Method for enhancing optical properties in ceramics having applications in dental restorations

A method for applying an yttria-containing composition to enhance optical properties of a sintered zirconia ceramic body, comprising an application method comprising

• applying a first application of an aqueous yttria-containing composition to an edge of a porous ceramic dental restoration form comprising an yttria-stabilized zirconia ceramic material for a first application distance of 1 mm to 5 mm from the edge, and penetrating a portion of the porous ceramic dental form,
• wherein the yttrium-containing composition comprises between 30% wt and 70% wt yttrium-containing material, between 0.05M and 5M citric acid, and a colorant comprising at least one metal-containing component as a coloring agent;
• applying a second application of the yttria-containing composition to the edge for a second application distance of 0.5 mm to 3 mm from the edge, penetrating the portion of the porous ceramic dental restoration form containing the aqueous yttria-containing composition from the first application, wherein the second application distance is less than the first application distance, wherein the application method provides at least 46% or greater transmittance at 700 nm when applied to a porous zirconia ceramic body made from the yttria-stabilized zirconia ceramic material having a 1 mm target thickness when sintered to at least 98% theoretical density;
• and
• wherein a difference in L* values (CIE color space) between (i) a sintered zirconia ceramic body having the first and second applications of the yttrium-containing composition and (ii) an untreated sintered zirconia ceramic body is less than or equal to 6%;
• and
• sintering the porous ceramic dental restoration form after the first and second application to form a dental restoration.

Method for enhancing the translucency of a sintered zirconia dental restoration comprising

• obtaining a porous zirconia ceramic body formed from an yttria-stabilized zirconia powder comprising 2 mol % yttria to 5 mol % yttria,
• wherein the porous zirconia ceramic body is in the shape of a dental restoration;
• obtaining an yttrium-containing composition comprising between 20 wt % and 70 wt % of an yttrium salt dissolved in an aqueous solvent, between 0.05M and 5M citric acid, and a colorant comprising at least one metal-containing component as a coloring agent;
• and
• providing a first application of the yttrium-containing composition to penetrate a portion of the porous zirconia ceramic body;
• providing a second application of the yttrium-containing composition to penetrate the portion of the porous zirconia ceramic body that comprises the yttrium-containing composition of the first application;
• and
• sintering the porous zirconia ceramic body after the first and second applications to form a sintered zirconia dental restoration;
• wherein a difference in L* values (CIE color space) between (i) a sintered zirconia ceramic body having the first and second applications of the yttrium-containing composition and (ii) an untreated sintered zirconia ceramic body is less than or equal to 6%.