New Options for Subgingival Oral Hygiene with a Flattened Interdental Brush Design – In Vitro Examination and Case Report

Purpose: The subgingival area is only reached to a limited extent during home oral hygiene with the aids available to date. The question was investigated whether a newly developed, flattened cross-sectional design of interdental brushes (IDBs) can extend their subgingival reach.
Materials and Methods: In part I, the passage-hole diameters (PHD) of IDBs of different sizes and side-bristle lengths, with circular and flattened cross-sections, were compared according to the ISO standard 16409/2016. In part II, handling of flattened IDBs was described based on a case report of a patient with generalised stage 4, grade C periodontitis with locally persistent pockets.
Results: Depending on the brush’s size, flattening of IDBs reduced the PHD by 1-18 intervals. IDBs with longer side bristles could thus be inserted into interdental spaces with equal force. This may increase the potential range of IDBs in the vertical dimension. Regular instruction and check-ups are necessary to enable correct handling, as the flattened brushes can only be used in two positions. The observations documented in the case report (duration: 1.5 years) showed that flattened IDBs were associated with reduced signs of inflammation (reduction of pocket depths from 6 to 3 mm, absence of bleeding on probing).
Conclusion: IDBs with a flattened cross-sectional design have not been previously described in the literature. It was shown that flattening of IDBs leads to a size-dependent decrease in PHD. Based on a case report, it was hypothesised that the design change of the IDBs could be clinically relevant in the case of persistent deep pockets in narrow interdental spaces. However, this can only be verified or falsified by clinical studies.