German scientists say fluoride reduces the ability of decay-causing bacteria to stick to teeth so it is easier to wash away when brushing or with saliva.

Karin Jacobs and colleagues said despite a half-century of scientific research, controversy exists over exactly how fluoride compounds reduced the risk of Tooth decay.

Previous research established long ago that fluoride helps to harden the enamel coating that protects teeth from the acid produced by decay-causing bacteria. Newer studies already found that fluoride penetrates into and hardens a much thinner layer of enamel than previously believed, lending credence to other theories about how fluoride works, Jacobs said.

The study, published in the journal Langumir, described new evidence fluoride also worked by impacting the adhesion force of bacteria that stick to the teeth and produce the acid that causes cavities.

The experiments, performed on artificial teeth, revealed fluoride reduces the ability of decay-causing bacteria to stick, so that also on teeth, it is easier to wash away the bacteria by saliva, brushing and other activity, Jacobs said.

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SAARBRUCKEN, Germany, May 3 (UPI)