Dental flosses made from polytetrafluoroethylene, commonly known as PTFE or Teflon, are the primary floss products that contain PFAS. The most widely recognized brand in this category is Oral-B Glide, but independent testing has also detected fluorine in store-brand flosses marketed as Glide alternatives. Nylon flosses, silk flosses, and water flossers avoid the issue entirely, and at least one peer-reviewed study has linked Glide-type floss use to measurably higher levels of certain PFAS chemicals in users’ blood. The distinction between safe and problematic floss comes down to material, and it is easier to spot than you might expect.
Why PTFE Flosses Contain PFAS
PFAS stands for per- and polyfluoroalkyl substances, a large family of synthetic chemicals built around carbon-fluorine bonds. PTFE is itself a member of the PFAS family, and dental floss made from it inherits the chemistry. PTFE floss glides between teeth more easily than nylon because its surface is extremely smooth. A comparison of four floss materials found that PTFE floss had the lowest surface roughness of any type tested, which is exactly why users tend to prefer it, and also why it was rated the most pleasant to use in subjective preference surveys.1PubMed Central. Comparison of dental flosses – an investigation of subjective preference and mechanical properties That slippery quality is a direct product of fluorine chemistry. Some flosses that are not made entirely of PTFE are still coated with PFAS-containing compounds to reduce friction as the strand passes between contacts.
This means the PFAS in dental floss is not an accidental contaminant. It is the product itself, or at minimum a deliberate coating. The fluorine is baked in by design. And because floss is used inside your mouth, pressed against gum tissue that can be nicked or inflamed, it raises a question most people have never considered: does flossing with PTFE products actually introduce these chemicals into the body?
Which Specific Products Tested Positive
The most detailed product-level testing comes from a study that used particle-induced gamma-ray emission analysis to measure total fluorine in 18 commercially available dental floss products. Fluorine was detected in six of the 18, including all three products branded as Oral-B Glide and two of three store-brand flosses whose labels invited consumers to “compare to Oral-B Glide.” The fluorine concentrations in these positive samples ranged from roughly 1,000 to 3,000 counts per microcoulomb.2Journal of Exposure Science & Environmental Epidemiology. Serum concentrations of PFASs and exposure-related behaviors in African American and non-Hispanic white women The remaining 12 products, which were made from nylon or other non-fluorinated materials, showed no detectable fluorine.
The takeaway from this testing is straightforward: the word “Glide” on the label, or a claim that the floss is comparable to Glide, is a reliable flag. Products described as PTFE or Teflon floss fall into the same category. If the packaging says nylon, silk, or does not mention PTFE, the floss almost certainly does not contain PFAS. There is no comprehensive database of every floss brand, but the material composition printed on the packaging gives you what you need.
Evidence That PTFE Floss Raises PFAS Blood Levels
Two separate studies have connected dental floss use to measurable changes in serum PFAS concentrations, though the picture is more nuanced than a simple “flossing is dangerous” headline.
The first, which examined behavioral predictors of PFAS blood levels in a cohort of African American and non-Hispanic white women, found that flossing with Oral-B Glide specifically was associated with roughly 25% higher serum levels of PFHxS, a particular PFAS compound, compared to women who did not use that brand.2Journal of Exposure Science & Environmental Epidemiology. Serum concentrations of PFASs and exposure-related behaviors in African American and non-Hispanic white women That is not a trivial bump. PFHxS is one of the more persistent PFAS compounds and has drawn regulatory attention in multiple countries.
A second, larger cross-sectional study using national health survey data found that dental floss users in general had higher serum concentrations of PFOA compared with non-users, and the difference was statistically significant after adjusting for other variables. Interestingly, the same study found that floss users actually had lower blood levels of several other PFAS compounds, including PFDA, PFHxS, PFOSA, and MeFOSAA.3PubMed Central. Association Between Serum Levels of Perfluoroalkyl and Polyfluoroalkyl Substances and Dental Floss Use – Section: RESULTS The authors described this as a “double-edged sword” finding: the PFOA increase was concerning, but the overall PFAS profile was mixed rather than uniformly worse.
