# Medical benefits of dental floss unproven - what about Fluoride ? **URL:** \ **Category:** Factual Questions\ **Created:** [August 9, 2019, 5:35pm UTC](https://boards.straightdope.com/t/medical-benefits-of-dental-floss-unproven-what-about-fluoride/838416 "2019-08-09T17:35:21Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![am77494](https://avatars.discourse-cdn.com/v4/letter/a/d2c977/32.png) [@am77494](https://boards.straightdope.com/u/am77494)\ **Post date:** [August 9, 2019, 5:35pm UTC](https://boards.straightdope.com/t/medical-benefits-of-dental-floss-unproven-what-about-fluoride/838416/1 "2019-08-09T17:35:21Z")
A few years back, it was as published that the data showed that flossing had no medical benefits. [null | AP News](https://apnews.com/f7e66079d9ba4b4985d7af350619a9e3) Are there similar studies on fluoride treatments ? ---
**Author:** ![AlsoNamedBort](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/alsonamedbort/32/3213_2.png) [@AlsoNamedBort](https://boards.straightdope.com/u/AlsoNamedBort)\ **Post date:** [August 9, 2019, 5:49pm UTC](https://boards.straightdope.com/t/medical-benefits-of-dental-floss-unproven-what-about-fluoride/838416/2 "2019-08-09T17:49:42Z")
> [@am77494](#): > > A few years back, it was as published that the data showed that flossing had no medical benefits. That’s not what it says. It says that there isn’t adequate research showing flossing makes a difference. ---
**Author:** ![Bear\_Nenno](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bear_nenno/32/3358_2.png) [@Bear\_Nenno](https://boards.straightdope.com/u/Bear_Nenno)\ **Post date:** [August 9, 2019, 5:52pm UTC](https://boards.straightdope.com/t/medical-benefits-of-dental-floss-unproven-what-about-fluoride/838416/3 "2019-08-09T17:52:06Z")
That’s not what the studies said. There is a difference between a “lack of scientific evidence proving that flossing has a medical benefit” and “evidence that flossing has no medical benefit”. The studies only purport to show the former, not that latter. The issue, as your own cite shows, is that legitimate scientific studies are expensive and problematic. There has been no study showing that flossing has no medical benefit. There hasn’t been a good study showing it does, either. As for fluoride, there have been plenty of studies showing that increased sources of fluoride over the past decades have elevated our exposure to potentially harmful levels. There is a listing of many such studies on the IOAMT Fact Sheet, here: [https://files.iaomt.org/wp-content/uploads/IAOMT-Fact-Sheet-on-Fluoride-and-Human-Health.pdf](https://files.iaomt.org/wp-content/uploads/IAOMT-Fact-Sheet-on-Fluoride-and-Human-Health.pdf) ---
**Author:** ![pohjonen](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/pohjonen/32/423_2.png) [@pohjonen](https://boards.straightdope.com/u/pohjonen)\ **Post date:** [August 9, 2019, 6:14pm UTC](https://boards.straightdope.com/t/medical-benefits-of-dental-floss-unproven-what-about-fluoride/838416/4 "2019-08-09T18:14:01Z")
I think periodontal disease springs from [autoimmune issues](https://www.ncbi.nlm.nih.gov/pubmed/27664383). Regular cleanings and flossing are like frequent bathing to treat your lupus. Nothing elicits lots of silent blinking from my doctor like complaining about my autoimmune symptoms. ETA: I didn’t notice this thread was in GQ. I withdraw my snarky response. ---
**Author:** ![RitterSport](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/rittersport/32/6326_2.png) [@RitterSport](https://boards.straightdope.com/u/RitterSport)\ **Post date:** [August 9, 2019, 6:30pm UTC](https://boards.straightdope.com/t/medical-benefits-of-dental-floss-unproven-what-about-fluoride/838416/5 "2019-08-09T18:30:48Z")
> [@Bear\_Nenno](#): > > That’s not what the studies said. There is a difference between a “lack of scientific evidence proving that flossing has a medical benefit” and “evidence that flossing has no medical benefit”. The studies only purport to show the former, not that latter. The issue, as your own cite shows, is that legitimate scientific studies are expensive and problematic. There has been no study showing