Development and characterization of self-etch adhesive system containing curcumin anchored to nanosilica on the bond strength to sound and caries-affected dentin

To evaluate the effects of incorporating curcumin anchored to nanosilica (CAN) into an experimental adhesive (EXP) on flexural strength, antimicrobial potential, bacterial collagenase activity, and bond strength (BS) to dentin. A commercial adhesive and EXPs containing 0 %, 1 %, 2.5 %, and 5 % CAN were tested. Cavities were prepared in 160 M (n = 20), half with induced caries. After adhesive application, cavities were restored with composite, sectioned into sticks, and stored at 37 °C for 24 h, 6 months, and 1 year before BS testing. Fracture patterns were analyzed using scanning electron microscopy, and bacterial collagenase resistance was assessed. EXPs exhibited similar flexural strength and antimicrobial activity (p > 0.05), both higher than commercial (p < 0.05). In caries-affected dentin, CAN0 % and CAN1 % had the lowest BS (p < 0.05) after 24 h, while CAN1 % and CAN2.5 % exhibited the lowest BS (p < 0.05) after 6 months. In sound dentin, CAN2.5 % showed the lowest BS (p < 0.05) after 6 months and remained the lowest after 1 year in both substrates. In sound dentin, adhesive fractures were more common in commercial and CAN2.5 % after 24 h, whereas mixed fractures predominated in CAN0 % and CAN1 %. With aging, mixed fractures became more frequent. In caries-affected dentin, adhesive fractures increased over time. Aging caused hybrid layer degradation, with Whitlockite crystals in Exps. All adhesives showed biodegradation. Incorporating CAN into EXP did not flexural strength but also did not enhance antimicrobial potential or BS. High CAN concentrations may have compromised BS over time. EXP showed no effect against bacterial collagenase.