Fluoride: Friend or Foe?
In my hometown of Grand Rapids, Michigan, there sits a monument to a scientific study performed 70 years ago which changed the face of dental care. This study involved the public use of fluoride in drinking water to prevent cavities.
Now, fluoride is commonplace in routine preventative dental care. Current practice however, has evolved with some debate, and some critics. Let's discuss the current understanding and recommendations for fluoride use in strengthening our teeth against cavities.
The Story of Fluoride and Teeth
The story of dental fluoride began a bit unexpectedly in 1901 when a young dental school graduate named Frederick McKay moved to Colorado Springs, Colorado to start a dental practice. He couldn't help but notice that many of the children around town had brown stains on their teeth. Nowhere in the dental literature of the day could he find mention of such dental ailments. Despite extensive observations about the epidemiology of the region, no immediate cause to the problem was found other than the fact that 90% of children born in the area developed "Colorado Brown Teeth." On the other side of the spectrum, people with adult teeth who moved into the area had no risk of getting brown stains on their teeth. Interestingly, the children with brown teeth had a fraction of the cavities so typical of the day.
A breakthrough finally came in 1923 in Idaho when children started getting brown teeth shortly after a new water source was tapped for public use. It was the water. The water source was abandoned and childrens' teeth returned to normal. Extensive analysis finally revealed that the water samples from Colorado Springs and the Idaho water source contained fluoride, an unusual finding in naturally occurring water.
Years of research exquisitely linked fluoride to the brown teeth and revealed the threshold amounts which left no stains in young, growing teeth. And through this work, the association with reduced rates of cavities was not forgotten. In the 1940's it was felt that a public health trial was the next step to see if a small amount of fluoride in drinking water would reduce cavities without any ill effects. After much debate, the city of Grand Rapids, Michigan stepped up to "drink the water," becoming the first place with fluorinated public drinking water. 30,000 school children were monitored over the next several years. After 11 years, the results were revealed. Children born after the project started had a 60% reduction in cavities! (1)
How Does Fluoride Work?
Cavities are about sugar, bacteria and acid. The sugar we eat (fruit sugar, milk sugar or table sugar) is potentially metabolized in the mouth by a unfriendly bacteria that lurks on the teeth called streptococcus mutans. The sugar is metabolized to lactic acid which leaches minerals from the enamel on the teeth. The main naturally occurring mineral is a compound called hydroxyapatite. With this acid exposure, a void or pocket develops on the tooth which forms a harbor for the strep mutans and a vicious cycle ensues. With time, the whole pH balance of the mouth can change and strep mutans can push out all the normal healthy mouth bacteria. Cavities can progress to abscesses, more widespread infection and even death if untreated.
Fluoride blocks the effects of bacteria and the acidic byproduct. When fluoride is exposed to a tooth, it converts hydroxyapatite to fluorapatite. This substance binds to the superficial enamel and protects better than what the body had there before. Fluorapatite is not only stronger than hydroxyapatite, it is more resistant to acid breakdown and has antibacterial properties.
Too Much of a Good Thing
The key to success with fluoride lies in getting the appropriate amount to protect the teeth while not getting too much to be harmful. The tiny amount in fluoridated public drinking water is such that the optimal amount will be taken in as children begin drinking water and then consuming more as they age. Things can get complicated however when fluoride supplements are taken and fluoride toothpaste is used and other environmental exposures occur. (Such environmental exposures can occur due to industrialization with aluminum production and pesticides.)
The condition of fluorosis (getting too much fluoride) is heralded by white flecks seen primarily on the frontal teeth. Severe cases are quite rare and involve the brown staining of the teeth and can eventually lead to weakening of the bones.
Evolution of Use
The increase of fluoride in our day-to-day environment and a further understanding of how fluoride works has led to some evolved recommendations for optimal preventative use. Rather than ingestion into the body, it is now felt that fluoride exposure to the enamel, as it is taken into the mouth, is the key to strengthening the enamel. The use of daily ingested tablets and the fluoride gel-in-tray treatments for children without fluoridated home tap water has fallen out of favor. A varnish product is now used and applied at the dentist.
Most dentists now recommend fluoride exposure in the absence of fluoridated water occur with a swish and spit fluoride rinse such as Act. Or, it is a common recommendation among experts to brush with fluoridated tooth paste, spit and then refrain from rinsing before bed. This will expose the teeth to a reasonable amount of fluoride. For those with fluoridated water, however, this minute regular exposure is the best and swallowing the water poses no harm. In recent years, government agencies recommended reducing the fluoride content of public water from 0.7 - 1.2 parts per million to 0.7 parts per million due to increased exposure from other sources. (2) The effects of removing fluoride from the water were seen in Galesburg, Illinois where cavities in children increased by 38% in the years following.
With any government initiative there seems to be a number of suspicions, conspiracies and contrarian viewpoints. There are active movements to remove fluoride from public drinking water claiming that it is harmful causing cancer, thyroid problems and other ailments. (3)
However, after reviewing the literature on both sides I feel that the findings are quite in favor of fluoride for teeth with no significant ill effects. It certainly is not a financial gain ploy on the part of the dentists or the government. I've heard a lot that dental problems pay for the local dentist's sports car or kid's tuition, but fluoride leaves the dental chairs more empty than not.
Fluoride helps prevent cavities in growing teeth. Like many things in our world, a balance needs to be achieved regarding fluoride exposure to maximize the good and stay away from any ill effects. The use of fluoride has been a public health triumph, preventing a significant amount of dental issues. Recommendations for fluoride have evolved significantly over the years toward the present recommendations. Talk to your dentist to review your individual fluoride exposure and needs.