How to Floss

Why Brushing Alone Misses the Gaps

A toothbrush cleans the front, back and biting surfaces well. Its bristles, however, barely reach the narrow sides where teeth touch. Plaque left there irritates the gum and feeds decay. Floss or an interdental brush reaches those surfaces, so the two habits work as a pair. That is why learning how to floss pays off.

What plaque does between your teeth

Plaque is a sticky film of bacteria that forms soon after eating. Left alone, it can make gums red and swollen within days. Later it hardens into tartar, which only a professional scale and polish can remove. Trapped food and plaque feed the bacteria behind bad breath too.

How to Floss Without Hurting Your Gums

Break off about 18 inches (45 cm) of floss and wind it around your middle fingers. Next, ease it between two teeth with a gentle back-and-forth motion. At the gumline, curve it into a C around one tooth and rub gently. In short, that is how to floss without snapping into the gum.

1. Wind most of the floss around one middle finger.
2. Wrap the rest around the other middle finger.
3. Pinch it between thumbs and index fingers, leaving a short taut section.
4. Ease it between two teeth; never snap it down.
5. Curve it into a C and slip it just under the gumline.
6. Rub up and down a few times, then do the neighbouring tooth.
7. Use a clean section for each gap, including behind the back molars.

Finding the right pressure

Stop as soon as you feel gentle resistance below the gum edge. Forcing it deeper can cut the gum, but staying too shallow leaves plaque behind. Flossing should never feel sharp, so ease off if it does.

Getting comfortable at the back

Open your mouth only halfway; a relaxed cheek makes back teeth easier to reach. A mirror helps while you learn how to floss during the first few weeks.

Floss, Tape, Picks or Interdental Brushes?

The right tool depends on the size of the gaps between your teeth. For example, thin waxed floss slides through tight contacts, while wider tape suits larger spaces. Where gaps are wide or gums have receded, a snug interdental brush usually cleans better. Choosing well is half of knowing how to floss.

Floss picks: convenient, with one catch

Picks work with one hand, which helps people with limited dexterity. Yet a short, rigid strand cannot hug the tooth like loose floss. So angle the pick against each side of the gap and rub a few times. Throw it away after one use.

Interdental space

The gap between two neighbouring teeth, where a toothbrush cleans least well.

Contact point

The spot where two teeth touch; floss meets slight resistance as it passes through.

Plaque

A soft, sticky layer of bacteria on the teeth that hardens into tartar if left alone.

Gingivitis

Gum inflammation, usually showing as redness, swelling and bleeding when you clean.

Floss threader

A flexible plastic loop that feeds floss under a brace wire or a bridge.

Is Flossing Actually Worth It?

Yes, for most people, although the research is less dramatic than many assume. A 2019 Cochrane review pooled 35 trials with 3,929 adults. Flossing alongside brushing may reduce gum inflammation in the short and medium term. The certainty of that evidence, however, is low.

Floss or interdental brushes, used with a toothbrush, may reduce gum inflammation and plaque more than brushing alone. Interdental brushes may outperform floss. Most of this evidence is of low or very low certainty.

Summary of Worthington HV et al. Cochrane Database of Systematic Reviews, 2019.

What the review could not show

No trial measured decay between teeth, so the effect on cavities is unknown. Most studies were short, and many participants started with healthy gums. Even so, none reported serious harm. On balance, a few minutes a day still makes learning how to floss worthwhile.

Cleaning Around Braces, Bridges and Implants

Brackets, bridges and implant crowns create places where plaque hides and ordinary floss cannot pass. A threader, or spongy floss with a stiff end, feeds the strand underneath. Interdental brushes usually work faster around brackets. Learning how to floss around dental work takes some practice at first.

How to floss with braces

Thread the stiff end under the main wire between two brackets. Then pull a length of floss through and clean both tooth sides with the C motion. After that, small interdental brushes can tidy around each bracket.

Bridges and implants

So how do you floss under a fixed bridge? Push the threader beneath the false tooth and wipe its underside with the spongy section. Around implants, plaque can inflame the gum just as it does around natural teeth. For that reason, your dentist may suggest an interdental brush with a plastic-coated wire.

Why Do My Gums Bleed When I Floss?

Light bleeding in the first days is common. It usually means plaque has already inflamed the gum. So keep going gently every day. As plaque clears, the inflammation settles and bleeding typically eases within a few days. Many people searching how to use dental floss quit too early.

When bleeding needs a dentist

Book an examination if bleeding continues despite gentle daily cleaning. Swelling, pus, a bad taste or loose teeth also need checking, because they can signal gum disease. Blood thinners make gums bleed more easily, so mention them. Our page on bleeding gums explains the common causes.

Building a Daily Flossing Habit

Clean between your teeth once a day, as the American Dental Association advises. The ADA says the order does not matter. By contrast, the NHS says it is best to floss before brushing. Evening suits many people, because saliva flow drops overnight. Still, once you know how to floss, the right time is simply the one you keep.

Children and flossing

Start cleaning between a child’s teeth once two teeth touch. Parents usually do it at first, and floss picks help. Children then take over as their hand control improves. Our guide to preventing tooth decay in children covers the other steps.

Signs your technique needs work

The usual errors are snapping floss into the gum and reusing a dirty section. Floss that shreds in one gap may point to a rough filling, tartar or decay. Mention it at your next visit, since a filling sometimes just needs smoothing.

Later in life

As gums recede with age, gaps widen and interdental brushes become more practical. Floss holders help when stiff joints make fine movements difficult. Our article on dental health after 60 has more tips.