METHODS
The clinician informed the patient of the diagnosis and recommended root canal treatment. After obtaining consent, local anesthesia was administered using 1.8 ml of 2% lidocaine with 1:100,000 epinephrine. A rubber dam was placed to ensure isolation of the operative field. All subsequent procedures were performed under magnification using loupes. The existing restoration was removed, the endodontic access cavity was refined, and a pre-endodontic buildup was completed using composite.
During the clinical examination, four root canals were initially identified: mesiobuccal (MB), mesiobuccal 2 (MB2), distobuccal (DB), and palatal (P). Under magnification and with the aid of a DG 16 endodontic explorer (Hu-Friedy), two small hemorrhagic pinpoints were detected in the grooves extending from the MB to P and DB to P directions. Further exploration led to the identification of additional canals, namely MB3 and DB2, which were successfully negotiated using a #8 K-file (MANI, Dentsply) (Fig. 1b).
The initial access design for the canals was triangular but was modified to enhance accessibility to the additional canals. An electronic apex locator (AirPex, Eighteeth, Changzhou Sifary Medical Technology, China) was used to determine the working lengths of all six canals, and the measurements were confirmed with a digital radiograph (Fig. 2a). The first distobuccal canal was found to merge with the second distobuccal canal in the middle third, continuing as a single canal.
Digital radiovisiographs (Kodak RVG system) taken at a 20-degree angle revealed the convergence of the MB1 and MB2 canals in the apical third (Fig. 2b). Initial instrumentation of the canals was performed using #15 stainless steel K-files (Mani Inc, Tochigi, Japan) with 5% sodium hypochlorite (Septodont, Saint-Maur-des-Fossés, France) as the irrigant. The canals were then cleaned and shaped using Protaper rotary nickel-titanium files (Dentsply Maillefer) with a crown-down technique. To promote healing, calcium hydroxide (Prime Dental Products, Thane) was placed as an intracanal medicament, and the access cavity was temporarily sealed with Cavit-Temp (Ammdent, Mohali, Punjab).
After one week, the tooth was asymptomatic. The final obturation was completed using Bioceramic sealer (SafeEndo, Vadodara, India) and Guttapercha (Dentsply Maillefer) (Fig. 3a, 3b). Post-obturation radiographs were taken to confirm the successful completion of the procedure (Fig. 4a, 4b). Two weeks after obturation, prosthetic rehabilitation was carried out with a zirconia crown (Fig. 5a, 5b). At the six-month follow-up, the patient remained asymptomatic, and radiographs showed evidence of periapical healing (Fig. 5c).