The aim of this study was to evaluate the degree of conversion and bond strength of a commercial dental adhesive modified by the incorporation of quercetin, resveratrol (RES), and Brazilian red propolis (BRP). Single Bond 2 adhesive (3M ESPE) was modified by adding BRP, quercetin, and RES, separately, at 20 µg/mL, 250 µg/mL, and 500 µg/mL, respectively. The degree of conversion (DC) was measured using near-infrared spectroscopy 24 h after photopolymerization. resin-dentin Microtensile bond strength (µTBS) measurements were carried out after 1 day and 1 year. Student’s t test and ANOVA with Tukey’s test were used for data analysis (α = 0.05). The DC of the tested adhesives remained adequate for this category of material, with a slight increase in the DC of adhesives with quercetin and BRP (P > 0.05). Comparisons between µTBS measurements made at 1 day and 1 year showed that, contrary to the control group, µTBS values for all modified adhesives were maintained after 1 year in distilled water (P > 0.05). These findings suggest that quercetin, RES, or BRP might be useful in adhesive dentistry to help improve hybrid layer resistance.
