This examiner-blind clinical study evaluated the efficacy of a new battery-powered toothbrush with oscillating head (Colgate Actibrush) on established gingivitis and plaque at 15 days and again at 30 days, as compared to a control manual toothbrush (American Dental Association [ADA]-provided toothbrush, full head, soft bristles). A total of 63 participants completed the study. They were stratified into two balanced groups according to their mean baseline prebrushing plaque scores and were randomly assigned to use the battery-powered test toothbrush or the manual control toothbrush. Participants were instructed to brush their teeth twice daily (mornings and evenings) for 1 minute with their assigned toothbrush for the 30-day duration of the study. Gingivitis and plaque (pre- and postbrushing) examinations were conducted by the same dental examiner at baseline, after 15 days, and again after 30 days. The Colgate Actibrush demonstrated a significantly greater reduction of plaque (46.53%) and gingivitis (18.57%) when compared to the ADA-provided toothbrush after 30 days of use. Additionally, a comparison of the plaque scores for the battery-powered toothbrush at 15 and 30 days shows a continued reduction in plaque of more than 25% for a cumulative difference from baseline of 73%. These results support the conclusion that the new battery-powered toothbrush is clinically superior in plaque removal efficacy and gingivitis efficacy to the manual toothbrush, and continues to significantly improve plaque scores even up to 30 days of use.