Fluoride Ion and Dental Health

Fluoride ion tends to replace the isoelectronic ion OH in solids. In particular, hydroxyapatite, Ca5(P04)30H, the chief constituent of tooth enamel, reacts slowly with aqueous fluoride to form fluoroapatite, which is harder and more resistant to tooth decay. The dental profession therefore advocates fluoride treatments at the time of regular dental checkups, and also (primarily to provide for the dental health of children) the presence of 0.7-1.0 ppm natural or added F in drinking water. Too much ( 4 ppm) F in water, however, is acknowledged to cause mottling of teeth and bone sclerosis. Thus, the range of concentrations over which fluoride in public drinking water is considered to be beneficial is rather narrow. 

This much is certain there has been a dramatic decline in the incidence of dental caries since fluoridation of water supplies became widespread. This is doubly fortunate inasmuch as the safety of mercury amalgams, the 

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