Anti-odor Effects of Mouthrinse Formulations Using in vitro Biofilm Model

Objectives: A modified in vitro matrix biofilm perfusion model was used to study tongue-derived microcosms using a novel electrode assembly based on microbial fuel cell technology. In addition to the model modifications, a further aim of this study was to demonstrate the biofilm responses following exposure to biocidal, biostatic or volatile sulphur compound (VSC)-inhibiting active compounds. Methods: The existing model was modified to give real-time measurements expressed as electrode power output, which were proportional to H₂S level. H₂S biogenesis was also measured by SIFT-MS, along with other volatile organic compounds (VOCs). Tongue-derived biofilms were pulsed with experimental mouthrinse (1400 ppm F^- from amine fluoride/stannous fluoride, 0.2% zinc lactate, oral malodour counteractives), placebo and controls including Zn²⁺ ions and chlorhexidine. Changes in viable count of perfusate were followed prior and following treatment. Viable counts were also performed at the end of the experiment by destructive sampling. Results: Compared with their pre-treatment conditions, all biofilms responded to the treatments in terms of reductions in hydrogen sulphide generation (as detected by the biofilm-electrode response) (P<0.05) and other microbial VOCs (as detected using SIFT-MS) (P<0.01). By comparison, microbiological analysis of the treated and control biofilms show that formulations with active agents gave reduced cell populations compared to the control biofilm (P<0.05). The experimental mouthrinse showed a marked reduction in final biofilm yield compared to placebo (P<0.0007) and was markedly better at reducing VSCs (P<0.05). Conclusion: This in vitro 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 H₂S and VOC biogenesis and their inhibition by exposure to active agents. Supported by GABA International AG.