Influence of cleaning methods on zirconia ceramic bonding with long-elapsed time post-airborne-particle abrasion

To evaluate the influence of cleaning methods on bonding to zirconia ceramic over a long period after airborne-particle abrasion (APA).

A total of 140 disc-shaped zirconia specimens were divided into five groups based on the cleaning methods after a 72-hour delay between APA and bonding: A-(alcohol), V-(Ivoclean), K-(Katana Cleaner), P2-(Clearfil Ceramic Primer Plus after 72 hours), and P1-(Clearfil Ceramic Primer Plus directly after APA). The specimens were APA-treated with 50-µm alumina particles (Al₂O₃) and stored at room temperature for 72 hours (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 zirconia specimens using a self-adhesive luting resin. Tensile bond strength (TBS) was tested for subgroups of eight specimens after 3 days of water storage and 150 days with 37500 thermal cycles. Failure modes were categorized as adhesive or cohesive using light microscopy.

SFE increased significantly in groups V (68.4 mN/m) and A (61.8 mN/m) (P ≤ 0.05), but decreased in group K (33.1 mN/m) (P ≤ 0.05). TBS after 3 days of water storage ranged from 60.7 MPa in group A to 51.6 MPa in group P2 without significant difference between the tested groups (P > 0.05), and after 150 days with thermocycling, it ranged from (45.4 MPa) in group K to 33.9 MPa in group P2 with a significant difference between groups K and P2 (P ≤ 0.05).

Cleaning significantly affected the strength and durability of bonding in non-retentive zirconia restorations when there was a considerable time gap between APA and bonding.