The purpose of this study was to compare the subgingival and interproximal plaque removal of a manual toothbrush to that of an oscillating counter-rotational electric toothbrush. Ninety teeth were divided into control, manual, and electric groups and test teeth received a total of 20 seconds of brushing. The teeth were then anesthetized, extracted, stained, dried, and examined with a computer-assisted video analysis system. The control group had 13.88% plaque-free interproximal surfaces, compared to 30.57% for the manual group and 53.23% for the electric group. The mean subgingival plaque-free measurement was 0.05 mm for the control group, 0.64 mm for the manual group, and 1.36 mm for the electric group. The differences between the means were statistically significant for both measurements.