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目的:探讨安氏II类1分类患者单颌拔牙与双颌拔牙正畸治疗对下颌第三磨牙(M3)萌出的影响。方法:选取安氏II类1分类65例,上颌单颌前磨牙减数32例,双颌前磨牙减数33例。在治疗前后拍摄CBCT,NNT viewer中3D重建,测量M3的轴倾角度(LM3)和下颌第二磨牙(M2)远中间隙,以及M2之间、M3之间的宽度,治疗前后数据进行配对t检验。结果:单颌拔牙组左LM3增加(P<0.01);双颌拔牙组右LM3减少(P<0.01),M2远中间隙增加(P<0.001),M3间距减少(P<0.001)。结论:单颌拔牙可能会增加M3阻生机率;双颌拔牙可能会增加M3正常萌出机率。
Objective: To investigate the effects of single-jaw and double-jaw orthodontic treatment on the eruption of mandibular third molars (M3) in Angle II class 1 patients. Methods: Sixty - five cases of Class Ⅱ division 1 malocclusion were selected, including 32 cases of maxillary single premolars and 33 cases of bilateral premolar molar. CBCT was taken before and after treatment and 3D reconstruction was performed in NNT viewer. The axial inclination (LM3) of M3 and the distal mid-second molar (M2) were measured, and the widths between M2 and M3 were measured. The data before and after treatment were paired t test. Results: Left LM3 was increased in single maxillary extraction group (P <0.01). Left LM3 in bipolar extraction group was decreased (P <0.01), M2 distal gap was increased (P <0.001), M3 distance was decreased (P <0.001). Conclusion: Single maxillary extraction may increase the chances of M3 occlusion. Bilateral extraction may increase the normal eruption rate of M3.