Chemistry of inorganic compounds – Treating mixture to obtain metal containing compound – Alkaline earth metal
Patent
1987-09-16
1988-09-13
Foelak, Morton
Chemistry of inorganic compounds
Treating mixture to obtain metal containing compound
Alkaline earth metal
423164, C01F 502
Patent
active
047708603
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a porous hydroxyl apatite material and to the employment thereof in medicine, dentistry and veterinary medicine.
From U.S. Pat. No. 3,929,971, there is already known a synthetic, porous hydroxyl apatite material which has a special microstructure and which may be employed as a biomaterial, e.g. as a prosthesis material, bone implant and the like. This previously known hydroxyl apatite material is made from the carbonate skeletons of sea animals, in particular corals and starfish.
It is an object of the present invention to provide a novel porous hydroxyl apatite material which, because of the starting materials employed in its manufacture, has a special porosity and which exhibits a special form.
For this purpose, there serves the porous hydroxyl apatite material which is characterized in that the material is produced from the calcium-rich basic skeletons of lime-encrusting algae converted into the hydroxyl apatite material.
According to preferred embodiments of the invention, the pores of the porous hydroxyl apatite material are filled with a re-absorbable or a bone-inducing material such as bone marrow.
The porous hydroxyl apatite material according to the invention is useful, in particular, as artificial bone, artificial tooth root, stabilizing material, artificial hollow bodies, supplementary material, lining material or defect-filling material.
For the production of the hydroxyl apatite material, according to the invention all algae, and in particular those from the littorals and sub-littorals of the oceans, in particular species of Corallinaceae such as Corallina officinalis, Corallium, rubens, Lithothamion calcarum and species of Codiaceae, e.g. Halimeda spec., including benthish crust-forming algae such as Lithothamnion spec. and Lithophyllum spec. can be used, which, in general, encrust lime, even if only to a small extent.
In order to obtain the lime skeletons of the algae, the organic components of the algae must firstly be removed. This can be effected by so-called "maceration". For this purpose, for example, vital or dried algae material can be treated with copper complex salts, e.g. Schweizer's reagent or with lithium chloride or bromide solutions, or subjected to pyrolysis. Such maceration processes, i.e. methods of treatment for removing the organic material, are likewise described in the aforesaid U.S. Pat. No. 3,929,971, e.g. submersion in dilute sodium hypochlorite solutions.
Following the maceration by means of Schweizer's reagent or lithium chloride solution, or after pyrolysis, the remaining calcium carbonate basic material, freed of organic substance and existing in granular form, is thoroughly washed with distilled water. The grain size of the material is between 0.1 and 2 millimeters.
The calcium-rich basic skeleton obtained from the algae is then converted into hydroxyl apatite in a known manner. This conversion into hydroxyl apatite is usually effected by a hydrothermal process or by the use of a phosphate salt bath. For this purpose, alkali metal phosphates such as sodium orthophosphate, potassium orthophosphate and ammonium orthophosphate, acidic phosphates and phosphate mixtures may be employed. Likewise, orthophosphoric acids may also be employed for this purpose. This hydrothermal treatment for converting calcium carbonate into hydroxyl apatite is likewise disclosed in the aforesaid U.S. Pat. No. 3,929,971. The hydrothermal treatment is carried out in the usual way at high pressure and at high temperature.
An example for such a treatment comprises maintaining the porous, macerated granules of lime-encrusting algae with sodium hydrogen phosphate and doubly-distilled water in proportions of 1:1:4 in a closed container for two to three days under the following conditions:
Depending upon the physical conditions employed, an influence can be exerted on the re-absorbability of the material in bone surgery.
After the hydrothermal treatment, the hydroxyl apatite material usually exhibits a granular form. From this granular form, compact pieces can be
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patent: 2067538 (1937-01-01), MacIntire
patent: 2143025 (1939-01-01), Newton
patent: 3236593 (1966-02-01), Hartmann
Ewers Rolf
Kasperk Christian
Ewers Rolf
Foelak Morton
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