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What are the new paradigms in diet and the microbial aetiology of dental caries?


This summary is based on the article published in the International Dental Journal: Diet and the microbial aetiology of dental caries: new paradigms (December 2013)

David J. Bradshaw and Richard J. M. Lynch


Courtesy of Wiley Publishing: You can access the full-text article for the next 3 months. 

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The microbial and dietary factors that drive caries have been studied scientifically for 120 years. Frequent and/or excessive sugar (especially sucrose) consumption has been ascribed a central role in caries causation, while Streptococcus mutans appeared to play the key role in metabolising sucrose to produce lactic acid, which can demineralise enamel. 

Many authors described caries as a transmissible infectious disease. However, more recent data have shifted these paradigms. Streptococcus mutans does not fulfil Koch’s postulates – presence of the organism leading to disease, and absence of the organism precluding disease. Furthermore, molecular microbiological methods have shown that, even with a sugar-rich diet, a much broader spectrum of acidogenic microbes is found in dental plaque.

While simple sugars can be cariogenic, cooked starches are also now recognised to be a caries threat, especially because such starches, while not ‘sticky in the hand’, can be highly retentive in the mouth. Metabolism of starch particles can yield a prolonged acidic challenge, especially at retentive, caries-prone sites.

These changes in the paradigms of caries aetiology have important implications for caries control strategies. Preventing the transmission of S. mutans will likely be inadequate to prevent caries, if a sufficiently carbohydrate-rich diet continues. Similarly, restriction of sucrose intake, although welcome, would be unlikely to be a panacea for caries, especially if frequent starch intake persisted. Instead, approaches to optimise fluoride delivery, to target plaque acidogenicity or acidogenic microbes, to promote plaque alkali generation, to increase salivary flow or replace fermentable carbohydrates with non fermentable alternatives may be more promising.

Purpose of the Review

The article focuses on how a broad ‘consensus’ understanding of caries, from both a dietary and microbiological perspective, which seemed settled only a few years ago has more recently been overturned. The implications of these changes in understanding for strategies appropriate for caries control and prevention are also discussed.


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