Impact of Bristle Hardness of Manual Toothbrushes on the Cleaning Efficacy of Teeth with Fixed Orthodontic Appliances.

PURPOSE: To evaluate the influence of bristle hardness (soft or medium) and simulated aging of manual toothbrushes on the cleaning efficacy in teeth with fixed orthodontic appliances. MATERIALS AND METHODS: Brackets were attached to black resin teeth coated with a layer of titanium dioxide and brushed using a soft and medium toothbrush. Two different brushing motions, horizontal and circular, were tested. After every brushing session, the percentage of cleaned areas was measured to evaluate the cleaning performance. Brushing with the respective toothbrushes on a 3D-printed typodont with brackets and wire was performed to simulate the aging of the brush. Cleaning performance was reassessed after simulated periods of two, four and six months. Statistical analysis was performed at baseline and after six months of simulated use, using beta regression and pairwise comparisons. RESULTS: Toothbrushes with softer bristles consistently cleaned more effectively than harder ones, regardless of brushing motion (p 0.0001, respectively). At all timepoints, horizontal brushing was also more effective than circular brushing. The cleaning performance for all bristle types and brushing motions improved over the test period. CONCLUSION: Softer bristles consistently outperformed harder ones, indicating potential benefits for patients with orthodontic appliances. While horizontal brushing was more effective than circular motions, the direct application to clinical settings is limited due to the complexity of in-vivo toothbrush wear and individual brushing habits. Nonetheless, the choice of softer bristles and horizontal brushing techniques may increase the cleaning efficacy on orthodontic appliances.