Saliva plays key role in caries prevention

In the fight against dental caries, we commonly utilize exogenous materials such as fluoride or sealants. However, a recent study has found that a key tool for fighting caries-causing bacteria may be our own saliva.

The study, published in  Applied and Environmental Microbiology, examined salivary mucins and Streptococcus mutans, a cariogenic bacterium that sticks to teeth with adhesive polymers and forms a bacterial biofilm. This biofilm provides a protective haven on the tooth for the bacteria and its organic acid byproducts, leading to the creation of caries. The study’s authors found that salivary mucins, previously believed to do little beyond keeping saliva mucas slippery, actually play a role in defending against bacterium like S. mutans, by keeping it suspended in a liquid medium, reducing its ability to form the bacteria-welcoming biofilms.

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While the salivary mucins did not alter the growth of S. mutans, or kill the bacteria, it limited biofilm formation through the liquid suspension. This is particularly significant for S. mutans and similar bacteria that only cause cavities when they are in a biofilm on a tooth’s surface.

The study stemmed from previous work examining mucins that had protective effects against common lung pathogens. Defects in mucin production have been linked to diseases such as asthma, ulcerative colitis and cystic fibrosis. The study’s first author, Erica Shapiro Frenkel, of Harvard University, believes that this research proves that mucins aren’t just part of mucus for structure, but rather also play an active role in pathogen protection. 

The study, "Salivary mucins protect surfaces from colonization by cariogenic bacteria,"  was published in Applied and Environmental Microbiology, a publication of the American Society for Microbiology.

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