Mechanical properties of aged yttria-stabilized tetragonal zirconia polycrystal after abrasion with different aluminum oxide particles

Abstract

Statement of problemA consensus on the benefits of airborne-particle abrasion of zirconia with alumina particles of different sizes is still lacking. Larger particle size may improve micromechanical retention but may generate deep microcracks on the zirconia surface. PurposeThe purpose of this in vitro study was to evaluate the effect of different size of Al2O3 particles used for surface abrasion on the mechanical properties of yttria-stabilized tetragonal zirconia polycrystal (Y-TZP). Material and methodsSixty Y-TZP specimens were divided into 6 groups according to the treatment: control (without treatment) or airborne-particle abrasion with Al2O3 particles (45 μm or 150 μm). Half the specimens were stored for 24 hours in water while the other half was exposed to 1.5×106 mechanical cycles before flexural strength analysis at 1 mm/min crosshead speed. Specimens were also characterized by micro-Raman spectroscopy and X-ray diffraction (XRD) to evaluate the crystalline composition. The data were subjected to 2-way ANOVA and Tukey HSD test (α=.05). ResultsAirborne-particle abrasion with alumina (P=.030) and mechanical fatigue (P<.001) had a significant effect on flexural strength. Specimens abraded with 45-μm Al2O3 particles (847 ±204 MPa) presented higher flexural strength than those of the control group (670 ±210 MPa). The size of the alumina particles was not significant for flexural strength. Flexural resistance (664 MPa) significantly decreased after mechanical fatigue. All groups showed only the tetragonal phase on the micro-Raman spectra, which was confirmed by XRD. ConclusionsAirborne-particle abrasion with smaller Al2O3 particles increased the flexural strength on Y-TZP without causing phase transformation. However, flexural strength was decreased after mechanical fatigue.