Dr. Jeff Shnall
Beech Dental
Creating Beautiful Smiles
Call: 416.691.2886

Patient Education 2

Why you should still be flossing: Part 3

August 17, 2021

​By Dr. Jeff Shnall

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In this article I would like to share a few final thoughts with you on the controversy that arose 
when the Associated Press (AP)  wrote their August 4, 2016  titled “The medical benefits 
of floss unproven.”
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The AP article  stated  that  the US government’s publication “Dietary Guidelines for Americans” (which is issued every five years) dropped flossing as part of their daily recommendations,  due to a lack of research showing it to be effective in preventing cavities and gum disease.

     The AP article caused quite a sensation across North America  as other  media outlets picked up the story and ran with it.  An internet search on the topic shows that other influential media sources were quick to promote the notion that the benefit of daily flossing is questionable and unproven due to claims made in the AP article. 

   The AP article also quotes a few dentists who give advice on why one shouldn’t floss that run  contrary to accepted practises and guidelines  in the profession.

    What has resulted from the AP article has been a lot of confusion about the merits of flossing.  The amount of negative press that flossing has received from claims made in the  AP article warrants this additional essay to set things straight.

    The assertion made in the AP article  that flossing is ineffective in removing plaque or that it does little to prevent cavities or gum disease is puzzling to me as it must be to most dentists.  Afterall, floss is simply a tool that removes sticky bacteria or plaque that clings to our teeth in places where a toothbrush can’t  reach and especially  in between our teeth.

    Bacteria or plaque has been firmly established for decades to be the cause of gum disease and cavities.  That is indisputable.  Flossing  is a popular method for removing plaque from in between the teeth and the cleaner your teeth are, the healthier your mouth will be.

    As stated earlier, when the Associated Press reported that the  US government’s publication “Dietary Guidelines for Americans” dropped flossing as part of their daily recommendations,  the AP  reported it was due to a lack of research showing it to be effective.

But here are some additional acts that the AP didn’t mention.

◾  The 2010 edition of the Dietary Guidelines for Americans was a 112 page document.  

◾  Out of the 112 pages, there was one short paragraph  devoted to the improvement of oral health and it read as follows:

Fluoride and hygiene are keys to oral health:
“Drinking fluoridated water and/or using fluoride-containing dental products helps reduce the risk of dental caries. Most bottled water is not fluoridated. With the increase in consumption of bottled water, Americans may not be getting enough fluoride to maintain oral health.
During the time that sugars and starches are in contact with teeth, they also contribute to dental caries. A combined approach of reducing the amount of time sugars and starches are in the mouth, drinking fluoridated water, and brushing and flossing teeth, is the most effective way to reduce dental caries.”

◾  The  2015 edition of the Dietary Guidelines for Americans omitted this entire paragraph and  made no mention of how to improve oral health.  The AP  gave the impression that only the recommendation of daily flossing was dropped. 

◾  The chair of the advisory committee that wrote the 2015 US dietary Guidelines is  Dr. Barbara Millen.  Dr. Millen  was quoted in the August 3, 2016  edition of the “Fiscal Times”  regarding the omission of advice to floss and all other oral health care measures in the 2015 guidelines  as follows:

 “We didn’t look at oral health outcomes, because it was not a priority area that the committee chose to focus on.  We took a different approach than previous guidelines, focusing on the totality of the diet.”

◾  The discontinuation of the flossing, brushing and drinking of fluoridated water recommendation therefore was not due to a lack of sound science to back up the practise but instead was due to the committee’s decision to simply no longer  comment on oral health.     

This should probably not come as a surprise given the following  quote from the Introduction to the 2015 US guidelines.

“The Dietary Guidelines for Americans: What It Is, What It Is Not
The main purpose of the Dietary Guidelines is to inform the development of Federal food, nutrition, and health policies and programs. The primary audiences are policymakers, as well as nutrition and health professionals, not the general public. The Dietary Guidelines is a critical tool for professionals to help Americans make healthy choices in their daily lives to help prevent chronic disease and enjoy a healthy diet. It serves as the evidence-based foundation for nutrition education materials that are developed by the Federal Government for the public.

       Let’s get back to other contentious issues raised by The Associated Press in their article.   They quote a dentist by the name of Dr. Damian Walmsley, who they  state is a scientific advisor  to the British Dental Association, as follows:

“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.”

Let’s take a closer look at the claim:  “Careless flossing can damage gums, teeth…”

In my opinion it would be quite rare for someone to damage their gums or teeth from flossing.  I have been in practise for over 25 years and I have yet to see a patient who “damaged their teeth or gums” from flossing beyond irritating them if they were too heavy handed.  I have seen far for dental disease in  patients who don’t floss regularly than in  those who do floss. 

    Let’s look at the claim that “flossing can damage dental work.” 

