安氏Ⅱ类错■不同矫治模式对下颌第三磨牙萌出的影响

Influence of different extraction patterns on the eruption of mandibular third molars in patients with Class Ⅱ malocclusion

目的比较不同矫治模式下成人安氏Ⅱ类错牙合患者下颌第三磨牙萌出状况的变化,探讨不同治疗方式对下颌第三磨牙萌出的影响。方法选取90例成人安氏Ⅱ类错患者,分为不拔牙组(30例)、拔除第一前磨牙组(30例)和拔除第二前磨牙组(30例),矫治前后分别拍摄曲面体层片,测量下颌第三磨牙倾斜角度及萌出间隙,预测其萌出情况。结果与不拔牙组相比,拔牙组矫治前后下颌第三磨牙倾斜角度显著改善(P<0.05)。拔牙组矫治前后下颌第三磨牙萌出间隙明显增大(P<0.05)。3组间矫治前后萌出间隙变化具有统计学意义(P<0.001),非拔牙组下颌萌出间隙差值大于拔除第一前磨牙组,而拔除第一前磨牙大于拔除第二前磨牙组。预测拔除第二前磨牙组下颌第三磨牙萌出关系最好,其次是拔除第一前磨牙组,最后是非拔牙组。结论拔除下颌前磨牙利于矫治后第三磨牙倾斜角度及萌出间隙的改善,拔牙位置越靠后,其改善越显著,萌出概率也越大。

Objective To compare the changes in the angulation and eruption space of the mandibular third molars in adult patients with ClassⅡmalocclusion orthodontically treated with different extraction patterns, and to discuss the effects of different therapies on the eruption of mandibular third molars. Methods Ninety adult patients with ClassⅡmalocclusion were chosen, which were divided into three groups:non-extraction group(n=30);the first premolar extraction group(n=30);the second premolar retraction group(n=30). The panoramic radiographs were taken before and after treatment. The differences of the angulation and eruption space of the mandibular third molars were compared before and after treatment to predict its eruption. Results Compared with non-extraction group, the angulation and eruption space of mandibular third molars improved and increased significantly after treatment with the first and second premolar extraction groups(P<0.05). There were significant differences in the eruption space change among three groups(P<0.001). The difference of the eruption space between the non-extraction group was greater than that in the first premolar extraction group, and the first premolar extraction group was greater than that in the second premolar extraction group. The prediction of eruption of the mandibular third molar was the best in the second premolar extraction group, followed by the first premolar extraction group and then non-extraction group. Conclusion Mandibular first or second premolar extraction increases the angulation and eruption space of mandibular third molars. And the closer the third molar is to the extraction site, the more angulation and eruption space improve, the more likely it is to become erupted.