Evaluation by finite element analysis of stresses in different cross sections of overdenture-retaining bar with vertical misfit

Abstract

In implant prostheses, the term passive fit is a keyword to the long-term success of the rehabilitations. However, the achievement of passive fit is not always obtained, due to problems linked with the own manufacturing of the prostheses/frameworks. When passive fit does not exist, the ill-fitting framework, during the installation, receive the torque propagates stresses which are distributed to all the osseointegration system. This study proposes to evaluate the stresses in overdentures with bar-clip system, varying the factors: vertical misfit (10, 50, 100 µm); bar materials (Au type IV, Ag-Pd, Ti commercially pure and Co-Cr); and different cross sections of the bar (cylindrical, Hader and drop shape) through the finite element methodology. The tridimensional study models will be made using a 3-D modeling software (SolidWorks 2010, USA) and exported to specific software for analysis (ANSYS Workbench 12, USA). A displacement will be applied to simulate the screw torque. All the analysis will be made in terms of Maximum Principal Stress and von Mises stress, in MPa. Results will be presented in a qualitative way through the figures with the stress distribution in different color gradients, and quantitatively by numerical reading in software of the stresses in certain regions of the models.