Assessment of the interorifice distance between middle mesial canal and mesiobuccal canal; and middle mesial canal and mesiolingual canal in permanent mandibular first molars in a North-Indian subpopulation: A retrospective cone-beam computed tomography analysis

Aim: Inadequacy to locate middle mesial canal (MMC) in permanent mandibular first molar (PMFM) is one of the most common challenges faced by endodontist (s) and is the major cause for endodontic treatment failure. This study was planned primarily to measure the interorifice distance (IOD) between MMC and mesiobuccal canal (MBC); and MMC and mesiolingual canal (MLC) in the mesial root of PMFM. Secondary objective was to figure out the prevalence and morphology of MMC in North-Indian subpopulation and assess its relation to gender, age, and quadrant of the mandible using cone-beam computed tomography (CBCT) imaging. Also, to detect the presence or absence of Isthmus in the mesial root of PMFM. Methods: One hundred and sixty-two CBCT slices from 81 CBCT volumes collected from Tricity Healthcare Diagnostic Centre, Chandigarh, which caters to patients from most of the north Indian states, were examined in axial, sagittal, and coronal sections. The presence of MMC, isthmus, and the mean IOD between MBC and MMC; and MLC and MMC was measured using linear measurement tools in the axial sections. The morphology of MMC was determined in the coronal section and classified. Results: The mean IOD between the MBC and MMC and MLC and MMC was found to be 1.07 ± 0.095 mm and 0.97 ± 0.206 mm, respectively. Out of 162 PMFM, the overall prevalence of MMC was found to be 7 (4.3%). The most prevalent canal morphology was confluent type. The highest prevalence of MMC was seen between 31 and 50 years of age. No statistically significant association was found between the gender of the participants and between the side/quadrant of the mandibular arch and the presence of MMC. The overall prevalence of isthmus in the mesial root was found to be 10 (6.2%). Conclusion: This study can guide clinicians about location, orientation, and negotiation of MMC, which can save a potential treatment failure due a missed or unexplored MMC.