The effect of sintering process on zirconia's optical and physical properties Public Deposited

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Last Modified
  • March 22, 2019
Creator
  • Swann, Lida
    • Affiliation: School of Dentistry, Department of Prosthodontics
Abstract
  • Zirconia restorations present an alternative dental restorative option with an average flexural strength of 1000 MPA. One of the challenges of this material is the decreased translucency when compared with less strong ceramic materials like feldespatic porcelain or lithium disilicate. A potential solution to this challenge is to the increase of sintering temperature and or increase holding times. The present study evaluated the effect of different sintering temperatures and holding times on contrast ratio as a measure of translucency, and evaluated if any temperatures or holding times could have a negative effect on materials strength. We also looked at the effect of cyclic loading vs conventional load to failure testing. One hundred and twenty (120) milled zirconia disks with .2mm thickness and 14mm diameter were sintered . Temperatures vary in 50 degree increments from 1450 to1600 F. Each of those temperatures was held for different times including 1h, 2h, 3h. The ziconia disks used were pure white Zenostar, 10 disks were obtained to test each variable. Contrast ration was measured on a spectophotometer for all specimens. 60 specimens (5 per group) were subjected to mechanical cyclic loading under water at a load of 100N for 100,000 cycles at a frequency of 1.5Hz. After fatigue loading samples and control group were tested on an Instron machine until catastrophic failure occurred. Under the conditions measured, increasing temperature and / or holding time did not alter translucency or significantly affected physical properties.
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  • In Copyright
Advisor
  • Cooper, Lyndon F.
Degree
  • Master of Science
Graduation year
  • 2014
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