Neither study could pin down exactly how PFAS moves from floss into the bloodstream. One possibility is that tiny amounts of PTFE or its breakdown products transfer to oral tissues during use, especially when flossing causes micro-injuries to the gums. A narrative review of microplastics in the oral cavity noted that the mechanical action of flossing can cause gingival bleeding, potentially allowing plastic debris and chemicals released from the floss to come into direct contact with the bloodstream through the gum tissue.4PubMed Central. Micro- and Nanoplastics and the Oral Cavity: Implications for Oral and Systemic Health, Dental Practice, and the Environment – Section: Toothpaste, Toothbrushes, Dental Floss, and Mouthwashes This remains speculative. Researchers have noted that the exact mode by which PFAS from dental floss enters serum has not been established and warrants future study.1PubMed Central. Comparison of dental flosses – an investigation of subjective preference and mechanical properties
Why PFAS Exposure Matters
PFAS chemicals are sometimes called “forever chemicals” because they do not break down in the environment or in the human body on any practical timescale. Their half-lives in human blood are measured in years, not days. The concern is not that a single flossing session will poison you, but that daily use over years adds to a cumulative body burden of chemicals that your body cannot clear quickly.
The health effects under investigation are broad. PFAS compounds have been identified as endocrine disruptors, meaning they can interfere with hormonal signaling even at low concentrations, contributing to a range of health disorders.5PubMed Central. Endocrine Disruptor Potential of Short- and Long-Chain Perfluoroalkyl Substances (PFASs)-A Synthesis of Current Knowledge with Proposal of Molecular Mechanism A systematic review and meta-analysis found that PFAS exposure was significantly associated with altered reproductive hormone levels in humans.6PubMed. Association between exposure to per- and perfluoroalkyl substances (PFAS) and reproductive hormones in human: A systematic review and meta-analysis And increasing evidence suggests that even low-level, chronic exposure can disrupt endocrine function in women specifically.7PubMed Central. PFAS Exposure and Endocrine Disruption Among Women
To put this in proportion, dental floss is one of many PFAS exposure sources. People encounter these chemicals through nonstick cookware, food packaging, waterproof clothing, contaminated drinking water, and firefighting foam residues. Floss is unlikely to be anyone’s single largest source. But it is one of the easiest to eliminate, because non-PFAS alternatives work just as well, which brings us to the practical question most people land on next.
Does Switching Away From PTFE Floss Mean Worse Cleaning?
No. This is one of the most reassuring findings in the research. A controlled study comparing PTFE tape to standard nylon dental floss in adolescents and young adults measured the amount of plaque remaining between teeth after use. The PTFE group went from about 73% plaque presence to 11% after flossing. The nylon group went from about 73% to 11.2%. The difference between the two was not statistically significant.8Colombia Médica. Price and the efficacy of the polytetrafluoroethylene (PTFE) tape for the removal of the proximal dental biofilm compared to the common nylon dental floss in adolescents and young adults In other words, PTFE’s slick surface does not translate into better plaque removal. It just feels smoother while doing the same job.
PTFE floss is popular because of that smooth feeling, and because it resists shredding between tight contacts. The mechanical properties back this up: PTFE has the lowest surface roughness of the tested floss types, which makes it feel frictionless.1PubMed Central. Comparison of dental flosses – an investigation of subjective preference and mechanical properties But that same study found PTFE had the lowest tensile strength, meaning it is actually the weakest floss material in terms of resistance to snapping. If you have been choosing PTFE floss because you assumed it was a premium product, the data suggest it is really just the most pleasant-feeling option, not the most effective or durable one.
How to Choose a PFAS-Free Floss
The shopping strategy is simple once you know what to look for. Avoid products that:
- Name PTFE or Teflon: These are the same material and inherently contain PFAS.
- Are branded as Glide: All tested Glide products contained high fluorine levels.
- Claim to be “comparable to Glide”: Two of three such products in independent testing also tested positive for fluorine.
Products that are generally PFAS-free include traditional waxed or unwaxed nylon flosses, silk flosses, and flosses made from ultra-high-molecular-weight polyethylene (UHMWPE). Many natural and eco-friendly brands explicitly market themselves as PFAS-free and use materials like silk with plant-based wax coatings. If a product’s ingredients list or packaging mentions only nylon, silk, or polyethylene, you are almost certainly in the clear.
One thing worth watching for: some nylon flosses have PTFE coatings to make them glide more easily, even though the base material is nylon. If a nylon floss feels unusually slick and the label is not explicit about its coating, it is worth checking the manufacturer’s website or choosing a brand that advertises itself as PFAS-free. Transparency on this issue has improved significantly in recent years, and many companies now list their floss material clearly.
Water Flossers as an Alternative
If the PFAS question makes you rethink your flossing routine entirely, water flossers sidestep the issue while potentially offering better cleaning performance. A systematic review found that the majority of studies favored water flossers over dental floss for plaque reduction, with four of the included studies showing significantly better results. Water flossers were particularly effective at reaching inaccessible areas between teeth compared to string floss.9PubMed Central. Comparing the effectiveness of water flosser and dental floss in plaque reduction among adults: A systematic review Three other studies in the same review found no significant difference, but none found floss to be superior.
