[The abrasion resistance of plastic teeth--an in-vitro study]

Resistance against abrasion of premolar plastic teeth on their chewing surfaces was determined using an in vitro test method which approximately simulated oral conditions, as well as contact between antagonists, chewing pressure, biting pressure and chewing motion. The humpy surface of commercially manufactured teeth was levelled by grinding, using the abrasion test machine itself, which resulted in two little plain surfaces. After measuring the size of these surfaces, wear due to abrasion was determined by loss of weight. The commercial products showed different resistances against abrasion, the teeth of Dens-Nobilis and Vitapan, which contain amorphous silica, appeared to be more resistant against abrasion than IPN (Artiplus) and PMMA (Keracryl-7, Planustar, SR-Orthotyp-PE) teeth. Unexpectedly, IPN teeth did not show a higher resistance against abrasion than the PMMA teeth, which were tested in this investigation. Only SR-Orthotyp-PE were significantly worse. Under the prevailing test conditions SR-Orthosit-PE teeth are very little resistant against abrasion, although they contain amorphous silica. Investigations with a raster electron microscope revealed that they are too brittle.