Influence of surface treatment and simulated aging on bond strengths of luting agents to zirconia

Objective: To evaluate short- and long-term shear bond strengths of 4 luting agents to zirconia following different surface treatments. Method and Materials: A total of 320 ceramic specimens fabricated from a commercial zirconium oxide ceramic (Lava) were randomly divided into 4 groups: left untreated (NOT), airborne-particle abraded (SND), Rocatec tribochemical silica/silane coated (ROC), or ground and polished (GRD). Resin composite cylinders were bonded to the zirconia specimens with resin composite luting agent RelyX ARC (ARC), universal adhesive resin composite RelyX Unicem (UNI), adhesive-phosphate-monomer-containing resin composite Panavia F (PAN), or the hybrid glass-ionomer cement RelyX Luting (LUT). Subgroups of 10 specimens were stored in distilled water (37°C) for 3 days (ST) or stored for 180 days and thermocycled for 12,000 cycles (LT/TC) before shear bond strength was tested. Statistical analyses included Kruskal-Wallis and Wilcoxon 2-sample rank sum test (a = .01). Results: Short-term shear bond strengths were higher with ROC than with SND, which were both greater than GRD or NOT. UNI revealed higher shear bond strengths than PAN, ARC, and LUT. LT / TC significantly decreased shear bond strength values. GRD and NOT produced the lowest shear bond strengths. SND and ROC significantly increased bond strength. ROC generally yielded the highest long-term shear bond strength, especially with UNI, PAN, or ARC. These were similar to SND and PAN, which revealed the highest long-term shear bond strengths. Conclusions: Surface treatment, luting agent, and storage conditions significantly influence shear bond strengths to zirconia. Artificial aging significantly reduces shear bond strengths. Airborne-particle abrasion combined with a resin composite containing adhesive phosphate monomers or tribochemical silica / silane coating combined with any of the tested resin composite luting agents provides superior long-term shear bond strength values. Keywords: bond strength, ceramic, luting agent, surface treatment, zirconia