Comparison of Plaque Development Using Static and Dynamic In-vitro Models

The formation of plaque on dentures has significant implications for the health and satisfaction of the edentulous patient. Initially deposited by early colonizers, plaque can thicken and mature to support a variety of organisms including pathogens. Anaerobes, protected by oxygen depleted regions in plaque, have been implicated in the generation of denture-related malodor. Additionally, the incorporation of tannins and other dietary chromophores into plaque can result in the unsightly discoloration of the denture.

In order to assess the efficacy of denture cleansing formulations, a variety of in-vitro models have been developed and validated, most of which utilize plaque that has been grown on acrylic substrates. In the simplest of models, plaque forms while a nutrient broth remains relatively static. Objectives: In this study, we examine the utility of introducing continuous flow of a growth medium during plaque development.

Methods: Slides made of industrial acrylic resin were cleaned and sterilized before exposure to a nutrient solution consisting of Todd Hewitt broth, saccharose, and pooled human saliva. Plaque was developed during incubation for up to 18 hours at 37º C. One set of slides was prepared without agitation of the solution while another set was incubated on a shaker table set to oscillate at 40 rpm. After incubation, slides were removed from the broth and allowed to air dry. Plaque development was assessed qualitatively by inspection and quantitatively by reflectometer.

Results: Resulting biofilm formation was significantly affected by the introduction of agitation of the solution. Although fluid flow was able to transport nutrients (and carry away wastes) more efficiently, shear forces applied to the biofilm resulted in reductions in quantity of plaque generated. Conclusion: Fluid flow (representing salivary flow) has the potential to influence plaque formation and should be considered for model development.

Disclosure: Research supported by GlaxoSmithKline