目的 ·利用锥形束 CT（cone-beam computed tomography，CBCT）比较上颌前牙倾斜性内收（ retraction adjunct with tip， R&Tp）和控根性内收（ retraction adjunct with torque，R&Tq）产生的牙槽骨改建反应差异。方法 ·选取 40例符合纳入标准的安氏Ⅱ类 1分类青少年患者，根据牙齿实际内收方式对纳入对象所有 160颗上颌切牙进行标准化分组（分为倾斜内收组和控根内收组），利用 CBCT影像结合三维测量软件对 2组牙齿内收情况以及相关牙槽骨高度和厚度变化进行测量分析和比较。结果 · 2组前牙均实现较大范围内收和直立，倾斜内收组牙冠内收距离及内收角度均明显大于控根内收组（均 P0.000）。倾斜内收组 L3、P1厚度显著减小（均 P0.000），控根内收组 P1、P2厚度显著减小（均 P0.000）。倾斜内收组 T1厚度减小（ P0.000），控根内收组各水平牙槽骨总厚度均减小（均 P0.000）。2组唇侧（ P0.000）、腭侧（ P0.000）牙槽嵴高度均下降，且腭侧牙槽嵴高度降低更显著。结论 ·安氏Ⅱ类 1分类青少年患者上颌前牙在较大范围内收时，倾斜内收组唇侧根尖区、腭侧牙槽嵴区以及控根内收组腭侧牙根颈部及中部区域均为牙槽骨吸收高风险区。

Objective · Using cone-beam computed tomography (CBCT) to compare alveolar bone changes in maxillary anterior area secondary to maxillary incisor retraction adjunct with tip (R&Tp) and retraction adjunct with torque (R&Tq) movements. Methods · Forty teenagers with Angles class Ⅱ division 1 malocclusion who had completed orthodontic treatment met the inclusion criteria and were selected, and all of their 160 maxillary incisors were classified into two categories, namely R&Tp group and R&Tq group, according to their actual retraction pattern. Pre- and post-treatment CBCT images and 3D measurement software were used to measure and analyze tooth retraction and alveolar bone height and thickness changes within each group and to compare treatment changes of teeth and alveolar bone between two groups. Results · Anterior teeth in each group were intensively retracted and uprighted, with a longer retraction distance of incisal edge and a greater retraction angle of teeth in R&Tp group than in R&Tq group (both P0.000). Alveolar bone thickness was significantly decreased at L3 and P1 in R&Tp group (both P<0.05), while it was significantly decreased at P1 and P2 in R&Tq group (both P<0.05). Total alveolar bone thickness decreased at T1 in R&Tp group (P0.000) and at all levels in R&Tq group (all P0.000). Finally, alveolar ridge height in two groups dropped both in the buccal (both P0.000) and palatal (both P0.000) sides, with a more prominent extent in the palatal side, and ridge height dropped most in palatal side of the teeth in R&Tq group. Conclusion · The buccal root apex area and the palatal alveolar ridge area of alveolar bone in the R&Tp group and the cervical and middle area of incisor root in palatal side of alveolar bone in the R&Tq group are high-risk areas for alveolar bone resorption when anterior teeth in teenagers with Angles class Ⅱ division 1 malocclusion are intended to have en masse retraction.