摘要目的 探讨青春前期骨性Ⅲ类开<牙合>畸形患者的正畸治疗的机械性原理.方法 8例替牙期骨性Ⅲ类开<牙合>畸形患者,年龄7～9岁,平均(7.9±0.8)岁.患者均为手术适应证但拒绝手术治疗.所有患者接受面罩前牵引、磨牙<牙合>垫、快速扩弓和固定矫治,结束后随访2年.矫治前后头颅侧位片进行头影测量分析比较.结果 患者获得咬合、功能和面容的全面改善,结果 稳定.与矫治前相比,上颌骨逆时针旋转(5.3±1.7)°(P<0.01),长度增加并前移;下颌骨体顺时针旋转(2.6±0.5)°(P<0.01),升支长度增加;下切牙舌倾(5.7±0.4)°(P<0.01),而面部生长方向维持不变.结论 利用牙颌面矫形治疗的机械原理,可以引导生长发育期的骨性Ⅲ类开<牙合>畸形患者的生长,获得稳定和美观的治疗效果.

abstractsObjective To analyze the mechanic basis of orthodontic correction of preadolescence skeletal class Ⅲ malocclusion combined with open bite, and to summarize helpful experiences for clinical practice. Methods There were 8 preadolescent patients with severe skeletal class Ⅲ malocclusion combined with open bite [age ranged from 7 to 9 years, mean (7.9±0.8) years]. All the patients had indication of orthognathic surgery, but rejected surgical therapy. The patients received face mask traction, rapid maxillary expand, molar occlusal splint and fix appliance treatment, and were followed up for two years after the treatment. Lateral cephalometric films performed at the beginning and end of treatment were compared using traditional cephalometric analysis. Results All the patients get remarkable and stable improvement in occlusion, oral function and facial aesthetic after the treatment. The changes included the anterior movement and (5.3±1.7)° anticlockwise rotation of the maxilla (P<0.01), (2.6±0.5)° downward-backward rotation of the mandible body (P<0.01) and increase of mandible ramus length, and (5.7±0.4)° inclination of lower incisors when measured to the NB line (P<0.01). Meanwhile, the direction of the facial growth was maintained. Conclusion With the most of mechanic basis of dento-maxillofacial orthopedics, the facial growth direction of the patients with skeletal class Ⅲ malocclusion combined with open bite can be guided, and stable and esthetics curative effect can be achieved.