that flossing has no medical benefit. There hasn’t been a good study showing it does, either. > As for fluoride, there have been plenty of studies showing that increased sources of fluoride over the past decades have elevated our exposure to potentially harmful levels. There is a listing of many such studies on the IOAMT Fact Sheet, here: [https://files.iaomt.org/wp-content/uploads/IAOMT-Fact-Sheet-on-Fluoride-and-Human-Health.pdf](https://files.iaomt.org/wp-content/uploads/IAOMT-Fact-Sheet-on-Fluoride-and-Human-Health.pdf) That’s a terrible cite: [International Academy of Oral Medicine and Toxicology - RationalWiki](https://rationalwiki.org/wiki/International_Academy_of_Oral_Medicine_and_Toxicology) [https://www.quackwatch.org/04ConsumerEducation/Nonrecorg/iaomt.html](https://www.quackwatch.org/04ConsumerEducation/Nonrecorg/iaomt.html) Fluoride has definitely led to a reduction in cavities and tooth decay: > **[Fluoridation in Water](https://www.ada.org/resources/community-initiatives/fluoride-in-water)** > > Browse facts, clinical guidelines and FAQ's regarding fluoride in water and read about the ADA's advocacy for the fluoridation of water in public water supplies. Here’s one from the National Institutes of Health: > **[The Fluoride Debate: The Pros and Cons of Fluoridation](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6195894/)** > > Fluoride is one of the most abundant elements found in nature. Water is the major dietary source of fluoride. The only known association with low fluoride intake is the risk of dental caries. Initially, fluoride was considered beneficial when given... Here’s the conclusion: > [@](#): > > Dental treatments are expensive throughout the world. The cost of dentistry has hardly been reduced, even in countries where the decline in caries began 30 years ago. Thus, extension of preventive dentistry is still indispensable for improving oral health (12). The absence of dental care and poor hygiene are still considered the main causes of dental decay (34). Although multifactorial in origin, caries is a preventable disease, with fluoride as a preventive agent used worldwide. Several modes of fluoride use have evolved, each with its own recommended concentration, frequency of use, and dosage schedule. Concurrently, recent opposition has been growing worldwide against fluoridation, emphasizing the potential and serious risk of toxicity. Since the fluoride benefit is mainly topical, perhaps it is better to deliver fluoride directly to the tooth instead of ingesting it (34). Fluoride toothpaste, rinses and varnish applications have proven their effectiveness in some countries, but they are still not universally affordable. Since the OP is just asking about fluoride, not the method of delivery, there is little doubt that topical fluoride (in toothpaste, for example) is effective in preventing tooth decay. ---
**Author:** ![EdelweissPirate](https://avatars.discourse-cdn.com/v4/letter/e/8491ac/32.png) [@EdelweissPirate](https://boards.straightdope.com/u/EdelweissPirate)\ **Post date:** [August 9, 2019, 7:00pm UTC](https://boards.straightdope.com/t/medical-benefits-of-dental-floss-unproven-what-about-fluoride/838416/6 "2019-08-09T19:00:13Z")
> [@AlsoNamedBort](#): > > That’s not what it says. It says that there isn’t adequate research showing flossing makes a difference. Or, put another way: “The few investigations into the subject have major design flaws. Inadequate though these were, none of them found that flossing is ineffective or harmful. Flossing probably doesn’t hurt, but we can’t really say how much it helps or even if it helps.” I wrote that out of frustration with the standard medical expression: “There is no evidence to show that X is effective in preventing Y.” While that’s often literally true, it’s too often read by laypeople (and a surprising number of physicians) as “X is probably ineffective at preventing Y.” My complaint is that “there is no evidence” doesn’t distinguish between - “no one has studied that yet,” - “some studies exist, but I think they’re horseshit,” - “some studies exist, but there’s broad consensus that they’re