| Summary: | 碩士 === 國立臺北科技大學 === 機械工程系機電整合碩士班 === 107 === At present, most of the dental implants used in clinical treatment lack buffer design and cannot provide the escape mechanism possessed by natural teeth. When biting hard objects during chewing, the force will be directly and quickly transmitted to the root of the implant, which will raise the risk of breakage of the bone around the implant.
The purpose of this study was to develop a fluid-solid coupled buffering mechanism, which could be applied to a novel movable artificial dental implant. Then, the influence of biomechanics was evaluated by finite element analysis. It was expected that the implant with unique buffer mechanism can simulate the property of natural teeth.
In this study, fluid-solid coupled buffering mechanism was expected to have the similar mechanical property of the periodontal ligament. Silicon rubber was chosen as the solid phase and water was chosen as the liquid phase of the buffering mechanism. To improve computation efficiency, all finite element models were simplified and divided into two parts: (1) When under occlusion load and horizontal impact load, the effects of different elastic moduli of silicone rubber materials (RTV #312, RTV #533 and RTV #7099) on the bone stresses around the implant were evaluated. Then, the results would be compared with that of a traditional implant. (2) The material properties of the silicon rubbers were obtained by compression tests. Also, the theoretical and experimental values ere compared and validated. Then, the effects of different hole designs (slope of holes: A, B; total number of holes: 4, 8 10, 12) of the fluid-solid coupled buffering mechanism were investigated.
According to the comparison results with the traditional implant, the implant with silicone rubber as the solid matrix in the fluid-solid coupled buffering mechanism could effectively reduce the bone stress around the implant by more than 15.1%. However, when observing the the load-displacement curve under occlusion load, it showed that both RTV #533 and RTV #7099 had better buffering and rebounding capabilities than RTV #312.
From the results of horizontal impact, it could predict that the novel movable artificial dental implant developed in this study would be broken before the bone stress around the implant reached its ultimate strength. In other word, it could reduce the hazard of bone fracture around the implant effectively when a sudden horizontal impact load was applied on the implant.
According to the results of solid-fluid coupled analysis, no significant difference was found for the load-displacement results when changing the slopes of holes during occlusion load. When the number of holes were changed from 4 to 8, there was still no significant difference. However, when the number of holes was increased to 10 and 12, it was found that the sinking velocity of the upper abutment begins to decrease. Moreover, as the number of holes was increased, the sinking velocity became slower. The size of the flow channel in this study was too large so that it could not effectively limit the rising speed of upper abutment. During the unloading process, the rising velocity of all groups is very high and the upper abutment would be encountered several fluctuations to become stable.
Based on the results of this study, the novel movable artificial dental implant with fluid-solid coupled buffering mechanism can effectively reduce the bone stress around the implant. On the other hand, by changing the mechanical properties of the solid phase and controlling the liquid phase with different hole shapes, it will affect the sinking and rising velocities. In the future, it is necessary to change the above two parameters to more accurately mimic the “escape mechanism” of the periodontal ligament.
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