Tossing flossing?

Robert H. Shmerling, MD
Robert H. Shmerling, MD, Faculty Editor, Harvard Health Publications

The burning question in the news last week was this: should you bother flossing?

The answer for decades has been “of course.” And it’s likely you’ve heard something similar from your dentist. I know I have.

But, while the importance of flossing may have been widely accepted, the evidence supporting it turns out to be surprisingly thin. At least that’s the conclusion of health experts who developed the recently released Dietary Guidelines for Americans, 2015-2020. These guidelines are issued every five years by the U.S. Department of Health and Humans Services and the U.S. Department of Agriculture “…to reflect the current body of scientific evidence on nutrition, food, and health.” The 2010 edition included this sentence:

“A combined approach of reducing the amount of time sugars and starches are in the mouth, drinking fluoridated water, and brushing and flossing teeth, is the most effective way to reduce dental caries.”

But, the latest edition leaves this sentence out. That’s because the authors of these guidelines could not find convincing evidence to support flossing, and the guidelines are supposed to be evidence-based. According to reviews of the evidence published in 2011 and 2015, there is minimal, short-term, and generally unreliable evidence that flossing might reduce gum inflammation, but no convincing evidence that it promotes plaque removal or prevents tooth decay or dental caries (cavities).

Is the lack of evidence for flossing big news?

I’ve seen several eye-grabbing headlines regarding this development, including:

  • “Feeling Guilty About Not Flossing? Maybe There’s No Need” (New York Times)
  • “Guilty No More: Flossing Doesn’t Work” (Mother Jones)
  • “A big problem with flossing” (CBS News)

It is surprising to learn that there is so little evidence to support such a well-accepted bit of health dogma. Yet, there may be less here than meets the eye.

In fact, I think these headlines (and some of the comments I’ve heard from friends and family) miss the mark on this flossing kerfuffle. There’s a saying in the science world that “absence of proof isn’t proof of absence.” That is, just because the evidence isn’t there doesn’t mean an idea is wrong. Unproven is unproven, not disproven!

A cousin emailed me to say “Good, now I can feel less guilty about not flossing.” I’m all for people feeling empowered with their health decisions (especially if they are well-informed). But the experts who removed the flossing recommendations from the dietary guidelines did not find flossing was useless. They only found that flossing had never been well-studied and that the evidence to date was inconclusive. If my cousin has gum disease, flossing might be important for his oral health. Flossing is low-cost, low-risk, and has potential (and biologically plausible) health benefits; it seems premature to conclude it is useless. In fact, it may very well be a good idea just waiting to be well-studied.

Flossing in the dietary guidelines? What about brushing?

And am I the only one that finds it odd that flossing was even mentioned in a compilation of dietary guidelines? They are supposed to be about what you eat, not how you care for your teeth! And where is the outrage about brushing? That was removed as well but no one seems to be worrying much about that; perhaps it’s because people don’t mind brushing as much as they mind flossing. In fact, a 2015 survey found that 14% of respondents would rather clean a toilet than floss their teeth each day.

So to floss, or not floss (without guilt)?

The obvious next step is to recommend that researchers study the health impact of flossing. With a well-funded, well-designed study, it may be easy to prove that, in fact, flossing is good for your oral health, and I would not be surprised if it turned out to be good for you in other ways, since gum disease has been linked to an increased risk of cardiovascular disease, diabetes, and stroke. But that’s getting ahead of the story; let’s first prove that daily flossing is at least good for your oral health. I’m not going to wait for the research; I’m going to keep flossing. I hope my cousin does too.

