Reports & Studies

What does interdental cleaning achieve in the long term?

PD Dr. Kristina Bertl, PhD MSc MBA

When patients ask us about the necessary oral hygiene items, the recommendation from a dentist’s perspective is always relatively clear: interdental cleaning is essential – just brushing your teeth alone is not enough!

And there are numerous studies to back up this claim; however, the majority of them only focus on a shorter time frame, such as 4 weeks, 3 months, 6 months or 1 year. But does this claim also hold up over the long term? One study from Germany evaluated data from over 2,200 people over a 7-year period and examined the actual effect of interdental cleaning in comparison to general teeth cleaning (Holtfreter et al. 2024). In terms of interdental cleaning, a distinction was made between dental floss, toothpicks and interdental brushes. Of the total of 2,224 people studied, 1,576 did not use any form of interdental cleaning, which equates to 71%! Of the 648 people who stated that they do perform interdental cleaning, 230 used dental floss, 156 used toothpicks and 262 interdental brushes. Data collected during the study included interdental plaque and bleeding values and the probing depths, as well as the rate of tooth loss.

Tooth with toothbrushes, dental floss sticks and interdental brush.
What does interdental cleaning achieve in the long term?

People who either used dental floss or interdental brushes showed a significant reduction in plaque in the interdental area – 32 and 27% respectively – at the 7-year follow-up examination. A similarly positive, albeit partly statistically insignificant, effect could also be seen in relation to the interdental bleeding indices and probing depths. Interdental cleaning was highly effective in relation to plaque reduction, above all in people with periodontitis. There was also another very interesting result: The regular use of dental floss significantly reduced the risk of tooth loss by 29%!

What conclusions can we draw from this study? In principle, tried-and-trusted knowledge is backed up by more meaningful long-term data: Interdental cleaning leads to significantly reduced plaque values in the interdental area. There was also a similar effect on bleeding values and probing depths. Unfortunately, it was also revealed that approx. 70% of the population studied are still not performing interdental cleaning – this means that dental teams still need to provide a lot of information, instruction and motivation. It is always difficult to statistically prove a tangible effect on concrete endpoints such as cavities or tooth loss, but the authors of this study did succeed in showing that people who regularly use dental floss had a significantly lower rate of tooth loss after 7 years.


  1. Holtfreter, B., Conrad, E., Kocher, T., Baumeister, S.-E., Völzke, H., & Welk, A. (2024). Interdental cleaning aids are beneficial for oral health at 7-year follow-up: Results from the Study of Health in Pomerania (SHIP-TREND). Journal of Clinical Periodontology, 51(3), 252–264.