Interdental brushes have the strongest evidence of the three, but only where the gaps between your teeth are wide enough to take one. String floss suits tight contacts. Water flossers are easy to use and helpful around braces, bridges and implants, although the research behind them is thinner than the marketing suggests. For most people, the tool that wins is the one they will actually use every day.
Why the gaps need their own tool
A toothbrush cleans the outer, inner and biting surfaces of your teeth well, but its bristles do not get far into the spaces where two teeth touch. Plaque left there can lead to gum inflammation and decay between the teeth, which is often found only on an X-ray. That is why dentists and OHTs recommend cleaning between the teeth once a day, as well as brushing twice a day with fluoride toothpaste.
What the Cochrane review found
The most thorough summary of the evidence is a Cochrane review by Worthington and colleagues (2019), which pooled 35 trials in adults. Its key findings were:
- Using floss or interdental brushes as well as brushing may reduce gum inflammation or plaque, or both, compared with brushing alone.
- Interdental brushes may be more effective than floss.
- Evidence for water flossers (oral irrigators) and cleaning sticks was limited and inconsistent. Water flossers reduced gum inflammation at one month in some trials, but not clearly at three or six months, and did not clearly reduce plaque.
The authors rated the overall evidence as low to very low certainty. Most trials were short and involved people with fairly healthy gums, so the differences between tools may be smaller in everyday life than the numbers suggest. None of this means water flossers are useless. It means they have been studied less, and the trials so far have not shown a clear long-term edge.
Interdental brushes: best where they fit
These tiny bristled brushes come in a range of sizes. Where the space is wide enough, they scrub the tooth surfaces on either side and reach into the slight hollows that floss can skim over. They are often the first choice for people with gum disease, receding gums or larger spaces between back teeth.
Size matters. A brush that is too small does little, and one that is too large can hurt or damage the gum. Many people need two or three sizes for different parts of the mouth, and a dentist or OHT can measure this for you at a check-up.
String floss: the option for tight contacts
Floss is cheap, fits in a pocket and slides through contacts that are too tight for a brush. Its drawback is technique. Curving the floss around each tooth and taking it gently just under the gum takes practice, and many people find it fiddly enough to give up. Our guide to flossing properly walks through the method step by step.
Water flossers: easier for some mouths
A water flosser sends a pulsing jet of water between the teeth and along the gum line. It does not scrape plaque off the way a brush or floss does, but it flushes out food and loose debris and many people find it comfortable. It can be especially handy around braces, under bridges and around implants, and for people with arthritis or limited hand movement. The downsides are cost, bench space and a bit of splashing while you learn.
If you wear fixed braces or have a bridge and prefer a manual option, floss threaders and superfloss are another way in, covered in our article on floss threaders and superfloss.
Side by side
| Tool | Suits | Evidence | Watch out for |
|---|---|---|---|
| Interdental brushes | Wider gaps, gum disease, receding gums | Strongest of the three, low certainty | Must be sized correctly; will not fit tight contacts |
| String floss | Tight contacts, travel | May reduce gum inflammation when added to brushing | Technique takes practice |
| Water flosser | Braces, bridges, implants, limited dexterity | Limited and inconsistent | Cost, bench space, does not scrub surfaces |
Matching the tool to your mouth
Many people end up using a combination: interdental brushes for the back teeth where gaps are larger, and floss for tight front teeth. If you have struggled to keep up any routine at all, starting with the tool you find easiest is better than putting off the one that looks best on paper. You can add or swap tools later.
Between-teeth cleaning works alongside good brushing, which our guide on how to brush properly explains. If your gums bleed when you start, that is common in the first few days. Healthdirect advises seeing a dentist or OHT if bleeding continues after 3 to 4 days of good brushing and flossing, and our article on bleeding gums explains the likely causes.
What patients ask about cleaning between teeth
Can a water flosser replace floss?
For some people, particularly those with braces, bridges or implants, or who find floss too difficult, a water flosser can be the main between-teeth tool. The evidence for it is weaker than for interdental brushes, so ask your dentist or OHT whether adding a brush in the wider gaps would help.
Are interdental brushes better than floss?
Where they fit, the Cochrane review suggests they may be more effective. In very tight spaces, floss reaches where a brush cannot.
Do I still need to brush if I clean between my teeth?
Yes. Brushing and between-teeth cleaning do different jobs, and you need both.
Get help choosing your tools
If you would like help choosing and sizing between-teeth tools, a dentist or OHT at Lumi Dental in Melrose Park can show you what fits your mouth. Get in touch, read about our general dental care, or see current offers on our deals page.
