Jörn Daniela, Kohorst Philipp, Besdo Silke, Rücker Martin, Stiesch Meike, Borchers Lothar
Scientific Assistant, Department of Prosthetic Dentistry and Biomedical Materials Science, Hannover Medical School, Hannover, Germany.
Associate Professor, Department of Prosthetic Dentistry and Biomedical Materials Science, Hannover Medical School, Hannover, Germany.
J Prosthet Dent. 2014 Aug;112(2):340-8. doi: 10.1016/j.prosdent.2013.10.016. Epub 2014 Feb 14.
Loosening or fracture of the abutment screw are frequent complications in implant dentistry and are detrimental to the long-term success of the restorations. However, little is known about the factors influencing the stability of the screw-abutment complex.
The purpose of this study was to investigate the influence of lubricant action during implant assembly on screw preload and stresses in a dental implant-abutment complex.
A dental implant was modeled for finite element stress analysis. Different friction coefficients (μ=0.2 to 0.5) were chosen for the interfaces between implant components to simulate lubricant action or dry conditions. The stress analyses were each divided into 2 load steps. First, the abutment screw was virtually tightened with a torque of 25 Ncm. This was achieved by applying an equivalent preload calculated according to the different friction coefficients chosen. Second, the construction was externally loaded with a force of 200 N inclined by 30 degrees relative to the implant axis.
The screw preload increased with the decreasing friction coefficient. In all components, stresses increased with decreasing friction coefficient. Plastic deformation was observed at the implant neck in an area that expanded with decreasing friction coefficient. No plastic deformation occurred in the abutment.
The results of this study indicated that screw preload should be included in the finite element analysis of dental implants for a realistic evaluation of stresses in the implant-abutment complex. The friction coefficient significantly influenced the screw preload value and modified the stresses in the implant-abutment complex.
基台螺丝松动或折断是种植义齿常见的并发症，对修复体的长期成功有不利影响。然而，关于影响螺丝 - 基台复合体稳定性的因素却知之甚少。
本研究的目的是调查种植体组装过程中润滑剂作用对牙种植体 - 基台复合体中螺丝预紧力和应力的影响。
建立一个用于有限元应力分析的牙种植体模型。为种植体部件之间的界面选择不同的摩擦系数（μ = 0.2至0.5），以模拟润滑剂作用或干燥条件。应力分析均分为2个加载步骤。首先，虚拟地以25 Ncm的扭矩拧紧基台螺丝。这是通过根据所选不同摩擦系数计算施加等效预紧力来实现的。其次，对结构施加一个200 N的外力，该力相对于种植体长轴倾斜30度。
螺丝预紧力随着摩擦系数的降低而增加。在所有部件中，应力随着摩擦系数的降低而增加。在种植体颈部观察到塑性变形，该区域随着摩擦系数的降低而扩大。基台中未发生塑性变形。
本研究结果表明，在对牙种植体进行有限元分析以实际评估种植体 - 基台复合体中的应力时，应包括螺丝预紧力。摩擦系数显著影响螺丝预紧力值，并改变种植体 - 基台复合体中的应力。
