Chemostat Flow Cell System: An in vitro Model for the Evaluation of Antiplaque Agents

Abstract

We developed an experimental in vitro model of dental plaque to assess the potential efficacy of antiplaque agents. The model used a chemostat, which provided a continuous source of 5 species of oral bacteria grown in an artificial "saliva-like" medium. This mixture was pumped through six flow cells, each containing two types of surfaces on which plaque formed and was subsequently measured. Formation of bacterial plaque on hydroxyapatite surfaces was assessed by measurement of the DNA and protein content of the plaque film. The amount of bacterial plaque formed on germanium surfaces was measured by attenuated total reflectance (ATR/FT-IR) spectroscopy. Plaque viability was also assessed by a fluorescent staining technique. The quantity of plaque formed on both types of surfaces gradually increased with the duration of flow (from 24 to 72 h) through the cells during a 72-hour experimental period. The flow cells were then pulsed with experimental treatment solutions for 30 s, twice daily. Parallel to results of human clinical studies, the model was capable of discriminating among water, a placebo mouthrinse, and an active antimicrobial mouthrinse formulation containing 0.03% triclosan. It therefore offers a valuable alternative to animal model testing and allows for more rapid evaluations under well-controlled experimental conditions.

Antimicrobial Penetration and Efficacy in an In Vitro Oral Biofilm Model

“…These studies often use plate counts to enumerate viable cells and calculate antimicrobial efficacy (2,4,11,15,19,20,28,29,36,40), although some analyses have been performed based on fluorescence or luminescence assays (7,16,19). Very few studies have addressed the issue of active penetration into dental plaque or oral biofilm (14,18,34,38).…”

“…Very few studies have addressed the issue of active penetration into dental plaque or oral biofilm (14,18,34,38). There are also few studies that reported measurements of oral biofilm removal by chemical treatments (7,41).…”

The Role of Sucrose in the Development of Oral Biofilm in a Simulated Mouth System

“…The sterile saliva used in the study was obtained from a single volunteer to minimize the variations that may arise. Although biofilms can be grown on various type of substratum [24][25][26][27][28] , glass beads were chosen because of its transparency features which make it easier to use in the system, as well as facilitate evaluation of samples. In addition, it has been reported by Pratt-Terpstra et al [29] that glass surfaces and enamel behave similarly with regard to oral microbial adhesion properties.…”

Adverse Influences of Antimicrobial Strategy against Mature Oral Biofilm

“…In contrast, there are some reports that the biofilm structure has been successfully degraded by repeated exposures of mouthrinse [23][24][25]. Although it is likely that biofilm reduction may be enhanced by repeated pulse of a mouthrinse, this approach may not always be effective.…”