Prevalence of Second Mesiobuccal Canals in Maxillary First Molars Detected Using Cone-beam Computed Tomography, Direct Occlusal Access, and Coronal Plane Grinding.

•The results of this study demonstrate that an MB2 canal is present up to 92% of the time.•Clinical access of teeth found more MB2 canals than viewing CBCT volumes alone (P =.032).•Exposing every patient to a preoperative CBCT scan may not be appropriate.•When the MB2 canal is not found clinically a CBCT scan can increase the chances of finding it (P <.001).