Around dental implants, the advantage is more pronounced. A study comparing water flossers to string floss around implants found that after 30 days, 18 of 20 implants in the water flosser group showed reduced bleeding, compared to only 6 of 20 in the string floss group, roughly a threefold difference.10PubMed Central. Comparison of the Impact of Two Interdental Cleaning Devices on the Reduction of Bleeding Around Implants Water flossers obviously contain no PFAS, no microplastics, and no string to shred. Their main drawbacks are cost and the fact that they require a power source and water reservoir.
Interdental brushes are another solid option, especially for people with wider gaps between teeth. They do not involve PFAS, and dental professionals often recommend them for people with braces or bridgework. The best interdental cleaning tool is ultimately whichever one you will actually use consistently.
Microplastics and Other Concerns From Floss Materials
PFAS is not the only material concern with dental floss. Most conventional flosses, whether PTFE or nylon, are made from non-biodegradable, non-recyclable plastics. A narrative review on microplastics in the oral cavity noted that dental floss is typically manufactured from materials associated with single-use plastic pollution, and that PFAS-containing coatings on some products may leach out during decomposition or release directly into the mouth during use.11PubMed Central. Micro- and Nanoplastics and the Oral Cavity: Implications for Oral and Systemic Health, Dental Practice, and the Environment
The review raised an interesting point about what happens at the gum line: the physical action of flossing can create micro-injuries, and tiny particles of plastic shed from the floss strand could theoretically contact gingival tissue and even enter the bloodstream through inflamed or bleeding gums. This is still largely hypothetical, and nobody has demonstrated that microplastic ingestion from floss causes specific harm. But for people who are trying to reduce their overall plastic and chemical exposure, switching to silk floss with natural wax, or to a water flosser, addresses both the PFAS and the microplastic question simultaneously.
Putting Floss PFAS in Context With Other Dental Products
You might wonder whether other dental products carry similar PFAS risks. A study that tested night guards and whitening trays for 24 different PFAS compounds found that whitening trays contained no detectable PFAS at all. Night guards did contain small amounts of two PFAS compounds, PFBA and PFOS, but at levels the researchers concluded were unlikely to pose a health concern. From an environmental standpoint, the dental products examined were described as a negligible contribution to overall PFAS pollution.12SAGE Journals (Toxicology and Industrial Health). Assessing potential human health and ecological implications of PFAS from leave-in dental products
This is useful context. The dental product most likely to expose you to PFAS is specifically PTFE floss, not your night guard, retainer, or whitening trays. And even with PTFE floss, the exposure is a fraction of what you might get from contaminated drinking water or years of cooking with degraded nonstick pans. The argument for switching away from PTFE floss is less about panic and more about practicality: the swap is easy, the alternatives clean your teeth just as well, and there is no reason to add to your PFAS burden from a source that is trivially avoidable.
Why Researchers Are Still Cautious About Drawing Hard Conclusions
The existing research has real limitations that are worth understanding. The studies linking Glide-type floss to higher PFAS blood levels are observational, meaning they cannot prove that the floss caused the higher levels. People who use Oral-B Glide may also share other lifestyle factors, like using more nonstick cookware or living in areas with different water supplies, that independently affect their PFAS exposure. The cross-sectional study that found higher PFOA in floss users acknowledged this limitation by describing its results as an association, not a confirmed causal pathway.3PubMed Central. Association Between Serum Levels of Perfluoroalkyl and Polyfluoroalkyl Substances and Dental Floss Use – Section: RESULTS
Additionally, nobody has run a controlled experiment where one group flosses with PTFE and another with nylon for a year, then measures whether the PTFE group’s PFAS levels climb. That kind of study would be ethically tricky to design now that the concern is public. So we are left with correlational data, plausible mechanisms involving oral tissue absorption, and the straightforward chemical fact that PTFE is a fluorinated polymer. The evidence is strong enough to make switching a sensible precaution but not strong enough for anyone to claim that PTFE floss definitively causes measurable health harm. Researchers have explicitly called for more work to establish the modes by which PFAS from floss enters the bloodstream, and until that work is done, some uncertainty will remain.
For most people, the practical calculus is uncomplicated. You are not going to stop flossing, and you should not stop flossing. Gum disease and tooth decay are well-established, serious health problems, and the benefit of interdental cleaning is not in question. The question is simply which string you drag between your teeth, and the answer is any string that is not made of PTFE.