Analysis by finite elements of stresses in the zirconia-porcelain veneer interface

Purpose; The aim of this study was to evaluate stress distributions in the area of the zirconia-porcelain veneer interface, in different tests of adhesive bond strength by the finite element method. Method: Samples (20x4x2 mm) of IPS e.max Ceram porcelain (Ivoclar, n = 3) and Lava Frame® zirconia (3M, n = 3) were prepared to determine the elastic modulus in the Sonelastic® apparatus from the frequencies natural vibration by impulse excitation. These values were used as input data of the properties of the materials evaluated for the simulations. Four three-dimensional models  (zirconia / porcelain veneer) were generated in the ANSYS 19.1 software based on different tests of adhesive bond strength in the literature. These models were evaluated numerically by applying a load of 150 N in the porcelain veneer near the region of the interface, in the different models and the voltage distributions in the interfaces were descriptively analyzed. Result: The measures of the average elastic modulus of IPS e.max Ceram and Lava Frame® were 66.26 and 206.0 GPa, respectively. Models in which zirconia and porcelain had the same cross sections had a higher concentration of adhesive bond strength in the interface region, while in models with different sections, the highest tensions were concentrated in porcelain veneer. Conclusion: When proposing adhesive bond strength assemblies in bilayer samples, samples whose materials have the same cross sections should be used, because the results of the finite element simulations showed a better distribution of stresses in the interface, which would provide more values reliable of the real union of bilayer restorative materials.