Short answer
- Most dental floss is made of nylon or PTFE. Nylon is a multifilament, many thin strands twisted together. PTFE is a monofilament, a single strand of polytetrafluoroethylene, a slippery synthetic polymer.
- Silk and plant based flosses also exist. Silk is the traditional natural fiber. Newer options use fibers such as corn or bamboo, usually with a plant wax coating.
- Coatings mainly change feel, not cleaning power. Wax helps floss slide and resist shredding. Flavorings such as mint add freshness. Neither makes floss clean better.
- Waxed and unwaxed floss clean in the same basic way. Waxed is often easier through tight contacts. Unwaxed is thinner and can grip more. Fit and preference matter more than any proven cleaning difference.
- PTFE belongs to the fluoropolymer family discussed under the wider PFAS heading, and the evidence is unsettled. A 2019 study found an association between reported use of one PTFE floss and higher levels of one PFAS chemical in blood. The American Dental Association said the data were insufficient to support the conclusions drawn, and it continues to recommend daily cleaning between teeth.
- Technique matters more than material. Clean between teeth once a day, curving floss into a C shape against each tooth and moving it gently up and down below the gum line. If the PTFE question worries you, nylon, silk, and plant based flosses clean in the same way with good technique.
Introduction
Dental floss looks like one of the simplest products in a bathroom: a length of thread in a small plastic box. Yet the thread can be made from quite different materials, and those materials explain most of the differences people notice in use. One floss glides through a tight gap without effort. Another grips, squeaks, and then shreds on a rough filling. One feels thick and cushioned, another thin and sharp. Those differences are not marketing. They come from what the floss is made of and what has been put on its surface.
This article explains the main floss materials, nylon, PTFE, silk, and newer plant based fibers, and what coatings such as wax and flavoring actually do. It also looks calmly at the question many readers arrive with: whether PTFE floss raises a PFAS concern, and what the studies and the American Dental Association have actually said about it, in the measured terms those sources use.
Two limits apply throughout. First, this is general oral hygiene information only. It is not advice for your own mouth, and it does not replace your dentist or hygienist, who can see your teeth, your gaps, and any dental work you have. Second, the cleaning benefit of floss comes mainly from physically disrupting plaque between teeth. Material choice affects comfort, glide, and whether you keep up the habit. It does not turn one floss into a medicine and another into a risk on its own.
Why Floss Exists: The Job Between Teeth
A toothbrush does not fully clean the surfaces where two teeth touch or just below the gum line between them. The American Dental Association makes that point on its MouthHealthy flossing page: brushing twice a day for two minutes is the first step, but even the best toothbrush cannot fully cleanse the spaces between teeth, which is why the association recommends flossing once a day.
What collects there is plaque, the sticky film of bacteria that forms on teeth. MouthHealthy explains that plaque bacteria feed on leftover food, especially sugars, and produce acids that can harm the tooth surface and set the stage for decay. Plaque that is not removed can harden into tartar, which builds up along the gum line and can lead to gum disease. Once tartar forms, only a dentist can remove it.
The NHS gives the same picture: regular flossing may reduce gum disease, tooth decay, and bad breath by removing plaque along the gum line. For what decay looks like once it starts, see our guide to what a cavity looks like. Material is a practical question too: a floss that shreds in your tightest gap is a floss you will quietly stop using.
The Two Constructions: Multifilament and Monofilament
Construction explains behavior as much as chemistry does. A peer reviewed study in the journal Materials in 2022 groups flosses as monofilaments and multifilaments, waxed and unwaxed, and synthetic and natural. A monofilament is one strand. A multifilament is several strands twisted together.
A bundle of fine strands can flatten against a tooth, but the strands can also separate and catch on a rough edge, which is why multifilament floss sometimes frays or shreds. A single solid strand has nothing to separate, so it stays intact and slides, but can feel like a smooth ribbon rather than a scrubbing thread. Neither is simply better.
Shape matters too. Standard floss is roughly round. Dental tape is wider and flatter, with a rectangular profile. Tape covers more surface per pass and can feel gentler in wider gaps, while thin round floss fits more easily where teeth are crowded.
Nylon: The Most Common Floss Material
Nylon floss is the traditional and still most common type: many thin strands twisted together into a single thread. The Materials study describes synthetic floss as made of nylon or PTFE, and notes that nylon offers very low friction while remaining relatively durable. It is flexible, widely available, and sold waxed and unwaxed, flavored and unflavored.
