Influence of Surface Treatments on the Bond Strength of Resin Cements to Monolithic Zirconia

Purpose: To assess the influence of surface treatment on the microtensile bond strength (μTBS) of resin cements to monolithic zirconia materials. Materials and Methods: Two types of monolithic zirconia (Zenostar T [ZT] and Prettau Anterior [PA]) were evaluated. The specimens were assigned to three groups based on the surface treatment applied: group 1: control, assintered; group 2: sandblasted with 50-μm Al₂O₃; group 3: tribochemically silica sandblasted. Two types of resin cements (Multilink Speed [MS] and Multilink N [MN]) were applied to each group for evaluating the bond strength using the μTBS test. The fractured specimens were observed with a stereomicroscope and SEM. Surface roughness and topography of monolithic zirconia were examined after treatment. Data were analyzed using ANOVA and Tukey's test. A Weibull analysis was performed on the bond strength data. Results: The bond strength was significantly affected by the surface treatment and the type of resin cement (p 0.001), but not by the type of monolithic zirconia (p = 0.387). Surface treatment with tribochemical silica sandblasting revealed significantly higher bond strength (p 0.05) compared with sandblasting with 50-μm Al₂O₃ and control groups. SEM and surface roughness evaluations revealed that the surface morphology and topography of monolithic zirconia was changed due to surface treatments. Conclusion: The surface treatment of monolithic zirconia with tribochemical silica sandblasting enhanced the bond strength between zirconia and resin cements. Resins cements containing adhesive phosphate monomer (APM, MS) provided higher bond strength to monolithic zirconia than non-APM (MN). Keywords: bond strength, microtensile, monolithic zirconia, resin cement, surface roughness, surface treatments