Interplay Between the In-Vitro Cleaning Performance and Wear of Manual Toothbrushes in Fixed Orthodontic Appliances

Purpose: To investigate the impact of manual toothbrush usage duration and associated wear on cleaning performance in a tooth model with fixed orthodontic appliances.
Materials and Methods: Black resin teeth with attached brackets were coated with a white layer of titanium dioxide and subjected to brushing using a brushing machine. Two distinct brushing motions, horizontal and circular, were tested. Following each brushing session, the percentage of cleaned areas (total and adjacent to the bracket) was measured to determine the cleaning performance of the toothbrushes. Usage was simulated using a 3D-printed tooth relief with brackets and wire. Cleaning performance was re-evaluated after simulated 2, 4, 6, 12, 18 and 24 months of usage, and toothbrush wear was quantified respectively.
Results: Cleaning performance of all investigated brushing motions and tooth areas improved during the test period, although statistical significance was only reached for horizontal brushing. Furthermore, horizontal brushing proved more effective regarding total tooth area and the area adjacent to the bracket compared to circular brushing.
Conclusion: This in-vitro data shows that toothbrushes may feature sufficient or even improved cleaning performance on teeth with orthodontic appliances even after 24 months. However, direct transferability into the clinical setting is limited, as in-vivo toothbrush wear is complex and depends on individual patient habits, and other factors might necessitate an earlier toothbrush change. Nevertheless, this study suggests that cleaning performance and thus oral hygiene in patients with orthodontic appliances may not be critically dependent on usage duration and visual appearance of the toothbrush itself. Keywords: oral hygiene, cleaning performance, toothbrush wear, orthodontic appliances