International Endodontic Journal (\9%) 19, 107-112

Surgical endodontic retreatment

C. REIT & J. HIRSCH* Department of Endodontics, Faculty of Odontology, University ofGoteborg, and *Department of Oral Surgery, Public Dental Service, City ofGoteborg, Sweden

Summary. In teeth with periapical lesions anddefective root canal seals non-surgical retreatmentis usually preferred. Sometimes, however, suchtreatment may not be feasible and periapicalsurgery must be performed. The present studyinvestigated a technique of retrograde root canaltreatment as an alternative to the more conven-tional types of surgical procedure. The materialconsisted of 35 teeth whose root canals containedposts. In 77 per cent of the cases it was possible toinstrument and obturate the root canal up to thepost. Following treatment the periapical tissues, asevaluated clinically and radiographically, showedevidence of having healed in 71 per cent of cases.

IntroductionThe basic objective of endodontic treatmentis to clean and obturate the root canalspace. However, treatment procedures do notinvariably produce the desired healing, Peri-apical lesions, sometimes in conjunctionwith clinical symptoms, may persist ordevelop. The frequent association of peri-apical lesions with defective obturation ofroot canals has been demonstrated in severalstudies (Strindberg 1956, Engstrom 1964,Kerekes & Tronstad 1979), In such cases ithas been recommended that the root canalshould be retreated non-surgically, in orderto clean the canal and improve the seal(e,g, Bergenholtz et al. 1979), Sometimesnon-surgical retreatment may not be feasible,for example, when the root canal contains apost which is very difficult or impossible toremove; in this situation surgical retreatmentis an appropriate alternative.

A method designed to improve the tech-nical quality of the seal during peri-apical surgery has been described byNygaard-Ostby (1971), He suggested a pro-Correspondence; Claes Reit, Department ofEndodontics, Faculty of Odontology, Universityof Goteborg, Box 33070, S-400 33 Goteborg,Sweden,

cedure where the root canal was debrided,shaped and obturated from the apical end andin a coronal direction. This 'retrograde rootcanal treatment' was designed to produce theoptimal possibility of removing irritatingmaterial still present in the canal, and to pro-duce a satisfactory seal. Since no reports havebeen published on the subject, the aim of thepresent study was to investigate the technicalaspects of the proposed method, and toconduct a primary evaluation of resultanthealing.

Materials and methodsThe treatment sample was selected frompatients referred to the Department ofEndodontics, University of Goteborg, andthe Department of Oral Surgery, Public Den-tal Service, City of Goteborg, Thirty-fiveteeth in 33 patients were chosen for treatment(Fig. 1). Their ages ranged 26-67 years (mean54 years). The consecutively selected cases allhad radiographic signs of periapical disease.In eight of the cases, clinical symptoms suchas pain, tenderness or swelling, were alsopresent. The root canals in each case hadreceived previous endodontic treatmentwhich was evaluated as technically un-satisfactory. Representative cases are shownin Fig. 2, Non-surgical endodontic retreat-ment was considered impossible or undesir-able in all instances because of the presence ofposts within canals.

Surgical procedureAfter injection of a local anaesthetic a buccalmarginal mucoperiostal flap was raised. Theapical parts of the roots were exposed by boneremoval with burs when necessary. Theapices were resected in cases with apicalcalcification. The root canals were cleanedand shaped with Hedstrom files held in a

107

108 a. Retl 6J. Hirsch

10

nk- O

c -^QJ CJ

Fig. 1. Distribution of cases according to toothtype. Unfilled parts of bars denote maxillary teethand filled parts mandibular teeth.

hacmostat. Sodium hypochlorite (0.5 percent) in a 5 ml single-use syringe' was used asan intra-canal irrigant. An attempt wasalways made to instrument the root canal upto the apical part of the post. Obturation ofthe root canal system was carried out with alateral condensation technique using chloro-form-softcncd gutta-percha.~ The technicalprocedures are further described in Fig. 3.The surgical area was then carefully irrigatedwith sterile saline solution and the flap wasreplaced and sutured.

