舌侧活动翼矫治技术内收下前牙的三维有限元分析

Three-dimensional finite element method analysis of mandibular anterior teeth retraction with lingual active-wing appliance

目的利用三维有限元模型分析舌侧活动翼矫治技术内收下前牙过程中牙列的位移趋势和牙周膜应力分布。方法利用志愿者的锥形束CT数据及舌侧活动翼托槽实体数据,建立排齐后的下颌牙列及矫治器的三维有限元模型,在此模型上施力内收下前牙,初步分析下牙列的初始位移特点以及牙周膜应力分布。结果加力后,下颌中切牙倾斜移动伴有压低;侧切牙、尖牙少量舌侧移动;第二前磨牙远中倾斜略有舌倾;第一磨牙比较稳定;第二磨牙整体略有近中倾斜,牙冠则表现为舌倾和远中舌向扭转;在内收时,应力主要集中于下颌中切牙,尤其是牙颈部和根尖部。结论舌侧活动翼矫治技术内收下前牙时对前牙压低的同时后牙支抗有一定保护作用,对牙弓形态有良好控制。

Objective To analyze the displacement trend of the dentition and the stress distribution of periodontal ligament during the retraction of the mandibular anterior teeth by the lingual active-wing appliance using three-dimensional finite element method(FEM).Methods The three-dimensional finite element model of mandibular dentition and appliance was established by using the Cone beam CT scan data of volunteers and the manufacturing data of lingual active wing brackets.The ligature force was applied to the model to retract the anterior teeth,and the initial displacement and the stress distribution of periodontal ligament of the mandibular dentition were analyzed.Results After stress,the mandibular central incisor had a tendency of lingual inclination and depression.The lateral incisor and canine moved slightly lingually.The second premolar tilted slightly distally and lingually.The first molar was stable.The second molar was slightly medially tilted,and the crown showed lingual tilting and distal lingual rotation.During retraction,the stress was mainly concentrated in the mandibular central incisor,especially at cervical and root region.Conclusions The lingual active-wing appliance technique has a certain protective effect on the anchorage of the posterior teeth while the anterior teeth are retracted,and the shape of the dental arch can be well controlled.