Novel Bioactive Nanocomposite Inhibiting Oral Microcosm Biofilms and Periodontitis-related Pathogens

Objectives: Objectives. Secondary caries remains a primary reason for restoration failures. In addition, root caries is increasing as the population ages; Class V restorations with subgingival margins are difficult to clean and often lead to periodontitis. The objectives of this study were to develop a nanocomposite containing dimethylaminohexadecyl methacrylate (DMAHDM) and nanoparticles of amorphous calcium phosphate (NACP), and investigate the inhibition of dental plaque microcosm biofilms and periodontitis-related biofilms for the first time.
Methods: Methods. Ethoxylated bisphenol A dimethacrylate (EBPADMA) and pyromellitic glycerol dimethacrylate (PMGDM) were used to form the resin. DMAHDM, NACP, and glass particles were incorporated at 3wt%, 20wt% and 50wt%, respectively. Dental plaque microcosm biofilms were tested using human saliva as inoculum. Six periodontitis-related pathogens were tested: P. gingivalis, P. intermedia, P. nigrescens, A. actinomycetemcomitans, F. nucleatum and E. faecalis. Colony-forming units (CFU), live/dead assay, biomass, and polysaccharide production by biofilms were determined.
Results: Results. Adding 3% DMAHDM to composite did not affect flexure strength and elastic modulus which were similar to commercial control composite (p>0.1). Human saliva microcosm biofilm CFU on DMAHDM composite were three orders of magnitude less than that without DMAHDM (p<0.05). For periodontal pathogens, DMAHDM composite had biofilm CFU three orders of magnitude less than that without DMAHDM. P. gingivalis biofilm CFU was 10⁹/disk without DMAHDM; it decreased to less than 10⁶/disk on composite with DMAHDM (p<0.05). P. intermedia was reduced from approximately 10¹⁰ to 10⁷ via DMAHDM (p<0.05). Biofilm biomass and polysaccharide were also greatly reduced via DMAHDM (p<0.05). The killing efficacy of DMAHDM composite against the six species was: E. faecalis<F. nucleatum<A. actinomycetemcomitans<P. gingivalis.
Conclusions: Conclusions. The novel DMAHDM-NACP nanocomposite showed strong inhibiting effects against human saliva microcosm biofilm and periodontitis-related pathogens. This nanocomposite is promising to reduce recurrent caries in composite restorations, and as Class V restorations to combat periodontitis.