The Influence of Internal Surface Treatments on Tensile Bond Strength for Two Ceramic Systems.

Statement of the Problem: The ceramic composition and surface microstructure of all-ceramic restorations are important components of an effective bonding substrate. Hydrofluoric acid and sandblasting are well-known procedures for surface treatment; however, surface treatment for high alumina-containing and lithium disilicate ceramics have not been fully investigated. Purpose: This in vitro study evaluated the tensile bond strength of resin cement to two types of ceramic systems with different surface treatments. Methods and Materials: Thirty specimens of each ceramic system were made according to the manufacturer's instructions and embedded in polyester resin. Specimens of In-Ceram Alumina [I] and IPS Empress 2 [E] were distributed to three groups with differing surface treatments (n=10): sandblasting with 50 µm aluminum oxide (APA); sandblasting with 110 µm aluminum oxide modified with silica particles (ROCATEC System-RS); a combination of sandblasting with APA and 10% hydrofluoric acid etching (HA) for two minutes on In-Ceram and for 20 seconds for IPS Empress 2. After the respective surface treatments, all the specimens were silanated, and Rely-X resin cement was injected onto the ceramic surface and light polymerized. The specimens were stored hi distilled water at 37°C for 24 hours and thermally cycled 1,100 times (5°C/55°C). The tensile bond strength test was performed in a universal testing machine at a 0.5 mm/minute crosshead speed. Results: The mean bond strength values (MPa) for IPS Empress 2 were 12.01 ± 5.93 (EAPA), 10.34 ± 1.77 (ERS) and 14.49 ± 3.04 (EHA). The mean bond strength values for In-Ceram Alumina were 9.87 ± 2.40 (IAPA) and 20.40 ± 6.27 (IRS). All In-Ceram specimens treated with 10% hydrofluoric acid failed during thermal cycling. Conclusion: The Rocatec system was the most effective surface treatment for In-Ceram Alumina ceramics; whereas, the combination of aluminum oxide sandblasting and hydrofluoric acid etching for 20 seconds worked more effectively for Empress 2 ceramics. [ABSTRACT FROM AUTHOR]