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20130523-Fluoride_Loosens_Bacterial_Enamel_Grip_r2This is Scientific American's 60-Second Health. I'm Karen Hopkin. Got a minute?

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Fluoride helps fight cavities.

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That's why it's in our drinking water and toothpaste.

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But how this mineral works its dental magic is still somewhat mysterious.

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Now, researchers offer an incisive solution.

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They find that fluoride treatment can loosen bacteria's grip on tooth enamel.

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The study is in the journal Langmuir.

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Scientists used to think that fluoride could harden tooth enamel, helping it retain the minerals that protect teeth from the acid produced by our oral flora.

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But recent work has shown that fluoride doesn't really penetrate past the tooth's thinnest outer layer, suggesting that something other than hardening is going on.

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To drill deeper into this toothsome mystery, researchers whipped up a set of artificial choppers, made of the same stuff as teeth.

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And they used atomic force microscopy to take a closer look at how bacteria interact with this dental material.

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They found that three different strains of cavity-causing bugs cling less tightly to enamel that's been rinsed with fluoride.

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The bacteria carry a net negative charge on their surfaces.

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So the negatively charged fluoride ions in the treated enamel may be literally repulsive to the bacteria.

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Which causes them to bite the dust.

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Thanks for the minute, for Scientific American's 60-Second Health. I'm Karen Hopkin.

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