关键词: 骨性Ⅱ类错牙合畸形, 高角, 成年女性, 拔牙, 头影测量

Abstract: Objective    To explore the soft and hard tissue factors that affect the change of chin protrusion and the change rule of hard tissue before and after treatment in adult female patients with skeletal class Ⅱ high-angle malocclusion who have completed tooth extraction camouflage therapy，and to provide reference for the efficacy evaluation and treatment design. Methods    A total of 48 adult female patients with skeletal class Ⅱ high-angle malocclusion who had completed tooth extraction camouflage therapy were selected. According to the sagittal change of the pogonion of soft tissue（Pos）on the lateral radiographs before and after treatment，the samples were divided into Pos backward shift group and Pos forward shift group. Measure the dental and skeletal indexes of the two groups and compare the differences of each index between the two groups before treatment，as well as the changes of hard tissue index before and after treatment in each groups. Results    Before treatment，the sagittal position of mandibular central incisors（L1-H），the mesial and distal inclination of mandibular first permanent molars（L6-MP），the sagittal position of upper，lower lips and soft chin（UL-H，LL-H，Pos-H）were significantly different between the two groups（P < 0.05）.There were significant differences in the sagittal position relationship of maxilla and mandible（ANB），the mandibular plane angle（MP-SN），the sagittal position of upper and lower central incisors and first permanent molars（U1-H，L1-H，U6-H，L6-H），the labial and lingual torque of upper and lower central incisors（U1-SN，L1-MP），the mesial-distal inclination of mandibular first permanent molars（L6-MP），and the vertical position of upper central incisors，upper first permanent molars and the mesiobuccal cusp of lower first permanent molars（U1-V′，U6d-V′，U6m-V′，L6m-V′）in Pos-forward group before and after treatment，while there were no significant differences in the upper and lower alveolar angle（SNA，SNB） or the mesial-distal inclination of maxillary first permanent molars（U6-SN）（P > 0.05）. There were significant differences in SNA，SNB，U1-H，L1-H，U1-SN，L1-MP，U6-MP，L6-MP and U1-V′ of the Pos-backword group before and after treatment（P < 0.05），while there were no significant differences in ANB，MP-SN，U6-H or L6-H（P > 0.05）. Conclusion    For adult female patients with skeletal class Ⅱ high-angle malocclusion，with more protruding lower central incisors，lips and soft tissue chin，and more mesial inclination of mandibular first permanent molars，it may be more difficult to obtain absolutely forward soft chin through orthodontic camouflage therapy. The orthodontic camouflage therapy may obtain the absolute forward soft tissue chin，so as to improve the patients′profile by controlling more carefully the amount of the anterior teeth retraction，mesially movement of the molars，the torque of the anterior teeth，the mesio-distal inclination of the molars and the amount of the anterior and posterior teeth intrusion.

Key words: skeletal class Ⅱ malocclusion, high angle, adult female, tooth extraction, cephalometry