Dentifrice abrasivity. The use of laser light for determination of the abrasive properties of different silicas. An in vitro study.

The abrasive properties of five different silicon dioxides were investigated using laser reflexion. The substances were milled, amorphous silica gels of which four were commercially available dentifrice ingredients (Syloblanc) and one an experimental product. The abrasion process was carried out on acrylic plates in a brushing machine using two series of slurries of the substances, with and without sodium lauryl sulphate. Significant differences in abrasivity of the substances were observed. When sodium lauryl sulphate was included, the rate of abrasion decreased for the Syloblanc substances but increased for the experimental substance. The contrast was primarily explained by the capability of the different substances to form stable foams owing to their thickening properties. The investigation confirmed that silicon dioxides exhibit a wide range of abrasivity and proved that sodium lauryl sulphate influenced the abrasion process.