Abstract

Neurosensory disturbance is a common complication of bilateral sagittal split osteotomy (BSSO). This study focuses on the evaluation of factors affecting neurosensory disturbance after BSSO. Furthermore, the study focuses on the measurement of neurosensory disturbance with easily available bedside tests, not only on evaluating the state of sensory disturbance at each follow-up, but also on predicting the potential for recovery. Moreover, panoramic radiography, computerized tomography (CT) and conventional spiral tomography are assessed on locating the mandibular canal.

The study was carried out involving a total of 50 patients undergoing BSSO for the correction of mandibular deficiency. In addition, 20 voluntary healthy students participated in this study. Questionnaires, a battery of neurosensory tests and preoperative imaging of the mandibular canal were used.

A high incidence of neurosensory disturbance of the lower lip and chin was found after BSSO. However, recovery of sensation occurred with increasing frequency during the follow-up, and after one year sensation of the lower lip and chin returned to the presurgical situation in most patients. A prolonged neurosensory disturbance was more frequent in older patients, in large surgical movements of the mandible and in cases where the inferior alveolar nerve was manipulated during surgery. The bedside tests used in this study correlated well with the patients' subjective evaluation of neurosensory disturbance, and the repeatability of these tests was good. Furthermore, the sensibility testing of the mandibular teeth correlated well with the other tests and patient's subjective evaluation. Four days after surgery, sensibility testing of the mandibular teeth was an efficient test alone to predict the recovery from neurosensory disturbance. On radiographic imaging, the risk for neurosensory disturbance after BSSO could not be predicted from the panoramic radiograph. Before BSSO, CT was the best method to visualize the buccolingual location of the mandibular canal.

After BSSO, a clinical follow-up using a battery of mechano- and nociceptive tests in the examination of sensation of the lower lip and chin, sensibility testing of the teeth, and subjective evaluation is needed. CT should be a part of treatment planning of the patients with thin rami or severe asymmetries of the mandible.