Effect of different coating methods on resin bond strength to zirconia

A clinical challenge of using zirconia frameworks is to achieve adequate bond with different substrates. This study aimed to evaluate the effect of bioglass and silica coating of zirconia substrates on microshear bond strength of resin cement to tetragonal zirconia. This laboratory experimental study was conducted on zirconia discs. A total of 120 YTZP zirconia (Zirkonzahn) discs were fabricated and based on surface treatments were categorized into 8 groups of 15 including 1. Control, 2.Sandblast, 3. Etch + bioglass powder coating, 4. Silane + etch + bioglass powder coating, 5. Etch + bioglass slurry coating, 6. Silane + etch+ bioglass slurry coating. 7. Silane + colloidal silica coating, and 8. Silane + etch + colloidal silica coating. Samples were subjected to microshear bond strength testing. In coated groups, thickness of the coating was measured as well. Kruskal Wallis test and ANOVA were applied for intragroup statistical analysis and Dunnett’s test and Mann Whitney U test were used for pairwise comparisons. The mean bond strength of silica-coated samples was significantly lower than the sandblasted specimens (P<0.001). No significant difference was detected in the mean bond strength between specimens with different glass coatings and sandblasted samples. In other words, bond strength of sandblasted and different glass-coated samples was not significantly different. The thickness of coating in the slurry group was significantly less than in other groups. Bioglass coating could effectively increase the bond strength of resin cement to zirconia in short-term.