Location and thorough instrumentation of all the canals in the root of a diseased tooth normally ensure success of the endodontic therapy.  Presented is a case of mandibular second premolar which was referred for endodontic therapy. Clinical and radiographic examination revealed inadequate root canal filling. Three canals were located. Endodontic therapy was performed under aseptic conditions.

Detailed knowledge of root canal anatomy and awareness of the configuration of the pulp canal are essential when practicing root canal therapy. There are evident indications that root canal morphology is almost limitless in its variability. The unusual number of canals should always be expected in various teeth. Untreated root canals may cause failure of the treatment.

Mandibular second premolars are known to have a single canal. The incidence of their having two or three canals was reported to vary from 0 to 34.3%.1-3 Case reports describing four canals in mandibular second premolar have been  occasionally published.4-7 According to El-Deeb8 the mandibular premolars may show wide variation in their root canal anatomy. Thus, the recognition of atypical anatomy is important even though it is not usually encountered.

The purpose of this article was to report a mandibular second premolar with three distinct canals.

Case Report

A 20- year-old Saudi male with noncontributory medical history was referred to the clinics of the Saudi Board in Advanced Restorative at the Faculty of Dentistry, King Abdul Aziz University for evaluation of root canal therapy of a mandibular second premolar. Clinical examination revealed that the tooth responded positively to percussion but not to palpation. Radiographic examination revealed short and inadequate root canal filling (Figure 1).  The tooth was isolated with rubber dam, the old amalgam filling was removed and the access cavity preparation was established. The gutta-percha was removed using Hedstroem file size 15 without solvent. Three canals were located, buccally, lingually and an extra canal in the middle. The working length was checked radiographically (Figure 2). The canals were conventionally instrumented to a # 35K file using crown-down pressureless technique, irrigated with 5.25 percent sodium hypochlorite, dried with sterile paper points and sealed with calcium hydroxide paste‡  The access opening was closed with Cavit.‡‡  The patient returned asymptomatic after 1 week, the tooth was isolated with rubber dam; the canals were instrumented with file #35 and irrigated with sodium hypochlorite to remove all the remnants of the calcium hydroxide, and then dried with paper points.  Master cone was selected and the canals were filled with gutta-percha and AH26 sealer cement‡‡‡ using lateral condensation.  Access opening was sealed with amalgam restoration. Post-operative radiograph was taken to confirm the quality of the filling (Figure 3).  The patient was referred to the prosthetic clinic for crown construction.

Inadequate debridement and/or incomplete obturation of the root canal system were found to be commonest of root canal therapy failures.9  If a canal is originally cleaned but incompletely filled, tissue fluids from the area could cause chronic inflammatory response in the periradicular tissue,10 In this case three canals were identified, where only one was inadequately filled.  Short canal fillings usually offer no serious problem in retreatment. That is why a Hedstrom file was used without solvent. If a canal is inadequately filled, it is generally due to insufficient canal preparation.  In a study of endodontic failures from histology perspective, Seltzer et al.11 reported inflamed or necrotic pulp tissue in teeth in which endodontic therapy had failed. They found tissues in canals that were not instrumented during treatment.

Although the success rate of retreatment of failed therapy is high, it may be lower than that for initial endodontic therapy.12 Nonsurgical retreatment is always preferable and should be attempted before resorting to surgery. The objective of retreatment is to perform endodontic therapy in order to return the treated tooth to function and comfort, and to allow the supporting structures to repair completely. Retreatment of the present case was performed using the crown-down pressureless technique. It has been advocated by Marshall and Pappin13 in which Gates Glidden drills and large size files should first be used in the coronal two thirds of the canal and before smaller files are progressively used from the crown-down until the desired length was reached. This technique has the advantage of enlarging and cleaning the coronal area before proceeding deeply into the apical regions where majority of the infected tissue is removed.13,14 Furthermore, it provides unobstructed access for instruments to follow. This would help minimize post operative discomfort by preventing the inoculation of periradicular tissues with bacteria and necrotic tissue that might be pushed out by hand files.

A thorough knowledge of the pulp space morphology is essential for successful endodontic therapy. This may help to reduce endodontic failure caused by incomplete obturation.  An extra root canal may be detected by careful clinical and radiographic investigation of the floor of the pulp chamber.15 Finally, variations in root canal morphology must be considered before starting any root canal therapy.

‡Calasept, Scania, JS Dental, Ridgefield, CT, USA

‡‡Premier Dental Products, Norristown, PA, USA

Address reprint requests to:

Dr. Saad Al-Nazhan
Division of Endodontics
College of Dentistry, King Saud University
P.O. Box 60169, Riyadh 11545, KSA
Fax:     +966-1-4678548
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