Dr. Shnall's Dental Blog
Associated Press Advice to Stop Flossing is Misguided:
By Dr. Jeff Shnall Sept 2016
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.”
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:
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.
Dr. Jeff Shnall Sep 2016
Associated Press Advice to Stop Flossing is Misguided: Part 2
This is the second in a series of articles where I respond to the Associated Press news story
entitled “Medical Benefits of Floss Unproven” I will turn my attention to what the AP article had
to say about flossing and cavity prevention. I will explain why the AP article was inaccurate and
misleading and why if you want to spend less time in the dentist chair you should definitely
make flossing a part of your daily routine.
As a practising dentist for over 25 years I was puzzled by the claims in the AP article, as i am sure
were most in the dental profession , for it is fairly evident for that flossing plays an important
role in cavity prevention.
The AP stated in their article:
“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."
(Note: the AP actually looked at five research papers that in turn pooled the results of 25 smaller studies.)
At the bottom of the AP article they listed five large studies they used to base their flossing
article on. Only one of these studies looked at whether flossing prevents cavities:
The study is titled: “Dental flossing and interproximal caries: A systematic review” (Hujoel,P.P.
et al, 2006).
In lay terms the study is trying to determine whether flossing has any effect on preventing
cavities from forming in between our teeth.
The authors, Hujoel et al did not conduct their own research to answer this question. Instead
they initially looked through 130 studies done by other researchers related to flossing and cavity
prevention . They narrowed their focus down to six studies they felt were the most suitable to
determine whether flossing reduces cavities.
Here is a summary of what the six studies found. I will list the full names of these six studies at
the end of this report.
Note: after reading the summary of these six studies you may be left wondering how the
Associated Press can claim there is no research to support daily flossing reduces cavities.
Study 1 Wright et al (1979)
Study 2 Wright et al (1980)
Wright et al used 5 and 6 year olds in their research.
In the two studies they ran, children had all the teeth on one side of their mouths
professionally flossed once a day at school, five days a week, for ten months (excluding
weekends and summer holidays).
The result: there were 40% fewer cavities on the side of the mouth that was flossed.
Comment: These two studies clearly show there was a benefit of daily flossing in these children
and negates the premise of the AP article
Study 3 Gisselsson et al (1988)
This study put 10 and 11 year olds into two groups.
In one group, children were asked to floss every night at home. Their flossing was not
supervised by the researchers. The other group of children did not floss.
The study lasted two years. As well, the experimenter put the children who had the fewest
cavities and fillings in the “flossing” group at the start of the experiment.
The results need to be looked at carefully.
There was no difference in cavity rate in the flossing versus non-flossing group.
However after the study was completed they found that most of the children who were put in
the flossing group were not flossing every day at home.
Out of 20 children in the flossing group:
Comment: the kids who were in the flossing group had the same number of cavities as children
in the non-flossing group after two years, however since children in the flossing group were not
flossing daily this study does not properly address the question whether daily flossing reduces
cavities. For this reason one may wonder why this study was included in the research paper
written by Hujoel et al.
Study 4 Gisselsson et al (1994)
Children 4 years of age took part in this study. Children in group 1 (experimental group) had
their teeth flossed once every 3 months with the floss dipped in a chlorhexidine gel.
Children in another group (control group 1) had their teeth flossed with a gel that did not contain
any medicinal ingredient.
Children in a third group (control group 2) did not have their teeth flossed at all.
The study ran for three years.
After three years the three groups were compared.
Children in the group that had their teeth flossed with the chlorhexidine gel had slightly fewer
cavities than children in the two other groups.
This study shows there is a small benefit to using a chlorhexidine gel delivered by floss four
times a year in children but it does not tell us anything about whether daily flossing reduces
cavities, as the children in the flossing group only had their teeth flossed 4 times a year in this
study. Again, completely irrelevant to the question of whether daily flossing is of value.
Study 5 Granath et al, 1979.
This study was conducted on 12 and 13 year old children.
The researchers were interested in finding out whether simply moving a piece of floss once up
and once down in between the teeth would have any effect on the rate of cavities In children.
(Note: It important to know that this is not the correct way to floss.
The purpose of flossing is to remove bacteria (plaque) that clings to the surfaces of our teeth
where the toothbrush doesn't reach.
Bringing a piece of floss up and down once in between the teeth might remove lodged food but
would not do much at all to disturb or loosen all the plaque that sticks to the tooth surface, as
plaque is made up of bacteria that produces chemicals that glue it quite effectively to the tooth.
The proper way of flossing is to bring the floss in between the teeth and rub the floss several
times against the side of one tooth and then the other to loosen the sticky plaque off the side
of the tooth.)
Each child in the study flossed their teeth only on one side of their mouth, at school under
supervision every day for two years. They did not floss the other side of the mouth.
