An Alternative Classification Scheme for Accessory Mental Foramen

The mental foramen (MF) is an important anatomical landmark on the mandible. MFs may occur singly or with extra foramina (accessory mental foramen (AMF)).

The aim of the present study was to discuss the importance of recognition and classification of AMFs.

This study assessed CBCT images of 593 patients (208 male, 385 female) and proposed an AMF classification scheme based on three different characteristics: (1) location of the AMF with respect to the MF; (2) relationship of AMFs with tooth apices; and (3) origin of the AMF. The chi-squared test was used to compare the qualitative data as well as descriptive statistical methods when the study data were evaluated. Significance was assessed at the p < 0.05 level.

A total of 80 AMFs were found in 71 patients. Six cases involved bilateral AMFs, whereas three cases showed double AMFs. The most common AMF location was the region posterior of the MF. Notably, all the AMFs detected in line with the mesial half of the first molar were present in female patients. Based on AMF origins, 44.5%, 48.6%, and 6.7% of the AMFs were categorized as type I, type II, and a new category identified in this study, type III.

This study revealed that some foramina locations were not considered in the previous classification. Recognition and identification of these foramina might be critical to prevent possible complications. The proposed classification scheme may facilitate this objective and can be a new focus for future studies.