Objectives: To determine whether brushing with a micronised amorphous precipitated abrasive silica grade (MS) can provide superior enamel surface finish relative to brushing with a conventional non-micronised silica grade (CS). Methods: Flat ground (800 grit) enamel specimens (n=8 per treatment) were brushed with slurries of CS (typical particle size distribution: d50=9.0μm; d90=30.6μm) or MS (typical particle size distribution: d50=3.4μm; d90=6.3μm), at 16.7% w/w silica in 0.5% w/w carboxymethylcellulose with 10% w/w glycerol. Brushing conditions were: 120 strokes/min for 10,000 double-strokes at 20°C, using a novel tooth-brushing simulator at 150g loading. This protocol was repeated using 1+3 w/w aqueous slurries of dentifrices containing 14% w/w CS with and without 4.2% w/w MS. Enamel surface roughness (Ra) was assessed before and after treatment (perpendicular to brush direction) using a Taylor-Hobson Talysurf Series 2 profilometer. Enamel surface gloss was assessed in gloss units (GU) before and after treatment with pastes using a Novo-Curve Small Area Glossmeter. Results: The data are summarised below:
|
Brushing Treatment |
Ra pre-brushing (µm, mean±s.d.) |
Ra post-brushing (µm, mean±s.d.) |
Gloss pre-brushing (GU, mean±s.d.) |
Gloss post-brushing (GU, mean±s.d.) |
|
MS |
0.214±0.022 |
0.098±0.026 |
- |
- |
|
CS |
0.229±0.036 |
0.170±0.051 |
- |
- |
|
CS+MS paste |
0.258±0.025 |
0.155±0.011 |
10.2±2.8 |
50.5±7.4 |
|
CS paste |
0.255±0.062 |
0.204±0.041 |
11.4±3.7 |
31.0±9.5 |