Abstract
Objectives: The aim of this study was to compare composition, microstructure, and mechanical strength of current multilayer zirconia blanks.Methods: Bar shaped specimens were made from several layers of multilayer zirconia blanks (Cercon ht ML, Dentsply Sirona, US; Katana Zirconia YML, Kuraray, J;SHOFU Disk ZR Lucent Supra, Shofu, J; priti multidisc ZrO2 Multi Translucent, Pritidenta, D; IPS ...
Abstract
Objectives: The aim of this study was to compare composition, microstructure, and mechanical strength of current multilayer zirconia blanks.Methods: Bar shaped specimens were made from several layers of multilayer zirconia blanks (Cercon ht ML, Dentsply Sirona, US; Katana Zirconia YML, Kuraray, J;SHOFU Disk ZR Lucent Supra, Shofu, J; priti multidisc ZrO2 Multi Translucent, Pritidenta, D; IPS e.max ZirCAD Prime, Ivoclar Vivadent, FL). Flexural strength was determined in a three-point bending test on extra-thin bars. X-ray diffraction (XRD) with Rietveld refinement was used to assess crystal structure and scanning electron microscopy (SEM) imaging to visualize the micro-structure of each material and layer.Results: Mean flexural strength varied between 467.5 +/- 97.5 MPa (top layer, IPS e.max ZirCAD Prime) and 898.0 +/- 188.5 MPa (bottom layer, Cercon ht ML) with significant (p <= 0.055) differences between the in-dividual layers. XRD indicated 5Y-TZP for enamel-layers, 3Y-TZP for dentine-layers, individual mixtures of 3Y-TZP, 4Y-TZP, or 5 Y-TZP for intermediate layers. SEM analysis showed grain sizes between approx. 0.15 and 4 mu m. Grain size tended to decrease from top to bottom layers.Significance: The investigated blanks differ predominantly in the intermediate layers. In addition to di-mensioning of restorations, the milling position in the blanks must also be taken into account when using multilayer zirconia as restorative material.
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