LONG TERM RESULTS ON THE CORRECTION OF PROGENIA-COPARISON OF SURGERIES, ONE-JAW VS TWO-JAW

本研究的目的是评估上颌和/或下颌定位的稳定性，并观察复发的相关因素。25名日本成年人被分为两组。对一组诊断为后代的患者，采用矢状劈开法进行下颌骨后移（单颌n=13）。另一组为轻度上颌骨后移及后移畸形，采用LeFort Ⅰ型截骨术前移上颌骨，矢状劈开法后移下颌骨（双颌n=12）。在以下时间段拍摄侧位X线头影测量片：术前（T1），术后6周（T2），结果1.两组患者术前牙体形态学改变差异有统计学意义（P < 0. 05），术后6个月（T3）和2年以上（T4）牙体形态学改变差异有统计学意义（P < 0. 05）。2.手术形态改变：下颌骨在B点（X）后移8.67 mm（单颌），6.19 mm（双颌），上颌骨在ANS点（X）前移1.73 mm，总移动量（X）7.92 mm（双颌）。下颌骨在X轴上的移动量单颌组明显大于双颌组（T2-T1/14-T2）SNB角为11.6%（单颌）、4.1%（双颌），SNA角为9.1%（双颌）。两组在B（X）点、U1、L1点上的差异有统计学意义。总结两颌组复发率低于单颌组，两颌组术后骨骼和牙齿的稳定性均优于单颌组。

The purpose of this study is to evaluate the stability and to observe the factors related to relapse of maxillo-and/or mandibular positioning. The subjects of 25 Japanese adults were divided into two groups. On one group, diagnosed as progenia, the retropositiong of mandible by sagittal splitting method was performed (one-jaw n=13). On the other group, diagnosed as slight retromaxillism and progenia, the advancement of maxilla by Le Fort I osteotomy, retropositioning of mandible by sagittal splitting method was performed (two-jaw n=12).The lateral cephalometric radiograms were taken at the following periods : preoperative (T1), postoperative 6 weeks (T2), 6 months (T3) and more than 2 years (T4) after surgery.Results1.The significant difference between 2 groups were observed at the pre-operative morphology of dento-facial complex.2.Morphological changes by operation ; retropositioning of mandible at the point of B (X) was 8.67mm (one-jaw), 6.19mm (two-jaw), (advancement of maxilla at the point of ANS (X) was 1.73mm, total amount of movement (X) was 7.92mm (two-jaw). As to the amount of movement of mandible on the X axis the one-jaw group is significantly larger than the two-jaw group.3.The relapse rate for long term (T2-T1/14-T2) at the angle of SNB was 11.6% (one-jaw), and 4.1% (two-jaw), at the angle of SNA was 9.1% (two-jaw).4.Significant difference on each group was observed at the point B (X), over jet (one-jaw), over jet (two-jaw).5.Significant difference between two groups was observed at the point B (X), U1 and L1.SummaryLess relapse was observed in the two-jaw-group than in the one-jaw group.Both skeletal and dental stability after surgery was better in the two-jaw group.