How to Floss Correctly: Technique, Frequency & Tools

Why does flossing matter for oral health?

Brushing cleans the visible surfaces of your teeth — front, back, and top — but the spaces between teeth and the area just below the gumline account for roughly 35% of each tooth's surface. Plaque that accumulates in these areas cannot be reached by a toothbrush bristle. Left undisturbed, plaque hardens into calculus (tartar) within a day or two, which can only be removed by a dental professional. Daily interdental cleaning disrupts this biofilm before it calcifies, reducing the risk of cavities between teeth and gum inflammation 1Ref 1American Dental Association (2024).Floss/Interdental Cleaners.ADA recommendation for once-daily interdental cleaning, evidence review on flossing and gingivitis reduction, guidance on tool selection including water flossers and interdental brushes2Ref 2Slayton RL, Urquhart O, Araujo MWB, et al. (2018).Evidence-based clinical practice guideline on nonrestorative treatments for carious lesions: A report from the American Dental Association.Plaque removal through brushing and interdental cleaning is foundational to preventing carious lesions.

The American Dental Association recommends brushing twice daily and using an interdental cleaner once per day, noting that floss and other interdental cleaners help remove plaque and debris from areas a toothbrush cannot reach 1Ref 1American Dental Association (2024).Floss/Interdental Cleaners.ADA recommendation for once-daily interdental cleaning, evidence review on flossing and gingivitis reduction, guidance on tool selection including water flossers and interdental brushes.

Step-by-step: the correct flossing technique

1. Cut a length of 18 inches. This gives you enough clean floss to use a fresh section for each tooth space. 2. Wind most of it around one middle finger, the rest around the other. Leave about an inch of working floss between the two fingers. 3. Slide gently between teeth using a back-and-forth sawing motion — do not snap or force it, as this can cut the gum. 4. Curve into a C-shape around the tooth. Hug the floss against the side of one tooth and slide it gently below the gumline until you feel light resistance. 5. Scrape upward away from the gum with gentle pressure. Repeat on the adjacent tooth in the same space. 6. Move to a fresh section of floss for each new tooth space. 7. Floss behind the last molars — the back surfaces are often missed but are a common site for gum disease.

If your gums bleed when you first start flossing regularly, that is usually a sign of existing inflammation, not evidence that flossing is harmful. Bleeding typically decreases within one to two weeks of daily flossing as the gum tissue becomes healthier.

Does it matter when in the day you floss?

Flossing before bedtime is commonly recommended because it removes food and plaque that would otherwise sit against teeth and gums overnight, when saliva flow decreases. That said, flossing at any consistent time of day is far more important than the specific timing 1Ref 1American Dental Association (2024).Floss/Interdental Cleaners.ADA recommendation for once-daily interdental cleaning, evidence review on flossing and gingivitis reduction, guidance on tool selection including water flossers and interdental brushes. If you find it easier to floss in the morning or after lunch and it means you do it every day, that is better than a "correct" time you skip regularly.

Water flosser vs. string floss: which is better?

Water flossers (oral irrigators) direct a pulsing stream of water between teeth and along the gumline. A 2023 systematic review found that the majority of studies favored water flossers over dental floss for plaque reduction, and that water flossers are particularly beneficial for people with limited manual dexterity, orthodontic treatment, or dental prostheses 3Ref 3Mohapatra S, Rajpurohit L, Mohandas R, Patil S (2023).Comparing the effectiveness of water flosser and dental floss in plaque reduction among adults: A systematic review.Systematic review finding water flossers favored over dental floss for plaque reduction in the majority of studies; particularly effective for patients with limited dexterity, orthodontic appliances, or dental prostheses.

For standard plaque removal, the ADA recommends continuing to use string floss as the primary interdental tool because the mechanical scraping action is effective at disrupting biofilm — and accepts water flossers as an effective alternative, particularly for those who struggle with traditional flossing 1Ref 1American Dental Association (2024).Floss/Interdental Cleaners.ADA recommendation for once-daily interdental cleaning, evidence review on flossing and gingivitis reduction, guidance on tool selection including water flossers and interdental brushes. A water flosser used in addition to — not instead of — string floss may provide added benefit. If you will only use one tool, use whichever one you will actually do every day.

What about floss picks, interdental brushes, and tape?

• Floss picks are convenient and easier to use in the back of the mouth than string floss, but you reuse the same section of floss for every tooth space — less hygienic than traditional technique.
• Interdental brushes (small conical or cylindrical brushes) work well for larger spaces between teeth, particularly for people with periodontitis who have developed some gum recession. Your dentist can advise on the right size.
• Dental tape is a flat, wider version of standard floss — sometimes easier for people with tight tooth contacts and less likely to shred.

The ADA recommends that the best tool is the one you use consistently and correctly 1Ref 1American Dental Association (2024).Floss/Interdental Cleaners.ADA recommendation for once-daily interdental cleaning, evidence review on flossing and gingivitis reduction, guidance on tool selection including water flossers and interdental brushes.