Is there anyone more reliably smug than a person who actually flosses the recommended amount? Somehow, routinely dredging up unidentifiable morsels of past meals from between their teeth gives people a sense of self-righteousness that they feel find about lording over the rest of us more casual, shit-I’m-going-to-the-dentist-soon-better-start-flossing flossers. According to a new report from the Associated Press, though, the scaffolding upon which flossers have built their reigns of hygienic superiority is “‘weak, very unreliable,’ of ‘very low’ quality, and carries ‘a moderate to large potential for bias.’”

Advertisement

A year ago, the AP began pursuing the scientific evidence legally required to support years of the government’s flossing recommendation, dating back to a 1979 Surgeon General’s warning. The AP’s Jeff Donn—a man who presumably does not floss with particular regularity, but whom we can infer is surrounded by pushy people who do—writes that the news organization ultimately issued a Freedom of Information Act request to the departments of Health and Human Services and Agriculture. Then this happened:

When the federal government issued its latest dietary guidelines this year, the flossing recommendation had been removed, without notice. In a letter to the AP, the government acknowledged the effectiveness of flossing had never been researched, as required.

Data on flossing does exist, it’s just not all that encouraging or conclusive. A review of 25 relevant studies found small sample sizes, outdated methods, and irrelevant results supporting the established wisdom that flossing helps prevent cavities and gum disease. Even studies funded by companies that stand to directly benefit from increased pressure to floss—members of the roughly $2 billion global floss market—“struggled to provide convincing evidence of their claims that floss reduces plaque or gingivitis.”

Advertisement

While liberating, this news is intuitively baffling. Even a single instance of flossing seems to have a noticeable impact on the amount of debris in your mouth, which must be good for something, right? When confronted with the lack of substantial evidence, though, experts questioned offered only that people in the studies were flossing wrong (too much back and forth, not enough up and down), or else were not naturally of high enough risk for gum disease for there to be a measurable impact.

Even after acknowledging such a recommendation is based on specious support, most of the dentists interviewed maintained that people should floss. (“It’s low risk, low cost,” offered National Institutes of Health dentist Tim Iafolla.) As the AP has it, though, “Floss can occasionally cause harm.” Stick things between your teeth at your own risk.