Antimicrobial activity of silver diamine fluoride on human periodontitis microbiota

Silver diamine fluoride (SDF) has been used in management of dentinal hypersensitivity and dental caries. This in vitro study evaluated the antimicrobial effects of SDF on subgingival microorganisms from severe human periodontitis lesions. Subgingival biofilm specimens from 24 adults with severe periodontitis were mixed in vitro with 19% or 38% SDF or left untreated (n = 24 per group) and then inoculated on enriched Brucella blood agar with anaerobic incubation. Selected red- and orange-complex periodontal pathogens were phenotypically identified in the subgingival specimens, including Porphyromonas gingivalis, Tannerella forsythia, Prevotella intermedia/nigrescens, Parvimonas micra, Campylobacter rectus, Fusobacterium nucleatum, and Streptococcus constellatus. Other microbial species recovered from SDF-treated specimens were identified using matrix-assisted laser desorption- ionization time-of-flight mass spectrometry. The SDF-treated specimens yielded significantly lower mean total viable counts and significantly lower mean total cultivable proportional levels of red- and orange-complex periodontal pathogens (0.5%-0.6%) than did untreated specimens (25.9%) (P < 0.001). The only red- and orange-complex species recovered from SDF-treated specimens were P micra (3 patients) and S constellatus (1 patient). The predominant cultivable isolates from SDF-treated specimens were Streptococcus oralis and other streptococci of relatively low periodontopathic and cariogenic potential. No statistically significant in vitro antimicrobial differences were found between 19% and 38% SDF against subgingival biofilm specimens. In this experiment, SDF exhibited substantial in vitro antimicrobial activity against putative periodontal pathogens from severe periodontitis lesions. The suppression of red- and orange-complex periodontal pathogens in subgingival biofilms by SDF treatment, along with the selection of SDF-resistant Streptococcus species that are associated with periodontal health, suggests a potential new therapeutic use for SDF in the management of human periodontal infections.