Effect of Surface Treatments on the Bond Strength to Ceramic

Objectives: The aim of this study was to investigate the effect of two surface treatments, fatigue and thermocycling on the microtensile bond strength of the ceramic IPS e.max Press/resin cement/composite. Methods: Eighteen ceramic (Ivoclar) bars (10mm length x 7mm width x 3.0mm thickness) were made, and divided into 6 groups (n=3): Groups 1, 2, 3 - sandblasting for 5 s with 50µm aluminum oxide particles; Groups 4, 5, 6 – acid etching with 10% hydrofluoric acid for 20 s. Silane was applied on treated ceramic surfaces and the bars were bonded to a block of composite Charisma (Heraeus-Kulzer) with RelyX ARC (3M ESPE) resin cement and light cured for 40 s. Specimens of the groups 1 and 4 were storage in distilled water at 37°C for 24 hours, groups 2 and 5 submitted to 3,000 thermocycles between 5 and 55°C and groups 3 and 6 submitted to a fatigue test for 100,000 cycles with 2 HZ. Specimens were sectioned perpendicular to the bonding area to obtain 1mm² sectional area sticks (20 sticks per groups) and submitted to a microtensile bond strength test at a crosshead speed of 0.5mm/min. The data were statistically analyzed using ANOVA and Tukey's test (p<0.05). Results: The microtensile bond strength values (MPa) for the specimens stored at 24 hours: groups 1 (26.9) and 4 (35.0) were significantly stronger than fatigue groups 2 (22.2) and 5 (24.3) and termocycled groups 3 (21.2) and 6 (23.9). No difference statistically was found between the surface treated with hydrofluoric acid and sandblasting with 50µm aluminum oxide particles. Conclusions: The fatigue and thermocycling provided significantly decrease on the microtensile bond strength for both ceramic surface treatments in relation to control groups. No difference was found between the surface treated with hydrofluoric acid and sandblasting with 50µm aluminum oxide particles.