Modified Plaque Glycolysis and Regrowth Model (PGRM-M): Understanding Antiplaque Potential

Objectives: Background/Objective: Understanding the mechanisms of periodontal diseases, their management, and the causal relationship between plaque and gingivitis is an ongoing discussion. This poster presents the potential of a Modified Plaque Glycolysis and Regrowth Model (PGRM-M), a promising model to monitor bacterial activity after treatment with tested products.
Methods: Methods: The PGRM-M is utilized based on the model developed by White et al. (1995) with modifications, as an ex-vivo model. Plaque samples are collected, and precise in-vitro measures are used. After obtaining IRB approval, plaque samples are collected from three donors who are healthy, free of periodontal diseases, and not taking medications at the time of collection. Donors refrain from food, drinks, and oral hygiene measures overnight. Plaque is collected by swabbing a cotton-tipped applicator on each quadrant (4 swabs/donor). Each applicator is suspended in 0.03% Tryptic Soy Broth (TSB), and vortexed for 20 seconds. Pooled plaque is incubated overnight in 40% TSB, supplemented with 10% sucrose. Overnight samples are supplemented with 40% sucrose, then subjected to 50 μL of corresponding treatments. De-ionized water (di-H2O) and Cetylpyridinium chloride (CPC) are used as negative and positive controls, respectively. Both metabolic and regrowth activity (pH levels; OD at 600_nm, normalized for biomass) are measured at baseline and hourly for four hours.
Results: Results: Continued decrease in metabolic activity and continued growth of the biofilm were observed in (di-H2O). The opposite was found with (CPC): stable pH level over time and inhibition of plaque regrowth. Both parameters are measured in tested treatments. Findings for each treatment are compared to baseline and to positive and negative controls.
Conclusions: Conclusion: The PGRM is a valid method, recommended in the FDA’s 2003 Proposed Rules for antiplaque/antigingivitis over-the-counter drug products.. Our modified, ex-vivo model provides precise measures for a better understanding of the antiplaque potential of products, a factor documented to cause gingivitis.