Statistical analysis
Brushing force
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For each volunteer brushing force of each sextant and each site was averaged for the mean
brushing force. As values might be altered by moving the toothbrush from one sextant or site
to the other, the values of the first and last 5 s of the 20 s brushing interval were discarded.
Based on the fact that the brushing force was measured with a frequency of 50
measurements/s, a total of 500 single values were averaged to the mean brushing force of
each interval.
Statistical analysis was performed by repeated measures ANOVA and Bonferroni post-hoc
tests (p < 0.05) to analyse differences between the toothbrushes, between the brushing
forces before and after instruction of the brushing technique, and between different sited and
sextants.