Objective: This study aimed to investigate the root canal system morphology of maxillary first molar mesiobuccal (MB) roots in a Brazilian sub-population using micro-computed tomography.
Methods: Ninety-six MB roots were scanned with a micro-CT (Skyscan 1173, Bruker). Three-dimensional images were analyzed regarding the number of pulp chamber orifices, the number and classification of the canals, the presence of accessory canals in different thirds of the root as well as the number and type of apical foramina.
Results: A single entrance orifice was found in 53.0% of the samples, two in 43.9% and only 3.1% had three orifices. The second mesiobuccal root canal (MB2) was present at some portion of the root in 87.5% of the specimens. A single apical foramen was present in 16.7%, two in 22.9%, and three or more foramina in 60.4% of the roots. Only 55.3% and 76.1% of the root canals could be arranged by Weine’s and Vertucci’s classifications, respectively.
Conclusion: The number of orifices at the pulp chamber level could not work as a predictor of the MB2 presence. The most prevalent canal configuration was Weine type IV / Vertucci type V. The anatomical complexity of the MB root could not be entirely classified by the current most accepted classifications.