Dr. Wayne Aldredge, president of the American Academy of Periodontology, demonstrates how dental floss should be used in Holmdel, N.J. Aldredge says many people use floss incorrectly, moving it in a sawing... (Associated Press) 
 
 HOLMDEL, N.J. (AP) — It's one of the most universal recommendations in all of public health: Floss daily to prevent gum disease and cavities. 
 
 Except there's little proof that flossing works. 
 
 Still, the federal government, dental organizations and manufacturers of floss have pushed the practice for decades. Dentists provide samples to their patients; the American Dental Association insists on its website that, "Flossing is an essential part of taking care of your teeth and gums." 
 
 The federal government has recommended flossing since 1979, first in a surgeon general's report and later in the Dietary Guidelines for Americans issued every five years. The guidelines must be based on scientific evidence, under the law. 
 
 Last year, the Associated Press asked the departments of Health and Human Services and Agriculture for their evidence, and followed up with written requests under the Freedom of Information Act. 
 
 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. 
 
 The AP looked at the most rigorous research conducted over the past decade, focusing on 25 studies that generally compared the use of a toothbrush with the combination of toothbrushes and floss. The findings? The evidence for flossing is "weak, very unreliable," of "very low" quality, and carries "a moderate to large potential for bias." 
 
 "The majority of available studies fail to demonstrate that flossing is generally effective in plaque removal," said one review conducted last year. Another 2015 review cites "inconsistent/weak evidence" for flossing and a "lack of efficacy." 
 
 One study review in 2011 did credit floss with a slight reduction in gum inflammation — which can sometimes develop over time into full-fledged gum disease. However, the reviewers ranked the evidence as "very unreliable." A commentary in a dental magazine stated that any benefit would be so minute it might not be noticed by users. 
 
 The two leading professional groups — the American Dental Association and the American Academy of Periodontology, for specialists in gum disease and implants — cited other studies as proof of their claims that flossing prevents buildup of gunk known as plaque, early gum inflammation called gingivitis, and tooth decay. However, most of these studies used outdated methods or tested few people. Some lasted only two weeks, far too brief for a cavity or dental disease to develop. One tested 25 people after only a single use of floss. Such research, like the reviewed studies, focused on warning signs like bleeding and inflammation, barely dealing with gum disease or cavities. 
 
 Wayne Aldredge, president of the periodontists' group, acknowledged the weak scientific evidence and the brief duration of many studies. In an interview at his private practice in New Jersey, he said that the impact of floss might be clearer if researchers focused on patients at the highest risk of gum disease, such as diabetics and smokers. 
 
 Still, he urges his patients to floss to help avoid gum disease. "It's like building a house and not painting two sides of it," he said. "Ultimately those two sides are going to rot away quicker." 
 
 Aldredge also said many people use floss incorrectly, moving it in a sawing motion instead of up and down the sides of the teeth. Pressed about the origins of his organization's endorsement of flossing, he said it may simply have "taken the ADA's lead." 
 
 When the ADA was asked for proof of its claim that flossing helps prevent early gum disease and cavities, the group cited the 2011 review and a 2008 two-week study that measured bacteria and did not even consider gum disease. 
 
 In a later statement to the AP, the ADA said flossing "removes plaque" and "is proven to help remove" debris from between teeth. A video on its website proclaims that flossing "helps prevent gum disease." When pressed, Matthew J. Messina, a practicing dentist and spokesman for the dental association, acknowledged weak evidence, but he blamed research participants who didn't floss correctly. 
 
 Even companies with a big market share of the flossing business — by next year, the global market is predicted to reach almost $2 billion, with half in the United States, according to publisher MarketSizeInfo.com — struggled to provide convincing evidence of their claims that floss reduces plaque or gingivitis. Yet the industry has paid for most studies and sometimes designed and conducted the research. 
 
 Procter & Gamble, which claims that its floss fights plaque and gingivitis, pointed to a two-week study, which was discounted as irrelevant in the 2011 research review. 
 
 Johnson & Johnson spokesman Marc Boston said floss helps remove plaque. When the AP sent him a list of contradicting studies, he declined comment. 
 
