Changes in the Morphology of Mandibular Symphysis Secondary to Pre-surgical Dental Decompensation in Class Ⅲ Malocclusion

安格列氏三級咬合在術前矯正後下顎骨聯合的形態變化

王聿靖(Yu-Ching Wang) ； 蔡一民(I-Ming Tsai) ； 陳慧玲(Hui-Ling Chen)

《中華民國齒顎矯正學雜誌》 21卷2期 (2009/06) Pp. 17-23

https://doi.org/10.30036/TJO.200906.0003

摘要

本研究的目的是以測顱X光片分析安格列氏三級咬合的病患在術前矯正治療後，其下顎骨聯合的形態變化。有13位要接受正顎手術的三級咬合病患，為使下顎經雙側矢狀劈開術能獲得更大的後退量，必須先以矯正治療改善下顎門牙角度。經由治療開始前及術前測顱X光片的比較可以得知：術前矯正將下顎門牙向唇側傾斜，使其與下顎骨的角度趨於正常，此移動會使下顎骨聯合的B點寬度變窄、骨聯合高度及骨聯合總體高度增加。因此在進行術前矯正時，需注意下顎骨聯合的厚度與下顎門牙的移動量，避免將牙齒移動到齒槽骨之外。

關鍵字

下顎骨聯合 ； 術前矯正

並列摘要

The purpose of this study is to evaluate the changes in morphology of mandibular symphysis in Class Ⅲ malocclusion after pre-surgical dental decompensation. Thirteen patients underwent orthognathic surgery to correct Class Ⅲ skeletal and dental malocclusions. The dental decompensation was indicated for these patients to gain greater setback amount of bilateral sagittal split ramus osteotomy. The morphology was assessed through lateral cephalograms obtained initially and preoperatively. After pre-surgical dental decompensation, the sagittal discrepancies were maintained. There was statistically significant lower incisor proclination, and both the FMIA and IMPA approximated the norms. When the mandibular incisors were labially inclined, the thinner cancellous bone was characterized by the decreased width between B to B' point. The symphyseal height and total height were greater after dental decompensation due to orthodontic tooth movement affecting the position of the alveolar landmark such as malv point (midpoint of anterior alveolus). Therefore, we must pay attention to the boundary limit for tooth movement in presurgical dental decompensation for subjects with lingual inclination of the mandibular incisors and the thin cancellous bone.

並列關鍵字

mandibullar symphysis ； pre-surgical orthodontic treatment