Is Flossing A Waste of Your Time? The Federal Government Isn't Sure

Nearly everyone accepts that flossing every day is an important part of oral health, and most of those people would probably admit that they don't floss enough. But as the Associated Press reported Tuesday, we should be much less confident in this dental orthodoxy than we are. In fact, there's little to no scientific evidence that flossing is all that good for you.

Of course, don't expect your dentist to tell you that. The American Dental Association recommends daily flossing, and dentists across the country follow suit.

So did the nutrition guidelines produced by the departments of Agriculture and Health and Human Services. That is, until now.

The daily flossing recommendation was unceremoniously stricken from the guidelines this year. In a note to the AP, the government agencies admitted that "the effectiveness of flossing had never been researched, as required."

Others have pointed out previously that flossing is supported by weak, at best, evidence. In 2013, Ross Pomeroy of Real Clear Science found that the high-quality research that does exist on flossing, such as a review of 12 relevant studies from the Cochrane Library, casts doubt on the benefits. While the study found that flossing in addition to brushing reduced gingivitis, it found little evidence of a reduction in plaque and/or the occurrence of cavities.

"Overall, current scientific knowledge suggests that flossing simply isn't as vital as dentists make it out to be," Pomeroy wrote.

One study did find a significant reduction in cavities for students who were routinely flossed by dental professionals. However, these kids appear to have had poor tooth brushing skills and minimal access to fluoride. These considerations, in addition to the fact that few of us have access to routine flossing by professionals, make the study's findings far from conclusive.

Much of the evidence cited by dental professional groups and manufacturers of oral hygiene products in support of flossing is surprisingly weak. The studies frequently contain few subjects or a very short time period. And though some of this research does suggest that flossing removes plaque and food matter, it provides little support for the long-term benefits of flossing.

The AP also pointed out that floss can occasionally cause damage to gums, teeth and dental work, and potentially push around harmful bacteria, though it's not clear how serious these risks are.

Experts who spoke to the AP and the New York Times suggested that most people might not be effectively flossing their teeth — this would explain why the research is inconclusive. If people are just slipping the floss in between their teeth, rather than wrapping it around the sides and sliding it below the gum line, as recommended, they may receive minimal benefits.

But if that's true, it still suggests that the guidelines should be revised and require further study, because just telling people to "floss daily" is ineffective.

The American Dental Association pushed back Tuesday against the reports of the AP and other outlets, writing, "Although recent news reports have questioned the benefits of cleaning between your teeth, using an interdental cleaner (like floss) is an essential part of taking care of your teeth and gums."

However, it provided no response to the factual claims made by the AP and others, and it offered no evidence to support these claims in its press release on the matter. In a phone call with Patch, spokesman Dr. Matthew Messina for the ADA acknowledged there was little high-quality evidence for the long term benefits of flossing, but he argued that the cumulative experience and opinions of dentists strongly support the association's current flossing recommendations.

So, should we throw away the floss and never look back? Unfortunately, it seems that the jury is still out on that question, and we'll have to wait until there's better research before we get a a definitive answer. Messina said that the increased media attention to this question may inspire more rigorous study of the effects of flossing.

This story has been updated to include comments from the ADA.

Photo credit: Smabs Sputzer via Flickr