Effect of bristle stiffness of manual toothbrushes on normal and demineralized human enamelAn in vitro profilometric study

ObjectiveTo compare the brushing abrasion carried out by manual toothbrushes with different bristle types (hard and soft) on normal and demineralized human enamel. Materials and MethodsThirty enamel blocks (N=30) were prepared and were randomly divided into three main groups: A, teeth kept in artificial saliva with no brushing (control, n=2); B, teeth brushed with toothbrushes with hard bristles (n=14); and C, teeth brushed with toothbrushes with soft bristles (n=14). Seven teeth belonging to groups B and C were brushed normally, and the remaining seven were demineralized before brushing experiments with 6 wt.% citric acid (pH = 2.2) for 5 minutes. The brushing experiments were carried out twice a day for 2 mins for 7days inside a toothbrush simulation machine. The changes in the surface of enamel (prebrushing and post-brushing) were evaluated using non-contact profilometry. The results were analysed statistically using Kruskal-Wallis test and the Wilcoxon signed rank test. ResultsFor both normal and demineralized enamel, toothbrushes with soft bristles caused more abrasion. The results revealed significant differences (P=.055) in the surface roughness values between the four groups prebrushing. Within each group, the prebrushing and post-brushing surface roughness value differences were all statistically significant (P<.05). ConclusionsThe results demonstrate that soft bristles caused more abrasion as compared with the hard bristles. These results could have an impact on the toothbrush recommendations for patients.