Аннотация:【Objectives】 To evaluate horizontal changes of the proximal mandibular segment after mandibular setback surgery using 3-dimensional computed tomography (3-D CT) .【Study Design】 This study included 66 patients who underwent bilateral sagittal split ramus osteotomy for correction of mandibular prognathism.With the use of 3-D CT data obtained preoperatively (T1) , immediately postoperatively (T2) , and 6 months postoperatively (T3) , horizontal changes of the proximal mandibular segment, including the intercondylar width, the intergonial width, and the frontalramal inclination were evaluated.【Results】 The value of the right frontal-ramal inclination was 11.43±1.36°at T1, 11.91±1.96°at T2, and 10.7±1.5° at T3.The values of the left frontal-ramal inclination were 6.10±1.03°at T1, 8.17± 1.66° at T2, and 7.66±1.65°at T3.The values of the intergonial width were 99.67±1.67mmat T1, 98.24±1.72mmat T2, and 97.08±1.71mm at T3.The intergonial width was significantly decreased at T3 compared with T1 (P < .001) .The values of the intercondylar width were 123.51±1.66mmat T1, 123.9±1.66mm at T2, and 122.88±1.58mmat T3. Conclusions : Lower facial width at mandibular angle region decreased immediately after mandibular setback surgery and showed further decreases during the postoperative period.
