The story of fluorine in relation to the teeth is a fascinating example of controlled research and bears brief retelling. Back in the 1890's the dentists in Colorado began to observe that children and adults who had lived in the area of Colorado Springs for the first eight years of their lives had a strange kind of enamel on their teeth. It was mottled enamel, pocked with little brown or chalky-white patches.
Later this mottled enamel began turning up in other communities. Eventually it was traced to the drinking water of the community. About 1931, the specific element in the water which caused the mottled enamel was discovered. It was fluorine Of course; this gaseous element appears in chemical composition as fluoride.
Then, in the 1930's the dentists began to make a careful study of the people with mottled enamel. Contrary to previous assumption, it turned out that these people had about 60% fewer cavities than people who were brought up in areas where there were no fluorides in the water supply. In other words, the fluorides helped to protect teeth from decay.
The U.S. Public Health Service, whose dental division has conducted much of the fluoride research, then set out to determine how much fluorine added to the drinking water would cut down the caries rate and still not produce mottled enamel. The answer came out about one part per million. This amount is perfectly safe and does not mottle the teeth.
On the basis of this research some ten cities in the United States and Canada began the mass public health experiment of adding fluoride (one part per million) to their drinking water. This is called fluoridation. The results were so convincing that hundreds of communities have now added fluorides to their municipal water supplies, but not, it may be said, without public objection in many places.
Campaigns for fluoridation of public drinking water supplies as a strong line of defense against dental caries were pioneered by the U.S. Public Health Service and have been approved by virtually all important public health agencies. Nevertheless there are still many "crackpot" and a few responsible voices raised against it.