Fluoridated Water Does Not
Prevent Tooth Decay

by Mark D. Gold

I will cover two areas in this section. I will list a selection of information which shows that fluoridation is not helping to prevent dental decay. At the same time, I will comment on how the Dental Trade Organizations have used flawed studies to convince dentists that fluoridation was useful. I will preface those comments with:

"ALERT #x"

For this discussion, remember that in the U.S., Trade Organizations like the American Dental Association (ADA) recommend that water should be fluoridated to 1 part per million (1ppm), although they allow for variations depending upon the climate (.7 ppm - 1.2 ppm).

Also, please remember that the original studies by H. Trendly Dean on fluoridation which led to the decision to allow fluoridation of municipal water supplies

  1. Were worthless by his own criteria.
  2. Did not consider other minerals in the water.
  3. Did not consider the differences between "natural fluoride" (e.g., CaF) and fluoride waste products (e.g., NaF).
  4. Only reported his chosen selection of data -- a subsection of the data gathered.
  5. Had little or no statistical analysis.
  6. Included no safety experiments except for dental fluorosis.

  1. Yiamouyiannis, J. "Water Fluoridation and Tooth Decay: Results From the 1986-1987 National Survey of U.S. Schoolchildren" Fluoride, Journal of The International Society for Fluoride Research (Volume 23, No. 2; April 1990; pp 55-67).

    This study showed, once and for all, that fluoridation of the U.S. water supply was worthless, at best.

    Summary: Data from dental examinations of 39,207 schoolchildren, aged 5-17, in 84 areas throughout the United States are analyzed. Of these areas, 27 had been fluoridated for 17 years of more (F), 30 had never been fluoridated (NF), and 27 had been only partially fluoridated or fluoridated for less than 17 years (PF). No statistically significant differences were found in the decay rates of permanent teeth or the percentages of decay-free children in the F, NF and PF areas. However, among 5-year-olds, the decay rates of the deciduous teeth were significantly lower in F than in NF areas.

    Table 2

    Average-age-adjusted DMFT [Decayed, Missing, Filled Teeth] rates for 39,207 U.S. schoolchildren and 17,336 lofe-long resident schoolchildren in 84 areas throughout the United States. Standard deviations are given in parentheses.

    ---------------- Total --------------- Life-Long --

    No. of
    No. of
    DMFT No. of

    As you can see, there are no statistical differences in decayed, mission, or filling teeth for U.S. children aged 5-17.

    Yes, there is a stastically significant advantage in DMFT for 5-year-olds. However, by age 6, that advantage disappears. The suspected cause for the one-year, temporary benefit is slightly delayed tooth eruption in fluoridated water drinkers. Whatever the cause, remember, there are no statistically significant difference after age 5.

    ALERT #1

      Recently, Brunelle used the same data to "prove" a statistically significant advantage in dental decay in fluoridated sections of the U.S. ("Caries Attack in the Primary Dentition of U.S. Children" J. Dent. Research 69(Special Issue): 180 [Abstr. No. 575], 1990.) However, Brunelle used only one year (5-year-olds) of the data that was gathered in the national survey: 5 to 17 years old! As was mentioned above, this slight advantage in fluoridation disappears after age 5 and is likely caused by slightly delayed tooth eruption in 5-year-olds. By picking tiny subsections of data collected, a researcher can prove whatever he or she wants! This is not the only time this flawed data analysis technique was used in fluoridation research.

      Also, this study points to the fact that other studies which relied to a large extent on 5-year-olds and few older children may also show skewed results.

    ALERT #2

      In another poor study, Brunelle and Carlos used more complete survey data to seemingly "prove" the advantages of fluoridation. ("Recent Trends in Dental Caries in U.S. Children and the Effect of Water Fluoridation" J. Dental Research, 69(Special Issue): 723-728, 1990). This time Brunelle used more data than above, but made many other sloppy errors as pointed out by Yiamouyiannis.

      • "It contains extremely serious errors. For example, by a cursory inspection, we found two values that are off by 100% or more. In their Table 9, the DMFS figure for life-long F exposure residents of Region VII should be about 3, not 1.46 as reported. Form their Table 3, the percent of 5-year-olds who have caries is 1.0%, not the 2.7% that can be calculated from the table. When I pointed out this error to Dr. Carlos he admitted that only 19 out of the 1851 5-year-olds had caries (19/1851 = 1%), but refused to make the correction."