Its weakness follows from its construction. Separate strands can shred or fray where teeth are very tight, where a filling has a rough edge, or where a contact point is uneven. A strand catches, the bundle separates, and the floss breaks or leaves fibers behind. For people with crowded teeth or older dental work, that can happen often enough to put them off flossing.
Unwaxed nylon is the thinnest version. Its strands can spread a little against the tooth, and some users like the firmer grip and slight squeak. That squeak is a feel, not proof of a better clean. Waxed nylon passes through tight contacts with less catching and generally resists shredding better. If your gums are sore when you start, material is rarely the cause on its own: our article on swollen gums after flossing explains early soreness and bleeding, and which signs need a dental check.
PTFE: The Single Strand Glide Floss
PTFE floss is made from polytetrafluoroethylene, the slippery synthetic polymer best known as the coating family used on nonstick pans. It is a monofilament, one continuous strand. With no separate fibers to catch and split, it slides through tight contacts easily and rarely shreds. The Materials study notes that PTFE is slightly more tolerant to elongation than nylon, which fits its stretchy feel. MouthHealthy describes traditional floss as a smooth strand of nylon or Teflon, using the familiar brand name for the same polymer family.
PTFE floss is often sold as glide or shred resistant floss, and tape versions are common. For people whose nylon floss breaks repeatedly, that easy glide can be the difference between flossing daily and not flossing at all.
The trade offs are worth naming. A very slippery strand can feel as though it slides over the tooth rather than wiping it, so it still needs to be curved against the tooth and moved up and down. PTFE also does not break down in the environment the way a natural fiber can, and it is the material at the center of the PFAS discussion below. Readers who prefer to avoid fluoropolymers have workable alternatives, which is part of why the choice can stay calm.
Silk and Plant Based Flosses
Silk is the original floss material, and silk floss is still sold today, usually waxed. The Materials study classifies silk as the natural option, in contrast to synthetic nylon and PTFE. Silk fibers are biodegradable in a way synthetics are not, but silk can fray more readily than a monofilament and usually costs more than standard nylon.
Newer plant based flosses use fibers from sources such as corn or bamboo, typically coated with a plant wax such as candelilla wax, which the Materials study lists alongside the more usual synthetic wax coatings. These products suit people who want to reduce synthetic fiber use in a daily habit.
One caution applies: compostable claims depend on the whole product, not just the fiber. A plant fiber coated in synthetic wax, in a plastic container, is not the same as an uncoated natural fiber. Check the packaging and what local composting accepts. None of this affects cleaning.
Floss Picks and Holders: Same Materials, Different Format
Floss picks hold a short length of floss, nylon or PTFE, on a plastic handle. MouthHealthy notes that dental picks can be good for reaching out of the way spots, and pre threaded flossers are among the options people can try. For anyone who finds wrapping floss around their fingers difficult, a handle can make daily cleaning realistic.
The material questions are identical, because the working part is the same thread. The differences are practical. One short segment serves the whole mouth, so rinse the pick as you go and replace it when it frays. Picks also use more plastic per clean than string floss. If a pick is the format that gets you cleaning between your teeth every day, that benefit outweighs these drawbacks for most people.
What Coatings Do: Wax, Flavoring, and the Rest
Wax coatings
Wax is the most common coating and the one with the clearest job. The Materials study notes that wax coating is usually synthetic, while some natural options use candelilla wax, and beeswax is also used on natural fiber flosses. Wax helps floss slide through the contact point, reduces catching and shredding, and makes the thread feel smoother and slightly thicker. That is the whole of its role. Wax does not remove plaque by itself, and waxed floss is not medicated.
Flavorings
Mint and other flavorings make flossing feel fresher. The benefit of flossing, as both the ADA and the NHS frame it, is removing plaque and food particles, and flavoring plays no part in that mechanism. A flavor you like may help you keep the habit, which is a genuine if indirect benefit. It does not clean better, and unflavored floss is not a lesser product.
