|MadSci Network: General Biology|
Aloha, Davros, Although I teach this information in my introductory nutrition course, here at the University of Hawai`i/Manoa, I decided to read up a bit on fluoride before I answered your question. My source is Modern Nutrition in Health and Disease, 9th edition (sort of the 'bible' for us nutritionists). Fluoride, indeed, does help decrease cavities/caries in teeth. There's very strong epidemiological support for this from studies of populations at risk for dental decay. It also appears to build stronger teeth while they are forming, such as during pregnancy (for the fetus) and during childhood. Although we don't really clearly understand exactly how fluoride works to do this, Depaola (in MNHD) suggests three modes of action: 1) stronger crystals within the tooth enamel, because fluoride becomes part of the tooth structure, itself; 2) protection by being part of the saliva and keeping the teeth from losing minerals or stopping early lesions that might lead to caries; and 3) acting directly on the bacteria that are part of the process of decay (Streptococcus mutans), by interferring with their growth processes. In safe levels, either in water, in tooth pastes/powders/washes, as supplements (infants/children) or as applications by the dentist, fluoride is not toxic. Safe levels in water are from 0.7 - 1.2 parts per million...I've always just remembered about 1 ppm is safe and effective. Too much fluoride can have toxic side effects, such as fluorosis (from white flecks on the teeth all the way to brown staining, even pitting of the teeth). This can also happen on bones. At higher doses, the bones will develop a painful condition from microspicules forming on the bones, directly...that is, bone tissue where it shouldn't be. Regarding your looking on the web, it doesn't surprise me that you found incorrect information about the proper use of fluoride. There is still major opposition in certain circles to fluoridation of water and use of appropriate tooth preparations. A couple of caveats: be very careful using information from the web, in general, unless you can convince yourself that the web-site you are visiting contains legitimate, correct scientific information...look at the organization maintaining the site, the web-master (credentials?), and/or how current the information is. In addition, learn to trust the people who have little to gain from selling fluoride OR keeping others from using a safe technology. Talk to dentists, pharmacists, and your health care providers (doctor, nurse, dietitian, etc.). These people should be able to provide you with correct information, since their major concern is usually your health, first and foremost.
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