Objective:To correct mandibular prognathism with the technique of sagittal split ramus osteotomy(SSRO) and extraoral vertical ramus osteotomy(EVRO).
目的：应用粗裂钻和薄刃锐利骨凿施下颌骨升支垂直截骨术和矢状劈开截骨术治疗下颌骨前突畸形。
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Conclusions Of the patients with mandibular prognathism, 1. the hyoid bone shifted downward, the dorsum lingua raised and the base of the tongue moved posteriorly;