Dental crowns made entirely of porcelain do not contain an internal framework, so they are much more vulnerable than crowns with a zirconium framework.

Metal-ceramic crowns build on an inner metal framework,thus their light transparency decreases, also may gray over time the edges of the teeth.

Circonia crowns have a circonium framework in the shade of the teeth on which veneering porcelain can be obtained, thus enabling the production of durable, solid and esthetic dentures.