To floss or not to floss? U of T experts explain

(photo by G M via flickr)


You likely don’t love it. You may think everyone in the world is doing it but you. And now, thanks to a recent study suggesting that flossing may not be all that effective, you may think you can give it up for good. 

But should you throw out that dental floss?

Writer Erin Vollick of the Faculty of Dentistry put that question and more to a panel of experts at U of T:
Amir Azarpazhooh, associate professor and dental public health specialist, Faculty of Dentistry
Laura Dempster, associate professor and expert in preventive health, Faculty of Dentistry
Wafa El-Badrawy, associate professor of restorative dentistry, Faculty of Dentistry
Jim Lai, vice-dean, education at the Faculty of Dentistry and head of the graduate specialty program in periodontology

Flossing is supposed to help prevent periodontal disease and gingivitis. Can you explain what these are?

Jim Lai: Periodontal diseases are a group of inflammatory diseases. The presence of bacteria leads to a host inflammatory response. The mildest form is gingivitis where the gums become red, swollen and bleed easily. Gingivitis is reversible. A more destructive form is periodontitis where if untreated, periodontitis will lead to tooth loss. These are complex diseases with multifactorial risk factors. 

As a result, oral home care needs to be specific to the patient. Some patient will benefit from flossing while other patients, the use of interdental brush would be more effective. These types of decision requires the clinical experience of the practitioner and in addition to the understanding of the evidence available.

The study says flossing does not prevent cavities, or caries. What are these, and what causes caries? 

Wafa El-Badrawy: Caries is formed when a specific type of bacteria (streptococcus mutans), normally present in the oral environment, reacts with carbohydrates found in plaque and food debris. The reaction produces an acid that attacks the enamel surface causing demineralization with loss of calcium and phosphorous. If the situation does not change, demineralization will continue until a cavity is formed. 

How was flossing traditionally thought to help prevent this disease? 

Wafa El-Badrawy: Proximal caries (caries that forms in between the teeth) starts typically below the contact areas between the teeth. Flossing is the mechanical process that helps to clean these inaccessible areas that the toothbrush cannot reach. Flossing removes plaque formed on these in-between surfaces and, as a result, helps to prevent acid formation necessary for progress of caries. 

Based on the evidence, is dental floss still a good tool to prevent gum disease and caries?

Laura Dempster: What we do know is that no matter how well you brush your teeth, you cannot remove plaque and food debris from all tooth surfaces with a toothbrush.  You need to use floss or some other product to clean between your teeth. Figure out what works best for you!  The best idea is to consult your dentist or dental hygienist, as they can help you find the right product that works for you, and to show you how to use it properly.  

Wafa El-Badrawy: If an individual does not floss, plaque accumulation below the contact area will build up and remain attached to the tooth surface. Bacteria will then react with it to form acid that causes demineralization of enamel with subsequent formation of a carious lesion (a cavity).

This study sparked huge media interest – and also confusion - what should we conclude?

Amir Azarpazhooh: Overall there was insufficient evidence to claim or refute a benefit for flossing in reducing plaque at 1, 3 or 6 months. Furthermore, it is not possible to state whether flossing may be beneficial in reducing the risk of dental caries as no studies were found that investigated caries as an outcome.  

That said, flossing plus toothbrushing showed a statistically significant benefit in reducing gingivitis compared to toothbrushing alone at these three time points, with a moderate effect at 6 months. Overall studies are not reporting adverse effect, or for a small number, gingival trauma from improper use of floss – hence the desirable benefits of flossing in reducing gingivitis appear to be greater than the undesirable harms.

Laura Dempster: It is often difficult to directly compare research studies because they rarely investigate the same factors. As a result, findings vary across studies, which adds to the confusion of knowing which product to use. So the answer to whether floss or another product is more effective depends on many things … the answer is, the most important is the user  (their dexterity and skill, and motivation) and the conditions in their mouth (tooth alignment and oral health).  

The evidence to support flossing to control dental decay and gum disease is not undisputable.  However, not many things are. The reality is that floss can be very effective in cleaning between teeth, but it depends on whether floss is used correctly and regularly.  

If you're buying floss, what should you keep in mind?

Laura Dempster: Because there are so many different products on the market, it is difficult for consumers to know which one to use and which one is most effective. The answer is … it depends!  It depends on many factors, such as a person’s motivation, personal preference, oral health, tooth alignment, dexterity, skill using the product, and willingness to use it on a regular daily basis.  It also depends on whether you are interested in reducing cavities or gum disease.  
Amir Azarpazhooh: The brand is not as important as making it work, and using it properly. Dental offices usually give samples for free: try several samples and buy the one that you are comfortable using. 

(Visit flickr to see the original of the photo used above)

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