Inferior alveolar nerve function after sagittal split osteotomy of the mandible: correlation with degree of intraoperative nerve encounter and other variables in 496 operations

A total of 1034 patients who had undergone orthognathic surgery were examined after 2 years; 818 had been treated with varying types of mandibular osteotomy such as vertical ramus osteotomy, sagittal split ramus osteotomy, and genioplasty. Neurosensory function in the mental nerve region was assessed by evaluating light touch perception.The incidence of neurosensory deficiency was 216/548 (39%) after sagittal split ramus osteotomy, 26/140 (19%) after extraoral vertical ramus osteotomy, 9/78 (12%) after genioplasty and 60/650 (9%) after intraoral vertical ramus osteotomy. Additional genioplasty increased both the incidence and severity of neurosensory disturbance after intraoral vertical ramus osteotomy but did not significantly influence the neurosensory function after sagittal split ramus osteotomy.The incidences of neurosensory disturbance after mandibular osteotomies in this report correspond well with those previously reported, but the incidence of almost 40% after sagittal split ramus osteotomy must be considered a disquieting drawback of the procedure.