Effect of Glass–Ceramic Spray Deposition on Bond Strength to Zirconia

Objective: To evaluate the effect of glass–ceramic spray deposition and artificial aging on the shear bond strength (SBS) of a resin cement to zirconia. Materials and Methods: One hundred Y-TZP zirconia specimens were assigned to five groups (n = 20): airborne-particle abrasion (APC, control), lithium disilicate spray coating (LC), glaze paste (GP), and two glaze spray systems (ES and NS). APC specimens were air-abraded, whereas coated groups were etched with 5% hydrofluoric acid. All specimens received a silane/MDP ceramic primer application and were bonded with dual-cure resin cement. Half of the specimens were tested after 24 h and half after thermocycling (10,000 cycles). Data were analyzed using a two-way ANOVA and Tukey's test (α = 0.05). Results: Surface treatment and aging significantly affected SBS (p < 0.001). Thermocycling reduced SBS in all groups. APC showed the highest SBS under both conditions, followed by LC. No differences were observed among glaze groups after thermocycling. Conclusions: APC showed the highest short- and long-term bond strength among all groups, followed by LC, which demonstrated better bonding performance than glaze-based systems. After thermocycling, SBS decreased in all groups, and LC revealed about half the SBS recorded for APC.