Radiologic Risk Factors for Persistent Mandibular Nerve Neurosensory Disturbance Following Sagittal Split Osteotomy.

Purpose: Neurosensory disturbance (NSD) occurring in the lower lips and chin is a major postoperative complication related to bilateral sagittal split osteotomy (SSO). The purpose of this study is to identify preoperative radiographic findings following SSO procedure associated with persistent NSD.

Methods: This retrospective cohort study analyzed data for consecutive patients who underwent SSO. Primary predictor variables, including ramus width, mandibular body height, mandibular angle length, gonial angle, distance from mental foramen to distal aspect of mandibular second molar (MFD), and measurement of bone marrow space (BMS), were examined in a series of radiographic images. The primary outcome variable was NSD. Patients with NSD were divided into 2 groups based on findings obtained 1 year postoperatively: persistent, for those with NSD remaining after 1 year, and transient, when NSD occurred for less than 1 year. Covariates included sex and age. Comparisons were analyzed by use of Mann-Whitney U test or χ test. Multivariate analysis was performed using step-wise logistic regression to determine significant factors related to persistent NSD. A P value .005 or less was considered statistically significant.

Results: Of the 349 sides investigated, the persistent NSD group consisted of 59 sides (16.9%), while the transient NSD group consisted of 290 sides (83.1%). The occurrence of persistent NSD was correlated with age (P < .05), MFD (P < .001), mandibular body height (P < .05), and BMS (P < .001). Multivariate logistic analysis also showed a significant association of MFD (P < .001) and BMS (P < .001).

Conclusions: Preoperative MFD and BMS are radiographic findings that are associated with an increased risk for persistent NSD following SSO procedure.