Antibacterial and demineralisation-inhibiting properties of silver complex fluoride on dentine caries: an in vitro study

The objective of this study was to investigate the antibacterial and demineralisation-inhibiting effects of a non-discolouring silver complex fluoride (SCF) on artificial dentine caries. Dentine blocks with artificial carious lesions were treated with SCF, silver diamine fluoride (SDF, as positive control), and water (as negative control). Then the blocks underwent Streptococcus mutans biofilm and pH–cycling for 7 days. The morphology, viability and growth kinetics of the biofilm were evaluated by scanning electron microscopy (SEM), confocal laser scanning microscopy (CLSM) and colony-forming unit (CFU) counting, respectively. The dentine blocks’ dentine surface morphology, lesion depths and mineral loss, chemical structure and crystal characteristics were determined using SEM, micro-computed tomography, Fourier transform infrared (FTIR), and X-ray diffraction (XRD), respectively. One-way analysis of variance with the Bonferroni post hoc test was performed to assess and compare the data. SEM revealed confluent bacterial growth covering the surface of dentine treated with water but not SCF and SDF. CLSM showed that the dead-to-live ratios of biofilms treated with SCF, SDF, and water were 0.77 ± 0.16, 0.88 ± 0.40, and 0.44 ± 0.03, respectively (pWater). The Log CFU values of the biofilm treated with SCF, SDF and water were 6.7±0.1, 6.6±0.2 and 7.8±0.1 (p