Comparative fracture strength analysis of Lava and Digident CAD/CAM zirconia ceramic crowns

PURPOSE: All-ceramic crowns are subject to fracture during function. To minimize this common clinical complication, zirconium oxide has been used as the framework for all-ceramic crowns. The aim of this study was to compare the fracture strengths of two computer-aided design/computer-aided manufacturing (CAD/CAM) zirconia crown systems: Lava and Digident. MATERIALS AND METHODS: Twenty Lava CAD/CAM zirconia crowns and twenty Digident CAD/CAM zirconia crowns were fabricated. A metal die was also duplicated from the original prepared tooth for fracture testing. A universal testing machine was used to determine the fracture strength of the crowns. RESULTS: The mean fracture strengths were as follows: 54.9 ± 15.6 N for the Lava CAD/CAM zirconia crowns and 87.0 ± 16.0 N for the Digident CAD/CAM zirconia crowns. The difference between the mean fracture strengths of the Lava and Digident crowns was statistically significant (P<.001). Lava CAD/CAM zirconia crowns showed a complete fracture of both the veneering porcelain and the core whereas the Digident CAD/CAM zirconia crowns showed fracture only of the veneering porcelain. CONCLUSION: The fracture strengths of CAD/CAM zirconia crowns differ depending on the compatibility of the core material and the veneering porcelain.