To assess the plaque removal efficacy of an oscillating-rotating power brush relative to a newly- introduced sonic power brush. Methods: This study used a randomized, examiner-blind, single-center, two-treatment, parallel group 4-week design. Subjects with pre-existing plaque scores of at least 1.75 on the Turesky Modification of the Quigley-Hein Plaque Index (TMQHPI) were evaluated for baseline whole mouth and approximal plaque scores. They received either the oscillating-rotating brush (Oral-B Professional Care 1000, sold as Oral-B Professional Care 600 in some regions, with the Oral-B Precision Clean brush head, D16u/EB2O) or the sonic brush (Colgate ProClinical C200 with Colgate Triple Clean brush head) and brushed twice-daily with the assigned brush and a standard fluoride dentifrice for 4 weeks before returning for plaque measurements. Prior to baseline and the Week 4 measurements, participants abstained from oral hygiene for 12 hours and from eating, chewing gum and drinking for 4 hours. Results: A total of 131 subjects were enrolled in the study at baseline, with all completing the study: 65 in the oscillating-rotating group, and 66 in the sonic group. Both brushes significantly reduced plaque over the 4-week study period. The oscillating-rotating brush was statistically significantly more effective in reducing plaque (P< 0.001) than the sonic brush. Compared to the sonic power brush, the adjusted mean plaque reduction scores for the oscillating-rotating power brush were more than five times greater for whole mouth and approximal areas.