Nine randomised controlled trials (RCTs) were included in the review (n=510 participants). Follow-up ranged from a single use to 12 weeks, with most RCTs reporting four or six week follow-up. For all trials, procedures for concealing treatment allocation were not reported and blinding of participants was not possible.
A significant improvement in plaque scores from baseline was observed for interdental brushes in eight of the nine RCTs. Significant improvements were observed for bleeding scores and probing pocket depth (in those trials that measured these outcomes) and for two of the three studies reporting the Loe and Silness Gingival Index.
A significant difference favouring interdental brush use on plaque was observed for all three RCTs comparing interdental brushing to brushing alone, for five of the eight RCTs comparing interdental brushes to floss, and for one of the two RCTs comparing interdental brushes to woodsticks. Two out of three RCTs found a favourable effect for interdental brushes on pocket depth compared to floss. Data on other outcomes were inconsistent or unreported.
A meta-analysis of RCTs comparing interdental brushes to floss showed a statistically significant effect in favour of interdental brushes on the Silness and Loe plaque index (weighted mean difference -0.48, 95% confidence interval: -0.65 to -0.32; p<0.00001, I2=85.4%). Comparisons of other indices were not statistically significant.
No adverse events were reported.