by Noah Orenstein DMD, MDSc, FACP

Patients have forever questioned the value of waxed versus non-waxed floss. Although non- waxed floss enables better plaque removal than waxed, people with fillings or crowns often complain about non-waxed floss tearing or ripping. As a result of this common challenge, dental floss manufacturers have developed different products to help people circumvent these issues. One of such involves a set of compounds called per- and polyfluoroalkyl substances (PFAS). Polytetrafluoroethylene, one of these PFAS substances has been added to dental floss to help the floss move between the teeth.

PFAS are a group of compounds that resist both fats and water, which is why they are used in many products including water and stain resistant fabrics, non-stick appliances and cookware, and some types of dental floss. You may have heard of one of these compounds before: polytetrafluoroethylene, otherwise known as Teflon. As these products have become more widespread, scientists have become interested in their potential health impact.

A paper recently published in the Journal of Exposure Science & Environmental Epidemiology, investigated the levels of PFAS compounds in the blood of 178 middle-aged women. The study found one of the PFAS compounds used in Glide dental floss to be higher in subjects who flossed versus those that did not. This article was picked up in the mainstream media and received a lot of attention. Although these types of articles can help to bring awareness, it is important that before drawing possibly disproportional conclusions, one has a clear understanding of the nature of the study.

In this case, the McGill University Office for Science and Society provided an analysis of the original article citing many issues:

First, they make clear the difference between finding the presence of PFAS in the bloodstream and true toxicity. As PFAS are measured at the part per TRILLION (ppt) level, just because Glide flossers were found to have a higher level of PFAS than non-flossers, does not indicate that the PFAS were present at a level of concern for true toxicity. Additionally, the authors indicate that based on the original study design, with the widespread prevalence of PFAS in our environment, there is no way to truly conclude that the compound’s presence in these subjects came exclusively from exposure to the floss.

Second, although the article was able to identify that overall, users of Glide flossers had a higher amount of PFAS in their blood stream than non-flossers, the research does not include how often people flossed, and additionally shows large ranges in the presence of these compounds. This detail limits the ability to draw a direct link between the variables. Within the actual data there were many ‘flossing’ subjects that actually had lower measured PFAS levels than ‘non-flossing’ subjects, which further weakens the validity of the data.

Given the amount of limitations to the study, we cannot conclude that Glide floss contributes to blood toxicity by PFAS, nor does it provide a reason to be concerned about changing one’s dental floss or oral hygiene patterns. That being said, this article should encourage us to continue leaning and researching the substances that are being put into our manufactured goods. Hopefully this article will contribute to more research being conducted on these topics.

So, for all of you that were hoping to use this as an excuse to stop flossing, it looks like you will have to continue searching for another reason!


Schwarcz, Joe “Is Dental Floss Toxic.” Office for Science and Society, McGill University, 18 January 2019,

K.E. Boronow, J.G. Brody, L.A. Schaider, G.F. Peaslee, L. Havas, B.A. Cohn. 2019. “Serum concentrations of PFAS’s and exposure-related behaviors in African American and non-Hispanic white women“. Journal of Exposure Science & Environmental Epidemiology. DOI: 10.1038/s41370-018-0109-y

In largest study to date using dental exams, severe periodontitis associated with 24 percent increased risk of cancer

January 16, 2018

BOSTON (Jan. 16, 2018)—Data collected during a long-term health study provides additional evidence for a link between increased risk of cancer in individuals with advanced gum disease, according to a new collaborative study led by epidemiologists Dominique Michaud at Tufts University School of Medicine and Elizabeth Platz of the Johns Hopkins Bloomberg School of Public Health and Kimmel Cancer Center.

The study, published in the Journal of the National Cancer Institute, used data from comprehensive dental exams performed on 7,466 participants from Maryland, Minnesota, Mississippi, and North Carolina, as part of their participation in the Atherosclerosis Risk in Communities (ARIC) study who were then followed from the late 1990s until 2012. During the follow-up period, 1,648 new cancer cases were diagnosed.

The research team found a 24 percent increase in the risk of developing cancer among participants with severe periodontitis, compared to those with mild to no periodontitis at baseline. Among patients who had no teeth—which can be a sign of severe periodontitis—the increase in risk was 28 percent. The highest risk was observed in cases of lung cancer, followed by colorectal cancer.