Related Information: Harvard Men’s Health Watch

Comments:

  1. Maria Jasmine Freeman

    I was never a fan of flossing, many as scienctific recommendations were in that context, and many as my relatives were who floss. I always argued to myself that may be more flossing in between teeth creates more space for more food particles- and so for tooth- picks, creating a vicious cycle!! I am a great fan of brushing though, never missing on it anytime, and taking my time on it! I am sixty two, a mother, and have only 2 tooth fillings-thank God, though with little gingival recession, with all teeth healthy and there! Mind you, I eat only v little meat, no soft drinks, no sugar-of any source, take a lot of nuts, whole grains, beans, veggies, and adequate fruits( with their skin), and some cheese and yoghurt, and olive oil. More, I have been fasting DAILY for more than eight years at a stretch, with only one late evening meal; this certainly saved me a lot of tooth trouble( and more)!
    Therein my strategy seems not wrong! Thanks!!
    Dr Hana Fayyad, pediatrician( Maria Jasmine Freeman, published author, on menopause).

  2. dor cohen

    I was recommended this blog by way of my cousin. I’m not certain whether or not this publish is written through him as nobody else realize such specified approximately my difficulty. You are incredible! Thank you!

  3. carin

    I have heard this same comment “to not floss” at various biological medicine conferences because it drives the bacteria deeper. In the ancient tradition of ayurvedic medicine ‘oil pulling’ greatly improves gum health, reduces bacteria, and whitens teeth!

  4. Ed

    I have substituted the moderately flexible “inch-long-ribbon-on-a-pick” for the traditional and cumbersome “long-rope-in-a-box” floss technique with good results. No more snipping a long length and wrapping ends around fingers and then struggling to maneuver fingers around the mouth at proper angles. As someone has mentioned – cleaning a toilet seems more attractive. I’m surprised no one has mentioned this alternative.
    If I am missing something, please let me know.

    • Nancy

      Ed, I hope that you are not among those who discard their floss pick on the ground outside. They are ubiquitous. Come on flossers, use the trashcan.

      • Ed

        Hi Nancy – don’t think I have done that yet, but now consider myself duly pick-alerted😊.
        I trust you will also extend your alert to potential disposers of those wasteful, soggy bacteria-laden 8-inch lengths of tooth rope. Regards, Ed

  5. Bill Heronemus

    I have been using a water-pik for many years with similar results that I previously got from flossing. I’m wondering what studies may have been made comparing the two methods.

  6. Barbara Russell

    I went from having new cavities every year in my 20s to NO cavities ever again, and the only thing that changed was that I began to floss daily, thanks to a dental hygienist who talked to me about the importance of flossing. I am in my 60s now, and have been told I have excellent gum health. I don’t need further research to prove the benefits of flossing. What concerns me is that these kinds of headlines will undermine decades of progress in oral health as people abandon flossing, not bothering to read the details of the research.

  7. Raymond Bandar

    It is only natural to feel the good reason for flossing.
    From time immemorial, our elders, now I am one of those elders, always poked their teeth to remove food particles stuck in the teeth: The Toothpick.
    Rarely an old health tradition has proven to be wrong.
    I will continue “Flossing”

  8. Derek Nelson

    As a dentist, I offer one comment to my patients… “If ,when you floss the floss does not smell then you have my permission not to floss ever again” I rest my case and remain grateful to all those who follow our advice. Just don’t try and tell us that all the rotten debris between unflossed teeth has no effect on bad breath. Let’s face it one can prove almost anything if you set out to do so … Makes one wonder what the supposed academics are going to come out with next

    • Freshy

      Amen! If I skip a day of flossing my mouth tastes bad and the gunk I scrape from between my teeth smells rotten. If I floss daily it doesn’t smell nearly as bad.

      I find the unwaxed floss does the best job of scraping off the biofilm and even scrapes appreciable gunk off parts of my teeth normally accessible by toothbrush. So I actually floss first and then brush. My teeth feel much cleaner and smoother with this regimen than when I brush-first-floss-second. I then scrape my tongue with the used floss and am amazed by the stuff that I spit out into the sink after scraping my tongue in this manner.

      My breath is so much better since starting this regimen and I sleep better with a cleaner tasting mouth.