horseshit,” and - “there is definitive proof that X does not prevent Y.” It would be irresponsible and grossly misleading to say “there is no evidence to show that X prevents Y” when there’s definitive proof that it doesn’t, but it’s still a true statement. Saying that “there is no evidence” can be appropriate and useful in certain contexts, but it’s often a terrible way to communicate the state of our current understanding to the general public. It’s commonly observed that the absence of evidence is not evidence of absence. It’s common partly because (IMHO) it’s an important corollary to “no evidence.” I’d speculate that the noncommittal vagueness in “there is no evidence to show…” stems from an overzealous application of the precautionary principle. But this is GQ, so I’ll refrain from making that observation. 😉 ---
**Author:** ![EdelweissPirate](https://avatars.discourse-cdn.com/v4/letter/e/8491ac/32.png) [@EdelweissPirate](https://boards.straightdope.com/u/EdelweissPirate)\ **Post date:** [August 9, 2019, 7:25pm UTC](https://boards.straightdope.com/t/medical-benefits-of-dental-floss-unproven-what-about-fluoride/838416/7 "2019-08-09T19:25:41Z")
> [@RitterSport](#): > > […] > Since the OP is just asking about fluoride, not the method of delivery, there is little doubt that topical fluoride (in toothpaste, for example) is effective in preventing tooth decay. I’m no chemist, but the mechanism for this seems to be well understood—apparently, the fluoride enables the remineralization of teeth by substituting fluorapatite for the “native” hydroxyapatite. I believe the OP is a chemical engineer (and said so in another thread), so this question surprises me a bit. OP, do you believe the the mechanism of action is misunderstood? Do you have some other reason to think that fluoride is ineffective? Unlike myself, you have considerable expertise in chemistry, so I’m curious about what’s prompting you to ask. ---
**Author:** ![Dereknocue67](https://avatars.discourse-cdn.com/v4/letter/d/6de8d8/32.png) [@Dereknocue67](https://boards.straightdope.com/u/Dereknocue67)\ **Post date:** [August 10, 2019, 7:05am UTC](https://boards.straightdope.com/t/medical-benefits-of-dental-floss-unproven-what-about-fluoride/838416/8 "2019-08-10T07:05:38Z")
Flossing all of your teeth is totally unnecessary. This is a proven fact. Dentists will tell you it’s only necessary to floss the teeth you want to keep. ---
**Author:** ![pool](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/pool/32/4152_2.png) [@pool](https://boards.straightdope.com/u/pool)\ **Post date:** [August 10, 2019, 7:15am UTC](https://boards.straightdope.com/t/medical-benefits-of-dental-floss-unproven-what-about-fluoride/838416/9 "2019-08-10T07:15:07Z")
Does the OP need a study that the spinach you had for lunch last Wednesday and got lodged in your teeth might start to smell if you don’t floss from time to time? ---
**Author:** ![Crafter\_Man](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/crafter_man/32/458_2.png) [@Crafter\_Man](https://boards.straightdope.com/u/Crafter_Man)\ **Post date:** [August 10, 2019, 11:38am UTC](https://boards.straightdope.com/t/medical-benefits-of-dental-floss-unproven-what-about-fluoride/838416/10 "2019-08-10T11:38:32Z")
> [@pool](#): > > Does the OP need a study that the spinach you had for lunch last Wednesday and got lodged in your teeth might start to smell if you don’t floss from time to time? This. A rigorous study is not necessary because we already know the answer: cleaning your teeth & gums a couple times a day is important for good oral health. This includes _ **all** _ of the surface area. In addition to cleaning the areas on the tooth surfaces between the teeth, flossing breaks up the bacteria that is growing on the gums between the teeth. There’s no reason to spend millions of dollars on a study when the question can be answered using common sense. ---
