To provide a preparing method of a zirconia mill blank for dental cutting and machining having any one or more of translucency gradation, color gradation and strength gradation after perfect sintering by impregnating a zirconia calcined body with a plurality of impregnating solutions, which can suppress deterioration of the fitting property of a dental prosthesis device prepared from the zirconia mill blank for dental cutting and machining and a zirconia mill blank for dental cutting and machining having any one or more of translucency gradation, color gradation and strength gradation after perfect sintering and suppressing deterioration of the fitting property of a dental prosthesis device prepared from the zirconia mill blank for dental cutting and machining.

To porovide a zirconia mill blank for dental cutting and machining of the present invention is a preparing method of a zirconia mill blank for dental cutting and machining having any one or more of translucency gradation, color gradation and strength gradation after perfect sintering, comprising a step of impregnating a zirconia calcined body with at least two types of impregnating solutions, wherein at least one of the impregnating liquids contains a zirconium component, and in a case in which the total of metal ion concentrations (mass %) contained in each impregnating liquid is defined as C.sub.total, the difference ?C.sub.total which is a difference between C.sub.total of each impregnating liquid is 5.0 or less.

To provide a zirconia mill blank for dental cutting and machining that can impart translucency gradation and color gradation similar to a natural tooth to a zirconia perfect sintered body without the need for special equipment.

To provide a zirconia mill blank for dental cutting and machining comprising two opposing surfaces and a side surface between the two opposing surfaces, wherein the side surface has a rectangular shape in a side view of the zirconia mill blank for dental cutting and machining, and in a case in which one of the two opposing surfaces is defined as surface A, the other surface of the two opposing surfaces is defined as surface B, a surface which is parallel to the surface A and is located at a position of 1.0 mm to 1.5 mm from the surface A toward the surface B in a direction parallel to the side surface is defined as surface C, points which are set to having 0.5 mm of distance on the straight line in the direction parallel to the side surface from the surface C toward the surface B in the area from the surface C to the surface B are defined as point P(1), point P(2), to point P(n) in the order from the surface C, a stabilizer concentration (mol %) at each point is defined as SP(1), SP(2), to SP(n) (n?((shortest distance (mm) between the surface C and the surface B)?2)/0.5), the maximum value of the stabilizer concentration (mol %) is defined as SPmax, the minimum value of the stabilizer concentration (mol %) is defined as SPmin, and the maximum value of ASP(m) defined by the following formula is defined as ?SPmax, the zirconia mill blank for dental cutting and machining has a portion where the value of SPmax?Spmin which is a difference between the SPmax and the SPmin is 0.3 or more, and the ?SPmax is less than 0.5.

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