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Floss, Interdental Brush or Water Flosser?

Answer six quick questions about your teeth, gums and dental work. Get a ranked shortlist of floss, floss picks, interdental brushes, water flossers and more, with the evidence behind each pick and how to use it.

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Your shortlist

    Other options

      The order uses our own simple weights: each tool starts from the overall evidence, and each answer moves it up or down for a reason shown on its card.

      How often

        If your gums bleed when you start

          This is general information, not a diagnosis.

          How to use your shortlist

          What the evidence says overall

          Each tool used on top of brushing, compared with brushing alone. Mostly from the 2019 Cochrane review; the source is shown in each row. Your shortlist is highlighted.

          Effect of each interdental cleaner on gum inflammation and plaque, and how certain the evidence is
          ToolGum inflammationPlaqueCertainty

            Floss, interdental brush or water flosser: which is best?

            Where it fits, an interdental brush has the best support. Floss is the tool for tight spaces, and a water flosser is a useful extra around braces, bridges and implants.

            A 2019 Cochrane review of 35 trials (3,929 adults) compared each tool, used on top of brushing, with brushing alone:

            • Interdental brushes may reduce plaque, and may reduce gum inflammation more than floss at 1 and 3 months.
            • Floss may reduce gum inflammation over 1 to 6 months, but its effect on plaque was mixed.
            • Water flossers may calm gum inflammation at 1 month, but not at 3 or 6 months, and they didn't reduce plaque.
            • Wooden sticks and rubber picks had one or two tiny trials each, with small, uncertain effects.

            The review rated all of this low or very low certainty. European gum specialists still reached a clear practical answer in a 2015 consensus report: interdental brushes are the device of choice, and floss is for healthy spots where a brush won't pass without force. The ADA agrees that floss may suit tight spaces, while brushes suit gum disease and wider spaces.

            Floss picks hold the same floss on a handle. Small studies found them about as good as flossing by hand, and one found they helped people keep the habit (Ng and Lim review, 2019). Rubber picks did about as well as wire brushes in small trials. Wooden sticks are triangular, so they only suit open spaces.

            Is flossing really necessary?

            Cleaning between your teeth once a day is recommended. Floss is just one way to do it. The ADA recommends brushing twice a day and cleaning between your teeth once a day with floss or another interdental cleaner.

            The catch: the evidence is weaker than most people assume. The Cochrane authors rated it low to very low certainty and said the effects may be too small to matter clinically. Trials measured results at 1 to 6 months, and most didn't look at periodontitis. No trial measured tooth decay between the teeth.

            Weak evidence is not proof of no benefit. A meta-analysis cited by the ADA found that regular flossing by a professional, 5 days a week, cut cavities between teeth. Professional flossing every 3 months, and flossing on your own, didn't show that effect. Gum specialists recommend once-daily cleaning between the teeth for anyone with gum inflammation.

            How to use floss picks, interdental brushes and a water flosser

            The tool gives step-by-step instructions for your shortlist. In brief:

            • Floss and floss picks: guide the floss in gently, never snapping it into the gum. Curve it against one tooth at the gum line, rub up and down, then do its neighbor (ADA).
            • Interdental brushes: insert gently, close to the gum, and move back and forth 2 or 3 times. Never force it. Bend small brushes slightly for the back teeth (Oral Health Foundation).
            • Water flosser: start on the lowest pressure, lean over the sink, and aim at the gum line and between the teeth for about 2 seconds per tooth. These steps come from a maker's guide, so check your manual.
            • Before or after brushing? The ADA says it doesn't matter. The NHS says before. Pick a time you'll stick to.

            It shouldn't hurt. Inflamed gums may be sore and bleed for the first few days, so keep going gently. If it doesn't improve within a few days, see your dentist (Oral Health Foundation).

            What size interdental brush do I need?

            The one that slides in snugly without force, and often 2 or 3 different sizes around your mouth. Start with the smallest brush and go up until the bristles touch both teeth and the gum (Oral Health Foundation).

            The ISO 16409 standard sizes brushes by the smallest hole they pass through without bending (the passage hole diameter). A 2020 study of 2,320 brushes from 24 makers found:

            • Each maker uses its own color code, so colors don't match between brands.
            • Only a third of makers printed the ISO size, and a quarter printed the hole size.
            • Brushes on sale ranged from 0.6 to 5.2 mm, and 9 in 10 were 2.0 mm or less.

