치조골 밀도가 다른 조건 하에서 임플란트 bar attachment와 지지조직의 유한요소 응력 분석

Abstract

The implantation considering the biomechanic analysis on the bone density is required for implant-supported overdenture. The osseointegrated implant under the excessive high stresses cause the implant fixture fracture, superstructure fracture, screw loosening, and pathologic alveolar bone resorption, because the stresses from occlusal loading don't reduce in PDL such as natural tooth, but transfer directly at the surrounding bone. Therefore, the biomechanic analysis on the stress distribution in the bone density and variable loading option must contribute significantly for successful design for overdenture. In our study, the cancellous bone density of alveolar ridge supporting implant fixture was classified into 2 types, and the perfect osseointegration was supposed. The cases of load applying to the implant fixture was set as the vertical and oblique directions, and the portions where load were applied were the center of bar and 4.8mm left from the center. Then the finite element model which was composed of new bar attachment of the implant was prepared, and the finite element analysis of the stress and displacement was calculated. The conclusions were as follows; 1. In comparison with stress and displacement distribution between models with differential cancellous bone density, it tends to be generally similar, and the stress in the cortical bone was increased and the stress in the cancellous bone was decreased in proportion to increased bone density. And the displacement of the cortical bone, the cancellous bone and the all model was increased in proportion to decreased cancellous bone density. 2. As analyzing the stress according to loading direction, more stressful aspect is shown according to oblique direction than to vertical direction. 3. In comparison with asymmetrical loading, the stress tends to be generally distributed to compact bone and cancellous bone during loading on the center of the bar. This shows the same results without any accordance with bone quality. 4. The stress was concentrated on the coronal portion of implant and implant-alveolar interface.