Methods: 10 patients aged 16 to 21, presented with mandibular prognathism were scheduled for a BSSO procedure (20 mandibular sides). All patients underwent preoperative CT scanning of the mandible from which two clinicians determined the precise location of the IAN. The assessment of the IAN sensation was evaluated by monitoring the lower lip and the chin skin perception preoperatively and 1week, 1 month, 3 months, 6 months, and 1 year post BSSO procedure. The patients were administered a 5-point scale assessment questionnaire.
Results: The exact location of IAN was successfully determined in all patients by both clinicians (inter examiners' reliability was 96%). There were almost no significant differences between the patients' sensation scores at the chin skin and lip sites in each side and within the time process. This allows the unification of the chin and lip values into one averaged value for each side. No significant differences were found between the two sides for the10 patients. Presurgical identification of the IAN course significantly reduced neurosensory disturbance. All the patients reported complete recovery of the IAN perception after 1 year. However 1 week after surgery 90% of the patients reported neurosensory deficiency. This was significantly improved after 1 month among 60% of the patients (P=0.005), after 3 months among 20% of the patients (P=0.006), and after 6 months all the patients reported normal sensation.
Conclusion: Imaging the IAN using CT scanning is efficient for precisely locating the IAN pathway. This may contribute to minimizing nerve damage during BSSO procedures and thus reduce the impairment of IAN sensation.