Neurosensory disturbance of the inferior alveolar nerve after bilateral sagittal split osteotomy: a systematic review.

PURPOSE: The evaluation of neurosensory disturbance of the inferior alveolar nerve (IAN) can be performed by purely subjective, relatively objective, or purely objective methods. The aim of this study was to provide a systematic review of the incidence of inferior alveolar nerve sensory disturbance after bilateral sagittal split osteotomy, as well as the frequency of recovery of sensory function using objective methods of evaluation only. MATERIALS AND METHODS: Searches were conducted employing MEDLINE, Scirus, and the Cochrane Central Register of Controlled Trials (CENTRAL). Seven studies were included in this review. RESULTS: This systematic review has shown that the frequency of nerve impairment evaluated by subjective methods was higher than that indicated by studies adopting objective methods at each time of follow-up considered. In particular at the seventh postoperative day the frequency obtained using the objective methods was 63.3% while that obtained with subjective methods was 83%. At 1 year follow-up a frequency of sensory impairment of 12.8% was obtained using objective methods and a frequency of 18.4% when subjective methods were used. The data were analysed using the index of inter-rater reliability (Cohen's Kappa) with the degree of nerve damage evaluated by objective methods considered the "gold standard." The value of Cohen's Kappa at 1 week follow-up is 0.53; at 1 year follow-up it increased to 0.90. CONCLUSIONS: On the basis of these results, objective methods provide the most sensitive diagnostic tests at early controls-within 3 months of the operation. At later control points the sensitivity increases and the inter-rater reliability is satisfactory.