| Dental plaque is a multi-species biofilm that, left untreated, can produce diseases including caries, gingivitis, and periodontitis. A model system for simulating dental plaque biofilms was developed and used for evaluating antiplaque agents and formulations.; A simulated dental biofilm was attempted by constructing a multi-species inoculum of common oral microorganisms that included streptococci, fusobacteria, and actinomycetes. The biofilm was grown in Phytone Peptone Yeast Extract medium (PPY) which were supplemented with various concentrations of sucrose and/or saliva. Because of streptococcal competition, the biofilms that were produced using this model became mono-species instead of multi-species.; This monospecies model was used to evaluate commercially available antiplaque mouth rinses that contained chlorhexidine or botanical essential oils. A combination of spectrophotometry and the use of selective general growth media were used to evaluate the viability, growth and survival of the biofilms.{09}A 30-second exposure to the essential oil-containing mouth rinse reduced the population of a 48-hour biofilm by approximately 75%. The population of the biofilm treated with the essential oil containing formulation subsequently doubled within 24 hours to the same level of viable organisms found in the untreated biofilm. By comparison, the population of a 48-hour biofilm treated with 0.12% chlorhexidine showed the same level of viable organisms as the untreated biofilm; however, the population and biomass of the chlorhexidine treated biofilm did not increase or decrease for an additional 72 hours. This indicated that in this model chlorhexidine was bacteriostatic and not bactericidal. The extended duration of the antimicrobial activity of chlorhexidine, in situ, indicated that chlorhexidine was substantive.; Therefore, this model, although single species, provided an easily accessible means for evaluating antimicrobial compounds and formulations against dental plaque and can also simultaneously distinguish between substantive agents and non-substantive agents. |
