Is air abrasion effective as a surface pretreatment for enamel, dentin, and IDS-treated dentin?

This study investigated the effects of air abrasion with different abrasive particles on the surface roughness and bond strength of resin-based luting agents to enamel and dentin, including dentin surfaces treated with immediate dentin sealing (IDS). Bovine teeth were used, and four types of substrates were prepared: enamel, untreated dentin, dentin treated with IDS using an adhesive, and dentin treated with IDS using a resin composite. Air abrasion was performed using aluminum oxide (29 µm, 53 µm) or bioactive glass at 0.3 MPa for 10 s from a 10-mm distance prior to the bonding procedure. Acid-etched enamel specimens were included for comparison. A 2.4 mm cylindrical mold was set on the surface and filled with resin-based luting agents, followed by light curing. Surface roughness (Ra) after the surface pretreatments, and the shear bond strength were evaluated. The number of repetitions was set to 15. Statistical analyses were conducted using one-way ANOVA and Tukey's post hoc test (α = 0.05). Acid etching produced the highest bond strength on enamel, although air abrasion with 29-µm alumina resulted in comparable values. In contrast, air abrasion increased surface roughness but did not enhance bond strength on either untreated dentin or IDS-treated dentin, regardless of whether an adhesive or resin composite was used. These findings suggest that while 29-µm alumina abrasion is a viable alternative to acid etching on enamel when acid use is contraindicated, its effectiveness appears to be substrate-dependent and may not facilitate improved bonding to dentin or IDS-treated dentin despite increased roughness.