The fluoride mystery has stumped scientists for almost 50 years. How exactly does it help stop tooth decay? Scientists may finally be onto an answer.

A recent study suggests that the fluoride mystery is actually pretty simple – the mineral reduces the ability of bacteria to stick to teeth. This makes it so that the bacteria that causes cavities and other nasty mouth problems are easily removed with brushing.

Scientists used artificial teeth to study the effects of fluoride, but stumbled upon some problems. The main issue was that tooth composition can vary wildly so the effect of fluoride can change dramatically on a tooth-by-tooth basis. Still, they found that the artificial teeth, when subjected to fluoride, repelled negatively charged bacteria by negatively charging the tooth itself.

The study is inconclusive, however, and the fluoride mystery will continue to spur controversy. The most controversial, of course, is that fluoride is added to drinking water to prevent tooth decay. Scientists say that the fluoride in water is a controlled amount that poses no risk to humans who drink it, but some people still refuse to drink fluoridated water for fear that it may pose health risks.

Regardless, much research must still be conducted before scientists can fully understand the fluoride mystery. The next step is to see if fluoride can actually weaken bacteria, thus disabling its ability to build up “fortresses” on teeth.

[h/t: LiveScience]