10 ms·

Water Fluoridation May Not Prevent Cavities, Scientific Review Shows

130 points by rl3 11y ago

ForEnglandJames 11y ago
So it really was just for mind control... :3
tokenadult 11y ago
As the article notes, this is all based on the Cochrane Collaborative methodology of searching for prior published scientific literature, and is not a conclusion based on a fresh study. The article also points out, "Another 2009 review[link] by the Cochrane group clearly shows that fluoride toothpaste prevents cavities, serving as a useful counterpoint to fluoridation’s uncertain benefits." [link] http://www.cochrane.org/CD002278/ORAL_fluoride-toothpastes-for-preventing-dental-caries-in-children-and-adolescents http://www.cochrane.org/CD002278/ORAL_fluoride-toothpastes-f... "Tooth decay (dental caries) is painful, expensive to treat and can sometimes lead to serious damage to teeth. Fluoride is a mineral that prevents tooth decay. The review of trials found that children aged 5 to 16 years who used a fluoridated toothpaste had fewer decayed, missing and filled permanent teeth after three years (regardless of whether their drinking water was fluoridated). Twice a day use increases the benefit."
- jessriedel 11y ago
  A new Cochrane meta-analysis is much more likely to make me change my mind about some empirical claim than a fresh study.
  - tokenadult 11y ago
    On the whole, the Cochrane Collaboration is a force for good, but its methodology of reviewing previous published studies lets it miss important issues of prior plausibility (that is, lack of plausibility) when reviewing "alternative" treatments. https://www.sciencebasedmedicine.org/of-sbm-and-ebm-redux-part-iv-continued-more-cochrane-and-a-little-bayes/ https://www.sciencebasedmedicine.org/of-sbm-and-ebm-redux-pa...
    - jameshart 11y ago
      Was that conclusion the result of a meta-analysis of meta-analysis methodologies? And there I thought this was just an amusing cartoon... https://xkcd.com/1447/ https://xkcd.com/1447/
    - jessriedel 11y ago
      I don't think this has anything to do with Cochrane's methodology. This is about choice of presentation. They are very clear in the paper that they are reviewing a certain body of studies, and that there are other plausible reasons (not backed up by RCTs) to believe water fluoridation could have beneficial effects. The numbers they quote summarize the evidential content of the RCTs. I don't need or want them to bundle this all into one Bayesian percentage. This would be dominated by their own priors which I do not necessary share nor are necessary shared by anyone I discuss the study with. (Yet we can all agree on the frequentist summary of the RCTs.)
- jmckib 11y ago
  > The article also points out, "Another 2009 review[link] by the Cochrane group clearly shows that fluoride toothpaste prevents cavities, serving as a useful counterpoint to fluoridation’s uncertain benefits." I think you understood this, but I wanted to clarify for others: the Cochrane review that this article is about showed that fluoridated water may not prevent tooth decay. The 2009 review you mention does not contradict this, since it is about fluoridated toothpaste, not water.
  - xherberta 11y ago
    There's another relevant Cochrane review that compares the effect of multiple topical fluoride therapies vs. a single therapy (i.e. toothpaste.) http://onlinelibrary.wiley.com/doi/10.1002/14651858.CD002781.pub2/abstract http://onlinelibrary.wiley.com/doi/10.1002/14651858.CD002781... "The separate meta-analyses of fluoride gel or mouthrinse combined with toothpaste versus toothpaste alone favour the combined regimens, but differences were not statistically significant; the significant difference in favour of the combined use of fluoride varnish and toothpaste accrues from a very small trial and appears likely to be a spurious result. [Except for two studies finding gel + mouthrinse to be more effective than gel alone,] no other combinations of topical fluoride therapy were consistently superior to a single therapy." Since fluoride can harm brains, kidneys, and more at certain doses, I'm glad people are interested in which therapies are most effective and are seeking the optimal exposure level.
- deleted 11y ago
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deleted 11y ago
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colordrops 11y ago
Harvard study finding fluoride in water does negatively impact childhood development: http://www.hsph.harvard.edu/news/features/fluoride-childrens-health-grandjean-choi/ http://www.hsph.harvard.edu/news/features/fluoride-childrens...
- jarin 11y ago
  It should be noted that the negative effects were found in areas with much higher levels of fluoridation (i.e. areas of China with naturally occurring fluoride in groundwater) than are typical in the US. There wasn't enough information to draw conclusions about US fluoridation levels.
  - colordrops 11y ago
    The limit for fluoride in US drinking water is 4.0 mg/L, and there are regions in the paper that report cognitive impairment that are much lower than this. You should consider posting analysis or sources for your statements, or just not comment and let the paper speak for itself.
- mikeyouse 11y ago
  It's important to note that this study was performed in China where they don't intentionally fluoridate their water supply. There are many areas with natural (or industrial waste..) levels of fluoride and many of these areas far exceed the level recommended for use in the US. The current target concentration in the US is 0.7mg/L and is routinely monitored and lowered if the background level is too high where some of the 'hot spots' in China that saw childhood development issues had water containing above 6mg/L and one area had a range from 118mg/kg to 1,361mg/kg (thank you coal mining). Another confounding factor is that many of the areas with high fluoride levels also had high aluminum, mercury, and arsenic levels as well. I'd like to see a study comparing IQs or development with actual usage levels and without the heavy metal pollutants from industry. Full HSPH study: http://ehp.niehs.nih.gov/wp-content/uploads/2012/09/ehp.1104912.pdf http://ehp.niehs.nih.gov/wp-content/uploads/2012/09/ehp.1104...
  - 11y ago
NoMoreNicksLeft 11y ago
Did anyone expect it to do so? Fluorine production was a proxy for uranium production if the only use for fluorine was for uranium production. Couldn't have the Soviets knowing how many atom bombs we were building, so we needed to use it for something else too. Something so massive that it would make it impossible to calculate how much was used for nukes. And so we put it in the water supply as an additive.
- ColinDabritz 11y ago
