Air Abrasion vs. Tribochemical Silica Coating: Effect on Translucent Zirconia Bond Strength

Objectives: This study evaluated the microshear bond strength between resin cement and three translucent zirconias (3Y-PSZ, 4Y-PSZ, and 5Y-PSZ) following air abrasion with aluminum oxide (Al2O3) or tribochemical silica coating (CoJet), before and after thermal cycling. 3Y-TZP was included as a control. Methods: Zirconia specimens were treated with air abrasion or CoJet, followed by the application of a zirconia primer and adhesive. Dual-cured resin cement cylinders were then bonded to the treated surfaces for microshear bond strength testing after 7 days in distilled water or after aging (30 days and 10,000 thermal cycles). Data were analyzed using three-wayANOVA (zirconia, treatment, and aging) and Tukey's test (alpha = 0.05). Results: The triple interaction was not significant. Treatment*time and zirconia*time interactions were significant (p<0.001). 3Y-TZP exhibited higher bond strength at 7 days. Higher bond strength values were obtained for CoJet and Al2O3 air abrasion groups at 7 days (13.47 +/- 3.55 MPa). All specimens presented adhesive failures. Conclusion: The type of zirconia significantly influenced the microshear bond strength. 3Y-TZP showed greater bond strength compared to translucent zirconias. Tribochemical coating promoted higher bond strength at both time points. Thermal cycling negatively affected the bond strength of all zirconias evaluated. Clinical relevance: The observed variations in bond strength among different translucent zirconias emphasize the importance of material selection for optimal clinical outcomes. Additionally, the positive influence of tribochemical silica coating on bond strength highlights its potential as a valuable surface treatment for enhancing the durability of zirconia-based restorations in the oral environment. However, the detrimental effects of thermal cycling on bond strength emphasize the need for careful clinical considerations when fabricating and cementing translucent zirconia restorations.