安氏II类1分类单双颌前磨牙减数对下颌第三磨牙影响的CBCT研究

Effect of Upper Jaw or Double Jaw Premolar Extraction of Class II Division I Malocclusion Patients on Mandibular Third Molar Eruption with Cone Beam CT Images

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 compare the effect of upper jaw or double jaw orthodontic extraction of Class II division I malocclusion patients on mandibular third molar （M3） eruption. Methods： Sixty--five patients with Class II division I malocclusion were chosen for orthodontic treatment, within upper jaw premolars extraction in 32 cases and double jaw premolars extraction in 33 cases. The Cone beam CT images were taken before and after treatment, 3D images were then created using Software NNT viewer. Measurements included the angle between the M3 axis and the man- dibular occlusal plan （LM3）, the mandibular second molar （M2） distal space, as well as the width between M2s and M3s. The data before and after treatment were analyzed by paired t test. Results.. In upper jaw extraction group, left LM3 increased （P〈0.01） ; while in double jaw extraction group, right LM3 reduced （P〈0.01）, the M2 distal space added （P〈0. 001）, and the width of M3s decreased （P〈0. 001）. Conclusion： Upper jaw extractions might increase the rate of M3 impaction; in contrast, double jaw extractions might enhance the rate of M3 normal erup- tion.