  Interesting, do you have a citation for this one? It reminds me of the "carrots help you see better" myth that began as WWII propaganda [1] as a cover for radar and has been very persistent since. [1] http://www.washingtonpost.com/news/speaking-of-science/wp/2014/12/15/no-carrots-dont-make-your-eyesight-better/ http://www.washingtonpost.com/news/speaking-of-science/wp/20...
- happyscrappy 11y ago
  Mandrake, have you ever seen a commie drink a glass of water?
  - stcredzero 11y ago
    "Purity of Essence"
- vonmoltke 11y ago
  Huh? Fluorine's oldest and most common industrial use is in steelmaking. It is also used heavily in refrigerants.
- x5n1 11y ago
  According to the Fluorine Deception, they needed a way to get rid of the effluent so they made it a health product rather than toxic waste. That book however has been dismissed by most supporters of fluoridation as written by a nutbar. http://www.amazon.com/The-Fluoride-Deception-Christopher-Bryson/dp/1583227008 http://www.amazon.com/The-Fluoride-Deception-Christopher-Bry... "Concerns over fluoridated drinking water have long been derided as the obsession of McCarthyite cranks. But this muckraking j’accuse asserts that fluoride is indeed a dire threat to public health, one foisted upon the nation by a vast conspiracy—not of Communist agents, but of our very own military-industrial complex. Investigative reporter Bryson revisits the decades-long controversy, drawing on mountains of scientific studies, some unearthed from secret archives of government and corporate laboratories, to question the effects of fluoride and the motives of its leading advocates. The efficacy of fluoridated drinking water in preventing tooth decay, he contends, is dubious. Fluoride in its many forms may be one of the most toxic of industrial pollutants, and Bryson cites scientific analyses linking fluoridated drinking water to bone deformities, hyperactivity and a host of other complaints. The post-war campaign to fluoridate drinking water, he claims, was less a public health innovation than a public relations ploy sponsored by industrial users of fluoride—including the government’s nuclear weapons program. Legendary spin doctors like Edward Bernays exploited the tenuous link between dental hygiene and fluoridation to create markets to stimulate fluoride production and to prove the innocuousness of fluoride compounds, thereby heading off lawsuits by factory workers and others poisoned by industrial fluoride pollution. Bryson marshals an impressive amount of research to demonstrate fluoride’s harmfulness, the ties between leading fluoride researchers and the corporations who funded and benefited from their research, and what he says is the duplicity with which fluoridation was sold to the people. The result is a compelling challenge to the reigning dental orthodoxy, which should provoke renewed scientific scrutiny and public debate."
jessriedel 11y ago
Just so everyone is clear: this review found that there is little evidence that water fluoridation has any benefits. It does not dispute that fluoride in toothpaste reduces tooth decay. > Studies that attest to the effectiveness of fluoridation were generally done before the widespread usage of fluoride-containing dental products like rinses and toothpastes in the 1970s and later, according to the recent Cochrane study. So while it may have once made sense to add fluoride to water, it no longer appears to be necessary or useful, Thiessen says. > It has also become clear in the last 15 years that fluoride primarily acts topically, according to the CDC. It reacts with the surface of the tooth enamel, making it more resistant to acids excreted by bacteria. Thus, there's no good reason to swallow fluoride and subject every tissue of your body to it, Thiessen says. > Another 2009 review by the Cochrane group clearly shows that fluoride toothpaste prevents cavities.
- mikeyouse 11y ago
  The theory I've encountered is that fluoridation previously had an impact on cavity-prevention before people were actually brushing their teeth with fluoridated toothpaste. Now that toothbrushing is much more common, the impact has waned. Late edit; Here's a look at toothbrushing frequency in Europe by country from 1994 - 2010: http://i.imgur.com/VVBldAy.jpg http://i.imgur.com/VVBldAy.jpg Just imagine how much improvement you'd see from if the chart started in the 1940's and 1950's when many cities began fluoridating their water supplies. Not to mention that many early toothpastes were often ineffective at preventing cavities by primarily relying on baking soda and peroxide. (Full brushing frequency study: http://eurpub.oxfordjournals.org/content/25/suppl_2/20 http://eurpub.oxfordjournals.org/content/25/suppl_2/20 )
  - gcb0 11y ago
    remember that non controlled measurements are worthless. same time they started water fluoridation the population also started to pay attention to brushing their teeth. or do you think the govt took the initiative at any point in history?
- scott_s 11y ago
  Unfortunately, it's not accurate to say there is no evidence. There is evidence, it's just old evidence. For some reason, Newsweek decided to focus on the fact that there is no evidence that fluoridation is helpful for adults, and that the evidence for children is almost all from before 1975. That is important since behaviors may have changed post-1975. The "Plain language summary" from the authors - their words, so this is the authors of the study synthesizing their conclusions for a lay audience - is clear: Data suggest that the introduction of water fluoridation resulted in a 35% reduction in decayed, missing or filled baby teeth and a 26% reduction in decayed, missing or filled permanent teeth. It also increased the percentage of children with no decay by 15%. Although these results indicate that water fluoridation is effective at reducing levels of tooth decay in children's baby and permanent teeth, the applicability of the results to current lifestyles is unclear because the majority of the studies were conducted before fluoride toothpastes and the other preventative meaures were widely used in many communities around the world. There was insufficient information available to find out whether the introduction of a water fluoridation programme changed existing differences in tooth decay across socioeconomic groups. There was insufficient information available to understand the effect of stopping water fluoridation programmes on tooth decay. No studies met the review’s inclusion criteria that investigated the effectiveness of water fluoridation for preventing tooth decay in adults, rather than children. This is from http://onlinelibrary.wiley.com/doi/10.1002/14651858.CD010856.pub2/abstract http://onlinelibrary.wiley.com/doi/10.1002/14651858.CD010856.... Thanks to HN user giarc (https://news.ycombinator.com/item?id=9807427 https://news.ycombinator.com/item?id=9807427) for pointing it out.
godgod 11y ago
And yet municipalities put it in our water. I feel poisoned drinking tap water.
fapjacks 11y ago
Oh, so then that means that fluoride is actually for mind control. Gotcha.