**Author:** ![Bear\_Nenno](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bear_nenno/32/3358_2.png) [@Bear\_Nenno](https://boards.straightdope.com/u/Bear_Nenno)\ **Post date:** [August 10, 2019, 2:38pm UTC](https://boards.straightdope.com/t/medical-benefits-of-dental-floss-unproven-what-about-fluoride/838416/11 "2019-08-10T14:38:56Z")
> [@RitterSport](#): > > That’s a terrible cite: [International Academy of Oral Medicine and Toxicology - RationalWiki](https://rationalwiki.org/wiki/International_Academy_of_Oral_Medicine_and_Toxicology) > [https://www.quackwatch.org/04ConsumerEducation/Nonrecorg/iaomt.html](https://www.quackwatch.org/04ConsumerEducation/Nonrecorg/iaomt.html) > > Fluoride has definitely led to a reduction in cavities and tooth decay: > [Fluoridation in Water | American Dental Association](https://www.ada.org/en/public-programs/advocating-for-the-public/fluoride-and-fluoridation/5-reasons-why-fluoride-in-water-is-good-for-communities) > > Here’s one from the National Institutes of Health: > > [The Fluoride Debate: The Pros and Cons of Fluoridation - PMC](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6195894/) > > Here’s the conclusion: > > Since the OP is just asking about fluoride, not the method of delivery, there is little doubt that topical fluoride (in toothpaste, for example) is effective in preventing tooth decay. I was citing the studies compiled in the bibliography of that fact sheet. Attacking the agency responsible for compiling the studies is an ad hominem. Further, I never claimed that Flouride does not prevent cavities or tooth decay. Nor did I imply that any of those studies did so. I merely informed the OP that there are plenty of studies conducted on the use of Flouride which warn of its overuse. Citing a study that shows Fluoride prevents cavities does not counter the claim that too much Fluoride can be dangerous. ---
**Author:** ![Jackmannii](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/jackmannii/32/311_2.png) [@Jackmannii](https://boards.straightdope.com/u/Jackmannii)\ **Post date:** [August 10, 2019, 10:42pm UTC](https://boards.straightdope.com/t/medical-benefits-of-dental-floss-unproven-what-about-fluoride/838416/12 "2019-08-10T22:42:55Z")
> [@Bear\_Nenno](#): > > I merely informed the OP that there are plenty of studies conducted on the use of Flouride which warn of its overuse. There aren’t “plenty” of water fluoridation studies showing significant health effects; there’s some evidence that dental fluorosis (staining of teeth, often difficult to detect) can occur if fluoride levels are too high, something known from situations in which fluoride is naturally elevated in drinking water. For this reason, the U.S. government a few years ago recommended a lower level of municipal water fluoridation, as people have been gettting fluoride from other sources including but not limited to toothpaste. There are of course “plenty” of alt health and conspiracy-minded websites warning of all sorts of dire chronic ailments from drinking fluoridated water. For the evidence-based crowd (which I hope includes Dopers), there’s [abundant](https://www.ada.org/en/publications/ada-news/2018-archive/may/studies-reaffirm-safety-of-fluoridation) [reassuring data](https://www.cdc.gov/fluoridation/guidelines/cdc-statement-on-community-water-fluoridation.html). ---
**Author:** ![friedo](https://avatars.discourse-cdn.com/v4/letter/f/8edcca/32.png) [@friedo](https://boards.straightdope.com/u/friedo)\ **Post date:** [August 11, 2019, 5:18am UTC](https://boards.straightdope.com/t/medical-benefits-of-dental-floss-unproven-what-about-fluoride/838416/13 "2019-08-11T05:18:39Z")
> [@Dereknocue67](#): > > Flossing all of your teeth is totally unnecessary. This is a proven fact. Dentists will tell you it’s only necessary to floss the teeth you want to keep. Dentists say a lot of things. There’s a lot about the practice of dentistry that’s based on somewhat inadequate, if any, scientific consensus. Flossing certainly doesn’t hurt, but its _proven_ benefits are quite nebulous. ---
