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首页> 外文期刊>The Journal of Prosthetic Dentistry >The dynamic natures of implant loading.
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The dynamic natures of implant loading.

机译：植入物加载的动态特性。

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STATEMENT OF PROBLEM: A fundamental problem in fully understanding the dynamic nature of implant loading is the confusion that exists regarding the torque load delivered to the implant complex, the initial force transformation/stress/strain developed within the system during the implant complex assembly, and how the clamping forces at the interfaces and the preload stress impact the implant prior to any external loading. PURPOSE: The purpose of this study was to create an accurately dimensioned finite element model with spiral threads and threaded bores included in the implant complex, positioned in a bone model, and to determine the magnitude and distribution of the force transformation/stress/strain patterns developed in the modeled implant system and bone and, thus, provide the foundational data for the study of the dynamic loading of dental implants prior to any external loading. MATERIAL AND METHODS: An implant (Branemark Mark III), abutment (CeraOne), abutment screw (Unigrip), and the bone surrounding the implant were modeled using HyperMesh software. The threaded interfaces between screw/implant and implant/bone were designed as a spiral thread helix assigned with specific coefficient of friction values. Assembly simulation using ABAQUS and LS-DYNA was accomplished by applying a 32-Ncm horizontal torque load on the abutment screw (Step 1), then decreasing the torque load to 0 Ncm to simulate the wrench removal (Step 2). The postscript data were collected and reviewed by HyperMesh. A regression analysis was used to depict the relationships between the torque load and the mechanical parameters. RESULTS: During the 32-Ncm tightening sequence, the abutment screw elongated 13.3 mum. The tightening torque generated a 554-N clamping force at the abutment/implant interface and a 522-N preload. The von Mises stress values were 248 MPa in the abutment at the abutment-implant interface, 765 MPa at the top of the screw shaft, 694 MPa at the bottom of the screw shaft, 1365 MPa in the top screw thread, and 21 MPa in the bone at the top of the implant-bone interface. This study also identified various characteristic isosurface stress patterns. The maximum stress magnitude to complete the von Mises stress joint pattern in the present model was 107 MPa during screw tightening, and was reduced to 104 MPa with removal of the wrench. Various specific stress patterns were identified within all elements of the implant complex during the assembly simulation. CONCLUSIONS: During the torque moment application, the abutment screw was elongated, and every 1.0-mum elongation of the screw was equivalent to a 47.9-N increase of the preload in the implant complex. The ideal index to determine the preload amount was the contact force at the interface between the screw threads and the threaded screw bore. The isosurface mode identified various characteristic stress patterns developed within the implant complex at the various interfaces during the assembly simulation. These patterns are the (1) spiral and ying-yang pattern of the XY stress, (2) spring, cap, clamping, and preload pattern of the ZZ stress, and (3) bone holding and joint pattern of the von Mises stress.
机译：问题陈述：充分了解植入物负载的动态性质的一个基本问题是，在传递至植入物复合体的扭矩负载，在植入物复合体组装过程中系统内部产生的初始力转换/应力/应变方面存在困惑。在任何外部加载之前，界面处的夹紧力和预加载应力如何影响植入物。目的：本研究的目的是创建一个尺寸精确的有限元模型，该模型的种植体中包含螺旋线和螺纹孔，并将其放置在骨骼模型中，并确定力转换/应力/应变模式的大小和分布在模型化的种植体系统和骨骼中开发了牙齿，因此为研究任何外部负荷之前牙齿种植体的动态负荷提供了基础数据。材料和方法：使用HyperMesh软件对植入物（Branemark Mark III），基台（CeraOne），基台螺钉（Unigrip）和植入物周围的骨骼进行建模。螺钉/植入物与植入物/骨骼之间的螺纹接口被设计为具有特定摩擦系数值的螺旋螺纹螺旋。使用ABAQUS和LS-DYNA进行组装模拟是通过在基台螺丝上施加32-Ncm的水平扭矩载荷（步骤1），然后将扭矩载荷减小到0 Ncm来模拟扳手的拆卸（步骤2）。后记数据由HyperMesh收集和审查。回归分析用于描述扭矩负载和机械参数之间的关系。结果：在32 Ncm的拧紧过程中，基台螺丝拉长了13.3毫米。拧紧扭矩在基台/植入物界面产生554-N的夹紧力，并产生522-N的预紧力。 von Mises应力值在基台与种植体界面的基台中为248 MPa，在螺杆轴的顶部为765 MPa，在螺杆轴的底部为694 MPa，在顶部螺杆为1365 MPa，在轴上为21 MPa。骨骼位于植入物-骨骼界面的顶部。这项研究还确定了各种特征性的等值面应力模式。在本模型中，完成von Mises应力连接模式的最大应力大小在螺丝拧紧期间为107 MPa，并且在卸下扳手时降低到104 MPa。在组装模拟过程中，在植入物复合体的所有元件中确定了各种特定的应力模式。结论：在施加力矩的过程中，基台螺丝被拉长了，螺丝每增加1.0毫米伸长量就相当于植入复合体中预紧力增加了47.9牛顿。确定预加载量的理想指标是螺纹与螺纹孔之间的界面处的接触力。在组装模拟过程中，等值面模式确定了在植入物复合体内部各个界面处形成的各种特征应力模式。这些模式是（1）XY应力的螺旋形和鹰眼形;（2）ZZ应力的弹簧，帽形，夹紧和预紧模式;以及（3）骨固定和von Mises应力的关节形。

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