To Floss or Not to Floss?

Dr. V Kim Kutsch

Dental floss made from silk thread first became a commercial product in 1882 and has probably been a controversial topic since day one. The dental profession routinely recommends patients floss daily and dental hygienists daily instruct patients on flossing technique as a standard of care. Despite the profession’s continued efforts, self-care with dental floss has a very low adoption rate. The news media widely reported the results of a recent Associated Press examination of scientific evidence from a Freedom of Information Act request with the Human Health and Services. Upon receiving a letter from HHS acknowledging that this topic has not really been studied, the AP then examined 25 studies and found little or no scientific evidence to support flossing. So why floss?

The theory behind flossing is that tooth brushing does not reach into the interproximal region between teeth and daily flossing to disrupt the biofilm will improve the outcomes in dental caries and periodontal disease. While the theory is logical and intuitive, flossing is a difficult habit to establish, is technique sensitive and depends completely on patient adherence for any outcome.

Unfortunately, the AP report was mostly right. There is as yet little scientific evidence to support daily flossing providing any benefit.1,2 A search of Pubmed provides studies that demonstrate flossing adds little to no additional benefit to tooth brushing. One report did demonstrate a significant improvement with interdental brushing compared with flossing.3  A recent study even demonstrated improved outcomes in four patients with refractory periodontal disease when they stopped flossing.4 The evidence indicates one cannot simply brush and floss dental diseases away. So, should we all stop flossing? What is the risk versus the benefit?

Dental caries and periodontal disease are both multifactorial biofilm-based diseases. They are frustrating diseases for both patients and the dental professionals treating them. Since the biofilm is one of the risk factors in both diseases, it still makes sense to disrupt that biofilm on a daily basis. While most studies demonstrate little to no evidence, there are a few that do.5 One study clearly demonstrated improved outcomes with dental caries bacteria6, while another study utilized daily professional flossing on students.7  The National Institutes of Health (the NIH), in response to articles like the one referenced here, urged patients not to give up flossing and pointed out that 12 well-controlled studies have found brushing and flossing together can reduce gingivitis, mild gum disease.

While it is clear that the use of floss needs better scientific investigation, it’s important to remember what that really means. Lack of high-quality evidence in favor of flossing at this point does not mean flossing doesn’t work. While no study with high-quality evidence exists to definitely prove flossing works, there is no high-quality study proving flossing doesn’t work. We have speculation, we have soft evidence, but we just haven’t collected hard evidence one way or the other.

I will still floss, and I will recommend it for my patients as a part of my complete approach of risk assessment based care. I will still focus on helping patients understand the causes of their diseases and helping them establish targeted therapies to reduce their risks.



  1. 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 Nov 2008. 6(4):265-79.
  2. Dorri M, Dunne SM, Walsh T, Schwendicke F. Micro-invasive interventions for managing proximal dental decay in primary and permanent teeth. Cochrane Database Syst Rev 2015 Nov. 5(11).
  3. Salzer S, Slot DE, Van der Weijden FA, Dorfer CE. Efficacy of inter-dental mechanical plaque control in managing gingivitis—a meta-review. J Clin Periodontol April 2015. 42 Suppl 16:S92-105.
  4. Wilder RS, Bray KS. Improving periodontal outcomes: merging clinical and behavioral science. Periodontol 2000 June 2016. 71(1):65-81.
  5. Chapple IL, Van der Weijden F, Doerfer C, et al. Primary prevention of periodontitis: managing gingivitis. J Clin Periodontol April 2015. 42 Suppl 16:S71-6.
  6. Corby PM, Biesbrock A, Bartizek A, et al. Treatment outcomes of dental flossing in twins: molecular analysis of interproximal microflora. J Periodontol. August 2008. 79(8):1426-33.
  7. Hujoel PP, Cunha-Cruz J, Banting DW, Loesche WJ. Dental flossing and interproximal caries: a systematic review. JDR April 2006. 85(4):298-305.

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