Purpose: This study evaluated the effects of different bar materials on stress distribution in an overdenture-retaining bar system with a vertical misfit between implant and bar framework.
Materials and methods: A three-dimentional finite element model was created including two titanium implants and a bar framework placed in the anterior part of a severely reabsorbed jaw. The model set was exported to mechanical simulation software, where displacement was applied to simulate the screw torque limited by 100-microm vertical misfit. Four bar materials (gold alloy, silver-palladium alloy, commercially pure titanium, cobalt-chromium alloy) were simulated in the analysis. Data were qualitatively evaluated using Von Mises stress given by the software.
Results: The models showed stress concentration in cortical bone corresponding to the cervical part of the implant, and in cancellous bone corresponding to the apical part of the implant; however, in these regions few changes were observed in the levels of stress on the different bar materials analyzed. In the bar framework, screw, and implant, considerable increase in stress was observed when the elastic modulus of the bar material was increased.
Conclusions: The different materials of the overdenture-retaining bar did not present considerable influence on the stress levels in the periimplant bone tissue, while the mechanical components of the system were more sensitive to the material stiffness.