上颌前牙区不同种植修复体在不同咬合受力下的三维有限元分析

文题释义：口腔种植修复体：是一种以植入骨组织内的结构为基础来支持、固位上部牙修复体的缺牙修复方式，它包括种植体、固位螺丝、修复基台及上部修复体，故以上各结构良好的生物力学性能决定着种植修复体的长期稳定性。三维有限元分析：通过单元格划分将连续的模型划分为有限个单元，后期根据研究的需要赋予其不同的材料性能，模拟生物力学环境，计算其所受应力。自1980年运用于口腔医学研究以来，有限元法已涉口腔种植的各个领域，如通过三维有限元法分析螺纹形态、基台角度、植体类型、颈部设计等因素对种植修复体的影响，目前经过国内外学者的大量研究，三维有限元模型的精确度也已得到了较大提升。背景：在口腔种植修复治疗中，修复因素与咬合因素影响着植体内部结构及植体-骨界面处应力的分布，植体内部结构及植体-骨界面处应力分布是否平衡决定着种植体的长期寿命与周围骨质水平的稳定性。目的：探讨与分析二氧化锆全瓷冠与钴铬合金烤瓷冠修复体在3种咬合关系中对植体-骨界面处、种植体、修复基台、固位螺丝及修复体内部应力分布的影响。方法：参照1例上颌中切牙区行种植体植入修复患者的锥形束CT影像资料，运用Mimics17.0软件建立上颌中切牙种植修复体模型，分别构建二氧化锆全瓷冠与钴铬合金烤瓷冠两种三维有限元模型，模拟对刃合、正常合、深覆合3种咬合状况进行加载，分析在2种修复体与3种加载方式影响下种植体内部各结构与种植体-骨界面的应力分布情况。结果与结论：①在钴铬合金烤瓷冠组中，当咬合关系由对刃合转变为正常合及深覆合时，修复体咬合位点处应力相应增加，而修复基台、种植体边缘及植体-骨界面处的应力减小；正常咬合关系中固位螺丝处的应力较其他两种咬合方式更为集中，等效应力峰值更高。②在二氧化锆全瓷冠组中，当咬合关系由对刃合转变为正常合及深覆合时，修复基台、种植体及种植体-骨界面的应力峰值呈逐渐下降趋势；正常合时修复体咬合位点及固位螺丝处的应力峰值高于其他两种咬合关系。③对刃合时，钴铬合金烤瓷冠组修复体咬合位点处的等效应力峰值略高于二氧化锆全瓷冠组，修复基台、固位螺丝、种植体与种植体-骨界面的等效应力峰值略低于二氧化锆全瓷冠组；正常合时，钴铬合金烤瓷冠组种植体颈部处的等效应力峰值略高于二氧化锆全瓷冠组，修复体、修复基台、固位螺丝、种植体-骨界面的等效应力峰值略低于二氧化锆全瓷冠组；深覆合时，钴铬合金烤瓷冠组修复体咬合位点处及种植体颈部处的等效应力峰值均高于二氧化锆全瓷冠组，修复基台、固位螺丝、种植体-骨界面的等效应力峰值略低于二氧化锆全瓷冠组。④结果表明，咬合关系与上部修复体的不同影响着应力在种植修复体各结构及植体-骨界面的分布，此结论或许能为种植修复体远期并发症的预测提供参考依据。ORCID: 0000-0001-8522-5337(安尼卡尔•安尼瓦尔)中国组织工程研究杂志出版内容重点：生物材料；骨生物材料; 口腔生物材料; 纳米材料; 缓释材料; 材料相容性；组织工程

Three-dimensional finite element analysis of different implant prostheses in maxillary anterior teeth region under different occlusal relationships

BACKGROUND: In the treatment with dental implant prosthesis, the stress distribution of marginal bone and implant-bone interface is affected by the factors of restoration and occlusion. The internal structure and the stress distribution of implant-bone interface determine the long-term life of the implant and the stability of the marginal bone. OBJECTIVE: To analyze the effects of zirconia-based all-ceramic crown and Co-Cr alloy porcelain ceramic crown on the stress distribution of implant-bone interface, implant, prosthesis abutment, retention screw, and the inner structure in three occlusal relationships. METHODS: Using Mimics 17.0 software, the implant model of maxillary central incisor was established based on the cone beam CT of a patient undergoing prosthesis implantation into the maxillary central incisor. Two kinds of three-dimensional finite element models of zirconia-based all-ceramic crown and Co-Cr alloy porcelain ceramic crown were constructed. The edge to edge occlusion, normal occlusion and deep overbite were simulated to analyze the stress distribution of implant structure and the implant-bone interface in the three occlusal relationships. RESULTS AND CONCLUSION:(1) In the Co-Cr alloy porcelain ceramic crown group, when the occlusal relationship changed from the edge-to-edge occlusion to the normal occlusion and deep overbite relationships, the stress at the occlusal point of the prosthesis increased correspondingly, and the stress at the abutment, implant and the implant-bone interface decreased. In the normal occlusal relationship, the stress at the retention screw was more concentrated than that in the other two occlusal relationships, and its peak value of the equivalent stress was higher.(2) In the zirconia-based all-ceramic crown group, when the occlusal relationship changed from edge-to-edge occlusion to the normal and deep overbite relationships, the stress peaks of the abutment, implant and implant-bone interface decreased gradually. In the normal occlusal relationship, the stress peaks of the occlusal point and the retention screw were higher than those in the other two occlusal relationships.(3) In the edge-to-edge occlusion relationship, the peak of equivalent stress at the occlusal point of the implant prosthesis in the Co-Cr alloy porcelain ceramic crown group was slightly higher than that in the zirconia-based all-ceramic crown group. The peaks of equivalent stress of the abutment, retention screw, implant, and implant-bone interface in the Co-Cr alloy porcelain ceramic crown group were slightly lower than those in the zirconia-based all-ceramic crown group. In the normal occlusal relationship, the peak of equivalent stress at the neck of the implant in the Co-Cr alloy porcelain ceramic crown group was slightly higher than that in the zirconia-based all-ceramic crown group. In the deep overbite relationship, the peaks of the equivalent stress at the occlusal site of the implant prosthesis and the neck of the implant in the Co-Cr alloy porcelain ceramic crown group were higher than those in the zirconia-based all-ceramic crown group. The peaks of equivalent stress of the abutment, retention screw, and implant-bone interface in the Co-Cr alloy porcelain ceramic crown group were slightly lower than those in the zirconia-based all-ceramic crown group.(4) These results showed that different occlusal relationships and different upper structures of the implant prosthesis affected the stress distribution in each part of the implant and at the implant-bone interface. This finding may provide a reference for the prediction of long-term complications of implant prosthesis.