A methodology for fracture strength evaluation of complete denture

ObjectiveThis paper presents a methodology for evaluating the mechanical strength and structural integrity of complete denture based on a thorough study on the mechanical properties of dental material and numerical FEM analysis.MethodsA light curing composite resin, Eclipse (Dentsply International Inc.,– DeguDent GmbH, Hanau, Germany) was tested to evaluate the mechanical properties. According to standards recommendations were performed tensile and bending tests, fracture mechanics and fatigue crack growth rate tests. Using ABAQUS software, was performed a complex FEM analysis on a denture model obtained by 3D scanning and reverse engineering techniques, which may reveal if the applied load can initiate a crack or not. For if a crack is initiated, based on the methodology presented in this study, is analyzed the effect it has on complete denture.ResultsFor a pressure load of 1.5 MPa, applied on palatal cusps of the upper teeth, we identified the stress concentrations areas, the values of maximum principal stress and strain, and were observed that a crack is initiated. Based on XFEM analysis were evaluated the stress intensity factors at the crack tip and was determined an equivalent stress intensity factor, KIeq=7.42 MPa √mm. The value of KIeq is lower than the threshold stress intensity factor range, ΔKth (resulted from experimental tests), which means that the crack initiated is a stationary crack. Based on results, was calculated a risk factor, which give the fracture probability of the complete denture.