A commercial SnF toothpaste formulation reduces simulated human plaque biofilm in a dynamic typodont model

Aims: We present a dynamic typodont biofilm model (DTBM) incorporating (1) human dentition anatomy, (2) fluid flow over intermittently fluid bathed tooth surfaces and (3) an oxic headspace to allow aerobic and anaerobic niches to develop naturally, as a screening tool to assess the effect of stannous fluoride (SnF) toothpaste against a simulated human plaque biofilm (SPB). Methods and results: First, hydroxyapatite (HA) coupons were inoculated with human saliva/plaque and cultured at 37°C under air. Selected species representative of common commensal and anaerobic pathogens were quantified for relative abundance changes over 4 days by PCR densitometry to confirm the culture conditions allowed the proliferation of these species. A continuous culture DTBM reactor on a rocker table was inoculated with saliva/plaque and incubated at 37°C for 24 h. Tooth shear stress was estimated by particle tracking. A SnF toothpaste solution, or a sham rise was administered twice daily for 3 days to mimic routine oral hygiene. SPB biomass was assessed by total bacterial DNA and methylene blue (MB) staining. Early colonizer aerobes and late colonizer anaerobes species were detected in the HA and DTBM, and the trends in changing abundance were consistent with those seen clinically. Conclusions: Treatment with the SnF solution showed significant reductions of 53.05% and 54.4% in the SPB by MB staining and DNA, respectively. Significance and impact of study: The model has potential for assessing dentition anatomy and fluid flow on the efficacy of antimicrobial efficacy against localized SPB and may be amenable to the plaque index clinical evaluation.