Antagonist wear of three CAD/CAM anatomic contour zirconia ceramics.

Statement Of Problem: Little clinical information exists on the antagonist wear of anatomic contour zirconia crowns.

Purpose: The purpose of this in vitro study was to evaluate the 2-body wear of antagonists for 3 computer-aided design and computer-aided manufacturing (CAD/CAM) anatomic contour zirconia ceramics and veneering porcelain when opposing natural human enamel.

Material And Methods: Zirkonzahn Y-TZP (polished zirconia, zirconia with staining, zirconia with staining and glazing), Acucera Y-TZP, Wieland Y-TZP, and Noritake feldspathic ceramic were tested (6 groups). Eight disk-shaped specimens 15 mm in diameter and 5 mm thick were prepared for each group. Forty-eight specimens were fabricated for a wear test against maxillary premolars without caries or previous restorations with 240 000 masticatory cycles in a masticatory simulator. Before the experiment, the surface roughness of each ceramic was measured with a nanosurface 3-dimensional (3D) optical profiler. The surface of the specimens was observed at 50× and 1000× magnification with a field emission scanning electron microscope (FE-SEM) before and after the experiment. The data obtained were statistically analyzed by 1-way ANOVA and the Tukey test for post hoc analysis (α=.05).

Results: The SEM observations of each group revealed fine bubbles and porous surfaces in the Noritake feldspathic ceramic group, whereas the polished Zirkonzahn Y-TZP group, Acucera Y-TZP group, and Wieland Y-TZP group had smooth surfaces. The surface roughness of Zirkonzahn Y-TZP after staining and glazing was significantly greater than that of any other groups (P<.01). The tooth opposing the polished Zirkonzahn Y-TZP group demonstrated the least wear (1.11 ± 0.51 mm³), while Zirkonzahn Y-TZP with staining and glazing produced the greatest enamel wear (3.07 ± 0.98 mm³) among the zirconia groups. The Noritake feldspathic ceramic group showed significantly more antagonistic tooth wear than other groups (P<.05).

Conclusions: The antagonist wear of 3 CAD/CAM anatomic contour zirconia ceramics was significantly less than the Noritake veneering ceramic because the surface character of Y-TZP is relatively uniform and homogeneous. Zirkonzahn Y-TZP with staining and glazing was significantly more abrasive than the other zirconia specimens tested. However, it was less abrasive than the Noritake veneering ceramic.