Long-term follow-up and relapse of the mandible after surgical correction (intraoral oblique sagittal splitting osteotomy) for mandibular prognathism
1989 Volume 38 Issue 1 Pages 131-159
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1989 Volume 38 Issue 1 Pages 131-159
Postoperative observation and relapse following mandibular set-back were investigated to clarify the timing and mechanism of relapse. The subjects were 19 patients of only mandibular prognathism and 18 patients of mandibular prognathism with anterior open bite. All patients underwent intraoral sagittal splitting osteotomy. Analysis of postoperative changes of segments were carried out by means of cephalograms taken at adequate intervals.
In cases of only prognathism both segments were surgically reduced. In open bite cases, the distal segment was moved postero-superiorly and the proximal segment postero-inferiorly. During intermaxillary fixation, the distal segment remained stable, but the proximal segment returned almost to the preoperative position in both groups. Until 6 months postoperatively the distal segment moved antero-superiorly in the only prognathism group. In the other group, both segments remained almost stable. After 6 months, both segments kept their positions in the only prognathism group. In the other group, the distal segment presented slight anterior movement.
In longitudinal observation with postero-anterior cephalograms, the proximal segment shifted laterally at the operation in both groups. Until releasing the intermaxillary fixation, the segments returned to their preoperative position in almost all cases.
Little association was found in multiple regression analysis between preoperative skeletal patterns, surgical changes and relapse. However, changes of segments during fixation were better than other predictors. Without limitation of predictors, clinically suitable functions relating vertical and horizontal relapse were obtained.
In conclusion, a multiple regression technique in which the predictors consisted of several variables of data from preoperation to the time of release of fixation, suggested the possibility of predicting relapse.
