OBJECTIVES: To evaluate different surface treatment effects on physical and mechanical properties of various types of zirconia subjected to hydrothermal aging.
MATERIALS AND METHODS: This is an in vitro study on four different types of monolithic zirconia material: VITA-Zahnfabrik VITA-YZ T, VITA-YZ HT, VITA-YZ ST, VITA-YZ XT. A total of 240-disc specimens were prepared by core-drilling and sectioned with a diamond blade. Specimens were sintered according to the manufacturer’s recommendations. Half of the specimens in each group were then glazed and subjected to low temperature degradation. Three different locations were evaluated for surface roughness each group of the four different materials by using Mitutoyo SJ-201 contact profilometer with a 5μm diamond stylus tip. A Bruker D2 Phaser diffractometer was used for X-ray diffraction (XRD) measurements. Crystallographic phase identification and analysis were performed through Rietveld refinements on XRD raw data. Biaxial flexural strength was determined and the fractography was analyzed. Descriptive data such as surface roughness, crystallographic phase contents, and flexural strength were indicated as mean and standard deviation (SD). Statistical analysis was performed using multi-way ANOVA and linear regression model followed by the post hoc Tukey tests.
RESULTS: All VITA YZ zirconia non-glazed control specimens showed higher means of biaxial flexural strength values compared to glazed specimens. VITA YZ HT specimens showed the highest mean of biaxial flexural strength in this study with values of 781 – 1305 MPa. On the other hand, VITA YZ XT expressed the lowest mean of biaxial flexural strength values of 466 – 972 MPa. The surface roughness of monolithic VITA YZ materials was statistically significantly low for the various zirconia materials. Aging of various zirconia materials showed statistically significant effect of aging on glazed specimens was not statistically significant. There was no significant difference in the tetragonal phase content of all VITA YZ materials (p > 0.05). There was significant difference in the cubic phase content of all VITA YZ materials (p < 0.05). On the other hand, aging process as well as the interaction between the material type and aging had no significant effect on the cubic phase content of YZ specimens (p > 0.05). There was significant difference in the rhombohedral phase of all VITA YZ materials as well as aging process (p < 0.05).
CONCLUSIONS: Biaxial flexural strength was significantly affected by glazing, type of material, treatment protocol. Biaxial flexural strength was significantly affected by the interaction between type of material and treatment protocol, glazing and type of material.
The VITA YZ ST control had the lowest surface roughness among all the groups. The difference was statistically significant.
The type of material, aging, and the interaction effect between the material and aging were significantly different for XRD in non-glazed material.
The VITA YZ T showed the lowest mean of yttrium oxide (Y2O3) molecular fraction. On the other hand, YZ XT showed the highest mean of Yttrium oxide (Y2O3) molecular fraction.
| Identifer | oai:union.ndltd.org:bu.edu/oai:open.bu.edu:2144/44992 |
| Date | 11 August 2022 |
| Creators | Suleiman, Muad Mohamed A. |
| Contributors | Giordano, Russell A. |
| Source Sets | Boston University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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