reendodontic treatment ( possibilities apexlocators in endodontic therapy)

Reendodontic treatmentReendodontic treatment((possibilities apexlocators possibilities apexlocators

in endodontic therapy)in endodontic therapy)

Retreatment in endodontics

21ST-CENTURY ENDODONTICSEndodontics as a discipline has offered patients the opportunity to maintain their natural teeth. As the population expands and ages, the demand for endodontic therapy can be expected to increase as patients seek dental options to keep their teeth for a lifetime.


Over the past decade, nickel titanium rotary Over the past decade, nickel titanium rotary instrumentation, microscopic endodontics, digital instrumentation, microscopic endodontics, digital radiography, a plethora of obturation systems, and radiography, a plethora of obturation systems, and biocompatible sealing materials have helped biocompatible sealing materials have helped practitioners perform endodontic procedures more practitioners perform endodontic procedures more effectively and efficiently than ever before. effectively and efficiently than ever before.

Diagnosis, in fact, has become more challenging. Diagnosis, in fact, has become more challenging. Overall, case management is more complex as geriatric Overall, case management is more complex as geriatric patients and those who are medically compromised are patients and those who are medically compromised are more inclined to seek treatment to save their teeth. more inclined to seek treatment to save their teeth.


Endodontics has gone through many changes in the past several years. Bacterial culturing of canals, the use of silver points, multiple endodontic visits, radiographic “guessing” of working lengths, and dependence on canal medicaments are fading concepts in endodontic treatment.

Thanks to modern techniques used in endodontics, most of the teeth, which in the past would be removed currently can be saved. Many patients have had bad experiences associated with the "root canal therapy" and in this context often face a dilemma: whether to remove or cure? The latter approach is irreversible and should be treated as a last resort. We tried to make the treatment as light as possible, short and comfortable.

Retreatment in endodontics A variety of advancements in technology,materials,

equipment, and even philosophy have changed how endodontic cases are managed.

Electronic apex locators and surgical microscopes have heightened precision and eliminated much of the uncertainty associated with endodontic procedures. Digital radiography has expanded diagnostic abilities and increased the ability to communicate with patients and other dentists.

Endodontic treatment consists ofEndodontic treatment consists of removing the contents of the chamber and removing the contents of the chamber and

canal system-the pulp (a network of blood canal system-the pulp (a network of blood vessels and nerves) vessels and nerves)

the elimination of bacteria the elimination of bacteria filling tightly root canalsfilling tightly root canals

For that we useFor that we use: : modern tools to process canals modern tools to process canals systems for their filling systems for their filling apex locator to measure the length of the apex locator to measure the length of the

rootroot dental RTG dental RTG endodontics microscopeendodontics microscope

Endodontic ServicesEndodontic Services Root Canal Therapy Root Canal Therapy

With Rotary System With Rotary System With Apex FinderWith Apex Finder

Re-Endodontic Treatment Re-Endodontic Treatment Apicectomy Apicectomy Hemisection Hemisection Re-Implant Endodontic Re-Implant Endodontic

Electronic apex locators

•Prior to root canal treatment at least one undistortedradiograph is required to assess canal morphology.The apical extent of instrumentation and the final rootfilling have a role in treatment success, and are primarily determined radiographically.

•Electronic apex locators reduce the number of radiographs required and assist where radiographic methods create difficulty.They may also indicate cases where the apicalforamen is some distance from the radiographic apex.

The removal of all pulp tissue, necrotic material and microorganisms from the root canal is essential for endodontic success. This can only be achieved if the length of the tooth and the root canal is determined with accuracy. The outcome of treatment of roots with necrotic pulps and periapical lesions is influenced significantly by the apical level of the root filling

Traditionally, the point of termination for endodontic instrumentation and obturation has been determined by taking radiographs. The development of the electronic apex locator has helped make the assessment of working length more accurate and predictable .

The importance of working length

Grove (1930) stated that ‘the proper point to which

root canals should be filled is the junction of the dentin

and the cementum and that the pulp should be severed

at the point of its union with the periodontal membrane’.

The cementodentinal junction (CDJ) is the anatomical

and histological landmark where the periodontal ligament

begins and the pulp ends. Root canal preparation

techniques aim to make use of this potential natural barrier

between the contents of the canal and the apical tissues.

The importance of working length It is generally accepted that the preparation and

obturation of the root canal should be at or short of the apical constriction. An in vivo histological study found that the most favourable histological conditions were when the instrumentation and obturation remained short of the apical constriction and that extruded gutta-percha and sealer always caused a severe inflammatory reaction despite the absence of pain .

The problem clinicians face is how to accurately identify and prepare to this landmark – the ‘working length’ – and achieve maximum success. Epidemiological studies have reported that the best prognosis is when the root filling lies within 2 mm of the radiographic apex (Sjo¨gren et al. 1990). The variations in anatomy of tooth apices both by age and tooth type make this task all the more challenging.

Anatomy of the apical foramen

To appreciate fully the concept of working length, an

understanding of apical anatomy is required. The anatomy of the apical foramen changes with age.

