A Cochrane review (abstract , review ) included 51 studies with a total of 4624 participants. Brushes with a rotation oscillation action removed plaque and reduced gingivitis more effectively than manual brushes in the short term and reduced gingivitis scores in studies over 3 months. For plaque at 1 to 3 months the SMD was –0.50 (95% CI –0.70 to –0.31), for gingivitis SMD –0.43 (95% CI –0.60 to –0.25) representing an 11% difference on the Quigley Hein plaque index and a 6% reduction on the Löe and Silness gingival index. At over 3 months the SMD for plaque was –0.47 (95% CI –0.82 to 0.11) and for gingivitis was –0.21 (–0.31 to –0.12). There was heterogeneity between the trials for the short-term follow up. Sensitivity analyses revealed the results to be robust when selecting trials of high quality. There was no evidence of any publication bias.