Anti-odour effects of toothpaste formulations using in-vitro flat-bed biofilm model

Objectives: A modified flat-bed perfusion biofilm matrix system was tested using active toothpaste formulations directly without dilution, as a layer in direct contact with the biofilm matrix surface. Final biofilm yields and VSC biogenesis were measured to show the relative efficacy of toothpaste formulations. Methods: Diffusion characteristics of the flat-bed system to active treatment with meridol® HALITOSIS tooth & tongue gel (TTG; 1400 ppm F^- from amine fluoride/stannous fluoride, 0.5% zinc lactate, oral malodour counteractives) was assessed using a bioluminescent target species coupled with a low light photon camera to visualise the kill kinetics. Three biofilms received 5, 15 and 30-min treatment with TTG respectively to determine the optimum time of exposure. VSC biogenesis was measured from headspace by OralChroma prior to and following treatment of 2 daily applications for 4-days of treatment and controls (placebo, 1% chlorhexidine gel and sham treatment). Viable counts were performed at the end of experiments by destructive sampling and plating on selective and non-selective agar. Results: Following treatment with TTG, the biofilm with lux target gave >50% reduction before recovering to a steady-state over 10 h suggesting that the treatment mechanism was bacteriostatic inhibition. For 15 and 30-min treatment exposure, almost identical reductions in final biofilm yields were seen. Biofilms treated with TTG gave greatest reductions in both pre-post levels of H₂S (P<0.01) and CH₃SH (P<0.05) and population yields at the end of the experiments (p<0.001). Conclusion: The in vitro flat-bed perfusion model may be used to replicate many of the activities and reactions believed to be occurring by the tongue biofilm microflora within a real mouth, including VSC biogenesis and their inhibition by exposure to active agents as components of toothpastes and gels applied in direct contact with the biofilm. Supported by GABA International AG.