Sensory retraining following orthognathic surgery: effect on threshold measures of sensory function.

The purpose of this analysis was to examine the effect of sensory retraining on sensory function after bilateral sagittal split osteotomy (BSSO). A total of 186 subjects were enrolled in a multi-centre double-blind two parallel group stratified block randomized clinical trial. Subjects were randomized to group immediately after surgery. Threshold measures for contact detection, two-point discrimination and two-point perception were obtained on the chin before and 1, 3 and 6 months and 1 and 2 years after surgery. The ratio of each threshold measure (post-surgery value/pre-surgery value) was calculated to characterize subjects' impairment. A general linear mixed model was fit for the impairment to examine the effect of the sensory retraining before and after adjusting for demographic, surgical and psychological factors. On average, two-point perception was less impaired in subjects who were retrained than in those who were not retrained (P = 0.04). Significant recovery continued up to 6 months after surgery for contact detection and two-point perception and up to 24 months for two-point discrimination. Older subjects experienced more impairment in two-point discrimination than younger subjects (P = 0.009). Subjects who received maxillary surgery in addition to mandibular surgery experienced more impairment on the chin in both two-point discrimination (P = 0.0003) and perception (P = 0.0013) than subjects who received mandibular surgery only. Psychological factors did not explain additional variability in subjects' impairment post-surgery. These finding indicate that a simple non-invasive exercise programme initiated shortly after orthognathic surgery can alter the way patients experience or respond to tactile stimulation long after the exercise regimen has stopped.