下颌支矢劈后退术后近心骨段位置变化及对面型的影响

摘要

目的:分析下颌支矢劈后退术后下颌角间宽度(intergonial width,IGW)和近心骨段两者变化的规律及其变化对面型的影响.方法:选择天津医科大学口腔医院颌面外科收治的骨性下颌前突患者20例,进行头影测量,采用SPSS15.0软件包进行统计分析.结果:20例患者的IGW在术后均增加,其变化与下颌后退量呈显著正相关(r=0.917,P＜0.01),而与右升支外展角、升支切线角、后面高并无相关性；术后1周与术前相比,Go至坐标原点的距离显著增加(P＜0.01),而∠Ar-Go-Me及升支-Y轴夹角呈显著减小(P＜0.01)；两侧下颌支下段间宽度明显增宽,由下至上下颌支间宽度的变化值存在递减趋势.结论:近心骨段在冠状面上发生了下颌角外展、髁突内旋的转动,矢状面上发生了自身旋转及整体后移,此变化可能会改变患者的面型.研究近心骨段位置的变化规律对临床有重要指导意义.%Objective To analyze changes in proximal segments positions in patients with mandibular prognathism after mandibule setback by BSSRO operations and to study interrelationship between repositioning of the proximal segment and change in IGW. Methods Twenty patients underwent mandibule setback by BSSRO operations.Pre and postoperative posteroanterior and lateral cephalometric radiographs were collected and used for cephalometric analysis and statistical analysis. Results IGW increases from T, (103.54±.05 mm, 1 week preoperatively) to T2 (108.54 ±5.22mm, 1 week postoperatively) with mean value of 5mm (ranged from 0.7mm to 13.9mm) were observed in all the 20 patients.Correlative analysis showed significant positive correlation between IGW and the quantity of mandible setback, but other changes were not significantly correlated with the changes in intergonial width.From T1 to T2,The distance between Go and N is significant increased (P<0.01), whereas the angle of Ar-Go-Me, the angle between Y axis and mandibular rami are significant decreased (P<0.01). Meanwhile.the width between the right and the left mandibular rami showed a degressive tendency. Conclusion Displacement forms of the proximal segment:On the frontal view, it rotated on pivot of middle part, the mandibular angle reached out, and the condyle rotated mesially;On the saggital view, it also rotated and move back with the condyle towards posterosuperior direction.Those changes have many adverse effects on the patient's aesthetic preference and facial contour, which can change the patient's facial morphology.