Fluoride: Friend or Foe?


The American Dental Association recommends brushing with a fluoride toothpaste twice a day. Many U.S. state and municipal authorities fluoridate the municipal water supply, as recommended by major national and global agencies, including the US Department of Health and Human Services and the World Health Organization.

Obviously, some important people believe that fluoride is important for public health. Why is that? And can too much fluoride be a bad thing for your teeth?

Colorado Brown Stain and the discovery of fluorosis

I’ll tell you the story of how this came to be because it’s pretty interesting.

In 1901, Dr. Frederick McKay went to Colorado Springs intending to open a dental practice there. He was astonished to find that many residents of the town had dark brown stains on their teeth. Some were so bad that they looked like “the color of chocolate candy.” This has come to be known as Colorado Brown Stain.

Yet as bad as these teeth looked, over time Dr. McKay found that these teeth actually resisted cavities very well. He also discovered that the stains were something that occurred while teeth were developing. That is, if permanent teeth came in and calcified before the stains set in, they didn’t stain later.

It turns out the cause of these brown spots was high fluoride levels in the water supply, causing what we now call “fluorosis.” While high levels of fluoride stained teeth brown, lower levels didn’t, but still provided protection against cavities.

Fluoride is protective against cavities because it helps remineralize tooth enamel that has been demineralized. That is, it easily bonds to the enamel of the tooth. Not only that, it can attract other minerals, like calcium and phosphorous, to help strengthen the tooth. By strengthening the enamel layer of the tooth, fluoride helps prevent decay.

Introducing fluoride into the water and food supply

Many decades later, the head of the Dental Hygiene Unit at the National Health Institute, Dr. H. Trendley Dean, looked further into the subject of fluoride. He wanted to know what levels were safe and whether fluoride in water would help reduce tooth decay. A test was done by adding fluoride to the drinking water of Grand Rapids, Michigan, from 1945-1960. Dr. Dean found that indeed, children born there were 60% less likely to develop cavities compared to children who did not drink fluoridated water.

In 1952, legislation was passed in Puerto Rico that would add fluoride to the water, but it was not enforced until 1998. Currently, water is not being fluoridated in the island due to budgetary constraints. However, over 200 million Americans today benefit from fluoridated water in approximately 70% of public water supplies that are fluoridated in the nation, and over two dozen countries around the world have also undertaken water fluoridation programs for public health. Efforts have been made to provide fluoride to the population through other means, too, through adding fluoride to salt (as in Jamaica and Colombia) as well as to milk, yogurt, and juice in some countries. Of course, fluoridated toothpaste is also popular all over the world, too.

Fluoride: Too much of a good thing?

Fluorosis still exists today. When too much fluoride is consumed, teeth can grow in with brown spots, just as they did in early 1900s Colorado Springs. That’s when fluorosis is severe, however; more often, it leads to white spots or streaks, which may only be visible a dental professional. But it’s important to know that these white streaks and brown spots are a cosmetic issue, not a health one.

If your permanent teeth have grown in, there’s no need to worry about fluorosis. Remember that Dr. McKay found that the spots only occurred on developing teeth. But if your child doesn’t have all their permanent teeth, and you’re concerned about fluorosis, speak with your child’s dentist or pediatrician about it.

The bottom line is this: fluoride has been shown to be protective against dental decay and too much is only a problem in young children (and even then it isn’t very widespread). Follow the ADA’s recommendation to brush with a fluoride toothpaste and don’t avoid tap water simply because you want to avoid fluoride. And as always, if you have concerns about your oral health, speak to your dentist.