  9. E TAL

    When I was in my thirties, the shocked dental hygienist refused to take care of my teeth when she discovered the depth of my gum pockets. After treatment and gum operations, my periodontist taught me a few simple procedures including flossing to carry out every evening.
    Over thirty years later, I still have all my teeth and have never had a cavity since. I visit a dental hygienist every three months, floss every night, clean around my gums with a toothpick in a hand held device and “inject” a medicated gel into the worst pockets. It takes no more than three minutes and I am certain has saved me much pain, expensive dental treatments and my teeth. What more proof do I need?

    • Colette

      I will consult my pharmacist to find out about this “medicated gel” that you referred to, unless of course you can steer me in the right direction . However, more practical information I need from you is…how do you “inject” it?

  10. mikereeve

    Nobody likes to be told that some advice they have relied on for years and practiced has no actual scientific basis, even if only because nobody has bothered to study it rigorously. There are millions of supplements with scientifically unproven claims lining the shelves in CVS, Costco etc. e.g. “supports healthy liver function…..”. You can’t afford to buy them all in the hope that they may be effective because theyhave not actually been proved ineffective.

    Get over it (including Robert Schmerling). Makes me wonder why I subscribe to Harvard Health for objective science reporting and advice.

  11. Tim Maguire

    When you floss a piece of fish out of you gums after less than a day, and your gum bleeds from the irritation, you know flossing helps.

  12. Jerry Amos

    We eat vegetables in variety. Corn, celery, all sorts get stuck between my teeth. ouch. Brush, then lots of stuff still stuck. Floss is the only way – toothpicks and such don’t cut it.

    I have “pockets” at the gum line between my teeth. With careful brushing, flossing, and a denticator I’ve been able to keep the pockets from getting worse. The Peridontist wanted to remove a molar ten years ago, but I’ve been able to keep the pocket from getting worse with brushing and flossing, and the tooth is working fine.

    Now I didn’t study the “flossing isn’t useful for cavities” in detail, how about cavities at the gum line where the toothbrush can’t reach, but floss can?

    With flossing, I’m able to clear out the vegetable residue that the brush cannot and keep my gum line healthy.

  13. sunnyaria

    The first thing that comes to my mind is, why have dentists been recommending flossing when it is not an evidence based technique for preventing dental disease. The second thing that comes into my mind is, why are we being told that flossing may not make a difference. Well, if it does, then dentists will make a lot more money because there will be more gum disease, and decay. There are so many ridiculous well funded research programs performed and published. This whole issue seems really fishy to me.

  14. Paul Bottone DDS

    Clean teeth do not decay and healthy gums saves teeth and lives.
    As you get older food particles accumulate at the gum line. Sorry just a fact of life. Tooth picks, interdental stimulators, Floss with a naught in it to pull out debris, are a must. 2 minutes home care will not save your teeth or gums as you get older. My patients and I can attest to that. Unfortunately I fought a losing battle with my nursing home patients as they grew older or dementia set in. These researchers need to do their studies in county hospitals with dental clinics or in dental school clinic for a real example of most of our population.

  15. marilyn locke

    i think what they are advocating about not flossing, is a travesty!! do you know the amount of food i scrape off between my teeth AFTER BRUSHING for 20 minutes?????????? i am very anal about my teeth and gums AFTER losing another tooth due to the lack of flossing!! my teeth and gums are pink and healthy, thanks to flossing!!!!! infact, if i have no time to brush, i will floss and am very confident my teeth and gums are clean…so yall go ahead and listen to these idiotic morons about NOT FLOSSING, and see if you dont lose any teeth between now and then, or have tooth pain for the lack of thereof, and dont say i didnt try to warn you!! no thanx, i’ll keep on flossing EVERYDAY for the rest of my life!!! signed,,,,,,,healthy gums and lovin’ it!!!!!!!!!!! NO MORE TOOTH PAIN!!

