Effect of veneering material and technique on the fracture resistance of porcelain-veneered zirconia crowns

Abstract

Context: Different porcelain veneering materials and techniques are used for the fabrication of porcelain-veneered zirconia crowns. Aim: The aim of this study was to examine the effects of different veneering materials and techniques (layering or over pressing) on the fracture resistance of zirconia-based crowns. Materials and Methods: A prepared molar tooth was scanned using computer-aided design/computer-aided manufacturing technology to create a master metal die. The scanned dies was used to produce forty zirconia copings. The zirconia copings were divided into four groups (n = 10) based on the veneering technique used, as follows: over pressing using Cercon Ceram press (PR1), IPS e.max ZirPress (PR2), layering using IPS e.max Ceram (LR1), and VITAVM9 (LR2). All crowns were cemented using glass-ionomer cement and thermocycled for 3000 cycles, between 5°C and 55°C. They were then loaded using a universal testing machine (3.7-mm ball and 0.5-mm/min crosshead speed) until failure. One-way ANOVA with Bonferroni corrections for multiple comparisons was used for the statistical analyses. Results: The means and standard deviations for failure loads were 1420 ± 54 N, 1797 ± 31 N, 1698 ± 36 N, and 2120 ± 73 N for the PR1, PR2, LR1, and LR2 groups, respectively. The differences in failure loads were statistically significant (P Conclusion: The fracture resistance of zirconia-based crowns was affected by the veneering materials and techniques used.