Antibacterial and mineralising properties of silver complex fluoride on enamel caries: An in vitro study

This study aimed to investigate the antibacterial and mineralising effects of silver complex fluoride (SCF) on enamel.

Sound human enamel blocks were prepared and subjected to Streptococcus mutans-induced demineralisation to create artificial caries. Blocks were treated with SCF, 38% silver diamine fluoride (SDF), or deionised water and underwent a 21-day pH-cycling. Biofilm morphology, viability, and quantification were analysed using scanning electron microscopy (SEM), confocal laser scanning microscopy (CLSM), and colony-forming unit (CFU) counting. Remineralisation effects were assessed by SEM, micro-computed tomography (micro-CT), Knoop microhardness, and X-ray diffraction (XRD).

SEM images showed dense bacterial biofilm on water-treated enamel, but minimal growth on SCF- or SDF-treated surfaces. CLSM indicated higher dead/live cell ratios in SCF (0.75 ± 0.22) and SDF (0.83 ± 0.25) groups than water (0.43 ± 0.22; p < 0.001). Log CFU values for SCF, SDF, and water were 6.90 ± 0.09, 6.74 ± 0.23, and 7.78 ± 0.13, respectively (p < 0.001, SCF, SDF < Water). Lesion depths (μm) were 91 ± 36, 89 ± 24, and 186 ± 34 (p < 0.001; SCF, SDF < Water), while mineral loss (gHA pcm⁻³) was 0.43 ± 0.13, 0.40 ± 0.14, and 1.32 ± 0.21 (p < 0.001; SCF, SDF < Water) for SCF, SDF, and water, respectively. Knoop hardness was significantly higher in SCF (70 ± 2) and SDF (72 ± 7) than water (25 ± 6; p < 0.05). XRD confirmed well-crystallised hydroxyapatite in SCF- and SDF-treated enamel but not in water-treated samples.

SCF demonstrates antibacterial and mineralising properties comparable to SDF.

Adoption of SCF may expand silver-based caries prevention by improving patient acceptance without compromising appearance.