Comparative analysis on intaglio surface trueness, wear volume loss of antagonist, and fracture resistance of full-contour monolithic zirconia crown for single-visit dentistry under simulated mastication

Abstract

Purpose: This analysis aimed to evaluate the intaglio surface trueness, antagonist's wear volume loss, and fracture resistance of full-contour crowns of (Y, Nb)-stabilized fully-sintered zirconia (FSZ), 4 mol% or 5 mol% yttria-stabilized partially sintered zirconia (4YZ or 5YZ) with high-speed sintering.

Materials and methods: A total of 42 zirconia crowns were separated into three groups: FSZ, 4YZ, and 5YZ (n = 14). The intaglio surface trueness of the crowns was evaluated at the inner surface, occlusal, margin, and axial areas and reported as root-mean-square, positive and negative average deviation. Half of the specimens were aged for 120,000 cycles in the chewing simulator, and the wear volume loss of antagonist was measured. Before and after chewing, the fracture load was measured for each group. The trueness values were analyzed with Welch's ANOVA, and the wear volume loss with the Kruskal-Wallis tests. Effect of the zirconia type and aging on fracture resistance of crowns was tested using two-way ANOVA.

Results: The intaglio surface trueness measured at four different areas of the crown was less than 50 µm, regardless of the type of zirconia. No significant P in wear volume loss of antagonists were detected among the groups (P > .05). Both the type of zirconia and aging showed statistically significant effects on fracture resistance (P < .05).

Conclusion: The full-contour crowns of FSZ as well as 4YZ or 5YZ with high-speed sintering were clinically acceptable, in terms of intaglio surface trueness, antagonist's wear volume loss, and fracture resistance after simulated mastication.

Keywords: Fracture resistance; Fully-sintered zirconia; High-speed sintering; Intaglio surface trueness; Wear volume loss.

Fig. 1. Intaglio surface trueness measurements (µm, root-mean-square) of three zirconia groups measured in four different areas of inspection. (A) Margin, (B) Axial area, (C) Occlusal area, (D) Inner area. Statistically significant difference (P <. 05) was marked with asterisk (^*). FSZ, Fully-sintered (Y,Nb)-TZP group; 4YZ, Partially sintered 4Y-PSZ group; 5YZ, Partially sintered 5Y-PSZ group.

Fig. 2. Representative color deviation maps of intaglio trueness of 3 zirconia crown groups (positive deviation, yellow to red, negative deviation, cyan to blue, deviation below 50 µm, green). (A) FSZ, Fully-sintered (Y,Nb)-TZP group; (B) 4YZ, Partially sintered 4Y-PSZ group; (C) 5YZ, partially sintered 5Y-PSZ group.

Fig. 3. Fracture load (N) of three zirconia groups before and after artificial aging.

FSZ, Fully-sintered (Y,Nb)-TZP group; 4YZ, Partially sintered 4Y-PSZ group; 5YZ, Partially sintered 5Y-PSZ group. ^*Statistically significant difference (P < .05).