A Retrospective CT Study to Evaluate the Horizontal and Vertical Positions of the Mental Foramen and the Prevalence of Accessory Mental Foramen in Western Tamilnadu, India

Introduction: The mental foramen is a small opening on the surface of mandible through which the mental nerve and vessels pass, providing sensory innervation and blood supply to the lower lip and chin. Exact identification of its position and anatomical variations, like an accessory mental foramen are important to prevent nerve injury during dental and maxillofacial procedures. This study was done to evaluate the horizontal and vertical positions of the mental foramen and to assess the prevalence of accessory mental foramen using computed tomography. Materials and Methods: This retrospective study was conducted in the Department of Radiology at a tertiary care hospital in western Tamil Nadu after Institutional Human Ethics Committee approval. A total of 392 computed tomography scans of head and face which included the mandible were analyzed. The horizontal position of the mental foramen was classified based on its relationship to adjacent teeth, and the vertical position was assessed in relation to the premolar apex. The presence of accessory mental foramen was also evaluated bilaterally. Results: The most common horizontal position of the mental foramen was position 4 on both right (56.6%) and left (53.1%) sides, followed by position 3. Vertically, position 2 was the most frequent location on both sides. Accessory mental foramen was present in 6.9% of the individuals on right-side and in 6.4% on left-side. A high degree of bilateral symmetry was observed. Conclusion: The mental foramen most commonly lies in the premolar region and in alignment with the premolar apex, though anatomical variations exist. Computed tomography allows precise localization of the mental foramen and its variants, aiding safer clinical and surgical practice.