Zirconia sintered body, zirconia composition, zirconia pre-sintered body and dental prosthesis

A zirconia sintered body configured for dental application, comprising a plurality of sintered layers,

• wherein a flexural strength of a test sample of the zirconia sintered body, measured pursuant to JISR1601, is not less than 90% of the flexural strength of a comparative zirconia sintered body,
• wherein the test sample being formed by:
• preparing a plurality of zirconia powders, each comprising zirconia and yttria as a stabilizer that suppresses phase transition of zirconia, the plurality of zirconia powders differing in composition;
• laminating the plurality of zirconia powders to form a plurality of zirconia powder layers;
• vibrating the zirconia powder layers to produce interlayer boundary portions having compositional mixtures of respective zirconia powders of respective adjacent pairs of the plurality of zirconia powder layers;
• and
• sintering the plurality of zirconia powder layers to form the zirconia sintered body,
• wherein the comparative zirconia sintered body is formed by sintering one composition of the plurality of zirconia powders alone at the same temperature as a sintering temperature of the test sample,
• wherein as a result of the sintering, each of the plurality of zirconia powders becomes a respective one layer of the plurality of sintered layers, the interlayer boundary portions of the plurality of sintered layers having a gradient of the compositional mixture of each of the respective adjacent pairs of the plurality of sintered layers, and
• wherein the flexural strength of the test sample is measured under a condition that a load point of a three-point bending test is positioned at a position of an interlayer boundary of the sintered layers, the interlayer boundary traversing the test sample of the pre-sintered body along a direction of load application.