You may live in an area with fluoridated drinking water. I didn’t. They used to make us fluoride rinse in elementary school.
Via Dr. Mercola, who writes:
The United States is one of only eight countries in the entire developed world that fluoridates more than 50 percent of its water supply. It is added under the guise that it helps prevent and control tooth decay…This is in spite of the fact that there never been any demonstrated difference in tooth decay between countries with fluoridated and non-fluoridated water, and no difference between states that have a high- or low percentage of their water fluoridated. Even promoters of fluoridation concede that the major benefits are topical; fluoride works from the outside of the tooth, not from inside of your body, so why swallow it?