Non-pre- colored multi-layer zirconia dental blank that has a gradual change in chroma through a thickness after sintering

A dental block device for producing a dental prosthesis, the dental block device comprising:

• a) a green body comprising 60-99.9 wt % zirconia that is soft sintered or pre-sintered without color pigment;
• b) the green body having multiple different layers each having a different chemical composition between adjacent layers and being substantially opaque and white with a substantially consistent optical characteristic of color intensity/chroma across the layers;
• c) the different chemical composition including different amounts of yttria between adjacent layers with a lower layer having 4.5-6 wt % yttria and an upper layer having 6-10 wt % yttria;
• d) the green body having a brightness/lightness L* value between 10 to 20 for a sample thickness of 1 to 1.3 mm in accordance with CIE L*a*b* colorimetric system;
• and
• e) the green body is subsequently millable, colorable and sinterable to form the dental prosthesis with the multiple different layers having optical characteristics of gradually decreasing color intensity/chroma level towards an incisal or an occlusal area of the prosthesis after dipping in a color liquid and sintering.

A method for making a dental blank for use in producing a dental prosthesis, the method comprising:

• a) forming zirconia and yttria into a desired shape;
• b) increasing an amount of yttria through a thickness of the desired shape;
• and
• c) pre-sintering or soft sintering the desired shape to form a green body dental blank with a different chemical composition of the amount of yttria through the thickness and being substantially opaque with a substantially consistent optical characteristic of color intensity/chroma across the thickness, the green body dental blank having a brightness/lightness L* value between 10 to 20 for a sample thickness of 1 to 1.3 mm in accordance with CIE L*a*b* colorimetric system.

A method for making a dental a dental prosthesis, the method comprising:

• a) obtaining a green body dental blank including zirconia and having multiple different layers each having a different chemical composition with different amounts of yttria between adjacent layers and being substantially opaque and white with a substantially consistent optical characteristic of color intensity/chroma across the layers, the green body dental blank having a brightness/lightness L* value between 10 to 20 for a sample thickness of 1 to 1.3 mm in accordance with CIE L*a*b* colorimetric system;
• b) milling a green body dental prosthesis from the dental blank;
• c) coloring the green body dental prosthesis by dipping the green body dental prosthesis into a specific color liquid;
• d) sintering the green body dental prosthesis to form the dental prosthesis with the multiple different layers having different optical characteristics of color intensity/chroma after sintering.