Floss/Interdental Cleaners

Key Points

  • Interdental cleaning helps remove debris and interproximal dental plaque, the plaque that collects between two teeth; dental floss and other interdental cleaners help clean these hard-to-reach tooth surfaces and reduce the likelihood of gum disease and tooth decay.
  • Use of an interdental cleaner (like floss) is an essential part of taking care of your teeth and gums; the U.S. Department of Health and Human Services reaffirmed flossing as "an important oral hygiene practice" in an August 2016 communication to the ADA.
  • A company earns the ADA Seal of Acceptance by producing scientific evidence that demonstrates the safety and efficacy of its product, which the ADA Council on Scientific Affairs carefully evaluates according to objective requirements.

Dental floss (or dental tape) and other interdental cleaners (e.g., small brushes, special wooden or plastic picks, sticks or water flossers) removes food trapped between the teeth and removes the film of bacteria that forms there before it has a chance to harden into plaque.1 Toothbrush bristles alone cannot clean effectively between these tight spaces.2

Plaque that is not removed can harden into tartar, a hard mineral deposit that forms on teeth and can only be removed through professional cleaning by a dental professional.3 When this happens, brushing and cleaning between teeth become more difficult, and gum tissue can become swollen or may bleed. This condition is called gingivitis, the early stage of gum disease. Interproximal cleaning techniques (e.g., manual or powered interdental cleaners, water flossers, interdental brushes), appear to add benefits in plaque reduction when used in association with conventional manual brushes.3 The choice between technique type should be made in relation to the characteristics of the patient; for example, dental floss could be indicated in individuals with closed interdental spaces, and interproximal brushes in patients with periodontitis or in those with more open interproximal spaces.3

Interdental cleaning helps remove debris and interproximal dental plaque, the plaque that collects between two teeth.3 Dental floss and other interdental cleaners help clean these hard-to-reach tooth surfaces and reduce the likelihood of gum disease and tooth decay.1 A news release from the ADA4 reaffirmed the use of an interdental cleaner (like floss) as an essential part of taking care of teeth and gums. The U.S. Department of Health and Human Services also reaffirmed flossing as "an important oral hygiene practice" in an August 2016 communication to ADA News.5


Floss was once made from silk fibers twisted to form a long strand. Today, floss is usually made from nylon filaments or plastic monofilaments.1 The U.S. Food and Drug Administration classifies dental floss6 as a Class I device, which means it is deemed to be low risk and subject to the least regulatory controls.  Floss may be treated with flavoring agents, such as mint, to make flossing more pleasant.  There is no difference in the effectiveness of waxed or unwaxed floss,7 although rare cases of contact hypersensitivity to waxed or coated floss have been reported8. It’s generally not what type of floss is used, but how and when it’s used. Floss-related products include floss holders, floss threaders, or floss picks.

Other Interdental Cleaners

While floss is a flexible strand, other interdental cleaners specifically made for this purpose include dental/floss picks, pre-threaded flossers, tiny brushes that reach between the teeth, powered air or water flossers, or wooden plaque removers.

Interdental brushes are small-headed toothbrushes that are available in a range of different sizes to match the space between teeth.9 They can be cone shaped or cylindrical. Brushes for use for cleaning around implants have coated wire to avoid scratching the implants or causing a shock.9


A 2019 Cochrane review10 on home-use of interdental cleaning devices in addition to toothbrushing for preventing or controlling periodontal disease or dental caries found no randomized, controlled trials assessing effect on interproximal caries and very few studies evaluating periodontitis. The authors found that use of floss or interdental brushes in addition to toothbrushing may reduce gingivitis or plaque, or both, more than toothbrushing alone and that interdental brushes may be more effective than floss.10 Available evidence for tooth-cleaning sticks and oral irrigators was reported to be limited and inconsistent. Outcomes were mostly measured in the short term (i.e., 1 to 3 months) and participants in most studies had a low level of baseline gingival inflammation. Overall, the evidence was graded as low to very low-certainty, and the effect sizes observed may not be clinically important. The authors recommended that future trials report participant periodontal status according to the new periodontal diseases classification, and last long enough to measure outcomes for interproximal caries and periodontitis.10

A 2011 Cochrane systematic review evaluating the evidence for the impact of flossing on managing gingivitis11 found that by the standards of the GRADE Working Group, the evidence on this question was of very low quality, due to uncertainty about the estimate because of the small number of studies, sample sizes, and some concerns regarding interpretation of the results. With these caveats and limitations in mind, the summary of results of these short-term (i.e., up to 6 months of follow-up) investigations were that when flossing was added to toothbrushing, there was a statistically significant, albeit clinically small, reduction in the measures of gingivitis.11 An earlier meta-analysis by Berchier et al.12 explored the impact of adding flossing to brushing on indices of plaque and gingival health and failed to find statistically significant improvement. They nonetheless concluded that a first consideration ought to be whether high-quality flossing is an achievable goal.

