Surgical Anatomy of the Inferior Alveolar Nerve: A 3-Dimensional Image Study

Background: – The mandible is subjected to multiple surgical interventions, and the procedures pose a risk of injuring the inferior alveolar nerve (IAN) running inside the bone. Comprehensive anatomical information of the IAN within the mandible is required. Methods: – The authors performed a 3-dimensional imaging study, recruiting cone-beam computed tomography from 355 patients with an average age of 23.3 years. The patients received treatment in their center between 2010 and 2022. Patients were classified into 4 groups: classes I, II, and III, and cleft, based on Angle classification and cleft diagnosis. The images were analyzed to measure the distances at the ramus, angle, and body. Results: – The average distance from the lateral cortical bone to the nerve canal was longest around the second molar (5.16 ± 1.42 mm), with the class II group having the longest distance in group comparisons (5.77 ± 1.07 mm). The average distance from the mandibular angle to the nerve canal was longest in the class II group (20.03 ± 2.63 mm) in group comparisons, and longer in male patients (20.55 ± 3.02 mm) in sex comparisons. All the nerves were located above the modified Kamiishi line. In patients with unilateral cleft lip and palate, there were no significant differences in most measurements between the cleft side and the noncleft side. Conclusions: – This study provides useful anatomical information of the inferior alveolar nerve for planning and execution of surgery on the mandible. Although there was a general pattern of nerve course, differences were noted.