Effect of different air-abrasion protocols on topography, surface wettability and adhesion of MDP monomer-based resin cement to zirconia

This study evaluated the effect of air-abrasion protocols on the topography, surface wettability and adhesion of resin cement to zirconia. Ceramic specimens (N = 49; n = 7) (15 mm × 2 mm) were randomly allocated to seven groups to be treated with: (1) Air-abrasion with 45 μm Al2O3 (A45), (2) 80 μm Al2O3 (A80), (3) 30 μm Al2O3 coated with SiO2 (CoJet) (C30), (4) 30 μm Al2O3 coated with SiO2 (Rocatec Soft) (R30), (5) 110 μm Al2O3 coated with SiO2 (Rocatec Plus) (R110); (6) R110R30 (Rocatec) (R110R30) and (7) control, no conditioning (NC). Air-abrasion was performed using a chairside air-abrasion device (2.5 bar, 10 mm, 90 s). Contact angle measurements were performed using goniometry (n = 5). MDP-based dual resin cement (Panavia F2.0) was bonded on four locations after air-abrasion protocols (n = 20 per group). Half of the specimens were tested after 24 h and the other half after thermal cycling (×3000, 5–55 °C). Data were analyzed using 1-, 2-way ANOVA and Tukey’s test (alpha = 0.05). Significantly lower contact angle values were observed for groups C30 (62.6 ± 0.91), R30 (61.91 ± 1.05) and R110R30 (61.54 ± 1.02) compared to those of other groups (65.5 ± 0.9–110.61 ± 0.9) (p < 0.05). In dry conditions, surface conditioning methods tested did not show significant effect on bond strength (MPa) (10.57 ± 1.42–16.86 ± 2.54) (p = 0.238). After thermocycling, bond strength results decreased significantly (p < 0.05) (12.6–51.2%). R110 (7.18 ± 1.34) and A80 (4.92 ± 1.53) showed significantly higher bond strength compared to other groups (2.13 ± 0.73–4.16 ± 1.34) (p < 0.05). The best wettability and adhesion results with MDP-based resin cement to zirconia was achieved with A80 and R110 air-abrasion.