- fapjacks 11y ago
  I see the sarcasm was completely lost on at least four geniuses.
  - biot 11y ago
    Fortunately for the quality of this site, there were only a few people who lacked the self-restraint needed to avoid pointing out such a painfully obvious, reddit-esque joke.
    - fapjacks 11y ago
      >quality I take it you're new here. HN has been "tech reddit" for at least a couple of years now. (This will probably whoosh miles overhead, too).
ChaoticGood 11y ago
It is a great idea to revisit public policies that were put into place at the same time Doctors were advertising Cigarettes as healthy. Water is a precious resource and should be protected as such. "Generally, in Germany fluoridation of drinking water is forbidden. The relevant German law allows exceptions to the fluoridation ban on application. The argumentation of the Federal Ministry of Health against a general permission of fluoridation of drinking water is the problematic nature of compuls[ory] medication." (Gerda Hankel-Khan, Embassy of Federal Republic of Germany, September 16, 1999).[0] Germany halted its water fluoridation in the 1970s and France never started.[1] [0] http://www.slweb.org/50reasons.html http://www.slweb.org/50reasons.html [1] http://www.theguardian.com/world/2013/sep/17/water-fluoridation http://www.theguardian.com/world/2013/sep/17/water-fluoridat...
- dd9990 11y ago
  Fluoridation has been mandatory in Ireland since the 50s. Considering how radically Irish lifestyles have changed in the last few decades (less poverty, better access to dental products, inexpensive/free dental care etc) I think it's crazy we're still forcefully mass medicating the majority of the population without their consent. Although mostly harmless, excessive fluoridation was recently linked to hypothyroidism in a UK study. I think it's time to seriously reconsider the decision instead of the occasional self-assurance everything is fine as is.
- _delirium 11y ago
  Generally Europe doesn't fluoridate its water, true, but the practical effect is a bit more nuanced. For example, Germany has mostly moved its fluoridation program from water to salt: http://www.ncbi.nlm.nih.gov/pubmed/16156167 http://www.ncbi.nlm.nih.gov/pubmed/16156167 In Denmark the water isn't fluoridated, but its natural levels of fluoride are only slightly lower than the levels that U.S. cities add (for example in the Copenhagen water supply, fluoride is around 0.6 mg/L). So it's a bit pedantic to claim that it isn't fluoridated. It's true that the utility company is not adding more fluoride to the water, but the end result is still that the pipes are delivering tap water with fluoride in it.
nsxwolf 11y ago
Here comes all the kids with rotten teeth and measles.
evunveot 11y ago
From what I've read, we've already identified the specific bacteria responsible for tooth decay [1], but there seems to have no interest in developing treatments based on that insight. Instead we're supposed to essentially sterilize our mouths and remineralize our teeth (which is something saliva does naturally) with topical fluoride twice a day. My cat has never brushed her teeth, and they're fine, presumably because the microbiome in her mouth is in a state where bacteria that secrete lactic acid are crowded out by benign species. Granted, she doesn't eat many simple sugars, but I have had a vet recommend brushing her teeth twice a day as a preventative measure, which blew my mind. I hope I live to see the day when the extent of oral hygiene maintenance and bad breath prevention is a toothpick and an occasional probiotic mouthwash or something. [1] https://en.wikipedia.org/wiki/Dental_caries#Bacteria https://en.wikipedia.org/wiki/Dental_caries#Bacteria
- giarc 11y ago
  This made the news awhile ago, it's called STAMP (specifically targeted antimicrobial peptides). Here's a 2011 article that seems to show some progress. http://www.ncbi.nlm.nih.gov/pubmed/21860239 http://www.ncbi.nlm.nih.gov/pubmed/21860239
  - mrfusion 11y ago
    Wow, sounds promising. Is that something you can buy?
  - knodi123 11y ago
    Evora will be glad to sell you probiotic lozenges containing benign mouth bacteria that can outcompete the harmful ones. Personally, I used them for two months as directed, and saw no real difference. Can't wait for a real product, I just hope it doesn't start off costing $200/month like some probiotics I've seen.
    - jws 11y ago
      Curious: How would you observe a difference in two months? (HN being what it is, I'm half expecting you to tell me you were assaying your mouth bacteria with an electron microscope you made and some OpenCV hacked together on…)
giarc 11y ago
Can we change the link to the actual Cochrane review which does provide a plain language interpretation of the results? http://onlinelibrary.wiley.com/doi/10.1002/14651858.CD010856.pub2/abstract http://onlinelibrary.wiley.com/doi/10.1002/14651858.CD010856...
- jmckib 11y ago
  Here's an anchor link directly to the plan language summary. http://onlinelibrary.wiley.com/doi/10.1002/14651858.CD010856.pub2/abstract#shortAbstract http://onlinelibrary.wiley.com/doi/10.1002/14651858.CD010856...
- dang 11y ago
  The Newsweek article contains considerable additional reporting, and does not appear (at first glance) to distort what the Cochrane review says. Unless that's wrong, I don't think we need to swap the URL.
cvwright 11y ago
They don't fluoridate the water here in Portland, OR. Compared to other parts of the country where I've lived, the difference in people's teeth is pretty shocking. I haven't heard any alternative hypothesis that would explain this difference better than the lack of fluoridation here. As I understand the article, they're saying that they couldn't find rigorous studies demonstrating the beneficial effects of fluoride. They don't claim there's any evidence against fluoride having beneficial effects, just that the studies haven't been done.
- stephengillie 11y ago
  There's too much inertia in favor of fluoride being beneficial for any serious researcher to risk their credibility. Everyone "knows" fluoride makes teeth stronger, like lettuce being healthy to eat, or global warming is human-caused. In fact, even discussing the possibility is too much for most people to entertain. They think you're wasting their time with fantasy and falsehood, like conspiracy theorists always do. Fluoride being bad for teeth is as believable as airliners dropping chemtrails everywhere, or jet fuel not "spheroiding" steel after hours of heating.
  - stephengillie 11y ago
    See? Even posting about the idea of researching it merits a downvote. The idea that fluoride has no benefits is as popular as Apple and Microsoft merging.
- pavedwalden 11y ago
