Background: The authors studied whether the incidence of inferior alveolar nerve injury in patients undergoing sagittal split ramus osteotomy differs in patients with a history of previous mandibular contouring surgery.
Methods: A retrospective chart review was completed on all patients who underwent orthognathic surgery, including bilateral sagittal split osteotomy and Le Fort I osteotomy, between 2009 and 2010. Patients were divided into two groups according to whether or not they had a history of mandible contouring. Patients who sustained inferior alveolar nerve injuries during orthognathic surgery were identified through an existing record of nerve-repair cases. The incidence of inferior alveolar nerve injury between groups was analyzed using the Fisher's exact test. Significance was defined as a value of p < 0.05.
Results: There were 168 patients (142 women and 26 men), with an average age of 25.3 years (range, 18 to 35 years). The inferior alveolar nerve injury rate in patients with a history of mandible contouring was 11.5 percent (n = 3), and that for primary sagittal split osteotomy patients was 1.6 percent (n = 5). The incidence of inferior alveolar nerve injury was significantly higher in the patients with a history of mandible contouring (p < 0.001).
Conclusions: These findings suggest that patients with a history of mandibular contouring surgery had a significantly greater risk of inferior alveolar nerve injury. Surgeons should be aware of the relative change of the inferior alveolar nerve canal in patients who have undergone mandible contouring procedures and perform sagittal split ramus osteotomy with attention.
Clinical question/level of evidence: Therapeutic, III.