Water flosser vs string floss: which cleans better?

Why cleaning between teeth matters

A toothbrush can’t reach the tight spaces between teeth. Plaque that stays there can inflame the gums and lead to cavities between teeth. The ADA calls cleaning between your teeth an important part of your daily routine, and recommends doing it once a day.

If one spot keeps trapping food and aching, see gum pain around one tooth. Cleaning between teeth helps prevent that; it won’t treat a gum infection that’s already there.

What the research says

The best summary is a 2019 Cochrane review of 35 trials with nearly 4,000 adults. It looked at floss, interdental brushes, water flossers (called oral irrigators) and other tools, each added to regular brushing.

• Floss plus brushing may reduce gum inflammation (gingivitis) more than brushing alone. Results for plaque were mixed.
• Water flossers plus brushing may reduce gingivitis at one month, but the evidence was very low certainty, and the benefit didn’t show up in longer trials or for plaque.
• Water flosser vs floss, head to head: water flossers may reduce gingivitis at one month compared with floss (low to very low certainty). There was no clear difference for plaque.
• Interdental brushes (tiny brushes that fit between teeth) may reduce gingivitis more than floss at one and three months.

The reviewers rated the evidence low to very low certainty. They noted the differences may be too small to matter much, and no trial measured cavities between teeth. The ADA summarizes the evidence for water flossers as limited and inconsistent.

The honest takeaway: no tool has proven itself clearly better. Cleaning between your teeth every day matters more than which tool you use.

Who does better with which

String floss suits most people

Floss is cheap, needs no outlet and fits in a pocket. If you already floss daily and your checkups go well, there’s no strong reason to switch.

Not everyone agrees a water flosser can stand in for floss. A periodontist (gum specialist) interviewed by Cleveland Clinic calls it an add-on to string floss, not a substitute, because floss reaches below the gumline where water can’t always get to.

A water flosser helps some people more

A water flosser is a handheld device that sprays water in steady pulses. The ADA says it can help people who:

• Have trouble flossing by hand, such as from stiff or painful hands.
• Wear braces.
• Have a fixed bridge.

Cleveland Clinic adds people with dental implants or a lot of gaps between teeth, and says it may help sensitive gums. For implants, the ADA notes that interdental brushes made for implants have a coated wire so they don’t scratch.

The trade-offs: a water flosser costs more up front, needs refilling and often an outlet, and can be messy until you get the hang of it.

Other options

Floss picks, pre-threaded flossers and interdental brushes are all fine. The ADA’s point is to find one you’ll use.

How to use each one

String floss

1. Break off a long piece, about 18 inches, so you can use a clean section for each space.
2. Guide it between two teeth with a gentle rubbing motion. Never snap it into the gum.
3. At the gumline, curve it into a C shape against one tooth and slide it gently into the space between the gum and tooth.
4. Rub the side of the tooth with an up-and-down motion, then do the same on the neighboring tooth.
5. Move to a clean section of floss for each space.

It doesn’t matter whether you floss before or after brushing. What counts is doing it.

Water flosser

1. Fill the reservoir with warm water and choose a pressure setting.
2. Lean over the sink.
3. Aim the tip between your teeth and along the gumline, moving from tooth to tooth.

Follow the maker’s directions for your model.

What the ADA Seal means

For floss and other between-teeth cleaners, the ADA Seal means the maker showed that using it along with brushing reduces plaque and gingivitis better than brushing alone. For water flossers, the ADA says Seal products were tested to be safe and effective at removing plaque. Check for the Seal on the box or on the ADA’s product list before you buy.

What it costs to keep going

• String floss is the cheapest option. A specialty floss such as Cocofloss costs more; it’s worth it only if you’ll actually use it every day.
• A water flosser is a one-time cost for the unit, plus replacement tips over time. Check the maker’s guidance on how often to replace them.
• Checkups catch gum problems and cavities between teeth early, when they’re simpler to fix. If cost is keeping you away, see dental savings plans explained.

How to make it stick

• Pick one time of day and tie it to brushing, before or after.
• Keep the floss or flosser where you’ll see it.
• Brush twice a day with a fluoride toothpaste for two minutes. See the best electric toothbrush if a timer and pressure sensor would help.
• See a dentist for regular checkups. If your gums bleed, swell or ache around one tooth, mention it.