Nanostructured Dental Composites And Adhesives With Antibacterial And Remineralizing Capabilities For Caries Inhibition

Secondary caries is a frequent reason for dental restoration failure, resulting from acidogenic bacteria and their biofilms. Our objectives were to develop the first-generation of bioactive nanocomposites and nanostructured bonding agents with antibacterial and remineralizing capabilities. Such a combination of capabilities is highly promising to inhibit caries but unavailable in current composites and adhesives. Nanoparticles of amorphous calcium phosphate (NACP) and silver (NAg), and quaternary ammonium dimethacrylate (QADM) were synthesized and incorporated into composites and adhesives. Specimens were inoculated with biofilms. NACP+QADM nanocomposite had flexural strength matching those of commercial controls, while reducing biofilm colony-forming units (CFU) by threefold. Metabolic activity and lactic acid production of biofilms adherent on NACP+QADM were much less than those on commercial composites. Antibacterial properties of NACP+QADM were maintained after water-aging. New bonding agents reduced lactic acid and CFU of total microorganisms, total streptococci, and mutans streptococci by an order of magnitude, without adversely affecting dentin bond strength, compared to commercial control. The new class of nanocomposites and adhesives with strong and durable antibacterial properties, together with the previously-reported calcium phosphate ion release properties, is promising for caries-inhibiting restorations.