Effect of low temperature degradation on multi-layered zirconia block for dental CAD/CAM

Ceramic prosthesis fabrication using CAD/CAM has advantages such as high convenience, fast fabrication speed, and high esthetics, resulted in increasing use in clinical practice. Among them, the multi-layered zirconia block for dental CAD/CAM is a product that consists of a single block with layers of different shades, so that natural tooth color can be reproduced. However, research on the material is insufficient, and in particular, the study on the characteristics of low-temperature degradation, which is known to be important for zirconia-based medical devices, is required to evaluate the performance and safety of the material. In this study, in order to evaluate the effect of low-temperature degradation on the properties of multi-layered zirconia blocks, three-point flexural strength, fracture surface and phase changes before and after low-temperature degradation of three companies’ dental CAD/CAM multi-layered zirconia block products were compared. As a result of this experiment, all products of the three manufacturers met International Standards, and there was no change in strength even after low-temperature degradation. However, it was found that there were differences in monoclinic content, three-point flexural strength, and the surface crystal structure for each zirconia block.restrictio