When the researchers did sub-group analyses, they found that participants with severe periodontal disease had more than double the risk of developing lung cancer, compared with no/mild periodontitis. An 80 percent increase in risk of colon cancer observed for participants who were edentulous at baseline, which is consistent with prior findings, and among never smokers, a two-fold higher risk was noted for participants with severe periodontitis, compared to those who had no/mild periodontitis.

“This is the largest study addressing the association of gum disease and cancer risk using dental examinations to measure gum disease prior to cancer diagnosis,” said first and corresponding author Dominique Michaud, Sc.D., professor of public health and community medicine at Tufts University School of Medicine. “Additional research is needed to evaluate if periodontal disease prevention and treatment could help alleviate the incidence of cancer and reduce the number of deaths due to certain types of cancer.”

Michaud noted that the findings were particularly interesting in light of research, including a recent study in Science, which determined that colorectal cancer tissues contain bacteria that are present in the mouth, including bacteria that have been associated with periodontal disease.

The researchers also uncovered a small increase in the risk of pancreatic cancer in patients with severe periodontitis. Although not significant statistically, the association has been seen in other similar studies, including a number of studies led by Michaud of Tufts.

The research team accounted for the impact of smoking among the participants, since people who smoke are more likely to get periodontal disease, and smoking raises the risk of lung and colon cancers.

“When we looked at data for the people who had never smoked, we also found evidence that having severe periodontal disease was related to an increased risk of lung cancer and colorectal cancer,” said Elizabeth Platz, Sc.D., deputy chair of the department of epidemiology at the Johns Hopkins Bloomberg School of Public Health and co-leader of the Cancer Prevention and Control Program at the Johns Hopkins Kimmel Cancer Center.

The ARIC data were especially useful to study because unlike most previous research linking gum disease and cancer risk, periodontitis cases were determined from dental examinations performed as part of the ARIC study rather than participants’ self-reports of the disease. The dental exams provided detailed measurements of the depth of the pocket between the gum and tooth in several locations in the mouth. The ARIC data include both Caucasian and African-American participants.

The researchers found no links between increased risk of breast, prostate or blood/lymphatic cancer and periodontitis. The link between periodontitis and increased cancer risk was weaker or not apparent in African-American participants from the ARIC study, except in cases of lung and colorectal cancer. “Additional research is needed to understand cancer-site specific and racial differences in findings,” wrote the authors. The researchers caution that the study was limited in size for subgroup analyses, and less common cancers. The findings, however, suggest the need for further study.

Michaud and Platz said the study also points to the importance of expanding dental insurance to more individuals. “Knowing more about the risks that come about with periodontal disease might give more support to having dental insurance in the way that we should be offering health insurance to everyone,” Platz said.

Advanced gum disease, also called periodontitis, is caused by bacterial infection that damages the soft tissue and bone that support the teeth. Previous research has shown a link between periodontitis and increased cancer risk, although the mechanism connecting the two diseases is still uncertain.

Additional authors on the study are are Jiayun Lu, John Barber, and Corinne Joshu from Johns Hopkins; Alexandra Peacock-Villada from Tufts University School of Dental Medicine; Anna Prizment from the University of Minnesota; and James Beck and Steven Offenbacher of the University of North Carolina, Chapel Hill.

This work was supported by awards from the National Cancer Institute of the National Institutes of Health (R01CA166150, P30CA006973 and U01CA164975). The Atherosclerosis Risk in Communities study, ARIC, was supported by awards from the National Heart, Lung, and Blood Institute of the National Institutes of Health, Department of Health and Human Services (HHSN268201700001I, HHSN268201700003I, HHSN268201700005I, HHSN268201700004I, HHSN268201700002I). The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.

Michaud, D.S., Lu, J., Peacock-Villada, A.Y., Barber, J.R., Joshu, C.E., Prizment, A.E., Beck, J.D., Offenbacher, S., Platz, E.A. Periodontal disease assessed using clinical dental measurements and cancer risk in the ARIC study. Journal of the National Cancer Institute (JNCI). Published online Jan. 12, 2018.

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