Bonding of Resin Cement to Zirconia with High Pressure Primer Coating

This study investigates the effect of air-drying pressure during ceramic primer coating on the bonding of zirconia to resin and the surface characteristics of primed zirconia. Two ceramic primers, Clearfil Ceramic Primer and Z-Prime Plus, were applied to air-abraded zirconia and dried at four different air pressures (0.1–0.4 MPa). Subsequently, the primed zirconia specimens were bonded with a resin-based luting agent, with micro-shear bond strengths evaluated after water storage or thermocycling. Failure modes of fractured specimens were examined using scanning electron microscopy. The study assessed the effects of air pressure on primer layer thickness and surface roughness employing various characterization techniques. Results indicated that Clearfil Ceramic Primer dried at 0.3 and 0.4 MPa achieved significantly higher micro-shear bond strengths compared to lower pressure conditions. In contrast, Z-Prime Plus showed superior bond strength when dried at 0.2 MPa. Moreover, increased air-drying pressure correlated with reduced film thickness and rougher surface characteristics for both primers. These findings demonstrate that air-drying pressure significantly influences the bond strength and durability of resin-zirconia interfaces.