**Author:** ![RitterSport](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/rittersport/32/6326_2.png) [@RitterSport](https://boards.straightdope.com/u/RitterSport)\ **Post date:** [August 11, 2019, 10:56am UTC](https://boards.straightdope.com/t/medical-benefits-of-dental-floss-unproven-what-about-fluoride/838416/14 "2019-08-11T10:56:38Z")
> [@Bear\_Nenno](#): > > I was citing the studies compiled in the bibliography of that fact sheet. Attacking the agency responsible for compiling the studies is an ad hominem. Further, I never claimed that Flouride does not prevent cavities or tooth decay. Nor did I imply that any of those studies did so. I merely informed the OP that there are plenty of studies conducted on the use of Flouride which warn of its overuse. Citing a study that shows Fluoride prevents cavities does not counter the claim that too much Fluoride can be dangerous. First of all, the OP didn’t ask about the risk of over-fluoridation, but whether there’s evidence that fluoride has medical benefits. Do you agree that the answer to that is yes? Your answer was basically off-topic, since everything that has medical or health benefits will be dangerous if levels get too high. Second, I looked at the cites and the first was a cite to a paper published by themselves and the second was to a veterinary paper. I didn’t bother looking any further. ---
**Author:** ![Dereknocue67](https://avatars.discourse-cdn.com/v4/letter/d/6de8d8/32.png) [@Dereknocue67](https://boards.straightdope.com/u/Dereknocue67)\ **Post date:** [August 11, 2019, 11:29am UTC](https://boards.straightdope.com/t/medical-benefits-of-dental-floss-unproven-what-about-fluoride/838416/15 "2019-08-11T11:29:54Z")
> [@friedo](#): > > Dentists say a lot of things. There’s a lot about the practice of dentistry that’s based on somewhat inadequate, if any, scientific consensus. Flossing certainly doesn’t hurt, but its _proven_ benefits are quite nebulous. Sounds like the philosophy of a toothless individual. ---
**Author:** ![Ulfreida](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ulfreida/32/8014_2.png) [@Ulfreida](https://boards.straightdope.com/u/Ulfreida)\ **Post date:** [August 11, 2019, 11:55am UTC](https://boards.straightdope.com/t/medical-benefits-of-dental-floss-unproven-what-about-fluoride/838416/16 "2019-08-11T11:55:47Z")
I read a discussion of the news report when it was published. One point I remember was that one reason few good studies about dentistry practices have been done is that tooth damage is not reversible; teeth – and gums also to a different extent – are not self-healing. You are not going to find a lot of ethically-designed studies which will end in the control group living with damaged teeth for the rest of their lives. ---
**Author:** ![DSeid](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dseid/32/20194_2.png) [@DSeid](https://boards.straightdope.com/u/DSeid)\ **Post date:** [August 11, 2019, 1:17pm UTC](https://boards.straightdope.com/t/medical-benefits-of-dental-floss-unproven-what-about-fluoride/838416/17 "2019-08-11T13:17:56Z")
> [@Crafter\_Man](#): > > … A rigorous study is not necessary because we already know the answer … \ … > There’s no reason to spend millions of dollars on a study when the question can be answered using common sense. “Common sense”, or at least what people _thought_ was common sense, has very often been wrong. especially in matters of healthcare. Things people think they “already know” are very commonly myths. Or religious belief systems. [Reality is](https://www.usnews.com/news/articles/2016-05-02/how-many-americans-floss-their-teeth) that only 30% of Americans floss daily and 32% _never_ floss, or at least admit such when polled. (Generally infrequent and never flossers lie to their dentists.) Apparently some who do floss daily don’t “do it incorrectly.” Right now there is not evidence that the never and infrequent flossers are on the basis of not flossing at any increase dental, gum, or other general health increased risks. There is no evidence that it causes harm either and evidence that is convincing that it does not decrease … or increase … any of those risks is also lacking. Certainly if there was a clinically significant difference it would be not hard to find, at least as suggestive data using cohort studies and matching for known confounders like SES, dietary habits, and smoking status. Basically there should be a clear epidemic of gingivitis among the nevers and very little in the daily flossers. The lack of such studies is pretty damning. Either the question is too trivial to ask, or the studies have been done and aren’t published as negative findings are sometimes not. Flossing is indeed a low cost and most likely low risk behavior. It may make your breath smell better. But no, we do not “already know the answer” and there is no evidence whatsoever that the minority who floss daily (or more) are, from a health perspective, any better off from their daily time and hassle investments than _the majority who don’t._ ---
