Fluoride Action Network

Tooth Decay

"The magnitude of fluoridation's effect is not large in absolute terms, is often not statistically significant and may not be of clinical significance." - Dr. David Locker, University of Toronto.

Modern Fluoridation Studies

Tooth decay rates throughout the western world have declined at a steep rate over the past 50 years, irrespective of whether a country fluoridates its water or not. This fact has invited new scrutiny into the necessity and effectiveness of water fluoridation, particularly in light of the discovery that — in contrast to previous belief — fluoride’s primary benefit to teeth comes from topical, not systemic, application.

The scrutiny of fluoridation’s alleged benefits has also been further fueled by a series of large scale studies which sharply contradict the findings of the early fluoridation studies. These new studies indicate that:

  1. The early studies that “proved” fluoridation’s benefits were of extremely poor quality.
  2. Fluoridated water does not reduce the number of decayed teeth.
  3. Fluoridated water has a trivial effect on the number of decayed tooth surfaces.
  4. Total daily fluoride intake is not significantly related to tooth decay.
  5. Tooth decay rates do not increase when fluoridation stops.
  6. Fluoridation does not prevent oral health crises in low-income areas.
  7. Fluoridation is much more likely to cause dental fluorosis than reduce tooth decay

Fact 1:.

The early studies that “proved” fluoridation’s benefits were of extremely poor quality

A number of studies have purported to demonstrate very large benefits from drinking fluoridated water. In 2000, these studies were critically reviewed by an expert committee (the “York Review”) and found to be of extremely poor quality. Few of the studies controlled for other factors (e.g., poverty) that can greatly affect tooth decay, and no study was a “randomized controlled trial” — the gold standard in medical research and required before most drugs can enter the market. The scientists who participated in the review, including Sir Iain Chalmers,  have publicly stated their surprise at the “poor quality” of research they found.

Fact 2:

Fluoridated water does not reduce the number of decayed teeth

In the early days of water fluoridation, researchers studied its effectiveness at reducing “DMFT” (Decayed, Missing, or Filled Teeth”). Although early researchers stated that fluoridation reduced DMFT by over 60% (Hodge 1950), modern, large scale studies have repeatedly failed to detect any significant difference in DMFT between fluoridated and non-fluoridated areas. (Diesendorf 1997) One of the first studies to demonstrate this was a 1986-87 national study of oral health by dentists at the National Institute of Dental Research (NIDR), which examined over 39,000 children in 84 areas of the U.S. When the results of NIDR’s study were obtained through a Freedom of Information Act request, it was found that American children who had lived their whole lives in fluoridated areas did not have less tooth decay than children who had lived their entire lives in non-fluoridated areas. Other studies have since reported the same result.

Fact #3:

Fluoridated water has a trivial effect on the number of decayed tooth surfaces

Due to the difficulty of detecting differences in tooth decay using DMFT, most studies on water fluoridation now use a more sensitive measure called DMFS, which focuses on the number of affected tooth surfaces. Although differences in tooth decay have been found when using DMFS as the measure, the magnitude of the effect is extremely small. In the NIDR’s national survey, for example, NIDR statisticians reported an average difference between fluoridated and non-fluoridated areas of just 0.6 tooth surfaces, which is less than 1% of the 100+ tooth surfaces in a child’s mouth. Other large, modern studies have found similar results, with some studies finding no difference, and others finding average differences of just 0.12 to 0.3 tooth surfaces per child.

Fact #4:

Total daily fluoride intake is not significantly related to tooth decay.

A multi-million dollar, NIH-funded study found that total fluoride intake from birth through nine years of age has no significant effect on whether the child will develop a cavity. This is the first time tooth decay has been investigated as a function of individual exposure (as opposed to mere residence in a fluoridated community). More recently, the Iowa team has reported that the fluoride level in a child’s water from birth through 13 years of age does not significantly predict the presence or absence of tooth decay.

Fact #5:

Tooth decay does not go up when fluoridation is stopped.

Where fluoridation has been discontinued in communities from Canada, the former East Germany, Cuba and Finland, the rate of tooth decay did not increase. Instead, the rate of tooth decay continued to decline.

Fact 6:

Fluoridated Does Not Prevent Oral Health Crises in Low Income Communities. 

In the United States, the Surgeon General has identified a “silent epidemic” of tooth decay in low-income communities and communities of color, which health departments across the country have called an “oral health crisis.” Many of the communities with oral health crises, particularly in urban areas, have been fluoridated for decades. In Cincinnati, for example, the city’s Dental Director described the state of oral health after 23 years of water fluoridation as follows:

‘We cannot meet the demand. It’s absolutely heartbreaking and a travesty. We have kids in this community with severe untreated dental infections. We have kids with self-esteem problems, and we have kids in severe pain and we have no place to send them in Cincinnati. People would be shocked to learn how bad the problem has become.’”

It has become evident, therefore, that water fluoridation cannot not prevent the disastrous effects that poverty and a broken health care system can have on oral health. This has been made further evident by studies showing that fluoridation does not prevent baby bottle tooth decay from occurring in low-income communities. Low-income communities need dental care, not cheap industrial chemicals in their water.

Fact #7:

Fluoridation is much more likely to cause dental fluorosis than reduce decay

When the water fluoridation program was endorsed by U.S. health authorities in the 1950s, proponents argued that fluoridation would produce a very sharp reduction in tooth decay with only a very minimal effect on dental fluorosis. This prediction did not prove true — a fact this is readily apparent when comparing the predicted relationship with the actual relationship (as observed in the NIDR’s national survey):

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