Strength and Fracture Mode for Dental Colored ZrO<sub>2</sub> Ceramics Coated with Dental Porcelain

The purpose of this study was to investigate the flexural strength and the mode of failure of dental colored ZrO2 ceramics with or without porcelain coating. Colorants (Fe2O3,CeO2, etc.) were mixed with 3Y-TZP powder to prepare colored dental zirconia. Specimens were made in monolithic or bilayered forms which were coated with veneering porcelain. Experimental results showed that there were not significantly differences of bending strengths between white and colored materials or between bilayered specimen, while the strength of monolithic specimen were significantly higher than their bilayered counterpart. In all bilayered specimens, the bulk fracture initiated at the tensile surface of the core material and was consistently accompanied with porcelain crush and delamination at the interface. Colorants for 3Y-TZP had minor effects on its mechanical properties.