Bilateral interdental cleaning after powered toothbrushing: an in vitro comparison of interdental brushes and elastomeric interdental picks

Abstract Background Plaque removal in interdental areas (IDR) remains limited when using powered toothbrushing (PT) alone. Although adjunctive interdental cleaning is widely recommended, quantitative data on the incremental benefit of bilateral interdental application are limited. This in vitro study evaluated cleaning potential following sequential interdental cleaning after PT and compared the bilateral incremental effect between interdental brushes (IDB) and elastomeric interdental picks (IDP). Methods A validated in vitro model (verified for reproducibility and standardised quantitative ECE measurement under controlled in vitro conditions) using a standardised artificial biofilm model to quantify interdental experimental cleaning efficacy (ECE, %). Replicated IDRs of different morphologies and sizes simulating open posterior IDR with reduced papillary support were cleaned sequentially using PT alone, PT followed by one-sided interdental application, and PT followed by bilateral interdental application. The primary outcome was the total incremental cleaning effect after PT (ΔECE2). The additional benefit of second-side application (ΔECE3) was analysed as endpoint. Data were analysed using non-parametric tests with Bonferroni correction. Results PT alone resulted in low interdental cleaning efficacy (IDB/ IDP series: 7.5 ± 2.7%/ 10.2 ± 4.1%; p < 0.001). Following bilateral interdental cleaning, overall ECE increased to 81.2 ± 18.3% for IDB (IDP: 54.7 ± 17.6%; p < 0.001). The total incremental effect after PT was significantly greater for IDB (ΔECE2 73.7 ± 17.8%) than for IDP (44.5 ± 20.6%; p < 0.001). In contrast, the additional benefit of second-side application was greater for IDP vs. IDB (ΔECE3: 21.4 ± 14.1% vs. 9.5 ± 12.2%; p < 0.001). The superiority of IDB in total cleaning efficacy was consistent across IDR morphologies and sizes. Conclusions Within the limitations of this in vitro study, PT alone was insufficient for effective cleaning of simulated open posterior interdental areas with reduced papillary support. Cylindric IDBs demonstrated superior overall performance across all tested conditions, while conical IDPs derived a comparatively greater relative benefit from bilateral access.