A new study has found that the protective shield fluoride forms on teeth is up to 100 times thinner than previously believed. This raises questions about how this renowned cavity-fighter really works.
It has long been believed that fluoride changes the main mineral in tooth enamel, hydroxyapatite, into a more-decay resistant material called fluorapatite. But the new research found that the fluorapatite layer formed in this way is only 6 nanometers thick -- meaning it would take almost 10,000 such layers to span the width of a human hair. According to Science Daily:
"The scientists question whether a layer so thin, which is quickly worn away by ordinary chewing, really can shield teeth from decay".
Another new study shows that exposure to fluoride may lower children's intelligence. In addition to toothpaste, fluoride is added to 70 percent of U.S. public drinking water supplies. PR Newswire reports:
"About 28 percent of the children in the low-fluoride area scored as bright, normal or higher intelligence compared to only 8 percent in the 'high' fluoride area ... in the high-fluoride city, 15 percent had scores indicating mental retardation and only 6 percent in the low-fluoride city."