| Summary: | 碩士 === 台北醫學院 === 口腔復健醫學研究所 === 88 === Although there were numerous studies published on the stability of dental implant during osseointegration, but up to now there is still a strong demand for a simple device to be used to evaluate the boundary conditions during bone healing. Natural frequency is a function of the mass and stiffness of a material. Such concept has been used to detect changes in boundary conditions of a structure. Thus current study was based on the methodology of modal testing, from both in vitro and in vivo, analyze the processes of osseointegration and variation in boundary condition. From our in vitro study, it was found that natural frequency of test implant increased with stiffness of boundary material. With different implant bed conditions, the slope of the healing curve would show corresponding changes. On the other hand, natural frequency and removal torque value reached the plateau at the same time. However, before the plateau phase, method only natural frequency will be able to detect changes in boundary conditions, but not with removal torque method. Although we found linear correlation between natural frequency and removal torque values, but the correlation coefficient was only 25.3 %. In the in vivo condition, along with the process of osseointegration the increase in natural frequency of a implant was about 227 Hz ~ 334 Hz per week. The final healing time was affected by individual differences, and operation conditions. Also, when the surgery was not successful, natural frequency showed 12% reduction during the first week of healing. In the in vitro experiment, our results showed a positive correlation between natural frequency and boundary heights, boundary width, and boundary density. It was found that as boundary density decreased, boundary width increased, natural frequency method would show highest sensitivity in detection of changes in boundary height. Also, along with changes in boundary density, the natural frequency would show significant changes (p<0.05). Thus, it is concluded that natural frequency is an effective method to detect variation in boundary condition during osseointegration of an implant.
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