Flossing might not be as important to your daily dental hygiene as your dentist told you.
The government has recommended flossing for more than 35 years, starting with a surgeon general’s report in 1979. In 1990, it was added to the Dietary Guidelines for Americans. By law, the recommendations in the document have to have scientific evidence. But in the 2015-20 edition released this year, flossing was nowhere to be found.
In fairness, tooth brushing also doesn’t appear in the current guidelines, which focus on cutting sugar to help dental health. But the MIA floss recommendations have started a conversation about how necessary the daily habit really is. In a letter to the Associated Press, the government said the benefits of flossing hadn’t been sufficiently researched. As it turns out, the current evidence on the value of flossing is mixed.
One 2015 report in the Journal of Clinical Periodontology concluded that studies haven’t adequately shown that floss is successful at removing plaque or reducing gum inflammation.
Another 2011 Cochrane review of 12 studies compared the benefits of daily tooth brushing and flossing to brushing alone. The authors found that regular flossers were less likely to have inflammation from gingivitis than those who only brushed. Gingivitis is mildly irritating but can lead to periodontitis, a serious infection that destroys the bone supporting your teeth. But the review found weak evidence to show flossing helped reduce plaque, which is a benefit dental experts often cite. Plus, the authors said the studies were overall unreliable.
The American Dental Association and the American Academy of Periodontology sent studies supporting the benefits of flossing to AP, but even those weren’t solid. Some tests only lasted a couple weeks (periodontitis takes years to develop), while others used out-of-date methods or didn’t track enough volunteers to make conclusive claims.
The issue could be that people just don’t know how to floss well.
A 2006 review in the Journal of Dental Research found that kids whose teeth were flossed by professionals on school days for 1.7 years reduced their risk of cavities by 40 percent. But the authors also found research showing that students who flossed by themselves for two years didn’t have the same cavity protection.
The ADA says the correct way to floss is by guiding the floss up and down against the sides of the teeth—not just sawing back and forth over the same spot.
In a statement, the American Academy of Periodontology acknowledged a lack of solid research: “Much of the current evidence does not utilize a large sample size or examine gum health over a significant amount of time. Additionally, many of the existing studies do not measure true markers of periodontal health such as inflammation or clinical attachment loss.”
Until better evidence comes out, the organization encourages patients to keep flossing in their daily routines.
“It’s low risk, low cost,” National Institutes of Health dentist Tim Iafolla told AP. “We know there’s a possibility that it works, so we feel comfortable telling people to go ahead and do it.”