            So there's no reliable size chart, and we don't print one. Look for the ISO size or hole size on the pack, and note the brand and size that fit, because a color won't carry over to another brand. Better still, ask your dentist or hygienist to size you.

            Cleaning around braces, bridges and implants

            Braces. Clean between your teeth at least once a day. The AAO says an interdental brush helps clean around brackets and under wires, and that you may need a floss threader or orthodontic flosser for floss. A 2025 review found water flossers gave slight short-term improvements in gum bleeding for people with braces, in a few small trials. Pair this with daily brushing, timed by the Two-Minute Brushing Timer, and check foods with the Braces Food Checker.

            Permanent retainer. The wire traps plaque. The AAO suggests floss threaders, interdental brushes or a water flosser to clean around it every day.

            Bridges. Clean under the false tooth every day with a floss threader or interdental brushes (Cleveland Clinic). The ADA says a water flosser may help people with bridges reach every nook.

            Implants. Use brushes with coated wire so they don't scratch the implant (ADA). A 2019 review prefers brushes and water flossers over floss, which can fray on rough, exposed implant surfaces. The 2023 European implant guideline says home care should suit the design of your implant work, and that a water flosser may be added to professional cleaning for inflamed gums around implants (low-quality evidence).

            How this tool works

            1. Starting points from the overall evidence. Interdental brushes start at 3 points, floss and floss picks at 2, and water flossers, rubber picks and wooden sticks at 1, reflecting the Cochrane review and the European consensus.
            2. Each answer adds or takes away points, only where a source backs it. Tight spaces add 3 to floss and take 2 from brushes, because a brush must never be forced. Treated gum disease adds 3 to brushes (European guideline, 2020). Braces add 3 to brushes and water flossers (AAO, 2025 review). Trouble using your hands adds 3 to floss picks (National Institute on Aging).
            3. Ties keep the evidence order: brushes, floss, picks, water flosser, rubber picks, wooden sticks.
            4. The top three become your shortlist, each with its reasons, evidence and any "watch out" points, plus how-to steps, brush sizing when brushes or rubber picks make the list, and a threader guide for braces, bridges and fixed retainers.

            Limits. The points are our own editorial weights, not published values. Most trials were small, short and in adults, and none measured tooth decay. There's no question about time because no source compares how long each tool takes. Your dentist or hygienist can see your actual gaps, and this tool can't. It gives general information, not a diagnosis.

            Frequently asked questions

            Is flossing really necessary?
            Cleaning between your teeth is, but it doesn't have to be floss. The ADA recommends cleaning between teeth once a day with floss or another interdental cleaner. A 2019 Cochrane review found that floss or interdental brushes on top of brushing may reduce gum inflammation, but the evidence is low certainty and no trial measured tooth decay.
            Are interdental brushes better than floss?
            Where they fit, they may be. The 2019 Cochrane review found brushes may reduce gum inflammation more than floss at 1 and 3 months (low-certainty evidence), and European gum specialists call them the device of choice. Floss is still the tool for spaces too tight for a brush.
            Can a water flosser replace flossing?
            Sources disagree. The ADA counts water flossers as interdental cleaners, and they may calm gum inflammation for the first month. But in the Cochrane review they didn't reduce plaque, and one maker says they shouldn't replace floss or brushes. The ADA says people with braces, bridges and other dental work may find them helpful.
            What size interdental brush do I need?
            Start with the smallest and go up until the bristles touch both teeth and the gum without forcing. Many people need 2 or 3 sizes. A standard (ISO 16409) measures brush size, but colors differ between brands and not every pack prints the size. Look for an ISO size or hole size on the pack, or ask your dentist or hygienist to size you.
            Should I floss before or after brushing?
            Either is fine. The ADA says it doesn't matter when, as long as you're thorough. The NHS says it's best to floss before brushing. Pick a time you can stick to every day.
            Why do my gums bleed when I floss?
            Bleeding is often a sign of inflamed gums, and it can happen when you first start. Keep cleaning gently. If it doesn't improve within a few days, gets worse or is heavy, see your dentist. Get an urgent appointment for very sore, swollen gums or loose teeth (NHS).

