Development of a novel silver complex fluoride for caries management: an in vitro study

The objective of this study is to develop a novel antibacterial and non-discolouring silver complex fluoride (SCF) for caries management.

SCF was synthesized by reacting 1,3,5-triaza-7-phosphaadamantane (PTA) with silver fluoride and characterised by electrospray ionization mass spectrometry. Silver and fluoride concentrations were measured by inductively coupled plasma atomic emission spectroscopy and fluoride ion-specific electrode. Alkalinity was measured using a pH meter. Cytotoxicity was assessed by determining the half maximal inhibitory concentration (IC₅₀) against the human gingival fibroblasts (HGF-1) and stem cells from human exfoliated deciduous teeth (SHED). Demineralised human dentine blocks were treated with SCF, incubated for 7 days with Streptococcus mutans, and assessed for antibacterial activity and discolouration. Biofilm kinetics and viability were analysed via colony-forming unit (CFU) counts and confocal laser scanning microscopy (CLSM). Dentine discolouration was quantified using colour spectrophotometry. Controls included 38% silver diamine fluoride (SDF; positive) and water (negative).

At 180 days, 55% SCF solution contained 127,498 ± 3,535 ppm silver and 27,215 ± 118 ppm fluoride, with a pH of 10. SCF demonstrated higher IC₅₀ values compared to SDF in HGF-1 (35.5 ± 1.1 ppm vs. 17.7 ± 0.5 ppm; p < 0.001) and SHED (95.5 ± 0.1 ppm vs. 6.4 ± 0.3 ppm; p < 0.001). Log CFU counts for the SCF, SDF, and Water groups were 4.2 ± 0.2, 3.8 ± 0.4 and 5.2 ± 0.2 (SCF, SDF Water). Spectrophotometric analysis revealed ΔE values of SCF, SDF and Water groups were 5.8 ± 3.3, 73.0 ± 17.6, and 5.3 ± 2.7 (p < 0.001; SCF, Water < SDF).

A novel SCF solution with potent antibacterial efficacy and minimal discolouration was successfully developed.

SCF demonstrates promising potential for clinical use in caries management, combining antimicrobial action with aesthetic preservation.