By Susan Volk, RDH — Last updated August 20, 2026
Short answer: Flossing removes plaque from between teeth and just below the gumline — the two areas a toothbrush physically can’t reach. The most common mistake isn’t skipping it, it’s rushing it: snapping the floss straight down between teeth instead of curving it against each tooth surface and going slightly beneath the gum. Correct technique matters more than which type of floss you use.
Why Brushing Alone Isn’t Enough
A toothbrush cleans the flat surfaces of your teeth well, but it can’t reach the tight contact points between teeth, where plaque builds up just as readily. Left there, that plaque hardens into tartar and becomes a common starting point for both cavities between teeth and gum inflammation — which is why people who brush diligently but skip flossing can still develop gum disease and decay specifically in those spots.
The Technique That Actually Works
Use about 18 inches of floss, winding most of it around your middle fingers and leaving an inch or two of working length between your hands. Guide the floss between two teeth using a gentle back-and-forth motion rather than snapping it down — snapping can cut or bruise the gum tissue. Once it’s between the teeth, curve the floss into a “C” shape against one tooth and slide it up and down, going slightly beneath the gumline where plaque tends to hide. Then curve it against the neighboring tooth and repeat before moving to the next gap.
Each gap between teeth has two surfaces to clean — one on each tooth — and it’s easy to floss straight through without actually contacting either surface properly. That’s the single biggest technique gap between flossing that feels thorough and flossing that’s actually effective.
Alternatives to String Floss
If string floss is difficult to manage — due to dexterity, braces, or bridges — there are effective alternatives. Interdental brushes (small bristled picks) are often better than floss for larger gaps or around orthodontic hardware. Water flossers use a pressurized stream of water to dislodge plaque and food debris and are a solid option for people with limited dexterity or for cleaning around bridges and implants, though they work best alongside — not as a full replacement for — mechanical contact from floss or an interdental brush for tight spaces. Floss picks are better than nothing but tend to encourage the “snap through” mistake since the floss is held rigid rather than curved by hand.
When to Floss
Once a day is generally sufficient — what matters more than timing is consistency and technique. Flossing before brushing, rather than after, may slightly improve how much plaque the subsequent brushing removes, though the difference is modest; the more important habit is simply doing it daily, at whatever time you’ll actually stick with.
Frequently Asked Questions
My gums bleed when I floss. Should I stop?
No — bleeding when you floss is usually a sign of gum inflammation from plaque buildup in that area, not a sign that flossing is hurting you. It typically stops within a week or two of consistent daily flossing as the gum tissue heals. If bleeding continues past a couple of weeks or is heavy, that’s worth mentioning at your next dental visit.
Is a water flosser as effective as string floss?
Water flossers are effective at disrupting plaque and clearing debris, and research shows they can reduce gingivitis, but they don’t fully replace the mechanical scraping action of floss or an interdental brush against the tooth surface in tight contact points. Many hygienists recommend them as an addition for people with braces, bridges, or implants rather than a full swap.
Does the type of floss (waxed, unwaxed, flavored) matter?
Not much for effectiveness — it mostly comes down to comfort and preference. Waxed floss tends to slide more easily between tight teeth. What matters far more is the curving, gumline-reaching technique described above.