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Abstract

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.

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