By Ken Perrott 04/01/2016 2


You should not trust what you read on the web – especially if you read it on a site like Free Thought Project.com. And if the article is citing a scientific paper to give it authority you can be certain it misrepresents the paper.

Here is yet another example of this. An article citing a research paper as “proof” that fluoridation does not work – yet the paper doesn’t even include the word fluoride or fluoridation!

The Free Thought Project.com article is Study Shows Brits Have Way Better Teeth than Americans – And Far Less Fluoride in the Water
and it cites, but misrepresent this paper:

What did the paper report?

This is the paper:

CC Guarnizo-Herreño, G Tsakos, A Sheiham et al. Austin Powers bites back: a cross sectional comparison of US and English national oral health surveys.

It’s available in full text so you can check for yourself.

It examines “the longstanding belief in the United States that the British have horrible teeth, much worse than US citizens.” And it concludes:

“The oral health of US citizens is not better than the English, and there are consistently wider educational and income oral health inequalities in the US compared with England.”

So – nothing about fluoride, but information on social inequalities which are known to be a factor in oral health. But this will not stop anti-fluoride campaigners using this in their campaigns – while ignoring the important conclusions about the role of socioeconomic inequalities in oral health.

What was measured?

The study considered only one clinical measure of oral health status – the number of missing teeth. The other two outcomes considered were “self-rated oral health” and “oral impacts on daily life.” Only participants 25 years and older were selected. The study used data from the English Adult Dental Health Survey and the US National Health and Nutrition Examination Survey.

The influence of dietary fluoride intake was NOT considered, but socioeconomic factors were. In particular educational attainment and household income.

What was found?

In summary:

  • The number of missing teeth were significantly higher in the US than in England.
  • Self-rated negative oral impacts on daily life were more prevalent int England than the US
  • Self-rated less than good oral health was not significantly different between the two countries.

There was an interesting difference with age. The number of missing teeth and the numbers with no teeth were higher in the US for the age group 25-64. Yet the number of missing teeth were higher in England for the over 65 age group.

Socioeconomic factors showed statistically significant effects on all three outcomes as illustrated in this figure from the paper. The “relative index of inequality” was effectively a measure of how the outcome increased as inequality in education or income increased in each country.

Conclusions

Given the prevailing beliefs in the US it may be a little surprising that the study found English oral health better than in the US – at least for measurements related to missing teeth. However, it is not suprising that socioeconomic inequalities influence the oral health of a nation – with, of course, those at the bottom of the heap having the poorer oral health.

I guess it is also not surprising to find that there are “consistently wider educational and income related oral health inequalities in the US compared with England.”

So, there is probably an argument there for improved welfare policies and better access to, and provision of, dental treatment systems. But it its misleading to use this study as “evidence ” against community water fluoridation.

Don’t believe everything you read on the web – especially on sites like Free Thought Project.com.

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2 Responses to “Yet another misrepresentation of a dental health study”

  • There are several confounding factors, vitamin D/skin colour being a possible one.
    In USA vitamin D supplementation of milk started in the 1930s, which helps somewhat, but who could afford or tolerate milk? Lactose intolerance is not even across racial types.
    Unless racial discrimination has been eliminated by when the study started it is possible that darker-skinned people won’t have had such good pay, so that confounds.

    People on average live a couple of years longer in UK than in USA, so they have more years to lose teeth.

    Wiki says 10% of UK citizens and 66% of USA citizens receive fluoridated water. If fluoridation helps the teeth of the poor it would be expected that poverty should not show so strongly as a factor.

    • Of course there are confounding factors, Brian. Oral health is influenced by a range of things. That is a reason why intercountry comparisons are difficult and should not be used to determine the role of any single factor. These are best determined within a country or region and with control or inclusion of other factors.

      An6ti-fluoide propagandist are well known for cherry-picking intercountry comparisons inappropriately to confirm their bias.

      If you read this paper (the full text was linked) you will see that it simply answered the question – are English teeth worse than US teeth. And for only one parameter. Their speculation on possible causes and lessons was just that – speculation.

      However, There is quite a bit of published work using properly designed studies which do show the influence of socio-economic and CWF as separate factors. So their speculation is worthwhile.

      Certainly, the anti-fluoride reporting of this is completely false.