  With over half of people currently in the Portland metro area having been born elsewhere, it would be hard to sort out whether cavities were the result of fluoride deficiency or some sort of selection bias in who chooses to live there. I never noticed a lot of fillings when I lived in Portland, but then I wasn't looking inside people's mouths.
- fnordfnordfnord 11y ago
  How many dentists per capita are there in Portland compared to similar cities. Edit, I checked. It seems that it might be higher than average.
cromulent 11y ago
Correlation. Everyone should get the right amount of fluoride. This is actually quite difficult to measure and achieve. WHO seem to have a good viewpoint: "The effects of fluoride are best predicted by the dose (i.e. mg fluoride per kg of body weight per day), the duration of exposure and other factors such as age (e.g. dental fluorosis). However, most epidemiological studies concerning the effects of fluoride on teeth and bone have correlated the effects with the concentration of fluoride in the drinking-water (mg l–1 fluoride) consumed rather than total fluoride exposure. ... Perhaps the best general advice that can be given in relation to local conditions is that, at a minimum, the fluoride level in local water supplies should be monitored and the population examined for signs of excessive fluoride exposure (e.g. moderate and/or severe dental fluorosis and crippling skeletal fluorosis). Where treatment to remove fluoride is practised, chemicals used should be of a grade suitable for use in drinking-water supply as outlined in the WHO Guidelines for Drinking-water Quality." http://www.who.int/water_sanitation_health/publications/fluoride_drinking_water_full.pdf?ua=1 http://www.who.int/water_sanitation_health/publications/fluo...
jug5 11y ago
Keep drinking that fluoride folks. Enjoy the flavor.
jrcii 11y ago
I can no longer sit back and allow Communist infiltration, Communist indoctrination, Communist subversion and the international Communist conspiracy to sap and impurify all of our precious bodily fluids.
- jjulius 11y ago
  Mandrake, have you ever seen a Commie drink a glass of water?
  - vbnmvbnmvbnm 11y ago
    Ice cream, Mandrake? Children's ice cream?
JeremyNT 11y ago
This article has such a bad headline. The important thing to note here is that this review is looking for the impacts of fluoridation since the 1970s. The evidence remains clear that fluoridation is better than nothing at preventing cavities! The question at hand is whether it's still important now that we have widespread adoption of fluoride toothpaste. This Cochrane study concludes, as many Cochrane reviews do, that there's not yet enough high quality evidence to answer this question. The takeaway here shouldn't be the absurd headline that "fluoridation may not prevent cavities," it should be "we should study how effective fluoridation is now that we have added other successful interventions."
- SuddsMcDuff 11y ago
  The headline introduces an element of doubt in something that was previously reckoned to be conclusive. I'd say it's pretty effective.
lutorm 11y ago
Having grown up in Sweden, being told that fluoride applied topically was functional at reducing caries but that eating toothpaste or swallowing the fluoride rinse that we got in elementary school was bad for you, I was astonished to learn that some countries put it in their water. Even in the U.S., toothpaste containers warn you not to swallow it and contact a Poison Control Center if you accidentally do. And then they put it in tap water? It just seems really inconsistent.
- aggie 11y ago
  Just a guess but those cases are probably due to the fluoride concentration of the rinse and toothpaste. Things that can be beneficial at small doses can be harmful in larger doses.
- sliverstorm 11y ago
  I suspect that the "don't eat toothpaste" stuff is mostly overblown and primarily just to ensure kids don't eat toothpaste like candy (which kids will do). In large quantities (say, a whole tube) it will make you throw up, and maybe you could accumulate too much flouride. Is a pea-sized drop on your toothbrush going to hurt you if you swallow it, no, but there's no reason to swallow toothpaste and a number of mild reasons why you probably shouldn't.
- snowwrestler 11y ago
  The actual warning is: > Keep out of reach of children under 6 years of age. If more than used for brushing is accidentally swallowed, get medical help or contact a Poison Control Center right away. Note: more than used for brushing So, it's fine to swallow your toothpaste if you want. But if your 4 year swallows a whole tube of it, they are probably going to get sick to their stomach.
- DanBC 11y ago
  Toothpaste has lots of fluoride in, because it's a topical treatment. Eating the toothpaste risks "fluorosis" - discoloured teeth. https://en.wikipedia.org/wiki/Dental_fluorosis https://en.wikipedia.org/wiki/Dental_fluorosis
- 11y ago
marze 11y ago
My policy: if someone wants me to eat poison, even if in small doses, there better be some really bulletproof evidence of benefit.
ownedthx 11y ago
Since there are US cities like Texarkana, AR that have not have fluoride in the water ever, it seems they would be a decent way to harvest some data quickly and get to the bottom of this. Anecdotally, I know a dentist that would work 2 days a week there as a sort of 'import-a-dentist' program, and she thought teeth were, in general, in much worse shape there than Little Rock, AR (3 hours away). Not enough to go on obviously.
- facetube 11y ago
  Portland, Oregon doesn't have any fluoride in its water supply either, for what it's worth.
  - ownedthx 11y ago
    Seemingly a good list; http://fluoridealert.org/content/communities/ http://fluoridealert.org/content/communities/
- stephengillie 11y ago
  While there's lots of anecdotal evidence trying to correlate these ideas, supposedly the statistical correlation isn't there.
SQL2219 11y ago
yea well, it reduces IQ, so we're keeping it. http://www.hsph.harvard.edu/news/features/fluoride-childrens-health-grandjean-choi/ http://www.hsph.harvard.edu/news/features/fluoride-childrens...
jane_is_here 11y ago
Yet another excellent reason to not get your scientific information from the popular media.
BuckRogers 11y ago
Wasn't this obvious the whole time? You don't need a study to show that drinking fluoridated water doesn't help your teeth. Fluoride is applied topically.
gtrubetskoy 11y ago
An educational video from Univ. of Nottingham, if you don't know how nasty (and fun) Fluorine is: https://www.youtube.com/watch?v=vtWp45Eewtw https://www.youtube.com/watch?v=vtWp45Eewtw (and they explain the tooth enamel theory towards the end as well).
nixy 11y ago
Methods to prevent tooth decay were investigated and documented in Sweden back in the 30's and 40's. Studies were carried out at a mental hospital where patients were force fed sugary sweets to provoke caries. I believe fluoridation was one of the things found to help prevent caries. https://en.wikipedia.org/wiki/Vipeholm_experiments https://en.wikipedia.org/wiki/Vipeholm_experiments