Fluoride and other added coatings
Some flosses are marketed with fluoride, others with charcoal or antibacterial style claims. The main, established benefit of flossing is mechanical: physically disrupting and removing plaque from surfaces a brush cannot reach. Any coating benefit is at most secondary, and evidence that specialty coatings add meaningful benefit beyond ordinary floss used well is limited. Your toothpaste remains the main topical fluoride source in a normal routine.
Waxed vs Unwaxed: Does It Change the Clean?
The answer is reassuringly dull. Waxed and unwaxed floss work by the same mechanical action. The differences are fit and feel. Waxed floss is slightly thicker but slides more easily, so it often suits tight contacts and beginners, and the wax holding the strands together resists shredding. Unwaxed floss is thinner, can fit where waxed feels bulky, and some people prefer its grip, but it frays more easily on rough edges. Dental tape suits wider gaps.
Try both in your own tightest gap. If one shreds or feels impossible, switch type before you switch off the habit. The floss you use daily will do more for your gums than the ideal floss sitting unused in a drawer.
PTFE and PFAS: The Question, in the Terms the Sources Use
PTFE is a fluoropolymer, and fluoropolymers are discussed as part of the wider family of per and polyfluoroalkyl substances, known as PFAS: synthetic chemicals valued for resisting water, grease, and friction, the same slipperiness that makes PTFE useful in floss. It is reasonable to ask whether using a PTFE strand daily is an exposure worth thinking about. On the sources below, the research is limited and unsettled, and no major dental authority has told people to stop cleaning between their teeth over it.
What the 2019 study found
The study most often cited is a peer reviewed paper by Boronow and colleagues, published in the Journal of Exposure Science and Environmental Epidemiology in 2019. The researchers measured 11 PFAS chemicals in blood from 178 middle aged women and asked about behaviors that might affect exposure. Women who reported flossing with a named PTFE based glide floss tended to have higher levels of one PFAS, PFHxS, or perfluorohexanesulfonic acid, than women who did not. The team also tested 18 flosses for fluorine, a marker of fluorinated material, and found fluorine in the glide products tested, consistent with Teflon like compounds.
That is an association, not proof that floss caused the higher levels, and not a finding about health effects. PFAS exposure can also come from food packaging, stain resistant treatments, drinking water, and other products the study examined.
What the ADA said in response
The American Dental Association responded in January 2019 through its Science Institute, saying it found the data insufficient to support the conclusions presented. It pointed to specific limitations: a single, small, retrospective study based on self reported product use, and fluorine measured as a marker of PTFE even though the chemical raised in blood was PFHxS, a different substance. Finding a PTFE marker in floss does not establish floss as the PFHxS source. It also noted that no restrictions on dental floss use had been issued by the US Food and Drug Administration, and that safety decisions should rest on the collective weight of evidence.
Its more recent position, in its own news coverage of state PFAS legislation, is the same: the ADA is monitoring PTFE in oral care products, to date sees no cause for concern on current evidence, and maintains its recommendation to clean between teeth daily.
A balanced way to act on unsettled evidence
Three things can be true at once. The 2019 association is a real finding and a legitimate reason for further research. The ADA’s criticisms are also specific and substantive. And the harms of never cleaning between teeth are well established rather than hypothetical: see our explainer on the signs of gum disease.
If the question still bothers you, the practical response costs nothing: choose a nylon, silk, or plant based floss. You lose no cleaning benefit, because effectiveness depends on daily use and technique, not the polymer. What the evidence does not support, in either direction, is certainty. Bring specific concerns to your dentist.
Alternatives to String Floss, in General Terms
String floss is not the only way to clean between teeth. MouthHealthy lists dental picks, tiny brushes, and water flossers alongside traditional floss, and advises talking with your dentist and trying options to find the one you like best. The NHS likewise says interdental brushes or single tufted brushes can be used instead of flossing, especially where there are gaps, and that a brush should fit snugly.
Interdental brushes need a gap wide enough to accept them without force, and they come in sizes, which is why a hygienist’s sizing advice helps. Water flossers rinse away food and plaque with a stream of water, and MouthHealthy notes they can help people who find other tools hard to use, including people with braces, bridges, and other dental work.
The comparative evidence is more modest than marketing suggests. A Cochrane review of 35 studies concluded that floss or interdental brushes plus toothbrushing may reduce gum inflammation or plaque more than toothbrushing alone, and that brushes may be better than floss for gum inflammation at one and three months, on low to very low certainty evidence, mostly short term. Choose the tool that fits your gaps and your hands. The rest of the routine still applies, including care for the tongue, covered in why you should be brushing your tongue, and an eye on acidic drinks, discussed in sparkling water vs still water for teeth.
