Background: Despite their favorable aesthetics and biocompatibility, ceramic restorations with zirconia frameworks often suffer from weak bonding between the zirconia core and the porcelain veneer, leading to failure and chipping. This study aimed to investigate the effect of acid etching duration on the shear bond strength between these two materials.
Methods: In this experimental in vitro study, 60 zirconia block specimens with defined standards were prepared. The specimens were divided into four groups: a control group (no etching) and three treatment groups subjected to Zircos-E etching solution for half, one, and two hours. After etching, porcelain veneers were fired onto the specimens. Shear bond strength was measured using a universal testing machine at a crosshead speed of 1 mm/min. Data were analyzed using Kolmogorov-Smirnov, t-test, one-way and two-way ANOVA, and Bonferroni post-hoc tests in SPSS version 19 (P < 0.05).
Results: Shear bond strength was significantly higher in all three acid-etched groups compared to the control group (P < 0.001). However, no significant differences were observed among the three etched groups (P = 0.999).
Conclusion: Acid etching of zirconia significantly improves bond strength compared to no surface treatment. However, increasing the etching time from half an hour to two hours does not result in any further significant improvement. The application of this technique may help reduce the failure rate of fixed prosthodontic treatments.