Bond Strength of Resin Cement to Zirconia after Surface Treatments

Objectives: Although air-abrasion with glass beads may reportedly be less likely to weaken cubic-containing zirconia, it may not roughen the zirconia surface as well as aluminum oxide and therefore result in lower bond strength of resin cement. Objective: The purpose of this study was to evaluate the effects air abrasion on the shear bond strength of resin cement to three types of zirconia: 5Y-PSZ, Katana UTML, Shade A2, Noritake; 4Y-PSZ, Katana STML, Shade A2; and 3Y-TZP, Katana ML, Shade 1.5-2.
Methods: Methods: Thirty block specimens (8x8x3.5mm) were milled out of each zirconia material and mounted in plastic pipe. Ten specimens of each of the zirconia materials were air-abraded (Basic Quattro IS, Renfert) using 50μm aluminum-oxide particles (Ney, Dentsply Ceramco) at 2.0 bar for 10 seconds; ten specimens were abraded using 80 μm glass beads (Williams Glass Beads, Ivoclar Vivadent); and ten specimens served as a control and received no surface treatment. A 10-MDP primer (Z-Prime Plus, Bisco) was applied to the top surface of the zirconia specimens. Composite discs (Z250, 3M ESPE) were bonded using a resin cement (NX3, Kerr) and light cured. The specimens were stored in 37°C distilled water for 24 hours and then thermocycled for 2,500 cycles at 5°C and 55°C (Sabri Dental Enterprise). The specimens were loaded in shear on a universal testing machine (Instron). Data were analyzed with one- and two-way ANOVAs/Tukey post hoc tests (alpha=0.05).
Results: Results: A significant difference in shear bond strength was found based on surface treatment (p<0.001), but not on zirconia type (p=0.132), with no significant interaction (p=0.98). See table.
Conclusions: Conclusions: Air-abrasion with aluminum oxide created significantly greater bond strength of the resin cement to all three zirconia types compared to air-abrasion with glass beads or no surface treatment, which were not significantly different from each other.