# US 5,702,677 A · Spherical hydroxyapatite particles and process for the production thereof > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,702,677 A - Document ID: US5702677A - Status: Granted - Kind: A - Application number: 08/679,611 - Filed: 1996-07-10 - Granted: 1997-12-30 - Earliest claimed: 1996-07-10 - Assignees: Osteotech, Inc. - Inventors: Lawrence A. Shimp; Peter J. Renkema - Web page: https://patentgrep.com/patent/US5702677A ## CPC - A61L 27/32: Phosphorus-containing materials, e.g. apatite - A61K 6/17: Particle size - A61K 6/54: Filling; Sealing - A61K 6/75: Apatite - A61L 27/12: Phosphorus-containing materials, e.g. apatite - C01B 25/322: {Preparation by neutralisation of orthophosphoric acid} - A61F 2310/00293: containing a phosphorus-containing compound, e.g. apatite - A61F 2310/00796: Coating or prosthesis-covering structure made of a phosphorus-containing compound, e.g. hydroxy(l)apatite - A61L: METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES (preservation of bodies or disinfecting characterised by the agents employed A01N; preserving, e.g. sterilising, food or foodstuffs A23; preparations for medical, dental or toiletry purposes A61K) - A61K: PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES (devices or methods specially adapted for bringing pharmaceutical products into particular physical or administering forms A61J3/00; chemical aspects of, or use of materials for deodorisation of air, for disinfection or sterilisation, or for bandages, dressings, absorbent pads or surgical articles A61L; soap compositions C11D) - C01B: NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; {METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C} - A61F: FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS (dental prosthetics A61C) ## Abstract A process for producing spherical, non-porous hydroxyapatite particles having a size which does not exceed 250 microns and having a density of at least 3.00 g/cc. The process comprises agglomerating in the presence of water as the only additive hydoxyapatite powder feedstock having a purity of at least 97%, and having metallic impurities which do not exceed 500 ppm, to form hydroxyapatite particles having a size which does not exceed 350 microns. The particles are then dried and then sintered at a temperature from about 1,100.degree. C. to about 1,200.degree. C. to provide spherical, non-porous hydoxyapatite particles which do not exceed 250 microns and having a density of at least 3.00 g/cc. Such particles have a variety of medical uses, including bone replacement, implant coatings, and dental applications such as alveolar ridge augmentation, root extraction site fillings, restoration of periodontal osseous lesions, and soft tissue augmentations. ## Claims ### Claim 1 A process for producing spherical, non-porous hydroxyapatite particles having a size which does not exceed 250 microns, and having a density of at least 3.00 g/cc, comprising: agglomerating in the presence of water as the only additive a hydroxyapatite powder feedstock having a purity of at least 97% and having metallic impurities which do not exceed 500 ppm, to form hydroxyapatite particles having a size which does not exceed 350 microns; drying said hydroxyapatite particles; and sintering said dried hydroxyapatite particles at a temperature of from about 1,100.degree. C. to about 1,200.degree. C. to provide spherical, non-porous hydroxyapatite particles having a size which does not exceed 250 microns and having a density of at least 3.00 g/cc. ### Claim 2 (depends on 1) The process of claim 1 wherein said hydroxyapatite powder has a purity of at least about 98%. ### Claim 3 (depends on 1) The process of claim 1 wherein said hydroxyapatite powder has metallic impurities which do not exceed 350 ppm. ### Claim 4 (depends on 3) The process of claim 3 wherein said hydroxyapatite powder has metallic impurities which do not exceed 300 ppm. ### Claim 5 (depends on 1) The process of claim 1 wherein said spherical non-porous hydroxyapatite particles have a size of from about 75 microns to about 125 microns. ### Claim 6 (depends on 1) The process of claim 1 wherein said spherical hydroxyapatite particles are sintered at a temperature of about 1,200.degree. C. ### Claim 7 (depends on 1) The process of claim 1 wherein said hydroxyapatite powder feedstock, prior to agglomeration, has an average particle size under 25 microns. ### Claim 8 (depends on 1) The process of claim 1 wherein said spherical non-porous hydroxyapatite particles have a density of at least 3.02 g/cc. ### Claim 9 (depends on 1) Hydroxyapatite particles produced according to the process of claim 1. ### Claim 10 A process for producing spherical, non-porous hydroxyapatite particles having a size which does not exceed 250 microns, and having a density of at least 3.00 g/cc, comprising: reacting calcium hydroxide having a purity of at least 95%, and having metallic impurities which do not exceed 500 ppm, with phosphoric acid, in the absence of dispersants or surfactants, to provide a hydroxyapatite powder feedstock having a purity of at least 97% and having metallic impurities which do not exceed 500 ppm; agglomerating said hydroxyapatite feedstock in the presence of water as the only additive to form hydroxyapatite particles having a size which does not exceed 350 microns; drying said hydroxyapatite particles; and sintering said dried hydroxyapatite particles at a temperature of from about 1,100.degree. C. to about 1,200.degree. C. to provide spherical, non-porous hydroxyapatite particles having a size which does not exceed 250 microns and having a density of at least 3.00 g/cc.