A modified technique of mandibular ramus sagittal split osteotomy for prevention of inferior alveolar nerve injury: A prospective cohort study and outcome assessment

Background: Postoperative functional impairment of the inferior alveolar nerve (IAN) has been a common and well-recognized complication. Our study introduced a modified Obwegeser-Dal Pont bilateral sagittal split osteotomy (BSSO) technique and evaluated the subsequent incidence of postoperative neurosensory disturbance of IAN. Methods: In this prospective cohort study, 57 patients receiving our modified BSSO during orthognathic surgerywere enrolled. The technique contained opening the 2 ramus cortices and inserting the osteotome bypassing the IAN to avoid nerve injury. A 5-point scale self-assessment questionnaire was used to evaluate IAN neurosensory disturbance one week, six months and 12 months postoperatively. Differences between groups were analyzed using Χ2 test for categorical and Wilcoxon signed-rank test for pairwise categorical data. Results: Complete ramus splitting could be achieved in 109 (95.6%) sides. Lower lip or chin neurosensory disturbances presented in 72 (63.2%) sides 1 week postoperatively and gradually reduced to 9 (7.9%), and 4 (3.5%) at postoperative months 6 and 12, respectively. Conclusions: This BSSO technique could be safely performed with low rates of IAN exposure and injury and a low incidence of persistent neurosensory disturbance in 3.5% of patients 12 months postoperatively.