Undetected Small Accessory Mental Foramina Using Cone-Beam Computed Tomography.

INTRODUCTION: The accessory foramina could not be identified on some imaging modalities such as surface-rendered images. The purpose of this study was to investigate the ability of surface-rendered images in detecting these foramina.

MATERIALS AND METHODS: We analyzed 20 accessory mental foramina (AMF) in nine mandibles removed from cadavers with cone-beam computed tomography (CBCT) and assessed in surface-rendered images. All AMF were divided into three groups depending on their visibility.

RESULTS: Group 1 included AMF that were clearly visible as foramina, Group 2 were not clearly visible but could be recognized with concave parts, and Group 3 were not visible and the smooth surface of the bone was observed. Group 1 ranged from 1.3 to 5.1 mm(2), Group 2 from 0.3 to 3.8 mm(2), and Group 3 from 0.2 to 1.1 mm(2). A statistically significant difference in the mean size between Groups 1 and 3 was observed. Even if the AMF are smaller (e.g., 1 mm in diameter), they should still be avoided to prevent injury.

CONCLUSIONS: The clinician should be aware that smaller foramina might not be detected on these images.