In vitro evaluation of antibacterial activity and biocompatibility of silver-doped fluorapatite glass-ceramic/zirconia gradient composites.

OBJECTIVE

This study aims to fabricate graded silver-doped fluorapatite (Ag-FAp) glass-ceramics/zirconia composites with interfacial fracture resistance and bonding stability, whose biological activity and antibacterial performance can be improved by varying Ag⁺ dopant concentrations.

METHODS

Ag-FAp glass-ceramics (0, 0.25%, 0.5%, 0.75% and 1% Ag⁺ mass fractions) were prepared via melt quenching. Co-sintering of the Ag-FAp glass-ceramics with porous zirconia green bodies, afforded a gradient composite structure. The microstructure, thermal stability, interfacial fracture resistance, bonding stability, ion release, biocompatibility and antibacterial activity were comprehensively characterised.

RESULTS

X-ray diffraction results confirmed that Ag⁺ formed a solid-solution in the FAp lattice, preserving its hexagonal structure. The finest grain morphology was obtained with 0.75% Ag⁺. Particle agglomeration was apparent with 1% Ag⁺. The Ag-FAp glass-ceramics exhibited excellent thermal stability, confirming their suitability for zirconia sintering. The porous structure of the zirconia green body facilitated infiltration of the Ag-FAp glass-ceramics, forming stable, high-strength interfaces. Ag⁺ release increased with increasing Ag⁺ doping, whereas F⁺ release maintained a steady state. Importantly, the 0.5 mol% Ag⁺-doped sample achieved a favourable trade-off between biocompatibility and in vitro antibacterial activity.

CONCLUSIONS

The as-prepared Ag-FAp/zirconia composites possessed a stable interfacial structure with desirable ion release behaviour. The composites exhibited favourable in vitro biocompatibility and potent antibacterial activity against typical oral pathogens, providing an experimental basis for their clinical application in preventing secondary caries.

CLINICAL RELEVANCE: The Ag-FAp/zirconia composites enable the transition of dental restorations from passive repair to active caries prevention, with potential clinical application.