In Response To The Associated Press News:

Medical Benefits of Dental Floss Unproven

Yes, flossing works.
Yes, flossing works.

A few days ago, the Los Angeles Time picked up an article from the Associated Press entitled: “Haven’t flossed lately? Don’t feel too bad: Evidence for the benefits of flossing is ‘weak, very unreliable'” As a dentist, periodontist, and health professional I felt compelled to write a response and share it here, on our blog, as well as via e-mail with patients and colleagues.

There is little “high quality” evidence for most of what’s done in medicine or dentistry.  Indeed, when “evidence based decision making” became a big deal starting in the late 1990s, many people twisted it to mean that a “lack of evidence” is somehow proof that the procedure in question doesn’t work.  Indeed, one sees this sort of misleading rhetoric all the time in other areas, especially in politics, sex and religion”.  And to be sure… there is plenty of politics in healthcare, sex and religion. The media thrives on misconstruing the facts and creating rhetoric.

That said, Tim Iafolla’s comments (from NIH) in the LA Times article are both troublesome and perplexing.  My guess is that he was quoted only in part — because even when there is very little evidence from what are considered to be weak studies, many procedures are recommended based on cost versus risk and in consideration of perceived benefits. It is fascinating how few “experts” seem to intuitively understand that every decision we make in life, from how we perform oral hygiene to changing lanes on the highway are most often considered in cost/benefit terms. Flossing studies? Who is going to pay for a study to follow 500 patients for 10 years? We learned in the 1960’s that a buildup of plaque bacteria, now called biofilms, causes bleeding gums and gum disease. We proved that removing said plaque allows the gums to heal. We have very strong medical evidence that inflammation anywhere in the body is bad and affects the entire system negatively. While some patients that are resistant to gum disease may not get much benefit from flossing, it helps many people quite a bit. And, truth be told, floss is not a goal it is a tool and other tools can be used besides floss to remove plaque. The idea is to remove the bacteria that cause infalmmation to a low level to prevent disease. This needs to be done between the teeth and floss is one tool that accomplishes that goal.

So yes, it is true, we don’t have high-quality evidence for flossing but that doesn’t mean it isn’t useful (just like we don’t have high-quality evidence that jumping off the US Steel Building is likely to be fatal).  And in light of the low costs of flossing and its potential benefits, is it not better to over-recommend flossing to reduce inflammation and disease than to under-recommend it?

But in a larger sense, this sort of near sighted thinking regarding evidence can easily spin out of control.  An LA Times author seeks to write a compelling article questioning and criticizing a long accepted practice. Kudos to him or her, that’s how one gets ahead in journalism-sometimes truth be damned.  But I can’t tell you how many times I hear otherwise smart folks condemn certain approaches in medicine, dentistry, life, etc. because supportive evidence is weak or not there at all.  Often this is done with a bit of ignorant intellectual arrogance that shouts: “I’m using evidence-based criteria here!”  Sorry Dr. knows it all… this is a fallacy that’s based on the all too frequent failure to only understand evidence-based decision making on the most superficial level.  Yet this foolishness seems increasingly widespread, all pivoting off the same and increasingly popular shallow thinking about what evidence (and lack of evidence) means and doesn’t mean.

So this is the most important thing to remember: A lack of high quality evidence is not proof that there is no benefitThe lack of evidence does not prove that something does not work or is not effective. Thus, the lack of evidence only means that there is a lack of evidence.  And, because most of the time high-quality evidence has never been sought, the journalist that seeks to sensationalize and write a high profile story that garners national attention will get just that-a lot of attention even if the story is biased and untrue.


May The Floss Be With You

Dr. Mark Silberg


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