Objective: To test the hypothesis that there is no difference in the stability of the hard and soft tissue changes following a surgical mandibular setback using a sagittal split ramus osteotomy or an intraoral vertical ramus osteotomy. Materials and Methods: The samples consisted of 45 female patients with mandibular prognathism, who were divided into two groups. Twenty-three underwent a sagittal split ramus osteotomy (SSRO) with rigid fixation by titanium mini-screws and maxillomandibular fixation (MMF) for 14.0 ± 0.7 days. Twenty-two underwent intraoral vertical ramus osteotomy (IVRO) without rigid fixation, and MMF was released 21.5 ± 3.3 days after surgery. Data were collected from standardized cephalometric radiographs taken at the start of preoperative orthodontic treatment (T1), immediately after surgery (MMF, T2), and the completion of postoperative treatment (T3). Angular measurements were compared on each of T1, T2, and T3. Results: There were no significant differences in the pretreatment hard and soft tissue morphology between the SSRO and IVRO. However, when fixation was released, the mandible was posteriorly positioned in the IVRO group. In the soft tissue profile, the mental region was located backward in the IVRO group at postoperative stage (T3). Conclusions: The hypothesis is rejected. The soft tissue profile of the IVRO group especially showed a retromandibular position after postoperative treatment in comparison with the SSRO group. This tendency of the IVRO group would contribute to the database for treatment planning and prediction.
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