Granath et al found no significant difference between the amount of decay or cavities on the
side that children used floss compared to the side they did not use floss.
The study found that the simple up and down once method of flossing is of no benefit in
reducing cavities. This does not mean we should give up on flossing; rather, it reinforces the fact
that flossing has to be done properly to achieve any cavity reducing effect.
Study 6 Gisselsson et al, 1983.
This study was focused on a group of 10 and 11 year olds who were found to be the most prone
to cavities and gum inflammation out of a pool of 627 children.
87 of the children most prone to cavities and gum inflammation had their teeth professionally
cleaned every two to four weeks based on individual need for the next two years and we're also
given diet counselling and reminders on how to brush properly. Approximately half of the
children (experimental group) were also shown how to floss and advised to floss daily at home
while other half were not (control group).
Gisselsson states that at the end of the two year program of regular dental cleanings (every 2 to
4 weeks), children in the daily flossing group (which was at home, unsupervised) had
significantly fewer cavities than the group of children in the “no flossing group.”
Then they waited another two years and again checked cavity rates in the two groups.
This time they found that children in the “flossing” group had more cavities than kids in the
“non-flossing” group, however when they further into the matter they found that very few of
kids in the “flossing” group reported to actually flossing at home more than once or twice a
It should be noted that within the “flossing group” children who said they flossed at least three
times a week did not develop any cavities after the second two year follow-up period.
This study shows children who flossed daily or several times a week indeed had significantly
fewer cavities than children who did not floss.
I looked at the six studies that Hujoel et al used in their research paper.
I would say that studies 1, 2 and 6 showed that children who flossed daily developed fewer
Study 3 was unsupervised home flossing and unfortunately not enough children who were
supposed to be flossing daily actually did so.
In study 4 kids in the “flossing group” had their teeth flossed a total of 4 times a year so any
results of the study do not shed light on the question regarding whether daily flossing prevents
Study 5 showed that if you use poor flossing technique you are not going to get a reduction in
So, in light of the studies discussed in this paper what is the take home message about flossing
and does it agree with the Associated Press article that claims flossing to be ineffective and
I would say that based on the six research studies that Hujoel et al selected, we can conclude
could conclude that the Associated Press did not dig very deep when writing their article that
disparaged flossing and clearly could not have read the six source studies used by Hujoel et al in
their research paper.
These four recommendations I listed above can be expected to reduce the number of cavities
children get, whereas not flossing daily or at all will assuredly increase the risk of developing
In this article discussed we only discussed flossing in children. The AP did not cite any research
that answered the question whether daily flossing prevents cavities in adults. However, It is
obvious to anyone who practises dentistry that daily flossing in adults is an important part of a
cavity reduction program and compliments daily brushing, as our toothbrush cannot effectively
remove plaque and food between our teeth.
In my next article(s) on this topic I will address more misinformation contained in the AP article
and further the case for daily flossing.
Dr. Jeff Shnall Aug 2016 email: Dr.Shnall@gmail.com
BeechDental.com 350 Beech Ave Lower Suite, Toronto, Ontario M4E 3T8 tel 416-691-2886
Articles Used in the Research Paper by Hujoel et al:
The abstracts to these studies are available online.
Studies 1 and 2: Wright,GZ, Banting DW, Feasby WH (1979). The Dorchester dental flossing final report. Clin Prev Dent 1: 23-26
Study 3: Gisselsson H, Birkhed D, Bjorn AL (1988) Effect of professional flossing with
chlorhexidine gel on approximal caries in 12 to 15-year-old schoolchildren. Caries res 22: 187-192
Study 4: Gisselsson H, Birkhed D, Bjorn AL (1994) Effect of a 3 year professional flossing program with chlorhexidine gel on approximal caries and cost of treatment in preschool children. Caries res 28: 394-399
Study 5: Granath LE, Martinsson T,Matsson L et al (1979) Intraindividual effect of daily supervised flossing on caries in school children. Community Dent Oral Epidemiol 7:147-150
Study 6: Gisselsson H, Bjorn AL, Birkhed D (1983) Immediate and prolonged effect of individual preventive measures in caries and gingivitis susceptible children. Swed Dent J 7: 13-21
Associated Press Advice to Stop Flossing is Misguided: Part One
By Dr. Jeff Shnall
On Aug 2 of this year the Associated Press (AP) put out an article entitled ”The medical benefits of floss unproven”.
The article sites the fact that the US Department of Dietary Guidelines for Americans has dropped its recommendation for people to floss because “the effectiveness of flossing has never been researched.”
The AP article then goes on to say:
“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."
So essentially the AP is saying that they have looked at the most reliable dental research research that has been done that put people into two groups: one group that was told to brush only and the other group was told to brush and floss daily. After a number of weeks or months the two groups were examined and compared to see if the gums and teeth in one group were healthier than the other. If flossing was beneficial we should expect the group that flossed to have healthier gums.
