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| Let’s join Prof. Masaki Kambara’s Cariology Laboratory for one day and listen to his lectures. |
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| Fluoride prevents dental caries - today, this is common knowledge. But the relationship between fluoride and teeth was discovered just about 100 years ago. It began in Colorado Springs in the USA where a local dentist became aware of the opaque or chalky white and brown color teeth on mottled teeth that were so prevalent among the inhabitants of this area. It became known that certain immigrants also had such strange teeth on their teeth. Searching for the cause of the spots, the dentist found out that it was related to the water people in Colorado Springs drank every day and the immigrants had drunk at home. However, some time had to pass before it was realized that the spots were related to the fluoride contained in the drinking water. |
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| It was a chemist that was involved in making aluminum products who discovered that the drinking water in Colorado Springs has a high concentration of fluoride when he analyzed the content of water used to clean the aluminum products. Thus, with help from an unexpected side, the relationship between teeth and fluoride in the drinking water began to take shape. At first, fluoride was considered to have a bad effect on teeth as it destroys the enamel and causes spots on the teeth. However, further studies revealed that up to a certain concentration, fluoride was found to help strengthen teeth to dental caries. This concentration was 1 ppm. In 1945, as a result of these epidemiological studies, tests were started in the USA to prevent dental caries by adjusting the fluoride concentration of the public water supply. |
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Even recently, several discoveries have been made concerning the relationship between fluoride and dental caries. One such discovery was made with shark teeth in 1990. Shark teeth regrow as many times as is necessary and are made of 100% fluorapatite (in which the OH ions of hydroxyapatite are replaced by F ions.) A scientist in Denmark thought that these teeth made of fluoride that makes teeth strong must be resistant to dental caries. To prove this hypothesis, he placed a shark tooth in the mouth to see whether dental caries would develop. The result was…: the shark tooth did get caries. The result showed that fluoride is not important as a component of teeth but because of its presence in the oral cavity. This effect is called the remineralization effect of fluoride. Using toothpaste containing fluoride when brushing the teeth, for example, is a good method of maintaining fluoride in the mouth.
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 Shark teeth were not strong enough to resist dental caries, yet they have a unique feature: sharks can grow a new set of teeth as many times as they need to. While human adult teeth have to be used for a lifetime, sharks have rows of spare teeth behind the current set of teeth. Should they lose teeth during their hunt, for example, the new set will regrow as if pushed forward on a conveyer belt. |
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