Essay by ooboo May 2003

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In the past, cavities used to be the usual and frequent cause of a toothache or the loss of a tooth. Now cavities are the dreaded holes in your mouth that are frightening and alarming to have. However, over the past few decades, tooth decay has been reduced dramatically. The key reason is fluoride. Despite an almost exponential increase in dental power and research information, the use of fluorides in dentistry is probably the most important single factor to explain the significant decrease in dental caries seen in most countries. As a result, a flood of new fluoride products and information are now available.

The fluoride ion comes from the element fluorine, which is the 13th most abundant element in the earth's crust. Although it is never encountered in its free state in nature, it does exist only in combination with other elements as a fluoride compound, usually metal.

Fluorine is a pale-yellow, highly corrosive, poisonous gaseous element. It is the most electronegative and reactive of all elements. It combines violently with everything that it comes in contact with, and its acids are very destructive; even a small amount can be lethally poisonous. The salts of these acids are considered some of the most toxic substances on Earth and are frequently used as poisons and insecticides.

Fluoride enters the atmosphere by volcanic action and by the transport of soil and water particles. It is returned to the earth's surface by deposition as dust, rain, snow, and fog. Fluoride enters the hydrosphere by leaking from soils and minerals into ground water and by entry with surface waters. Fluoride enters vegetation by uptake from soil and water, by absorption from the air, and by deposition from the atmosphere and from rain splash. It returns to the soil through plant wastes, or...