130 points by rl3 11y ago

So it really was just for mind control... :3

As the article notes, this is all based on the Cochrane Collaborative methodology of searching for prior published scientific literature, and is not a conclusion based on a fresh study. The article also points out, "Another 2009 review[link] by the Cochrane group clearly shows that fluoride toothpaste prevents cavities, serving as a useful counterpoint to fluoridation’s uncertain benefits." [link] http://www.cochrane.org/CD002278/ORAL_fluoride-toothpastes-for-preventing-dental-caries-in-children-and-adolescents http://www.cochrane.org/CD002278/ORAL_fluoride-toothpastes-f... "Tooth decay (dental caries) is painful, expensive to treat and can sometimes lead to serious damage to teeth. Fluoride is a mineral that prevents tooth decay. The review of trials found that children aged 5 to 16 years who used a fluoridated toothpaste had fewer decayed, missing and filled permanent teeth after three years (regardless of whether their drinking water was fluoridated). Twice a day use increases the benefit."

jessriedel 11y ago
A new Cochrane meta-analysis is much more likely to make me change my mind about some empirical claim than a fresh study.
- tokenadult 11y ago
  On the whole, the Cochrane Collaboration is a force for good, but its methodology of reviewing previous published studies lets it miss important issues of prior plausibility (that is, lack of plausibility) when reviewing "alternative" treatments. https://www.sciencebasedmedicine.org/of-sbm-and-ebm-redux-part-iv-continued-more-cochrane-and-a-little-bayes/ https://www.sciencebasedmedicine.org/of-sbm-and-ebm-redux-pa...
  - jameshart 11y ago
    Was that conclusion the result of a meta-analysis of meta-analysis methodologies? And there I thought this was just an amusing cartoon... https://xkcd.com/1447/ https://xkcd.com/1447/
  - jessriedel 11y ago
    I don't think this has anything to do with Cochrane's methodology. This is about choice of presentation. They are very clear in the paper that they are reviewing a certain body of studies, and that there are other plausible reasons (not backed up by RCTs) to believe water fluoridation could have beneficial effects. The numbers they quote summarize the evidential content of the RCTs. I don't need or want them to bundle this all into one Bayesian percentage. This would be dominated by their own priors which I do not necessary share nor are necessary shared by anyone I discuss the study with. (Yet we can all agree on the frequentist summary of the RCTs.)
jmckib 11y ago
> The article also points out, "Another 2009 review[link] by the Cochrane group clearly shows that fluoride toothpaste prevents cavities, serving as a useful counterpoint to fluoridation’s uncertain benefits." I think you understood this, but I wanted to clarify for others: the Cochrane review that this article is about showed that fluoridated water may not prevent tooth decay. The 2009 review you mention does not contradict this, since it is about fluoridated toothpaste, not water.
- xherberta 11y ago
  There's another relevant Cochrane review that compares the effect of multiple topical fluoride therapies vs. a single therapy (i.e. toothpaste.) http://onlinelibrary.wiley.com/doi/10.1002/14651858.CD002781.pub2/abstract http://onlinelibrary.wiley.com/doi/10.1002/14651858.CD002781... "The separate meta-analyses of fluoride gel or mouthrinse combined with toothpaste versus toothpaste alone favour the combined regimens, but differences were not statistically significant; the significant difference in favour of the combined use of fluoride varnish and toothpaste accrues from a very small trial and appears likely to be a spurious result. [Except for two studies finding gel + mouthrinse to be more effective than gel alone,] no other combinations of topical fluoride therapy were consistently superior to a single therapy." Since fluoride can harm brains, kidneys, and more at certain doses, I'm glad people are interested in which therapies are most effective and are seeking the optimal exposure level.
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colordrops 11y ago

Harvard study finding fluoride in water does negatively impact childhood development: http://www.hsph.harvard.edu/news/features/fluoride-childrens-health-grandjean-choi/ http://www.hsph.harvard.edu/news/features/fluoride-childrens...

jarin 11y ago
It should be noted that the negative effects were found in areas with much higher levels of fluoridation (i.e. areas of China with naturally occurring fluoride in groundwater) than are typical in the US. There wasn't enough information to draw conclusions about US fluoridation levels.
- colordrops 11y ago
  The limit for fluoride in US drinking water is 4.0 mg/L, and there are regions in the paper that report cognitive impairment that are much lower than this. You should consider posting analysis or sources for your statements, or just not comment and let the paper speak for itself.
mikeyouse 11y ago
It's important to note that this study was performed in China where they don't intentionally fluoridate their water supply. There are many areas with natural (or industrial waste..) levels of fluoride and many of these areas far exceed the level recommended for use in the US. The current target concentration in the US is 0.7mg/L and is routinely monitored and lowered if the background level is too high where some of the 'hot spots' in China that saw childhood development issues had water containing above 6mg/L and one area had a range from 118mg/kg to 1,361mg/kg (thank you coal mining). Another confounding factor is that many of the areas with high fluoride levels also had high aluminum, mercury, and arsenic levels as well. I'd like to see a study comparing IQs or development with actual usage levels and without the heavy metal pollutants from industry. Full HSPH study: http://ehp.niehs.nih.gov/wp-content/uploads/2012/09/ehp.1104912.pdf http://ehp.niehs.nih.gov/wp-content/uploads/2012/09/ehp.1104...
- 11y ago

NoMoreNicksLeft 11y ago

Did anyone expect it to do so? Fluorine production was a proxy for uranium production if the only use for fluorine was for uranium production. Couldn't have the Soviets knowing how many atom bombs we were building, so we needed to use it for something else too. Something so massive that it would make it impossible to calculate how much was used for nukes. And so we put it in the water supply as an additive.

