Evaluation of orthognathic surgery on masticatory efficiency and muscle activity

The aim of this study is to evaluate the effect of orthognathic surgery on masticatory efficiency and electromyographic activity of the masseter and anterior temporal muscles in skeletal Class III patients and to compare with Class I individuals. The study was performed on 25 subjects, who were suitable for research criteria, between April 2014 and October 2015. For assessment of the masticatory efficiency, the individuals were instructed to chew standardized round tablets of silicon impression material. The sample was separated using sieve analysis then cumulative weight percentage was calculated for each individual. From these percentages, the median particle size were estimated. The participants were submitted to bilateral evaluation of bipolar surface electromyographic activity of the masseter and anterior temporal muscles. Following the orthodontic decompensation treatment, a stabilization splint was fabricated and instructed to a full time wear during 8 week until the surgical procedure. Recordings were performed at preoperatively before splint application (T0), preoperatively after splint application (T1), 1 month after orthognathic surgery (T2) and 6-8 month after orthognathic surgery (T3). In the anterior temporalis muscle activity, significant decrease occurred with the use of stabilization splint. From T0 to T2, significant decrease in the masticatory function was observed due to trauma and intermaxillary fixation. A significant increase of the masticatory efficiency and muscle activity was found at T3 with the improvement of the occlusion but it could not reach the control group data. In conclusion, orthognathic surgery provided a better masticatory function by the improved occlusion of the individuals with dentofacial deformity. Keywords: Orthognathic surgery, occlusal splint, electromyography, mastication