Criterion for determining the prognosis of reduction in the mechanical touch threshold caused by trigeminal peripheral nerve injury

Abstract

We have reported that natural recovery was difficult in patients whose mechanical touch threshold (MTT) increased to greater than 0.84 g after orthognathic surgery. This study was performed retrospectively to investigate the MTT (measured in the mental area) for determining a difficult natural recovery after oral and maxillofacial surgery. A total of 69 patients were included in this study. The first evaluation was performed from 1 to 2 weeks after the nerve injury. The second evaluation was performed from 3 to 8 weeks after the nerve injury. The diagnostic accuracies, including sensitivity, specificity, positive predictive value, and negative predictive value, were estimated. Diagnostic efficiency for determining a difficult natural recovery was also calculated and reached its highest value at 3.0 g in the first evaluation. Therefore an MTT value greater than 3.0 g in the first evaluation is a good criterion for diagnosing difficulty in a natural recovery.