[Studies on alumina ceramics for dentistry--sinterable alumina for core material-- (author's transl)]

This study has been performed to introduce the industrial alumina ceramics having superior physico-chemical properties and desirable color for human tooth into dental field. The following results have been obtained through a series of experiments: 1) Effects of sintering of pure alumina powder were promoted more remarkably by adding a couple of additive together than by adding each, independently. 2) By adding a couple of additive, Li2O-Nb2O5 or MgO-Nb2O5, the effect of sintering was higly promoted, and tooth colored specimen was obtained. 3) At the alumina specimen sintered with 0.125 mol% of Nb2O5, a few initial shrinkage was seen and the process was followed by slowly increasing shrinkage through a rapid rate of heating. This suggested that a rapid heating was possible to be tried by using above additives. 4). The alumina ceramics with a couple of MgO-Nb2O5 prepared by heating at 1500 degrees C for 100 min., showed maximum bending strength of 42 kg/mm2 and 92.3 of R.A. hardness, which are rather higher value among other alumina ceramics. Though the luminosity might be too higher, chromaticity was as same as that of tooth shade.