Evaluation of surface properties and shear bond strength of zirconia substructure after sandblasting and acid etching

Abstract

Abstract To compare the effects of different surface treatment methods on the surface characteristics of yttria-stabilized tetragonal zirconia (Y-TZP) and relevant shear bond strength (SBS) between zirconia and composite resin. Forty-eight Y-TZP ceramics were randomly divided into four groups based on the specific surface treatments: Group C (blank treatment), Group Sand (sandblasting with 80 μm Al2O3 particles), Group HF (etched with 40% hydrofluoric acid for 10 min), and Group H2SO4 (etched with hot sulfuric acid for 10 min). Surface characteristics of the treated specimens, including morphology, roughness, wettability, chemical composition and crystalline structure were analyzed. SBS was tested by bonding ceramics to resin cement in the same group. Kruskal-Wallis test followed by pair wise comparison was conducted for statistical processing. A significance level of α = 0.05 was set. Three kinds of surface structures with different widths and heights in roughness were obtained, including micron-scale pit/peak size by sandblasting, nano-scale pit/peak size by hydrofluoric acid etching and middle submicron-scale pit/peak size by hot sulfuric acid etching. By comparison, the specimens of Group HF showed the most favorable wettability, the highest SBS and the lowest phase transformation than those of other groups. Therefore, HF etching was considered as a promising surface treatment to promote resin–zirconia bonding without excessive surface damage. The height, width, frequency and regularity of roughness altogether affected the shear strength.