Impact of Interdental Brushing on Pregnancy‐Associated Gingivitis: A Secondary Analysis of a Randomised Controlled Trial

Aim To assess whether daily use of calibrated interdental brushes can reduce gingival bleeding in pregnant women at high risk of preeclampsia. Materials and Methods In this multi‐centre randomised controlled trial, 323 nulliparous women at risk of preeclampsia and with an intact periodontium were enrolled at 12 weeks of gestation. Participants were randomly allocated (1:1) to either: (i) the intervention group receiving individualised interdental hygiene instructions and calibrated interdental brushes for daily use, or (ii) the control group: receiving routine antenatal care. All participants were recalled at 1 week after baseline, 4, 5 and 8 months of pregnancy for assessments of bleeding on probing (BOP) and other periodontal indices. Linear mixed models were used to assess changes in bleeding over time, and logistic regression was used to evaluate predictors of bleeding resolution at the final follow‐up. Results At 8 months of pregnancy, the intervention group showed a significant reduction in gingival bleeding, from 56% at baseline to 12% (−79.9%, p < 0.001), whereas the control group remained stable. Most of the improvement occurred during the first week (−56.8%). Among participants with severe baseline bleeding (> 81%), the reduction reached 84.3% ( p < 0.05). Longitudinal analysis confirmed sustained reductions at each follow‐up. Interdental brushing was the strongest independent predictor of bleeding reduction (OR = 3.14; 95% CI: 2.01–4.90). Conclusions Daily use of calibrated interdental brushes, introduced early in pregnancy, significantly reduced gingival bleeding with rapid and sustained effects. These findings support the feasibility and clinical relevance of individualised interdental hygiene as a preventive strategy within standard antenatal oral health care. Trial Registration ClinicalTrials.gov NCT04989075 ( https://clinicaltrials.gov/study/NCT04989075 )