Influence of Silane on Resin Cement Bond Strength to Zirconia

Application of a silane coupling agent to the surface of sintered alumina based ceramics can improve the bond strength of a resin luting agent to the ceramic material. It is well established that silane coupling agents form oxane bonds to mineral surfaces like Al and Zr but it is not obvious whether these bonds are stable since they are susceptible to hydrolysis. Objective: To determine the bond strengths of a resin luting agent to zirconia ceramic surfaces treated with and without a silane coupling agent. Method: Four mm thick zirconia plates (ZirCAD, Ivoclar) were sectioned from blocks, heat treated and embedded in acrylic resin. The zirconia surface was air abraded with 50 µm aluminum oxide (50 lbs/in²) from a 10 mm distance, then ultrasonically cleaned and dried. Light-polymerized composite cylinders (3.9 mm diameter, N= 46) were formed in glass molds with the surfaces made flat, roughened then cleaned with 37.5% phosphoric acid, rinsed and dried prior to silane application for 1 min followed by air drying to enhance the cement bond. Cylinders were then cemented using a dual-polymerized resin cement (RelyX Unicem Aplicap, 3M ESPE) to zirconia surfaces, either clean (NS) or pretreated with a silane coupling agent (S). A 4 kg load was applied to the cylinders during cementation and light applied to initiate light polymerization for 30 seconds. All cemented plates were stored dry for 24 hrs and then tested in shear mode (crosshead speed 1.0 mm/min). Only specimens that failed adhesively between the ceramic and cement surfaces were statistically analyzed. Results: One-way ANOVA(α=0.05) revealed no statistically significant difference in shear bond strength (MPa) between groups S (11.56 ±4.90) and NS (10.48 ±4.24). Conclusion: Silane did not improve the shear bond strength between the zirconia ceramic and resin luting agent.