Tag Archives: dental health

Anti-fluoridationists commonly misrepresent Ministry of Health data

Anti-fluoride activists tell porkies about the Ministry of Health’s data on child dental health. They cherry-pick the data to make it appear that community water fluoridation is ineffective. And when challenged to discuss the issue they run away.

I am currently dealing with family issues so am reposting this article, “A challenge to anti-fluoridationers to justify their misrepresentation of New Zealand research”  from April 2016.  It shows how local anti-fluoride activists are misrepresenting the Ministry of Health’s data on child oral health

One of the frustrations I have with the fluoridation issue is the refusal of anti-fluoride activists to engage on the science. They will pontificate, but they won’t engage in discussion.

On the surface, one would think there is a difference of opinion or interpretation of scientific issues and that could be resolved by discussion. Yet local anti-fluoride campaigners refuse to enter into discussion. Again and again, I have offered space here to local anti-fluoride campaigners so that they could respond to my articles and they have inevitably rejected the offer. They have also blocked me, and other people discussing the science, from commenting on any of their social media pages or web sites. Even when they, themselves, call for a debate they reject specific responses I have made accepting that call.

So I am left with the only alternative of responding to their claim with an article here – or on a friendly web or blog site. At least that gives me space to present my argument – I just wish I could get some intelligent responses enabling engagement on the issues.

Misrepresentations repeated

The latest misrepresentation of the science is a claim by the Auckland Fluoride Free NZ Coordinator, Kane Titchener, that recent research proves fluoridation [is] not needed.

It repeats the same misrepresentation made by Wellington Anti-fluoride campaigner, Stan Litras, which I discussed in my article Anti-fluoridation cherry-pickers at it again. Kane has either ignored my article, chosen to ignore it or possibly not even understood it.

So here we go again.

Kane claims:

“A New Zealand study published in Bio Medical Central Oral Health last month shows dental health improved the greatest extent for children in non-fluoridated areas. There is now no difference in dental decay rates between non-Maori children who live in fluoridated areas and non-Maori children who live in non-fluoridated areas, proving that fluoridation is not needed for children to obtain good dental health.”

Although he doesn’t cite the study (wonder why), his use of two figures from the study show he is writing about the paper:

Schluter, P. J., & Lee, M. (2016). Water fluoridation and ethnic inequities in dental caries profiles of New Zealand children aged 5 and 12–13 years: analysis of national cross-sectional registry databases for the decade 2004–2013. BMC Oral Health, 16(1), 21.

His claim relies on the comparison of data for “non-Māori” children in fluoridated and fluoridated areas. No – he doesn’t misrepresent the data – he just ignores the discussion by these authors of problems with simple interpretation of the data for non-Māori because of the fact it is not ethnically uniform. In particular, he ignores the qualifications they place on the data because of the inclusion in non-Māori of data for Pacifica who have poorer dental health than the rest of this group and live predominantly in fluoridated areas. This, in effect, distorts the data by overestimating the poor oral health for “non-Māori” in the fluoridated areas.

The apparent convergence

The data used in this study were taken from the Ministry of Health’s website. This divides the total population of children surveyed into the ethnic groups Māori, Pacific and “Other.” While the “other’ group will not be completely uniform (for example including Pakeha, Asian, other groups) it becomes far less uniform when combined with the Pacific group to form the non-Māori group.

So, Kane salivates over this figure from the paper especially the plots for  non-Māori ethnicities in fluoridated (F) and non-fluoridated (NF) areas.


Fig. 1 No obvious decay experience (caries-free) percentages and mean dmft for 5-year old children over years 2004 to 2013, partitioned by Māori and non-Māori ethnicities and fluoridated (F) and non-fluoridated (NF) areas

Yes, that convergence is clear and I can see why Kane is clinging to it – who can blame him. But he completely ignores the warning from the paper:

“It is likely that a substantial driver of this convergence was due to significant changes within the dynamic and heterogeneous non-Māori groups both within and between DHB regions. In effect, the ecological fallacy – a logical flaw whereby analyses of group data are used to draw conclusions about an individual – may be operating within the non-Māori group.”

When the Pacific data is removed (as is the case for the “other” group effectively made up from non-Māori and non-Pacifica) we get the plots below.


Comparison of data for “other” (non-Māori/non-Pacifica) children in fluoridated (F) and unfluoridated (UF) areas.

Nowhere near as useful for Kane’s confirmation bias and the message he wants to promote. OK – there is still some evidence of convergence from about 2007 on between fluoridated and unfluoridated children. But the graphs do show that community water fluoridation is still having  a beneficial effect. And this apparent convergence could be explained by things like the introduction of “hub and spoke” dental clinics after 2004. One problem with this raw data is that children are allocated according to the fluoridation status of the school – rather than their residence. This will lead to incorrect allocation in some cases.

