Part 2 shows a tooth withsuch a fracture which had to be extracted.

The diagnosis can, however, be suspectedwhen a radiograph shows bone loss extendingall around a root or a tooth, as in Figure 12. Thevertical defect has led to bacterial contamina-tion of the entire tooth surface.

THE DISCOLORED ROOT-FILLED TOOTHBleaching and tooth-whitening procedures arerapidly becoming a part of every dentist’spractice. The routine use of such materials inrestorative dentistry is outside the scope of thistext, and the subject is comprehensively cov-ered in other books.7,8 However, teeth whichhave been root filled may darken for various

Fig. 12 A radiograph of a molarwith a vertical root fracture,showing the pathognomonicappearance of periodontitissurrounding the entire root.

ENDODONTIC PROBLEMS

Fig. 11 A fractured post successfully removed with theMasseran kit.


3p127-133.qxd 19/01/2005 13:33 Page 131

`

ENDODONTICS

reasons, and may benefit from internal bleach-ing using the technique known as ‘walkingbleach’. An illustration of the potential can beseen in Figure 13.

It is essential wherever possible to identifythe cause of the discoloration. Some of thosespecifically due to endodontics may be:9

• Internal haemorrhage within the dentinefollowing trauma;

• Seepage of toxins from the infected pulpalcontents;

• Staining from medicaments, cements, etc.,particularly those containing silver;

• The optical effects of dehydration.

Briefly, the normally recommended technique isas follows:1. Clean and polish all the teeth thoroughly to

remove any extrinsic stain.2. Match the existing shade of the tooth with a

ceramic shade guide (if possible with anintra-oral photograph of the tooth and tab).

3. Isolate the tooth with rubber dam, sealingthe margins carefully around the teeth with acaulking agent.

4. Remove the restoration from the access cavity,ensuring that all aspects are clean.

5. Clean out all endodontic materials from thepulp chamber, to a depth of 2 mm into theroot canal.

6. Seal the root filling with a layer of glass-ionomer cement of the lightest shade.

7. Soak a cotton pledget in 30% hydrogenperoxide and place in the access cavity.

8. Apply a heated instrument to the pledget,and repeat the process several times. (Notethat in a recent comprehensive review of thisprocedure Attin et al. suggest that the use of30% hydrogen peroxide and the applicationof heat may both contribute to the initiationof cervical resorption.10)

9. Place a mixture of sodium perborate and 3%hydrogen peroxide in the pulp chamber, andseal it in place with a non-eugenol tempo-rary cement. This constitutes the ‘walking-bleach’ phase of the procedure.

10. Review the patient after one week, andmeasure the change in colour.

11. The procedure may require repeating severaltimes.

12. The access cavity should be restored com-pletely with the lightest paediatric shade ofcomposite resin.

PROGNOSIS IN ENDODONTICSAll endodontic procedures should be reviewedas part of audit and clinical governance. Anassessment of the degree of healing or otherwisemust be made, and unsatisfactory results mayrequire either further monitoring or retreatment.However, it should be noted that Ørstavikreported that over 75% of apical periodontitislesions developing after endodontic treatmentcan be observed radiographically after oneyear.11 It may be considered therefore that ifhealing is evident after one year, further radi-ographic monitoring is not indicated.

One method of monitoring would be toemploy the Periapical Index (PAI) described byØrstavik at al.12 Standard radiographic viewsare presented of five apical conditions, and theoperator compares their own result with thesestandards. A score of 1 indicates normal periapi-cal appearance; 2 indicates slight disorganiza-tion of the bone texture; 3 loss of bone andunusual bone pattern; 4 shows classic periapicalperiodontitis; and 5 is similar, but with obviouswider spread.

Many studies have been reported on the suc-cess of endodontic treatment, many assessing

Fig. 13 Internal bleaching has beenused to lighten this root canaltreated central incisor. Figurecourtesy of Dr M Elkhazindar,Glasgow Dental Hospital.

