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Patterns and rates of growth of microcosm dental plaque biofilms
C H Sissons1, L Wong, T W Cutress
1Dental Research Unit HRC, Wellington, New Zealand.
Abstract:
Rates of growth in wet weight and changes in them over time were established for microcosm dental plaques cultured from the mixed salivary bacteria in an artificial mouth. Standardized conditions included a continuous supply of medium containing 0.25% mucin and 1.5 ml of 5% w/v sucrose in 6 min every 8 h. Plaques were weighed daily. Plaque wet weight and total protein were highly correlated. Plaque doubling times were 3-7 h over day 1 and 9-21 h over day 2, which is similar to in vivo plaques. Subsequently, growth curves were either linear or between a linear and exponential increase. Evidence was obtained for plaque blooms. Methyl paraben (0.2%) applied for 15 min (3.75 ml) 6 times daily inhibited growth but only for 3 days, after which the rate was similar to control plaques, indicating that selection for resistance had occurred. It was concluded that the regulation of plaque growth rates is complex and does not conform to simple growth pattern models. Detailed studies of plaque growth and the effects of antiplaque agents can be carried out using this experimental system.
Insights
Dental plaque growth in an artificial mouth system mimics in vivo conditions, showing complex regulation and potential resistance to antimicrobial agents like methyl paraben.
Area of Science:
- Microbiology
- Biotechnology
- Oral Health
Background:
- Dental plaque formation is a complex process influenced by bacterial growth and environmental factors.
- Understanding plaque dynamics is crucial for developing effective oral hygiene strategies and antimicrobial treatments.
Purpose of the Study:
- To establish and characterize growth rates of dental plaque in a controlled microcosm system.
- To investigate the effects of a common antimicrobial agent on plaque growth dynamics.
Main Methods:
- Culturing mixed salivary bacteria in an artificial mouth system with a continuous supply of mucin and sucrose.
- Daily weighing of plaque wet weight and correlation with total protein content.
- Monitoring plaque doubling times and growth curve patterns over multiple days.
Main Results:
- Plaque wet weight and total protein showed a high correlation.
- Plaque doubling times ranged from 3-7 hours on day 1 and 9-21 hours on day 2, comparable to in vivo rates.
- Methyl paraben initially inhibited growth but resistance developed within 3 days, leading to growth rates similar to controls.
Conclusions:
- The artificial mouth system effectively models dental plaque growth, exhibiting complex regulatory patterns.
- Dental plaque can develop resistance to antimicrobial agents, highlighting the need for multifaceted antiplaque strategies.
- This experimental system provides a valuable tool for detailed studies on plaque development and the efficacy of antiplaque agents.