Since the publication last month of a New York Times article entitled, “Feeling Guilty About Not Flossing? Maybe There’s No Need,” and a similar article, “Medical Benefits of Dental Floss Unproven” by the Associated Press, we have had several lively discussions with patients about the necessity of flossing. While I agree that we should never “feel guilty about not flossing,” if the Times or the Press is suggesting that there is not an oral health benefit for flossing, we should pause and think carefully before jumping to this conclusion.

Admittedly, it is not difficult to find health information, even with the apparent weight of science supporting it, that is confusing and contradictory. For example, in the 1990’s we focused on low-fat - and today you can find a variety of suggestions about what kind and amount fat we should have in our diets.

What is important to recognize in these recent articles on flossing is this: the evidence is not contradictory. There has been no new evidence to demonstrate that flossing is ineffective, or that it is harmful. The conclusion of these meta-analyses (or surveys of the existing studies) is a rather simple recognition: the existing body of evidence does not form a clear directive for flossing as a preventative for cavities or periodontal disease. When the Department of Health and Human Services recently dropped the inclusion of a recommendation to floss, it was because a review of existing studies demonstrated “very unreliable” evidence for plaque reduction, and no statistically significant evidence for cavity prevention.

Quality studies on flossing - outside of the laboratory, over long years and with large numbers of people - face a multitude of challenges.

The primary challenge in such a long-term study is that the required conditions are nearly impossible to perform in the “real world.” Tracking at-home flossing habits for thousands of people over the span of a decade or so is a logistical impossibility. The study would then have to rely on “good faith” reporting from the subjects - and as such, removing the ability to extract absolute data, and inviting the skewed perceptions or motives to which human beings are so unilaterally prone. In other words, the people who floss are more likely to report that they do so more often, and the people who are directed not to floss are likely to report they have never done so, even if they have (in ten years, would you swear you would never retrieve a stuck popcorn kernel if necessary?)

This leads us into the second challenge of a large study: one “control” group must be directed to avoid flossing for many years - the outcome of which may be the finding that they had developed more cavities, and had developed periodontal disease. The ethical ramifications of such a directive are evidently problematic.

Lastly, the expense of such a study makes it difficult to fund. There is no government or not-for-profit agency that has volunteered the estimated $10 million minimum in capital that would be needed to power a large study, and any corporation (such as Colgate-Palmolive, or Procter & Gamble) that would be willing to foot the bill would invite criticism on the potential bias of the study. (In fact, the smaller studies that have been performed, and point to the benefits of flossing, have already been all but discounted on this very basis by various groups such as the Associated Press.)

Many of us make choices every day that improve our health and well-being in advance of science to validate it. With such widespread availability and low price point, the benefits still outweigh the potential cost of flossing. There is no question that undisturbed plaque between the teeth is a risk factor for both tooth decay and gingivitis. To quote the ADA Response: “the lack of strong evidence doesn’t equate to a lack of effectiveness.” Dental professionals have been putting their faith in the “common sense” recommendation that if we remove the bacteria from between the teeth - and remove the food that feeds it - that our gums and teeth will feel better, look better, and smell better. When the potential benefit is so high-stakes as the prevention of decay and periodontal disease, flossing is almost certainly worth the 2 minute daily time investment.

Until have a better proven way to disrupt the plaque, interdental cleaning with floss will remain an essential part of good oral hygiene. We look forward additional quality research which demonstrates the preventative benefits of effective flossing on tooth and gum health. In the meantime, we will keep flossing - and encouraging you to do the same.