Retrospective evaluation of positional changes in the inferior alveolar nerve following mandibular setback and advancement surgeries: Effects on neurosensory recovery

This study aimed to evaluate the effects of positional changes in the inferior alveolar canal after sagittal split osteotomy on neurosensory recovery. By examining the pre- and postoperative positions of the IAC in patients undergoing orthognathic surgery, the relationship between these changes and neurosensory disturbances was investigated. The study was conducted retrospectively on 40 patients with Class II or Class III dentofacial deformities who underwent orthognathic surgery at Bezmialem Vakıf University between 2017 and 2024. Inclusion criteria required a minimum follow-up period of 6 months, preoperative and postoperative (≥6 months) computed tomography scans, and completion of a subjective neurosensory evaluation survey. Three-dimensional reconstructions of the mandible and IAC were generated using Nemo Fab and Mesh Mixer software. Positional changes of the IAC along the x, y, and z axes were measured, and the severity of neurosensory disturbances was assessed with a 10-item visual analog scale questionnaire. Postoperative analyses revealed significant mediolateral and vertical positional changes in the IAC; however, these displacements were not statistically significant in terms of their impact on long-term neurosensory recovery (p > 0.05). Although larger mandibular movements increased the risk of transient sensory disturbances, recovery rates were found to be independent of IAC positional changes. The findings demonstrated that the risk of inferior alveolar nerve injury is comparable in both advancement and setback surgeries. Postoperative sensory disturbances cannot be explained solely by the type of deformity but are also influenced by the location of the mandibular canal and the three-dimensional displacement of the nerve. It can be concluded that preoperatively, closer proximity of the IAC to the outer cortex increases the likelihood of sensory loss. Nevertheless, in patients undergoing orthognathic surgery, sensory dysfunction alone was found to have a limited effect on treatment satisfaction and social life.