Effect of glass–ceramic coating versus alumina air-abrasion on the bond strength and residual stress of zirconia.

Objectives: To assess the effect of glass–ceramic coated zirconia versus alumina air-abraded zirconia on the shear bond strength (SBS) of resin cement and investigate the residual stresses present on both mechanically pre-treated surfaces. Materials and Methods: A total of 180 zirconia disks, with diameters of 10 mm and 5 mm, were divided into two groups: DCMhotbond glass–ceramic coated, followed by hydrofluoric acid etching (DCM), and alumina air-abraded (AB). All mechanically pre-treated disks were conditioned with G-Multi Primer and bonded using G-Cem Linkforce Cement. Ninety specimens were immersed in distilled water for 24 h and subsequently allocated into three groups based on aging conditions (n = 15/subgroups): immediate testing, 5000 thermal cycles, and 10,000 thermal cycles. Then, the shear bond strength was assessed, and the obtained data were subjected to analysis using a two-way ANOVA, followed by a one-way ANOVA and Tukey's HSD post hoc test (α = 0.05). The residual stresses present on both mechanically pre-treated surfaces were examined using X-ray diffraction analysis. Results: The mean SBS values of the DCM and AB groups showed no significant difference under each aging condition. The SBS of DCM groups was not affected by thermal cycles, whereas the SBS of AB groups exhibited a significant decrease following thermal cycles. Glass–ceramic coated surfaces exhibited higher compressive stresses than alumina air-abrasion. Conclusions: The DCMhotbond glass–ceramic coated zirconia showed comparable bond strength to the alumina air-abrasion technique. Clinical Relevance: The DCMhotbond glass–ceramic coating technique is a promising alternative for zirconia surface pre-treatment. However, further investigations are needed before suggesting its clinical use. [ABSTRACT FROM AUTHOR]