Production manner null of bracket for dentition reform

摘要

PURPOSE:To impart high aesthetic toughness and mechanical strength to the above bracket by forming a molding by using zirconia powder which contains a specific ratio of yttria and is specific in crystal system, then heat-treating the molding at respectively specific pressures and temp. after sintering at a specific temp. CONSTITUTION:The zirconia powder which contains 1.7 to 3.2mol% yttria and has the crystal system consisting of a monoclinic crystal is molded to form a molding. The resulted molding is sintered at 1200 to 1400 deg.C to produce a sintered body of zirconia. The sintered body obtd. in such a manner is heat- treated at 1100 to 1400 deg.C under 1000 to 2000atm. The sintered body of zirconia is preferably of 0.12 to 0.5mum average crystal grain size of the tetragonal zirconia and 50mol% tetragonal zirconia content. The coloration to blue, pink, yellow, green and other colors is possible if one or =2 kinds of the oxides of Co, Cr, Mn, Ce, Cd, Sr, Fe, Cu, Zn, Sb, V, and Ni are incorporated at =0.5wt.% in total into the above-mentioned powder.