Do I Need to Floss? What Does the Research Show?

What is Flossing?

Flossing is one method of interproximal cleansing -- a fancy way of saying cleaning between your teeth. It is one of the oldest methods for doing so dating back to the 1800’s when it first became commercially available^1,2.

But Does it Work?

Well, here’s the issue: flossing from a research perspective has never been sufficiently studied. Yes, the thing dentists and dental hygienists have guilted patients on for over a century was never properly researched. If fact, so poor was the existing research in determining the benefits of flossing that in 2016 the US departments of Health and Human Services and Agriculture quietly dropped their previous recommendations for doing so ³ . Their reasoning was justifiable -- the dental associations never demonstrated, with rigorous proof, that flossing actually does prevent cavities or gum disease.

Now before any of my dental friends send me messages denouncing me as a heretic, let me be clear: I’m not saying I don’t recommend it, nor that it isn’t beneficial, just that it’s never actually rigorously been proven to be so.

There are numerous factors that can diminish the validity of a research study. Those include:

• Corporately sponsored bias,
• The timing under which the study was conducted,
• The way the results were assessed or even
• The specific question it sought to answer⁴.

Cochrane Speaks Out

There are few studies that are not sponsored by some corporation. An exception to this sad state in science is Cochrane.

Cochrane is a scientific research society that prides itself in keeping corporate bias from affecting its conclusions.

In 2019, Cochrane published a meta-analysis of the studies on flossing (meaning it reviewed all existing literature) to determine if flossing was in fact effective in reducing cavities and gum disease more that brushing alone¹.

Their conclusions were devastating to flossing advocates – they determined that floss or interdental brushes (in addition to toothbrushing) may reduce gingivitis or plaque more than toothbrushing alone. The evidence for tooth cleaning sticks and (water flossers) they found to be limited and inconsistent. And overall, the evidence showed low to very low-certainty, and the effect sizes observed were not clinically important.

Essentially, they said that none of the studies they reviewed were sufficiently long enough to measure gum disease or cavities, and they didn't include patients with the right level of those diseases¹.

Why do Dental Professionals Still Tell You to Floss?

Even in the face of that evidence, dental professionals will still ask patients to floss, for the simple reason that we know reducing biofilm is essential to minimizing risks for cavities and gum disease^{2, 5-7}.

Cochrane did not state biofilm reduction wasn’t necessary, just that there were no rigorous studies to prove flossing, interproximal brushes or water-flossers were better than a toothbrush alone¹. Occasionally, I have patients with very good brushing habits, and low risk factors for oral disease -- if they aren’t flossing already, I won’t ask them too.

Recommendations for home care should really boil down to a customized care plan from your dental provider, based on your risks, your level of motivation, your dexterity and the condition or positioning of your teeth⁸. If your dental provider takes the time to determine flossing is an ideal method for you -- you’d do yourself a favor to at least try.

How to Floss Correctly:

If you are going to be flossing, you should learn to do it correctly. Following these steps will make it easier for you:

• Take about a shoulder’s width amount and wrap it around your middle fingers, leaving 6-8 inches between them. (This allows you to use your index fingers -- or index finger and thumb -- to guide you. Holding the floss this way gives you the ability to reach to the back of your mouth and also, quickly adjust to a fresh area along the floss if it should fray or have too much debris on it.)
• Gently work the floss between your teeth until you’re just under the contact point (the point where the teeth are tightest),
• Adapt the floss to the tooth using a c-, or reversed c-shape; then use a back-and-forth wiping motion, going just under your gumline.
• When you’re finished with one side, come back up and wipe the tooth adjacent. For the back teeth, this c-shape motion becomes a pull forward and wipe, push backward and wipe. The key point to remember is that you are wiping the sides of your teeth.

What You Should NOT Do:

• Don’t just pop the floss in and out – that might dislodge a stubborn piece of food, but it won’t clean the sides of your teeth.
• Don’t aggressively drop the floss straight down over your gum tissue -- this can lead to permanent rips or tears that require expensive grafting procedures to fix.

