Colored Zirconia Green Body Restoration

Abstract

A dental block for producing a dental prosthesis comprises a green body including zirconia and having a chemical composition including increasing amounts of yttria through a thickness of the green body. The green body is substantially opaque with a substantially consistent optical characteristic of non-translucency with respect to visible light across the thickness, and is subsequently millable and sinterable to form the dental prosthesis with an optical characteristic of increasing translucency through a thickness of the dental prosthesis.

1 . A colored zirconia green body restoration, comprising:
 a) greater than 99 wt % of zirconia, yttria and hafnia;   b) between 6.0 wt % and 20 wt % of yttria based on a total weight percent of the colored zirconia green body restoration; and   c) zirconia oxide particles having a particle size between 0.1 to 1.0 microns; and   d) the colored zirconia green body restoration being subsequently finally sinterable to produce a translucent zirconia sintered body having a total light transmittance of at least 35% and less than 53% to light with a wavelength at least at a point between 400 nm and 600 nm, and at least 51% and less than 57% to light with a wavelength at least at a point between 600 nm and 800 nm, at a thickness of 0.6 mm.   
     
     
         2 . The colored zirconia green body restoration in accordance with  claim 1 , wherein the amount of yttria is increased incrementally from a lower layer to an upper layer. 
     
     
         3 . The colored zirconia green body restoration in accordance with  claim 1 , further comprising:
 multiple different layers each having a different chemical composition between adjacent layers, the different chemical composition including different amounts of yttria between the adjacent layers.   
     
     
         4 . The colored zirconia green body restoration in accordance with  claim 3 , wherein the multiple different layers have different thicknesses with respect to one another with a lower layer having a thickness between 2-5 mm and an upper layer having a thickness between 0.5-2 mm. 
     
     
         5 . The colored zirconia green body restoration in accordance with  claim 1 , wherein the final sintering is in air without post HIP processing. 
     
     
         6 . The colored zirconia green body restoration in accordance with  claim 1 , wherein the colored zirconia green body restoration is milled from a green body without color pigment. 
     
     
         7 . The colored zirconia green body restoration in accordance with  claim 1 , wherein the colored zirconia green body restoration is subsequently finally sinterable to produce multiple color intensity with less color/chroma in an upper area and more color/chroma in a lower area.