ColinDabritz 11y ago
Interesting, do you have a citation for this one? It reminds me of the "carrots help you see better" myth that began as WWII propaganda [1] as a cover for radar and has been very persistent since. [1] http://www.washingtonpost.com/news/speaking-of-science/wp/2014/12/15/no-carrots-dont-make-your-eyesight-better/ http://www.washingtonpost.com/news/speaking-of-science/wp/20...
happyscrappy 11y ago
Mandrake, have you ever seen a commie drink a glass of water?
- stcredzero 11y ago
  "Purity of Essence"
vonmoltke 11y ago
Huh? Fluorine's oldest and most common industrial use is in steelmaking. It is also used heavily in refrigerants.
x5n1 11y ago
According to the Fluorine Deception, they needed a way to get rid of the effluent so they made it a health product rather than toxic waste. That book however has been dismissed by most supporters of fluoridation as written by a nutbar. http://www.amazon.com/The-Fluoride-Deception-Christopher-Bryson/dp/1583227008 http://www.amazon.com/The-Fluoride-Deception-Christopher-Bry... "Concerns over fluoridated drinking water have long been derided as the obsession of McCarthyite cranks. But this muckraking j’accuse asserts that fluoride is indeed a dire threat to public health, one foisted upon the nation by a vast conspiracy—not of Communist agents, but of our very own military-industrial complex. Investigative reporter Bryson revisits the decades-long controversy, drawing on mountains of scientific studies, some unearthed from secret archives of government and corporate laboratories, to question the effects of fluoride and the motives of its leading advocates. The efficacy of fluoridated drinking water in preventing tooth decay, he contends, is dubious. Fluoride in its many forms may be one of the most toxic of industrial pollutants, and Bryson cites scientific analyses linking fluoridated drinking water to bone deformities, hyperactivity and a host of other complaints. The post-war campaign to fluoridate drinking water, he claims, was less a public health innovation than a public relations ploy sponsored by industrial users of fluoride—including the government’s nuclear weapons program. Legendary spin doctors like Edward Bernays exploited the tenuous link between dental hygiene and fluoridation to create markets to stimulate fluoride production and to prove the innocuousness of fluoride compounds, thereby heading off lawsuits by factory workers and others poisoned by industrial fluoride pollution. Bryson marshals an impressive amount of research to demonstrate fluoride’s harmfulness, the ties between leading fluoride researchers and the corporations who funded and benefited from their research, and what he says is the duplicity with which fluoridation was sold to the people. The result is a compelling challenge to the reigning dental orthodoxy, which should provoke renewed scientific scrutiny and public debate."

jessriedel 11y ago

Just so everyone is clear: this review found that there is little evidence that water fluoridation has any benefits. It does not dispute that fluoride in toothpaste reduces tooth decay. > Studies that attest to the effectiveness of fluoridation were generally done before the widespread usage of fluoride-containing dental products like rinses and toothpastes in the 1970s and later, according to the recent Cochrane study. So while it may have once made sense to add fluoride to water, it no longer appears to be necessary or useful, Thiessen says. > It has also become clear in the last 15 years that fluoride primarily acts topically, according to the CDC. It reacts with the surface of the tooth enamel, making it more resistant to acids excreted by bacteria. Thus, there's no good reason to swallow fluoride and subject every tissue of your body to it, Thiessen says. > Another 2009 review by the Cochrane group clearly shows that fluoride toothpaste prevents cavities.

mikeyouse 11y ago
The theory I've encountered is that fluoridation previously had an impact on cavity-prevention before people were actually brushing their teeth with fluoridated toothpaste. Now that toothbrushing is much more common, the impact has waned. Late edit; Here's a look at toothbrushing frequency in Europe by country from 1994 - 2010: http://i.imgur.com/VVBldAy.jpg http://i.imgur.com/VVBldAy.jpg Just imagine how much improvement you'd see from if the chart started in the 1940's and 1950's when many cities began fluoridating their water supplies. Not to mention that many early toothpastes were often ineffective at preventing cavities by primarily relying on baking soda and peroxide. (Full brushing frequency study: http://eurpub.oxfordjournals.org/content/25/suppl_2/20 http://eurpub.oxfordjournals.org/content/25/suppl_2/20 )
- gcb0 11y ago
  remember that non controlled measurements are worthless. same time they started water fluoridation the population also started to pay attention to brushing their teeth. or do you think the govt took the initiative at any point in history?
scott_s 11y ago
Unfortunately, it's not accurate to say there is no evidence. There is evidence, it's just old evidence. For some reason, Newsweek decided to focus on the fact that there is no evidence that fluoridation is helpful for adults, and that the evidence for children is almost all from before 1975. That is important since behaviors may have changed post-1975. The "Plain language summary" from the authors - their words, so this is the authors of the study synthesizing their conclusions for a lay audience - is clear: Data suggest that the introduction of water fluoridation resulted in a 35% reduction in decayed, missing or filled baby teeth and a 26% reduction in decayed, missing or filled permanent teeth. It also increased the percentage of children with no decay by 15%. Although these results indicate that water fluoridation is effective at reducing levels of tooth decay in children's baby and permanent teeth, the applicability of the results to current lifestyles is unclear because the majority of the studies were conducted before fluoride toothpastes and the other preventative meaures were widely used in many communities around the world. There was insufficient information available to find out whether the introduction of a water fluoridation programme changed existing differences in tooth decay across socioeconomic groups. There was insufficient information available to understand the effect of stopping water fluoridation programmes on tooth decay. No studies met the review’s inclusion criteria that investigated the effectiveness of water fluoridation for preventing tooth decay in adults, rather than children. This is from http://onlinelibrary.wiley.com/doi/10.1002/14651858.CD010856.pub2/abstract http://onlinelibrary.wiley.com/doi/10.1002/14651858.CD010856.... Thanks to HN user giarc (https://news.ycombinator.com/item?id=9807427 https://news.ycombinator.com/item?id=9807427) for pointing it out.

godgod 11y ago

And yet municipalities put it in our water. I feel poisoned drinking tap water.

fapjacks 11y ago

Oh, so then that means that fluoride is actually for mind control. Gotcha.

fapjacks 11y ago
I see the sarcasm was completely lost on at least four geniuses.
- biot 11y ago
  Fortunately for the quality of this site, there were only a few people who lacked the self-restraint needed to avoid pointing out such a painfully obvious, reddit-esque joke.
  - fapjacks 11y ago
    >quality I take it you're new here. HN has been "tech reddit" for at least a couple of years now. (This will probably whoosh miles overhead, too).

