Is Flossing Necessary? Here’s What You Need To Know!

Is Flossing Necessary? Here's What You Need To Know!

There has been a lot of discussion about whether flossing is necessary for good oral health. In this article, I’ll review a flossing related encounter I had with a patient of mine as well as dive into the details of the anti-flossing research that’s been recently cited in the news.

The patient who stopped flossing

I recently found out that a very aware and well-informed patient of mine stopped flossing. She reported reading evidence-based news reports that stated flossing is a waste of time and doesn’t really work. She referenced articles from publications such as the New York Times, the Guardian, and the Daily Mail – all of which she looked up online and showed me on her phone during her appointment.

To my surprise, she was right! There were multiple news reports that quoted what appeared to be high-quality research. I informed her that I would get back to her at her next appointment, once I read and understood the research behind it. I also informed that personally, it was hard to believe this news – but I would look into the evidence as an unbiased consumer, to understand the issue from her point-of-view, and educate myself as well.

Reviewing the anti-flossing news reports

I looked into the news reports and followed the links to the research articles that they provided. I read every one of those articles. They were based on 2 systematic reviews. One was in the Cochrane Database of Systematic Reviews while the other was published in the Journal of Clinical Periodontology.

Note: Links to the reports can be found in the references below.

The news reports quoted the exact words below followed by what this statement means to them:

“There is weak, very unreliable evidence from 10 studies that flossing plus toothbrushing may be associated with a small reduction in plaque at 1 and 3 months.”

What does “weak, very unreliable” evidence really mean?

Cochrane reviews use the GRADE approach (Grades of Recommendation, Assessment, Development, and Evaluation), which is a way that investigates the quality and quantity of the evidence.

“Weak” comes from the GRADE approach, which says that the quality of the studies, collectively, based on the objective assessments do not allow us to make a strong recommendation. The grading scale goes from high, moderate, weak, and very weak recommendation.

Then, “very unreliable” comes collectively from the GRADE approach and Cochrane RoB (Cochrane Risk of Bias) tool.

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How the flossing research was misleading

The reviews mostly looked into plaque and gingival as outcome measures. In particular, they assessed how they were affected by flossing.

Having no research evidence for something does not mean that there is no research evidence at all! In the case of flossing, we do have evidence. Although it is low quality, it establishes that flossing is beneficial in reducing plaque, which is all we need to know.

I went through all the other systematic reviews on the subject, to find only mixed results. The quality of the reviews also varied, and it is very important to have high-quality reviews in oral health care.

At the next appointment with the patient, I was able to convince her about the importance of flossing. I also explained to her, in laymen terms, what these studies really meant.

What did I learn from this experience?

We live in the age of information revolution! In fact, information is now available at a single click of the mouse or tap of a finger. Sometimes, the language of research literature is misinterpreted and ideas are wrongly reported by news reports.

As a dentist, my colleagues and I should be able to make sense of the literature as well as have the patience to explain it in simplified terms to our patients.

So, is flossing necessary?

Honestly, yes! I recommend that all of my patients floss routinely. Flossing is beneficial in reducing plaque which can cause cavities. Doing so can prevent invasive and costly treatments down the road.

If you have any questions, comments or concerns about flossing, feel free to leave them in the comments below!


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  6. 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.
  7. Sälzer S, Slot DE, Van der weijden FA, Dörfer CE. Efficacy of inter-dental mechanical plaque control in managing gingivitis–a meta-review. J Clin Periodontol. 2015;42 Suppl 16:S92-105.
  8. 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.
  9. Alderson P. Absence of evidence is not evidence of absence. BMJ. 2004;328(7438):476-7.
  10. Matthews D. Weak, unreliable evidence suggests flossing plus toothbrushing may be associated with a small reduction in plaque. Evid Based Dent. 2012;13(1):5-6.
  11. Chapple IL, Van der weijden F, Doerfer C, et al. Primary prevention of periodontitis: managing gingivitis. J Clin Periodontol. 2015;42 Suppl 16:S71-6.
  12. Djulbegovic B, Kumar A, Kaufman RM, Tobian A, Guyatt GH. Quality of evidence is a key determinant for making a strong GRADE guidelines recommendation. J Clin Epidemiol. 2015;68(7):727-32.
  13. Brozek JL, Akl EA, Alonso-coello P, et al. Grading quality of evidence and strength of recommendations in clinical practice guidelines. Part 1 of 3. An overview of the GRADE approach and grading quality of evidence about interventions. Allergy. 2009;64(5):669-77.
  14. Agnihotry A, Fedorowicz Z, Worthington HV, Manheimer E, Stevenson RG. Systematic reviews in oral health: A quality imperative. J Evid Based Med. 2016;9(2):47.
  15. Higgins JP, Altman DG, Gøtzsche PC, et al. The Cochrane Collaboration’s tool for assessing risk of bias in randomised trials. BMJ. 2011;343:d5928.
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Anirudha Agnihotry, DDS
Dr. Anirudha (Anir) Agnihotry graduated from Manipal College of Dental Sciences with a Bachelor's in Dental Surgery (BDS) Degree in 2012. After a one year clinical internship, he joined the faculty at Operative Dentistry and Endodontics Department in Mahatma Gandhi Dental College, where he also maintained a faculty practice. He later moved to Divya Jyoti College of Dental Sciences and Research in the Public Health Dentistry, where he trained dental students as well as worked in setting up community outreach clinics and school oral health programs. In 2014, he moved to US where he completed a post-graduate certificate training in restorative dentistry and worked as a researcher at UCLA. He later enrolled in an intense accelerated program to get a Doctor of Dental Surgery (DDS) Degree in 2 years, from where he graduated in 2018. He has been in dentistry for 11 years and has published 11 international scientific research papers, presented in international conferences, and is also a referee for 5 international scientific journals. His main focus is patient-centered outcomes and secondary research with a focus on clinical outcomes. Apart from dentistry, he enjoys swimming, playing squash, running, biking, barbecuing, and art of all forms.