种植体数目与分布对下颌种植覆盖义齿骨组织应力变化的影响

目的：建立下颌种植覆盖义齿三维有限元模型，研究咬合力作用下种植体数目与位置分布对牙槽骨组织应力分布的影响因素。方法：临床采集患者下颌骨及其原有义齿CT数据，使用逆向工程软件建立种植体数目与位置不同的下颌种植覆盖义齿实体模型。通过Abaqus有限元软件分析咬合力作用下种植体数目与位置分布对种植体周围以及下颌后端牙槽骨应力变化的影响。结果：在咬合力作用下，下颌骨Mises应力主要分布在种植体周围骨组织，种植体远中颈部呈现应力集中，下颌后端区域应力较小且分布均匀。随着种植体数目的增加，后端种植体周围骨应力上升，远端牙槽骨应力降低。当牙弓前、后端种植体距离增加时，种植体周围骨应力增大，远端牙槽骨应力降低。结论：采用2植体支持的下颌种植覆盖义齿种植体周围骨吸收风险较小，但远端牙槽嵴骨吸收风险增大。4植体义齿所承受的咬合力主要由植体承担，修复时应注意前后植体的距离和咬合力在义齿上的合理分布。

Influence of implant number and location on the bone stress variation of mandibular implant supported over- dentures.

Objective：The objective of this study was to establish 3D FE model of mandibular implant overdenture,and investigate the stress distribution in alveolar bone induced by the implant number and location under bite force. Method：The CT data of mandible and denture from a patient were collected. Then reverse engineer softwares were used to construct mandibular overdenture supported by implant with different numbers and locations. The stress changes in peri-implant alve- olar bone and distal mandible were investigated to analyze the influence of implant numbers and locations on the change of stress in these areas under bite force. Result： The Mises stress mainly distributed around the implants in the alveolar bone, and was concentrated at distal neck of implant in the alveolar bone under the bite force. The stress in distal mandible were well distributed. With the increasing of implant number, stress increased in peri-implant bone of distal implants ,but de- creased in distal mandible. With the increasing of A-P distance,the stress increased in peri-implant bone,but decreased in distal mandible. Conclusion： The risk of bone resroption was lower in peri-implant bone in two implants supported overden- ture,but the risk of bone resorption in distal mandible was higher. When the overdenture was supported by 4 implants,occlu- sion force was mainly shared by implants. More attention should be paid on different A-P distance and well distribution of stress.