Locating the MB2 Canal in Maxillary First Molars

Failure to identify and treat the second mesiobuccal (MB2) canal in maxillary first molars is a major cause of endodontic failure. While the other canal orifices are often visible upon access cavity preparation, the MB2 canal frequently remains hidden under a layer of secondary or tertiary dentin. This article highlights the clinical importance of troughing—a conservative and targeted dentin removal technique along the mesial groove—as a key step to detect and manage the MB2 canal. The prevalence and anatomical considerations are also reviewed. 1. Introduction The maxillary first molar is considered one of the most complex teeth in terms of root canal morphology. Of particular interest is the mesiobuccal root, which commonly harbors a second canal, referred to as MB2.…