Investigation of five α-hydroxy acids for enamel and dentin etching: Demineralization depth, resin adhesion and dentin enzymatic activity

•Surface condition of enamel and dentin of etch & rinse adhesive systems can contribute to the degradation of the dentin-resin interface.•α-hydroxy acids can produce similar bond strength while reduced micro-permeability of dentin-resin interfaces as compared to phosphoric acid.•Selective α-hydroxy acids reduced the gelatinolytic activity of the dentin matrix.•Among the α-hydroxy acids, Glycolic and Tartaric acids, are the most effective surface etchants of enamel and dentin. Surface conditioning of enamel and dentin is a key step during adhesive restorative procedures and strategies. The aim of this study was to investigate the effectiveness of five α-hydroxy-acids (AHAs) as enamel and dentin surface etchants. Enamel and dentin specimens were prepared from human molars to determine the depth of demineralization by optical profilometry (Δz), the resin bond strength to enamel and dentin (μTBS), the micro-permeability of dentin–resin interfaces, and the gelatinolytic activity of dentin matrix induced by AHAs [glycolic (GA), lactic (LA), citric (CA), malic (MI) and tartaric (TA)] and controls [phosphoric (PA) and maleic (MA)]. All acids were prepared at 35% concentration. Adhesion studies employed Adper Single Bond Plus bonding system. Data were individually processed and analyzed by ANOVA, post-hoc tests and Pearson correlations (α = 0.05). AHA exhibited statistically lower depth of demineralization of enamel and dentin (average 4 fold) than controls (p