Multi-Layer Zirconia Dental Blank that has a Gradual Change in Strength, Translucency and Chroma from One Direction to The Other After Sintering

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 has a substantially consistent optical characteristic of chroma and translucency across the thickness, and is subsequently millable and sinterable to form the dental prosthesis with an optical characteristic of decreasing chroma, increasing translucency, and decreasing strength, in one direction through a thickness of the dental prosthesis.

What is claimed is: 
     
         1 . A dental block device for producing a dental prosthesis, the dental block device comprising:
 a) a green body comprising zirconia;   b) the green body having multiple different areas each having a different chemical composition between adjacent areas; and   c) the green body having a pre-sintered translucency that is substantially the same across the multiple different areas, and the green body subsequently having a post-sintered translucency and a post-sintered strength with an inverse relationship with the post-sintered translucency increasing in one direction across the multiple different areas and the strength decreasing in the same direction across the multiple different areas.   
     
     
         2 . The device in accordance with  claim 1 , wherein the green body has a color component. 
     
     
         3 . The device in accordance with  claim 1 , wherein the green body is without a color component. 
     
     
         4 . The device in accordance with  claim 1 , wherein the different chemical composition includes different amounts of yttria between the adjacent areas. 
     
     
         5 . The device in accordance with  claim 4 , wherein the amount of yttria is increased incrementally from 4.5-6 wt % in the lower area to 6-10 wt % in the upper area. 
     
     
         6 . The device in accordance with  claim 1 , wherein the post-sintered strength of the lower area of the dental prosthesis or dental block is higher than the upper area. 
     
     
         7 . The device in accordance with  claim 6 , wherein the strength is flexural strength. 
     
     
         8 . The device in accordance with  claim 1 , wherein the post-sintered translucency of the upper area of the dental prosthesis or dental block is higher than the lower area. 
     
     
         9 . The device in accordance with  claim 8 , wherein the translucency is total light transmittance. 
     
     
         10 . A dental block device for producing a dental prosthesis, the dental block device comprising:
 a) a green body comprising zirconia;   b) the green body having multiple different areas each having a different chemical composition between adjacent areas; and   c) the green body subsequently having a post-sintered strength and a post-sintered color intensity/chroma with the post-sintered strength increasing in one direction across the multiple different areas and the post-sintered color intensity/chroma also increasing in the same direction across the multiple different areas.   
     
     
         11 . The device in accordance with  claim 10 , wherein the different chemical composition includes different amounts of yttria between the adjacent areas. 
     
     
         12 . The device in accordance with  claim 11 , wherein the amount of yttria is increased incrementally from 4.5-6 wt % in the lower area to 6-10 wt % in the upper area. 
     
     
         13 . The device in accordance with  claim 10 , wherein the post-sintered strength of the lower area of the dental prosthesis or dental block is higher than the upper area. 
     
     
         14 . The device in accordance with  claim 13 , wherein the strength is flexural strength. 
     
     
         15 . The device in accordance with  claim 10 , wherein the post-sintered translucency of the upper area of the dental prosthesis or dental block is higher than the lower area. 
     
     
         16 . The device in accordance with  claim 15 , wherein the translucency is total light transmittance. 
     
     
         17 . A dental block device for producing a dental prosthesis, the dental block device comprising:
 a) a green body having multiple different areas each having a different chemical composition between adjacent areas;   b) the different chemical composition including different amounts of yttria between the adjacent areas;   c) the amount of yttria is increased incrementally from 4.5-6 wt % in a lower area to 6-10 wt % in an upper area; and   d) the green body having a pre-sintered translucency that is substantially the same across the multiple different areas, and the green body subsequently having a post-sintered translucency and a post-sintered color intensity/chroma with an inverse relationship with the post-sintered translucency increasing in one direction across the multiple different areas and the post-sintered color intensity/chroma decreasing in the same direction across the multiple different areas.   
     
     
         18 . The device in accordance with  claim 17 , wherein the green body has a color component. 
     
     
         19 . A dental block device for producing a dental prosthesis, the dental block device comprising:
 a) a green body comprising zirconia;   b) the green body having multiple different areas including a lower area configured to correspond to a cervical area of the dental prosthesis produced from the dental block and an upper area configured to correspond to an incisal area of the dental prosthesis;   c) the green body having a pre-sintered translucency that is substantially the same across the multiple different areas, and the green body subsequently having a post-sintered translucency and a post-sintered color intensity/chroma with an inverse relationship with the post-sintered translucency increasing in one direction across the transmittance. multiple different areas and the post-sintered color intensity/chroma decreasing in the same direction across the multiple different areas.   
     
     
         20 . The device in accordance with  claim 19 , wherein a color component is introduced to the green body. 
     
     
         21 . The device in accordance with  claim 19 , wherein each area has a different chemical composition between adjacent areas, including different amounts of yttria between adjacent areas, with the amount of yttria increased from the lower area to the upper area; and wherein the amount of yttria is increased incrementally from 4.5-6 wt % in the lower area to 6-10 wt % in the upper area.