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To floss or not to floss?
by Nikos Mattheos - Friday, 19 August 2016, 11:46 PM

To floss of not to floss..? 
About flossing away the evidence and more...

...In the last few weeks, I've had a few patients asking me what's the purpose of dental floss and if it's all in vain..!

...some few went even further to give me that suspicious "hmmm -really?" look when I recommended interdental brushes...

...and even the most disciplined of my patients have come across the thought that so many kilometres of this tiny white ribbon have been wasted in vain...

So, is it true?Has the world come upside down?  Is flossing useless? 

Well, to strat with, don't rush to flush the floss down the toliet..!   Let's give it a calmer thought! 

 I think what we are caught up with in the case of flossing is not about a medical myth being busted, but rather yet another example of the so called "evidence based Hysteria".

Evidence Based Medicine is a concept developed to free the world of healthcare from individual opinions of all sorts of "experts" , "gurus" and allow decisions to be based on unbiased, objective,  scientific reserach data. Soon however, this noble cause was misinterpreted by some as  the demand  for the highest level of research in order to accept that a procedure is justified. The highest level of evidence is a Randomised Controlled Trial (RCT) , something that requires significant time and costs to be materialised and which in some cases is simply impossible for technical or ethical reasons. Full stop, emphasis on the "impossible".

 In the last few years however, many  "hysteric" calls have surfaced about several medical procedures, implying that unless there is a prospective or  randomised clinilical trial to support it, a procedure  is based on "weak" evidence or is unfounded. 

It is well establisehd that plaque is the cause of periodontal disease and similarly that flossing (or  better "interdental cleaning" of which flossing is one way ) can disturb biofilm and prevent disease. Clinical and in vitro studies provide a good understanding for this. However, we do not have the highest level of evidence to prove it, like a randomised trial. This  is simply not feasible. Such a trial would take many years and would need to involve many people, as periodontal disease is a very slow process. The cost of such as study would be huge!

 If you were a funding agency and you sit on one million dolloars only, where would you chose to spend?
In a study on pediatric cancer or a study about flossing?

Seriously! Furthermore, there is an ethical loophole, as such a  study would require a group of patients to be asked to not clean between their teeth for comparison purposes, something no ethical committee will allow!

The recent "mythbusting" news was not saying that flossing does not work. It simply said that the quality of studies we have to show that flossing works is not of the highest level.

Sure. So what? Is flossing yet another conspiracy of the industry? 

On  this rationale, I can actually say today that the evidence we have that HIV is a sexually transmitted virus is actually even weaker!  And this would be true, because there is no clinical experimental study actually proving that HIV is sexually transmitted and if we want to prove this at the highest level of evidence, we will need to sacrifice a couple of hundred volunteers! So before we go on and blame condoms to a conspiracy theory of the industry, think again!

The truth is that flossing is essential for many patients,
even if we cant bother to prove it at the highest level of evidence.

It is also true that we scientists have great responsibility when embarking on "mythbusting" Cochrane reviews, in order to prevent misinterpretations that actually will cause more public harm than benefit. Maybe it's time to reconsider the purpose of spending time and man/hours on systematic reviews which merely just state the obvious. 

At the end of the day, if the evidence for flossing is weak, is because none of us, Periodontists, bothered to produce it! So if you think a randomised clinical trial about flossing is what we need right now, please, go ahead and do it and show us all the truth. 

The rest, in my humble opinion is just too much trouble for nothing. 


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