Evaluation by finite element analysis of stress at different cross-sections design of overdenture's bar framework with vertical misfit

The objective of this study was to evaluate by 3-D finite element analysis tensions occurred in overdentures with bar-clip retention systems, when different cross-sectional geometries (circular, oval or Hader) have different levels of vertical misfit (50, 100 and 200 µm) and were maded from different metallic alloys (type IV Au , Ag-Pd , Co-Cr and Ti cp). Three-dimensional models were maded using 3-D modeling software (SolidWorks 2010) and imported into the software of mechanical simulation (ANSYS Workbench 11). A displacement simulating screw tightening was done until proper fitting of the prosthetic platform infrastructure. The analyzes were performed in order to obtain the Maximum Principal Stress and von Mises (MPa). The stress values increased proportionally with the level of vertical misfit and Hader bar showed the highest values. Circular bars made with Au type IV showed the lowest values on the bar and prosthetic screw. Resilient alloys performed better than hard, while the greater complexity of the cross section of the bar and the highest levels of vertical misfit increased stress concentration on the infrastructure of the bar, prosthetic screw and cortical bone tissue. The stress induced on the bar, prosthetic screw and peri-implant bone tissue were influenced by increased vertical misfit, complexity of cross section and different alloys of the bar (AU)