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, p < 0.001). CLSM showed dead-to-live ratios of SCF, SDF and Water group were 1.0 ± 0.3, 1.4 ± 0.5, and 0.2 ± 0.1 (p < 0.001; 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.

Caries prevention

Silver compounds

Antibacterial

Dentine

Fluoride

© 2025 The Authors. Published by Elsevier Ltd.