It has been show that the addition of fluoride to water has had no effect on the prevention of cavities, as claimed by those who have pushed and continue to push to have fluoride added to our drinking water. On the other hand, it was been contributed to varies health risk effecting the: reproductive system, brain, bones, joints, puberty, IQ.
Here is a chart that shows a number of countries side by side, showing that countries that do not add fluoride to their water have the same, if not better improvement in overall dental health among the general the population; http://i.imgur.com/IZiUCWP.gif
Furthermore, there is research that has shown that adding fluoride to drinking water is completely unnecessary, since the public is already expose to high levels of fluoride, through varies means