Should I use floss or an interdental brush?

The choice depends on the width of the spaces between the teeth. Where the teeth are in tight contact, floss is appropriate. Where the spaces have widened because of gum recession, an interdental brush removes plaque more effectively, as floss cannot make full contact with the surface. The appropriate brush diameter varies with the space and is determined by the dentist. Some patients use both.

What if flossing makes my gums bleed?

Bleeding at the start usually indicates that there is inflammation in that area, not that the floss is causing damage. With regular use and correct technique, bleeding generally decreases within a few days to two weeks. If it continues beyond that, concentrates in one area, or occurs together with swelling, assessment is required.

Should I floss before or after brushing?

Either order is acceptable; what matters is doing it regularly. There is a practical argument for flossing first: once the plaque between the teeth is loosened, fluoride reaches the interdental surfaces more easily during brushing. Choosing the order you are least likely to forget matters more than any theoretical advantage.

Does flossing create gaps between teeth?

Used correctly, it does not. The floss is not pressed into the gum but wrapped against the tooth surface and moved gently up and down. Widening of the spaces over time results from gum recession and loss of the tissue between the teeth, not from the floss. Indeed, that process advances faster when plaque is not removed.

Types of Dental Floss and How to Use Them

Why Use Dental Floss?

A toothbrush cleans the front, back and chewing surfaces of the teeth, but it cannot reach well enough into the side surfaces where two teeth touch or just beneath the gum margin. Bacterial plaque builds up most in these areas. Interdental cleaning aids such as floss or interdental brushes remove plaque from these surfaces mechanically.

Research shows that cleaning between the teeth in addition to brushing reduces gum inflammation and bleeding. The evidence for its effect in preventing decay between the teeth is more limited; floss should therefore be considered together with brushing with fluoride toothpaste, reducing how often sugary foods are eaten and regular check-ups.

What Interdental Cleaning Aids Are There?

Which aid is suitable depends on the width of the spaces between the teeth, the condition of the gums and manual dexterity:

1. Floss Picks (Floss on a Handle)

A short piece of floss stretched across a plastic handle. Because it can be used with one hand, it makes things easier for people new to flossing and those with limited dexterity. It is harder to wrap the floss around the side of the tooth than with spool floss, so it should be pressed against each tooth surface separately.

2. Spool (Multifilament) Floss

Made of many fine nylon fibres twisted together; waxed and unwaxed types are available. Because it is wound around the fingers, it is best suited to wrapping around the side of the tooth in a "C" shape. Waxed floss slides more easily where teeth are in tight contact.

3. PTFE (Monofilament) and Spongy Floss

PTFE floss is a single smooth tape; it slides easily through tight contacts and does not fray. Spongy (thickened) floss is suitable under bridges, around implants and in wide spaces; most types have a stiff end that makes it easier to thread under a bridge.

4. Interdental Brush

A small brush thin enough to fit between the teeth. In people with wide spaces between the teeth, gum recession or previous gum treatment, it can be more effective and easier to use than floss. The size should be chosen so that it enters the space without forcing; your dentist can help determine the right size.

5. Water Flosser

It sprays pressurised water to remove food debris and some plaque from between the teeth. It is a helpful aid for people with orthodontic braces, bridges or implant-supported prostheses and those who find flossing difficult. However, because it does not mechanically wipe away plaque stuck to the tooth, in most people it does not fully replace floss or interdental brushes.

How to Floss Correctly

Enough length: Take about 40 cm of floss, wind most of it around the middle finger of one hand and the rest around the middle finger of the other; guide it with your thumbs and index fingers.
Gentle entry: Ease the floss between the teeth with a light back-and-forth sawing motion; do not snap it down onto the gum.
"C" motion: Wrap the floss around the side of one tooth like the letter "C" and scrape upwards from just below the gum margin a few times; then repeat for the neighbouring tooth in the same space.
A clean section for each space: Use a clean section of floss as you move from one space to the next; do not skip the back surfaces of the last teeth.
Frequency: Once a day, preferably with your evening brushing, is enough.

Common Situations

Bleeding gums when flossing

Mild bleeding in the first days is common in people new to flossing and is usually a sign of gum inflammation. With regular, gentle use it usually decreases within a week or two. Stopping flossing because of bleeding allows the inflammation to continue.

Floss catching or shredding in the same place

This may suggest an overhanging filling edge, decay between the teeth, a broken filling or tartar in that area. Shredding once may be unimportant; if it keeps happening, having the area checked at an examination is advised.

When Should You See a Dentist?

Gum bleeding lasting more than two weeks despite regular use
Swelling, pain or discharge from the gums, or a bad taste in the mouth
Gaps between the teeth that keep widening, or a feeling that teeth are loose
Floss repeatedly catching or shredding in the same area
Food getting trapped between the teeth more and more often

Possible causes of gum bleeding are explained in the article on bleeding gums, and professional cleaning on the scaling page.

This article is for general information and does not replace an examination by a dentist. The interdental cleaning aid and size suitable for you can be decided together with your dentist at an examination.