Interdental brushes are one of the most clinically endorsed but least consumer-marketed oral hygiene tools available. Despite multiple systematic reviews showing they outperform floss for plaque removal in adults with any gum recession or larger interdental spaces, most people have never been shown how to use them. Here is the evidence and the practical guidance.
What the research shows
A 2019 Cochrane review of 35 randomized trials comparing interdental cleaning methods found that interdental brushes were significantly more effective than floss for reducing plaque and bleeding on probing in adults. A 2015 systematic review found similar results with interdental brushes outperforming floss for gingivitis reduction. The advantage is most pronounced in adults with any gum recession creating space between teeth and their gum line. In younger adults with tight contacts and no recession string floss remains effective and may be preferable.
Why they outperform floss in the right situation
In someone with some gum recession even a small amount the space between the tooth surface and the gum line in the interdental area widens. String floss passes through this space without necessarily contacting the concave root surfaces or the embrasure that widens below the contact point. An interdental brush of the correct size fills this space and contacts the curved root surfaces on both sides of the space simultaneously. This is a significant mechanical advantage for cleaning the actual surface area that matters.
Choosing the right size
Interdental brushes come in multiple sizes from very small to quite large. The correct size fits through the interdental space with light resistance and contacts both adjacent tooth surfaces. If the brush goes through too easily it is not cleaning the surfaces adequately. If it will not fit it is too large. Most people need different sizes for different areas of their mouth as interdental spaces vary significantly around the arch. Your dentist or hygienist can guide you on sizing during your next appointment.
How to use them
Insert the brush into the interdental space and move it back and forth with a gentle in-and-out motion. No paste is necessary though some fluoride gel can be applied to the brush to deliver fluoride to interdental surfaces. Clean the brush under running water between spaces. Replace when the bristles are bent or worn. Use once daily at minimum with evening being preferable since overnight bacterial activity on cleaned surfaces is less harmful than overnight activity on uncleaned surfaces.
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Educational content. Ask your dentist or hygienist for guidance on which interdental cleaning method and size is most appropriate for your specific anatomy.