      • "It fails to report the tooth decay rates for each of the 84 geographical areas surveyed. This covers up the fact that there is no difference in the tooth decay rates of the fluoridated and nonfluoridated areas surveyed. The Brunelle/ Carlos study even fails to list the areas studied. As a result, they produce misleading illustrations; for example, their Figure 3 implies that Arizona and New Mexico have the lowest tooth decay rates, when, in fact, not a single area was surveyed in either of the two states."

      • "It fails to do the statistical analysis (or even provide the data, i.e., the standard deviation and sample number) necessary to determine whether the values found for F and NF areas are significantly different."

      • "It fails to report the data for the approximately 23,000 schoolchildren who were not life-time residents of either the F or NF areas (the partially fluoridated, PF group)....

      He goes on to point out other significant flaws in this Brunelle and Carlos study.

  2. Steelink C., Fowler M, Osborn M et al. Findings and recommendations of subcommittee on fluoridation. City of Tuscon AZ 1992 (PO Box 27210).
    Also see: Chemical and Engineering News (7/27/92).

    A study of Tuscon elementary children was performed by Cornelius Steelink, Professor Emeritus, Department of Chemistry, University of Arizona. The study was performed in order to determine the "benefits" of water fluoridation.

    They compared tooth decay versus fluoride content in a child's neighborhood drinking water for 26,000 elementary school children.

    Here are the results:

      "...a positive correlation was revealed. In other words, the more fluoride a child drank, the more cavities appeared in the teeth.

      He goes on to state:

      "Since this was an unusual result, our subcommittee looked for other relevant factors. Family incomes was compared to tooth decay. An excellent inverse relation was found for these 26,000 children: the higher the income, the lower the number of decayed teeth. Other anecdotal evidence gathered by our committee included lack of access to dental facilities, poverty, diet, and oral hygiene as contributing factors to tooth decay in this group of children.

      In the final report, the subcommittee stated that there was no obvious relation of fluoride content in municipal water to the prevention of tooth decay in Tucson, and because there are multiple causes of tooth decay, a decision to fluoridate would still leave pockets of poor dental health in Tucson. .... However, when the full Citizens Water Advisory Committee reviewed our report in June 1992, it recommended (on a split vote) that the city council go ahead and fluoridate the water. The principal argument for this vote was: 'Even though fluoridation doesn't appear to be effective, let's rely on the advice of the public health officials. After all, they're the experts.'"

    I saw a graph with the percentage of tooth decay plotted against fluoride concentration. As soon as it goes over .6 ppm, the decay goes way up.

  3. "Influence of social class and fluoridation on child dental health" Community Dentistry and Oral Epidemiology 13 37-41 1985.

    This study examined the influence of social class (environmental and lifestyle factors, diet, etc.) and fluoridation on dental health. It showed that dental health as continued to improve equally in both fluoridated and unfluoridated areas and that the level of dental health was strongly related to social class.

    A similar result (with slightly better teeth in unfluoridated areas) was found in Colquohoun J. "Child dental health differences in New Zealand" Community Health Studies 11 85-90 1987.

    ALERT #3

      The last two sections (2, 3) show that it is not lack of fluoride that leads to decay but things such as "lack of access to dental facilities, poverty, diet, and oral hygiene." A number of studies were performed by persons interested in keeping the fluoridation myth alive. One way to skew the results was to compare two areas, one fluoridated and one non-fluoridated but not take into account other factors. If a non-fluoridated area with lack of dental facilities, poverty, poor diet and hygiene was compared against a nearby, yet more well-to-do fluoridated area, it becomes very easy to "prove" (wink, wink) that fluoridation is beneficial. This type of nonsense was done several times in order to keep the fluoridation myth alive.

      One of many studies that have this flaw is:

        Jackson, D., et al. "Fluoridation in Anglesey 1983: a Clinical Study of Dental Caries" British Dental Journal 1985: 158: 45.

      The two areas being compared, while adjacent, were vastly different.

  4. Ziegelbecker RC, Ziegelbecker R. "WHO data on dental caries and natural water fluoride levels." Fluoride 26 263-266 1993.


    Ziegelbecker R. "Fluoridated water and teeth" Fluoride 14 123-128 1981

    Both of these studies are from large data set showing that there is no correlation between caries and fluoride concentration and no improvement in dental health from fluoride. In the 1981 study, for example, Ziegelbecker made of random sampling of all available data on caries prevalence. He selected 48,000 12-14 year-old children from 136 community water supplies in seven countries.

