Surface, Microstructural, and Mechanical Characterization of Prefabricated Pediatric Zirconia Crowns

The purpose of this study was to characterize the surface roughness, the microstructure, and mechanical properties of four prefabricated zirconia pediatric crowns. Ten prefabricated crowns from four different manufacturers (Cheng Crowns Zirconia), (EZCrowns), (NuSmile ZR), and (Zirconia Pediatric Crowns) were included in this study. The surface roughness parameters (Sa, Sq, Sz, Sc, and Sv) of all samples were studied by optical profilometry and then the microstructure was studied by Raman spectroscopy. Then, all samples were embedded in epoxy resin and after metallographic polishing, the Martens hardness (HM), indentation modulus (E(IT)), elastic index (η(IT)), Vickers hardness (HV), and fracture toughness (K(IC)) were identified by the Instrumented Indentation Testing (IIT). All data were statistically analyzed by a one-way ANOVA and a Tukey multiple comparison test at α = 0.05. Only the tetragonal phase of zirconia for all materials tested was identified after Raman analysis. However, statistically significant differences were found among the surface roughness parameters, HV and K(IC), while no differences were allocated for HΜ, E(IT), and η(ΙΤ). Although the materials tested shared a similar microstructure, significant differences in surface roughness parameters HV and K(IC) were identified and, thus, differences in their clinical performance were anticipated.