How to Floss Properly to Prevent Plaque and Gum Problems

Flossing has a poor reputation, partly deserved. Studies of floss as it is typically used show modest benefit, and some people give up on it entirely.

The underlying issue is usually technique. Floss used correctly disrupts biofilm below the gum margin on the surfaces a toothbrush cannot reach. Floss used as a food-removal tool — snapped down, pulled through, moved on — does very little.

Around 40 per cent of the total tooth surface lies between the teeth, in the contact areas that face the neighbouring tooth.

A toothbrush cannot reach these surfaces. The bristles pass over the outer and inner faces and skip across the contacts.

The consequences are predictable. Interproximal decay — cavities forming between teeth — is common precisely because of this, and it typically progresses unnoticed because it is not visible and often not painful until it is substantial. Our article on whether a dentist can find decay without X-rays explains why radiographs are needed to detect it.

Periodontal disease also starts interdentally, in the col area between teeth, which is the most vulnerable part of the gum.

So the space between your teeth is where both of the major dental diseases begin, and it is the space your toothbrush does not enter.

The mechanics that matter are these.

1. Use enough floss. Around 45cm, wound around the middle fingers of each hand, leaving a few centimetres to work with. Wind on a fresh section as you move around the mouth so you are not moving plaque from one space to the next.

2. Guide it through the contact gently. Use a sawing, back-and-forth motion to ease it past the tight point. Do not snap it straight down — that traumatises the gum tissue between the teeth, and repeated over months it causes damage.

3. This is the part most people miss: curve it into a C shape against one tooth. Wrap the floss around the side of the tooth so it hugs the curved surface.

4. Slide it gently below the gum margin. The sulcus is typically 1 to 3mm deep in health. Plaque accumulates there, and this is where gum disease begins. You should feel slight resistance, not pain.

5. Move it up and down against that tooth surface several times, scraping the biofilm off.

6. Then curve it the other way against the adjacent tooth and repeat. Each space has two surfaces and both need cleaning — a single pass through the contact cleans neither properly.

7. Work systematically around the whole mouth, including behind the very back teeth, which are routinely forgotten.

Once a day is sufficient. Doing it properly once beats doing it carelessly twice.

Our article on how to floss between teeth covers the practical steps, and our article on whether mouthwash can replace flossing addresses the common shortcut.

Sawing the floss between the teeth and pulling it straight out. This removes trapped food and nothing else.

Not going below the gum line. The area above the gum margin is not where periodontal disease starts.

Using too much force. Snapping through the contact cuts the papilla and can, over time, create a notch in the gum.

Using the same section throughout.

Stopping because the gums bleed. This is the most consequential error, and it is worth dwelling on.

Healthy gums do not bleed when cleaned properly. Bleeding indicates inflammation — the tissue is engorged, the capillaries are close to an ulcerated surface, and mechanical contact breaks them.

The instinct is to stop cleaning the area that bleeds. This allows more plaque to accumulate, worsening the inflammation.

In most cases of gingivitis, consistent daily interdental cleaning reduces bleeding substantially within one to two weeks. If bleeding persists beyond that, it warrants assessment, because it may indicate periodontitis rather than simple gingivitis.

Our article on why gums bleed when brushing and our article on the hidden danger of bleeding gums cover what bleeding indicates, and our article on managing bleeding gums covers what to do.

This is important and frequently under-communicated.

Where the spaces between the teeth are large enough to accommodate them, interdental brushes remove more plaque than floss and are easier to use correctly. Reviews of interdental cleaning support this consistently.

They are the preferred option where:

• There is gum recession, creating open spaces at the gum margin

• There has been periodontal treatment, after which spaces typically open up

• There are bridges, implants or orthodontic appliances

• Dexterity is limited, since they are considerably easier to handle

Sizing matters more than anything else. A brush too small for the space passes through without contacting the surfaces and achieves very little. A hygienist should size them for you, and different spaces in the same mouth commonly need different sizes.

Floss remains the appropriate tool where contacts are tight and no brush will pass.

In practice many people need both, in different parts of the mouth.

Our dental hygiene page explains what a hygiene appointment covers.

Floss picks and holders. Easier to handle, particularly for back teeth, but the fixed span makes it harder to curve the floss into a C shape. Better than not cleaning at all; less effective than floss used correctly.

Tape versus waxed versus unwaxed. Waxed slides through tight contacts more easily. Tape is broader and suits wider spaces. The difference is minor compared with technique.

Water flossers. Effective at reducing bleeding and useful around bridges, implants and orthodontic appliances where access is difficult. Evidence for plaque removal relative to floss and interdental brushes is more mixed — water disrupts loose debris well but does not scrape adherent biofilm as effectively as physical contact. Best regarded as an adjunct. Our article on water flossers for implants covers the options.

Mouthwash. It does not remove plaque mechanically. Our article on whether mouthwash helps covers what it does and does not do.

Within one to two weeks of consistent, correct daily cleaning, most people see bleeding reduce substantially.

Within a few weeks, gums that were puffy and red become firmer and paler.

Bad breath frequently improves, since interdental plaque is a major contributor. Our article on bad breath after brushing covers the causes.

Over years, the effect is on decay between the teeth and on attachment loss, neither of which you can observe directly — which is why it is easy to stop, and why professional monitoring matters.

How often should I floss?

Once a day is sufficient, provided it is done properly. Plaque takes around 24 hours to reorganise after disruption, so daily cleaning stays ahead of it.

Should I floss before or after brushing?

Either works. Some evidence suggests flossing first allows fluoride from toothpaste better access to the interdental surfaces. Consistency matters more than order.

My gums bleed when I floss. Should I stop?

No. Bleeding indicates inflammation from plaque, and stopping allows more plaque to accumulate. Continue gently and daily; bleeding usually reduces markedly within one to two weeks. If it persists, have it assessed.

Are interdental brushes better than floss?

Where the space accommodates them, yes — they remove more plaque and are easier to use correctly. Floss is appropriate where contacts are too tight for a brush to pass.

Can a water flosser replace flossing?

It is a useful adjunct, particularly around bridges, implants and braces, but it does not disrupt adherent biofilm as effectively as physical contact. Use it alongside rather than instead.

Does flossing create gaps between my teeth?

No. Spaces that appear after cleaning improves are usually the result of swollen gum tissue shrinking back to a healthy contour, revealing space that was already there. This is a sign of improvement, though it can be disconcerting.

Why does floss shred in one particular place?

That usually indicates a rough restoration margin, a fractured filling, decay or an overhang. It is worth having that area examined rather than working around it.

If you are not sure whether your technique is effective, ask at your next hygiene appointment. Disclosing solution stains retained plaque and shows exactly which surfaces you are missing, and the pattern is usually consistent and correctable in a few minutes of instruction.

If your gums bleed regularly despite cleaning, that warrants assessment rather than more effort.

You can contact our team to arrange an appointment at our Wimpole Street practice. Our dental hygiene and gum disease treatment pages explain what is involved.

This article provides general information and does not constitute individual dental advice. Interdental cleaning requirements vary between individuals depending on gum condition, spacing, restorations and dexterity, and should be tailored following clinical assessment. Persistent bleeding, pain or swelling of the gums should be examined by a dental professional. Wimpole Dental is regulated by the Care Quality Commission, and our clinicians are registered with the General Dental Council.

Next review due: 2 September 2027