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目的:观察安氏Ⅱ1类错患者拔牙矫治后牙弓形态的变化规律,为临床治疗该类畸形提供参考。方法:选择拔除4个第一前磨牙进行正畸治疗的安氏Ⅱ1错患者30例,取矫治前后石膏模型,通过三维扫描生成数字化牙颌模型,同时建立计算机牙弓形态定量分析系统,通过定位标志点,在牙弓形态分析平面上获取各个牙位的坐标数据,利用三次方程式拟合牙弓曲线,测量牙弓宽度及长度的变化,量化牙弓形态的变化。结果:安氏Ⅱ1类错经过拔牙矫治后,①上颌侧切牙区以及尖牙区牙弓宽度明显增加(P<0.01,P<0.05),下颌侧切牙区和尖牙区牙弓宽度无明显变化;②上、下颌前磨牙区及磨牙区牙弓宽度明显减小(P<0.001);③矫治后上、下颌尖牙区长度明显增加(P<0.05),磨牙区长度明显减小(P<0.001)。结论:安氏Ⅱ1类错拔牙矫治后,上颌前部牙弓变宽,后部牙弓变窄,下颌前部牙弓形态未见明显缩窄。
OBJECTIVE: To observe the changes of dental arch morphology in patients with Class Ⅱ 1 malocclusion after tooth extraction, so as to provide reference for clinical treatment of such deformities. Methods: Thirty patients with Angle Ⅱ 1 malocclusion who underwent orthodontic treatment for removal of four first premolar teeth were enrolled in this study. Before and after orthodontic treatment, plaster models were obtained and digitized dental implants were generated by three-dimensional scanning. Meanwhile, a quantitative analysis system of dental arch morphology was established. The data of each dental position were obtained on the dental arch morphological analysis plane. The dental arch curve was fitted by cubic equation, the changes of dental arch width and length were measured, and the change of dental arch morphology was quantified. Results: After Class Ⅱ1 malocclusion, the arch width of the maxillary lateral incisor area and canine area increased significantly (P <0.01, P <0.05), while the arch width of mandibular lateral incisor area and canine area had no significant difference (P <0.001); (3) The length of the canine area was significantly increased (P <0.05) and the length of the molar area was significantly reduced (P < <0.001). Conclusion: After class Ⅱ1 malocclusion, the arch of the anterior maxilla broadens and the arch of the posterior arch narrows. There is no constriction of the arch of the anterior mandibular arch.