| 摘要 |
PCT No. PCT/AT92/00088 Sec. 371 Date Jan. 3, 1994 Sec. 102(e) Date Jan. 3, 1994 PCT Filed Jul. 9, 1992 PCT Pub. No. WO93/00865 PCT Pub. Date Jan. 21, 1993.An orthodontic device comprises a ceramic tooth attachment comprising a base body having an in-line transmittance of visible light in the range of 5% to 60% through a thickness of 0.5 mm and the base body consisting of polycrystalline grains comprising a substance selected from the group of high purity zircon, high purity yttrium oxide, lead titanate zirconate and an aluminum oxide, and X-ray visible precipitations arranged on grain boundaries between the polycrystalline grains, the precipitations comprising ytterbium fluoride in a concentration range of 3 to 150 ppm. |
