Influence of layer thickness on stress distribution in ceramic-cement-dentin multilayer systems.

The effects of dentin and cement thicknesses on stress level and distribution of crack propagation in ceramic-cement-dentin multilayer complex were analyzed. Custom-designed finite element analysis program based on JL Analyzer was used to analyze the stress distribution and present the maximum principal stress locations. In Zirconia, all the maximum stress values were above 100 MPa. In Empress II, they ranged between 50 and 105 MPa, which were approximately one-third of those of Zirconia. In Feldspathic, the maximum stress values were generally lower than 50 MPa. In all groups with 30 microm cement thickness, the highest values were observed at the bottom surface. For cement thicknesses at 50, 70, and 100 microm, maximum stress was found to occur at the top surface. However, changes in dentin thickness did not bring about significant changes in maximum stress values. Results of this study revealed the roles played by the following variables in the failure of a multilayer structure: cement thickness had a minor influence, dentin thickness exerted no influence, but the thickness and type of ceramic system played a significant role.