The power toothbrushes caused significantly higher dentin abrasion compared to the manual toothbrushes using the same brushing force and time. The mean (± standard deviation, and 95% confidence level 95%CI) surface loss was 21.03 (±1.26, 95%CI = 20.41–21.66) μm for the sonic toothbrush, 15.71 (±0.85, 95%CI = 15.28–16.13) μm for the oscillating-rotating toothbrush, 6.13 (±1.24, 95%CI = 5.51–6.75) μm for the flat trim manual toothbrush, and 2.50 (±0.43, 95%CI = 2.28–2.71) μm for the rippled-shaped manual toothbrush. Highest dentin abrasion was measured for sonic toothbrush and lowest for the rippled-shaped manual
Seventy-two extracted human molars were used to generate dentin specimens
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Specimens were randomly allocated to four groups (
Fig 2). 18 specimens were assigned to each toothbrush. The total brushing strokes were calculated to be equivalent to 8.5 years of brushing, based on a brushing time of 120 seconds twice-daily of all teeth [
15]. Based on this estimation, the maximum contact time for one tooth surface per day is 5 seconds [
16]. The total brushing time was calculated to be 260 min. The brush head should be replaced after 45 days (a typical time period to replace the brush). This represents 270 minutes of cumulative use for 28 teeth (72 surfaces) with 5 s brushing per day.