When Cleaning Between Teeth Does More Harm Than Good
A closer look at how interdental brushes and toothpaste can wear down dentine
Keeping Teeth Clean—But at What Cost?
Interdental brushes have become a popular tool for cleaning the hard-to-reach spaces between teeth. Dentists often recommend them because they remove plaque more effectively than floss in many situations. However, as more people use interdental brushes daily, an important question arises: can these tools damage tooth structure when used incorrectly—especially with toothpaste?
A recent laboratory study from researchers at the University of Zurich set out to explore this issue by examining how different interdental brushes affect enamel and dentine when used with and without toothpaste.
Why Tooth Wear Matters
Thanks to decades of preventive care, tooth decay has decreased dramatically. As a result, dental professionals now see more non-carious tooth surface loss, such as abrasion. Abrasion occurs when tooth structure is worn away by mechanical forces—often from oral hygiene products themselves.
Dentine, which lies beneath enamel and is frequently exposed in older adults due to gum recession, is especially vulnerable. While toothbrush abrasion has been widely studied, the impact of interdental brushes on tooth wear remains poorly understood.
What Did the Researchers Do?
In this laboratory (in-vitro) study, researchers tested three commonly used interdental brushes of the same ISO size but with different designs:
Curaprox
Elmex
Circum
A total of 144 tooth samples (72 enamel and 72 dentine specimens) were prepared from bovine teeth, a well-established substitute for human teeth in dental research.
The samples were brushed under controlled conditions using:
Artificial saliva, or
A toothpaste slurry made from Colgate Total Original
Brushing simulated long-term use:
Enamel samples were brushed for the equivalent of 30 years of daily cleaning
Dentine samples for approximately 5 years
Tooth wear was then measured precisely using surface profilometry and scanning electron microscopy.
What Did They Find?
The results were striking:
Enamel remained largely unaffected, regardless of whether toothpaste was used.
Dentine told a very different story.
When interdental brushes were used without toothpaste, dentine wear was negligible.
However, when toothpaste was added, significant dentine abrasion occurred.
Importantly, the amount of wear depended on the brush design:
Elmex caused the greatest dentine wear
Curaprox and Circum caused significantly less damage
This suggests that factors such as bristle stiffness and brush construction play a major role—not just brush size.
Why Does Toothpaste Make a Difference?
Toothpaste contains abrasive particles designed to remove plaque and stains. While these abrasives are generally safe for enamel, dentine is much softer and more easily worn away.
The toothpaste used in this study has a high relative dentine abrasivity (RDA), which likely amplified the damage when combined with interdental brushing. Over time, this type of wear could contribute to tooth sensitivity and structural loss.
What Does This Mean for Daily Oral Care?
The study sends a clear message:
👉 Interdental brushes should not be used with toothpaste on exposed dentine.
Instead:
Use interdental brushes without toothpaste
Follow proper technique and frequency
Seek professional guidance, especially if you have gum recession or sensitive teeth
Correct instruction is essential to gain the benefits of interdental cleaning without unintended harm.
Take-Home Message
Interdental brushes are effective tools—but when combined with toothpaste, they can cause significant dentine abrasion, depending on brush design. Used improperly over time, they may do more harm than good.
Smart oral hygiene isn’t just about cleaning more—it’s about cleaning wisely.
Original Article Reference
Marconi C, Gubler A, Wegehaupt FJ, Schmidlin PR.
The Influence of Interdental Brushes and Toothpaste on Approximal Enamel and Dentine Abrasion – A Laboratory Study.
Oral Health & Preventive Dentistry. 2025;23:217–224.
DOI: 10.3290/j.ohpd.c_1955