Effect of counterface roughness on abrasive wear of hydroxyapatite

The present study was undertaken to evaluate the effect of surface roughness of glass-infiltrated alumina on the abrasive wear of hydroxyapatite using a pin-on-disk tribometer. Hydroxyapatite was used as a model material to simulate tooth enamel. The wear tests were conducted in distilled water at room temperature using a constant sliding speed and three loads to model the normal occlusal contact conditions. The wear volume of polished hydroxyapatite pins increased by more than 20-fold as the average roughness of the alumina disks increased from 14 to 649 nm Ra. No measurable wear was detected on the alumina specimens. The wear surfaces were viewed in a scanning electron microscope (SEM) and were analyzed with X-ray dispersion spectroscopy to determine the extent of surface damage and the wear mechanisms. It is suggested that polished ceramic restorations will cause relatively low enamel wear, while increased roughness could severely abrade and damage the tooth enamel.