We do not use fluoride in any form (if we can help it, though I know it is many canned/bottled foods and beverages, but we don't consume many of those).
I buy water for 30 cents a gallon from a WaterWindmill, which uses a 7 stage purification process including reverse osmosis (which, along with distillation, is the only method I know which removes fluoride.) I would no more drink the tap water here than I would drink the sewer water, jmho! Not only because of the fluroride, but the chlorine, the benzine, the arsenic, the you name it. I have seen the local water reports, and I could care less about "safe levels" of such poisons in my water! I don't want ANY levels if I can avoid it.
Rarely, I cook with the tap water, such as to steam veggies, but if I am making soup or something which involves water directly added to the food and consumed, filtered.
Of course, lacking a filter on the showerhead, we probably absorb a lot of stuff anyway, sigh.
My kids have had some tooth decay, but very little compared to what I had as a kid (while drinking and using fluoride pastes).
Every cavity either has had was teeny-tiny, of a size which probably would have remineralized on its own. But I did not/do not consider myself knowlegable enough about that to forego having them filled (with non-mercury fillings, of course!)
My son was 7 when he first saw a dentist, for a very tiny cavity on a back molar which I "diagnosed".
His diet played a large part in that, I'm sure; vegetarian (vegan for several years) and extended breastfeeding (till 4 or so)
A few years later, he had several other very tiny-only showed up under the special light with the dye cavities filled. I really think that if we had remained as careful with our diet as he grew older, he would not even have had those, but we got more relaxed and allowed some less decent stuff to creep in

My DD has likewise been raised on a veggie diet and extended BF (she is turning 6 next mth and STILL takes a nip before bed if I let her, lol!)
She's had maybe 3-4 teeny-tinies. (consuming our still way better than typical but currently less than ideal diet)
Both have been cavity free for 2 yrs of checkups now.
Last ortho visit, they were cleaning my son's teeth, and he told them he didn't use fluoride/refused the treatment. The assistant who spoke with me afterwards looked at me as if I had 3 heads when I confirmed this, lol!
My view remains that even IF ingested and/or topical fluoride strengthens teeth and prevents decay, (which I do not accept, after looking carefully at the data; I think many studies have been faulty for one reason or another and that, overall, fluoride weakens the teeth and the rest of the skeletal system, as well as damaging the reproductive and immune system, to name two, JMO) the toxicity on the rest of the body and in general is unacceptable. Rat poison might prevent tooth decay, too, but forget it! JMHO. A few fillings is a small price to pay for avoiding the negative effects of fluoride.
Lilith, mom to John, 13 and Sage, 5
BTW, a recent story I saw might be of interest to some on this topic:
http://www.chron.com/cs/CDA/ssistory.mpl/health/3266195
"July 14, 2005, 10:41AM
Harvard probing professor's fluoride report...Harvard University said it is investigating whether a dentistry professor who edits a newsletter funded by a toothpaste maker played down research showing an increased cancer risk from drinking fluoridated tap water.
The school will work with the National Institute of Environmental Health Sciences to review Chester Douglass' research into fluoride exposure and osteosarcoma, a rare form of bone cancer, Harvard Medical School spokesman John Lacey said.
The institute awarded a $1.3 million study grant in 1992 to Douglass, who found that the odds of having osteosarcoma after drinking fluoridated water were "not statistically different" from the odds for who drank non-fluoridated water.
Elise Bassin, a doctoral student supervised by Douglass who studied some of the same people, reported in her 2001 thesis that boys who drink fluoridated water appear to have an increased risk of developing the bone cancer...."Among males, exposure to fluoride at or above the target level was associated with an increased risk of developing osteosarcoma," Bassin wrote. "The association was most apparent between ages 5-10 with a peak at 6 to 8 years of age."
Douglass' study looked at men and woman of all different ages who drank fluoridated tap water. Bassin looked at the boys and girls used in Douglass' study and verified fluoride levels in tap water for each year of the child's life.
"She found the strongest association ever between fluoridated tap water and bone cancer among boys," Wiles said."