Evaluation of Physicochemical and Mechanical Properties of a Modified Adhesive System by Resveratrol Incorporation

This study aimed to evaluate the physicochemical and mechanical properties of a modified adhesive system containing resveratrol by assessing its microtensile bond strength (µTBS), degree of conversion (DC), mini-flexural strength (MFS), and antibacterial activity. The modified etch-and-rinse adhesive system was prepared by resveratrol (RES) incorporation in different concentrations: adhesive with 0.5% RES (RES0.5), adhesive with 1% RES (RES1), adhesive with 2% RES (RES2), and adhesive with no RES incorporation (RES0-control group). The µTBS test was conducted on 40 human molars with dentin exposure, which were etched, bonded with the adhesives (<i>n</i> = 10), and restored with resin composite. Fourier Transform Infrared Spectroscopy (FTIR) measured the DC for the MFS; ten adhesive sticks were made for each group. Antibacterial activity was assessed using colony-forming unit (CFU) counts. For µTBS, no difference between the groups was found (mean ± SD): RES0.5-42.93 ± 15.49^A; RES1-42.61 ± 13.97^A and RES2-39.43 ± 9.14^A; RES0-41.01 ± 2.64^A. The DC (% ± SD) of the experimental groups was similar: RES0.5-81.02 ± 1.95^A; RES1-76.02 ± 9.00^A; RES2-58.86 ± 15.94^A; RES0-77.75 ± 3.22^A. For MFS (mean ± SD): RES0.5-33.14 ± 13.83^A; RES1-31.1 ± 12.21^A; RES2-19.72 ± 5.43^B; RES0-29.72 ± 11.95^A. For CFU (mean ± SD): RES0.5-0.67 × 10⁷ ± 0.37^B; RES1-0.68 × 10⁷ ± 0.34^B; RES2-0.60 × 10⁷ ± 0.02^C; RES0-0.75 × 10⁷ ± 0.03^A. The incorporation of resveratrol into the adhesive system at low concentrations (0.5 and 1%) does not alter the bond strength of the adhesive interface, the degree of conversion, or the flexural strength. Additionally, both concentrations exhibited antibacterial properties by reducing the colony-forming units of <i>S. mutans</i>.