个性化舌侧矫治微种植体支抗近中移动下颌第二磨牙的三维有限元研究

发布时间：2018-02-20 02:05

本文关键词： 个性化舌侧矫治微种植体三维有限元生物力学磨牙前移　出处：《郑州大学》2017年硕士论文　论文类型：学位论文

【摘要】：目的建立包括个性化舌侧托槽、不锈钢弓丝、下牙列、牙周膜及牙槽骨在内,左侧第一磨牙缺失的下颌三维有限元模型,研究个性化舌侧矫治微种植体支抗近中移动下颌第二磨牙,牙齿移动规律及牙周膜应力分布特征,为临床应用提供参考。方法本研究设计为三个实验:实验一为三维有限元整体模型的建立,方法如下:256排螺旋CT扫描获取志愿者的下颌影像,通过Mimics、Pro/E、Geomagic Studio软件转化为下颌骨三维模型;建立3个不同槽沟长度(3.5mm、4.0mm、4.5mm)的左侧下颌第二磨牙个性化舌侧托槽;在ANSYS内将下颌骨与托槽模型组装成3个个性化舌侧托槽-不锈钢弓丝-下牙列-牙周膜-下颌骨的实体模型,最后对实体模型进行网格划分、材料力学参数设定、边界约束得到三维有限元模型。实验二:研究不同牵引力个性化舌侧矫治微种植体支抗近中移动下颌第二磨牙牙齿位移与牙周膜应力的变化规律。在槽沟长度为4.0mm的三维有限元模型上,设置四种工况。工况一为单纯舌侧加载1.5N(150g)拉力,工况二、三、四为分别在唇舌侧同时加载0.5N(50g)、0.75N(75g)、1.0N(100g)拉力,读取牙列三维方向的初始位移以及牙周膜von Mises应力、最大主应力及最小主应力分布情况并进行分析总结。实验三:研究不同槽沟长度个性化舌侧矫治微种植体支抗近中移动下颌第二磨牙牙齿位移与牙周膜应力的变化规律。分别对实验一建立的三个有限元模型唇舌侧同时加载拉力为0.75N,设置3种工况,读取与分析的指标与实验二相同。结果实验一成功建立3个第二磨牙槽沟长度不同,包括个性化舌侧托槽、不锈钢弓丝、下牙列、牙周膜、下颌骨在内的左侧第一磨牙缺失的下颌三维有限元模型。实验二研究发现唇舌侧同时加力比单纯舌侧加力下颌第二磨牙牙周膜应力分布更加均匀,减小了远中舌向扭转的趋势,增加了近中倾斜的趋势。随着拉力不断增加,近中倾斜趋势、牙齿的初始位移、牙周膜应力均增加,双侧分别加载1.0N的拉力牙周膜的von Mises应力最大值达到5.72×10-2Mpa,超过安全范围。实验三研究发现槽沟长度从3.5mm延长到4.5mm时,牙齿仍为倾斜移动,但牙周膜应力分布更加均匀。槽沟长度每延长0.5mm,牙冠与牙根的初始位移差减小5%。结论1.个性化舌侧矫治微种植体支抗近中移动下颌第二磨牙的三维有限元模型系首次构建,具有较强的临床相似性与生物仿真性,可以为进一步研究提供平台。2.在该模型下,最适宜前移下颌第二磨牙的加力方式为唇舌侧同时加载0.75N的力量。3.通过延长个性化舌侧托槽槽沟的长度可以降低牙齿前移时近中倾斜的趋势但效果十分有限,临床应用时还需配合其他正轴方法。
[Abstract]:Objective to establish a three-dimensional finite element model of the left first molar, including individual lingual bracket, stainless steel arch wire, lower dentition, periodontal ligament and alveolar bone. To study the characteristics of tooth movement and periodontal ligament stress distribution in the treatment of mandibular second molars with individualized lingual microimplant Anchorage. Methods this study was designed as three experiments: one was the establishment of a three-dimensional finite element model, and the methods were as follows: 256-slice spiral CT scan to obtain mandibular images of volunteers. Three dimensional mandibular models were transformed into three dimensional mandibular models by using the software of Mimicsl Prop / Geomagic Studio, and three individualized lingual brackets of left mandibular second molars with different grooves (3.5 mm or 4.0 mm to 4.5 mm) were established. In ANSYS, the mandibular and bracket models were assembled into three individual solid models of tongue side bracket, stainless steel arch wire, lower dentition, periodontal ligament and mandible. Finally, the solid model was meshed and the mechanical parameters of materials were set. Three dimensional finite element model was obtained by boundary constraint. Experiment 2: study the change of tooth displacement and periodontal membrane stress of mandibular second molars with different traction individualized tongue side orthodontic implants. The length of grooves is as follows:. On the 4.0mm 3D finite element model, Four kinds of working conditions were set up. The first condition was simple tongue side loading 1.5 Nu 150g) tension, and the second, third, and fourth conditions were 0.5 Nu 50Nm 0.75NL 75g ~ (75) N ~ (-1) N ~ (10) N ~ (100 g)) at the same time. The initial displacement of the three-dimensional direction of dentition and the von Mises stress of periodontal ligament were read. The distribution of maximum principal stress and minimum principal stress were analyzed and summarized. Experiment 3: study on the displacement and periodontal ligament stress of mandibular second molar treated with micro-implant support with different grooves. For the three finite element models established in experiment 1, the tension on the lip and tongue side is 0.75 N at the same time, and three kinds of working conditions are set up. Results in experiment 1, the length of the grooves of the three second molars were different, including the individualized lingual brackets, stainless steel arch wire, lower dentition, periodontal ligament, and so on. Three dimensional finite element model of the left first molar missing from the mandible. Experiment 2 found that the stress distribution of the periodontal membrane of the mandibular second molar was more uniform than that of the simple lingual side, which reduced the trend of the torsion of the distal tongue. With the increasing of tension and inclination, the initial displacement of teeth and the stress of periodontal membrane are all increased. The maximum von Mises stress of the tension periodontal membrane loaded with 1.0 N on both sides was 5.72 脳 10 ~ (-2) MPA, which exceeded the safe range. Experiment 3 showed that when the groove length was extended from 3.5 mm to 4.5 mm, the tooth was still tilted. However, the stress distribution of periodontal ligament is more uniform. The initial displacement difference between crown and root decreases by 5. 1. The three dimensional finite element model of individualized lingual microimplant Anchorage against proximal mandibular second molar is constructed for the first time. Has strong clinical similarity and biological simulation, can provide a platform for further research. 2. Under this model, The most suitable way to push forward mandibular second molars is to load 0.75N at the same time on the lip and tongue side. 3. By extending the length of the grooves of the individualized lingual side, we can reduce the tendency of the proximal and middle tilt of the teeth when the teeth move forward, but the effect is very limited. Other positive axis methods should also be used in clinical application.
【学位授予单位】：郑州大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：R783.5

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