**Author:** ![friedo](https://avatars.discourse-cdn.com/v4/letter/f/8edcca/32.png) [@friedo](https://boards.straightdope.com/u/friedo)\ **Post date:** [August 11, 2019, 2:46pm UTC](https://boards.straightdope.com/t/medical-benefits-of-dental-floss-unproven-what-about-fluoride/838416/18 "2019-08-11T14:46:23Z")
> [@Dereknocue67](#): > > Sounds like the philosophy of a toothless individual. No. Do you actually have anything relevant to contribute? ---
**Author:** ![SlackerInc](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/slackerinc/32/275_2.png) [@SlackerInc](https://boards.straightdope.com/u/SlackerInc)\ **Post date:** [August 11, 2019, 5:46pm UTC](https://boards.straightdope.com/t/medical-benefits-of-dental-floss-unproven-what-about-fluoride/838416/19 "2019-08-11T17:46:34Z")
> [@pool](#): > > Does the OP need a study that the spinach you had for lunch last Wednesday and got lodged in your teeth might start to smell if you don’t floss from time to time? When I feel something wedged between my teeth, I floss in that spot. Otherwise, I just brush my teeth regularly and thoroughly (with no toothpaste, just a lot of rinsing with water), and periodically use a tool to scrape away tartar. More than four decades in, I have all my teeth, and just one filling. ---
**Author:** ![DSeid](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dseid/32/20194_2.png) [@DSeid](https://boards.straightdope.com/u/DSeid)\ **Post date:** [August 11, 2019, 6:48pm UTC](https://boards.straightdope.com/t/medical-benefits-of-dental-floss-unproven-what-about-fluoride/838416/20 "2019-08-11T18:48:29Z")
Why is the question actually worth asking? From the article linked to in the op - > [@](#): > > Even companies with a big market share of the flossing business — by next year, the global market is predicted to reach almost $2 billion, with half in the United States, according to publisher [MarketSizeInfo.com](http://MarketSizeInfo.com) — struggled to provide convincing evidence of their claims that floss reduces plaque or gingivitis. Yet the industry has paid for most studies … Yes. That reads $2 BILLION a year … half of it in the United States. And of course the value of the time. A minute or two every day doing something you do not enjoy. Roughly 4 hours of unenjoyable time per year. $2 billion a year spent for something that adds significant quality-adjusted years of life could be money very well spent. But if it actually doesn’t do anything, other than waste your time and money? No question a prospective randomized controlled trial (RCT) powered sufficiently to fairly definitively answer the question would be expensive. But again a cohort study (even a case control study\* controlling for known confounders) would be not too hard or too expensive to do. It could be piggybacked into something like the [Nurse’s Health Study](https://en.wikipedia.org/wiki/Nurses%27_Health_Study) fairly easily or done on its own. The quality of evidence of cohort and case control studies is not on the level of a prospective RCT but it is still pretty good. And again given that, my guess is that the industry has indeed done such studies, gotten the answer but not the one they wanted, and sat on it. \*Identify populations with and out periodontal disease, match for known confounders and characteristics, and determine if rates of never vs daily flossing in the past are significantly different in those with and without that outcome. [Next page](https://boards.straightdope.com/t/medical-benefits-of-dental-floss-unproven-what-about-fluoride/838416.md?page=2)