Technique Matters More Than Material
Most floss problems are technique problems, so the ADA’s five step method is worth following. Break off about 18 inches of floss and wind most of it around one middle finger, the rest around the same finger of the opposite hand, so you can work with a clean section in each gap. Hold it tightly between thumbs and forefingers, guide it between the teeth with a gentle rubbing motion, and never snap it into the gums. At the gum line, curve it into a C shape against one tooth, slide it gently between gum and tooth, and rub the side of the tooth with up and down motions. Repeat in every gap, including the back of the last teeth.
The NHS method is the same in substance: 30 to 45 centimeters of floss or tape, 3 to 4 centimeters taut, curved into a C shape and slid gently up and down. The NHS adds that it is best to floss before brushing. MouthHealthy is more relaxed on order: thorough daily flossing matters most.
Cleaning between teeth should not cause pain. Slight bleeding in the first days usually settles as inflammation improves. Persistent bleeding, pain, or floss that always shreds on the same tooth are reasons to see a dentist. Our guide to how to remove plaque from teeth explains which plaque you can shift at home and which deposits only a professional can remove.
How to Read a Floss Label
Look for the base material first: nylon, PTFE, silk, or a named plant fiber. Glide or shred resistant wording usually signals a PTFE monofilament, though only the maker’s disclosure confirms it. Note whether the floss is waxed, and with what: beeswax and candelilla wax appear on natural fiber products, while standard waxed floss usually uses a synthetic wax. Treat flavor as a preference, and coating claims such as charcoal or antibacterial as marketing unless the maker points to real evidence.
Also look for the ADA Seal of Acceptance. MouthHealthy states that products carrying it have been shown to be safe and effective. The seal does not answer the PTFE question for you, since it reflects the ADA position above, but it tells you a product met the association’s standards for its stated job.
Frequently Asked Questions
What is dental floss made of?
Most floss is nylon or PTFE. Nylon is a multifilament, many thin strands twisted together, sold waxed or unwaxed. PTFE is a single monofilament strand of polytetrafluoroethylene, often sold as glide or tape floss. Silk and plant based flosses, from fibers such as corn or bamboo, are also available, usually with a natural wax coating.
Is PTFE floss the same as Teflon floss?
Effectively, yes. Teflon is the best known brand name for PTFE, and MouthHealthy describes traditional floss as a smooth strand of nylon or Teflon. A floss described as PTFE, glide, or shred resistant is generally a PTFE monofilament.
Does waxed floss clean better than unwaxed floss?
There is no established cleaning advantage either way. Both remove plaque by the same mechanical action. Waxed floss slides more easily and resists shredding, suiting tight contacts. Unwaxed floss is thinner and can feel as though it grips more. Choose the one that fits your gaps and that you will use daily.
Should I stop using PTFE floss because of PFAS?
The sources behind this article do not say that. A 2019 peer reviewed study found that women who reported using a PTFE based glide floss had higher blood levels of one PFAS chemical, PFHxS, but it showed an association, not proof that floss caused it. The American Dental Association said the data were insufficient to support the conclusions drawn, and it continues to recommend daily cleaning between teeth. If you would rather avoid PTFE, nylon, silk, and plant based flosses clean just as well with good technique.
What is the healthiest floss material?
No material is ranked healthiest in itself. Daily cleaning between teeth, with good technique, is what protects gums and helps prevent decay there, and every common material can do that job. Fit, comfort, and any preference about synthetic fibers or fluoropolymers are the sensible deciding factors. Your dentist can advise on your teeth and dental work.
Are floss picks as good as string floss?
They use the same materials and can clean the same gaps, and they help many people reach back teeth. One short segment serves the whole mouth, so rinse the pick as you go and replace it when it frays. If a pick is what makes daily cleaning happen, it is a reasonable choice.
Why does my floss keep shredding?
Usually because a multifilament strand is catching on a tight contact, a rough filling edge, or a chipped area. Try waxed floss, a PTFE monofilament, which has no strands to split, or a wider tape. If it shreds on the same tooth every time, mention it at your next dental visit: a rough edge or tartar deposit may need professional attention.
