Pilot Evaluation of Four Experimental Conditioning Treatments to Improve the Bond Strength between Resin Cement and Y-TZP Ceramic

Purpose: This study evaluated the bond strength between resin cement and Y-TZP ceramic (Yttrium-stabilized Tetragonal Zirconia Polycrystalline) submitted to different surface conditionings. Materials and Methods: Fifty Y-TZP ceramic discs (empty set = 10 mm) were allocated into five groups: Gr1 (control)-no conditioning; Gr2-tribochemical silica coating (30-mu mSiO(2)) before sintering; Gr3-air abrasion with 50-mu m Al(2)O(3) before sintering; Gr4-air abrasion with 110-mu Al(2)O(3) before sintering; Gr5 - air abrasion with 50-mu m Al(2)O(3) after sintering. After specimen preparation, cylinders of composite resin were prepared and immediately cemented onto the ceramic. A shear test was performed. Results: One-way ANOVA indicated a statistically significant difference among the groups (p = 0.0019). The mean shear bond strengths (MPa) were: Gr1 = 4.7 +/- 0.8,(b) Gr2 = 4.6 +/- 0.9,(b) Gr3 = 6.4 +/- 1.0,(a) Gr4 = 6.5 +/- 1.8,(a) Gr5 = 6 +/- 1.3(ab) (same superscript letter indicates statistical similarity). Adhesive fracture between the ceramic and resin cement was the most common failure. No complete cohesive fracture at the ceramic or composite cylinders was noted. Conclusion: Within the limitations of this study, additional surface treatment with air abrasion before and after sintering provided a significant increase in bond strength. Tribochemical silica coating before sintering was not effective as a surface treatment.