Multi-layer zirconia dental blank that has a gradual change in strength, translucency and chroma from one direction to the other after sintering

A zirconia sintered body, comprising:

• a) a sintered body comprising zirconia;
• b) the sintered body having multiple different areas including at least one upper area and at least one lower area;
• c) each of the at least one upper area and the at least one lower area having a different chemical composition therebetween;
• and
• d) the sintered body having a strength and a color intensity/chroma, with the strength decreasing in one direction across the multiple different areas with at least a part of the sintered body having a strength of at least 925 Mpa, and the color intensity/chroma also decreasing in the same direction across the multiple different areas, with a chroma (a*, b*, C*ab, L*) by CIELAB colorimetric system of a point A within a 30% vertical area on the one side being Aa*, Ab*, AC*ab, AL* and a chroma (a*, b*, C*ab, L*) by CIELAB colorimetric system of a point B within a 30% vertical area on the other side being Ba*, Bb*, BC*ab, BL*, where:
• Aa*>Ba*, while a* is decreasing from point A to point B, and
• Ab*>Bb*, while b* is decreasing from point A to point B, and
• AC*ab>BC*ab, while C*ab is decreasing from point A to point B, and
• AL*<BL*, while L* is increasing from point A to point B.

A zirconia sintered body, comprising:

• a) a sintered body comprising zirconia and having multiple different areas, including at least one upper area and at least one lower area having a different chemical composition therebetween;
• b) the different chemical composition including different amounts of yttria between the at least one upper layer and the at least one lower layer;
• c) the amount of yttria is increased incrementally from 4.5-10 wt % in the at least one lower area to 6-20 wt % in the at least one upper area with the at least one upper area having higher yttria amount than the at least one lower area;
• and
• d) the sintered body having a translucency and a color intensity/chroma with an inverse relationship, with the translucency increasing in one direction across the multiple different areas and the color intensity/chroma decreasing in the same direction across the multiple different areas, with at least a part of the 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, with a chroma (a*, b*, C*ab, L*) by CIELAB colorimetric system of a point A within a 30% vertical area on the one side being Aa*, Ab*, AC*ab, AL* and a chroma (a*, b*, C*ab, L*) by CIELAB colorimetric system of a point B within a 30% vertical area on the other side being Ba*, Bb*, BC*ab, BL*, where:
• Aa*>Ba*, while a* is decreasing from point A to point B, and
• Ab*>Bb*, while b* is decreasing from point A to point B, and
• AC*ab>BC*ab, while C*ab is decreasing from point A to point B, and
• AL*<BL*, while L* is increasing from point A to point B.

A zirconia sintered body, comprising:

• a) a sintered body comprising zirconia and 6 to 20 wt % of yttria;
• b) the sintered body having multiple different areas including at least one lower area and at least one upper area;
• c) the at least one upper area and the at least one lower area having a different chemical composition, including an amount of yttria, therebetween, with at least one area having a different strength than another area;
• d) the sintered body having a strength, a translucency and a post-sintered color intensity/chroma, with the translucency increasing in one direction across the multiple different areas and the strength and the color intensity/chroma decreasing in the same direction across the multiple different areas with at least a part of the sintered body having a strength of at least 925 Mpa, with at least a part of the 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, and with a chroma (a*, b*, C*ab, L*) by CIELAB colorimetric system of a point A within a 30% vertical area on the one side being Aa*, Ab*, AC*ab, AL* and a chroma (a*, b*, C*ab, L*) by CIELAB colorimetric system of a point B within a 30% vertical area on the other side being Ba*, Bb*, BC*ab, BL*, where:
• Aa*>Ba*, while a* is decreasing from point A to point B, and
• Ab*>Bb*, while b* is decreasing from point A to point B, and
• AC*ab>BC*ab, while C*ab is decreasing from point A to point B, and
• AL*<BL*, while L* is increasing from point A to point B.