 The floss-making companies partner with the ADA through its Seal of Acceptance program. The ADA promotes the seal to companies as something that "directly affects the purchase decisions of consumers;" each manufacturer is charged $14,500 for the evaluation. If it approves the product, the ADA then charges an additional annual fee of $3,500. 
 
 The ADA says it rigorously evaluates products and makes no profit from the program. However, floss companies themselves are allowed to design the studies. 
 
 "The funding can come from companies — no problem at all," said dentist Marcelo W.B. Araujo, vice president of the ADA's Science Institute, who joined the organization after serving as an executive for Johnson & Johnson. "The design can start from the company." 
 
 When flossing first gained acceptance, no proof was required of remedies. Dentist Levi Spear Parmly is credited with inventing floss in the early 19th century. By the time the first floss patent was issued, in 1874, the applicant noted that dentists were widely recommending its use. 
 
 The ADA has been promoting floss universally since 1908. "They just looked into what they did every day in their clinical practice and what they would recommend for patients," said Araujo. 
 
 Count dentist Damien Walmsley, scientific adviser to the British Dental Association, among the skeptics. "It's important to tell people to do the basics. Flossing is not part of the basics." 
 
 Floss can occasionally cause harm. Careless flossing can damage gums, teeth and dental work. Though frequency is unclear, floss can dislodge bad bacteria that invade the bloodstream and cause dangerous infections, especially in people with weak immunity, according to the medical literature. 
 
 National Institutes of Health dentist Tim Iafolla acknowledged that if the highest standards of science were applied in keeping with the flossing reviews of the past decade, "then it would be appropriate to drop the floss guidelines." 
 
 Regardless, he added, Americans should still floss. 
 
 "It's low risk, low cost," he said. "We know there's a possibility that it works, so we feel comfortable telling people to go ahead and do it." 
 
 ___ 
 
 The AP National Investigative Team can be reached at investigate@ap.org 

 Me to you: AP 
 
 A new bombshell out of the science community: flossing doesn’t work. Fuck dentists!!! 
 
 Reports the Associated Press: 
 
 The AP looked at the most rigorous research conducted over the past decade, focusing on 25 studies that generally compared the use of a toothbrush with the combination of toothbrushes and floss. The findings? The evidence for flossing is “weak, very unreliable,” of “very low” quality, and carries “a moderate to large potential for bias.” “The majority of available studies fail to demonstrate that flossing is generally effective in plaque removal,” said one review conducted last year. Another 2015 review cites “inconsistent/weak evidence” for flossing and a “lack of efficacy.” 
 
 To this I say: no? 
 
 I floss every day, and sometimes multiple times a day because Gawker Media provides its employees with the highly sought after workplace perk that is those individual floss things. Every single time I floss (at least once a day), I notice that I have removed particles from my teeth. Sometimes I may extract partial chunks of food such as red meat. Most of the time what I find on my floss is unidentifiable gunk in varying shades of white. It’s impossible to say that flossing does not make your teeth, gums, and mouth cleaner. Any flosser will confirm this. 
 
 Also flossers can easily tell who does and does not floss. Just FYI. 

 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.’” 
 
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 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.” 
 
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 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.
– According to a new AP report, we're all in the pocket of Big Floss. Despite the American Dental Association touting the benefits of flossing since 1908 and the federal government pushing flossing since 1979, there's actually very little evidence it does anything to stop cavities or gum disease. The AP looked at 25 studies over the past 10 years and found only "weak, very unreliable" evidence in support of flossing. Even studies organized by the nearly $2 billion-a-year floss industry didn't show results. And the few studies that did confirm the benefits of flossing appeared to be majorly flawed. For example, one study cited by floss-backers looked at only 25 people after a single round of flossing. This news is, understandably, perplexing the internet. "Every single time I floss (at least once a day), I notice that I have removed particles from my teeth ... It’s impossible to say that flossing does not make your teeth, gums, and mouth cleaner," writes Jordan Sargent at Gawker. "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?" adds Hannah Keyser at Deadspin. Meanwhile, dentists aren't likely to stop shaming you for not flossing any time soon. "We know there's a possibility that it works, so we feel comfortable telling people to go ahead and do it," one dentist tells the AP.