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 purported 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.
New research however, has 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 hai, leaving the scientists question;
"whether a layer so thin, which is quickly worn away by ordinary chewing, really can shield teeth from decay".
Frank Muller, Christian Zeitz, Hubert Mantz, Karl-Heinz Ehses, Flavio Soldera, Jorg Schmauch, Matthias Hannig, Stefan Hufner, Karin Jacobs. Elemental Depth Profiling of Fluoridated Hydroxyapatite: Saving Your Dentition by the Skin of Your Teeth? Langmuir, 2010; 26 (24)
Another new study shows that exposure to fluoride may lower children's intelligence.
"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."
San-Xiang Wang et al., Arsenic and Fluoride Exposure in Drinking Water: Children’s IQ and Growth in Shanyin County, Shanxi Province, China Institute for Prevention and Treatment of Endemic Disease, Linfen, Shanxi Province, People’s Republic of China.