Rhodes’ Referrals – Case 2 October 2013 A case of a · Rhodes’ Referrals – Case 2 October 2013 A case of a missed canal M ANDIBULAR fi rst molars are probably the most common

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John RhodesBDS, FDS RCS, MSc, MFGDP, MRD RCSis a Specialist in Endodontics and owner of The Endodontic Practice in Poole, Dorset

October 2013Rhodes’ Referrals – Case 2

A case of a missed canalMANDIBULAR fi rst molars

are probably the most common teeth to be

referred for specialist endodonti c treatment. They can be notoriously challenging to anaestheti se when the operator is faced with a hot pulp and the mesial canals, which are invariably curved in two planes, can prove diffi cult to instrument successfully. Either way, inability to remove infected or infl amed material can lead to persistent

problems for the pati ent.A 49-year-old man was referred for

assessment of his mandibular left fi rst molar tooth (36). The tooth had been root-fi lled by his general denti st aft er becoming pulpiti c.

On presentati on the tooth was uncomfortable and ached for a period of a few hours every day. There had been several painful episodes since the root fi lling was completed. Interesti ngly the pati ent reported an occasional reacti on to

heat immediately following root treatment, but this had subsided.

A temporary composite restorati on had been placed, which appeared to be providing adequate coronal seal, and longer term the tooth could be reliably restored with a cusp-coverage restorati on. There was no buccal swelling nor sinus tracts but the tooth was tender when biti ng on a tooth slooth.

Periodontal probing revealed no bleeding or pocketi ng and microscopic assessment showed no evidence of microcracking. The adjacent teeth were minimally restored and responded positi vely to sensibility testi ng.

Radiographic assessment showed root fi lling material in three canals. The mesial canals had been well tapered and obturated. Filling material in the distal canal was short of the apex but the root canal apical to this was not visible. A second unprepared root canal appeared to be present, and apically the periodontal ligament was widened (Figure 1).

A diagnosis of failed root canal treatment and missed canal was made with early signs of periapical periodonti ti s.

Sensible treatment opti ons therefore include:• Non-surgical re-treatment followed by restorati on with cusp- coverage • Extracti on and replacement with an implant or adhesive bridge Extracti on and replacement with an implant should be feasible, but the tooth was defi nitely restorable and a good root fi lling complemented with a well-fi tti ng crown could be expected to functi on as well as an implant-supported crown, for

signifi cantly less cost and surgery ti me1. Root end surgery would be inappropriate as the root fi lling was not technically good2.

Non-surgical re-treatment gives an opportunity to disinfect the root canal system in its enti rety. The technical challenge in this case is removal of condensed gutt a percha as well as locati ng and re-negoti ati ng the root canals in the distal root.

Non-surgical disassemblyand re-treatmentTo digress briefl y, good and profound local anaesthesia is the key to delivering pain-free endodonti cs in pulpiti s cases. For a hot mandibular molar, use two ID blocks (perhaps with Arti caine and Mepivicane) combined with a buccal infi ltrati on of Arti caine and adjuncti ve intraligamental or intraosseous infi ltrati on. Allow fi ve to 10 minutes before att acking the pulp, and if things are sti ll hot, resort to intrapulpal infi ltrati on.

Fortunately there was unlikely to be any signifi cant vital pulp remaining in this parti cular case!

Aft er rubber dam applicati on (Figure 2) and using an operati ng microscope, an access cavity was made through the composite restorati on with a long tapered diamond bur.

Examinati on of the pulp fl oor revealed fi lling material in the

Figure 1. Pre-operati ve radiograph

Figure 2. Rubber dam isolati on, in this case using a plasti c clamp

Figure 3. The pulp fl oor with obturati ng material in three canals Figure 4. The distal canals prepared and isthmus cleaned

CPD

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October 2013

distobuccal canal and the orifice of the disto-lingual canal; the two joined by an isthmus. This highlights the importance of good illumination and magnification in endodontics and is why endodontic specialists use an operating microscope.

Interestingly the canal does not appear sclerosed as the radiograph would suggest and this is not an uncommon finding when breaching the pulp of radiographically “sclerosed” cases – you don’t always know until you are in there (Figure 3).

The bulk of gutta percha was removed using Gates Glidden burs sizes 2 and 3 with a Hedstrom file to recover any tags. A few drops of chloroform were introduced into the canals so that any remaining gutta percha was softened and the working length estimated with an apex locator.

Preparation was completed and refined with Wave.One primary and large instruments, always working through a puddle of sodium hypochlorite in the access and irrigating frequently.

At this point the canals were dried with matched paper points and a small drop of chloroform introduced. This is important as gutta percha can be forced into lateral anatomy such as an isthmus or fin even during poor condensation and should be removed before disinfecting (Figure 4).

The irrigation phase comprised using 3% sodium hypochlorite, activated with passive ultrasonic irrigation in 20-second bursts over a total time of about 30 minutes. Smear layer was removed with 20% citric acid. The ultrasonic tip was manipulated through the isthmus.

Finally, the case was obturated using a vertically compacted gutta percha technique (Figure 5) and the access sealed with IRM and compomer.

A final radiograph showed the completed re-treatment (Figure 6).

References1. Torabinejad M, Anderson P, Bader J et al. Outcomes of root canal treatment and restoration, implant-supported single crowns, fixed partial dentures and extraction without replacement: a systematic review. J. Prosthet

Dent 2007; 98(4): 285-3112. Guidelines for surgical endodontics: http://www.rcseng.ac.uk/fds

Figure 5. Obturating material sealing the distal canals and isthmus

Figure 6. Post-operative radiograph

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