| Summary: | 碩士 === 國立臺灣大學 === 臨床牙醫學研究所 === 96 === Orthognathic surgery is a common treatment option for improving facial esthetics and restoring occlusal function due to severe dentofacial deformity. There were many studies searching the factors associated with facial improvement. However, little were the articles focusing on the functional improvement. Therefore, the effects y of the structural and kinematical changes after orthgnathic surgery are investigated in current study.
Ten subjects (average age: 25.5 y/o) who received mandibular setback surgery (BSSO and rigid fixation) were included. Before surgery (T1) and post-surgery (T2), all subjects were arranged for CBCT scan to analyze the changes of condylar position in experiment I. In experiment II, all subjects were under upright head position calibrated with cervical range of motion instrument, maximum mouth opening between upper and lower incisor edge by using the ruler with 0.5 mm accuracy were measured. And under this position, the horizontal, sagittal and chewing stroke movements were captured and analyzed by the optoelectronic recording device (Vicon 512®). This set-up yielded a working volume of 50X50X50 cm3 with spatial resolution of 0.0008mm and absolute system measuring error being less than 0.4 mm.
The present results: (1) most of the condylar position was changed in axial view after BSSO and rigid fixation. (2) in kinematical measurements, the range of MMO, horizontal, sagittal border movement and chewing stroke decreased but became more consistent with better occlusal guidance after surgery under optoelectronic analysis.
The conclusion of present study : (1) there were some degree of lateral movement of the proximal segments after rigid fixation(T2), the inter-condylar width was increased 1.42 mm in average, range from 0.9~2.2 mm. Inward movement was also detected from the axial view in most of the subjects. (2) the extent of MMO and border movement were decreased in linear measurement (4 mm in average, range from 2~6 mm), but the degree of MMO when expressed in angular amount was not significantly changed after the surgery.
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