    • ramona silvestri

      ya the research was done by the company that makes crowns and caps how convenient $$$$$ Like a research company sponsored by a tobacco company “guess what folks cigarettes do not cause cancer no not at all!”
      $$ee You later

      • James

        Hi Ramona,

        I noted this in a former comment; thanks and cheers…
        IF it is strongly scientifically verifiable that food particles indefinitely stuck between teeth cause tooth decay, cavities, and gum disease;
        AND IF that is strongly scientifically verifiable that this is a main reason tooth brushing is good;
        AND IF is is self-evident (which it is) that flossing removes food particles stuck between teeth which brushing can’t remove and therefore would stay there indefinitely without flossing,
        THEN it is has ALREADY been demonstrated that flossing, by removing those tooth particles stuck between teeth, helps prevent tooth decay, cavity, and gum disease.
        Unless one can refute the logic… : )

        Thanks and respects and regards and cheers…

      • SMB

        Have you ever taken Tylenol for a headache? Advil? Aspirin? The research on these medications was entirely funded by the pharmaceutical companies that manufacture them. That is how a product gets to the marketplace. Industry-funded does not always mean the product does not have merit, is harmful, or is a hoax. Aspirin is considered an indispensable medication according to the World Health Organization and in order for it to get to market, Bayer had to spend hundreds of thousands of dollars to research, develop, produce, and market it. That is how the world works.
        As for flossing, there is very good evidence on its efficacy in studies done on twins. Unfortunately, the Cochrane Reviews do not include any twin study data, whether medically-or dentally-related. Cohorts of twins are the ideal population to perform clinical trials in. It is too bad that the media did not report this important fact.

  16. Scotty

    Flossing is hard and I did it for years. Then I found go-betweens, the little brushes that go between the teeth. They are a lot easier to use so I do it 2 or 3 times a day and quit flossing. In my opinion, at least for me, they do a better job than flossing. There has been no deterioration in my teeth or gum health since I made this change.

    • James

      Scotty that’s a good comment and I’d agree. I’d just call those little brushes that we insert between our teeth to be just another form of flossing, and based on the same logic and common sense evidence of it removing food particles stuck between teeth as flossing, and that the same irresponsible sensationalists would say there hasn’t been “scientific evidence” for these little brush inserts either. When it’s basically the same thing as flossing and based on the same logic and common sense (as in my comment just before yours.) Thanks for posting; and I agree…

  17. James Adler

    This seems ridiculous.
    It was such obvious common sense it never needed checking.
    IF it is strongly scientifically verifiable that food particles indefinitely stuck between teeth cause tooth decay, cavities, and gum disease;
    AND IF that is strongly scientifically verifiable that this is a main reason tooth brushing is good;
    AND IF is is self-evident (which it is) that flossing removes food particles stuck between teeth which brushing can’t remove and therefore would stay there indefinitely without flossing,
    THEN it is has ALREADY been demonstrated that flossing, by removing those tooth particles stuck between teeth, helps prevent tooth decay, cavity, and gum disease.
    So this entire issue is classic merely debased sensationalism and absurd.

  18. Allan Jones

    None of the comments have mentioned that the studies in favour of flossing have been paid for by the “big flossing” interests – those who manufacture the dental floss. One should be very circumspect of results in favour of a finding for which the “studies” have been paid for largely, if not only, by the manufacturers of that product. Of course flossing is beneficial – more so to the manufacturers’ bottom line rather than my teeth!

  19. Ann Smith

    FLOSSING SHOULD BE A DAILY REQUIREMENT BECAUSE WE WERE TOLD THAT IT IS RELATED TO HEART DISEASE.

  20. susan richmond

    Hygienists abjured me to floss. I continued to have decay until I started doing following their advice. Haven’t had any since I took it up on a regular basis. For me, the proof is overwhelming. My contacts are so tight that until the modern slippery type the floss always got stuck. Sometimes things do get better. – Coffee, bread, floss …

  21. CZ

    The first time flossing removes a chunk of residue, that would otherwise rot in place, should be sufficient to convince anyone.

  22. Terry Goldman

    The study referred to in the NYT was flawed: It compared brushing only to brushing and flossing, but did not include a flossing only cohort. (Not to mention a doing nothing cohort, but that might have been unethical much as a control is always necessary.)

