Lingual nerve injury in association with sagittal ramus osteotomy and bicortical screw fixation: a review of 523 procedures in 262 subjects.

The purpose of this study was to assess the frequency of irreversible lingual nerve (LN) injury in patients undergoing sagittal ramus osteotomies (SRO) with bicortical screw fixation. A retrospective cohort study of patients treated by a single surgeon was performed (follow-up 2-11 years). The sample consisted of a series of subjects with a bimaxillary dentofacial deformity (DFD). The SRO and bicortical screw fixation techniques were consistent. The primary outcome variable was the prevalence of irreversible LN injury. Two hundred sixty-two subjects undergoing 523 SROs with bicortical screw fixation met the inclusion criteria. Average age at operation was 25 years (range 13-63 years) and there were 134 females (51%). The majority of SROs were fixated with three bicortical screws (92%). Simultaneous third molar removal was done in 209 of the 523 SROs (40%). For primary mandibular deficiency subjects (n=40), the mean mandibular advancement was 11.0mm (range 5-17mm), with 42.5% undergoing counter-clockwise rotation. In the study group (n=523 SRO's) there was one irreversible LN injury (<1%). This study confirmed a lack of association of LN injury at the time of SRO with sex, age at operation, simultaneous removal of a third molar, use of bicortical screw fixation, pattern of DFD, and extent of mandibular advancement.