Prevalence and anatomical characteristics of the accessory mental foramen: a study using cone beam computed tomography.

The purpose of this study was to evaluate the prevalence of accessory mental foramina (AMFs) through the use of cone beam computed tomography (CBCT). The secondary purpose was to analyze the location of AMFs, mean distance from the nearest tooth, mean distance from the alveolar bone crest, exit angle dimensions, and whether sex, side of the mandible, or racial disparities exist. Two hundred CBCT scans were analyzed for the presence and characteristics of bifurcations of the inferior alveolar nerve. AMFs were observed in 11.5% of patients and 6.5% of all hemimandibles examined. The majority of patients with 1 or more AMFs were female (60.9%). Bilateral AMFs were found in 1.52% of patients. The location of the AMF relative to the mental foramen (MF) was evaluated, and 30.0% of AMFs were located anterosuperiorly and 23.3% posterosuperiorly to the MF. Associations between patient sex and the greatest and smallest diameters of AMFs, circumference and area of AMFs, and ratio of AMF-MF area were evaluated via statistical analysis. Additional analyses evaluated the prevalence on each side of the mandible as well as the association between race/ethnicity and occurrence of AMFs. Statistical analyses showed no association between the occurrence of AMFs and sex, side of the mandible, or race/ethnicity of the study population. This demonstrates the importance of preoperative CBCT prior to all mandibular surgery to reduce the risk of injury to the neurovascular bundles that pass through AMFs.