Evaluation of resultsPatients automatically became participants inthe recall system of the Department off^ndodontics, which implies that a case isusually examined every other year, until it isclassified either as healed or as a failure. Inthe present study patients were recalled forfinal clinical and radiographic evaluationduring 1984. At these recall examinationstwo radiographs were taken from slightly

'Onee®, ASIK, Denmark.^Ordinary gutta-percha points, DeTrey AG,Ziirich, Switzerland.

different angles using the method describedby Eggen (1969). The radiographs wereevaluated simultaneously by the two authors.Films were examined under moderate illumi-nation at a light table and with the aidof a magnifying viewer equipped with amasking frame, which was the size of a dentalfilm.

During evaluation of radiographs the maxi-mum working length (the distance from theroot apex to the apical end of the post) andthe length of any observed space betw een thecoronal end of the root canal filling and thepost was measured (Fig. 3). Pre-surgicalradiographs and final recall radiographs werecompared and the bone lesions were classifiedas larger, unchanged, smaller or healed. Thecriteria used for classifying a case as healedwere those of Rud et al. (1972): 'A laminadura is to be followed around the apex. Thewidth of the periodontal space in the apicalregion may be widened to as much as twicethe normal around non-involved parts of theroot. A tiny defect in the lamina dura adjacentto the root filling is tolerated (maximum1 mm"̂ ). The bone cavity should be filled inwith bone although this may not have thesame radio-opacity and structure as thenon-involved bone' (Fig. 2).

ResultsThe technical results obtained with retro-grade root canal treatment are shown inTable I. In 27 of the 35 cases (77 per cent) itwas possible to shape and obturate the rootcanal to within 0.5 mm of the post. Theremaining roots were all negotiable withHedstrom files, but to a shorter extent; inmost of these latter cases this was due toinability to remove the coronal portions of theold root canal filling material or the cementsurrounding the post. In all eases theinstrumented part of the root canal wasadequately filled with gutta-percha, i.e. nospace was discernible between the root canalwalls and the filling material, as judgedradiographically.

At the final recall examination 25 of thecases were classified as healed (71 per cent),eight of the lesions (23 per cent) were reducedin size, and one was regarded as unchanged(Table II). Canals obturated to within

Surgical endodontic retreatment 109

Fig. 2. (a) A 67-year-old woman presenting with acute apical periodontitis of the right maxillary canine. Atthe final recall examination, 6 years after surgery, the periapical tissues were classified as healed, (b) A67-year-old woman with chronic apical periodontitis of a maxillary second premolar. This was classified ashealed at the final 4-year recall, (c) A lateral incisor with chronic apical periodontitis in a 55-year-old woman.This patient developed a post surgical abscess. At the final recall, after 7 years, the periapical lesion wasjudged to be reduced in size.

no C. Reit (SJ. Htrsch

Table 1. Technical results of retrograde root canalfilling. Distribution of cases according to workinglength and unobturated distance between rootcanal filling and post

Maximumworking length(mm)

<5

>5

Unfilled

^0.5

10

17

space (mm)

>0.5

2

6

(c) (d)

Fig. 3. Intracanal treatment procedures, (a)Instrumentation begins with a cut-ofF Hedstromfile (ISO size 20) held in a haemostat. Using a flarepreparation technique the root canal is enlarged toISO size W~50. Sodium hypochlorite (0.5 percent) is used as an irrigant. (b) A gutta-perchamaster point is selected, (large, long gutta-perchapoints') fitting 2 mm short of the coronal end ofcanal, which has been dried with absorbent paperpoints, (c) The master point is softened in chloro-form and pushed slowly up to the coronal end ofthe root canal. Lateral condensation is carried outwith the use of an angled gutta-percha spreader.^Additional points are softened in chloroform andinserted into the canal. Excessive root fillingmaterial is removed by a heated excavator, (d)Maximum working length (I) and the spacebetween the root canal filling and the post (II) aremeasured on the radiograph.

0.5 mm of the post showed complete periapi-cal healing in 21 cases (78 per cent). Of eightroot canals obturated at a distance greaterthan 0.5 mm from the post, four showed com-plete healing (50 per cent).

'DeTrey AG, Zurich, Switzerland."Gutta-percha spreader no. 3, Kerr Sybron,Romulus, Michigan, USA.

