A clinical meta-analysis of oscillating brushes (power and sonic) found that only certain types remove significantly more plaque than a manual toothbrush. And even then, the amount of plaque removed was only up to 11% more than a manual brush.

Research on the Ionic toothbrush showed that it removes up to 48% more plaque than a manual toothbrush.  The Ionic toothbrush works on a different principle to other toothbrushes, making it extremely effective, even in hard-to-reach areas of the mouth