Dental crowns

The main advantages of a ceramic crown on zirconia, known as Nobel Procera, are :

Its biocompatibility and harmlessness in the oral cavity, in contrast to metal-ceramic crowns.
Its resistance: it is just as resistant, if not more so, than a metal-ceramic crown on gold, chrome-cobalt or any other alloy.
Aesthetics: because zirconia is white, it's best suited to support a ceramic dental crown.

Metal-free, all-ceramic dental prostheses have superior properties to metal ones, in terms of aesthetics, accounting and ecology.