When to perform cone beam computed tomography (CBCT) in primary root canal treatment? A CBCT-based cross-sectional study on the prevalence of MB2 canal in maxillary first molars

OBJECTIVES: CBCT provides insights into the presence of an additional root canal in maxillary first molars. Since the maxillary first molar is one of the teeth most likely requiring root canal treatment, and young people are more sensitive to radiation exposure, this study aimed to evaluate the prevalence of MB2 canals in healthy, untreated maxillary first molars using CBCT. METHODS: CBCT scans of maxillary first molars of 167 patients were categorized according to the classification systems of Wein, Vertucci, and Ahmed. The number of root canals and the presence of an MB2 canal were analyzed descriptively. The associations between the presence of an MB2 canal and various factors, including gender, position in the dental arch, and age group, were examined using a chi-squared test at a significance level of P < .05. All analyses were performed using SPSS. RESULTS: A second mesiobuccal root canal was found in 63% (Weine) and 66% (Vertucci) of the examined maxillary first molars, respectively. Significantly fewer women exhibited a second mesiobuccal root canal compared to men. No statistical differences were observed regarding the position in the dental arch or the different age groups. The most frequently observed root canal morphologies were Vertucci Type I and IV (34% each), followed by Type II (23%), Type VI (6%), Type V (2%), and Type III (1%). In the Weine classification, Types I and II (35% each) were most common, followed by Type III (29%) and Type IV (1%). In the Ahmed classification, the most common configuration was 3MB2-2DB1P1. CONCLUSIONS: A MB2 canal was present in about two-thirds of maxillary first molars, with significantly lower prevalence in women but no association with tooth position or age. ADVANCES IN KNOWLEDGE: This study provides updated prevalence and morphological data on MB2 canals, showing they occur in about two-thirds of maxillary first molars and differ by gender. These findings may guide future diagnostic approaches and support more targeted use of CBCT in endodontic treatment planning.