Plaque removal by a toothbrush results from a physical scrubbing of bristles on the tooth surface that removes adherent plaque bacteria. Because of the frequency of brush head motion, some power toothbrushes generally remove plaque more effectively than a manual brush. One power toothbrush, Philips Sonicare, claims also to remove plaque as a result of dynamic fluid activity. This effect has been shown in laboratory studies but clinical evidence is currently lacking. This review evaluated the data from well-controlled clinical studies carried out in normal subjects from a general population comparing the Sonicare toothbrushes with the Oral-B oscillating/rotating power toothbrush technology. It focuses on plaque removal from approximal surfaces where it is difficult for toothbrush bristles to reach, as it is here that any dynamic fluid effect should be most apparent. Results from the review found no evidence to support a greater efficacy for the Sonicare toothbrushes either generally or at approximal surfaces. Data revealed that the oscillating/rotating toothbrush was more effective than the Sonicare toothbrushes with respect to plaque removal. It is possible that factors associated with the clinical situation such as damping resulting from bristle contact with the tooth surface and the high viscosity of saliva and dentifrice may counteract dynamic fluid activity in vivo. This review indicates that dynamic fluid activity beyond the reach of bristles as demonstrated in the laboratory is yet unproven in the clinical situation.