Self-assembled silk fibroin as an interfacial reinforcer: A synergistic strategy with amorphous calcium phosphate for durable dentin bonding

The limited longevity of dentin bonding interfaces remains a significant challenge in dentistry, primarily due to the degradation of the hybrid layer. Incomplete penetration of dental adhesives leaves demineralized dentin collagen vulnerable to enzymatic degradation and mechanical stress. While existing approaches offer temporary solutions, dentin bonding still faces incomplete and unsustained protection for the critical interfaces. In this study, we explored an innovative dual-action biomimetic strategy combining silk fibroin (SF) and amorphous calcium phosphate (ACP) to address long-term stabilization of the dentin-adhesive interface. SF rapidly formed self-assembled fibrous network in demineralized dentin collagen. While 0.1 % and 1 % SF maintained high microshear bond strength (μSBS) values after 10,000 thermocycles, performance declined after 30,000 thermocycles (<i>P</i> < 0.05). Nanoleakage patterns progressed from discrete dots (10,000 thermocycles) to continuous lines (30,000 thermocycles). Combinations of 0.1 %SF+1 %ACP and 1 %SF+1 %ACP preserved high μSBS values after 30,000 thermocycles (<i>P</i> > 0.05), minimized nanoleakage and enzymatic activity, and maximized surface microhardness (<i>P</i> < 0.05). X-ray diffraction confirmed enhanced mineralization in these synergistic groups. The synergistic SF/ACP combination establishes a durable bond interface through a dual mechanism: the SF network reinforces the collagen matrix against degradation, while ACP provides a source for interfacial remineralization. This biomimetic strategy represents a promising advance for achieving long-term stability in resin-dentin bonds.