Silver phosphate as an antimicrobial and remineralizing agent in orthodontic resins

The high incidence of white spot lesions among orthodontic patients highlights the need for strategies to prevent mineral loss in high-risk areas. Silver phosphate (Ag₃PO₄) nanoparticles offer multifunctional potential by inhibiting biofilm formation and increasing phosphate availability. This study aimed to develop an orthodontic resin with the addition of Ag₃PO₄ and evaluate its physicochemical and biological properties.

Ag₃PO₄ nanoparticles were synthesized through coprecipitation and characterized. The particles were incorporated into orthodontic resins at concentrations of 0.5, 1, and 2 wt%. Physicochemical and biological properties were assessed with polymerization kinetics, microhardness, cytotoxicity, shear bond strength, antibacterial activity against Streptococcus mutans, and mineral deposition over time.

Ag₃PO₄ reduced bacterial biofilm and enhanced mineral deposition. The G_1% showed significant antibacterial activity immediately after application, whereas the G_2% maintained effectiveness after 6 months. Microhardness values remained stable, although a higher concentration slightly decreased bond strength. No cytotoxicity was observed at any concentration, and phosphate deposition was detected with higher intensity on the surface of specimens that were loaded with higher concentrations of Ag₃PO_4. CONCLUSIONS: Ag₃PO₄ particles were successfully produced and incorporated into orthodontic resins, with the 1 wt% concentration maintaining the resin's physical properties and bonding ability without cytotoxic effect. The addition of Ag₃PO₄ promoted the antimicrobial effect and phosphate deposition, supporting a multifunctional strategy to control biofilm formation and promote phosphate deposition around orthodontic appliances.