Structural analysis of an osseointegrated dental implant system

A dental implant restoration is analyzed as a structure to determine how loads are distributed to the implants. The first part of the work examines the flexibility of the structural components. Measurements are made of the stiffness of an implant embedded in simulated interfacial bone in tension, compression, bending, shear and torsion. The stiffnesses of the mandible and prosthesis are estimated analytically. Comparisons show that only the mandible can be considered rigid in any structural analysis. The implants, interfacial bone and prosthesis must be treated as flexible components in the structure.; With this information, a new structural model is formulated. The prosthesis is represented as a flexible beam with a constant cross-section. The implants are tightly connected to the prosthesis, and the implants and interfacial bone are modelled as elastic materials. The mandible provides a rigid base. Strain energy theory and equations of equilibrium are used to derive a set of equations which can be solved to yield the forces, moments and torques on each implant.; When measured stiffnesses of the implants and interfacial bone are incorporated, the model predicts that, for cantilever loading, the largest compressive forces and moments are generally concentrated on the implant closest to the applied load. It is also found that increasing the cantilever length generally increases the forces and has an even greater effect on the moments. Other clinical factors affecting the force and moment distributions are investigated: the number of implants, implant spacing, implant alignment, prosthesis fit and the degree of implant/interfacial bone stiffness. Predictions from the model are compared to results from in vitro laboratory models and from finite element studies. The comparisons show good agreement for the force distributions. With limited data for comparisons of the moments, there is at least qualitative agreement. Further comparisons to in vivo studies also show qualitative agreement. Hence the new model can be used with a certain degree of confidence to estimate forces, moments and torques in dental implant systems.