Table 1 Overview of success in endodontic treatment (From Friedman12)

Treatment procedure Weighted average success of Weighted average success of reports in approximately the reports in approximately the past past 50 years 10 years

Endodontic treatment of 34 studies 6 studiesteeth without periapical Range from 100% to 67% Range from 100% to 88%periodontitis Weighted average 91% Weighted average 93%

Endodontic treatment of 38 studies 8 studiesteeth with periapical Range from 96% to 38% Range from 94% to 46%periodontitis Weighted average 76% Weighted average 77%

Endodontic treatment of 6 studies since 1987teeth with periapical Range from 86% to 69% periodontitis using calcium Weighted average 79%hydroxide intervisit dressing

Orthograde endodontic 9 studies 3 studiesretreatment in teeth with Range from 88% to 48% Range from 74% to 56%periapical periodontitis Weighted average 70% Weighted average 62%

Periradicular surgery in 29 studies 11 studiesteeth with periapical Range from 95% to 30% Range from 81% to 30%periodontitis Weighted average 59% Weighted average 63%


3p127-133.qxd 19/01/2005 13:33 Page 132

ENDODONTIC PROBLEMS

the result against the PAI. Friedman reports acomprehensive review of these studies, and theweighted averages are summarized in Table 1.13

Particular note should be made of the signifi-cantly reduced weighted average prognosiswhen treating teeth presenting with an estab-lished area of periapical periodontitis seen onradiographic examination. These figures shouldbe studied by the clinician, and an estimate ofthe likely prognosis should form part of the pro-cedure of obtaining informed or valid consent.

1. Guttman, J L, Dumsha T C, Lovdahl P E, Hovland E J.Problem Solving in Endodontics. 3rd Ed. St Louis:Mosby, 1997.

2. Andreasen J O, Andreasen F M. Chapter 9 in Textbookand colour atlas of traumatic injuries to the teeth. 3rdEd. Denmark: Munksgard, 1994.

3. Cvek M, Granath L-E, Lundberg M. Failures and healingin endodontically treated non-vital anterior teeth withpost-traumatically reduced pulpal lumen. Acta OdontScand 1982; 40: 223–228.

4. Roane J B, Sabala C L, Duncanson M G. The balancedforce concept for instrumentation of curved canals.J Endod 1985; 11: 203–211

5. Crump M C, Natkin E. Relationship of broken root canal instruments to endodontic case prognosis: aclinical investigation. J Am Dent Assoc 1970; 80:1341–1347.

6. Lumley P J. Management of silver points and fracturedinstruments. CPD Dentistry 2000; 1: 87–92.

7. Greenwall L. Bleaching techniques in restorativedentistry. London: Martin Dunitz, 2001.

8. Sheets C G, Paquette, J M, Wright R S. Chapter 21 inCohen S & Burns R C. Pathways of the Pulp, Eighth Ed.St Louis: Mosby, 2002.

9. Nathoo S A. The chemistry and mechanisms ofextrinsic and intrinsic discoloration. J Am Dent Assoc1997; 128: 6S–10S.

10. Attin T, Paqué F, Ajam F, Lennon Á. Review of the current status of tooth whitening with the walking bleach technique. Int End J 2003; 36:313–329.

11. Ørstavik D. Time-course and risk analyses of thedevelopment and healing of chronic apicalperiodontitis in man. Int Endod J 1996; 29: 150–155

12. Ørstavik D, Kerekes K and Eriksen H M. The periapical index: A scoring system for radiographic assessment ofperiapical periodontitis. Endod Dent Traumatol18; 2: 20–34.

13. Friedman S. Treatment outcome and prognosis ofendodontic therapy. In Ørstavik D, Pitt Ford T R, EssentialEndodontology. Oxford: Blackwell Science, 1998.


3p127-133.qxd 19/01/2005 13:34 Page 133

bdj of endo_2005

Documents