Figure 1a shows a concept of the apex (a), the apex of a younger person (b) and the changing apex due to hard tissue deposition (c).

(a) Position of the apical foramen (adapted fromKuttler 1955). (b) Anatomy of the root apex,

Anatomy of the apical foramen It is generally agreed that there are three distinct aspects of

the apex that must be appreciated. Figure 1b shows these as the tooth apex (1), the apical foramen [major foramen (2)] and the apical constriction [minor foramen (3)] which is also described as the CDJ.

The apical foramen is not always located at the anatomical apex of the tooth. The foramen of the main root canal may be located to one side of the anatomical apex, sometimes at distances of up to 3 mm in50–98% of roots Dummer et al. (1984) reported the mean apex to foramen distance (Fig. 1b, 4) in anterior teeth to be 0.36 mm. The general trend is that the apex to foramen distance is greater in posterior teeth and older teeth than in anterior and younger teeth.

Anatomy of the apical foramen The foramen to apical constriction (Fig 1(b)5) is

approximately 0.5 mm in the younger group and 0.8 mm in the older group for all tooth types

Traditional methods for establishing working length have been (a) the use of anatomical averages and knowledge of anatomy, (b) tactile sensation, (c) moisture on a paper point and (d) radiography

.Radiographic determination of working length has been used for many years. The radiographic apex is defined as the anatomical end of the root as seen on the radiograph, while the apical foramen is the region where the canal leaves the root surface next to the periodontal ligament (American Association of Endodontists 1984).

Anatomy of the apical foramen When the apical foramen exits to the side of the root or

in a buccal or lingual direction it becomes difficult to view on the radiograph.

The preoperative radiograph is essential in endodontics to determine the anatomy of the root canal system, the number and curvature of roots, the presence or absence of disease, and to act as an initial guide for working length. The electronic apex locator is an instrument, which used with appropriate radiographs, allows for much greater accuracy of working length control

ApexlocatorsApexlocators An electronic method for root length determination was first

investigated by Custer (1918).

Third generation apex locators are similar to the second generation except that they use multiple frequencies to

determine the distance from the end of the canal. These units have more powerful microprocessors and are able to process the mathematical quotient and algorithm calculations required to give accurate readings.

The relative values of frequency response method detects the apical constriction by calculating the difference between two direct potentials picked up by filters when a 1 kHz rectilinear wave is applied to the canal.

ApexlocatorsApexlocators Many of the problems with previous generations of Many of the problems with previous generations of apex apex

locatorslocators occurred when the root canal contained moisture- occurred when the root canal contained moisture-rich substances such as exudate, electrolytes like sodium rich substances such as exudate, electrolytes like sodium hypochlorite and the products of hemorrhage. The new hypochlorite and the products of hemorrhage. The new third-generationthird-generation apex locators apex locators have overcome most of have overcome most of these problems, are more user-friendly and require these problems, are more user-friendly and require minimal calibration.minimal calibration.

More importantly is the revelation that modern-day More importantly is the revelation that modern-day apex apex locatorslocators may even be more reliable than radiographic may even be more reliable than radiographic interpretation. Studies evaluating interpretation. Studies evaluating apex locators apex locators have have demonstrated accuracies of working length determination demonstrated accuracies of working length determination to within 0.5 mm from the apical constriction, ranging from to within 0.5 mm from the apical constriction, ranging from 75 percent to 93.4 percent. Nonetheless, using 75 percent to 93.4 percent. Nonetheless, using today’stoday’s apex locator apex locator in conjunction with a radiograph is still an in conjunction with a radiograph is still an extremely effective adjunct for determining working length extremely effective adjunct for determining working length and detecting perforations or root fractures. and detecting perforations or root fractures.

ApexlocatorsApexlocators Current apex locators utilize an alternating current within Current apex locators utilize an alternating current within

the canal and monitor the impedance between periapical the canal and monitor the impedance between periapical tissue and oral mucosa via a lip clip. The circuitry within tissue and oral mucosa via a lip clip. The circuitry within the machine calculates the impedance between the file the machine calculates the impedance between the file tip and lip mucosa; the apex is detected using the tip and lip mucosa; the apex is detected using the calculated impedance via needle pointers, sounds, calculated impedance via needle pointers, sounds, lights, digital reads or various combinations thereof lights, digital reads or various combinations thereof depending on the machine used. depending on the machine used.

ApexlocatorsApexlocators New technology in this area has resulted in New technology in this area has resulted in

microprocessors that measure frequency shifts and microprocessors that measure frequency shifts and apical capacitances. apical capacitances.

As a result, accuracy of these locators has improved, As a result, accuracy of these locators has improved, especially in the presence of anatomical aberrations and especially in the presence of anatomical aberrations and canal moisture. canal moisture.

Examples of these include the Root ZX (J. Morita USA), Examples of these include the Root ZX (J. Morita USA), the Justwo (Medidenta International) and the Endex the Justwo (Medidenta International) and the Endex (Osada Inc.). Some of these use an alternating current of (Osada Inc.). Some of these use an alternating current of at least two frequencies, and measure and compare the at least two frequencies, and measure and compare the two electrical impedances. two electrical impedances.

