Facile Ag+-assisted bonding strategy to build a low-defect hybrid layer with intrinsic antibacterial and enzymolysis inhibitory properties

Abstract

As the most widely used material for dental tissue repair, dental resin composites face durability challenges, and their longevity critically depends on the hybrid layer's integrity. Incomplete adhesive infiltration within demineralized dentin matrix (DDM) creates structural defects in this layer, rendering it vulnerable to stress, enzymatic degradation, and bacterial invasion. These factors contribute to secondary caries, the predominant complication of resin-based restorations. Enhancing adhesive infiltration and the hybrid layer's antibacterial capacity is thus pivotal to extending the restoration lifespan. Previous studies have revealed that strong metal ion chelation can release confined water to facilitate hydrophobic monomer infiltration, significantly improving dentin bonding efficacy and durability. Therefore, in this study, leveraging the dual advantages of Ag⁺—potent chelation and antibacterial activity—we treated a DDM with Ag⁺. A brief 20-second application chemically modified the DDM, enabling confined water release, enhancing adhesive infiltration and conferring a durable antibacterial functionality. Additionally, matrix metalloproteinases (MMPs) activated during bonding were effectively inhibited. Notably, subsequent light irradiation reduced Ag⁺ to metallic silver, enhancing structural stability by orders of magnitude. This approach successfully established a stable low-defect hybrid layer. This strategy offers a clinically viable solution for achieving durable dentin restoration with integrated antibacterial properties.