  23. Jim

    I started flossing regularly a few years ago when an annoying gap between two of my teeth started to collect food. The food irritated my gums and HURT. So I started flossing and, yes, the poor state of my gums meant some bleeding at first. But a week later, almost no blood. My gums feel great. Cleanings at my dentist became much easier. There’s no doubt flossing is good for gum health. And oral health is connected in still unknown ways to general (and especially heart) health. Why wouldn’t you do it? It takes 30 seconds a day.

  24. Peter strock

    I forgot: chronic bad breath can be the sign of upper respiratory disease or other systemic diseases. It may be worth consulting your physician.

  25. Peter Strock

    What is more dangerous than a dog bite? A human bite, because of the pathogens that are normally present in the mouth.

    1. If your gums bleed when you floss or brush either you are too vigorous or you have inflammed gums. I.e. disease. See your dentist. Your gums should NOT bleed if they are healthy.
    2. A toothpick is a poor substitute and can do harm if used too vigorously. There are very effective aids to reach material trapped between the teeth. Ask your dentist.
    3. Anything that helps remove placque -even flossing- is beneficial
    4. Fluoridation of drinking water – when done properly – is probably the single most effective public health initiative ever undertaken. There are more than 3 generations of families in Newburg NY with benefits from the concept. The outcome has been intensely studied over 60+ years. There are some legitimate concerns but they are trivial compared to the benefits.
    5. Bad breath after brushing means that material which is decomposing has been left .
    6. Frequently overlooked is the need to brush the tongue. Lot’s of “stuff” remains in the recesses of the tongue, which is not smooth as it appears.

    7. Consider all the above the next time you plan to kiss a loved one. (:-)

  26. Peg Herlihy

    And those who don’t floss have terrible bad breath even after brushing. Those stubborn food particles can sit embedded between teeth and cause you to want to offer someone a breath mint. Please don’t discourage flossing. It has its merits.

  27. LISBET TAYLOR

    What about the “drinking fluoridated water” phrase in the new recommendation?? THAT jumped out at me immediately! No one seems to be talking about the harmful effects of fluoride…

  28. Jacob Grill

    Every people want to live in healthy life.But we should know about healthy living.Without good health,anyone can not become happy.Thanks for this helpful post.

  29. HSDM

    Where are the HSDM Faculty opinions?

  30. Jim Bay

    I’ve avoided flossing my whole life. I found it uncomfortable, it made my gums bleed, and as a young man, I could see little benefit that I couldn’t get more easily with a toothpick.

    Two things have changed my mind. One, my saliva production is impaired, and nature’s natural mouthwash is not adequate to remove bits of food that linger longer. Likewise, maturity has brought many changes to my mouth, and made thorough cleaning more difficult.

    I now find that flossing literally does make my teeth feel cleaner! The dilemma for me is that my mouth might be in better shape had I flossed when younger – but then I may never have realized the benefits as I do now.

    Unfortunately, like smoking, the effects aren’t apparent until its too late to do anything about them, which might help explain the enduring nature of that “dogma” that’s been passed down over the years.

    • Rachel Mascord

      Hi Jim,
      I have worked as a dentist for more than 25 years, and I must say that it is never too late to benefit from flossing. OK, flossing cannot wind back the clock on the damage done, but the changes to oral and overall health made by flossing are substantial, and make it a very valuable thing to do.
      What this story highlights is that we are always seeking ways to get ourselves off the hook of responsibility for taking care of our bodies – and this very reckless use of science is just one example of the way we try to avoid what we need to do.
      You have shared the practical reality of the benefits of flossing from your experience. And people do need to hear that. As a dentist, I can describe the benefits to my patients, but it is experiences like yours that can really make the difference and perhaps get through to people in a way that I as a professional cannot.

      • Margaretanne

        May I just say that a large percentage of people, including me, can’t afford to see a dentist. God forbid you have a dental problem. I know how important dental health is but what does one do with limited income. So, it is vital that you take care and be diligent with your own health. Otherwise, be prepared for sticker shock. : {