JPH10179716A - Vital prosthetic member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a vital prosthetic member which has high mechanical strength and good biocompatibility with a living body and is stable in the living body without the occurrence of peeling and dislodging of calcium phosphate from its base body. SOLUTION: A glass film as an intermediate film is formed of apatite wollastonite crystallized glass (AWGC) on the ceramic base body consisting of alumina, zirconia, etc., and the average film thickness thereof is controlled to 10 to 30μm. A film consisting of calcium phosphate, such as hydroxyapatite, is deposited thereon via the AWGC and the average film thickness thereof is controlled to 10 to 30μm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bioprosthesis for repairing hard tissue in a human body.

[0002]

2. Description of the Related Art Ceramic materials having excellent affinity have been attracting attention as materials for repairing hard tissues in a living body, and various artificial bones, artificial joints and artificial roots already formed of alumina ceramic have been put to practical use. On the other hand, artificial dental roots made of hydroxyapatite are also being put to practical use. Of these ceramic materials used as bioprostheses, alumina ceramics have excellent stability and great mechanical strength in vivo, but they are inactive materials and therefore natural bone after being implanted in a living body. It takes a considerably long time to reach an adhesion and fixation to the natural bone due to the growth of the natural bone.
In addition, when an artificial bone, an artificial joint, or the like is formed of hydroxyapatite, which is a bioactive material, the period required for bonding and fixing with a living body is relatively short, but there is a major drawback that hydroxyapatite itself has low mechanical strength.

[0003] Apatite-wollastonite crystallized glass (hereinafter abbreviated as AWGC) as a biomaterial is a ceramic-like substance made by reheating and crystallizing glass, and has a mechanical strength of glass. It is made by crystallizing glass in order to increase the mechanical strength, bending strength is stronger than cortical bone, and calcium ions and sulfate ions elute from the glass layer and wollastonite crystals in vivo, The ions react with calcium ions and phosphate ions in the body fluid to form an apatite layer, and the apatite layer is directly bonded to the bone. This AW
GC exceeds the mechanical strength of cortical bone and can be used as an artificial aggregate because it is strongly bonded to bone, and is considered to be used as an artificial bone such as an artificial vertebral body, an iliac spacer, and an artificial disc. However, since the mechanical strength is considerably lower than that of alumina or zirconia, the mechanical strength is insufficient for application to a joint portion or a high load portion.

[0004] Therefore, by combining the advantages of each of inert but high strength alumina and low strength but high bioactivity of hydroxyapatite, a biomaterial having bioactivity and high strength is obtained. For example, Japanese Patent Application Laid-Open No. 54-50 / 1979
As disclosed in Japanese Patent No. 194, there has already been proposed one in which a surface layer of a calcium phosphate-based material is applied to the surface of a high-strength substrate. In this case, the surface of the high-strength substrate is applied by a method such as plasma spraying a calcium phosphate material or soaking in a so-called slurry, and the thermal expansion coefficient of hydroxyapatite and the high-strength substrate is reduced. There was a problem that the difference was large and the adhesion to the substrate was extremely low.

On the other hand, as a method for improving the bonding strength to a substrate, Japanese Patent Laid-Open Publication No.
As disclosed in Japanese Patent No. 32675, a biological implant material in which a substrate is coated with a glass film and a calcium phosphate material film is formed through the glass layer has been proposed.

[0006]

However, although a bioimplant material formed with a calcium phosphate material film via the glass layer is an effective technique, it has been desired that the film strength be further improved in practical use. . That is, the glass film in the above technology has a small mechanical strength in a molten glass such as silica-based glass or calcium phosphate-based glass,
Particularly, in the past, the film thickness was about 1 mm, so that the film strength was sometimes insufficient for a high load. Further, since the calcium phosphate material film had a minimum thickness of 50 μm, there was a problem in the film strength.

[0007]

In order to solve the above-mentioned problems of the prior art, the present inventors have made intensive studies and found that the glass film was made of AWGC glass and the average film thickness was 10 to 10.
The thickness is controlled to 30 μm, and the film made of a calcium phosphate material such as hydroxyapatite is
It has been found that by controlling the thickness to μm, the adhesion strength can be increased and the film strength can be increased.

That is, the bioprosthesis member of the present invention comprises a ceramic substrate such as alumina, zirconia, or the like, and a calcium phosphate material formed on the surface of an apatite / wollastonite crystallized glass with an average film thickness of 10 to 30 μm. It is characterized in that a coating film having a thickness of 10 to 30 μm is formed.

When the average film thickness of the AWGC film is less than 10 μm, there is a possibility that the film is too thin to form a portion where no film is formed. On the other hand, if the average film thickness exceeds 30 μm, the strength may be reduced. When the average thickness of the film made of the calcium phosphate material is 10 μm or less,
There is a possibility that a film may not be formed in some places because it is too thin.