            Sources

            1. Worthington HV, MacDonald L, Poklepovic Pericic T, Sambunjak D, Johnson TM, Imai P, Clarkson JE. Cochrane Database of Systematic Reviews 2019;(4):CD012018. Home use of interdental cleaning devices, in addition to toothbrushing, for preventing and controlling periodontal diseases and dental caries. 2019. Accessed October 26, 2026.
            2. Chapple ILC, Van der Weijden F, Doerfer C, et al. Journal of Clinical Periodontology 2015;42(Suppl 16):S71–S76. Primary prevention of periodontitis: managing gingivitis (11th European Workshop on Periodontology consensus). 2015. Accessed October 26, 2026.
            3. Sanz M, Herrera D, Kebschull M, et al. Journal of Clinical Periodontology 2020;47(Suppl 22):4–60. Treatment of stage I–III periodontitis—The EFP S3 level clinical practice guideline. 2020. Accessed October 26, 2026.
            4. Herrera D, Berglundh T, Schwarz F, et al. Journal of Clinical Periodontology 2023;50(Suppl 26):4–76. Prevention and treatment of peri-implant diseases—The EFP S3 level clinical practice guideline. 2023. Accessed October 26, 2026.
            5. Ng E, Lim LP. Dentistry Journal 2019;7(2):56 (narrative review). An Overview of Different Interdental Cleaning Aids and Their Effectiveness. 2019. Accessed October 26, 2026.
            6. Badahdah A, Hariri MA, Aljohani MS, Alshehri LS, Natto ZS. Healthcare 2025;13(4):396. Alleviation of Plaque and Gingivitis with Dental Water Jet in Regular and Orthodontic Patients: A Systematic Review and Meta-Analysis. 2025. Accessed October 26, 2026.
            7. Sekundo C, Staehle HJ. Oral Health & Preventive Dentistry 2020;18(2). Mapping the Product Range of Interdental Brushes: Sizes, Shapes, and Forces. 2020. Cited for ISO 16409:2016 sizing (passage hole diameter) and supplier-specific color codes. Accessed October 26, 2026.
            8. American Dental Association. Dental Floss/Interdental Cleaners (Oral Health Topics). updated August 2026. Accessed October 26, 2026.
            9. American Dental Association (MouthHealthy). Flossing. Accessed October 26, 2026.
            10. NHS. How to keep your teeth clean. reviewed 30 June 2025. Accessed October 26, 2026.
            11. NHS. Gum disease. reviewed 20 April 2026. Accessed October 26, 2026.
            12. Oral Health Foundation. Cleaning between teeth: the secret behind a truly healthy smile. updated 28 January 2026. Written jointly with an interdental brush maker (TePe). Accessed October 26, 2026.
            13. American Association of Orthodontists. Swollen or Bleeding Gums with Braces: Causes and What to Do. 2026. Accessed October 26, 2026.
            14. American Association of Orthodontists. Oral Hygiene Tips During Orthodontic Treatment. 2025. Accessed October 26, 2026.
            15. American Association of Orthodontists. The Dos and Don'ts of Cleaning Your Retainer. updated April 2026. Accessed October 26, 2026.
            16. Illinois Department of Public Health. Oral Care for the Orthodontic Patient. Accessed October 26, 2026.
            17. Cleveland Clinic. Dental Bridges: Types & Who Needs Them. last updated May 24, 2023. Accessed October 26, 2026.
            18. National Institute on Aging (NIH). Taking Care of Your Teeth and Mouth. content reviewed August 8, 2024. Accessed October 26, 2026.
            19. Oral-B (Procter & Gamble). How to Use Water Flossers. updated June 2025. Manufacturer page, used for the operating steps and to show a maker's view. Accessed October 26, 2026.
            20. dentalcare.com (Procter & Gamble continuing education). Toothpicks/Interdental Stimulators, in A String around Your Finger: Do We Really Need to Floss?. Run by a toothpaste and floss maker (Procter & Gamble). Accessed October 26, 2026.

            Last reviewed by the Dental Health Time editorial team, against the sources above. How we review.

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