抄録
The purpose of this study was to investigate the long-term changes of craniofacial morphology in mandibular prognathism patients treated with two-jaw surgery and to evaluate the stability after surgery. Lateral cephalograms of seven patients (two males and five females) studied for more than two years after surgery, were analyzed for evaluation of craniofacial changes. The materials were obtained at eight stages between the initial and the latest examinations. Dentofacial changes were analyzed and compared between the stages.
The results were as follows:
1. The maxilla was moved forward and downward by surgery (average; anteriorly 4.2mm, inferiorly 3.3mm). Anteroposteriorly, excellent postoperative stability was achieved, although the maxilla slightly displaced posteriorly during intermaxillary fixation. The maxilla was displaced superiorly 1.5mm on average between immediately and 3 months after surgery. However, the vertical change of the maxilla was minimum after 6 months.
2. The mandible was moved backward 12.9mm on average after surgery. Postoperative stability was achieved, while the mandible was displaced forward 1.4mm on average between removal of intermaxillary fixation and 6 months after surgery. A significant negative correlation was found between the amounts of mandibular setback and forward displacement.
3. The maxillary and mandibular incisors moved lingually during intermaxillary fixation and then tended to be slightly inclined labially. After one year, no obvious changes in inclination of upper and lower incisors were observed in most cases.
4. Appropriate overjet has been maintained, while overbite decreased slightly in some cases after surgery. At the latest examination, an acceptable occlusal relationship in the anterior region was maintained in all cases.
From these findings, it was suggested that long-term craniofacial stability and acceptable occlusal relationship in the anterior region were obtained in most cases by two-jaw surgery. On the other hand, vertical relapse of the maxilla occurred immediately after inferior maxillary repositioning. Therefore, it was suggested that an integrated treatment planning be established to prevent vertical relapse of the maxilla.
