Influence of Different Surface Treatments on the Bond Strength of Yttria-Stabilized Tetragonal Zirconia Ceramic

This in vitro study evaluates the shear bond strength (SBS) of yttria-stabilized tetragonal zirconia (Y-TZP) and resin cement after different surface treatments. Forty-eight ceramic cubes were divided into four groups (n = 12): G1 (control) sandblasting with Al₂O₃; G2-sandblasting with silica-coated Al₂O₃ (Rocatec); G3-Rocatec + CO₂ laser; and G4-CO₂ laser + Rocatec. A metallic primer was applied to the pretreated ceramic. A rubber ring was adapted on the central area, and then, the resin cement was inserted into the matrix and photoactivated. The samples were evaluated regarding surface roughness (Ra), SBS, failure type, and qualitatively with scanning electron microscopy (SEM). The data were analyzed by one-way analysis of variance followed by Tukey's test (p < 0.05). The mean values of Ra (μm) were as follows: G1-4.52^a, G2-4.24^a,b, G3-4.10^a,b, and G4-2.90^b and the mean values of SBS (MPa) were as follows: G1-7.84^a , G2-4.41^b , G3-4.61^b and G4-6.14^a,b. SEM analyses showed superficial irregularities for all groups, being more prominent for G1. The presence of silica deposits was observed for G2, G3, and G4, but in the last two groups there were some linear areas, promoted by the fusion of silica, due to the thermomechanical action of the CO₂ laser. The surface treatment with CO₂ laser + Rocatec, using one MDP-based cement, can be an alternative protocol for the adhesion cementation of Y-TZP ceramic since it was as effective as the conventional pretreatment with aluminum oxide sandblasting.