Fluoridation: Misrepresenting the “saliva theory”

I sometimes wonder if anti-fluoridation propagandists are trying to extend their “freedom of choice” argument to the scientific facts themselves. Perhaps this is how they justify to themselves their frequent cherry-picking and misrepresentation of research.

A current example is Fluoride Free NZ’s (FFNZ) misrepresentation of the mode of action of fluoride in protecting existing teeth in Saliva Theory Critique. Nothing new here – it’s a rehash of an older article of theirs which I critiqued 2 years ago in Fluoridation – topical confusion. But it still contains the same misinformation.

Selective quoting

Again FFNZ  misrepresents the advice of the Center For Disease Control (CDC) by selective quoting. Here is the relevant section of the document (CDC, 2001. Recommendations for Using Fluoride to Prevent and Control Dental Caries in the United States). The FFNZ article quoted only the 2 sentences in red!:

“Saliva is a major carrier of topical fluoride. The concentration of fluoride in ductal saliva, as it is secreted from salivary glands, is low — approximately 0.016 parts per million (ppm) in areas where drinking water is fluoridated and 0.006 ppm in nonfluoridated areas (27 ). This concentration of fluoride is not likely to affect cariogenic activity. However, drinking fluoridated water, brushing with fluoride toothpaste, or using other fluoride dental products can raise the concentration of fluoride in saliva present in the mouth 100-to 1,000-fold. The concentration returns to previous levels within 1–2 hours but, during this time, saliva serves as an important source of fluoride for concentration in plaque and for tooth remineralization (28 ).”

Their misrepresentation claims (in their words) “The CDC acknowledges that fluoridated water has no cariostatic effect” because of the low concentration of fluoride in secreted saliva. However, the full quote shows that the CDC advised that “saliva is a major carrier of topical fluoride” and that “drinking fluoridated water” is one way of increasing saliva fluoride concentration sufficiently so that “saliva serves as an important source of fluoride for concentration in plaque and for tooth remineralization.”

FFNZ purposely confuses the issue by ignoring the direct transfer of fluoride from water and food to saliva, dental plaque and biological tissue in the oral cavity. These act as reservoirs which can top-up the fluoride concentration at the tooth surface and help prevent demineralisation (responsible for tooth decay in acid conditions) and remineralisation.

“Topical” role of fluoride at tooth surface

This figure from the CDC document cited above provides a simple illustration of the way that fluoride, from fluoridated water, helps prevent tooth decay with existing teeth.

Even this shows that the mechanism is far from simple as the process is influenced by the concentration of phosphate and calcium in saliva, as well as fluoride. I would add that organic material, such as proteins, will also influence the mechanism. Then there is a process of transfer of fluoride, and other ions, to saliva from reservoirs like plaque, the tongue and other biological tissues which are known to store fluoride. For example, Vogel (2011) states:

“Current models for increasing the anti-caries effects of fluoride (F) agents emphasize the importance of maintaining a cariostatic concentration of F in oral fluids. The concentration of F in oral fluids is maintained by the release of this ion from bioavailable reservoirs on the teeth, oral mucosa and – most importantly, because of its association with the caries process – dental plaque.
Oral F reservoirs appear to be of two types: (1) mineral reservoirs, in particular calcium fluoride or phosphate contaminated ‘calcium-fluoride-like’ deposits; (2) biological reservoirs, in particular (with regard to dental plaque) F held to bacteria or bacterial fragments via calcium-fluoride bonds.”

Confusing the concentration issue

The FFNZ article attempts to confuse the issue again by citing 5 studies they claim “show that fluoridated water is too low in fluoride to provide any topical benefit.” But, of course, a more honest approach to the scientific literature is to consider all studies (not just the ones confirming one’s bias) and check relevant experimental details.

The studies they cite were not aimed at determining a minimum concentration for the surface reaction at the tooth surface. They were laboratory studies, using bovine dental material, usually not taking into account the role of other ions like calcium and phosphate. Several were studying fluoride/sucrose solutions.

In contrast, the review by Buzalaf (2011), Mechanisms of Action of Fluoride for
Caries Control  found:

“very low fluoride concentrations (sub- ppm range) in solution are already able to substantially inhibit acid dissolution of tooth minerals [23, 27].”

This was confirmed in the review of Ten Cate & Featherstone (1991). They cited studies showing inhibition of demineralisation at fluoride concentrations as low as 0.2 ppm and 0.025 ppm (Margolis et al., 1986). They also mention the higher fluoride concentrations required when ions like calcium and phosphate are omitted.

