Background: Interdental rubber picks (IRP) have become a frequent and convenient alternative for interdental cleaning. However, only little evidence exists supporting the effectiveness of newer designs available on the market. Therefore, a new in vitro model was evaluated to measure the experimental cleaning efficacy (ECE), as well as the force needed for insertion and during the use of IRP, with high reproducibility. Methods: Five different sizes of commercially marketed IRP with elastomeric fingers (IRP-F) (GUM SOFT-PICKS® Advanced, Sunstar Deutschland GmbH, Schönau, Germany) or slats (IRP-S) (TePe EasyPick™, TePe D-A-CH GmbH, Hamburg, Germany) were tested. Interdental tooth surfaces were reproduced by a 3D-printer (Form 2, Formlabs Sommerville, MA, USA) according to human teeth and matched to morphologically equivalent pairs (isosceles triangle, concave, convex) fitting to different gap sizes (1.0 mm, 1.1 mm, 1.3 mm). The pre−/post brushing situations at interdental areas (standardized cleaning, computer aided ten cycles) were photographically recorded and quantified by digital image subtraction to calculate ECE [%]. Forces were registered with a load cell [N]. Results: IRP-F have to be inserted with significant higher forces of 3.2 ± 1.8 N compared to IRP-S (2.0 ± 1.6 N; p < 0.001) independent of the size and type of artificial interdental area. During cleaning process IRP-S showed significantly lower values for pushing/pulling (1.0 ± 0.8 N/0.5 ± 0.4 N) compared to IRP-F (1.6 ± 0.8 N/0.7 ± 0.3 N; p < 0.001) concomitant to significantly lower ECE (19.1 ± 9.8 vs. 21.7 ± 10.0%, p = 0.002). Highest ECE was measured with largest size of IRP-F/IRP-S independent the morphology of interdental area. Conclusions: New interdental cleaning aids can be tested by the new experimental setup supported by 3D printing technology. Within the limitations of an in vitro study, IRP-F cleaned more effectively at higher forces compared to IRP-S.

Background Interdental brushes (IDB) are according to the actual evidence the first choice for cleaning interdental areas (IDR). Their size should be chosen individually according to the IDR morphology. However, interdental rubber picks (IRP) are appreciated better by the patients and are hence becoming more and more popular but the evidence regarding their efficacy is still limited. The aim of this in vitro study was to measure the experimental cleaning efficacy (ECE) and force (ECF) during the use of interdental brushes versus newer wireless types with rubber filaments (IRP), both fitted and non-fitted for different IDR. Methods The medium size of a conical IRP (regular, ISO 2) with elastomeric fingers versus four sizes (ISO 1, 2, 3, 4) of cylindric IDB with nylon filaments (all Sunstar Suisse SA, Etoy, Switzerland) were tested. Interdental tooth surfaces were reproduced by a 3D-printer (Form 2, Formlabs Sommerville, MA, USA) according to human teeth and matched to morphologically equivalent pairs (isosceles triangle, concave, convex) fitting to three different gap sizes (1.0 mm, 1.1 mm, 1.3 mm). The pre-/post brushing situations at IDR (standardized, computer aided ten cycles) were photographically recorded and quantified by digital image subtraction to calculate ECE [%]. ECF were registered with a load cell [N]. Results Overall, a higher ECE was recorded for IDB compared to IRP (58.3 ± 14.9% versus 18.4 ± 10.1%; p < 0.001). ECE significantly depended on the fitting of the IDB. ECE was significant higher in isosceles triangle compared to concave and convex IDR for both IDB and IRP (p ≤ 0.001). ECF was lower for IDB (0.6 ± 0.4N) compared to IRP (0.8 ± 0.5N; p ≤ 0.001). ECE in relation to ECF increases with smaller IDB. For IRP highest values of ECF were found in the smallest IDR. Conclusions Within the limitations of an in vitro study, size fitted IDB cleaned more effectively at lower forces compared to conical IRP.