Some data for Pacifica

Just to underline the problems introduced by inclusion of Pacific in the non-Māori group of the study consider the data for Pacifica shown below.


Data for 5-year-old children. dmft = decayed, missing and filled teeth. The “other” group is non-Māori and non-Pacifica

The oral health of Pacifica is clearly poorer than that of the “other” group.

Also, Pacifica make up about 20% of the non-Māori fluoridated group. So they will influence the data for the non-Māori fluoridated group by reducing the % caries free and increasing the mean dmft.

So Kane, like Stan, is blatantly cherry-picking. He is misrepresenting the study – and its author – by ignoring (or covering up) the qualifications regarding the influence of inclusion of pacific in the non-Māori fluoridated group.

The challenge

Now, I repeat the offer I have made in the past to give a right of reply to both Kane Titchener and Stan Litras. They are welcome to comment here and if they want more space I am happy to give space for separate articles for them in the way I did for the debate with Paul Connett. Now I can’t be fairer than that, can I?

So what about it Stan and Kane? What are your responses to my criticisms of the way you have cherry-picked and misrepresented this New Zealand paper?

NOTE: I have sent emails to both Kane and Stan asking them to respond and offering them right of reply.

UPDATE 1: Great minds and all that – Stan Litras sent out a press release today calling for a nation-wide debate on this issue (see FIND calls for a national debate on fluoridation). However, the seriousness of his request is rather compromised by his reply to my offer of a right of reply to the above article. He did respond to my email very quickly. This is what he wrote:

“Thanks for the offer, Ken, but I have not visited your blog site for a long time, as I object to the way you attempt to defame and discredit me.

You play the man and not the ball, which is not the mark of a reasonable person.

I hope to address that in due course as time permits, but for now I must leave you to indulge yourself without my company.”

So much for his wish for a “national debate” when he will not front up to a critique of his claims about the science.

UPDATE 2: Kane Titchener today also posted a press release today which was the text of the article I discuss in this post (see NZ research proves fluoridation not needed). He also responded quickly to my e-mail. The full text of his response was:

Who is this?”

Rather strange – considering he often pesters me with emails.

So I guess both of them have turned down my offer.

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Water fluoridation effective – new study

A recent Australian study shows community water fluoridation (CWF)  has a beneficial effect on oral health, even after taking into account the known effects of socioeconomic status and sugar consumption.

This is important because anti-fluoride propagandists are always pushing the mistaken claim that CWF is based only on “old science” and that “the science establishment” refuses to check these old findings. These propagandists have also latched onto the concern over the effects of excessive sugar consumption on general and oral health to claim that any apparent beneficial effect of CWF would disappear if sugar consumption was reduced.

The study is reported in:

Blinkhorn, A. S., Byun, R., Mehta, P., & Kay, M. (2015). A 4-year assessment of a new water-fluoridation scheme in New South Wales, Australia. International Dental Journal.

It  followed changes in the dental health of children in Gosford City, NSW, after introduction of CWF in 2008. It compared this with the oral health of children living in areas that had been fluoridated for over 40 years, and with those in the Shires of Ballina and Byron which were unfluoridated and had no plans to introduce CWF.

CWF clearly beneficial

The figure below compares the average numbers of decayed, missing and filled teeth (dmft) of 5-7 year-old children in 2008 (just before introduction of CWF to Gosford city – the “newly fluoridated area) with new batches of 5-7 year-old children in 2010 and 2012. In all three periods comparisons were made to similar children in the unfluoridated and long-term fluoridated areas.


Of course, anti-fluoridation activists might pick up on the improved oral health of children in unfluoridated areas in 2012 (and they might even try to ignore the rest of the data). But the clear message is that even though there may be a general improvement in oral health over time the children in the fluoridated areas still showed a clear benefit.

Influence of other factors

This study included measurement of other factors known to influence oral health. Statistical analysis of the data showed poorer dental health was significantly related to:

  • lower socioeconomic status;
  • origins (poorer dental health when mothers were born in a non-English speaking country;
  • lower educational level attained by parents, and
  • sugary drink consumption (poorer dental health where children consumed one or more drinks a day).

But, importantly, the statistical analysis showed a significant beneficial influence of CWF after taking these other factors into account. The following graph compares the dmft for newly fluoridated and unfluoridated areas relative to long-term fluoridated areas (defined as 1.0)


We can see that by 2012, 4 years after introduction of CWF, there is no significant difference between the oral health of children in the long-term and newly fluoridated areas. However, the oral health of children in the unfluoridated areas was significant poorer at all times.


Origins, socioeconomic status and consumption of sugary drinks have a statistically significant effect on children’s oral health. However, even when these are taken into account this research shows a clear beneficial effect of CWF on children’s dental health.

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