J Funct Biomater. 2025 Mar 10;16(3):96. doi: 10.3390/jfb16030096.
ABSTRACT
This study assessed the changes in the mechanical and surface properties of the transition zone in multilayered translucent monolithic zirconia subjected to long-term hydrothermal aging. A total of 360 disk-shaped specimens (diameter: 15.0 mm; thickness: 1.2 mm) were prepared using conventional (3Y-TZP in LT; ZL, 4Y-TZP in MT; ZM) and multilayered translucent zirconia (5Y-TZP in MT Multi; ZT, 3Y/5Y-TZP in Prime; ZP) among IPS e.max ZirCAD blocks. Specimens were divided into three groups (n = 30) and aged in the autoclave at 134 °C under 0.2 MPa for 0 h (control group), 5 h (first aged group), and 10 h (second aged group). The mechanical and surface properties of the transition zone in the multilayered translucent zirconia were investigated, followed by statistical analysis (α = 0.05). Before and after aging, ZL (1102.64 ± 41.37 MPa) and ZP (1014.71 ± 139.86 MPa) showed the highest biaxial flexural strength (BFS); ZL showed the highest Weibull modulus (31.46) and characteristic strength (1121.63 MPa); and ZT exhibited the highest nanoindentation hardness (20.40 ± 1.80 GPa) and Young’s modulus (284.90 ± 20.07 GPa). After aging, ZL (116.75 ± 9.80 nm) exhibited the highest surface roughness (Ra); the monoclinic phase contents in ZL and ZP increased; and surface uplifts, microcracks, and irregular defects caused by phase transformation appeared on ZL and ZP surfaces. The 3Y/5Y-TZP transition zone exhibited flexural strength, Vickers hardness, phase distribution changes, and surface microstructure changes similar to those of 3Y-TZP before and after aging; however, the surface roughness was lower than that of 3Y-TZP and higher than those of 4Y-TZP and 5Y-TZP after aging. The mechanical and surface characteristics, excluding BFS and Vickers hardness, were influenced by the yttrium oxide content in each zone and the aging process.
PMID:40137375 | DOI:10.3390/jfb16030096
