Purpose: The purpose of this study is to use finite element analysis to predict the fatigue life of an implant system subjected to fatigue load by mastication (chewing force). The reliability and the stability of implant system can be defined in terms of the fatigue strength. Not only an implant is expensive but also it is almost impossible to correct after it is inserted. From a bio-engineering standpoint, the fatigue strength of the dental implant system must be evaluated by simulation (FEA). Material and Methods: Finite element analysis and fatigue test are performed to estimate the fatigue strength of the implant system. Mesh of implant is generated with the actual shape and size. In this paper, the fatigue strength of implant system is estimated: U-fit (T.Strong, Korea, internal type). The stress field in implant is calculated by elastic-plastic finite element analysis. The equivalent fatigue stress, considering the contact and preload stretching of a screw by torque for tightening an abutment, is obtained by means of Sine's method. To evaluate the reliability of the calculated fatigue strength, fatigue test is performed. Results: A comparison of the calculated fatigue strength with experimental data showed the validity and accuracy of the proposed method. The initiation points of the fatigue failure in the implant system exist in the region of high equivalent fatigue stress values. Conclusion: The above proposed method for fatigue life estimation can be applied to other configurations of the differently designed and improved implant. In order to prove reliability of prototype implant, fatigue test should be executed. The proposed method is economical for the prediction of fatigue life because fatigue testing, which is time consuming and precision-dependent, is not required.
Bioengineering ; Dental Implants ; Fatigue* ; Finite Element Analysis ; Korea ; Mastication ; Torque

Unruptured dural arteriovenous fistula (dAVF) manifests various symptoms including exophthalmos, headache, tinnitus, and retro-orbital pain. Transient global amnesia (TGA) is a clinical syndrome of reversible anterograde amnesia. Here, we report a 62-year-old woman with dAVF, manifested as TGA. This case emphasized that the clinicians should stay vigilance to the organic cause of TGA, especially in those complaining other symptoms besides amnesia such as pulsatile tinnitus and headache. Furthermore, our case supports a hypothetical patho-mechanism of venous congestion for TGA.