ABSTRACT
The present work aims to study the effect of the brushing force on the mechanical wear of teeth during polishing. Teeth specimens were brushed using three different types of tooth pastes. Tooth paste A contained pumice of (30 – 40) μm particle size. Paste B contained 8 wt % of hydrated silica abrasive of (10 – 12) μm particle size. Type C paste is an abrasive-free paste. The abrasives used were standard Arizona sand (ACFTD) of 0 - 80 μm and (ACCTD) of 0 - 200 μm particle size. Alumina particles of (1 - 3 μm) and sand with particle sizes of (11 – 13 μm, 15 – 20 μm, 20 – 24 μm, 28 – 32 μm and 42 – 52 μm) were used to fabricate eight different pastes. The abrasives were added at a 10 wt. % concentration. The brushing speed used in the experiments was 150 strokes/min. The contact forces used were 3 and 5 N in the presence of water.
Based on the observations in the present work, it was found that the influence of the force on the abrasive wear of the teeth increased with increasing abrasive particle size. The most pronounced influence was displayed by paste A that contaminated by abrasive of 30 – 40 μm particle size. Paste B displayed slight wear increase with increasing the acting load. Besides, abrasives of wide range of particle sizes such as air cleaner fine test dust (0 – 80 μm) and air cleaner coarse test dust (0 – 200 μm) showed lower wear than paste A. In condition of adhesion, significant wear increase was observed for paste-free abrasives. When adding abrasive to tooth paste, it is recommended to avoid the abrasive particle sizes ranging from 20 - 50 μm to reduce the excessive abrasive wear occurred during polishing the teeth.