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 (n = 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 ± 15.49A; RES1—42.61 ± 13.97A and RES2—39.43 ± 9.14A; RES0—41.01 ± 2.64A. The DC (% ± SD) of the experimental groups was similar: RES0.5—81.02 ± 1.95A; RES1—76.02 ± 9.00A; RES2—58.86 ± 15.94A; RES0—77.75 ± 3.22A. For MFS (mean ± SD): RES0.5—33.14 ± 13.83A; RES1—31.1 ± 12.21A; RES2—19.72 ± 5.43B; RES0—29.72 ± 11.95A. For CFU (mean ± SD): RES0.5—0.67 × 107 ± 0.37B; RES1—0.68 × 107 ± 0.34B; RES2—0.60 × 107 ± 0.02C; RES0—0.75 × 107 ± 0.03A. 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 S. mutans.