Validation of an in vitro biofilm model of supragingival plaque

The study of biofilm structure and function mandates the use of model syste ms for which a host of environmental variables can be rigorously controlled . We describe a model of supragingival plaque containing Actinomyces naeslu ndii, Veillonella dispar, Fusobacterium nucleatum, Streptococcus sobrinus, and Streptococcus oralis wherein cells are cultivated anaerobically in a sa liva-based medium on hydroxyapatite discs coated with a salivary pellicle, with material and pieces of apparatus common to all microbiology laboratori es. After 0.5 hr, 16.5 hrs, 40.5 hrs, and 64.5 hrs, the composition of adhe rent biofilms was analyzed by culture techniques, live/dead fluorescence st aining, and confocal laser scanning microscopy. Repeated independent trials demonstrated the repeatability of biofilm formation after 40.5 hrs and 64. 5 hrs. Brief exposures of biofilms to chlorhexidine or Triclosan produced l osses in viability similar to those observed in vivo. This biofilm model sh ould prove very useful for pre-clinical testing of prospective anti-plaque agents at clinically relevant concentrations.