Abstract:

Objective　The alveolar bone thickness of maxillary central incisors was studied by CBCT in adults patients of Class Ⅱ division 1 and division 2 and the people with normal occlusion in order to provide reference for orthodontic clinical tooth movement. Methods　The sample consisted of 20 normal occlusion and 40 patients with Angle Class Ⅱmalocclusion（20 division 1 malocclusion patients and 20 division 2 malocclusion patients）. The alveolar bone  morphology of the maxillary central incisor was evaluated through using CBCT to measure the alveolar bone thickness in labial side，lingual side and in total， ∠U1-SN and ∠U1-PP，and the results were statistically analyzed. Results　（1）The thickness of alveolar bone in the apical labial alveolar bone of division 2 was smaller than that of division 1 and normal occlusion. （2）Alveolar bone thickness of the apical lingual side：division 2 > normal occlusion > division 1.（3）Total alveolar bone thickness：division 1 was smaller than that of the other two groups. （4）In Class Ⅱ，the labial inclination of maxillary central incisor increased，labial alveolar bone thickness increased，lingual alveolar bone thickness  decreased，and the total thickness decreased. Conclusion　In order to prevent the occurrence of iatrogenic alveolar bone defect，the best treatment should be made in combination with alveolar bone thickness for patients with Class Ⅱmalocclusion.

Key words: cone-beam CT, ClassⅡdivision 1, ClassⅡdivision 2, thickness of alveolar bone, incisor inclination

摘要：

目的　运用锥形束CT（CBCT）对比安氏Ⅱ类1分类和2分类成人患者与正常牙合成人上颌中切牙根尖区牙槽骨厚度，为正畸牙齿移动提供参考。方法　选取2017年2月至2018年10月就诊于山西医科大学第一医院正畸科的安氏Ⅱ类1分类、安氏Ⅱ类2分类成人患者各20例，另选取个别正常牙合成人20名，每位研究对象均拍摄CBCT。分别测量各分组研究对象的左、右上颌中切牙倾斜度∠U1-SN和∠U1-PP，上颌中切牙根尖区唇侧牙槽骨厚度、舌侧牙槽骨厚度及牙槽骨总厚度，将测量结果进行统计分析。 结果　（1）上颌中切牙根尖区唇侧牙槽骨厚度：安氏Ⅱ类2分类组小于安氏Ⅱ类1分类组和正常牙合牙合组；（2）上颌中切牙根尖区舌侧牙槽骨厚度：安氏Ⅱ类2分类组>正常牙合组>安氏Ⅱ类1分类组；（3）上颌中切牙根尖区牙槽骨总厚度：安氏Ⅱ类1分类组小于安氏Ⅱ类2分类组和正常牙合组；（4）安氏Ⅱ类错牙合，上颌中切牙唇倾度增大，根尖区唇侧牙槽骨厚度增加、舌侧牙槽骨厚度减小、牙槽骨总厚度减小。结论　对于安氏Ⅱ类错牙合患者的治疗，应结合牙槽骨厚度制定最佳矫治方案，以防止出现医源性牙槽骨缺损。

关键词: CBCT, 安氏Ⅱ类1分类, 安氏Ⅱ类2分类, 牙槽骨厚度, 切牙唇倾度