Water Flosser vs. String Floss: Which Is Worth Your Money?

Water flossers shoot a thin stream of pulsing water between your teeth and along the gumline. They’re sold as an easier, gentler way to floss, at a price many times that of a spool of floss. Before you buy, here is how they compare with floss and the tiny interdental brushes on the same shelf.

What the research compared

A Cochrane¹ review pooled 35 trials with 3,929 adults. It looked at cleaning between the teeth in addition to brushing, compared with brushing alone.¹

Tool, added to brushing	Gum inflammation (gingivitis)	Plaque	Certainty of evidence
String floss	May reduce it at 1, 3 and 6 months	Results inconsistent	Low to very low
Interdental brushes	May reduce it at 1 month	May reduce plaque	Low to very low
Water flosser	May reduce it at 1 month, but not at 3 or 6 months	No reduction shown at 1, 3 or 6 months	Low to very low

All three comparisons are from the same review.¹ “Low certainty” means further research could change the picture. The review also found low-certainty evidence that interdental brushes may beat floss for gum inflammation. No trials measured cavities between the teeth.¹

The American Dental Association (ADA)² sums up the evidence for oral irrigators as limited and inconsistent.²

What the ADA advises

The ADA recommends brushing twice a day and cleaning between your teeth once a day with floss or another interdental cleaner. It says what matters most is how and when you use floss, not the type. Waxed and unwaxed floss work about the same.²

The ADA also notes that interdental brushes suit people with wider spaces between teeth or gum disease, while floss suits tight spaces. Brushes made for implants have coated wire so they don’t scratch.²

When a water flosser may still make sense

• You won’t floss, but you will use a water flosser. A tool you use daily beats one in a drawer. Ask your hygienist whether it’s cleaning well enough for your gums.
• Your hands make floss hard. Arthritis or a weak grip can make wrapping floss around your fingers difficult. Floss holders and interdental brushes are other options to try first.
• You have bridges, implants or other dental work. Ask your dentist which tool fits around it best.

Before you buy

1. Ask at your next cleaning which tool suits the spaces between your teeth and the state of your gums.
2. Look for the ADA Seal. The ADA keeps a searchable list of powered interdental cleaners that have earned it.²
3. Count the running costs. Check the price of replacement tips, how often they need changing, and whether the unit needs batteries or charging.
4. Check counter space and noise. Countertop models need a sink-side outlet; cordless models hold less water.

Try: “I find floss hard to use. Would a water flosser, interdental brushes or a floss holder work best for my teeth and gums?”

Is It My Breath? includes a visit script. Use it to organize your questions about cleaning between teeth, gum bleeding and breath before your next dental visit.