In situ formation of Ca-Ag hybrid nanoparticles for multifunctional reconstruction of the resin-dentin interface.

OBJECTIVES: The hybrid layer formed during dentin bonding remains susceptible to degradation. This study aimed to develop a CaCl₂/AgF treatment strategy for in situ deposition of Ca-Ag hybrid nanoparticles within the demineralized dentin matrix (DDM) and to evaluate its effects on interface-confined water regulation, antibiofilm activity, mineral deposition, and ultimately bonding durability. MATERIALS AND METHODS: DDM was sequentially treated with CaCl₂ and AgF solutions. Interface-confined water regulation was assessed by surface potential, water uptake, and thermogravimetric analysis (TGA). Antibiofilm activity against Streptococcus mutans (S. mutans) and saliva-derived microcosm biofilms was evaluated by confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM). Mineral deposition was examined by transmission electron microscopy (TEM) and selected area electron diffraction (SAED). Adhesive infiltration, nanoleakage, and microtensile bond strength (1 day and 12 months) were tested. RESULTS: Ca-Ag deposition was associated with reduced interfacial hydration, as indicated by reduced surface potential, decreased water uptake, and lower mass loss below 200 °C in TGA. It inhibited biofilm formation and disrupted established biofilms. Enhanced mineral deposition occurred within 1 h in the Ca-Ag group, with SAED patterns showing crystalline mineral phases, whereas controls remained unmineralized. Enhanced adhesive infiltration, reduced nanoleakage, and improved 12-month bond strength were observed. CONCLUSIONS: Sequential CaCl₂/AgF treatment induced the in situ deposition of Ca-Ag hybrid nanoparticles within the DDM, which was associated with reduced interfacial hydration, antibiofilm activity, mineral deposition, and improved bonding performance in vitro. CLINICAL SIGNIFICANCE: This in vitro study suggests that CaCl₂/AgF treatment may represent a potential strategy for improving resin-dentin interface stability. Further investigations are required to evaluate its clinical applicability.