What does fluoride in the water do?

"I wrote this before some significant new information on fluoride in the water was discovered by the Centers for Disease Control in Atlanta, Georgia, USA, in 2005. See the article in this series entitled Something New About Fluoride to see the more up to date (and substantially different) information about fluoride in the water."

Fluoride is a naturally occurring element commonly found in water that has been in contact with fluoride bearing rock. In fact, from a historical perspective, fluoride was discovered as a substance of value to teeth about 90 years ago. At that time, virtually everyone had many cavities. In fact, the number one reason for lost time at work and at school was toothache pain from dental decay (cavities). A group of researchers noticed that people who had grown up in Colorado Springs, Colorado, had no decay at all, but their teeth were nearly black. Several notable researchers of the time spent much effort attempting to figure out why the people of Colorado Springs had teeth that were different than the teeth of people from other places. The scientists finally put it all together when they found a couple of towns in Texas with people whose teeth were in the same shape as the people of Colorado Springs (No cavities, but dark), and compared what was similar about the people and about other items in the two towns.

After finding out what was causing the teeth to resist decay, the same researchers set out to find a way to get decay resistance but not discolour teeth. They found that fluoride administered in a very small dose caused the teeth to be much less likely to decay but still have their natural non-fluoridated colour on most people. At higher doses, the surface layer of the teeth became slightly roughened causing the teeth to look opaque white. At still higher doses, fluoride caused a distinct roughening of the teeth which caused dark items in the patient's diet to discolour the teeth. They also found that only people with forming teeth realized any effect from low doses of fluoride. After the teeth erupted, low doses of fluoride really did very little or nothing. A higher dose of fluoride (at least 1000 times as high as the non-discolouring dose in the water) was required to provide decay resistance in already formed teeth.

The first municipality to artificially add fluoride to its water supply was in Michigan in 1946. At the low fluoride dose provided in the water (1 part per million), only people with forming teeth would benefit from the fluoride provided in the water. However, the cost was so low to fluoridate all the water of the community as compared with administering fluoride to only the children, that fluoridating the entire water supply was by far the most cost effective option. In Michigan in 1946, the water was fluoridated at the rate of one part fluoride per one million parts water. In the last few years, Health Canada has suggested that a somewhat lower dose of .7 parts fluoride per one million parts water actually works just about as well to prevent tooth decay, but is much less likely to discolour the teeth. Every person concentrates fluoride in the teeth at a slightly different level. Because of this, some people will have opaque white spots on their teeth from even the lower .7 parts per million concentration of fluoride while the overwhelming majority of people will not show discolouration at this level. Similarly, some people will realize more protection from tooth decay from fluoride in the water during tooth formation than others. Currently, .7 parts per million is considered by the experts to be the lowest dose that still provides an adequate level of decay prevention in forming teeth. Children growing up in a community like Kenora whose water has this level of fluoride on average will develop 30-40% fewer sites of tooth decay on the smooth surfaces of their teeth (like between them), as compared to children growing up in non-fluoridated communities. The effect is life long--even if the person moves out of the community with fluoridated water after the teeth are formed.

Public health experts widely consider fluoridation of municipal water supplies to be one of the most successful public health initiatives of all time. However, as is the case with all science, there could be negative effects that are not well understood at this point in time. Health Canada and others will continue to monitor the effects of fluoride in the water and update its recommendations as time goes on. For now, fluoride in the water continues to be one of the main weapons in the battle against tooth decay.


This article was written by Dr. Mike Christensen and published in the Daily Miner and News, and Enterprise. Local Kenora News Publicatons (1998-2006)