Fluoride has been credited with a dramatic drop in tooth decay for the past 50 years. But now experts think some infants might be getting too much fluoride.

An infant doesn't even have baby teeth, when adult teeth start to form in the jaw. But by the time those adult teeth are visible, there's a slight chance they'll be discolored. It's called fluorosis. The blotchy uneven appearance is caused by over-exposure to fluoride.

According to the American Academy of Pediatric Dentistry, evidence has clearly shown over the years that fluoride has successfully and dramatically decreased the amount of cavities that we as a society get.

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Too much fluoride in drinking water can cause fluorosis when teeth later emerge.

Even so, studies indicate that up to half of infants could be exposed to enough fluoride in drinking water to risk mild fluorosis in adult teeth. Now the American Dental Association is offering new recommendations for infants.

They say breast feeding is best. And if you mix your own infant formula, you can buy fluoride-free water to reduce risk of fluorosis.

Fluoride toothpaste can also be a culprit, because toddlers often swallow it.

"Parents should be the ones placing the toothpaste on the toothbrush for their children, and just a small pea sized amount,” said Dr. Bill Osmunson, a Bellevue dentist.

He says some patients can need repeated, costly cosmetic repair. He sides with critics who question fluoride's safety in drinking water. And he's active in efforts to have it removed.   

According to Osmunson there are other ways to keep teeth healthy: limit the soda pops, sugar foods and candies. Even sticky snack foods like raisins are not good.

However, Dr. John Liu of the American Academy of Pediatric Dentistry says the science behind fluoride safety and effectiveness is strong, and parents shouldn't overly worry about ruining their child's smile.

"Even the cases where I do see fluorosis, they are so minor that no cosmetic intervention is needed,” he said.

If you're not sure whether your local water is treated with fluoride you can find out by contacting your local water district.

The American Dental Association also advises against fluoride supplements for infants under six months of age.