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This article is general information about oral-care tools, not dental or medical advice. Everyone’s mouth is different — for guidance on the best cleaning method for your teeth, gums, or dental work, see a dentist or other qualified dental professional.
Updated August 2026: restructured this comparison around the questions people search, added a claims-versus-research table sourced to the 2019 Cochrane review, the ADA, and makers’ own published claims, noted that Philips lists its Sonicare AirFloss line as discontinued, and added FAQ schema.
Nearly half of American adults — 42% of those aged 30 and older — have some form of periodontitis, per the CDC’s gum disease fast facts, yet a CDC-published analysis of national survey data from 2011–2014 found that only 31.6% of adults flossed daily. That gap is why the water flosser vs string floss question matters more than most gadget debates: the tool you will genuinely use every day beats the tool with the best ad.
The short version: no interdental method cleanly outranks the rest in published periodontal research — Cochrane’s 2019 review found only low- to very-low-certainty evidence for every tool it examined. String floss and interdental brushes have the broadest study base, water flossers earn their place for braces, bridges, and people who skip string floss, and the honest tiebreaker is whichever tool you will use daily.
Do periodontal studies crown a single best flossing method?
No — and knowing that up front will save you money and second-guessing. The most comprehensive evidence available is the 2019 Cochrane review by Worthington and colleagues, which pooled 35 randomized trials of home interdental cleaning. Its overall verdict: using floss or interdental brushes in addition to toothbrushing “may reduce gingivitis or plaque, or both,” but the evidence was “low to very low-certainty, and the effect sizes observed may not be clinically important.”
Two precision points matter when reading any claim in this category. First, studies measure different things — gingivitis indices, bleeding sites, and plaque scores are separate outcomes, and a tool can move one without moving another. Second, most trials in this field are short, often four weeks to three months, so long-term differences between methods are largely unmeasured.
What does the research say about string floss?
String floss has evidence behind it, but weaker evidence than its reputation suggests. In the 2019 Cochrane review, eight trials covering 585 participants provided low-certainty evidence that flossing plus toothbrushing may reduce gingivitis compared with brushing alone, while results for plaque were inconsistent. That does not make flossing pointless — it makes the confident “gold standard” framing stronger than the data.
Floss keeps two practical advantages no study is needed to see: it costs almost nothing, and it goes anywhere. Its real-world weakness is adherence — the technique takes dexterity, and as the daily-flossing figure above shows, most adults do not keep it up.
Are water flossers better for gingivitis and bleeding?
Better in some short industry-funded trials, unproven as a clear winner in independent reviews — both halves of that sentence are true at once. On the encouraging side, the ADA’s consumer site MouthHealthy says water flossers carrying the ADA Seal of Acceptance have been tested to be “safe and effective at removing a sticky film called plaque” and “can also help reduce gingivitis,” and it names them “an option for people who have trouble flossing by hand” or who have braces or permanent bridges. On the cautious side, the 2019 Cochrane review found only very-low-certainty evidence that oral irrigators may reduce gingivitis at one month, and no demonstrated benefit for plaque.
Where water flossers clearly win is fit: they navigate orthodontic hardware, bridges, and implants that string snags on, and many people who dread string floss will happily use one — and daily use of a decent tool beats occasional use of a theoretically better one.
What do makers claim versus what studies report?
| Method | The marketing claim | What published research reports |
|---|---|---|
| Water flosser | Waterpik’s own professional research page: “up to 52% better at reducing gingivitis” and “up to 93% better in reducing bleeding” than string floss, citing Barnes 2005 (J Clin Dent) — a four-week, 105-subject, industry-connected study | 2019 Cochrane review: very-low-certainty evidence that oral irrigators may reduce gingivitis at one month; no demonstrated benefit for plaque |
| String floss | Widely framed as the gold standard for gum health | 2019 Cochrane review: low-certainty evidence from 8 trials (585 participants) that flossing plus brushing may reduce gingivitis; inconsistent plaque results; effect sizes “may not be clinically important” |
| Air floss | Philips’ US product page: removes “up to 99.9% of plaque from treated areas” and is “clinically proven as effective as floss for gum health” | Both claims are qualified to “treated areas” or gum health specifically — and the Sonicare AirFloss line is marked discontinued on Philips’ US product pages as of August 2026 |
| Interdental brushes | Rarely advertised at all | 2019 Cochrane review: “Interdental brushes may be more effective than floss,” on low- to very-low-certainty evidence — the closest the review comes to naming a leader |
Every figure in this table was checked against the named source in August 2026. The pattern to notice: maker claims tend to come from short single studies with the maker’s involvement, while independent pooled reviews consistently land on smaller, less certain differences.
What happened to air flossers?
The category’s flagship quietly left the market: Philips’ US product pages now list Sonicare AirFloss models as discontinued. The device — rapid bursts of air and micro-droplets, aimed at people who wanted less mess than a water jet — still surfaces through third-party sellers, but a discontinued platform means dwindling nozzles and support. If the low-mess pitch is what drew you to air floss, a cordless water flosser is the closest currently supported equivalent; if the speed pitch drew you, interdental brushes are quicker still.
So which method should you choose?
Choose by fit, because the effectiveness gap is too uncertain to pay for. With braces, bridges, or implants, a water flosser is the tool the ADA specifically points to for hardware. On a tight budget with decent dexterity, string floss remains the cheapest evidence-backed option. If string floss defeats you and gadgets gather dust, interdental brushes are cheap, fast, and hold the strongest relative showing in the Cochrane data — where they fit your gaps. And whatever you pick, once a day, per the ADA, is the target that matters.
How we compared
We did not run clinical comparisons ourselves and this page reports no hands-on results. We compared the three method categories against published evidence — the 2019 Cochrane review of home interdental cleaning, the ADA’s consumer guidance, CDC prevalence data, and makers’ own published claims — verifying each cited figure against its named source in August 2026. Where evidence is weak or industry-funded, we say so rather than round up. No prices appear in this guide because ongoing costs vary too much by model and refill habits to state honestly in one figure. Read more about how we work on our editorial standards page, and bring product questions to your dentist, who knows your mouth.
Frequently asked questions
How often should you clean between your teeth?
Once a day, according to the ADA’s consumer guidance, which calls cleaning between your teeth once a day an important part of your dental hygiene routine. Time of day matters less than consistency.
Can a water flosser replace brushing?
No. Interdental cleaning of any kind supplements brushing rather than replacing it — the two reach different surfaces, and the research on water flossers measures them as an addition to toothbrushing, not a substitute.
What does low-certainty evidence mean for choosing a flosser?
It means the measured differences between methods are too uncertain to justify paying a premium on effectiveness grounds alone. Pick by fit: cost, dexterity, dental work, and which tool you will use every day.
Which tool do dentists point to for braces?
Water flossers are the option the ADA specifically names for people with braces or fixed bridges, since the stream reaches around hardware that string floss snags on. Your own dentist or orthodontist can confirm what suits your treatment.
Bottom line
Periodontal research supports cleaning between your teeth daily far more strongly than it supports any one tool for doing it. Let your dental work, budget, and honesty about your own habits pick the method, and let your dentist confirm it. Exploring more of your daily routine? Our Beauty & Grooming section has plenty more, including our comparison of at-home hair removal methods and our guide to choosing a facial cleanser.
