This study compared counterrotational-action power toothbrushing with manual toothbrushing in effectiveness on plaque control and gingival health in 20 randomly selected orthodontic patients at the University of Missouri-Kansas City. A blind two-group crossover design was used. Gingival and plaque scores were recorded, and a prophylaxis was given to bring the plaque score to zero. Ten subjects received counterrotational power brushes, and ten subjects received manual brushes. Instructions appropriate to each brushing method were given by a hygienist. At 30 and 60 days, plaque and gingival scores were recorded and a prophylaxis was given. At 60 days the subjects who were using power brushes were switched to manual brushes, and the subjects who were using manual brushes were switched to power brushes. At 30 and 60 days, plaque and gingival scores were recorded and a prophylaxis was given. Plaque and gingival scores were significantly less (p less than 0.01) after brushing 2 months with the counterrotational power brush than with the manual brush. This finding was irrespective of the sequence in which the brushes were used.