Antimicrobial Activity of Silver Diamine Fluoride on Human Periodontitis Microbiota

Objectives: Silver diamine fluoride has been used in management of dental caries and cariogenic bacteria. This study evaluated the in vitro antimicrobial effects of silver diamine fluoride on subgingival specimens from severe human periodontitis lesions.
Methods: Dilution aliquots of subgingival biofilm samples from 24 adults with severe periodontitis were mixed or not in vitro with either 38% or 19% silver diamine fluoride, inoculated onto enriched Brucella blood agar plates, and incubated anaerobically for 7 days at 37°C. Phenotypic criteria identified the following red/orange complex periodontal pathogens: Porphyromonas gingivalis, Tannerella forsythia, Prevotella intermedia/nigrescens, Parvimonas micra, Campylobacter rectus, Fusobacterium nucleatum and Streptococcus constellatus. Bacterial species recovered from silver diamine fluoride-exposed specimens were considered resistant to silver diamine fluoride, and identified using matrix-assisted laser desorption-ionization time-of-flight mass spectrometry and Bruker MALDI Biotyper analytic software.
Results: Subgingival specimen exposure to silver diamine fluoride yielded significantly lower mean total viable counts, and significantly lower total proportions of red/orange complex periodontal pathogens (mean 0.5%-0.6%), as compared to non-exposed control samples (mean 25.9%), with no significant differences found between 38% and 19% silver diamine fluoride exposure. P. micra (3 patients) and S. constellatus (1 patient) were the only red/orange complex species recovered from subgingival specimens exposed in vitro to silver diamine fluoride. Streptococcus oralis and other streptococci of low periodontopathic/cariogenic potential were the most predominant species resistant to silver diamine fluoride.
Conclusions: Silver diamine fluoride exhibited substantial in vitro antimicrobial activity against total subgingival viable counts and red/orange complex periodontal pathogens from severe periodontitis patients. The suppression of putative periodontal pathogens in subgingival biofilm specimens by silver diamine fluoride, along with its selection of silver diamine fluoride-resistant Streptococcus oralis and other streptococci associated with periodontal health, suggests a new potential therapeutic use for silver diamine fluoride in the management of human periodontal infections.