A 42-year-old Caucasian male was referred by his general dental practitioner for endodontic treatment of his mandibular left second molar (tooth 37). On Christmas Day in 1999, the patient had severe pain from tooth 37. The referring dental practitioner initiated root canal treatment but encountered curved root canal anatomy. Treatment was discontinued, calc um hydroxide dressings were placed in the root canals and a referral to the dental hospital was made. The patient had suffered one episode of pain after the initial treatment, which was treated with antibiotics.

Clinical examination

The patient had good oral hygiene. The general periodontal status was good with normal probing profiles. The dentition was moderately restored. In the intercuspal position, the molar relationships were Class I on both sides with multiple contacts
between the upper and lower posterior teeth. The anterior teeth showed normal overbite and overjet.

In the retruded contact position (RCP), the first contacts were between teeth 17 and 46 on the right side and teeth 27 and 37 on the left side. The slide from the RCP to ICP was straightforward with large horizontal and small vertical components. The
condylar movement was mainly translation.

On protrusion, the incisors provided the guidance while canines guided lateral excursions on both sides. No excursive interferences were detected on either side.

Clinical examination of tooth 37 revealed the presence of a temporary restoration. The tooth was mildly tender to percussion and biting. No sinus tract was evident and periodontal probing depths around tooth 37 were within normal limits. Tooth 37 was
observed to have tipped mesio-angularly.

Radiographic examination

A dental panoramic tomograph (DPT) showed a moderately restored dentition with healthy levels of alveolar bone. The DPT also showed an area of radiolucency associated with the distal root of tooth 37. Concurring with the DPT, a periapical radiograph
of tooth 37 revealed the presence of periapical radiolucency in the distal root area. The root canals of tooth 37 were unfilled.

Provisional diagnosis

The toothache experienced by the patient from tooth 37 on Christmas Day was an acute exacerbation of chronic apical periodontitis associated with the tooth.

Treatment plan

Two treatment options for tooth 37 were discussed with the patient. One was to root treat and then upright the tooth orthodontically for placement of a cast gold restoration. The other was to extract it. The patient was motivated to pursue the best longterm treatment outcome for his molar tooth. After understanding the duration of treatment, compliance and prognoses of the various treatment strategies, he elected for root canal treatment of tooth 37 and its subsequent orthodontic and restorative treatment.

Treatment

a. Root canal treatment of Tooth 37
Anaesthesia of tooth 37 was achieved with a local infiltration of 2% lidocaine with 1:80,000 epinephrine.
Tooth 37 was isolated by rubber dam and its temporary restoration removed. An orthodontic band was fitted and cemented onto tooth 37 with Ketac-Fil Plus before endodontic treatment was commenced.

Three canal orifices were identified. The apical parts of the canals and their foramina were explored with size 6 K-Flex files. All the canals appeared to exit distolingually. In particular, that of the distal canal did so at a rather acute angle. The root canals were pre-flared with small size Heström files. Root ZX apex locator zero readings, verified by periapical radiographs, were obtained in all three canals. The working lengths for these canals were established at 0.5mm short of the zero reading lengths.

At the following visit, the canals were prepared to an apical size of 25 using Flexofile and Flexofile Golden Mediums in a watch-winding motion. The taper of the canal was prepared by 0.5mm step-back increments up to size 60. Copious 2.5% sodium hypochlorite irrigation was used and canal patency was maintained with size 10 K-Flex files. Calcium hydroxide, as an intra-canal medicament, was used and the access cavity was sealed with cotton wool pellet and IRM.

The canals were subsequently obturated with gutta percha and Roth sealer using a formed cone technique, cold lateral condensation and Piezon ultrasonic energised spreading. The coronal 3mm of gutta percha was removed from the canals and the access cavity restored with an amalgam Nayyar core.

b. Orthodontic uprighting of tooth 37
For the next phase of the treatment, the patient was referred to the orthodontic department for uprighting of the tooth 37. A compressed coil spring on a round wire (18 mil steel) was used to upright the tooth. This was completed in nine months. The uprighting yielded a greater than expected separation of the molars. It was decided that the excess space would be managed
during the restorative phase using a deliberately under-contoured temporary crown. This allowed a controlled mesial drift and tipping of tooth 37, which eventually eliminated the excess space. The extra space was closed in two months.

c. Diagnostic occlusal adjustment
As there was RCP contact between tooth 37 and its opposing tooth (tooth 27), crown preparation on tooth 37 would eliminate this contact. This may have resulted in an adaptive response that led to a new condylar position, as well as a different path of
closure. This is because without the deflective RCP contact, the mandible could close slightly distally to the original ICP. This can reduce interocclusal space, such that when the crown is fitted it may be found to be ‘high’.

