Tools against dental plaque: toothbrush, floss, and bacteria?

Beneficial bacteria living on our tongues and cheeks can actually help fight the buildup of plaque. Toothpaste might one day harness our body’s own tools against tooth decay.

More than 700 species of bacteria thrive in the hot, moist conditions of our mouths. Streptococcus mutans, for one, clings to the teeth, coating them as an organized community called biofilm. As S. mutans digests sugars, it produces acids that eat into our enamel and cause cavities, ScienceNOW explains.

Since 2009, scientists have known that the friendly bacterium Streptococcus salivarius can stop bacteria associated with tooth decay from forming those thin biofilm layers – or plaque.

Now, researchers led by Hidenobu Senpuku of the National Institute of Infectious Diseases in Tokyo have figured out what’s behind S. salivarius’s plaque-fighting superpowers.

1. First, they separated out the proteins found in the friendly bacteria.
2. Then they mixed each kind of protein with S. mutans cells and measured which cultures grew the smallest amount of biofilm.

• They found that the enzyme FruA – which breaks apart complex sugars – is the most capable biofilm blocker.

When people eat starchy or sugary foods containing fructose, like fruit or soda, S. salivarius makes a lot of sugar-cleaving FruA, which then chops up the sugars into more easily digestible ones. But in doing so, S. salivarius robs the plaque-forming bacteria of what they need for forming biofilms, ScienceNews explains.

So how about that candy binge? Well, when researchers increased the concentration of sucrose, the beneficial bacterium lost its ability to prevent biofilm formation. They’ve still got to work on finding that perfect formulation.

However, the researchers did show that another form of FruA – produced by a common fungus and available off-the-shelf – also stymies plaque equally well. That might speed the development of toothpastes that include FruA, says Senpuku.

The study [pdf] was published in Applied and Environmental Microbiology.

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