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Many unsolved problems in dental implant research concern the interfacial stress distributions between the implant components, as well as between the implant surface and contacting bone. To obtain a mechanical understanding of how vertical and horizontal occlusal forces are distributed in this context, it is crucial to develop in vitro testing systems to measure the force transmission between dental implants and attached prostheses. A new approach to such testing, involving a robotic system, is described in this investigation. The system has been designed to produce simulated mandibular movements and occlusal contact forces so that various implant designs and procedures can be thoroughly tested and evaluated before animal testing or human clinical trials. Two commonly used fixed prosthesis designs used to connect an implant and a tooth, a rigid connection and a non rigid connection, were fabricated and used for experimental verification. The displacement and force distributions generated during simulated chewing activities were measured in vitro. Force levels, potentially harmful to human bone surrounding the connected dental implant and tooth, were analyzed. These results are useful in the design of prostheses and connecting components that will reduce failures and limit stress transfer to the implant/bone interface.

Presented in this work is a numerically efficient algorithm for treating the periodic steady-state response of flexible mechanisms as the solution to separated two-point boundary value problems. The finite element method is applied to discretize continuous elastic mechanism systems and a set of second-order ordinary differential equations is obtained with periodically time-varying coefficient matrices and forcing vectors. Modal analysis techniques are employed to decouple these equations into a number of single scalar ordinary differential equations in modal basis. The periodic time- boundary conditions at both ends of a fundamental period equal to a cycle of input motion are mathematically separated by introducing auxiliary variables, thus resulting in a so-called almost-block- diagonal matrix for linear algebraic systems of equations. Solving such a system is computationally less expensive than solving a general linear algebraic system. Examples are included to illustrate the procedures applied to a four-bar linkage through which computing time is compared with other approaches.