Interdental brushes for improving oral hygiene in patients with fixed orthodontic appliances: a systematic review

Background An interdental brush (IDB) is an adjunctive oral-hygiene tool designed to clean interproximal spaces and remove dental plaque. This study systematically evaluated its effectiveness for improving oral hygiene and periodontal health among orthodontic patients. Methods A systematic search was conducted across five databases including PubMed, EMBASE, Cochrane, Web of Science, Scopus up to 30 August 2025. Randomized controlled trials enrolling orthodontic patients that compared IDB with other adjunctive oral-hygiene aids or with no adjunctive were included. The primary endpoint was periodontal condition, measured by periodontal indices. We assessed risk of bias with the Cochrane risk of bias tool. Given clinical and methodological heterogeneity, findings were synthesized narratively following SWiM guidance. The certainty of evidence for primary outcomes was evaluated using the GRADE framework. Results Six studies with a total of 442 orthodontic patients were included in the systematic review. Low-certainty evidence from individual studies suggested that IDB may reduce plaque and gingival inflammation compared with toothbrushing alone or floss. Greater benefits were observed when IDBs were combined with orthodontic toothbrushes, whereas no consistent advantage was demonstrated over monotufted brushes or oral irrigators. Outcome measures and indices varied substantially across trials, follow-up periods were generally short, and safety outcomes were rarely reported. These limitations restricted the ability to pool results and lowered the certainty of evidence. Conclusion Low-certainty evidence from a limited number of heterogeneous trials provides only tentative indications that interdental brushes may help improve gingival health and plaque control in orthodontic patients—particularly when used with orthodontic toothbrushes. High-quality, multicenter trials with standardized protocols and longer follow-up are needed to guide clinical recommendations. Systematic Review Registration https://www.crd.york.ac.uk/PROSPERO/view/CRD420251136657 , identifier CRD420251136657.