Micromechanical analysis of bone at a bone-implant interface

When an implant system is loaded by uncontrolled force, marginal bone loss around implant occurs and eventually leads the entire system to failure. As one of the most important factors related to the failure of implant system, many researchers have indicated the poor bone quality around implant. Nevertheless, to date, few experiments have been performed to determine the properties of interfacial bone around implant. Due to the limited area of bone-implant interface, it has been hard to apply conventional mechanical testing methods to measure the properties of the interfacial bone around an implant. The present study explored recently developed testing systems to assess micromechanical properties of bone at the bone-implant interface. Then, based on the values obtained from the new methods, a possible mechanism was examined for the bone loss around the implant under loading. The bone properties measured by nanoindentation tests showed the modulus of the healed interfacial bone decreased at the region closer to the implant. Mori-Tanaka model for bone based on the values from nanoindentation approximated the overall properties of bone and showed good agree with the experimental values measured by traditional mechanical tests. Displacement machine vision photogrammetry (DISMAP) visualized microstrains could vary at the microstructural level. The magnitudes of microstrains at the microstructural level of bone in tension revealed 4 to 14 times higher values than the overall strain values computed via a nominal average strain approach. As an application based on the data collected from the previous parts of this thesis, a more comprehensive FE model was successfully developed for the bone-implant interface. The present micromechanical analysis of the interfacial bone will contribute to future studies of events at loaded bone-implant interfaces.