Modified Mandibular Inferior Border Sagittal Split Osteotomy Reduces Postoperative Risk for Developing Inferior Border Defects.

Purpose: The purpose of this study was to evaluate the impact of a modified sagittal split osteotomy (SSO) surgical technique on the incidence of persisting inferior border defects. The secondary aim was to identify risk factors associated with the development of these complications.

Materials And Methods: The patient charts and radiographs of 276 consecutive patients who underwent bilateral SSO, performed by a single surgeon in 2 different centers from July 2012 to September 2014, were retrospectively examined. The predictor variable was length of advancement. The outcome variable was the presence or absence of an inferior border defect. Other variables included age and side of the jaw. In all cases the same surgical technique was used. All statistical analyses were performed using SAS software, version 9.4 (SAS Institute, Cary, NC).

Results: The analysis included 408 operation sites in 204 patients (132 female and 72 male patients; median age, 22 years; age range, 13 to 66 years). In 5.1% of operation sites an osseous defect at the lower border of the mandible was observed. Age at the time of surgery (P < .0001) and length of advancement (P = .0111) were identified as risk factors for the development of a persisting osseous defect at the inferior border of the osteotomy gap after SSO.

Conclusions: This study confirms the findings previously reported by our research group that the modified inferior border osteotomy technique in SSO results in a substantial lower frequency of persisting inferior border defects. Surgeons are advised to ensure that the lingual cortex of the inferior border is not included in the split during mandibular advancements, and in cases in which the advancement is more than 10 mm and/or the patient is older than 30 years, surgeons might want to consider using a bone graft or a bone graft substitute.