Journal of Dental Research, Vol 78, 713-719, Copyright © 1999 by International & American Associations for Dental Research Online Journals
The influence of antagonist standardization on wear
I. Krejci, P. Albert and F. Lutz
University of Geneva, School of Dentistry, Department of Cariology, Endodontology and Pediatric Dentistry, Switzerland.
For differences among materials to be easily detected, low variation in in
vitro wear tests is desirable. The working hypothesis of this paper was
that antagonists standardized for shape and size and according to materials
would show mean values similar to those found in natural, non-standardized
cusps, and that standardization would lead to a reduction in mean
variation. First, the shapes and sizes of palatal cusps of non-erupted
human upper third molars were measured. The cusp cupola was best described
by the formula y = 0.001 x2 and was symmetrical around the axis of
rotation. Up to 200 microm of the y-axis, this parabola corresponded best
to a ball radius of 0.6 mm. Based on this information, standardized
antagonists were fabricated from both human enamel and steatite. Wear in
the occlusal contact area and the wear of opposing conventional ceramic and
fine hybrid composite, respectively, were quantified in a computerized
chewing simulator. As a control, natural human enamel cusps were used.
Standardization of enamel cusps did not reduce the variation of the
resulting wear compared with that of non-standardized enamel antagonists.
Furthermore, standardization led to significantly different results both in
the antagonists and in the opposing restorative materials. Thus, natural
enamel antagonists are preferable for the simulation of wear in the
occlusal contact area.
