Impact of hydrothermal aging on the light transmittance and flexural strength of colored yttria-stabilized zirconia materials of different formulations

Lumkemann, Nina und Stawarczyk, Bogna (2021): Impact of hydrothermal aging on the light transmittance and flexural strength of colored yttria-stabilized zirconia materials of different formulations. In: Journal of Prosthetic Dentistry, Bd. 125, Nr. 3: S. 518-526

Abstract

Statement of problem. Yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) materials of different formulations (3Y-TZP, 4Y-TZP, and 5Y-TZP) can be colored by using color liquids. However, practically and clinically relevant factors such as modifications of sintering protocols and hydrothermal aging might affect the extent of light transmittance and flexural strength of zirconia materials of different formulations;studies on these outcomes, however, are lacking. Purpose. The purpose of this in vitro study was to test the impact of hydrothermal aging on the light transmittance and flexural strength of colored zirconia materials compared with a lithium-disilicate (LiSi2) ceramic. Material and methods. A total of 210 specimens were prepared from 3Y-TZP(0.25) (n=30), 3Y-TZP(0.05) (n=30), 5Y-TZP (n=30), 4Y-TZP (n=60), (pre)4Y-TZP (preshaded, n=30), and LiSi2 (n=30). All specimens, except for (pre)4Y-TZP and LiSi2, were manually colored, predried, and either conventionally sintered at 1450 degrees C (3Y-TZP(0.25), 3Y-TZP(0.05), 5Y-TZP, and half of 4Y-TZP) or high-speed sintered at 1580 degrees C (other half of 4Y-TZP and (pre)4Y-TZP). Light transmittance was measured initially and after 2, 5, 10, 20, 40, and 160 hours of hydrothermal aging (134 degrees C, 0.2 MPa). Biaxial flexural strength was tested initially and after 160 hours of hydrothermal aging (n=15). The Kolmogorov-Smirnov test, multivariate analysis, and 1-way ANOVA with the Tukey HSD post hoc test, the t test, and linear mixed models were calculated (alpha=.05). Results. LiSi2 showed the highest translucency, followed by 5Y-TZP, 4Y-TZP, (pre)4Y-TZP(speed), 3Y-TZP0.05, and 3Y-TZP(0.25). 4Y-TZP(speed) was most opaque and matte. The decrease in translucency related to aging hours was higher for LiS2 and conventional sintered zirconia materials than for 4Y-TZP(speed) and (pre)4Y-TZPspeed. Initially, 3Y-TZP(0.25) had the highest flexural strength, followed by 3Y-TZP(0.05), 4Y-TZP, and (pre)4Y-TZP(speed). (pre)4Y-TZP(speed) was comparable with 4Y-TZP(speed) but significantly higher than 5Y-TZP. LiSi2 had the lowest biaxial flexural strength. Hydrothermal aging increased biaxial flexural strength for 3Y-TZP(0.25) and 3Y-TZP(0.05) (P<.001) but decreased it for 5Y-TZP (P=.005) and (pre)4Y-TZP(speed) (P<.001). After aging, 4Y-TZPspeed showed comparable values of flexural strength with 4Y-TZP (P=.06) and higher values than (pre)4Y-TZPspeed after aging (P=.019). Conclusions. Manually colored, conventionally sintered 4Y-TZP was resistant to hydrothermal aging regarding flexural strength. High-speed sintering inhibited color development for manually colored 4Y-TZP but did not affect the resistance to hydrothermal aging. The findings were reversed for industrially preshaded 4Y-TZP.

• Dokumententyp: Zeitschriftenartikel
• Fakultät: Medizin
• Themengebiete: 600 Technik, Medizin, angewandte Wissenschaften > 610 Medizin und Gesundheit
• ISSN: 0022-3913
• Sprache: Englisch