ChaoticGood 11y ago

It is a great idea to revisit public policies that were put into place at the same time Doctors were advertising Cigarettes as healthy. Water is a precious resource and should be protected as such. "Generally, in Germany fluoridation of drinking water is forbidden. The relevant German law allows exceptions to the fluoridation ban on application. The argumentation of the Federal Ministry of Health against a general permission of fluoridation of drinking water is the problematic nature of compuls[ory] medication." (Gerda Hankel-Khan, Embassy of Federal Republic of Germany, September 16, 1999).[0] Germany halted its water fluoridation in the 1970s and France never started.[1] [0] http://www.slweb.org/50reasons.html http://www.slweb.org/50reasons.html [1] http://www.theguardian.com/world/2013/sep/17/water-fluoridation http://www.theguardian.com/world/2013/sep/17/water-fluoridat...

dd9990 11y ago
Fluoridation has been mandatory in Ireland since the 50s. Considering how radically Irish lifestyles have changed in the last few decades (less poverty, better access to dental products, inexpensive/free dental care etc) I think it's crazy we're still forcefully mass medicating the majority of the population without their consent. Although mostly harmless, excessive fluoridation was recently linked to hypothyroidism in a UK study. I think it's time to seriously reconsider the decision instead of the occasional self-assurance everything is fine as is.
_delirium 11y ago
Generally Europe doesn't fluoridate its water, true, but the practical effect is a bit more nuanced. For example, Germany has mostly moved its fluoridation program from water to salt: http://www.ncbi.nlm.nih.gov/pubmed/16156167 http://www.ncbi.nlm.nih.gov/pubmed/16156167 In Denmark the water isn't fluoridated, but its natural levels of fluoride are only slightly lower than the levels that U.S. cities add (for example in the Copenhagen water supply, fluoride is around 0.6 mg/L). So it's a bit pedantic to claim that it isn't fluoridated. It's true that the utility company is not adding more fluoride to the water, but the end result is still that the pipes are delivering tap water with fluoride in it.

nsxwolf 11y ago

Here comes all the kids with rotten teeth and measles.

evunveot 11y ago

From what I've read, we've already identified the specific bacteria responsible for tooth decay [1], but there seems to have no interest in developing treatments based on that insight. Instead we're supposed to essentially sterilize our mouths and remineralize our teeth (which is something saliva does naturally) with topical fluoride twice a day. My cat has never brushed her teeth, and they're fine, presumably because the microbiome in her mouth is in a state where bacteria that secrete lactic acid are crowded out by benign species. Granted, she doesn't eat many simple sugars, but I have had a vet recommend brushing her teeth twice a day as a preventative measure, which blew my mind. I hope I live to see the day when the extent of oral hygiene maintenance and bad breath prevention is a toothpick and an occasional probiotic mouthwash or something. [1] https://en.wikipedia.org/wiki/Dental_caries#Bacteria https://en.wikipedia.org/wiki/Dental_caries#Bacteria

giarc 11y ago
This made the news awhile ago, it's called STAMP (specifically targeted antimicrobial peptides). Here's a 2011 article that seems to show some progress. http://www.ncbi.nlm.nih.gov/pubmed/21860239 http://www.ncbi.nlm.nih.gov/pubmed/21860239
- mrfusion 11y ago
  Wow, sounds promising. Is that something you can buy?
- knodi123 11y ago
  Evora will be glad to sell you probiotic lozenges containing benign mouth bacteria that can outcompete the harmful ones. Personally, I used them for two months as directed, and saw no real difference. Can't wait for a real product, I just hope it doesn't start off costing $200/month like some probiotics I've seen.
  - jws 11y ago
    Curious: How would you observe a difference in two months? (HN being what it is, I'm half expecting you to tell me you were assaying your mouth bacteria with an electron microscope you made and some OpenCV hacked together on…)

giarc 11y ago

Can we change the link to the actual Cochrane review which does provide a plain language interpretation of the results? http://onlinelibrary.wiley.com/doi/10.1002/14651858.CD010856.pub2/abstract http://onlinelibrary.wiley.com/doi/10.1002/14651858.CD010856...

jmckib 11y ago
Here's an anchor link directly to the plan language summary. http://onlinelibrary.wiley.com/doi/10.1002/14651858.CD010856.pub2/abstract#shortAbstract http://onlinelibrary.wiley.com/doi/10.1002/14651858.CD010856...
dang 11y ago
The Newsweek article contains considerable additional reporting, and does not appear (at first glance) to distort what the Cochrane review says. Unless that's wrong, I don't think we need to swap the URL.

cvwright 11y ago

They don't fluoridate the water here in Portland, OR. Compared to other parts of the country where I've lived, the difference in people's teeth is pretty shocking. I haven't heard any alternative hypothesis that would explain this difference better than the lack of fluoridation here. As I understand the article, they're saying that they couldn't find rigorous studies demonstrating the beneficial effects of fluoride. They don't claim there's any evidence against fluoride having beneficial effects, just that the studies haven't been done.

stephengillie 11y ago
There's too much inertia in favor of fluoride being beneficial for any serious researcher to risk their credibility. Everyone "knows" fluoride makes teeth stronger, like lettuce being healthy to eat, or global warming is human-caused. In fact, even discussing the possibility is too much for most people to entertain. They think you're wasting their time with fantasy and falsehood, like conspiracy theorists always do. Fluoride being bad for teeth is as believable as airliners dropping chemtrails everywhere, or jet fuel not "spheroiding" steel after hours of heating.
- stephengillie 11y ago
  See? Even posting about the idea of researching it merits a downvote. The idea that fluoride has no benefits is as popular as Apple and Microsoft merging.
pavedwalden 11y ago
With over half of people currently in the Portland metro area having been born elsewhere, it would be hard to sort out whether cavities were the result of fluoride deficiency or some sort of selection bias in who chooses to live there. I never noticed a lot of fillings when I lived in Portland, but then I wasn't looking inside people's mouths.
fnordfnordfnord 11y ago
How many dentists per capita are there in Portland compared to similar cities. Edit, I checked. It seems that it might be higher than average.

