내측 연결 시스템에서 임플란트 고정체의 경부 형태에 따른 지지골에서의 유한요소 응력분석

Abstract

The external contour of an implant can have significant effects on the load transfer characteristics and may result in different bone failure rates for different implant system. The purpose of this study was to investigate the effects of crest module shape and occlusal load direction on bone failure modes of five commercially available dental implant systems. Five different implant systems with internal connection; ITI (Model 1), Astra (Model 2), Bicon (Model 3), Friadent (Model 4), and Paragon (Model 5), comparable in size, but different in thread profile and cest module shapes, were compared using the finite element method. The crown for mandibular first molar was made using cemented abutment. Each three-dimensional finite element model was created with the physical properties of the implant and surrounding bone. This study simulated load of 200N at the centric fossa in a vertical direction (loading condition A), 200N at the centric cusp tip in a 15˚ inward inclined direction (loading condition B), or 200N at the centric cusp tip in a 30˚ outward inclined direction (loading condition C) respectively. Von Mises stresses were recorded and compared in the supporting bone. The following results have been made based on this study: 1. Without regard to the loading condition, the stress distribution pattern of the abutment-implant fixture usually was widely distributed along the inner surface of the implant fixture contacting the abutment post in the internal connection systems. 2. Without regard to the loading condition, the greater stress occured near the superior region of cortical bone around the neck of the implant fixture compared to the travecular bone. 3. The stress in compact bone in case of the inclined loading condition B and C usually was greater than that of the vertical loading condition A. Specially the greatest stress showed in the inclined loading condition C to outside point from the centric cusp tip. 4. The magnitude of the stress occurred at the crestal region around the fixture was greater in the order of the case of Astra, ITI, Paragon, Friadent, Bicon under the vertical loading condition A. 5. The magnitude of the stress occurred at the crestal region around the fixture was greater in the order of the case of Astra, ITI, Bicon, Paragon, Friadent under the inclined loading condition B and C . 6. Without regard to the loading condition, the magnitude of the stress occurred at the crestal region around the fixture was greater in the order of the case of Astra, ITI, Bicon in the friction-fit joint. 7. Without regard to the loading condition, the magnitude of the stress occurred at the crestal region around the fixture was greater in the order of the case of Paragon, Friadent in the slip-fit joint. 8. Converging design of crest module of fixture have much lower stresses compared to diverging or parallel design in the cortical bone around the implant. Conclusively, in the internal connection system of the implant-abutment connection methods, the stress-induced pattern at the supporting bone according to the abutment connection form had differenence among them, and implants with narrowing crestal module cross-sections at the top of the cortical bone created more favorable load transfer characteristics in this region. But it is considered that the future study is necessary about how this difference in the magnitude of the stress have an effect on the practical clinic.