正畸治疗中磨牙的拔除和保留(五十一)——关闭第一或第二磨牙拔牙间隙后相邻后牙根平行度的研究

The study of root parallelism adjacent to the space after extraction of first or second molar

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 study root parallelism of adjacent to space after closing by investigation of cases which were treated with first or second molar extraction.Method：41 cases,10 males and 31 females,were selected whose mean age of before treatment were 21 years old,mean age of after treatment were 23 years old.All cases were treated with straight wire appliance.Respectively,measurement analysis of root parallelism adjacent to molar space was made in two period,before treatmen（tT1）,end of treatmen（tT2）.Result：After contrast of before and after treatment,measurement indexs of first molar extraction cases has significant difference except two cases,the angle of lower second molar and second premolar and the angle of lower third molar and second premolar.measurement indexs of second molar extraction cases has significant difference except two cases,the tilt axis of maxillary first molar and the angle of lower third molar and first molar.It demonstrated that maxillary posterior teeth after the closure of space is not easy to reach the root parallel while the mandibular posterior teeth is easy to reach the root parallel after first or second molar extraction.Conclusion：Our treatment methods of closing first or second molar extraction spaces can achieve root parallelism of mandibular posterior teeth adjacent to the space,but were difficult to achieve root parallelism of maxillary posterior teeth.The main reason was that location relationship of maxillary posterior teeth root and maxillary sinus floor was close which obstructed the movement of the maxillary posterior teeth root.