Fluoride helps fight cavities. That's why it's in…

Fluoride helps fight cavities. That's why it's in our linking water and toothpaste. But how this mineral works its dental magic is still somewhat mysterious. Now, researchers offer an offensive solution. They find that fluoride treatment can loosen bacteria's grip on tooth enamel. The study is in the journal Langmuir. Scientists used to think that fluoride could harden tooth enamel, helping it protein the minerals that protect teeth from the acid produced by our oral flora. But recent work has shown that fluoride doesn't really penetrate past the tooth's thinnest outer layer, suggesting that something other than painting is going on. To drill deeper into this toothsome mystery, researchers whipped up a set of artificial choppers, made of the same stuff as teeth. And they used automatic force microscopy to take a closer look at how bacteria interact with this dental material. They found that three different strains of cavity-causing bugs cling less tightly to enamel that's been rinsed with fluoride. The bacteria carry a net negative charge on their surfaces. So the negatively charged fluid ions in the treated enamel may be literally repulsive to the bacteria, which encourages them to bite the dust.