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目的:对临床中设计减数第一或第二磨牙矫治的病例进行调查,观察关闭间隙后相邻后牙根平行度情况。方法:选择病例41例,男10例,女31例,初诊年龄平均21岁,矫治结束时年龄平均23岁,所有病例均采用直丝弓矫治器矫治。分别对矫治前(T1)、矫治结束(T2)的拔牙间隙相邻后牙根平行度测量值进行分析。结果:减数第一磨牙矫治病例除下颌第二磨牙与第二前磨牙牙轴夹角及下颌第三磨牙与第二前磨牙牙轴夹角差别无显著性以外,其余测量项目均有显著性差异;减数第二磨牙矫治病例除上颌第一磨牙牙轴倾斜度及下颌第三磨牙与第一磨牙牙轴夹角无显著性差别外,其余测量项目均有显著性差异。说明第一或第二磨牙拔牙间隙关闭后上颌后牙不易达到根平行,下颌后牙容易达到根平行。结论:减数第一或第二磨牙的矫治方法可以实现下颌拔牙间隙相邻后牙的根平行,但对于上颌拔牙间隙两侧的牙齿很难实现根平行。原因主要是上颌后牙的牙根与上颌窦底的位置关系密切,对上颌后牙的牙根移动产生了阻碍。
OBJECTIVE: To investigate the cases of the first or second molars in clinical design and observe the parallelism of the adjacent posterior roots after closing the gap. Methods: 41 cases were selected, including 10 males and 31 females. The average age at diagnosis was 21 years. The average age was 23 years at the end of correction. All cases were treated with straight wire appliance. The measured values of root parallelism of adjacent tooth extraction gaps before and after the treatment (T1) and T2 (T2) were analyzed respectively. Results: There was no significant difference between the mandibular second molars and the second premolar teeth and the angle between mandibular third molars and the second premolar teeth in the first molar treatment cases There was significant difference in the measurement items except for the inclination of the first molar and the angle between the mandibular third molar and the first molar. Description of the first or second molar tooth extraction gap closure of the maxillary posterior teeth is not easy to reach parallel roots, mandibular posterior teeth easily reach the root parallel. Conclusion: The treatment of the first or second molars can realize the parallel roots of the adjacent posterior teeth of the mandibular extraction space, but it is very difficult for the roots to be parallel to the teeth on both sides of the maxillary extraction space. The main reason is the root of the maxillary posterior teeth and the position of the maxillary sinus closely, the root movement of the maxillary posterior teeth impeded.