What is the Best Type of Floss?

As a general rule of thumb: the thicker floss is the better floss. Why? Because a thicker floss inherently has more substance to reduce plaque and biofilm. For patients with significant gum recession, some professionals will even recommend using non-wool, un-dyed yarns to wipe larger spaces between teeth.

Floss has three basic categories:

• Thin, gliding tapes,
• Waxed flosses which are the most common, and
• Expanding, woven flosses.

Woven Floss

Unfortunately, there are very few woven flosses on the market and even fewer available in stores. Why? Suppliers are in the business of making money⁹. They provide what people are more likely to buy, not necessarily what is best. If their marketing research shows the public is more interested in a fast and easy to use floss – that’s what they’ll sell.

Many flosses advertise their ease and speed of use, not how well they clean your teeth. These companies are for-profit businesses -- their interests are in selling product – not necessarily your oral health.

Among the woven flosses, there are two advantages for using one of the charcoal-infused ones: first they create a great visual contrast of the plaque against the floss making it really obvious how much its actually doing and secondly, because it reduces biofilm better, it’s also able to reduce some of the yellow staining you’ll see accumulate between professional cleanings.

When You Should NOT Floss at All:

Studies published over the past ten years are suggesting that regular flossing around implants can lead to gum infections^{10, 11}. Researchers found that micro particles of floss and plastic instruments can adhere to the interface between the crown and the implant body causing irritation to the gums^{10, 11}.

Caring for an implant should involve twice daily water flossing, and careful brushing, rather than working floss around it. This is an instance where you should NOT use traditional floss.

Recapping

• Reducing the biofilm between your teeth is necessary^{2, 5-7}. I don’t care how you do it, as long as its effective for you.
• If you are using a floss, get the thickest appropriate for your teeth and use a wiping motion.
• Be thorough but gentle when flossing.
• If you have implants, braces, or bridges – use a water-flosser rather than traditional floss!

References:

1. Sambunjak D, Nickerson JW, Poklepovic Pericic T, et al. Flossing for the management of periodontal diseases and dental caries in adults. Cochrane Database Sys Rev. 2019(4).
2. Hujoel PP, Cunha-Cruz J, Banting DW, Loesche WJ. Dental flossing and interproximal caries: a systematic review. J Dent Res. 2006;85(Generic):298,304.
3. Saint Louis C. Feeling guilty about not flossing? Maybe there’s no need. New York Times; 2016.
4. Yin RK. Validity and generalization in future case study evaluations. Evaluation 2013;19(3):321-32.
5. Holt R, Roberts G, Scully C. ABC of oral health: dental damage, sequelae, and prevention. Brit Med J. 2000;320(7251):1717-18.
6. Marsh PD. Dental plaque as a biofilm and a microbial community - implications for health and disease. BMC Oral Health. 2006;6 Suppl 1(S1):S14-S14.
7. Axelsson P, Nyström B, Lindhe J, et al. The long-term effect of a plaque control program on tooth mortality, caries and periodontal disease in adults. Results after 30 years of maintenance. J Clin Periodontol 2004;31(9):749,55.
8. Berchier CE, Slot DE, Haps S, Van der Weijden GA. The efficacy of dental floss in addition to a toothbrush on plaque and parameters of gingival inflammation: a systematic review. Int J Dent Hyg. 2008;6(4):265-79.
9. Friedman M. Prophet sharing: Hoover fellow Milton Friedman explains in this famous article the "one and only one social responsibility of business.". Hoover Dig. 2020(1):16.
10. Van Velzen FJJ, Lang NP, Schulten EAJM, Ten Bruggenkate CM. Dental floss as a possible risk for the development of peri-implant disease: an observational study of 10 cases. Clin Oral Impl Res. 2016;27(5):618-21.
11. Montevecchi M, De Blasi V, Checchi L. Is implant flossing a risk-free procedure? A case report with a 6-year follow-up. Int J Oral & Max Imp. 2016;31(3).