Department : Public Health Dentistry
Keyes' Modified Model of Dental Caries, also known as the "Ecological Plaque Hypothesis," is a dental theory developed by Dr. John J. Keyes in the 1960s. This model provides insights into the development and progression of dental caries (tooth decay) based on the interplay between dental plaque and the host's oral environment. Here are the key components of Keyes' Modified Model:
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Dental Plaque: Plaque is a biofilm that forms on the tooth surface, consisting of bacteria and their metabolic products. |
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According to Keyes, dental caries begins when specific acidogenic (acid-producing) bacteria in dental plaque accumulate and ferment dietary carbohydrates, leading to the production of acid. |
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Acid Production: Acid-producing bacteria, particularly Streptococcus mutans and Lactobacillus species, metabolise sugars and produce acids, primarily lactic acid, which lowers the pH in the oral environment. |
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Critical pH: Keyes proposed that there is a critical pH level (around 5.5) at which enamel demineralisation begins. When the pH drops below this threshold, minerals (calcium and phosphate) start to dissolve from the tooth enamel, causing demineralisation and ultimately leading to cavities. |
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Host Factors: Keyes emphasised that the susceptibility to dental caries is influenced by host factors, including salivary flow rate, buffering capacity of saliva, and the presence of factors like fluoride. Saliva plays a crucial role in neutralising acids and remineralising the tooth enamel. |
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Time Factor: The model considers that dental caries is a dynamic process that occurs over time. Frequent exposure to fermentable carbohydrates and prolonged periods of low pH in the mouth increase the risk of tooth decay. |
