Modelling oral malodour in a longitudinal study

The aim of this study was to develop an in vitro model of the tongue microflora in order to assess anti-malodour compounds before clinical evaluation. Biofilms, derived from the tongue microflora, were grown in a constant depth film fermentor (CDFF) with nutrients supplied in the form of mucin- and serum-containing artificial saliva. Differential agars and a halimeter were used to determine the bacterial microflora and production of volatile sulphur compounds (VSCs), respectively. The resulting biofilms had a bacterial population which contained, on average, 29% streptococci, 48% Gram-negative anaerobes and 2.5% with an H2S-producing phenotype. When the biofilms were pulsed with either chlorhexidine or zinc acetate there was a reduction in the number of H2S-producing bacteria, however these counts subsequently recovered as pulsing continued. The generation of VSCs was correlated to the viable counts of the H2S-producing bacteria. By pulsing with anti-malodour compounds over time we observed a reduction in the quantity of VSCs produced and a change in the composition of the plaque to one which contained fewer H2S-producing bacteria.