Fig. 4
The types and replacement frequency of toothbrushes of dental students and non-dental students. a, b Before the course, most students in both groups preferred electric toothbrushes to manual toothbrushes. However, the actual usage of electric toothbrushes was low. After the course, more dental students thought electric toothbrushes were better. c Soft-bristled toothbrushes were favoured by more students after the course. d There was no obvious difference in the frequency of changing toothbrushes between the two groups (P > 0.05) (Wilcoxon signed-rank test; ****, P = 0.000; ***, P = 0.001; **, P = 0.01; *, P < 0.05)