Zirconia Dental Implants Crowns , Complete Dental Implants FDA
Abutment Material -ZirconiaPhysical properties
ZrO 2 adopts a monoclinic crystal structure at roomtemperature and transitions to tetrgonal and cubicstructures at higher temperatures.
The volume expansion caused by the cubic to tetragonaltomonoclinictransformation induces large stresses, and these stresses
cause ZrO 2 to crack upon cooling from high temperatures. When the ziconia is blended with some otheroxides such as yttrium oxide (Y 2 O 3 , yttria), the tetrago-
nal and/or cubic phases are stabilized.
Even though different brands of zirconia can be chemicallysimilar they are not necessarily the same.
Different brandsof zirconia ceramic are chemically similar, but onceprocessed it can exhibit different mechanical andoptical characteristics.
When working with zirconiathere are differences in machinability (e.g. wet millingand dry milling) and in sintering (e.g. sintering temperature for Vita YZ-Cube is 1530C; for Lavaframeworks is 1500C; for Cercon is 1350C).
What is different? In principle, there is pre-sinteredzirconia and HIP zirconia available on the market.
The pre-sintered zirconia is milled and the materialstill has a soft, chalk-like consistency.
For full density, it is sintered again after milling.HIP material is milled in the fully sintered state.
Note that the processing parametersfor pre-sintered zirconia affect its performance