Neurosensory deficit of inferior alveolar nerve after bilateral sagittal split osteotomy, advancement versus setback: An observational study

Aim: The aim of this study was to compare the incidence of inferior alveolar sensory deficits, its association with various intraoperative nerve encounter status and the possible outcome of neurosensory deficits (NSDs) of the bilateral sagittal split osteotomy (BSSO) advancement, and setback procedures. Materials and Methods: This was an observational study among the oral and maxillofacial surgeons of south India who had expertise in the field of orthognathic surgery. A self-administered questionnaire (SAQ) with closed-ended answers was prepared using Google Forms (Google Inc.), pretested, and was sent to the prospective participants selected by convenience sampling through various social media outlets. A total of 1600 participants were included, and the sample size was estimated by the formula = 4pq/d2 and assessed 800 cases each of BSSO setback and advancement surgeries. Since the study focused on the NSD of the inferior alveolar nerve (IAN) post-BSSO, the advancement procedures, setback procedures, and various nerve encounter statuses were considered the variables. All the study procedures were performed as per the ethical guidelines laid down by the Declaration of Helsinki (October 2013) after approval by the Institutions Human Ethics Committee (IHEC), Rajah Muthiah Medical College, Annamalai University. Results: Chi-squared test was used to assess the qualitative variables. The incidence of NSDs was 17.7% in the setback cases and with respect to advancement, the NSD was 15.1%, P < 0.08 indicating no statistically significant difference. When comparing the independent nerve encounter status and NSDs between the groups, the cases where the nerve got transected post osteotomy, necessitating repair as well as those needing dissection due to its presence in the proximal fragment presented with a higher incidence of NSDs which was clinically and statistically significant, P < 0.001. Conclusion: No significant difference was observed in the NSD after mandibular sagittal split advancement and setback procedures. The status of the IAN intraoperatively can influence the incidence of postoperative prolonged IAN NSDs.