Demonstrated inhibition of demineralisation at such low fluoride concentration when the other relevant minerals are present does raise the possibility that fluoride in secreted saliva may still play a role, despite the view expressed in the CDC document cited above. However, let’s stress here, one does not have to take sides on that particular debate to recognise that the saliva fluoride concentration resulting from transfer from food and fluoridated water in the oral cavity is high enough to play a protective role against tooth decay. Bruun & Thylstrup (1984), who reported the low concentrations cited by the CDC, concluded that:

“direct contact of the oral cavity with F in the drinking water is the most likely source of the elevated whole saliva fluoride and that the increased availability of fluoride in the oral fluids has an important relationship to the reduced caries progression observed in fluoridated areas.”

So, again, the real world is not as simple as suggested by those who seek only to confirm their biases.

References

Bruun, C., & Thylstrup, A. (1984). Fluoride in Whole Saliva and Dental Caries Experience in Areas with High or Low Concentrations of Fluoride in the Drinking Water. Caries Research, 18(5), 450–456.

Buzalaf M.A.R., · Pessan J.P., · Honório H.M., & ten Cate J.M, (2011). Mechanisms of Action of Fluoride for Caries Control. In Buzalaf MAR (ed): Fluoride and the Oral Environment. Monogr Oral Sci. Basel, Karger, 2011, vol 22, pp 97–114

Center for Disease Control, 2001. Recommendations for Using Fluoride to Prevent and Control Dental Caries in the United States).

Margolis, H. C., Moreno, E. C., & Murphy, B. J. (1986). Effect of Low Levels of Fluoride in Solution on Enamel Demineralization in vitro. Journal of Dental Research, 65(1), 23–29.

Ten Cate, J. M.; Featherstone, J. D. B. (1991). Mechanistic Aspects of the Interactions Between Fluoride and Dental Enamel. Critical Reviews in Oral Biology and Medicine, 2(2), :283–296.

Vogel, G. L., (2011). Oral Fluoride Reservoirs and the Prevention of
Dental Caries. In Buzalaf MAR (ed): Fluoride and the Oral Environment.
Monogr Oral Sci. Basel, Karger, 2011, vol 22, pp 146–157

Similar articles

17 responses to “Fluoridation: Misrepresenting the “saliva theory”

  1. You can add as much fluoride as you like to your drinking water Ken but stop adding it to mine!!!

    Like

  2. chris price

    To drink it is your choice, you have alternatives, but getting one without any fluoride at all will be tricky and expensive

    Like

  3. Ken good scientists list their assumptions.

    If I am testing whether coarser shingle is better at preventing skidding the assumption is that that does not mean dumping the shingle on the road, but using it in construction with the right amount of tar.

    But the way the fluoride issue seems to be approached is some of the testers may dump it on the road and others may adhere it, and we should only look at the average.

    Like

  4. What a silly comment, Brian. In this article I have commented on the fact that the FFNZ people cherry-picked laboratory studies which didn’t replicate the situation existing at the tooth surface in terms of the other ions inofuenicng apatites solubility. Whereas, the reviews I cited did include studies which included other minerals.

    Nothing to do with roads, tar or gravel.

    By the way, I have put you in moderation and will stop comments like your last one which was simply aimed at baiting someone who hadn’t even commented. It was provocative, not serious.

    Like

  5. In attempting to make an issue of the topical versus systemic effect, antifluoridationists fail to understand that it is a moot point. Public health initiatives are measured by their effects on entire populations, not on individual mechanisms. Water fluoridation has been demonstrated in countless peer-reviewed studies to reduce dental decay in entire populations. It makes not one bit of difference whether this reduction is due to topical or systemic actions of fluoride, or to such things as raising awareness of the importance of proper oral hygiene. It works, causes no adverse effects, and, at a cost of less than $1 per person per year, is by far the most cost-effective means of dental decay prevention available.

    That said, however, antifluoridationists cannot even make their argument even if the exact mechanism of fluoridation did make a difference. The most glaring conflict in their argument is the mild to very mild dental fluorosis which they constantly, and dishonestly attempt to portray as some major life-threatening disorder. Mild to very mild is the only dental fluorosis which may be attributable to optimally fluoridated water.  This level of dental fluorosis is a barely detectable effect which causes no adverse effect on cosmetics, form, function, or health of teeth.  As Kumar, et al. have demonstrated mildly fluorosed teeth to be more decay resistant, a definite benefit, many consider this effect to not even be undesirable, much less adverse.  Dental fluorosis can only occur systemically. 

    —-The Association Between Enamel Fluorosis and Dental Caries in U.S. Schoolchildren Hiroko Iida, DDS, MPH and Jayanth V. Kumar, DDS, MPH
    http://jada.ada.org/content/140/7/855.long

    Additionally, a 2014 study, Cho, et al. found:

    “Conclusions: While 6-year-old children who had not ingested fluoridated water showed higher dft in theWF-ceased area than in the non-WF area, 11-year-old children in theWF-ceased area who had ingested fluoridated water for approximately 4 years after birth showed significantly lower DMFT
    than those in the non-WF area. This suggests that the systemic effect of fluoride intake through water fluoridation could be important for the prevention of dental caries.”

