For many, taking the time to floss every day is a bother. But for dentists, taking the time to properly research flossing over the course of a century is apparently even more inconvenient.

Despite being dentist-recommended since the early twentieth century, researchers have yet to conduct sufficient, reliable studies to support the claim that flossing effectively prevents cavities and gum disease.

This stain on the dental profession was spotted last year when the Associated Press asked federal agencies for the data behind its recommendation that Americans floss. After the AP filed Freedom of Information Act requests, the government opened up and admitted that it didn’t have adequate data to back the recommendation—something it is required to have by law.

The US Agriculture and Health and Human Services departments quietly removed the flossing recommendation from the latest version of dietary guidelines.

Since doctors began saying that a string-based tooth scraping was good for oral health, a handful of studies have been conducted. However, they all fall far short of what’s needed to make a convincing argument. A 2011 review of a dozen randomized controlled studies concluded that, “Overall there is weak, very unreliable evidence which suggests that flossing plus toothbrushing may be associated with a small reduction in plaque at 1 or 3 months.”

Other studies only looked at oral health over shorter periods of time, such as two weeks, which is not enough time for cavities or gum disease to develop.

Still, many dentists will continue to recommend flossing for removing debris between your chompers. "It's low risk, low cost," National Institutes of Health dentist Tim Iafolla told CNBC. "We know there's a possibility that it works, so we feel comfortable telling people to go ahead and do it."