Effect of Air-Abrasion Dentin Pre-Treatment on Shear Bond Strength of Contemporary Dental Adhesive Systems

The present study aimed to evaluate the effect of air-abrasion as a dentin pre-treatment on the bond strength of contemporary adhesive systems. The bonding approaches included etch-and-rinse (ER), self-etch (SE) and universal (UN) adhesive systems, with the latter applied in both ER and SE modes. Twenty-eight third molars were used, each sectioned in four parts. All specimens were embedded in acrylic resin, ground with silicon carbide papers, and divided into eight experimental groups (n = 14) based on the combination of surface pre-treatment (air-abrasion or none) and adhesive approach. Subsequently, a resin cylinder was bonded to each surface following the respective treatment. Shear bond strength (SBS) was evaluated at a cross-head speed of 0.7 mm/min using a shear-testing machine (OM100 Odeme, Luzerna, Brazil). The data were analyzed with one-way ANOVA and Tukey’s post hoc test. No statistically significant increase in SBS after air-abrasion of dentin was found for any of the experimental groups (p > 0.05). Among the adhesive strategies, the ER system presented higher SBS values (32.81 ± 9.04 MPa) than the UN adhesive applied in SE mode (21.68 ± 5.85 MPa) (p < 0.05). Mixed failures were the most common failure type across all groups. In particular, 20.5% of the specimens exhibited adhesive failure, 14.3% cohesive failure within resin composite, 12.5% cohesive failure within dentin and 52.7% specimens demonstrated mixed failure types. Dentin pre-treatment with air-abrasion using 29 μm Al2O3 did not significantly increase the SBS of the three tested contemporary adhesive systems; however, the choice of adhesive strategies influenced the SBS outcomes.