Fluoride is in all sorts of oral care products, from tooth paste to mouthwash and even in most municipal water supplies. But how does it really work?

Research from the beginning of the latter half of the 20th century implicated fluoride in re-mineralizing the enamel layer of the tooth, thereby making it stronger and more resistant to decay from bacteria-releasing acids that cause caries and cavities.

Recent research has indicated that fluoride doesn't penetrate as deep into teeth as researchers have thought for decades, which left scientists wondering how the chemical protects teeth from decay.

New research from one German university, coming out of both a microbiology institute and the experimental physics department from Saarland University, show that fluoride may hinder the ability of bacteria to adhere to teeth.

Everyone knows of the pesky film that develops on teeth in between brushings. This layer of plaque includes millions of bacteria and their byproducts. The bacteria of the mouth are known to stick to teeth and produce acids, weakening teeth and causing cavities. The researchers used artificial teeth to show fluoride presence inhibited the ability of bacteria to stick to the outer layers and allowed them to be washed away easier by brushing or even spitting.

The researchers tested the theory using three types of bacteria, Streptococcus mutans, Streptococcus oralis, and Staphylococcus carnosus, all known to cause tooth decay.

"What is interesting, in any case, is that fluoride appears to weaken bacterial adhesion forces in general," explained the physics collaborators on the study.

Fluoride is hailed as a miracle in promoting healthy oral hygiene in the middle of last century and allowing millions of people around the world to have fewer cavities and oral surgeries as a result of its healthy benefits.

The research published in the journal Langmuir can be found here.