1992 Volume 2 Issue 2 Pages 85-96
The purpose of this study is to investigate the long-term stability of jaw relationship and occlusion after the surgical orthodontic treatment of mandibular prognathisms and skeletal open bites. Subjects consist on fourteen adult patients (3 males, 11 females) that ten patients were done the sagittal splitting ramus osteotomy and four patients were done the two jaw surgery (Le Fort I ostetoomy plus saggital splitting osteotomy). They were put under observation during over five years after treatment until the latest record (T4-T6: 7 years in an average). The results were as follows:
1) At the sagittal splitting ramus osteotomy group (Table 3), Pogonion was retruded 8.7mm in an average due to the operation, and further was repositioned 0.4mm backward during T4-T6. There was one case who was recognized the forward relapse over 1.5mm. After the vertical distance between Nasion and Menton was decreased 2.6mm during active treatment (T1-T4), it was increased 1.8mm during T4-T6, and there was one case who became a slight open bite with mandibular clockwise rotation.
2) At the two jaw surgery group (Table 4), Pogonion was retruded 11.5mm due to the operation, and was repositioned 0.9mm forward during T4-T6. Point A was advanced 4.3mm due to the operation, and was repositioned 0.9mm backward like relapse during T4-T6.
3) Lower incisors were tipped labially for decompensation during T1-T4, and were inclinedlingually during T4-T6. Upper incisors were tipped lingually during T1-T4, and still more were inclined lingually for many cases during T4-T6.