    —Systemic effect of water fluoridation on dental caries prevalence
    Cho HJ, Jin BH, Park DY, Jung SH, Lee HS, Paik DI, Bae KH.
    Community Dent Oral Epidemiol 2014; 42: 341–348. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd

    Steven D. Slott, DDS

    Like

  6. I read that about Ritchie not being allowed to sell his remineralizing mix in shops in an article about residents in an old Dunedin Education building. However I had bought Dentamin in the 1970s in several shops in Christchurch. I learned of him through the package label. I am wondering why it was stopped. You could have read the ingredient mix on a recent post of mine, the Sauerheber article with long posts.

    Like

  7. A poor case for fluoridation
    June 13,2015
    Dr. Peter Mansfield of England summarized the ethical case against public water fluoridation about as well as anyone could. He said: “No physician in his right senses would prescribe for a person he has never met, whose medical history he does not know, a substance which is intended to create bodily change, with the advice, ‘Take as much as you like, but you will take it for the rest of your life because some children suffer from tooth decay.’”
    Mansfield took part in the University of York (in York, England) review of public water fluoridation in 2000.
    JACK CROWTHER

    Like

  8. Summary of the ethical case against public water fluoridation?

    includes the definition a substance which is intended to create bodily change

    I guess that rules out food then.

    Let’s test the statement.

    “No physician in his right senses would prescribe for a person he has never met, whose medical history he does not know, a substance which is intended to create bodily change, with the advice, ‘Take as much as you like, but you will take it for the rest of your life because some children suffer from starvation.’”

    Yep. That rules out food.

    You have to laugh at the strength of some of the arguments brought against public water fluoridation.

    They’re good enough for Trevor though.

    Like

  9. Trev, I notice that Peter Mansfield was actually not an author of the York review as you claim. The authors (or Review Team)were:

    Jos Kleijnen, NHS Centre for Reviews and Dissemination, York, UK

    Marian McDonagh, NHS Centre for Reviews and Dissemination, York, UK

    Kate Misso, NHS Centre for Reviews and Dissemination, York, UK

    Penny Whiting, NHS Centre for Reviews and Dissemination, York, UK

    Paul Wilson, NHS Centre for Reviews and Dissemination, York, UK

    Ivor Chestnutt, Dental Public Health Unit, Cardiff, Wales, UK

    Jan Cooper, Dental School, University of Wales College of Medicine, Cardiff, Wales, UK

    Elizabeth Treasure, Dental School, University of Wales College of Medicine, Cardiff, Wales, UK

    >

    Like

  10. And who the hell is JACK CROWTHER?

    You have been indulging in copy and paste from social media again, haven’t you Trev?🙂

    Why not deal with the subject of this article – it doesn’t exactly put your organisation FFNZ in a good light, does it Trev? >

    Like

  11. Fact and source checking are not Trevor’s strong points.

    Like

  12. And here is the “Letter to the Editor” Trev has copied. A poor case for fluoridation

    Like

  13. How many times has Trevor pasted material without attribution?
    It must be close to, or over, a dozen times, possibly much more, in fact, just about every time he quotes something he fails to provide citation. Worse, he doesn’t even alert to the fact that the material pasted is someone else’s effort.

    That’s called plagiarism. An ugly practise.

    He has been asked, on at least five occasions, to desist from doing so, to instead always provide citation.

    Poor Trevor.

    Like

  14. chris price

    That Mansfield piece came up in a paper comment today ,and I looked at my copy of the York review and could not find his name,,I wonder what the connection it, looks suspicious, but then this is standard procedure for the anti fluoride/vaccine lot

    Like

  15. Manfield was on the Advisory Committee – which included both pro and anti, as well as neutral, fluoridation representatives. They were not authors and did not all agree with the review report. I gather Manfield was a GP with alternative tendencies.

    It is one of a list of quotes the anti-fluoridation propagandists use but never bother checking. So they often imply he was one of the authours of the review – he wasn’t.

    They do a similar thing with Professor Trevor Sheldon who was also not an author but on the advisory committee.

    Very dishonest.

    Like

  16. Heh, I expect Mr Deal will delete that comment.
    He’s a sneaky s.o.b. He once took comments from this blog, wrote a whole post misrepresenting the comments but didn’t alert the authors here to it. Besides being grossly discourteous, it illustrates that he doesn’t offer the right of reply and doesn’t risk open debate.

    Like

Leave a Reply: please be polite to other commenters & no ad hominems.

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s