双钥匙曲控制伴有牙槽骨丧失的前牙转矩生物力学分析

发布时间：2018-10-19 17:28

【摘要】：目的:1、通过建立双钥匙曲内收伴有牙槽骨丧失的上颌前牙的三维有限元模型,为本实验的后续生物力学分析奠定基础。2、通过结扎双钥匙曲顶部使前牙段弓丝形变,探讨不同程度形变的弓丝控制前牙转矩的效能,并分析该力系系统对伴有不同程度牙槽骨丧失的前牙牙周膜的影响。方法:1、选择一名个别正常牙合且牙周健康的志愿者,通过CBCT扫描获得上颌骨及上牙列的数据信息,利用软件调整阈值,提取牙颌各种组织结构的数据从而构建3D初步模型。经Geomagic Studio软件设定各组织材料属性,并分别将牙槽骨降低0mm、1mm、2mm、3mm获得伴有不同程度牙槽骨丧失的上颌前牙的三维有限元模型。2、结扎丝向远中加力打开远中曲,近远中钥匙曲顶部结扎丝连扎,可使得前牙段弓丝平面与牙合平面成1°、3°、5°、7°,分别将弓丝作用于牙槽骨降低0mm、1mm、2mm、3mm的上颌骨和牙列的模型中,利用三维有限元法模拟整体内收上颌前牙,分析前牙相对移动趋势及牙周膜应力变化趋势。结果:1、本研究建立的上颌骨、上颌全牙列、双钥匙曲三维有限模型精确度较高,几何相似性好。2、前牙在双钥匙曲作用下均发生倾斜移动,尖牙倾斜度最大。3、近远中钥匙曲顶部结扎加力越大,在各工况矢状向上前牙牙冠舌倾趋势均减弱,垂直向伸长相对位移量减少。4、没有发生骨吸收的情况下,侧切牙随双钥匙曲形变程度增大而发生压入运动,其余工况,侧切牙发生伸长移动。5、尖牙在双钥匙曲内收前牙时,发生了扭转,且其三维方向上发生的相对位移在三个前牙中最大。6、随着牙槽骨降低,相同加载力值下前牙牙冠及牙根运动趋势均相应增大,前牙伸长趋势及根舌向转矩运动趋势增加,骨吸收1mm时尖牙牙周膜等效应力达3.01E-02MPa,而骨吸收达3mm时侧切牙处牙周膜等效应力达3.41E-02MPa,均超过牙周膜生理极限。结论:1、作为连续唇弓,双钥匙曲产生的力影响牙弓每一颗牙,近远中钥匙曲结扎加力,均能增加前牙整体内收时牙冠唇向转矩,加力的程度越大,冠唇向转矩的趋势也越明显。转矩增加的同时,牙颈部牙周膜应力增大。2、双钥匙曲对切牙的控制效果优于尖牙。3、随着牙槽骨降低,相同加载力值下的前牙牙冠及牙根运动趋势相应增大,前牙伸长趋势及根舌向转矩运动趋势增加。牙槽骨降低一定程度时,前牙牙周膜等效应力超过生理极限,可能会引起牙周组织进一步丧失。
[Abstract]:Objective: 1. To establish a three-dimensional finite element model of maxillary anterior teeth with alveolar bone loss in double key curvature, and to lay the foundation for further biomechanical analysis of the experiment. 2. To deform the arch wire of anterior segment by ligating the top of double key curve. To investigate the effect of different deformed arch wires on the torque control of anterior teeth, and to analyze the effect of the force system on the periodontal membrane of anterior teeth with different degrees of alveolar bone loss. Methods: 1. An individual volunteer with normal occlusion and periodontal health was selected, and the data of maxilla and upper dentition were obtained by CBCT scan, and the data of various tissue structures of dentin were extracted by software adjusting threshold to construct 3D preliminary model. The material properties of each tissue were set up by Geomagic Studio software, and the alveolar bone was reduced by 0 mm to 1 mm and 2 mm to 3 mm respectively to obtain the three-dimensional finite element model of maxillary anterior teeth with different degrees of alveolar bone loss. 2, the ligation wire was applied to the distal center to open the distal curve, and the three dimensional finite element model of the maxillary anterior teeth with different degrees of alveolar bone loss was obtained. The ligation of wire at the top of the proximal key bend can make the plane of anterior arch wire and occlusal plane become 1 掳, 3 掳, 5 掳and 7 掳respectively. The arch wire acts on the maxillary bone and dentition model with the alveolar bone reduced by 0 mm to 1 mm and 2 mm to 3 mm, respectively. The three-dimensional finite element method is used to simulate the whole maxillary anterior teeth. The relative movement trend of anterior teeth and the change trend of periodontal ligament stress were analyzed. Results: 1. The 3D finite model of maxilla, maxillary total dentition, double key curved 3D finite model established in this study has high accuracy and good geometric similarity. 2. The anterior teeth are inclined to move under the action of double key curvature. The canine inclination was the largest. 3. The greater the ligation force at the top of the proximal middle key curve, the lower the tendency of sagittal upward anterior crown and tongue inclination, the lower the relative displacement of vertical elongation, and the less bone resorption. The lateral incisors were pressed into the teeth with the increase of the deformation degree of the double keys. In other cases, the lateral incisors were elongated and moved. 5. When the canine teeth received the anterior teeth in the double key curvature, the torsion occurred. The relative displacement in the three dimensional direction was the largest in the three anterior teeth. 6. With the reduction of alveolar bone, the movement trend of the crown and root of the anterior teeth increased correspondingly under the same loading force, and the trend of the extension of the anterior teeth and the movement trend of the root tongue torque increased. When bone resorbed to 1mm, the isogenic force of periodontal membrane reached 3.01E-02MPa, while that of lateral incisor reached 3.41E-02MPa when bone resorption reached 3mm, which exceeded the physiological limit of periodontal ligament. Conclusion: 1. As a continuous labial arch, the force produced by double key curvature affects every tooth of dental arch, and the ligation force in the near and far distance can increase the crown lip torque when the whole anterior tooth is in adduction. The greater the degree of applied force is, the more obvious the trend of crown lip torque is. With the increase of torque, the stress of periodontal membrane in the neck of tooth increased. 2. The control effect of double key bend on incisor was better than that of canine. 3. With the decrease of alveolar bone, the movement trend of anterior crown and root increased with the same loading force. The trend of anterior tooth elongation and the movement of root tongue torque increased. When alveolar bone decreases to a certain extent, the effect force of anterior periodontal ligament exceeds the physiological limit, which may cause further loss of periodontal tissue.
【学位授予单位】：广州医科大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：R783.5

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