Because numbers of communities have one or more parts per million of fluorine occurring naturally in their water, it led to the feeling that it would be logical to put all water supplies on an equal basis. However, the process used is not the same. The fluorine that is found naturally occurring in water is usually calcium fluoride while that added artificially is sodium fluoride. Chemists claim there is no difference, that it is the fluorine ion that is important. However, other scientists feel there is a synergistic activity between compounds that exist in the natural state.
Most proponents also say that fluorine makes the tooth harder.
Any dentist who has taken care of cavities in people from high fluorine areas, as I did in Texas during the war, know that they are much easier to cut with the dental drill. The mottling disfigurement of the teeth that occurs in one out of ten is something the victims abhor and would give anything to correct. When the teeth of fluorine-treated individuals are examined chemically, they are found to be composed of calcium fluoride instead of their usual calcium carbonate composition. A tooth composed of calcium fluoride, even though softer, doesn't decay us readily because calcium fluoride is less soluble to acids than is calcium carbonate. Decay takes place in an acid environment created by sweets and refined carbohydrates.