Re: How does flouride affect teeth?

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.