Influence of elapsed time between airborne-particle abrasion and bonding to zirconia bond strength

The airborne-particle abrasion of zirconia with alumina particle (APA) has been reported to result in the durable bonding of appropriate adhesive luting systems. However, whether a delay between APA and the application of the adhesive luting material might affect the resulting bond strength and its durability is unknown.

A total of 140 disc-shaped zirconia specimens were divided according to the elapsed time between the APA of zirconia and its bonding into 5 test groups (15 min, 1 h, 4 h, 24 h, and 72 h). The specimens were airborne-particle abraded with 50-μm Al₂O₃, and then stored at room temperature according to the test group (n = 28/group). Surface free energy (SFE) was measured for 12 specimens per group using a goniometer. For each group 16 Plexiglas tubes filled with composite resin were bonded to the zirconia specimens with an adhesive luting resin (Panavia 21). Tensile bond strength (TBS) was tested for subgroups of 8 specimens after water storage for 3 days and for 150 days with 37,500 thermal cycles.

SFE decreased significantly within 24 h after APA. TBS after 3 days of water storage ranged from 38.3 (1 h) to 28.4 MPa (24 h) and after 150 days with thermocycling from 38.3 (15 min) to 24.8 MPa (24 h).

Based on these results, the time between the APA of zirconia and the application of adhesive materials should be minimized when bonding nonretentive zirconia restorations clinically.