Influence of Quercetin and tt-Farnesol Enrichment on Physicochemical Properties of a Universal Adhesive System

Abstract

This study investigated the impact of natural compound enrichment, specifically quercetin and trans, trans-farnesol (tt-farnesol), on the physicochemical properties of a universal adhesive system. A preliminary DPPH assay was conducted to determine the optimal concentrations of quercetin (0.24 mg/mL) and tt-farnesol (1.43 mg/mL) based on their radical scavenging abilities. These compounds were then incorporated into the adhesive system. Specimens (n = 5; 7 mm × 1 mm) of the adhesive system, both with and without the added compounds, were prepared and tested for water sorption, solubility, Knoop hardness, and softening percentage. Water sorption and solubility were measured after immersion in deionized water for 7 days, and Knoop hardness was measured before and after immersion in 75% ethanol. Softening percentage was calculated based on changes in hardness. Data on water sorption, solubility, and percentage of softening were submitted to the Student’s t-test (α = 5%) while Knoop hardness values were submitted to the Mann–Whitney test (α = 5%). Both quercetin and tt-farnesol exhibited important antioxidant activity (85.5% and 82%, respectively). Water sorption was similar for both groups (p > 0.05) but the experimental adhesive had a significantly higher solubility, lower hardness, and higher softening. The incorporation of quercetin and tt-farnesol into a universal adhesive system detrimentally affects its essential physicochemical properties, compromising its performance.