Interdental brushes or dental floss: your dentist has probably asked you that question already. The two tools share the same goal — cleaning the spaces between your teeth that a toothbrush never touches — but they are not equally suited to every mouth. Choosing between interdental brushes and dental floss depends above all on the size of your interdental spaces. Here is how to decide sensibly.
Why these spaces deserve your full attention
A toothbrush only cleans three faces of each tooth. The side faces, the ones touching their neighbours, almost entirely escape it. As a result, it is in those nooks that plaque builds up, causing cavities between the teeth and gum inflammation. Cleaning these areas every day is not a comfort detail, it is a pillar of prevention.
That leaves choosing the right tool. And here, the geometry of your mouth has a say.
Dental floss: for tight spaces
Dental floss is thin and slips in where nothing else can. When your teeth are well aligned and tightly packed, with narrow gaps, floss is often the only tool able to get in there.
- Its strengths: ideal for tight contacts between teeth, precise mechanical contact against each wall, cheap and compact.
- Its limits: it takes dexterity, it can shred on rough teeth or crowns, and it is less effective when spaces are wide (it does not “fill” the gap and leaves plaque on the sides).
Interdental brushes: for wider spaces
An interdental brush looks like a tiny bottle brush that you slide between two teeth. It comes in several diameters, and that is precisely its strength: when the space is big enough, it “fills” the volume and cleans the side walls far more thoroughly than floss can.
They shine in particular for people with more open spaces (with age, gums often recede), with braces, bridges or implants. Many people also find them easier to handle than floss. You will find everything you need to restock in our collection of toothbrushes and replacement heads.
- Their strengths: very thorough cleaning of wide spaces, easy to handle, excellent around braces, bridges and implants.
- Their limits: they need the right diameter (too big and they force their way in and hurt the gum; too small and they do not clean), and they will not pass through very tight contacts.
Interdental brushes or dental floss: the comparison
| Situation | Dental floss | Interdental brushes |
|---|---|---|
| Tight, well-aligned teeth | Recommended | Often impossible to insert |
| Wide spaces, receding gums | Cleans the sides poorly | Recommended, very thorough |
| Braces, bridge, implant | Awkward | Very well suited |
| Ease of handling | Takes technique | Generally simpler |
| Choice of size | One size only | Several diameters to match |
The key message: it is not “one is better than the other in absolute terms”, but “which one matches the size of your gaps”. Many mouths in fact need both: floss for the tight areas at the front, interdental brushes for the more open spaces at the back.
And where does the water flosser fit in?
A third player deserves its place: the water flosser. Its pulsed jet of water cleans and massages the gums, and it excels exactly where floss and interdental brushes are hard to manoeuvre — around braces, bridges and crowns. Our Fairywill 5020E water flosser, with its adjustable intensity and interchangeable tips, is a very good complement to mechanical cleaning: it rinses away the debris that the brush or floss has loosened and reaches the far corners at the back of the mouth. It does not fully replace the mechanical contact of floss or an interdental brush on stubborn plaque, but as a pair, effectiveness climbs markedly.
The smart move: ask your dentist or hygienist to measure your interdental spaces. They will tell you which brush diameter to use and where floss remains necessary, saving you months of trial and error.
How to use each tool properly
The best tool, badly used, loses most of its value. A few simple pointers are worth more than a long speech:
- Dental floss: unwind a decent length, guide it gently between two teeth without snapping it onto the gum, then hug the curve of each tooth in a “C” shape to scrape the wall from top to bottom. Move to a fresh section of floss for each gap.
- The interdental brush: insert it horizontally, without forcing, with a few gentle back-and-forth movements. If you have to press hard to get it in, the diameter is too big; if it floats, it is too small.
- The water flosser: aim the jet along the gum line and into each space, leaning over the basin, starting at low intensity.
In every case, consistency beats technical perfection: an imperfect but daily habit protects you far better than a flawless one performed once a week. Take the time to find your rhythm, even if that means starting with the easiest areas before extending to the whole mouth.
Your questions about interdental brushes and dental floss
Do interdental brushes completely replace dental floss?
Not always. On tight teeth where a brush will not go, floss remains essential. In wide spaces, interdental brushes clean better. Many people combine the two depending on the area of the mouth.
How do I choose the right brush diameter?
The brush should go in with slight resistance, without forcing or hurting the gum. Too small and it does not clean; too big and it damages. Your dentist can tell you which diameters suit you, sometimes different ones for different areas.
Do interdental brushes make gums bleed?
At first, inflamed gums may bleed a little, just as with floss. This usually eases within one to two weeks as the gum firms up. If the bleeding persists, get it checked.
How often should an interdental brush be replaced?
As soon as the bristles flatten or the wire bends, often after a few days to a week of use. Always keep spares to hand so you never skip a step.
In summary
Interdental brushes or dental floss? It all depends on your gaps: floss for tight contacts, interdental brushes for wide spaces, braces and bridges — and often both, area by area. The Fairywill 5020E water flosser rounds out the set, while our collection of replacement heads helps you never run short of supplies. The best choice is still the one you will use every day. To pull it all together, follow our complete guide to an oral care routine, and take the toothpaste quiz to complete your routine with the right formula.