I got an interesting reader question a few days ago, in the form of a rather perplexed/angry/tentatively excited message asking if he could stop flossing. The asker (who shall remain nameless) was reacting to a story from the Associated Press called “The Medical Benefits of Dental Floss Unproven“.  In it, the AP tells their tale of trying to find out why the government was recommending daily flossing, given that it appeared there was no evidence to support the practice. They filed a Freedom of Information Act request, and not only did they never receive any evidence, but they later discovered the Department of Health and Human Services had dropped the recommendation. The reason? The effectiveness had never been studied. Oops.

So what do you need to know about this controversy? Is it okay to stop flossing? Here’s 5 things to help you make up your mind:

1. The controversy isn’t new. While the AP story seems to have brought this issue in the public eye, it’s interesting to note that people have tried to call attention to this issue for a few years now. The article I linked to is from 2013, and it cites research from the last decade attempting to figure out if flossing actually works or not. While flossing has been recommended by dentists since about 1902 and by the US government since the 1970s, it has not gone unnoticed that it’s never been studied.
2. The current studies are a bit of a mess. Okay, so if everyone kinda knew this was a problem, why hasn’t it been resolved? Well it turns out it’s actually really freaking difficult to resolve something like this. The problem is two-fold: people hate flossing and flossing is hard to do correctly. Some studies have had people get flossed by a hygienist every day, and those folks had fewer cavities. However, when the same study looked at people who had been trained to floss themselves, they found no difference between them and those who didn’t floss. Many other studies found only tiny effects, and a meta-analysis concluded that there was no real evidence it prevented gingivitis or plaque build up. Does this require more time investment? Better technique? Or is it just that conscientious people who brush are pretty much okay either way? We don’t actually know….thus the controversy.
3. Absence of evidence isn’t evidence of absence. All that being said, it’s important to note that no one is saying flossing is bad for you. At worst it may be useless, or at least useless the way most of us actually do it.  However, most dentists agree that you need to do something to remove bacteria and plaque from between your teeth, and that shouldn’t be taken lightly. It’s absolutely great for people to call out the American Dental Association and the Department of Health and Human Services for recommendations without evidence, but we shouldn’t make the mistake of believing that this proves flossing is useless. That assertion also has no evidence.
4. Don’t underestimate the Catch-22 of research ethics. Okay, so now that everyone’s aware of this, we can do a really great rigorous study on this right? Well…maybe not. Clinical trial research ethics dictate that research should have a favorable cost benefit ratio for participants. Since every major dental organization endorses flossing, they’d have to knowingly ask some participants to do something they actually thought was damaging to them. That would be extremely tough to get by an Institutional Review Board for more than a few months. This leaves observational studies, which of course are notorious for being unable to settle correlation/causation issues and probably won’t end the debate. Additionally, some dentists commenting are concerned about how many of the limited research dollars available should be spent on proving something they already believe to be true. None of these are easy questions to answer.
5. There may not be a precise answer. As with many health behaviors, it’s important to remember that flossing isn’t limited to a binary yes/no. It may turn out that flossing twice a week is just as effective as flossing every day, or it may turn out they’re dramatically different. There’s some evidence that using mouthwash every day may actually be more effective than flossing, but would some of each be even better or the same? Despite the lack of evidence for the “daily” recommendation, I do think it’s worth listening to your dentist on this one and at least attempting to keep it in your routine. Unlike oh, say, the supplement industry, I’m not really sure “Big Floss” is making a lot of money on the whole thing. On the other hand, it doesn’t appear anyone should feel bad for missing a few days, especially if you use mouthwash regularly.

So after reviewing the controversy, I have to say I will probably keep flossing daily. Or rather, I’ll keep aiming to floss daily because that has literally never translated in to more than 3 times/week. I will probably increase my use of mouthwash based on this study, but that’s something I was meaning to do anyway.  Whether it causes a behavior change or not though, we should all be happy with a push for more evidence.