Anti-fluoride activists love to trot out studies where no increase in tooth decay was found after community water fluoridation (CWF) ceased. They are cherry-picking, of course, because they ignore the studies which do show a decline in dental health. I have written about this before in What happens when fluoridation is stopped? and Anti-fluoridationist’s flawed attacks on Calgary study.
So I am pleased to see a new, just published, review of fluoridation cessation studies. Also pleased that it confirms my impression of the literature.
In short, this review concluded that:
“Overall, the published research points more to an increase in dental caries post-CWF cessation than otherwise.”
The study is published in this paper – it’s open access so you can download a pdf or see the full text:
Mclaren, L., & Singhal, S. (2016). Does cessation of community water fluoridation lead to an increase in tooth decay ? A systematic review of published studies. J Epidemiol Community Health 2, 1–7.
Unsurprisingly, these sort of studies have problems – humans cannot be treated as laboratory rats. Researchers must rely on ordinary data for dental health collected before and after cessation.
Nevertheless, these researchers managed to find 15 instances of cessation occurring in 13 countries and reported in 29 publications. Several of these were excluded because they did not consider specific cessation effects but reported on the enduring benefits of CWF even after cessation when children were exposed to CWF in the first 4 years of life. Evidence supporting a beneficial systemic effect of CWF in developing teeth. Another instance was excluded because of the complexity of its reports results didn’t enable any conclusion about effects.
Of the remaining situations, eight showed an increase in tooth decay after CWF was stopped. These occurred in Europe, Asia and North America. This paper was obviously submitted before the publication of the Calgary cessation study (Measuring the short-term impact of fluoridation cessation on dental caries in Grade 2 children using tooth surface indices) which also showed an increase in tooth decay (see Anti-fluoridationist’s flawed attacks on Calgary study for a discussion of this paper). So there are really nine instances showing an increase in tooth decay.
The other three instances did not show an increase in tooth decay. These occurred in East Germany, Finland and Cuba. These last three are, of course, the only studies anti-fluoridationists ever mention.
It’s worth quoting an observation from the paper which could help explain these different results:
“Importantly, in all three interventions, there were other factors which could have contributed to findings observed. In Finland, the CWF-cessation community started to provide fluoride tablets to children postcessation. In East Germany, postcessation fissure sealants were paid for by statutory health funds. In Cuba, postcessation, all children received fluoride mouth rinses fortnightly, and children aged 2–5 years received 1–2 fluoride varnish applications annually. Those initiatives could have offset an impact of cessation on dental caries.”
This is a really useful review as the cessation literature has not been properly reviewed before. For example, the recent Cochrane Review only considered one cessation study and concluded: “there is insufficient information to determine the effect of stopping [CWF] on caries levels.” The authors stress the need for researchers to take advantage of research opportunities presented by CWF cessation.
The authors stress the need for researchers to take advantage of research opportunities presented by CWF cessation ( there is a lot of it about in some countries). The also say there is a need for information on how cessation impacts different socio-economic groups and how decisions about cessation are made.
CWF cessation studies are just one area where anti-fluoride campaigners cherry-pick the literature. This example underlines why readers must always treat claims made by these campaigners critically. Always look at the original studies, the data, other treatments, etc. And check other research these campaigners are hiding.