Solid zirconia or "monolithic zirconia" is naturally translucent and opalescent, but is generally recommended for posterior crowns due to this property. This material is also especially suitable for people who may grind their teeth because of its high strength. Only minimal clearance is required and there is little wear on the associated teeth. Solid zirconia is also very effective for masking highly discolored dental preparations, especially those that have been blackened due to previous dental treatments, such as post and core or restorative dental implants.
Layered zirconia is more translucent and milky white, but unlike solid zirconia, it is especially suitable for anterior crowns. Although usually used for anterior crowns, layered zirconia can also be used for posterior crowns if there is sufficient space with other teeth. The best aesthetics can be achieved if done skillfully. Solid and layered zirconia crowns have comparable strength and consistency to traditional PFM restorations, yet they offer superior aesthetic results.