Compositions: ceramic – Ceramic compositions – Devitrified glass-ceramics
Reexamination Certificate
2002-06-13
2004-07-27
Group, Karl (Department: 1755)
Compositions: ceramic
Ceramic compositions
Devitrified glass-ceramics
C501S001000, C501S032000, C501S102000, C501S044000, C501S046000, C065S033300
Reexamination Certificate
active
06767854
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention refers to a glassy-crystalline material with low solubility which can be used both as bioactive bone replacement material, e.g. in the form of a coating applied onto metallic prosthesis sticks by thermal spraying, and as substrate material in biotechnology, e.g. in the form of a ceramic sheet or body. The invention also refers to a manufacturing method.
2. Description of the Related Art
In principal, long-term stable inorganic materials are known. Materials that are specifically used as bioactive bone replacement materials and have a sufficient long-term stability have also been described in the relevant literature. For example, there have been continuous publications dedicated to the successful clinical use of glass ceramics and sintered glass ceramics the main crystal phases of which are apatite and wollastonite [Kokubo, T., Biomaterials, 12 (1991) 155-163; Berger, G. et al.: Long-term stable bioactive glass ceramics as implant material—ten years of clinical experience, Fourth World Biomaterial Congress, Berlin, Apr. 24-28, 1992, Transactions p. 33]. The chemical stability of the aforesaid materials has been surpassed by that of other bioactive materials on the basis of calcium-zirconium/titanium phosphate (Biomaterials 18 (1997) 1671-1675) which can only be manufactured using ceramic methods, but do not melt at temperatures which are common in the glass industry (approximately 1650° C.), which is known to cause disadvantages as regards the mechanical stability of such granulated materials and particularly of bodies manufactured thereof.
The object of the invention is to provide a glassy-crystalline material, which enables bones to be directly joined with no connective tissue in between and which at the same time is long-term stable.
SUMMARY OF THE INVENTION
According to the invention, the glassy-crystalline material on the basis of CaO, P
2
O
5
, ZrO
2
and fluoride consists of 15-45% by weight CaO, 40-45% by weight P
2
O
5
, 10-40% by weight ZrO
2
and 0.7-3.5% by weight of fluoride and contains apatite and calcium zirconium phosphate as main crystal phases and a glass phase as secondary component, the main crystal phases jointly making up at least 35% by weight and the secondary components making up 5 to 15% by weight, and all percentages being relative to the total weight of the glassy-crystalline material.
REFERENCES:
patent: 4376168 (1983-03-01), Takami et al.
patent: 4871384 (1989-10-01), Kasuga
patent: 62268561 (1987-11-01), None
Derwent Abstract 1988-004048 of JP 62-268561A.*
Berger, et al., “Hydroxyapatite's Solubility May Cause Loosening of Coated Implants”, Key Engineering Materials vols. 192-195 (2001) pp. 111-114.
Berger, et al., “Long-Term Stable Bioactive Glass Ceramics as Implant Material—Ten Years of Clinical Experience”, Fourth World Biomaterials Congress, Apr. 24-28, 1992.
Kukubo, Tadashi; “Bioactive glass ceramics: properties and applications”, Biomaterials 1991, vol. 12 Mar.
Ploska, et al., “Solubility of compositions in the system CaTixZr4-x(PO4)6 with x=0-4”, Biomaterials 1997, vol. 18, No. 24.
Berger, et al., “Clinical Application of Surface Reactive Apatite/Wollastonite Containing Glass-Ceramics”, XV. Int. Congress on Glass, Leningrad, USSR, 3,-7.7. 1989, vol. 3a, pp. 120-136.
Berger Georg
Ploska Ute
Bam Bundesanstalt fuer Materialforschung und Prufung
Bolden Elizabeth A.
Group Karl
Pendorf & Cutlitf
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