One solution to this potential problem is to eliminate the RCP to ICP slide altogether and restore tooth 37 to RCP. However, to eliminate the slide would require removal of tooth structure. Diagnostic occlusal adjustment on study models was carried out
to assess the amount of tooth tissue that needed to be removed.

The occlusal surfaces of the study models, which were mounted in the RCP, were painted with a layer of blue die relief agent. Occlusal contacts were marked with articulating papers and removed with a scalpel blade. This process was repeated until the RCP became coincident with the ICP.

By inspecting the lower model, it was apparent that tooth tissue would need to be removed from the mandibular right first and second molars, mandibular right first premolar, mandibular left first molar and tooth 37 to make the RCP coincident with the ICP. The amount of tooth tissue removal required was considered unjustifiable. Instead, it was decided that tooth 37 would be restored to ICP, ensuring accurate registration of the ICP, and occlusal adjustment would be made during the fitting of the crown.

d. Preparation of tooth 37 for a gold onlay
After removal of the orthodontic brackets and coil spring, tooth 37 and its amalgam core were prepared to receive an MOD gold onlay. An impression was taken at a subsequent visit. Meanwhile, tooth 37 was temporised with a mesio-proximally under-contoured
provisional crown, which allowed controlled mesial drifting and/or tipping of tooth 37 to close the extra interproximal space.

e. Laboratory procedures
Except for the casting process, the author carried out was seated and inspected for marginal fit, interproximal and occlusal contacts. Once all of these aspects were considered satisfactory, the crown was cemented with zinc phosphate cement.

g. Review
The patient was symptom-free when reviewed at 12 months post-operatively. Although not taken in exactly the same view, comparison of pre-operative and review periapical radiographs showed an increase in bone density around the periapex of the distal root
area of tooth 37.

Discussion

Root treated teeth can be moved as readily and for the same distance as vital teeth (Huettner RJ, Young RW, 1955; Wickwire et al, 1974; Mattison et al, 1983; Hunter et al, 1990; Mah et al, 1996). However, some authors have recommended that for teeth requiring
root canal and orthodontic treatment, the cleaning and shaping of the canals should be carried out first, followed by an interim dressing of calcium hydroxide (Andreasen JO, Andreasen FM, 1994). Canal obturation is only completed after orthodontic treatment. This approach stems from concern that apical resorption, which can occur during orthodontic treatment, may challenge the apical seal.

A root canal treatment case study: A 57-year-old female was referred by her general dental practitioner for intermittent pain, local swelling and suppuration in the region of the maxillary left first molar (tooth 26). About four years earlier tooth 26 developed non-specific symptoms, which were managed by local periodontal treatment. Following that, the patient continued to experience intermittent mild discomfort during which the affected site would be treated with subgingival scaling and root planing.

Then two years ago, the conditions deteriorated with pain, swelling and discharge of pus from the adjacent mucosa of tooth 26. In particular, the gingiva around the mesiobuccal root of tooth 26 was inflamed and showed a gingival recession of 5mm. Periodontal probing revealed pocket depths of 10mm in the buccal area of the mesio-buccal root.

However, apart from areas around tooth 26, the general periodontal status was normal. Tooth 26 did not respond to pulp vitality tests and was tender to percussion.

A provisional diagnosis of an endo-perio lesion associated with tooth 26 was made. The treatment plan was first to root treat the tooth, followed by periodontal treatment. Root canal treatment of tooth 26 was duly completed. However, the pus discharge from the area continued unabated.

Clinical examination

The patient was healthy. Apart from hormone replacement therapy, she was not on any medication. The patient had regularly attended the dentist every six months.

