Effect of surface treatment on the shear bond strength of a resin-based cement to porcelain.

The purpose of this in vitro study was to evaluate the effect of different surface treatments on the shear bond strength of a resin-based cement to porcelain. Sixty pairs of 50% aluminous porcelain discs were fabricated. In each pair, one disc measured 6 mm in diameter X 3 mm thickness (A) and the other measured 3 mm in diameter X 3mm thickness (B). The specimens were randomly assigned to 6 groups (n=10 pairs of discs), according to the surface treatment: etching with 10% hydrofluoric acid for 2 or 4 min (G1 and G2); 50-microm particle aluminum oxide sandblasting for 5 s (G3); sandblasting followed by etching for 2 or 4 min (G4 and G5) and control--no treatment (G6). A silane agent was applied to the treated surface of both discs of each pair. Bistite II DC dual-cure resin cement was applied and the B discs were bonded to their respective A discs. Specimens were stored in distilled water at 37 degrees C for 24 h and were tested in shear strength at a crosshead speed of 2 mm/min. Means in MPa were: G1: 14.21 +/- 4.68; G2: 8.92 +/- 3.02; G3: 10.04 +/- 2.37; G4: 12.74 +/- 5.15; G5: 10.99 +/- 3.35; G6: 6.09 +/- 1.84. Data were compared by one-way ANOVA and Tukey's test at 5% significance level. Bond strength recorded after 2-min acid etching was significantly higher than 4-min etching (p<0.05) and control (p<0.05), but did not differ significantly from sandblasting alone (p>0.05) or followed by etching for 2 or 4 min (p>0.05). Within the limitations of an in vitro study, it may be concluded that 2-min hydrofluoric acid etching produced a favorable micromechanical retention that enhanced resin cement bond strength to porcelain.