The AP article implies that after they scoured all the best research done in the field of dentistry, the consensus is that flossing is a complete waste of time and that it does nothing to promote good dental health. The AP article also makes claims that it is in the interest of manufacturers of dental floss to promote the myth that flossing plays a role in maintaining dental health as floss sales are estimated to be worth a billion dollars a year in the US alone.
A lot of media outlets including newspapers and the evening news picked up the AP article and ran with it. I can understand why. Flossing is to many, one of life’s little drudgeries. It isn’t easy for some people to maneuver the floss; some people have trouble getting the floss in between tight contacts in between their back teeth; as well it takes time out of your day and can be tedious. I try to read or watch tv while I floss to beat the sheer boredom factor.
As a dentist I routinely ask my patients if they floss and the standard answers are: “not as often as I should”, “when i remember”, “after i eat corn on the cob” or “when i get food stuck between my teeth”. I do have few patients who are brave enough to give me a flat out “no’, and yes, I do also have some daily flossers in my practise.
After hearing the AP report I am sure some people were in a hurry to fling their their floss into the nearest garbage can or at least keep it around for some emergency repairs like sewing loose buttons or as an emergency shoelace substitute as it is strong and durable.
However recommending that everyone stop flossing due to alleged lack of scientific evidence not a trivial matter. As a practising dentist I think the AP article does not make a sound argument against daily flossing. I would like to point out some shortcomings of the AP article and also explain why I think flossing is a worthwhile endeavor based on what I have observed while caring for teeth and gums for at least half of my waking hours for the past 25 plus years.
As mentioned the AP states in their article that:
“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.”
I would like to comment on this quote. In fact, only some of the studies that the AP based their article on directly compared whether people who used a toothbrush and floss had healthier gums than those who only used a toothbrush. And the results of some of those studies do not support the AP notion that flossing is ineffective.
Moreover I will argue that almost half of the brushing versus flossing studies the AP looked at were conducted on young, healthy experimental subjects only, thus limiting any conclusions they made on the utility of flossing applicable to young, healthy people only (at most) and if at all.
As well, the bulk of the studies the AP looked at did not even consider whether flossing helps prevent cavities, which is a definite benefit of flossing.
So let us take a closer look at the question: does daily flossing make your gums healthier and can it prevent gum disease? ( I will discuss the AP article as it relates to cavity prevention in a future article in this series).
In my opinion, and I believe in the opinion of the majority of dentists and dental hygienists , flossing is a very worthwhile daily practise. It promotes healthier gums and most patients will benefit from daily flossing.
First, let’s discuss a little about the nature of gum disease and how many people are affected by it.
For the purpose of this discussion we can group people into four different categories based on the health of their gums:
Category 1: Healthy gums. No sign of gum swelling or bleeding. Gums pink in colour.
Category 2: Mild gingivitis or mild gum inflammation: one or more areas of red or puffy gums that might bleed when touched
Category 3: gum disease in one or more areas of the mouth i.e. may have bleeding or swelling at the gum line and early loss of bone that supports the teeth.
Category 4: generalized moderate or severe gum disease affecting many areas or the mouth; may include swelling and or bleeding a the gum line and moderate or severe loss of bone that supports the teeth
How prevalent is gum disease?
Health Canada reports that over 50 % of the adult population has some form of gum disease.
The Centers for Disease Control and Prevention (CDC) in the US reports the same figure.
So gum disease is a very common condition affecting adults but clearly not everyone has gum disease. Why is that?
This can be explained in part due to the nature of gum disease, that being it is an inflammatory disease.
GUM DISEASE IS AN INFLAMMATORY DISEASE
There are many reasons why some people have healthier gums than others.
Some people have gums that are more prone to inflammation than others and people who are more prone to inflammation in their gums are going to have a greater risk of gum disease.
What is Inflammation?
Inflammation is our body’s normal reaction to injury or attack by foreign invaders (such as bacteria) and is part of our body’s natural defense system.
When we are injured, our body’s defense system kicks in to the minimize the damage. If we suffer an injury, for example if we fall down and scrape our knee the following sequence of events occurs at the site of the injury:
Skin scraped ----> blood vessels in skin react by leaking fluid into the injured area (swelling and redness)
----> leaky blood vessels allow larger white blood cells into the injured area to clean up or neutralize any bacteria in the wound
This is a healthy defense mechanism that allows us to survive the bumps and scrapes that befall us through a lifetime. The response to a wound described above is called an inflammatory response.
So how does this relate to gum disease?
Our mouths are host/home to millions of bacteria that live on our teeth and along and under our gumline. We all have this bacteria.
The question of who will go on to develop gum irritation or gum disease is related in part to how your body responds to the bacteria and this response can differ from person to person.