ApexlocatorsApexlocators This millennium is certain to deliver even more accurate This millennium is certain to deliver even more accurate

apex locatorsapex locators, perhaps even totally eliminating working , perhaps even totally eliminating working length images. length images.

However, even if that goal is never attained, there are However, even if that goal is never attained, there are obvious advantages with the obvious advantages with the third-generation apex third-generation apex locatorslocators available today. These include an accurate available today. These include an accurate working length determination, thereby reducing overall working length determination, thereby reducing overall radiation exposure, as only a minimal number of images radiation exposure, as only a minimal number of images would be required. With accurate readings, there may be would be required. With accurate readings, there may be less chance for over- or underinstrumentation. Also, less chance for over- or underinstrumentation. Also, patient treatment time would be reduced as the result of patient treatment time would be reduced as the result of the speed at which a length can be determined or the speed at which a length can be determined or verified. verified.

ApexlocatorsApexlocators

Root Canals not suitable for Electronic Measurement Reading (EMR)

Root Canal with a large apical foramenRoot canal that has an exceptionally large apical foramen due to a lesion or incomplete development cannot be accurately measured; the results will show shorter measurement than the actual length.

Root Canal with blood, saliva or a chemical solution overflowing from the openingIf blood, saliva, or a chemical solution overflow from the opening of the root canal and contacts the gums, this will result in electrical leakage and an accurate measurement cannot be obtained. Wait for bleeding to stop completely. Clean the inside and opening of the canal thoroughly to get rid of all blood, salivaand chemical solutions and then make a measurement.

Broken crownIf the crown is broken and a section of the gingival tissue intrudes into the cavity surrounding the canal opening, contactbetween the gingival tissue and the file will result in electrical leakage and an accurate measurement cannot be obtained. In this case, build up the tooth with a suitable material to insulate the gingival tissue.

Fractured toothLeakage through a branch canalFractured tooth will cause electrical leakage and an accurate measurement cannot be obtained.A branch canal will also cause electrical leakage.

Re-treatment of a root filled with gutta-perchaThe gutta percha must be completely removed to eliminate its insulating effect. After removing the gutta percha, pass a small file all the way through the apical foramen and then put a littlesaline in the canal but do not let it overflow the canal opening.

Crown or metal prosthesis touching gingival tissueAccurate measurement cannot be obtained if the file touches a metal prosthesis that is touching gingival tissue. In this case, widen the opening at the top of the crown so that the file will nottouch the metal prosthesis before taking a measurement.

Cutting debris on toothPulp inside canalThoroughly remove all cutting debris on the tooth.Thoroughly remove all the pulp inside the canal; otherwise an accurate measurement cannot be made.

Caries touching the gumsIn this case, electrical leakage through the caries infected area to the gums will made it impossible to make an accuratemeasurement.

Extremely dry canalIf the canal is extremely dry, the meter may not move until it is quite close to the apex. In this case, try moistening the canalwith oxydol or saline.

Blocked CanalThe meter will not move if the canal is blocked.Open the canal all the way to the apical constriction to measure it.

Retreatment in endodonticsRetreatment in endodontics Retreatment in endodontics provides a second chance for

the patient to save the tooth that would otherwise be deemed for extraction.

Treatment approach can be either surgical or non surgical. Treatment failure can be due to many reasons from missed canal to iatrogenic perforation which has to be evaluated carefully before initiating the treatment. Sometimes a clinician also has to deal with inter appointment fl are ups requiring prompt and effi cient patient management. This case report describes the non surgical management of failed root fi lled teeth which had also been treated surgically.

Conventional endodontic treatment may fail due to various reasons and inadequate root canal treatment with persistent infection remaining in inaccessible areas of the canal being one of them

Fig 1: Clinical photo of the patient showing draining sinus

Fig 2: Preoperative IOPARadiograph

Fig 3: After Gutta percha removal

Fig 4: Immediate post obturation

Fig 5: 12 months recall Fig 6: 24 months recall (decrease insize of periapical lesion is evident)

If root fi lled tooth has failed, there can be fi ve possible treatment options: To review or do nothing, root canal retreatment, root end surgery, extraction followed by implant or referral. Cross sectional studies from different countries including most recent studies clearly demonstrate that more than 30% of all root fi lled teeth in the population are associated with apical periodontitis or post treatment disease9,10,11,12. A general guideline has been given by European Society of Endodontology13 for indications of retreatment, they are; • Teeth with inadequate root canal fi lling with radiological fi ndings and/or symptoms

• Teeth with inadequate root canal fi lling when the coronal restoration requires replacement

• Teeth with coronal dental tissue that is to be bleached

Conclusion There is enough potential for success of primary

root canal fi lling but fact remains that clinicians are confronted with post treatment disease. Endodontic retreatment could be a suitable option in case of a post treatment disease following an endodontic failure.

Nonsurgical procedures could look of minor importance or insignifi cant during retreatment, for managing surgical endodontic failure especially when reendodontic surgery appears inevitable. However, with non surgical treatment approach and adequate apical and coronal sealing we can achieve favourable clinical outcome even in case of failed surgically treated teeth.