  5. Diesendorf M. "The mystery of declining tooth decay" Nature 322 125-129 1986.


      Large temporal reductions in tooth decay, which cannot be attributed to fluoridation, have been observed in both unfluoridated and fluoridated areas of at least eight developed countries over the past thirty years. It is now time for a scientific re-examination of the alleged enormous benefits of fluoridation.

    Mark Diesendorf, an applied mathmetician, expert in research design, and health researcher at the Human Sciences Program at Austrailian National University showed in this analysis that the decline in dental decay in fluoridated areas has not been greater than in non-fluoridated areas. He used 24 studies of unfluoridated areas to prove this.

    Diesendorf isn't the only expert to realize the fact that fluoridation is not what lead to the improvement in dental health. In the April 1988 issue of the Journal of the American Dental Association, Stanley Heifetz of the NIDR wrote, "the current reported decline in caries in the U.S. and other Western industrialized countries has been observed in both fluoridated and nonfluoridated communities, with percentage reductions in each community apparently about the same."

    ALERT #4

      There have been numerous studies that have measured improvement in dental health in fluoridated areas. Soon after the publication of these studies, press releases often hail the "enormous dental health improvements due to fluoridation." Had the authors of these studies compared the results to non-fluoridated areas and taken a large sample size (as was done in the Diesendorf and Ziegelbecker studies), there would show no significant improvements in dental health compared to nonfluoridated areas.

      The moral is to beware fluoridation studies that compare it against nothing and don't account for other factors such as diet. They are nothing more than glorified press releases.

  6. Teotia SPS, Teotia M. "Dental caries: a disorder of high fluoride and low dietary calcium interactions" Fluoride 27 April, 1994 (page 61).

    This was a 20-year study (1973-1993) of 400,000 children in India. It shows that the higher the fluoride concentration in water, the more caries occured. In addition, this study shows that adolescents ingesting fluoridated water and a low calcium diet have extremely high rates of fluorosis and dental decay.

  7. Imai Y. "Study of the relationship between fluoride ions in drinking water and dental caries in Japan" Japanese Journal of Dental Health 22 144-196 1972.

    This study of 22,000 Japanese schoolchildren showed that above 0.4 ppm the decay rate increased significantly.

    When the fluoride concentration was below 0.2 ppm the decay rate also increased significantly. This was thought to be caused by the lack of calcium in the water when the fluoride was less than 0.2 ppm.

    Needless to say, Japan, like the large majority of countries (including industrialized countries) does not fluoridate their water supply.

    8) Colquhoun, J. "Is There a Dental Benefit From Water Fluoride?" Fluoride Vol. 27, No. 1 13-22, 1994.


      Dental data collected for virtually all New Zealand children, as well as comprehensive data from other countries, indicate no dental benefit from water fluoridation. Claims for a benefit depend on small-scale studies of selected samples of children. The classic fluoridation research is critically re-examined.

    This study, like the Yiamouyiannis study of 39, 207 US schoolchildren, proves that fluoridation in New Zealand was and is worthless. The data was collected for 98% of all 12-13 year-old children and 5 year-old children in New Zealand.

    Here is the table from the study showing the main population centers.


    ---------------------- 12-13 year olds -------- 5 year olds ------

    Center No. of
    free %
    No. of
    free %
    Christchurch(5822)37%1.9 (3849)55%1.8
    Auckland(11464)33%2.0 (9611)53%1.8
    Hamilton(2689)30%2.3 (2266)47%2.3
    Palmerston Nth(1025)31%2.3 (950)55%1.8
    Wellington(4237)36%1.8 (3344)58%1.6
    Dunedin(1168)29%2.2 (994)56%1.5

    This must-read study/report goes on to show the major flaws in so many pro-fluoridation studies. Some notable excerpts:

      "The New Zealand Department of Health, a long-time advocate of water fluoridation, presented the 12-13-year-old data in its annual reports by comparing the combined fluoridated with the combined nonfluoridated areas of New Zealand [Annual Reports, Department of Health, from 1981]. The differences were very small (only 1% for the caries-free percentage in each kind of area, and less than half a tooth for the mean number of decayed, missing or filled teeth) but suggested a small benefit from fluoridation. However, the areas being compared were dissimilar, one being mostly urban with higher average incomes, and the other mostly small-town-rural with lower average incomes. When similar kinds of communities were compared, the teeth were actually slightly better in the nonfluoridated areas."
      "Other New Zealand studies, of small samples of 5-year-olds 7-year olds and 9-year-olds claimed that there was a small but significant benefit resulting from fluoridation. These studies, which were contradicted by the data collected for all 12- and 13-year-olds, were discussed in my earlier study.... Since then, the authors of the 9-year olds study and its follow-up have admitted that their low-fluoride sample used for comparison 'probably was biassed towards children of dentally unaware and low socioeconomic parents -- a factor that would tend to increase their caries.'" [See full text for references.]
      "Recently another small-sample non-blind study has been published, claiming to demonstrate the benefit of fluoridation for the whold of New Zealand [New Zealand Dental Journal 88 9-13 1992]. Samll samples of 5-year-old children were examined, from selected fluoridated and non-fluoridated communities in otago and cantebury provinces. The results claimed up to 60% less tooth decay in the fluoridated communities.... But, when I obtained the School Dental Service data for all 5-year-olds in the fluoridated and nonfluoridated areas of these two provinces...the claimed differences did not exist." [The authors of the study had simply chosen the worst nonfluoridated city to compare again on best fluoridated cities.]

    He goes on to examine the history of fluoridation research which is full of flawed studies beginning with HT Dean's studies in the 1930s and 1940s. Any student of dental science should read this review.

  8. Other

    • Ray SK, Ghosh S, Tiwari TC et all. "An Epidemiological study of caries and its relationship to fluoride content of drinking water in rural communities near Varanasi" Indian Journal of Preventive and Social Medicine 12 154-158 1981.

    • "Fluoridation of Water", Chemical and Engineering News, 8/1/88

      "Alan S. Gray, former director of the Division of Dental Health Services for the British Columbia Ministry of Health, finds, for example, that the average number of decayed, missing, and filled permanent teeth in British Columbia, where only 11% of the population uses fluoridated water, is lower than in parts of Canada where 40 to 70% of the people drink fluoridated water. School districts in the province with the highest percentage of children with no tooth decay are totally unfluoridated. [See Gray, AS J. Canadian Dent. Assoc. 53:763 (1987).]

    • Caries incidence in children with 2.0-3.5 ppm fluuoride in water is the same as that found in 0.20 ppm areas in Tanzania according to several studies. See Community Dental Oral Epidemiology, Volume 14, page 94-98 and page 99-103 and Scandinavian Journal of Dental Research, Volume 96, page 385-389.

    • There are many other studies which show that fluoridation does not and has never prevented dental decay. Please see the fluoride web page for a listing of other studies.

    ALERT #5

      One other method that is used to make it appear that fluoridation is useful are "defluoridation" studies. When fluoride is removed from the water supply, some studies appear to show a large increase in DMFT rate a few years later. What is usually not said is that the increase is due almost completely to a change in dental practices such that the decay part of DMFT (decayed, missing, filled teeth) does not increase at all. Also, some of the studies are conducted on young children (i.e., five year-olds) and we would expect an increase in decay rate for that age group since tooth eruption is no longer delayed by fluoridation.

      In addition, pro-fluoridationists sometimes refer to fairly recent small studies purporting to show decreases in DMFS or DMFT. This is irrelevant. It is relatively easy for some researchers to select areas where they know they will get the results they're looking for. As you can see from the above-mentioned extremely large-scale studies, there is no decrease in DMFT, but possible an increase. There are no recent, large-scale studies (i.e., 1985-1995) which show a decrease in DMFT rates other than the Brunelle studies which are discussed above.


    Portland, Oregon rejected fluoridation not long ago. Albany, New York rejected fluoridation recently. Several cities and towns have thrown out fluoridation over the last few years.

    To conclude, I'll quote Virginia Rosenbaum in an article entitled "U.S. EPA Scientists Warns Nation of Hip Fractures in Elderly Caused By Fluoride"

      "Fluoridation will be banned in this country. It is in its death throes now. It just hasn't stopped kicking! Like a snake, it keeps twitching for awhile!"

    There are numerous studies showing detrimental effect from fluoridation (not only cancer and hip fractures), but you won't find those studies listed in any ADA or EPA reviews.