Do children need to floss?
Yes, once they have two teeth that touch. MouthHealthy advises flossing from that point, with an adult doing it at first. Children usually have the hand skills to take over around age 10 or 11. Material matters less than supervision and habit.
Sources & references
- American Dental Association, MouthHealthy, Flossing. Floss once a day to remove food particles and plaque a toothbrush cannot reach; plaque bacteria, acids, and tartar formation; traditional floss described as a smooth strand of nylon or Teflon; dental picks, tiny brushes, pre threaded flossers, and water flossers as alternatives; ADA Seal of Acceptance products shown to be safe and effective; children to floss once two teeth touch, taking over around age 10 or 11; the five step flossing method including about 18 inches of floss, a gentle rubbing motion, never snapping into the gums, and a C shape at the gum line. https://www.mouthhealthy.org/all-topics-a-z/flossing
- NHS, How to keep your teeth clean. Brush twice a day for about two minutes with fluoride toothpaste; plaque as a film of bacteria contributing to gum disease and tooth decay; regular flossing may reduce gum disease, tooth decay, and bad breath by removing plaque along the gum line; best to floss before brushing; 30 to 45 centimeters of floss or tape with 3 to 4 centimeters taut, slipped between teeth and gums and curved into a C shape; interdental brushes or single tufted brushes instead of flossing where there are gaps, fitted snugly; wooden toothpicks not advised. https://www.nhs.uk/live-well/healthy-teeth-and-gums/how-to-keep-your-teeth-clean/
- American Dental Association, ADA Statement on Study Involving Dental Floss, January 2019, ADA Science Institute. The ADA found the data in the 2019 floss study insufficient to support the conclusions presented; the study was a single small retrospective study of 178 women using self reported product use; fluorine was measured as a marker of PTFE while the blood finding concerned PFHxS, so a PTFE marker in floss does not establish floss as the PFHxS source; no FDA restrictions on dental floss use had been issued; the ADA continued to encourage daily cleaning between teeth. Reproduced at https://www.oralhealthgroup.com/news/ada-statement-on-study-involving-dental-floss-1003939091/
- Boronow, K. E., Brody, J. G., Schaider, L. A., Peaslee, G. F., Havas, L., and Cohn, B. A., Serum concentrations of PFASs and exposure-related behaviors in African American and non-Hispanic white women, Journal of Exposure Science and Environmental Epidemiology, 2019, 29, 206 to 217. Measured 11 PFAS in blood from 178 middle aged women; reported use of a PTFE based glide floss was associated with higher PFHxS levels; product testing of 18 flosses using particle induced gamma ray emission spectroscopy found detectable fluorine in glide and competitor flosses, implicating exposure from PTFE based dental floss as an association for the first time.
- American Dental Association, ADA News, Colorado introduces bill tackling forever chemicals. The ADA is continuing to monitor the issue of polytetrafluoroethylene in oral care products; to date the ADA sees no cause for concern based on the current evidence and maintains its recommendation that people clean between their teeth daily with floss or another interdental cleaner. http://adanews.ada.org/huddles/colorado-introduces-bill-tackling-forever-chemicals/
- Worthington, H. V., and colleagues, Home use of interdental cleaning devices, in addition to toothbrushing, for preventing and controlling periodontal diseases and dental caries, Cochrane Database of Systematic Reviews, 2019, CD012018. Review of 35 studies: floss or interdental brushes plus toothbrushing may reduce gingivitis or plaque, or both, more than toothbrushing alone; interdental brushes may be better than floss for gingivitis at one and three months; evidence low to very low certainty, mostly short term. https://pmc.ncbi.nlm.nih.gov/articles/PMC6953268/
- Performance Evaluation of Dental Flosses Pre- and Post-Utilization, Materials, 2022, 15(4), 1522. Flosses categorized as monofilament and multifilament, waxed and unwaxed, synthetic and natural; monofilaments contain one strand and multifilaments several strands twisted together; natural floss is silk and synthetic floss is nylon or PTFE; nylon has very low friction and relative durability, PTFE is slightly more tolerant to elongation; wax coating is usually synthetic, with natural options using candelilla wax; dental tapes are flattened with a rectangular cross section. https://pmc.ncbi.nlm.nih.gov/articles/PMC8879268/
