Anti-fluoridation activists are always making claims that fluoridation is not effective. Even sometimes claiming that children in non-fluoridated areas have less tooth decay than those in fluoridated areas. And they will sometimes cite, or link to, scientific papers they believe support these claims.
It’s always worth checking out such claims. Check the paper, find out what it does actually report and what other factors are involved. We should approach the scientific literature intelligently and critically – not cherry pick to support our confirmation bias.
Here is an example of a paper promoted by Declan Waugh purporting to claim that dental health is a result of “social class” and not influenced by fluoridation. The paper is Colquhoun, J. (1985). Influence of social class and fluoridation on child dental health. Community Dentistry and Oral Epidemiology, 13(1), 37–41.
Of course, the role of social economic status in oral health is well known so I am not questioning that. But can that paper actually be used to prove the claim that fluoridation is ineffective or that fluoride does not play a role in oral health?
Colquhoun found no statistical difference in the caries-free percentage of children in fluoridated and non-fluoridated areas around Auckland when areas of “similar social rank” were compared. And of course anti-fluoridation activists like Declan Waugh pounce on that finding – which is supported by the data. But what other factors are involved.
If Declan had read the paper – or was at all interested in conveying the important facts – he would have seen this important note by Colquhoun:
“It should be noted, when comparing child dental health in different areas in this way, that in New Zealand all school dental clinic patients in unfluoridated areas receive routine 6-monthly topical fluoride applications, while only selected “at risk” children receive them in the fluoridated areas. Also, vigorous educational and preventive work, including encouragement of use of fluoride toothpastes, has been carried out in both kinds of areas.”
This even made it to the abstract:
“In the unfluoridated areas all the children, and in the fluoridated areas only selected children, had received regular topical fluoride treatments. In both areas the use of fluoride toothpastes and oral hygiene had been encouraged.”
This information is vital to the conclusion. Colquhoun had allowed for the “socioeconomic variable” but had not allowed for the different dental treatments of the two groups of children. The fact that all children of non-fluoridated areas were receiving 6-monthly topical fluoride applications and most children from fluoridated areas were not is an important factor.
Maybe Colquhoun’s paper can be used to argue that other fluoride treatments may be as effective as community water fluoridation – but his data certainly does not support the claim that fluoridation is ineffective. I guess there was a bit of confirmation bias on Colquhoun’s part – but certainly cherry-picking and confirmation bias on Waugh’s part.
Community water fluoridation is only one of the ways to improve oral health using fluoride. Regular brushing with fluoridated toothpaste, fluoridated salt or milk, and regular fluoride dental treatments also work. These other sources and treatments should always be considered when evaluating this sort of data.
Maupomé, et al (2001) made this point in their conclusions from a study on patterns of dental caries after cessation of water fluoridation. They wrote:
“Our results suggest a complicated pattern of disease following cessation of fluoridation. Multiple sources of fluoride besides water fluoridation have made it more difficult to detect changes in the epidemiological profile of a population with generally low caries experience, and living in an affluent setting with widely accessible dental services. There are, however, subtle differences in caries and caries treatment experience between children living in fluoridated and fluoridation-ended areas.”
An intelligent and critical approach to the scientific literature means we should always keep this in mind when reading papers like this.
And we should never take the claims made by activists like Declan Waugh at face value.