Yamamoto Taeko, Kaku Masato, Ono Shigehiro, Takechi Masaaki, Tanimoto Kotaro
Department of Orthodontics and Craniofacial Developmental Biology, Hiroshima University Graduate School of Biomedical Sciences.
Department of Anatomy and Functional Restorations, Division of Oral Health Sciences, Hiroshima University Graduate School of Biomedical Sciences.
Bull Tokyo Dent Coll. 2023 Jan 11;63(4):177-187. doi: 10.2209/tdcpublication.2022-0016. Epub 2022 Nov 15.
This report describes the treatment of severe skeletal Class II malocclusion in a young woman with a gummy smile and pronounced lower anterior facial height. Overjet and overbite were +12.0 mm and -1.0 mm, respectively. Cephalometric analysis revealed inferior positioning of the maxilla and severe mandibular retrusion with clockwise rotation. Both the upper and lower anterior teeth showed labial inclination. Based on a diagnosis of a skeletal Class II high angle with mandibular retrusion and a gummy smile, double-jaw orthognathic surgeries for upper and lower premolar extraction were chosen to gain ideal occlusion and an improvement in the esthetic facial profile. Le Fort I osteotomy was performed to move the anterior and posterior teeth upward by 4.0 mm and achieve mandibular counterclockwise rotation. Short lingual sagittal split ramus osteotomy was performed to move the mandible forward by 3.0 mm. As a result, normal overjet and overbite were achieved together with a straight profile and a good smile. After surgery, electromyographic evaluation of anterior temporal muscle activity showed an improvement in the percentage overlapping coefficient value (a symmetric index of bilateral muscle activity) from 28.1% to 63.2% compared to at pre-treatment. The pattern of jaw movement also showed an improvement. These results suggest that orthognathic surgery in skeletal Class II cases can improve not only malocclusion and the skeletal relationship of the jaws, but also masticatory function and jaw movement.
本报告描述了一名年轻女性严重骨性安氏II类错牙合畸形的治疗过程，该患者伴有露龈笑和明显的下前牙面部高度增加。覆盖和覆牙合分别为+12.0毫米和-1.0毫米。头影测量分析显示上颌位置较低，下颌严重后缩并伴有顺时针旋转。上下前牙均表现为唇倾。基于骨性安氏II类高角伴下颌后缩和露龈笑的诊断，选择上下颌前磨牙拔除的双颌正颌手术，以获得理想的咬合关系并改善面部美观轮廓。进行了Le Fort I型截骨术，将前后牙向上移动4.0毫米，并实现下颌逆时针旋转。进行了短的舌侧矢状劈开下颌升支截骨术，将下颌向前移动3.0毫米。结果，实现了正常的覆盖和覆牙合，同时面部轮廓变直，笑容良好。术后，对颞前肌前部活动的肌电图评估显示，与治疗前相比，重叠系数值（双侧肌肉活动的对称指数）从28.1%提高到了63.2%。下颌运动模式也有所改善。这些结果表明，骨性安氏II类病例的正颌手术不仅可以改善错牙合畸形和颌骨的骨骼关系，还可以改善咀嚼功能和下颌运动。
