Scientists identify several new bacteria that cause dental caries

oral bacteria
Photo: otnaydur – 123rf

The technique called next-generation DNA sequencing allows for very accurate identification of the trillions of microbes in the human body. For several diseases, knowing which microbes densely populate the organ/tissue in question or become absent from it during disease can help develop effective treatments. 

Certainly this is the case for tooth decay in which acid-producing bacteria eat away at the out layer of teeth and cause cavities.

A type of bacteria called the mutans streptococci are the most commonly implicated microbes in dental caries. Their increase causes dental decay. But, could other microbes be responsible as well?

Scientists globally have looked into this question. However, focus on the younger demographic has been low. Meanwhile, in Japan, the number of young adults developing dental caries is increasing.

Spurred by this increase, a team of researchers from Japan, led by Dr Uchida-Fukuhara from Okayama University, called for Japanese university student volunteers for oral examinations.

The students answered a survey about their dental health at the beginning of the study and during a follow-up after three years. This told the researchers which students had significantly increased dental caries after this time and who didn’t. The researchers grouped the students during the follow-up. They then collected saliva samples of randomly selected students from these groups, which they analysed via next-generation DNA sequencing to obtain microbial profiles.

It turned out that very similar oral microbial diversities existed in both groups. But in Group A, the abundances of the bacterial families Prevotellaceae and Veillonellaceae, and genera Alloprevotella and Dialister, were greater than those in Group B. These two families are known to comprise species that produce acid as well. 

This finding, therefore, suggests new prevention possibilities for dental caries that does not focus on keeping mutans streptococci populations in check.

Interestingly, both groups had low levels of mutans streptococci. Should the focus of research on what causes dental caries change?

The results of the study, published in the International Journal of Environmental Research and Public Health, underscore the necessity of updating current knowledge on the oral microbial community and its role in the development of dental caries. 

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