cromulent 11y ago

Correlation. Everyone should get the right amount of fluoride. This is actually quite difficult to measure and achieve. WHO seem to have a good viewpoint: "The effects of fluoride are best predicted by the dose (i.e. mg fluoride per kg of body weight per day), the duration of exposure and other factors such as age (e.g. dental fluorosis). However, most epidemiological studies concerning the effects of fluoride on teeth and bone have correlated the effects with the concentration of fluoride in the drinking-water (mg l–1 fluoride) consumed rather than total fluoride exposure. ... Perhaps the best general advice that can be given in relation to local conditions is that, at a minimum, the fluoride level in local water supplies should be monitored and the population examined for signs of excessive fluoride exposure (e.g. moderate and/or severe dental fluorosis and crippling skeletal fluorosis). Where treatment to remove fluoride is practised, chemicals used should be of a grade suitable for use in drinking-water supply as outlined in the WHO Guidelines for Drinking-water Quality." http://www.who.int/water_sanitation_health/publications/fluoride_drinking_water_full.pdf?ua=1 http://www.who.int/water_sanitation_health/publications/fluo...

jug5 11y ago

Keep drinking that fluoride folks. Enjoy the flavor.

jrcii 11y ago

I can no longer sit back and allow Communist infiltration, Communist indoctrination, Communist subversion and the international Communist conspiracy to sap and impurify all of our precious bodily fluids.

jjulius 11y ago
Mandrake, have you ever seen a Commie drink a glass of water?
- vbnmvbnmvbnm 11y ago
  Ice cream, Mandrake? Children's ice cream?

JeremyNT 11y ago

This article has such a bad headline. The important thing to note here is that this review is looking for the impacts of fluoridation since the 1970s. The evidence remains clear that fluoridation is better than nothing at preventing cavities! The question at hand is whether it's still important now that we have widespread adoption of fluoride toothpaste. This Cochrane study concludes, as many Cochrane reviews do, that there's not yet enough high quality evidence to answer this question. The takeaway here shouldn't be the absurd headline that "fluoridation may not prevent cavities," it should be "we should study how effective fluoridation is now that we have added other successful interventions."

SuddsMcDuff 11y ago
The headline introduces an element of doubt in something that was previously reckoned to be conclusive. I'd say it's pretty effective.

lutorm 11y ago

Having grown up in Sweden, being told that fluoride applied topically was functional at reducing caries but that eating toothpaste or swallowing the fluoride rinse that we got in elementary school was bad for you, I was astonished to learn that some countries put it in their water. Even in the U.S., toothpaste containers warn you not to swallow it and contact a Poison Control Center if you accidentally do. And then they put it in tap water? It just seems really inconsistent.

aggie 11y ago
Just a guess but those cases are probably due to the fluoride concentration of the rinse and toothpaste. Things that can be beneficial at small doses can be harmful in larger doses.
sliverstorm 11y ago
I suspect that the "don't eat toothpaste" stuff is mostly overblown and primarily just to ensure kids don't eat toothpaste like candy (which kids will do). In large quantities (say, a whole tube) it will make you throw up, and maybe you could accumulate too much flouride. Is a pea-sized drop on your toothbrush going to hurt you if you swallow it, no, but there's no reason to swallow toothpaste and a number of mild reasons why you probably shouldn't.
snowwrestler 11y ago
The actual warning is: > Keep out of reach of children under 6 years of age. If more than used for brushing is accidentally swallowed, get medical help or contact a Poison Control Center right away. Note: more than used for brushing So, it's fine to swallow your toothpaste if you want. But if your 4 year swallows a whole tube of it, they are probably going to get sick to their stomach.
DanBC 11y ago
Toothpaste has lots of fluoride in, because it's a topical treatment. Eating the toothpaste risks "fluorosis" - discoloured teeth. https://en.wikipedia.org/wiki/Dental_fluorosis https://en.wikipedia.org/wiki/Dental_fluorosis
11y ago

marze 11y ago

My policy: if someone wants me to eat poison, even if in small doses, there better be some really bulletproof evidence of benefit.

ownedthx 11y ago

Since there are US cities like Texarkana, AR that have not have fluoride in the water ever, it seems they would be a decent way to harvest some data quickly and get to the bottom of this. Anecdotally, I know a dentist that would work 2 days a week there as a sort of 'import-a-dentist' program, and she thought teeth were, in general, in much worse shape there than Little Rock, AR (3 hours away). Not enough to go on obviously.

facetube 11y ago
Portland, Oregon doesn't have any fluoride in its water supply either, for what it's worth.
- ownedthx 11y ago
  Seemingly a good list; http://fluoridealert.org/content/communities/ http://fluoridealert.org/content/communities/
stephengillie 11y ago
While there's lots of anecdotal evidence trying to correlate these ideas, supposedly the statistical correlation isn't there.

SQL2219 11y ago

yea well, it reduces IQ, so we're keeping it. http://www.hsph.harvard.edu/news/features/fluoride-childrens-health-grandjean-choi/ http://www.hsph.harvard.edu/news/features/fluoride-childrens...

jane_is_here 11y ago

Yet another excellent reason to not get your scientific information from the popular media.

BuckRogers 11y ago

Wasn't this obvious the whole time? You don't need a study to show that drinking fluoridated water doesn't help your teeth. Fluoride is applied topically.

gtrubetskoy 11y ago

An educational video from Univ. of Nottingham, if you don't know how nasty (and fun) Fluorine is: https://www.youtube.com/watch?v=vtWp45Eewtw https://www.youtube.com/watch?v=vtWp45Eewtw (and they explain the tooth enamel theory towards the end as well).

nixy 11y ago

Methods to prevent tooth decay were investigated and documented in Sweden back in the 30's and 40's. Studies were carried out at a mental hospital where patients were force fed sugary sweets to provoke caries. I believe fluoridation was one of the things found to help prevent caries. https://en.wikipedia.org/wiki/Vipeholm_experiments https://en.wikipedia.org/wiki/Vipeholm_experiments