Methods: Review of studies excluded from or included in the Cochrane systematic review of powered toothbrushes. Reports were compared against the criteria for inclusion in the review.
Results: 245 studies were excluded from the review. Many were ineligible for more than one reason. Sixty-five did not compare manual and powered toothbrushes. The other common reasons for exclusion were short duration (73 studies), not randomised controlled trials (RCTs)(28 studies), split-mouth designs (15 studies), inadequate reporting (13 studies) and combined interventions (9 studies).
Forty-two RCTs were included in the review. Four reports did not describe the mode of action of the brush. The generation of randomisation was adequate for 15 trials, inadequate for 2 and unclear for 25 trials. The concealment of allocation was adequate for 16 trials, unclear for 24 and inadequate for 2. The outcome assessor was adequately blinded in 38. Intention to treat analysis was not undertaken in 37. Thirty six trials reported plaque data using 10 different indices. Thirty-four trials at 1 to 3 months and 10 at longer than 3 months. Thirty-nine reported gingivitis (9 indices) at 1 to 3 months and 12 at greater than 3 months.
Conclusions: Authors of studies reporting toothbrush trials could consider the CONSORT statement and methods specific to toothbrush research could be standardised.