Available online 10 March 2023
Author links open overlay panel, , , , AbstractObjectivesThe aim of this study was to compare composition, microstructure, and mechanical strength of current multilayer zirconia blanks.
MethodsBar 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 microstructure of each material and layer.
ResultsMean 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 individual 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 µm. Grain size tended to decrease from top to bottom layers.
SignificanceThe investigated blanks differ predominantly in the intermediate layers. In addition to dimensioning of restorations, the milling position in the blanks must also be taken into account when using multilayer zirconia as restorative material.
KeywordsMultilayer
Zirconia
3Y-TZP
4Y-TZP
5Y-TZP
XRD
X-ray diffraction
Flexural strength
SEM
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