Effect of air-abrasion and air-polishing powders on dentin hydraulic conductance before and after acid challenge.

Air-polishing and air-abrasion powders may contact exposed dentin, but their effects on fluid transport after acid exposure remain unclear. This in vitro study compared hydraulic conductance before and after powder application and acid challenge. Forty-two 1.0-mm coronal dentin discs were allocated (n = 7/group) to calcium sodium phosphosilicate bioactive glass (Sylc Powder), silica-coated aluminum oxide (CoSil Powder), sodium bicarbonate (AquaCare Sodium Bicarbonate), erythritol with 0.3% chlorhexidine (AIRFLOW PLUS Powder), sodium bicarbonate (AIRFLOW CLASSIC Powder), or untreated control. After 6% citric-acid conditioning for 10 min, baseline conductance was measured. Powders were applied for 15 s, and conductance was measured immediately. After 2% citric acid for 2 min, conductance was remeasured immediately. At 3 psi, 50-µL water transit was normalized to exposed area and pressure and expressed as µL·min⁻¹·cm⁻²·cmH₂O⁻¹. Data were analyzed by two-way mixed repeated-measures analysis of variance, stage-specific Tukey comparisons, and two-sided paired t tests with Holm adjustment. Stage (F(2, 72) = 117.95, p < 0.001) and the group-by-stage interaction (F(10, 72) = 11.77, p < 0.001) were significant. Conductance decreased from baseline in all five active groups (Holm-adjusted p ≤ 0.003) but not in the control (p = 0.681). After acid challenge, Sylc Powder remained lower than all other groups (p ≤ 0.014). Scanning electron microscopy provided illustrative morphology. Under this 15-s application and 2-min challenge protocol, responses depended on powder and stage; bioactive glass produced the most persistent reduction, whereas the other powders returned toward baseline.