A two-body frictional wear test.

Enamel abraders used in two-body wear tests suffer the disadvantage that standardization is difficult or impossible to obtain. The aim of this study was to test whether steatite (a ceramic material with a Vickers Hardness similar to that of enamel) could be used as a satisfactory human enamel analogue. The friction and wear characteristics of 'spherical' abraders made from these two materials against composite and amalgam specimens were therefore compared. A two-body wear test for restorative materials was devised which could be carried out in a Universal Testing Machine and which allowed for continuous monitoring of the frictional forces during wear. The results showed that steatite and enamel abraders produced similar coefficients of friction (correlation coefficient, r = 0.98). A linear relationship was found between depth (and volume) of wear and number of cycles (r = 0.98 to 0.99). Wear rate was not affected by the increase in abrader facet area. The wear rate against the steatite abrader was slightly greater than that against enamel, but the two abraders were reasonably correlated (r = 0.94). Friction and wear were correlated for the steatite abrader (P < 0.05, r = 0.88) but not the enamel abrader. The hybrid composites had a high wear rate and wore both the abraders more than did the microfilled composites or amalgam. These findings suggest that steatite is a suitable substitute for enamel in this type of test.