Positioning of the Inferior Alveolar Nerve and Surgical Implications: A Study on Thai Mandibles.

Abstract

The inferior alveolar nerve (IAN), a crucial branch of the trigeminal nerve, innervates the mandible. Precise knowledge of IAN positioning ensures surgical safety. This cross-sectional study analyzed head and neck computed tomography scans from Maharaj Nakorn Chiang Mai Hospital. Inclusion criteria comprised dentate adults. Exclusion criteria included mandibular trauma/pathology or prior surgery. The study aimed to determine IAN positioning relative to key surgical landmarks: the first molar, lingula, and mental foramen. A total of 450 Thai mandibles (900 hemimandibles) with a mean age of 36 years (58.2% male) were included. No significant differences were observed in IAN positioning relative to the first molar between the left and right sides in superior and inferior landmarks. However, the buccal distance was significantly closer on the left. The lingula distance was higher on the left, whereas that to the mental foramen was lower. Surgical implications suggest maintaining a 15-mm distance from the lower mandibular border during osteotomy and upper plate placement, restricting horizontal cuts within this 15-mm range from the lingula, and ensuring screws do not extend more than 7 mm from the buccal surface. This study provides valuable guidance for minimizing the risk of iatrogenic injury to the IAN.