How much plaque does flossing actually remove?
Short answer: Brushing alone cannot reach the surfaces between your teeth, which make up roughly 40% of each tooth. Those contact points are where cavities and gum disease most commonly begin. Daily flossing or interdental cleaning is the only practical way to remove plaque from them — which is why it matters far more than its reputation suggests.
The 40% your brush never touches
A toothbrush cleans three of the five surfaces of a tooth reasonably well: the outer, inner and biting surfaces. It cannot get into the two surfaces where the tooth touches its neighbours, because the bristles physically cannot fit.
Those interproximal surfaces account for approximately 40% of the total tooth surface — and they are disproportionately where problems start, because plaque sits there undisturbed and food packs in.
You can brush impeccably twice a day and still leave a substantial share of your mouth uncleaned.
What it prevents
- Interproximal cavities — decay between teeth, which typically cannot be seen without an X-ray and is often well advanced by the time it is felt
- Gingivitis — inflamed, bleeding gums caused by plaque along and just under the gumline
- Tartar build-up — plaque left in place hardens within days and can then only be removed professionally
- Bad breath — trapped food and bacteria between teeth are a frequent and easily fixed cause
Doing it so it works
- Curve, do not saw. Guide the floss between the teeth, then curve it into a C-shape hugging the side of one tooth. Slide gently just under the gumline, then repeat against the neighbouring tooth.
- Use a fresh section for each gap.
- Do not snap it down into the gum — that causes the trauma people wrongly blame for their bleeding.
- Once a day is enough. Plaque takes roughly 24 hours to reorganise, so consistency beats frequency.
- Timing is up to you. The best time to floss is whenever you will actually do it. Many people find night-time works because it removes the day's debris before hours of reduced saliva flow.
If you hate floss
Then use something else. The objective is cleaning between the teeth, not the string specifically. Interdental brushes are often more effective than floss where there is space for them, and many people find them far easier. Floss picks are better than nothing and much better than skipping. Water flossers are useful, particularly around braces and bridges.
The best interdental tool is the one you will use every day.
Common questions
Is flossing really necessary if I brush well?
Yes. Brushing cannot physically reach the surfaces between teeth, which is roughly 40% of each tooth and where a large share of cavities and gum disease begin.
Should I floss before or after brushing?
Either works. What matters far more is that it happens daily. Some evidence favours flossing first so fluoride toothpaste can then reach the newly cleaned surfaces.
Are interdental brushes better than floss?
Where there is enough space between the teeth, interdental brushes are often more effective and easier to use. Floss remains better for very tight contacts. We can advise which suits your mouth.
How long should flossing take?
Done properly, one to two minutes. It is quicker than most people assume once the technique becomes habit.