| Summary: | 碩士 === 高雄醫學大學 === 牙醫學研究所碩士班 === 94 === In recent the applications of dental implants are becoming more and more prevalent. The problems related to the prosthesis of dental implants, therefore, had been noted because dental implants are more in the posterior area in which there were always loaded with high occlusion forces. The success of dental implants mainly depends on how much forces in the prosthesis can endure. Dentists and scholars had been working to obtain a high success rate of dental implants, since it was introduced.
Clinical studies have been reported that the significant bone loss around the implant neck of failing implants was found and various hypotheses have been proposed to explain this bone reaction. Animal experiments and clinical studies have shown that bone loss around implants may lead to implant failure, which was associated in many cases with unfavorable loading conditions. Inappropriate loading will cause excessive stress in the bone around the implant and may result in bone resorption.
The main goal of this research is to investigate the effects of stress distribution of the fundamental biomechanics of different implants with vary screw types and screw pitches. Two different types of screw threads was used : triangular -thread and trapezoid -thread. Both threads have screw pitches of 0.8, 1.2, and 1.6mm, totaling five different experimental models. Three-dimensional anatomic models were constructed by finite element method with contour scanning and cross section slicing.
Stress distribution is concentrated at the neck of implant where the first thread of implant contact with cortex bone. When the directions of load are form buccal and lingual side, the compressive stress of alveolar bone and von Mises stress of implant are higher than vertical loading. In triangular screw type implant, stress increases with the screw pitch. And in trapezoid screw type implant, stress increases with the decreasing of screw pitch.
By analyzing the stress distributions, it was induced by different directions of occlusion forces, we can investigate the effects of occlusions, which distribute on the different implant structure and also study the stress which distribute in mandible with different implant structure will be analyzed with osseointegration theory.
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