Impact of brushing force on abrasion of acid-softened and sound enamel.
OBJECTIVE
The study aimed to analyse the effects of different brushing loads on abrasion of acid-softened and sound enamel surfaces.


METHODS
Sound and acid-softened surfaces of each 10 human enamel samples were submitted to brushing abrasion in an automatic brushing machine at 1.5 N (A), 2.5 N (B), 3.5 N (C) or 4.5 N (D) brushing load. Prior to abrasion, demineralisation of half of each enamel surface was performed by storage in hydrochloric acid (pH 2.0) for 60s. Brushing was carried out (1000 strokes) using a manual toothbrush and toothpaste slurry in a ratio of 1:3. Enamel loss was measured after 10, 20, 50, 100, 150, 200, 250, 300, 350 and 1000 brushing strokes (BS). Pre- and post-brushing values of Knoop indentation length (5 indentations each sample) were measured and mean enamel loss was calculated from the change in indentation depth. Within- and between-group comparisons were performed by ANOVA and t-test followed by Bonferroni-correction.


RESULTS
Enamel loss of acid-softened surfaces was significantly influenced by the brushing load applied and was mostly significantly higher in group D (10-1000 BS: 225-462 nm) compared to A (10-1000 BS: 164-384), B (10-1000 BS: 175-370 nm) and C (10-1000 BS: 191-396 nm). Abrasion of acid-softened enamel was fourfold higher compared to sound surfaces. Sound enamel was significantly influenced by the brushing force at 20-200 brushing strokes only, but revealed no significant differences between groups A-D.


CONCLUSIONS
Brushing load influences abrasion of briefly eroded enamel, but might be of minor importance for abrasion of sound enamel surfaces.
Wiegand
A
A
Clinic for Preventive Dentistry, Periodontology and Cariology, University of Zürich, Plattenstrasse 11, CH-8032 Zürich, Switzerland. annette.wiegand@zzmk.unizh.ch
Köwing
L
L
Attin
T
T
D000143:Acids; D000704:Analysis of Variance; D001696:Biomechanical Phenomena; D016022:Case-Control Studies; D003743:Dental Enamel / Q000187:drug effects / Q000473:pathology*; D006801:Humans; D014072:Tooth Abrasion / Q000473:pathology*; D017001:Tooth Demineralization / Q000473:pathology*; D014099:Toothbrushing / Q000009:adverse effects*; D014100:Toothpastes
D000143:Acids; D014100:Toothpastes