Toothpaste products amorphous silica

Precipitated silica (silica P) abrasive SiOj have been introduced in toothpaste formulation in the 1970s. They are synthetic, noncrystaUine, or amorphous silica. They represent -80% of the world production of synthetic amorphous silica. Variation in the particle size allows the control of the abrasivity and the thickness of the product. Amorphous silica is obtained by reaction of a sodium silicate solution at pH >7 with an add such as H2SO4 or HCl, according to the following reaction ... 

Tripoli. Tripoli [1317-95-9] is a fine grained, porous, decomposed siliceous rock produced mainly in Arkansas, Illinois, and Oklahoma. It is widely used for polisliing and buffing metals, lacquer finishing, and plated products. Since tripoli particles are rounded, not sharp, it has a mild abrasive action particularly suited for polisliing. Tripoli is also used in toothpastes, in jewelry polisliing, and as filler in paints, plastics, and rubber. Rottenstone and amorphous silica are similar to tripoli and find the same uses. In 1987 the abrasive use of tripoli in the United States totaled 26.6 million tons and was valued at about 3.1 million however, the portion used as a filler totaled 71.1 million tons and had a value of almost 10 million (4). 

Virtually all dentifrice formulations contain abrasive particles, typically composed of amorphous silica, calcium carbonate, alumina or calcium phosphate. The mechanism by which the toothbrush and dentifrice interact to clean the teeth is one of abrasive cleaning. Toothpaste manufacturers thus aim to provide formulations with effective cleaning power, whilst minimising any wear to the underlying substrate. However, in such a system it is inevitable that some degree of abrasivity will be present, as toothpastes without abrasive particles are unable to prevent the build-up of extrinsic stain [12], It is, therefore, important to understand any abrasion a dentifrice product may cause to the hard tissues in the mouth. 

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