I can see two patients at my office with the same amount of plaque or bacteria on their teeth. However in each of these two patients their gums may look and respond differently: One patient might have slight swelling, redness and bleeding in their gums while the other patient will have normal, pink and healthy looking gums that don’t bleed and are not swollen.
So why the difference between these two patients? Same bacteria and same amount of bacteria yet a different gum response?
This can be explained by the difference in the strength of each person’s inflammatory response or put another way, how prone they are to inflammation.
Inflammation is our body’s protective mechanism, however if we respond to very minor threats with an overblown inflammatory response we are going to get more swelling, more bleeding and the initiation of gum disease.
So who is the type of patient who will be more likely to have a stronger inflammatory response in their gums making them more prone to gum disease?
Medical and dental research has already provided this answer:
People who have a stronger inflammatory response to plaque or bacteria on their teeth and around their gum line also are more likely to have other illnesses linked to inflammation in other parts of their body, for example high blood pressure, diabetes and forms of heart disease such as clogged coronary arteries.
The consensus in the medical and dental community is that gum disease, heart disease and diabetes all have an underlying cause, namely inflammation.
So how does all of this relate to the original article in the Associated Press? Recall its opening lines:
“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.”
In this assertion they go on to say that they looked at 25 of the most rigorous articles that examined whether flossing was any more effective in keeping gums healthy than brushing alone.
The problem is that about half of these “rigorous” studies only looked at whether flossing would benefit healthy people. People with systemic diseases such as diabetes or heart disease were intentionally left out of the studies the AP looked at. Let’s have a closer look at this.
The AP listed the research sources that they used to write their article.
They are listed here:
Let's look at one of these studies in a bit more detail It is called “The Cochrane Database Systematic Review. 2011 Dec 7;(12). Flossing for the management of periodontal diseases and dental caries in adults. (Third link in the above list)
The authors of this study ( Sambunjak, Dario et al) did not conduct their own research on the question of whether flossing helps people. Instead they in turn looked at 11 other studies that were done by others and tried to extract data from these studies to answer the flossing question.
Sambunjak, Dario et al state that they only used data from studies that had healthy experimental subjects.
So if someone did a study on whether flossing works that included people with diabetes, heart disease or high blood pressure Sambunjak, Dario et al would not even look at results or the data in that study.
So what did the eleven studies that Sambunjak, Dario et al) looked at find?
Well, first that people who were in the brush only group for a number of weeks or months did not have any more gum inflammation than people who brushing and flossing group. (A closer look at each the eleven studies does not exactly show this but more on this in a future article).
This is not a big surprise because they were already looking at a pool of patients who were healthy, who did not have any inflammatory related diseases such as diabetes or heart trouble, and who would be expected for this reason to do relatively well even without flossing; the people in these eleven studies likely had low inflammatory responses to plaque on their teeth and under their gum line.
The people in these studies were very likely the people I referred to early in this article as category 1 patients: ( Category 1: Healthy gums. No sign of gum swelling or bleeding. Gums pink in colour.)
If Sambunjak, Dario et al, in their 2011 study, included research studies conducted on diabetics or people with heart disease or high blood pressure they undoubtedly would have found that people in the floss and brush group would have less gum inflammation than people in the brush only group, because they would have been looking at a population that are more sensitive and reactive to dental plaque and more prone to gum inflammation when plaque levels are not kept under check by flossing. This is something observed in dental offices all over the world.
It has already been widely researched and known that if you get diabetics, for example, to keep their teeth cleaner (brushing, flossing) their gums will get healthier and their blood sugar levels will also improve.
Given that over 50% adults in Canada and the US have gum disease, 9% have diabetes (25 % of senior citizens in the US), over 20% have high blood pressure, and the majority of adults in North america have one or more risk factors for heart disease or stroke the Associated Press should actually be telling people: although young and healthy people (no systemic disease) might be able to get away without flossing at least in terms of not having an impact on the health of their gums in the short term (cavities are a different story), anyone with a risk factor for diabetes, high blood pressure or heart disease should be flossing daily as these people are prone to inflammatory diseases such as gum disease:
A second study cited by the AP to prove flossing is not worth your time is entitled:
Primary prevention of periodontitis: managing gingivitisIain L. C. Chapple, Fridus Van der Weijden et al (fifth link in the article list above).
The authors of this paper did not do direct research studying the health effect of flossing; they too, like the authors of the previous study discussed above looked at healthy subjects only, so any conclusions the authors drew from their research as well could only be applied to healthy people.
Well, I tried to bring a little clarity to what is actually a fairly complex question: whether flossing is effective in reducing plaque and promoting healthy gums. In my next article in this series i will comment on some other aspects of the AP article that in my opinion are not supported by facts.
Until then I do urge you to keep flossing daily or to start flossing daily.
I welcome any comments you may have on this topic.
Dr. Jeff Shnall
Toronto, Canada BeechDental.com