Only one of the patients developed clinicalsigns of periapical disease. In this casea draining sinus tract was noticed 4 yearsafter surgery. Abscesses as immediate post-surgical complications were found in twopatients.

DiscussionThe development or persistence of a periapi-cal radiolucency following endodontic treat-ment is often regarded as a criterion offailure. Endodontic failures are most fre-quently associated with defective root canalobturation (Strindberg 1956, Bergenholtz etal. 1973) and the presence of bacteria in theroot canal system (Sundqvist 1976, Fabricius1982). Hence, retreatment had been proposedin such cases. For the clinician faced with achoice between non-surgical and surgicalprocedures the literature on prognosis is con-fusing. For non-surgical endodontic retreat-ment the reported frequency of successfulcases varies between 60 per cent and 80 percent (Molven 1974, Bergenholtz et al. 1979).However, such studies are rare. The successrate of surgical treatment has been discussedby many authors and is reported to varybetween 30 per cent and 65 per cent, depend-ing on variations in material, method ofoperation and criteria for evaluation ofhealing (e.g. Persson 1966, Mattila &Altonen 1968, Nordenram & Svardstrom1970, Hirsch et al. 1979). However, due to theproblem of defining criteria of periapicalnormalcy and disease, comparisons and con-clusions based on data obtained in radio-graphic recall studies are extremely difficultto make (e.g. Goldman et al. 1972, Reit &

Surgical endodontic retreatment 111

Table IL Comparison of periapical lesions in 35 cases between initial and finalexamination

Follow-upperiod (years) Healed

Smallersize

Unchangedsize

Larger size/symptoms

Totals

333

16

25

HoUender 1983). In any event, consensushas been reached in the literature regardingthe importance of the quality of root canalobturation on the outcome of the treatment.This has led many authors to recommend anon-surgical approach to retreatment of peri-apical lesions in teeth showing defective rootcanal fillings (e.g. Nygaard-Ostby 1971,Bergenholtz et al. 1979). However, such pro-cedures sometimes cannot be done, primarilyfor technical reasons. In these cases the treat-ment method described in the present studyoffers a method to achieve canal debridementand establish an apical seal when non-surgicalretreatment is contra-indicated.

Compared with the conventional surgicalapproach the retrograde shaping of the rootcanals sometimes required a more extensiveremoval of periapical bone. The retrograderoot canal treatment thus seems most appro-priate in regions where the roots are ratherclose to the buccal cortical plate of bone. Oldroot fillings were usually easy to remove, androot canals were instrumented in a coronaldirection as far as possible; the workinglength was established merely on a tactilebasis. A very gentle and careful cleaning ofthe root canal was then carried out in ordernot to contaminate the periapical tissues withintracanal infectious material. During thisprocedure the root canal was flushed withsodium hypochlorite (0.5 per cent), which haspreviously been shown to have a goodantimicrobial effect (Bystrom & Sundqvist1983, Foley et al. 1983) as well as a lowirritant effect on tissues (Spangberg et al.1973, The et al. 1980). However, efforts werealways made to keep the irrigant strictly

within the canal. From a clinical point ofview, shaping of the root canal was con-sidered as complete when a large-sized, longgutta-percha cone with its tip cut off couldeasily be introduced.

Total debridement and obturation werethe objectives of the 'retrograde root canaltreatment' used. This goal was accomplishedin 27 of the 35 cases (77 per cent). Thus, atleast in the anterior region, this methodappears to have considerable potential forremoving intracanal irritants, and improvingobturation in a sizeable area of the root canalsystem. Although the risk of spreadinginfectious material during cleaning of thecanal might be considered high, only two ofthe patients developed postsurgical abscesses.

Using a very strict criterion of periapicalhealing 25 of the 35 treated cases wereclassified as healed (71 per cent). Furtheremphasis on the importance of thoroughlydebriding and obturating the root canal wasthe fact that the healing frequency reached 78per cent when the root canal could be shapedand obturated to within 0.5 mm of the post,compared with 50 per cent when this was notpossible. Because of the small sample size ofcases in this study, the use of statisticalanalysis was not warranted. However, theresults do indicate the potential usefulness ofa surgical approach to endodontic retreat-ment which combines surgical curettage withroot canal debridement and filling. Furtherstudies on the subject would be of value.

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