The patient had good oral hygiene. Apart from tooth 26, the periodontal probing profile of

Figure 1: Examination of the problem site

the remaining teeth was within normal range. In the intercuspal position (ICP), the molar relationships were class I on both sides. The anterior teeth showed normal overjet and overbite. At the retruded contact position (RCP), the initial contacts were between tooth 17 and tooth 47 on the right side.

The incisors provided the anterior guidance. There was immediate posterior disclusion on protrusion of the mandible. Lateral excursions saw multiple contacts between teeth on the working sides (group function). No non-working side interference was present on either side.

Tooth 26 was restored with a class I amalgam restoration. The tooth was mildly tender to percussion and biting. Its adjacent mucosa was swollen and exuded pus on palpation (Figure 1). Periodontal probing revealed a 10mm periodontal pocket in the buccal aspect of the mesiobuccal root.

Radiographic examination

Figure 2: Moderately restored dentition with generally good alveolar bone support

A dental panoramic tomograph (DPT) (Figure 2) showed a moderately restored dentition with generally good alveolar bone support. Consistent with the DPT, a periapical radiograph of tooth 26 revealed extensive periradicular bone loss in the mesiobuccal root area. A comparison radiograph taken 12 months earlier had shown progression of the bone loss (Figures 3 and 4).

Figure 3: Preoperative radiograph.

Figure 4: Preoperative tooth 26 after initial RCT

A periapical radiograph of tooth 26 showed three rootfilled canals. The root canal fillings appeared not to be well condensed and those in the mesio- and distobuccal roots were short of their respective radiographic apices. Apical extrusion of gutta percha from the palatal root was evident (Figure 4).

Provisional diagnosis

The localized periodontal defect in a patient with otherwise healthy periodontium and the failure of previous periodontal therapy were suggestive of an endo-perio lesion.

Root Canal Treatment

a. Root canal retreatment of tooth 26

Figure 5: Master apical files

Local anesthetic was administered by local infiltration using 2.2ml 2% lignocaine with 1:80,000 adrenalin. Rubber dam was placed to isolate tooth 26. The existing class I amalgam restoration was removed and endodontic treatment was commenced. The gutta percha in the canals was softened with chloroform and removed with Hedstroem files. The second mesiobuccal canal was also located. All the canals were irrigated copiously with 3% sodium hypochlorite and Betadine. Coronal flaring with Profile orifice shapers was
carried out and patency was gained for all canals. The tooth was dressed with calcium hydroxide and access was sealed with cotton wool and IRM.

Figure 6: Retreatment completed

At the following visit, the working lengths were determined with the use of a Root ZX apex locator and periapical radiographs. Using Flexofile and Flexofile Golden Mediums, the canals were apically enlarged to size 35 for the palatal canal and size 30 for the other canals (Figure 5). The step-back increment was 0.5mm for all canals. The root canal system was obturated with gutta percha and Roth sealer using a formed cone technique and cold lateral condensation. Energized spreading completed the final obturation. The access cavity was restored with an amalgam Nayyar core (Figure 6).

At the six-month review, the patient reported that the exudation from the periodontal pocket of tooth
26 had persisted.

The adjacent mucosa of the mesiobuccal root still exuded pus on palpation.

Periodontal probing revealed a deep periodontal pocket associated with the buccal aspect of the mesiobuccal root. It was decided to proceed with root resection of the affected mesiobuccal root. Root resection was confined to just the mesiobuccal root because of the normal probing depths around the rest of the tooth and normal radiographic appearance of the interradicular bony region.

Figure 7: Tooth 26 preoperative	Figure 8: Pus discharge
Figure 9: Reflection of mucoperiosteal flap	Figure 10: Separation of mesiobuccal root
Figure 11: Extraction of mesiobuccal root	Figure 12: Odontoplasty and retrograde amalgam
Figure 13: Postsurgical results at one week	Figure 14: Postsurgical results at two months
Figure 15: Satisfactory access for plaque control

b. Mesiobuccal root resection of the tooth 26

(Figures 7 to 15)

On the day of the surgery, the surgical site was anesthetized by buccal and palatal infiltrations of 2%
lignocaine with 1:80,000 adrenalin local anesthetic solution. Buccal mucoperiosteal flaps were raised by intra-sucular incisions from the mesial aspect of tooth 24 to the mesial aspect of tooth 27.

