Public health officials say the evidence is solid that fluoridated drinking water helps protect teeth.
The federal Centers for Disease Control calls fluoridated water one of the top 10 public health achievements of the 20th century. But many people still aren't convinced.
In Florida, opponents recently persuaded Pinellas County commissioners to stop adding fluoride to the water supply — a practice the county began in 2003. By the end of the year, Pinellas will once again be the largest county in Florida without fluoridated water.
That vote came as a surprise to those who thought the question of whether to fluoridate water has long been settled. Not so, says county commissioner Norm Roche, a fluoridation opponent.
"Whenever you're dealing with the public drinking water supply ... no argument should ever be considered closed," Roche says.
Fluoridated water is endorsed by the Centers for Disease Control and Prevention, the U.S. surgeon general, the American Dental Association, and the medical establishment as a whole.
Nearly three-quarters of those on public systems have fluoridated water, according to the most recent statistics, and the number of Americans drinking fluoridated water still appears to be growing.
Dr. Ed Hopwood, chairman of the Pinellas County Dental Association's Fluoride Committee, says that 60 years of scientific research clearly detail the health benefits of fluoridation.
"There are multiple studies done on a national level showing reduction in decayed, missing and filled teeth, both in children and adults," says Hopwood, one of several dentists who spoke at the commission hearings.
But opponents note that Pinellas County isn't alone in rethinking the fluoride in its water. One group, the Fluoride Action Network, keeps a list of more than 200 communities across the U.S. that it says have dropped fluoridation in recent years.
In January, the Department of Health and Human Services proposed a new, lower recommendation for the amount of fluoride in drinking water now that Americans get regular exposure from other sources, including toothpaste and mouthwash. Fluoride helps keep teeth healthy, but too much of it can damage tooth enamel and lead to discoloration — a condition known as fluorosis that affects about 40 percent of adolescents, according to one federal study.