Abstract

There is inconclusive evidence about the relationship between toothbrush wear and plaque removal. This randomized cross-over clinical trial aimed to validate or invalidate non-inferiority in the plaque-removal efficacy of old vs. new toothbrushes in the hands of 7- and 8-year-old children. The lower limit for non-inferiority was set a priori as a difference in plaque score < 15%. Children (n = 101) brushed, in the first session, with either their 14-month-old toothbrush or a new one, and in the second session vice versa. The mean Quigley-Hein plaque score, before and after children brushed with old brushes, was 2.9 and 2.4, and with new brushes 2.8 and 2.1. The plaque score after they brushed with the new toothbrush was 10.9% lower (p < 0.001) than after they brushed with the old toothbrush. The confidence interval of 7.6%–13.9% was within the acceptance band (< 15%), and non-inferiority of old toothbrushes in the hands of these children was validated.