Ion Release and Antimicrobial Properties of Preventive Agents

Objectives: Silver Diamine Fluoride (SDF) is a topical solution recently approved by FDA to desensitize tooth roots in the USA, but is utilized internationally for caries treatment and prevention. Our aim was to evaluate pH and ion release of SDF in comparison to a polymeric sealant. Additionally, we sought to determine the antimicrobial effects of these agents.
Methods: 38% SDF (Elevate Oral Care, West Palm Beach, USA) and Clinpro Sealant (3M, St. Paul, USA) were applied to 5-mm diameter by 2-mm thick hydroxyapatite (HA) and PMMA discs and incubated 37°C in ultrapure water (n=40). Fluoride ion release (ppm) and pH was measured via ion-specific-electrodes eight times through 14 days. For antimicrobial testing, S. mutans (UA159) colonies were inoculated into brain-heart-infusion medium and incubated overnight. Diluted bacteria-laden medium was introduced to wells containing each agent and incubated for 24 hours (n=3). The optical density (OD600) of planktonic cells in solution was measured. Surface bacteria were sonicated and plated to obtain CFU/mL. Results were analyzed with an ANOVA.
Results: SDF on PMMA and HA showed initial ion release rates of 40.0 and 13.4 ppm/hr, respectively. The sealant on PMMA had an initial release rate of 1.06 ppm/hr compared to that on HA at 0.34 ppm/hr. The concentration of fluoride released was greater for SDF at all timepoints. Values for pH ranged from 3.48 to 7.16 and from 6.23 to 8.14 for the sealant and SDF, respectively. pH Values decreased over time on PMMA, but increased on HA. Microbiological results revealed that SDF showed definite antibacterial effects as compared to the sealant on both liquid and surface cultures.
Conclusions: Fluoride release, pH, and antibacterial activity are all implicated in outcomes important to preventative dentistry. SDF showed greater fluoride release and antimicrobial activity, as compared to the sealant.