Four‐dimensional assessment of facial expression before and after orthognathic surgery in skeletal Class III patients

Aim: It is widely known that orthognathic surgery affects changes in facial soft tissue morphology. However, the effect of orthognathic surgery on facial expression remains to be verified. The purpose of this study was to examine the pros and cons of the effects of orthognathic surgery on facial expression in skeletal Class III patients. Methods: Fifteen patients (5 males, 10 females) were captured pre-surgery and at 6 months' post-surgery using Kinect camera while performing facial soft tissue movements (opening mouth, smiling, and blowing). The three-dimensional coordinates, amount of movement, and velocity of the eight facial soft tissue landmarks during motion were obtained. As controls, 15 Japanese healthy volunteers with Class I occlusion were included. Results: Differences in the three-dimensional coordinate values during movement were confirmed, and there were some landmarks in the lower face region of the preoperative patient that showed significant differences compared with the control. Total amount of movement and velocity of Pogonion during smiling were significantly smaller than those of the control group, but there was no significant difference between the control and postoperative groups at any landmarks after surgery. It was suggested that patients with skeletal Class III may have limited movement in some movements, and it was confirmed that with orthognathic surgery, the aspect of movement would be similar to that of the control. Conclusions: Orthognathic surgery may be beneficial to the facial muscles without limiting facial movements.