Is fluoride good your teeth?

DEAR DOCTOR K:

I’ve read that we need fluoride for healthy teeth. But I’ve also heard that fluoride can be dangerous. Can you help me sort this out?

DEAR READER:

There is no treatment that doesn’t carry some risk along with the benefit. The question always is how the benefit compares to the risk.

What’s the risk with fluoride? Curious young kids can overdose on fluoride if they get their hands on it. They might consume improperly stored fluoride tablets. Or they might eat a large amount of a fluoridated toothpaste, or drink a large amount of fluoridated mouth rinse.

On the other hand, for most children and adults, fluoride — in appropriate amounts — is a powerful ally in the fight against tooth decay. Its benefits far exceed the risks. And the risks are nil if you are careful about keeping fluoride out of the reach of young kids.

Fluoride is a common mineral found in soil, all of the Earth’s water sources, and a variety of foods, from black tea to fruit juice to canned crab. Fluoride helps teeth resist being broken down by acid from plaque bacteria. (Plaque is the sticky film that coats our teeth between brushings.)

Fluoride also boosts the body’s ability to rebuild tooth enamel when acid-producing bacteria dissolve it. This new enamel is actually harder and more decay-resistant than the enamel on the original surface of the tooth. in addition, fluoride seems to limit the ability of plaque to stick to the tooth surface.

Children and adults can help prevent tooth decay by getting some fluoride every day. One of the simplest ways to get fluoride is by drinking water that contains it, either naturally or because fluoride has been added to it. Another way is by using toothpaste that contains fluoride. (Most brands on the market contain it.)

If you drink mostly bottled water, check to see if it contains fluoride. Most brands don’t contain enough, and some don’t contain any at all. Some home water treatment systems filter out fluoride.

Most communities in the United States add fluoride to their drinking water. If your community doesn’t, or if you prefer to drink bottled water, or if your filter removes fluoride, you may need to get fluoride from other sources.

As I mentioned, getting a lot of fluoride can be deadly. But an adult would need to drink 5,000 to 10,000 glasses of fluoridated water in one sitting to take in enough fluoride to be at risk. Anyone trying to drink that much water would get sick well before they got close to drinking that amount. (Yes, you can make yourself very sick by drinking huge amounts of pure water, just from the water.)

A minor drawback to using fluoride is that it can discolor tooth enamel. Usually, the discoloration is nearly unnoticeable. Sometimes, heavier mottling and brown blemishes occur if parents use too much fluoride while a young child’s permanent teeth still are forming in the gum. This unusual situation occurs typically in small towns that naturally have more than one-part-per-million concentration of fluoride in their drinking water. But staining doesn’t affect how the teeth function or their long-term health.