I suspect the full article Doug cited would offer an explanation of the 
causal link, and even the abstract hints at it: the poor don't get 
dental care. ( In addition, they are more exposed to junk food, for 
several reasons, such as its cheapness relative to healthier fare. 
Obesity is also rampant among the American poor.) Incidentally, in an 
interesting article on why the US  has no national health plan, Malcolm 
Gladwell in the August 29, 2005, New Yorker begins with an account 
dental problems among the poor because they can't afford regular dental 
hygiene visits.  They mostly can't afford to see dentists even when 
they have toothaches, and by not seeing hygienists, I would suppose, 
they don't get constantly lectured on the need to brush and floss. 
Gladwell points out that loss of teeth makes it still harder to eat 
healthily, thus promoting diabetes and other illnesses.

Flouridation is one of the few aspects of socialized medicine, except 
for vaccinations, that we have  in this benighted country. We should 
strive to add to it, before focussing on it as a source of suspicion, 
in my opinion.

Best,
Michael
On Aug 26, 2005, at 10:28 AM, Wren Osborn wrote:

> This is in reference to the article that Doug Brugge posted.
>
> If the low socioeconomic status families have higher incidences of 
> caries than higher socioeconomic status families and presuming they 
> are drinking fluoridated water (and I would say probably more 
> fluoridated water than higher income families because they don't buy 
> bottled water), does that mean that other factors are influencing the 
> lower incidences of caries in higher income families?  And if so 
> shouldn't that be investigated?
>
> Wren Osborn
>