|Budget Amount *help
¥2,300,000 (Direct Cost: ¥2,300,000)
Fiscal Year 2000: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1999: ¥1,800,000 (Direct Cost: ¥1,800,000)
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.
1.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.
Less 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.