Abstract
Bilateral sagittal split ramus osteotomy is widely used for the surgical treatment of jaw deformity. The present study aimed to compare mastication functions, temporomandibular dysfunctions and neurosensory disturbance of the lower labiomental area during 5 years postoperatively for patients with and without mandibular asymmetry after bilateral sagittal split ramus osteotomy.
A total of 46 women who experienced occlusal improvement following bilateral sagittal split ramus osteotomy were divided into a symmetrical group (n = 22) and an asymmetrical group (n = 24) and evaluated pre- and postoperatively using appropriate testing. The control group consisted of 24 females with individual normal occlusion assessed as having normal masticatory function. Changes in mastication function over time were evaluated based on measurements of occlusal contact area and occlusal force at each evaluation time point. Temporomandibular joint function was evaluated using maximal mouth opening and the Helkimo index. The Semmes-Weinstein monofilament test was used for clinical sensory testing of the lower labiomental area, and differences in degree of sensory disturbance were statistically analyzed.
Marked decreases in function were observed for all evaluation items at 1 month after orthognathic surgery, after which gradual improvements were observed. No significant difference was observed between groups regarding recovery of occlusal contact area. Conversely, recovery of occlusal force was slower in the asymmetrical group than in the symmetrical group, with no significant difference in occlusal force. Helkimo index scores were significantly higher up to 3 months postoperatively in the asymmetrical group compared to the symmetrical group. However, these symptoms subsequently tended to resolve. With regard to neurosensory disturbance of the lower labiomental area, both groups showed considerable paresthesia immediately after surgery, but symptoms tended to subsequently stabilize and marked improvement was seen by 1 year postoperatively, with no significant differences observed between groups.