As a method of forming these coating films, a method of immersing a substrate in a slurry containing a material powder is preferable. According to this method, the film thickness can be controlled to be small, and it is also easy to form the coating film in the holes provided in the base material. However, the present invention is not limited to such a coating method, and a film may be formed by another coating method.

[0011]

To EXAMPLES Coating of calcium phosphate-based material to the Al ₂ O _3, as a binder a AWGC glass, hydroxyapatite (hereinafter, abbreviated as HAP) and Al ₂
After coating and firing on an O ₃ substrate, its physical properties were measured. The average thickness of the AWGC glass film was 20 μm, and the average thickness of the HAP film was 20 μm.

Implementation method (a) Al ₂ O ₃ substrate High-purity Al ₂ O ₃ (Af-1) fired plate (as-fire)
(B) AWGC glass CaCO ₃ 44.56 wt% SiO ₂ 27.29 wt% Ca ₂ P ₂ O ₇ 23.48 wt% MgO 3.53 wt% CaF ₂ 0.39 wt% CeO ₂ 0.09 wt% Room temperature to 1000 ° C. 2Hr heating 1000 ℃ × 2H
r 1000 ° C to 1480 ° C 5Hr temperature rise Pulverization Classification (63μm pass) (c) HAP purchased raw material → 900 ° C × 1Hr firing → wet pulverization (~ 48H
r) → Drying and sizing (average particle size: several μm) (d) Coating method ・ Coating method (1) Immerse Al ₂ O ₃ substrate in AWGC (10 wt%) solution and dry ↓ AWGC in HAP (10 wt%) solution Dip the coated sample, dry and bake at 900 ° C for 4 hours. ・ Coating method (2) Immerse Al ₂ O ₃ substrate in AWGC (10wt%) solution. Dry and bake at 900 ° C for 4Hr. ↓ AWGC coated sample on HAP (10wt%) solution. After immersion, drying and baking at 900 ° C. for 4 hours, the crystal structure of the surface of the test piece obtained by the above-mentioned coating method (1) or (2) was measured by an X-ray diffraction apparatus, the surface was observed by SEM, and EPMA was performed. Al, Ca, Si
Was observed. Further, the vertical section of the test piece was
And the distribution of Al, Ca and Si was observed by EPMA. The results were as follows.

(A) Crystal Structure of Surface Both coating methods (1) and (2) are HAP, Al ₂ O ₃ ,
A TCP peak was observed, and the peak of the HAP was sharper than when the HAP-AWGC glass mixture was coated, indicating that a large amount of HAP was present on the surface.

(B) Observation of Surface In the coating method (1), distribution of Si was observed on the surface of the coat film, indicating that AWGC was present on the surface of the coat layer.

In the coating method (2), no Si distribution was observed on the surface of the coat film, indicating that AWGC was not present on the surface of the coat film.

(C) Observation of cross section In the coating method (1), a gap was observed between the Al ₂ O ₃ substrate and the AWGC film, but in the coating method (2), such a gap was not observed. On the other hand, in both coating methods, there was a slight gap between the AWGC film and the HAP film.

EXPERIMENTAL EXAMPLE 1 With respect to the coating method (2) in the above method, the average film thickness was controlled by controlling the dipping time in the slurry (AWGC film = 20 μm,
HAP film = 20 μm) and product A: AWGC film = 30 μm /
HAP film = 20 μm, B product: AWGC film = 35 μm / H
AP film = 20 μm, C product: AWGC film = 10 μm / HA
P film = 30 μm, D product: AWGC film = 20 μm / HAP
Film = 35 μm, E product: AWGC film = 30 μm / HAP film = 20 μm, F product: AWGC film = 35 μm / HAP film =
20 μm was prepared.

With respect to these samples, the coating surface was scratched with a stainless steel pin, and the peeling of the film and the destruction of the film were observed. As a result, the above-mentioned example product, product A, product C
No peeling or film destruction was observed for the product and E product, but peeling and film destruction were confirmed for the remaining B product, D product and F product.

From these results, it was found that each of the AWGC film and the HAP film was preferably 30 μm or less.

[0020]

As described above, in the bioprosthesis member of the present invention, the glass film as the intermediate film is made of AWGC glass, the average film thickness is controlled to 10 to 30 μm, and the calcium phosphate material such as hydroxyapatite is used. By controlling the film thickness to an average film thickness of 10 to 30 μm, both the adhesion strength to the ceramic substrate such as alumina and zirconia and the film strength are high and have bone affinity.

[0021] Therefore, it is possible to provide a living body prosthetic material which has high mechanical strength, is highly compatible with the living body, and is stable and excellent in the living body without the calcium phosphate material peeling off and falling off from the substrate.

Claims (1)

[Claims] 1. A coating having an average thickness of 10 to 30 .mu.m made of a calcium phosphate material via a film of an average thickness of 10 to 30 .mu.m made of apatite / wollastonite crystallized glass on the surface of a ceramic substrate such as alumina or zirconia. A bioprosthesis member formed with a membrane.