Hydroxylapatite ceramic
AssigneeSterling Drug Inc.
InventorMichael Jarcho
Life of this patent
Estimating the term…
Abstract
A novel ceramic form of hydroxylapatite and a novel ceramic product comprising a mixture of the latter and whitlockite, the preparation of these ceramics and dental restorative compositions and dental and surgical prosthetic materials containing the same are disclosed. Also described is a novel and improved process for producing polycrystalline ceramic oxides.
Claims43
As an article of manufacture, substantially pure hydroxylapatite in the form of a translucent, isotropic, polycrystalline, sintered ceramic having an average crystallite size in the approximate range 0.2 to 3 microns, a density greater than approximately 98 percent of the theoretical density of hydroxylapatite and being further characterized by the absence of pores and by cleavage along smooth curved planes.
As an article of manufacture, a strong, hard, dense, isotropic, polycrystalline sintered biphasic ceramic comprising as one phase from about 20 to 95 percent by weight of hydroxylapatite and as a second phase from about 5 to 80 percent by weight of whitlockite and being characterized by the absence of pores and by cleavage along smooth curved planes.
The process which comprises reacting calcium ion with phosphate ion in aqueous medium at a pH of about 10-12 to produce a gelatinous precipitate of a phosphate of calcium having a molar ratio of calcium to phosphorus between the approximate molar ratio of calcium to phosphorus in whitlockite and that in hydroxylapatite, separating said gelatinous precipitate from solution, heating said gelatinous precipitate up to a temperature of at least approximately 1000.degree. C. but below that at which appreciable decomposition of hydroxylapatite occurs, and maintaining said temperature for sufficient time to effect the sintering and substantially maximum densification of the resulting product.
Dependencies are inferred from the claim text.