Improved adhesion of Y-TZP ceramics: a novel approach for surface modification

The aim of this study was to evaluate the effect of novel surface treatments of Y-TZP ceramics on initial shear bond strengths to resin cement. Eighty-four samples (7 x 6 x 5 mm) were randomly divided into 6 groups (n=14): Group1 (G1), no treatment; Group 2 (G2), air-borne particle abrasion with silica-coated aluminum oxide particles; Group 3 (G3), vitreous application 1 + etching with hydrofluoric acid; Group 4 (G4), vitreous application 1 + tribosilicatization; Group 5 (G5), vitreous application 2 + etching; Group 6 (G6), vitreous application 2 + tribosilicatization. Surface roughness (Ra) evaluation was performed by optical profilometry, scanning electron microscopy, and X-ray spectroscopy. The samples were silanized, and resin cement cylinders (3 x 2 mm) were built on the treated surfaces, light-cured and submitted to shear testing (1 mm/min). The failure mode was evaluated by SEM. Bond strength data were statistically analyzed using 1-way ANOVA and Tukey's test (α=0.05). Bond strength results were significantly affected by surface treatments (P = 0.0001). G5 and G3 presented increased Ra parameters and showed highest bond strength results (17.8 ± 5.5 and 13.3 ± 4.1, respectively). Failure modes were mainly mixed in all groups except for G1. The results confirmed that the approach of coating surface-conditioned Y-TZP with a vitreous material increased the initial shear bond strength to resin cement.