 I am sure that most  dentists have  come across at least one patient who has told them “I was flossing and a piece of my filling came out with the floss.”  In this situation would it be wise for the patient to never floss again, for fear of removing or dislodging other fillings?  Absolutely not!  If a filling is  pulled out of while you floss it means that the tooth or  filling has developed a problem.    A well designed, well placed filling in a tooth that is free of decay should generally not be able to be dislodged by flossing.  And if it has been loosened or dislodged  it is a sign that either there is either decay starting around the filling, the filling has a crack or  there is  some other defect in the tooth or filling.  

       Would it have been better that this patient didn’t floss in the first place?  After all, the filling probably would have stayed in the tooth possibly months longer if the floss had not pulled it out.  I don’t know about you, but if it were me, I would prefer to know sooner rather than later that  my tooth or filling has developed a problem that requires attention.  When a cavity starts around a loose or cracked filling it can  sometimes become very deep  as bacteria can invade the tooth around the defective or cracked filling. 

When a patient has lost a piece of filling because the floss pulled it out it allows a problem to be detected sooner and the tooth fixed in a more timely manner.  So I have to absolutely disagree with Dr. Walmsley on this point.

    The same line of reasoning holds for crown and bridge work.  If floss pulls out a permanent crown or bridge then it is a sign that there is something wrong i.e. a cavity starting under the crown or  bridge.  Routine flossing will not pull out a sound crown or bridge unless you are pulling on it with all of your strength, and often that won’t even dislodge a crown or bridge.
(Note:  temporary crowns and bridges have to be flossed more delicately than permanent ones or improper flossing  can indeed pull out a temporary crown, bridge as well as temporary fillings.

    Let’s discuss Dr.  Walmsley’s comment:   “Flossing can dislodge bad bacteria that invade the bloodstream and cause dangerous infections especially in people with weak immunity, according to the medical literature.”

     Our mouths are home to billions of bacterial cells  that line every available surface including our cheeks, tongue and teeth.  The bacteria under our gumline has been shown to enter the bloodstream under many normal daily activities such as when brushing our teeth and even chewing.  The amount of bacteria entering the bloodstream is higher if you have gums that are  bleed easily to the touch  or are swollen.

When bacteria is present in the bloodstream it is called a bacteremia.

Flossing is just one of many daily activities that can cause a bacteremia.

The  microbiology  journal, Clinical Microbiology  Revue ( Jan 2009) states in an article on oral bacteremias:

Bacteremias from normal daily activities such as chewing and brushing your teeth are common and are not a threat to our health since our immune system kills or neutralizes the bacteria before it can travel and lodge  into distant organs (such as the heart) to cause infection.

So when are bacteremias something to be taken seriously?

According the the American Heart Association (AHA) bacteremias can result in serious heart infections in a small number of patients with specific medical conditions such as having  artificial heart valves or  certain congenital heart conditions. For example, bacteria entering  from the gum line can travel through the bloodstream and lodge in the artificial  heart valve causing a life threatening condition known as subacute bacterial endocarditis (SBE).

    The AHA advises that this select group of patients who are at  at risk of SBE  bacteremias associated with more invasive dental procedures such as tooth extractions, dental cleanings  or gum surgery  take an antibiotic  1 hour before the invasive dental  procedure.

The thinking behind this is that if an extraction is done, for example, any bacteria that enters the patient’s  bloodstream during the procedure will be killed by the antibiotic that is already in the patient's bloodstream  before the bacteria can lodge into an artificial heart valve.

So given all this information here are some key points about how all of this relates to flossing:
The AHA states:
  1. daily actives such as brushing, chewing and flossing do not result in bacteremias significant enough to cause worry in patients who are prone to SBE.
  2. Patients prone to SBE should  floss daily to keep the amount of bacteria accumulating in between the teeth to a minimum.

So the American Heart Association is advising the public to do exactly the opposite of what Walmsley is advising  in the Associated Press article.

So If you are a patient with a prosthetic heart valve or other condition that would make you susceptible to SBE it is extremely important that you  see a dentist and hygienist regularly to ensure your teeth and gums are in  good health.   Daily flossing and brushing or other tools recommended by your dentist should be used to keep the amount of plaque/bacteria at and under  the gumline to a minimum.  This would limit the amount of bacteria entering the bloodstream the next time you have a dental cleaning, extraction or even after daily activities such as brushing, eating and flossing.  

   Well that will do it for now regarding this topic.  I hope that I was able to shed some light on the issues raised in the Associated Press article.

    There is, contrary to claims made in the AP article, decades of research showing the benefits of flossing and the simple fact is that if you floss you will have less plaque on your teeth and in between your teeth than you will if you don’t floss,  and on average, this will translate into fewer cavities and healthier gums.    

If the articles in this series have raised any questions or if you have any feedback please do leave a comment.  I look forward to hearing from you.
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Dr. Jeff Shnall   Sep 2016
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