Process for producing calcium phosphate ceramics having porous surface

• US 5,017,518 A
• Filed: 04/18/1990
• Issued: 05/21/1991
• Est. Priority Date: 09/14/1987
• Status: Expired due to Term

• Current Assignee: Asahi Kogaku Kogyo Kabushiki Kaisha
• Original Assignee: Asahi Kogaku Kogyo Kabushiki Kaisha
• Inventors: Ogawa, Tetsuro, Ojima, Satoshi, Hirayama, Yasuhiko
• Primary Examiner(s): Dixon, Jr., William R.
• Assistant Examiner(s): Green, Anthony J.
• Application Number:
  US07/511,814
• Time in Patent Office: 398 Days
• Field of Search: 501/1, 501/123, 501/80, 106/35
• US Class Current: 501/1
• CPC Class Codes: A61F 2310/00293 containing a phosphorus-containing compound, e.g. apatite
• CPC Class Codes: A61K 6/58 specially adapted for dental implants
• CPC Class Codes: A61K 6/75 Apatite
• CPC Class Codes: A61K 6/864 Phosphate cements apatite A61K6/838
• CPC Class Codes: A61L 27/12 Phosphorus-containing materials, e.g. apatite
• CPC Class Codes: B01J 20/048 containing phosphorus, e.g. phosphates, apatites, hydroxyapatites
• CPC Class Codes: B01J 20/28078 Pore diameter
• CPC Class Codes: B01J 20/3078 Thermal treatment, e.g. calcining or pyrolizing
• CPC Class Codes: B01J 20/3085 Chemical treatments not covered by groups B01J20/3007 - B01J20/3078
• CPC Class Codes: C04B 35/447 based on phosphates , e.g. hydroxyapatite
• CPC Class Codes: C04B 38/04 by dissolving-out added substances
• CPC Class Codes: C04B 41/009 characterised by the material treated
• CPC Class Codes: C04B 41/5353 Wet etching, e.g. with etchants dissolved in organic solvents
• CPC Class Codes: C04B 41/91 involving the removal of part of the materials of the treated articles, e.g. etching

Abstract

A process for producing calcium phosphate ceramics having a porous surface is described, which comprise the steps of:

a) preparing untreated calcium phosphate ceramics, which comprises a mixture of hydroxyapatite and tricalcium phosphate, and

b) treating said untreated ceramics with an acidic solution to selectively dissolve the tricalcium phosphate in the surface of the ceramics.

Claims

1. A process for producing calcium phosphate ceramics having a porous surface, comprising the steps of:

a) preparing untreated calcium phosphate ceramics, said untreated ceramics comprising a mixture of hydroxyapatite and tricalcium phosphate;

b) molding said untreated ceramics;

c) firing said untreated ceramics; and

d) contacting said untreated ceramics with an acidic solution to selectively dissolve the tricalcium phosphate in the surface of the ceramics but not selectively dissolve said hydroxyapatite;

wherein the pH of the acidic solution is from 1 to 5.5.

2. A process for producing calcium phosphate ceramics having a porous surface as claimed in claim 1, wherein the mixture of hydroxyapatite and tricalcium phosphate is controlled to give a calcium to phosphorus molar ratio (Ca/P) in the range from 1.53/1 to 1.64/1.

3. A process for producing calcium phosphate ceramics having a porous surface as claimed in claim 2, wherein the mixture of hydroxyapatite and tricalcium phosphate is controlled to give a calcium to phosphorus molar ratio (Ca/P) in the range from 1.57/1 to 1.64/1.

4. A process for producing calcium phosphate ceramics having a porous surface as claimed in claim 1, wherein the firing is at a temperature of from 700°

to 1,400°

C.

5. A process for producing calcium phosphate ceramics having a porous surface as claimed in claim 4, wherein the firing is at a temperature of from 1,000°

to 1,300°

C.

6. A process for producing calcium phosphate ceramics having a porous surface according to claim 8, wherein said step of contacting untreated ceramic with an acidic solution is performed for a time period of from 1 second to 24 hours.

7. Calcium phosphate based ceramics having a porous surface produced by the process comprising the steps of:

a) preparing untreated calcium phosphate ceramics, said untreated ceramics comprising a mixture of hydroxyapatite and tricalcium phosphate;

b) molding said untreated ceramics;

c) firing said untreated ceramics; and

d) contacting said untreated ceramics with an acidic solution to selectively dissolve the tricalcium phosphate in the surface of the ceramics but not selectively dissolve said hydroxyapatite so that the inner density of said ceramics is maintained;

wherein the pH of the acidic solution is from 1 to 5.5.