| Summary: | 碩士 === 義守大學 === 生物醫學工程學系碩士班 === 98 === Osseointegration is one of an important index to evaluate the success rates of dental implantation. The insufficiency of the osseointegration and increase of micromotion can enhance the failure risk of the implant at the early healing stage. The purpose of this study was to investigate the influence of stress distribution and micromotion of the implant with different percentages and patterns of the osseointegration by three-dimensional finite element analysis.
The finite element models of this study were constructed by two procedures including computer-aided engineering design and dental computerized tomography reconstruction. The three-dimensional finite element models were consisted of a porcelain crown, the implant, an osseointegration unit and a portion of the mandibular corpus. The osseointegration layer between implant surface and surrounding bone were arranged as the osseointegration units of one layer and five layers corresponding with cortical and cancellous bone. Each layer of osseointegration units, the thickness of a layer is 2 mm, were further divided into four parts calling sub-osseointegration unit. Therefore, 24 parts of the sub-osseointegration units for the finite element model were generated to simulate the oeesointegrated effects of peri-implant bone. Three percentages and five distributed patterns in the cortical osseointegration combined with four percentages and six distributed patterns in the cancellous osseointegration were assumed by according to the osseointegration conditions and investigated the differences of the stress distributions and micromotions. The bounding condition of lateral sides of the mandible was fixed. The loading conditions, the forces of axial, oblique, and central axial direction were 114.6, 100 and 250 Newton, were applied at the linguodistal cusp , linguomesial cusp and central fossa of first molar. The results of the maximum Von Mises stress and micromotion of finite element analysis reveal that the peak value in Von Mises stress were detected mainly concentrating at the regions of neck and apex of the implant. A better four-neighbors connectivity of osseointegration unit within cortical and concellous bone revealed a tendency that the maximum Von Mises stresses in the alveolar bone and implant were decreased significantly when the percentages of osseointegration was low. In addition, increase osseointegration percentages and patterns where located at the buccal side could provide an evidence of stress reduction. The results of the osseointegration percentages and patterns of the finite element analysis showed that the least stresses on the osseointegration units were occurred in the osseointegration percentages of 20% of concellous layer combining with second osseointegration patterns. The micromotions of alveolar bone near implant neck from all finite element models were detected lesser than 100μm. Although, the most notable region of whole finite element model for the micromotion change was observed in the lingual side, the osseointegration percentages of 60% revealed the smallest micromotion in this study and showed to have a better stability of the implantation.
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