Effects of brushing duration on the efficacy of dental plaque removal: An in vitro study

This study was performed to evaluate the effects of varying brushing times on the dental plaque-removal efficacy of a power toothbrush to determine the optimal length of time required to brush the teeth.

A typodont with 32 teeth was divided into four quadrants and further divided into four zones each (two teeth per zone). Using a robotic arm, toothbrushing was performed over eight different brushing times (0, 60, 120, 180, 240, 300, 360, and 420 s) to remove the artificial plaque applied on the labial surface of the teeth in occlusion. Photographs were taken every 60 s from each zone of the typodont. The images obtained were processed using ImageJ software to measure the percentage of remaining plaque. Data were analysed with factorial ANOVA, least squares regression analysis, and post hoc Tukey tests.

Plaque removal significantly increased with brushing time across the brushing intervals studied (p < 0.05). Efficient plaque removal was achieved after 240 s of brushing. There was no significant difference in plaque accumulations between the maxillary and mandibular arch (p = 0.19) and the right and left areas after each time interval (p = 0.49).

Brushing duration is negatively correlated with the remaining plaque for a given toothbrush. Two minutes of brushing is not sufficient for significant plaque removal. Considering the limitations of this in vitro study, clinical studies are needed in order to change brushing recommendations to 240 s.