Finite element analysis of stress in bone adjacent to dental implants.

Understanding how clinical variables affect stress distribution facilitates optimal prosthesis design and fabrication and may lead to a decrease in mechanical failures as well as improve implant longevity. In this study, the many clinical variations present in an implant-supported prosthesis were analyzed by a 3-dimensional finite-element method. The anterior segment of a human mandible treated with 5 implants supporting a curved beam was created to perform the tests. The variables introduced in the computer model were cantilever length, elastic modulus of cancellous bone, abutment length, implant length, and framework alloy (AgPd or CoCr). The computer was programmed with physical properties of the materials as derived from the literature, and a 100-N vertical load was used to simulate the occlusal force. Images with fringes of stress were obtained, and the maximum stress at each site was plotted in graphs for comparison. Stresses tended to be concentrated at the cortical bone around the neck of the implant closest to the load, whereas stresses in cancellous bone were considered low. In general, the stress distribution was better with stiffer cancellous bone, longer abutments and implants, and shorter cantilevers. The use of a CoCr alloy framework appears to contribute to a better stress distribution.