Fabrication of polychromatic/polytranslucent zirconia block from pre-shaded ZrO2 block by infiltration

1 . A method for making a polychromatic/polytranslucent ceramic block from a pre-shaded porous ceramic body, comprising:

(a) obtaining a pre-shaded porous ceramic body comprising

i. a first end surface adjacent a first porous region, and

ii. a second end surface adjacent a second porous region, opposite the first end surface; and

(b)(1) infiltrating a yttrium-containing solution through the first end surface to occupy the first porous region adjacent the first end thereby weakening a chroma level and increasing a translucency of the first porous region;

(c)(1) after infiltrating the yttrium-containing solution through the first end surface, inverting the yttrium-containing solution-infiltrated ceramic body;

(d)(1) after inverting the yttrium-containing solution-infiltrated ceramic body, infiltrating water through the second end surface to occupy the second porous region adjacent the second end thereby not changing a chroma level or a translucency of the second porous region;

(e)(1) contacting a portion of the yttrium-containing solution in the first porous region with a portion of the infiltrating water in the second porous region at an interface; and

(f)(1) forming within the interface a chroma/translucency gradient region resulting in a polychromatic/polytranslucent ceramic block.

2 . The method of claim 1 , wherein the pre-shaded porous ceramic body further comprises a side surface that is continuous between the first end and second end surfaces, and the method further comprises contacting and covering the second end surface and the side surface with a casing material, wherein the casing material contacting the second end surface and side surface prevents the yttrium-containing solution from passing through the second end surface and the side surface; removing the casing material from the second end surface and side surface, inverting the ceramic body, and covering the first end surface and side surface with the casing material, wherein the casing material on the first end and the side surface prevents the water and the yttrium-containing solution from passing through the first end surface and side surface.

3 . The method of claim 1 , comprising infiltrating between 3% by volume and 75% by volume porosity of the porous ceramic body with the yttrium-containing solution, and infiltrating between 25% by volume and 97% by volume porosity of the porous ceramic body with the water.

4 . The method of claim 1 , wherein the porous ceramic body is a zirconia ceramic body.

5 . The method of claim 1 , wherein the yttrium-containing solution comprises yttrium nitrate.

6 . The method of claim 1 , wherein the yttrium-containing solution comprises yttrium chloride.

7 . The method of claim 1 , further comprising producing a dental restoration from the polychromatic/polytranslucent block wherein the first porous region corresponds to an incisal area of the dental restoration and the second porous region corresponds to a body area of the dental restoration.

8 . The method of claim 1 , further comprising producing a dental restoration from the polychromatic/polytranslucent block wherein the interfacial color/translucency gradient region is between an incisal area and a cervical area of the dental restoration, and the interfacial color/translucency gradient region is the only the interfacial color/translucency gradient region present in the dental restoration.

9 . The method of claim 1 , wherein the pre-shaded porous ceramic body is a monochromatic porous ceramic body.

10 . A method for making a polychromatic/polytranslucent ceramic block from a pre-shaded porous ceramic body comprising:

(a) positioning a pre-shaded porous ceramic body within a casing, wherein the casing has a side wall and a bottom, and wherein the pre-shaded porous ceramic body comprises a side surface, a first end surface adjacent a first porous region, and a second end surface adjacent a second porous region opposite the first end surface, and the bottom and the side wall of the casing contact the second end surface and side surface of the pre-shaded porous ceramic body such that the side wall of the casing extends beyond the first end surface of the pre-shaded porous ceramic body and forms a reservoir;

(b) providing a volume of a yttrium-containing solution within the reservoir on the first end surface of the pre-shaded porous ceramic body;

(c) infiltrating the yttrium-containing solution through the first end surface of the pre-shaded porous ceramic body into a first porous region of the pre-shaded porous ceramic body thereby weakening a chroma level and increasing a translucency of the first porous region, wherein the casing material prevents the yttrium-containing solution from passing through the second end surface and the side surface of the pre-shaded porous ceramic body;

(d) after infiltrating the yttrium-containing solution through the first end surface of the pre-shaded porous ceramic body, inverting the pre-shaded porous ceramic body within the casing, wherein the first end surface is in contact with the bottom of the casing, and the side wall of the casing conforms to and contacts the side surface of the pre-shaded porous ceramic body;

(e) after inverting the pre-shaded porous ceramic body, providing a volume of water within the reservoir on the second end surface;

(f) infiltrating the water through the second end surface into a second porous region that is adjacent the first porous region thereby not changing a chroma level or a translucency of the second porous region, wherein the casing material prevents the yttrium-containing solution and the water from passing through the first end surface and the side surface of the pre-shaded porous ceramic body;

(g) contacting a portion of the water in the second porous region with a portion of the yttrium-containing solution in the first porous region at an interface between the first porous region and the second porous region, and then mixing to form a color/translucency gradient region and

(h) sintering the infiltrated pre-shaded porous ceramic body to form a sintered ceramic body comprising a first color/translucency region adjacent the first end surface, a second color/translucency region adjacent the second end surface, and a color/translucency gradient region there between.