无托槽隐形矫治器内收前牙时后牙移动趋势及牙周膜应力分布

Study on movement trend of posterior teeth and distribution of periodontal membrane stress during adduction

目的 :利用三维数字化技术对无托槽隐形矫治器内收前牙时后牙移动趋势及牙周膜应力分布进行分析。方法 :选择广西壮族自治区人民医院2017年6月—2022年6月收治的88例患者CBCT数据,将其输入Mimics 20.0软件中,对其各部位进行初步抽取,使用STL文件进行存储。通过Geomagic Studio 2014软件进行修补和优化,在优化基础上,构建无托槽隐形矫治器和牙周膜模型。利用Ansys Workbench19.0 FEM软件对6个FEM模型进行模拟仿真与观测,分析当前牙整体回收时,不同组别患者支抗牙的初始移动趋势与牙周膜范式等效应力分布。采用SPSS 21.0软件包对数据进行统计学分析。结果:所有患者支抗牙均发生不同程度牙根部颊向移动等倾向,其中,第二前磨牙位置移动在近中咬合方向上表现最为明显;而水平矩形附件组与垂直矩形附件组成相对关系,牙周膜最大范式等效应力大范围分布于牙颈部,接着是根尖区,以NA组支抗牙的范式等效应力值最大。附件垂直矩形组中,所有患者牙周膜最大范式等效应力值显著小于水平矩形组。结论:正畸牙附件设计对前牙回收时的位置移动具有较强抑制作用,在一定程度上提升了牙三维方向移动的精确性。无托槽隐形矫治器应用初期,患者牙周膜受到的范式等效应力较大。

PURPOSE:The movement trend of the posterior teeth and the distribution of the periodontal membrane stress were studied by using three-dimensional digital technology.METHODS:CBCT data of 88 patients admitted to our hospital from June 2017 to June 2022 were selected,and input into Mimics20.0 software for preliminary extraction of all parts and stored with STL files;then the data were repaired and optimized through Geomagic Studio 2014 software.With the help of normal phase extension,the invisible appliance and periodontal membrane were constructed.Finally,the six FEM models were simulated and observed by the current teeth in different groups.Statistical analysis was performed with SPSS 21.0 software package.RESULTS:The effect force of the largest periodontal membrane was distributed in the neck of the tooth,followed by the apical area,with the maximum effect force value in the NA group.In all accessory groups,the periodontal membrane maximum paradigm isoeffect force values of all patients in the accessory vertical rectangular group were significantly smaller than the values obtained in the horizontal rectangular group.CONCLUSIONS:The design of orthodontic tooth accessories has a strong inhibition effect on the position movement of anterior teeth during recovery,which improves the accuracy of tooth three-dimensional movement to a certain extent.Meanwhile,the normal equivalent stress of the periodontal membrane of patients in the initial application of the invisible appliance without brackets is large.