Background: The success of endodontic therapy depends on cleaning the canals with irrigants, shaping it with files and filling of the root canal with obturating materials. Various factors such as complexity of canals, accessory canals, C shaped canals etc also effects its success. The maxillary first molar tooth has complex root canal anatomy. The present study aims at detecting the mesiobuccal canals (MB2) with 3-D imaging {Cone Beam Computed Tomography (CBCT)} in permanent maxillary first molar. Materials & Methods: The present study was conducted in year 2015 and CBCT done during this period due to various reasons were retrieved from the radiology section. A total of 520 maxillary first molars were examined in CBCT images of 318 patients (Males- 160, females- 158). All images were taken from Newtom CBCT machine. All the planes such as coronal, saggittal and axial planes were evaluated using NNT software. All the measurements were done using axial plane as a guide plane.  The presence of mesio-buccal canal in mesio-buccal root, disto-buccal canal in disto-buccal root, palatal canal in palatal root and mesio-buccal 2 (MB 2) was detected first. Following angles were recorded- 1. The angle between palatal (P), distobuccal (DB) and mesiobuccal (MB) root canal orifices; and the angle between MB2, mesiobuccal (MB), and distobuccal (DB) canal orifices.  An experienced dentomaxillofacial radiologist and endodontist did all the measurements and analysis in CBCT axial sections. Results: The present study comprised of 318 patients (males- 160, females- 158). The difference was non significant (P-1). We examined total of 520 maxillary first molars which included 266 teeth in males and 254 teeth in females. The difference among both gender was non significant (P-1). Out of 160 males MB 2 was present in 82 males (51%) and absent was in 78 males (49%). The difference was non significant (P-0.1). Out of 158 females MB 2 was present in 98 females (62%) and absent in 60 females (38%). The difference was significant (P-0.04). Out of 520 maxillary first molars, 272 MB 2 was seen with the prevalence rate of 52.3%. Out of 266 teeth in males MB 2 was present in 132 (49.7%) and absent in 134 (51.3%) males. The difference was non contributory (P-1). In case of females, MB 2 was present in 140 (55%) and absent in 114 (45%) females. The difference was non contributory (P-0.2). We measured < MDP and the < MDMB2. <MDP was significantly higher in the teeth with MB2 canals as compared to teeth without it (P-0.01). < MDP and the < MDMB2 showed positive correlation. We found that with 1° increase of < MDP, there was 0.438° increase in < MDMB2. Conclusion: Author concluded that for successful endodontic therapy, the presence of MB 2 should not be overlooked. CBCT offers additional diagnostic tool in detecting MB 2 canals as there is less patient exposure as compared to CT scan and precise measurement can be done with CBCT. Clinical significance:- CBCT had made detection of accessory canals, unfilled canals etc. easier and reliable. CBCT has the advantage of viewing all the planes thus diminishing the chances of missing canals.
Key words: Cone Beam Computed Tomography, Dentomaxillofacial, Endodontic.