BACKGROUND The aim of this single-blinded, parallel-group, randomized clinical trial was to compare the efficacy of electric 3-dimensional (3D) toothbrushes and manual toothbrushes in removing plaque and reducing gingival inflammation in orthodontic patients. METHODS Eighty adolescents with fixed orthodontic appliances in both arches were randomized at a 1:1 ratio, with an equal number of both sexes, in this examiner blinded, parallel clinical trial. Eligibility criteria included subjects aged between 12 and 16 years, good general health, nonextraction orthodontic treatment, and plaque-induced gingivitis, excluding patients with active caries or periodontitis, tooth agenesis, syndromes, disabilities, and craniofacial deformities, ≥2 cervical and/or proximal fillings, dental prostheses or dental implants, and subjects smoking or using antibiotics or medication predisposing to gingival enlargement. Patients were assigned to use either an electric 3D orthodontic toothbrush (Oral-B Pro-1000 with Oral-B Ortho head; Procter & Gamble, Cincinnati, Ohio) or a manual toothbrush (Oral-B Orthodontic brush; Procter & Gamble) and instructed to brush twice daily for 2 minutes. The main outcomes were: (1) plaque removal, assessed with the Modified Silness and Löe plaque index and the Modified Full Mouth Plaque Score, and (2) gingival inflammation reduction, assessed with the Modified Silness and Löe Gingival Index and the Modified Simplified Gingival Index. Measurements were taken at baseline, 1, 2, and 3 months. Randomization was achieved with 2 random sequences, one for each brush, written and sealed in opaque numbered envelopes. Blinding was possible for outcome assessment only. RESULTS Considerable variability was observed among patients in the values of all dependent variables. There was no difference between interventions over time for any of the outcomes, and the main effects for treatment and time were also not statistically significant. For Modified Silness and Löe plaque index, the interaction was 0.001 (95% confidence interval, -0.011 to 0.013; P = 0.89). CONCLUSIONS No difference in plaque removal efficacy and gingival inflammation reduction was found between the electric 3D and manual toothbrushes in adolescents with fixed orthodontic appliances. Therefore, orthodontists should focus on enhancing their patients' dental awareness and oral hygiene, along with professional prophylaxis and other oral hygiene aids, independently of the brush used. BACKGROUND This trial was registered at ClinicalTrials.gov (Identifier: NCT02699931). METHODS The protocol was not published before trial commencement. BACKGROUND Electric and manual toothbrushes and toothpastes for all participants were provided by Procter & Gamble (Oral-B). Miscellaneous costs were covered by the participating departments.