目的：应用锥束计算机体层摄影术（cone-beam computed tomography，CBCT）研究成年骨性Ⅱ类及Ⅲ类高角错牙合患者下切牙区牙槽骨形态的差异。方法：从2015年10月至2017年8月在北京大学口腔医院就诊并且拍摄了CBCT的患者中筛选出骨性Ⅱ类及Ⅲ类高角错牙合患者各31名，对患者下切牙区牙槽骨的高度、牙槽骨面积及牙槽骨厚度进行测量，并应用SPSS 17.0软件进行独立样本t检验分析。结果：两组相比，骨性Ⅲ类组患者的下切牙牙槽骨唇侧根尖区的牙槽骨面积及唇侧总牙槽骨面积均低于骨性Ⅱ类组患者，下切牙唇侧根尖处的牙槽骨厚度也低于骨性Ⅱ类组患者，差异有统计学意义（P<0.05）。骨性Ⅲ类组患者下切牙牙槽骨舌侧釉牙骨质界（cemento-enamel junction，CEJ）下6 mm处牙槽骨面积、舌侧根尖区及舌侧总牙槽骨面积均低于骨性Ⅱ类组患者。在下切牙牙槽骨舌侧CEJ下4 mm、6 mm以及舌侧根尖处的牙槽骨厚度，骨性Ⅲ类组患者也低于骨性Ⅱ类组患者，差异有统计学意义（P<0.05）。结论：骨性Ⅲ类高角错牙合患者下切牙区牙槽骨的面积及厚度在唇舌侧根尖区明显小于骨性Ⅱ类高角错牙合患者，在对其进行前牙的唇舌向移动时尤其要注意转矩的控制，以防止根吸收及骨开窗、骨开裂的发生。

Objective： To evaluate the difference of features of alveolar bone support under lower anterior teeth between high-angle adults with skeletal class Ⅱ malocclusions and high-angle adults presenting skeletal class Ⅲ malocclusions by using cone-beam computed tomography (CBCT). Methods: Patients who had taken the images of CBCT were selected from the Peking University School and Hospital of Stomatology between October 2015 and August 2017. The CBCT archives from 62 high-angle adult cases without orthodontic treatment were divided into two groups based on their sagittal jaw relationships: skeletal class Ⅱ and skeletal class Ⅲ. vertical bone level (VBL), alveolar bone area (ABA), and the width of alveolar bone were measured respectively at the 2 mm, 4 mm, 6 mm below the cemento-enamel junction (CEJ) level and at the apical level. After that, independent samples t-tests were conducted for statistical comparisons. Results: The ABA of the mandibular alveolar bone in the area of lower anterior teeth was significantly thinner in the patients of skeletal class Ⅲ than those of skeletal class Ⅱ, especially in terms of the apical ABA, total ABA on the labial and lingual sides and the ABA at 6 mm below CEJ level on the lingual side (P<0.05). The thickness of the alveolar bone of mandibular anterior teeth was significantly thinner in the subjects of skeletal class Ⅲ than those of skeletal class Ⅱ, especially regar-ding the apical level on the labial and lingual side and at the level of 4 mm, 6 mm below CEJ level on the lingual side (P<0.05). Conclusion: The ABA and the thickness of the alveolar bone of mandibular anterior teeth were significantly thinner in the group of skeletal class Ⅲ adult patients with highangle when compared with the sample of high-angle skeletal class Ⅱ adult cases. We recommend orthodontists to be more cautious in treatment of highangle skeletal class Ⅲ patients, especially pay attention to control the torque of lower anterior teeth during forward and backward movement, in case that the apical root might be absorbed or fenestration happen in the area of lower anterior teeth.