Open Access

Birte Holtfreter, Elena Conrad, Thomas Kocher, Sebastian-Edgar Baumeister, Henry Völzke, Alexander Welk

• Aim To estimate association between the use of interdental cleaning aids (IDAs) and type on 7-year follow-up levels of interdental plaque, interdental gingival inflammation, interdental periodontitis severity, the number of interdental sound surfaces and the number of missing teeth in a population-based cohort study. Materials and Methods We used 7-year follow-up data of 2224 participants from the Study of Health in Pomerania (SHIP-TREND). We applied generalized linear and ordinal logistic models, adjusting for confounding and selection bias using inverse probability treatment weighting and multiple imputation. Results Flossers were 32% less likely to have higher interdental plaque (iPlaque) levels than non-users of IDAs (odds ratio [OR] = 0.68; 95% confidence interval [CI]: 0.50–0.94); flossing resulted in 5% lower means of iPlaque. Effects on interdental bleeding on probing (iBOP), mean interdental probing depths and mean interdental clinical attachment levels were direction-consistent but statistically non-significant. Interdental brushing was associated with lower follow-up levels for interdental plaque (OR = 0.73; 95% CI: 0.57–0.93) and iBOP (OR = 0.69; 95% CI: 0.53–0.89). IDAs were more effective in reducing iPlaque in participants with periodontitis, whereas iBOP reduction was more pronounced in participants with no or mild periodontitis. The analyses did not suggest that the use of IDAs affected caries. Finally, applying change score analyses, flossing reduced tooth loss incidence (incidence rate ratio [IRR] = 0.71) compared with non-users of IDAs. Conclusions Recommending flossing and interdental brushing in dental practices represents an approach to the prevention of gingivitis and consequently periodontitis.