A meta-analysis of studies examining the impact of flossing on interproximal caries13 found that regular (5 days per week) professional flossing resulted in a statistically significant reduction in interproximal caries, a result that was not seen with intermittent (every 3 months) professional flossing nor self-flossing.

Frequently Asked Questions

When’s the best time to floss?

The ADA recommends brushing twice a day and cleaning between teeth with floss (or another interdental cleaner) once a day. Some people prefer to floss in the evening before bedtime so that the mouth is clean while sleeping. Others prefer to floss after their midday meal. Still others chose to floss first thing as a part of their morning ritual. The bottom line is that best time to floss is the time that fits well with the individual’s schedule.

Should I brush or floss first?

Either way is acceptable as long as you do a thorough job. Some people like to floss before brushing to better ensure that any material between teeth is swept out of the mouth. Others prefer to first clean their mouth by brushing before working with floss between their teeth. However, those who brush their teeth and skip flossing because they think their mouth feels clean or are short on time or tired and postpone flossing for some later time are likely missing out because flossing may never happen.

Can I rinse and reuse floss?

The ADA does not recommend using a floss strand more than once. Used floss might fray, lose its effectiveness, or may deposit bacteria in the mouth. Discard after use.

ADA Seal of Acceptance: Floss and Other Interdental Cleaners

Look for the ADA Seal—your assurance that the product has been objectively evaluated for safety and efficacy by an independent body of scientific experts, the ADA Council on Scientific Affairs.  A company earns the ADA Seal for floss or other interdental cleaners by producing scientific evidence demonstrating the safety and efficacy of its product in reducing plaque and gingivitis, which is evaluated according to objective requirements for manual or powered interdental cleaners.

To qualify for the Seal of Acceptance, the company must provide evidence that:

  • Using the floss or interdental cleaner with toothbrushing is more effective than brushing alone at reducing plaque and gingivitis.
  • The product components are safe for use in the mouth.
  • Unsupervised use of the product by the average patient will not harm hard or soft oral tissues or restorations.
  • Clinical trials are not necessary for manual products similar in design and composition to dental floss or from those interdental cleaners previously Accepted by the Council.
  1. Warren PR, Chater BV. An overview of established interdental cleaning methods. J Clin Dent 1996;7(3 Spec No):65-9.
  2. Graves RC, Disney JA, Stamm JW. Comparative effectiveness of flossing and brushing in reducing interproximal bleeding. J Periodontol 1989;60(5):243-7.
  3. Sicilia A, Arregui I, Gallego M, Cabezas B, Cuesta S. Home oral hygiene revisited. Options and evidence. Oral Health Prev Dent 2003;1 Suppl 1:407-22; discussion 23-5.
  4. American Dental Association. News Release: Federal Government, ADA Emphasize Importance of Flossing and Interdental Cleaners. Chicago, IL:  August 4, 2016. http://www.ada.org/en/press-room/news-releases/2016-archive/august/statement-from-the-american-dental-association-about-interdental-cleaners. Accessed September 21, 2021.
  5. Manchir M. ADA News: Government, ADA recognize importance of flossing. Chicago, IL: American Dental Association. August 2, 2016. http://www.ada.org/en/publications/ada-news/2016-archive/august/association-responds-to-news-story-challenging-benefits-of-dental-floss-use?nav=news. Accessed September 21, 2021.
  6. U.S. Food and Drug Administration. Code of Federal Regulations: Sec. 872.6390 Dental floss.  Revised as of April 1, 2020. http://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfCFR/CFRsearch.cfm?FR=872.6390. Accessed September 21, 2021.
  7. Beaumont RH. Patient preference for waxed or unwaxed dental floss. J Periodontol 1990;61(2):123-5.
  8. Kelekis-Cholakis A, Perry JB, Pfeffer L, Millete A. Successful treatment of generalized refractory chronic periodontitis through discontinuation of waxed or coated dental floss use: A report of 4 cases. J Am Dent Assoc 2016;147(12):974-78.
  9. Poklepovic T, Worthington HV, Johnson TM, et al. Interdental brushing for the prevention and control of periodontal diseases and dental caries in adults. Cochrane Database Syst Rev 2013(12):Cd009857.
  10. Worthington HV, MacDonald L, Poklepovic Pericic T, et al. Home use of interdental cleaning devices, in addition to toothbrushing, for preventing and controlling periodontal diseases and dental caries. Cochrane Database Syst Rev 2019;4(4):Cd012018.
  11. Sambunjak D, Nickerson JW, Poklepovic T, et al. Flossing for the management of periodontal diseases and dental caries in adults. Cochrane Database Syst Rev 2011(12):CD008829.
  12. 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.
  13. Hujoel PP, Cunha-Cruz J, Banting DW, Loesche WJ. Dental flossing and interproximal caries: a systematic review. J Dent Res 2006;85(4):298-305
Other Resources

Guidance on benefit from interdental cleaning, whether floss or other product is specified.

Last Updated: September 21, 2021

Prepared by:

Research Services and Scientific Information, ADA Library & Archives.