The mesiobuccal root was immediately visible when the flap was elevated (Figure 9). The root was resected apical to where it joined the crown (Figure 10 and Figure 11). The root stump was smoothed down with a white stone. The tooth trunk was reshaped by odontoplasty, creating an area that would be easy to clean (Figure 12). All remaining granulation tissues were curetted.

The flap was replaced and firm pressure applied using a moist gauze pack to minimize blood clot formation beneath the flap and allow better approximation of the flap to the bone. Four sutures (Ethilon 5/0) were placed to secure the flap. Firm pressure was reapplied and postoperative instructions given. Healing was uneventful. One week after the surgery, the patient returned asymptomatic for suture removal (Figure 13).

c. Review

At the two-month review there were no symptoms and the patient was free of complaints. Tooth 26 showed a Grade 0–I tooth mobility. Its adjacent soft tissue had healed satisfactorily (Figure 14). Periodontal probing depths around the tooth were within normal range. Accessibility of the resected root area for plaque control was good (Figure 15).

At the 24-month review, the tooth remained symptom-free. Radiographic examination showed a clean surgical site (Figure 16a-c).

Figure 16a: Initial review radiograph

Figure 16b: Review radiograph at one week

Figure 16c: Review radiograph after two years.

Discussion

In the reported case, the origin of the endo-perio lesion associated with tooth 26 was unknown. Establishing the original cause of an endo-perio lesion is not usually straightforward. Serial radiographs and the state of the pulp on first entering the root canal system can provide useful clues. For example, the presence of a vital (bleeding) pulp in a tooth associated with serial radiographs, which showed
progressive periodontal disease, would suggest a periodontal origin to the endo-perio lesion. Unfortunately, in this case this information was lacking. Serial radiographs of tooth 26
were not available and the general dental practitioner who carried out the primary root canal treatment had not recorded the state of the pulp on entering the pulp chamber.

The discharge of pus from the periodontal pocket of tooth 26 had persisted despite the root canal retreatment. This may have been a result of persistent periodontal disease, intracanal microorganisms that were inaccessible to instrumentation (Sundqvist et al 1998) or coronal leakage (Ray & Trope, 1995). The severe bone loss affecting the mesiobuccal root and the previously unsuccessful periodontal and endodontic therapies led to root resection of the affected root as the next treatment option.

A study of the literature indicated a divergence of opinion on the effectiveness of root resection therapy. The differing success rates from one study to another are a result of a lack of consensus in the criteria used to evaluate treatment outcome. While a few authors had used strict periodontal criteria such as bleeding index, pocket depth or attachment loss, most used tooth survival as the only evaluation criterion
to measure long-term results. The reasons for root resection, how the teeth were subsequently restored and the operator’s skills were also different in each case. An accurate comparison and summary of data is therefore difficult to achieve.

Despite these limitations, some trends can be identified. The failure rates of root resection procedures after five years, as reported by most studies, are low. In a limited metaanalysis using common denominators of time of observation and criteria of failure as defined by Langer et al (1975), Buhler (1988) reported that the failure rate for teeth treated by root resection, over a seven-year observation period, was 11%.
With guarded optimism, the prospect of tooth 26 healing after root resection was assessed to be good.

References

Buhler H (1988) Evaluation of root-resected teeth. Results
after 10 years. Journal of Periodontology 14: 537-543

Langer B, Stein SD, Wagenberg B (1975) An evaluation of
root resections: A 10-year study. Journal of Periodontology
46: 1-5

Ray HA, Trope M (1995) Periapical status of
endodontically-treated teeth in relation to technical quality
of the root filling and the coronal restoration. International
Endodontics Journal 28: 12-18

Sundqvist G, Figdor, Persson S, Sjogren U (1998)
Microbiological analysis of teeth with failed endodontic
treatment and the outcome of conservative re-treatment.
Oral Surgery, Oral Medicine, Oral Pathology, Oral Radiology
and Endodontics 85: 86-93

More links : What is Endodontics (Root Canal Treatment)

Roots Advanced Endodontics is a dental clinic in Singapore that specialises in treating severe toothache and root canal diseases (endodontics). Located on the top floor of the Novena Medical Center @ Square 2, our clinic focuses on providing competent root canal care. In particular, a comfortable root canal treatment experience for our patients.