Questions & Answers on Zirconia
Nov 26, 2018| 
Q: Does zirconia ceramic degrade in strength intraorally in 5-10 years?
A: Yes, all-ceramic materials degrade in strength over time - some more than others. Zirconia ceramic has an initial flexural strength of over 1200 MPa, so even if it degrades 5-10% or more, it is still significantly stronger than other ceramics.
Q: Does it takes longer to remove a zirconia crown with a bur compared to a PFM crown?
A: Fine diamond burs can cut thru a zirconia crown just as fast as a PFM crown.
Q: Does shading or coloring zirconia ceramic reduce the strength as compared to the uncolored zircona?
A: Weakening of colored zirconia ceramic copings has not been observed.
Q: Is the fit of crowns and bridges based on zirconia copings as good as that of PFM crowns and bridges?
A: Yes, the marginal fit of crowns and bridges fabricated from zirconia copings can be as good or better than PFM crowns and bridges.
Q: Is the fit of a zirconia coping important since the zirconia ceramic is so strong?
A: The thicker the cement the weaker the all-ceramic restoration. Cements are not as rigid as zirconia ceramic, so a thicker cement layer will cause more flexural deformation of a ceramic core, increasing the potential for fracture.
Q: Does silane treatment improve the bond strength of a resin cement to a zirconia coping?
A: No, but the use of Rocatec/Cojet (3M ESPE) does. Silica particles are embedded into the surface of zirconia and then silanated. This treatment can increase the bond strength of a resin cement to a zirconia coping.