Polyphenol-functionalized silver nanoparticles promote differential remineralization and reinforcement of demineralized dentin

Abstract Silver nanoparticles (AgNPs) have gained relevance in restorative dentistry due to their antimicrobial and remineralizing properties. However, the role of AgNPs functionalized with different polyphenols in dentin remineralization remains insufficiently understood. Objectives This study aimed to synthesize and characterize AgNPs functionalized with crosslinking polyphenols extracted from grape seed extract (GSE) and green tea leaves (GT), and to evaluate their biocompatibility and their effects on the mechanical and physicochemical properties of demineralized dentin. Methodology AgNPs were characterized by TEM, XRD, TGA, and zeta potential analysis to determine particle morphology, crystalline structure, chemical composition, and surface charge. Biocompatibility was assessed using fibroblast cytotoxicity assays. In total, 40 human mid-coronal dentin specimens were randomly assigned to four groups (n=10): Control- (sound dentin), Control+ (pH-cycled dentin without treatment), AgGSE (pH-cycled + AgGSE, 1 min), and AgGT (pH-cycled + AgGT, 1 min). Treated dentin was analyzed by ATR-FTIR, XRD, TGA, and three-point bending tests. Results Both AgNPs were successfully synthesized and exhibited high biocompatibility. AgGSE demonstrated greater dentin matrix interaction, resulting in significantly higher flexural strength (p≤0.001). In contrast, AgGT induced pronounced remineralization with increased PO4/Amide I ratio (p=0.003) and CO3/PO4 ratios (p=0.007 by TGA; p=0.03 by ATR-FTIR), consistent with carbonated apatite deposition. Conclusions Green-synthesized AgNPs functionalized with GT or GSE promoted reinforcement and remineralization of demineralized dentin through distinct mechanisms of action. These findings highlight their potential as biocompatible agents for dental therapies.