JPH04244161A - Biological material and manufacture thereof - Google Patents

Abstract

PURPOSE:To provide a vital implant material suitable as pros-thesis/repair alternative material of a root and a bone by achieving excellence in mechanical strength, affinity to an organism, reliability in handling and reliability in prolonged use. CONSTITUTION:A coating of a calcium phosphate based crystallized glass containing an apatite crystal is applied on a metal base material made of a titanium allow by a plasma metal coating.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a biological implant material and a method for producing the same.

0002

[Prior art] As an alternative material for tooth root and bone prosthesis and restoration,
Metal materials such as stainless steel, nickel-chromium alloy, cobalt-chromium alloy, titanium, and titanium alloy, and ceramic materials such as polycrystalline and single-crystal alumina, hydroxide apatite, bioglass, and crystallized glass are known.

[0003] Such biological implant materials are required to bond strongly with biological hard tissues such as teeth and bones, and to maintain high strength over a long period of time. However, although metal materials have high mechanical strength, they have a poor affinity with living organisms, so they do not have sufficient adhesion to living organisms, and they also have the disadvantage that metal ions may elute and harm living organisms. there were. Further, although the ceramic materials described above have a high affinity for living organisms, they have a problem in terms of mechanical strength and reliability.

[0004] In order to solve the above problems and obtain a material with high strength and high biocompatibility, a method is known in which a metal is used as a core material and the surface is coated with hydroxyapatite or bioglass (for example, Japanese Patent Publication No. 53-145394
, JP-A-52-82893, JP-A-58-109049
, Japanese Patent Publication No. 63-31654). However, the materials obtained by the above method do not have sufficient interfacial bonding strength between the metal core material and the surface ceramic material, and the surface ceramic layer itself has low strength, so it is easily damaged during handling and cannot be used for a long time. There is also the issue of poor reliability.

[0005]

[Problems to be Solved by the Invention] The purpose of the present invention is to solve the above-mentioned problems that the prior art had, and it is an object of the present invention to solve the above-mentioned problems that the prior art had. We propose a biological implant material coated with crystallized glass.

[0006]

[Means for Solving the Problems] The present invention provides a biological material characterized by coating a metal substrate with crystallized glass containing biocompatible apatite crystals. The present invention also provides a method for producing a biological material, which comprises forming a glass layer on a metal substrate by plasma spraying, and then heat-treating the plasma-sprayed glass layer to form crystallized glass. It is something to do.

[0007] The metal base material in the present invention is selected from titanium, titanium alloy, stainless steel, chromium-cobalt alloy, nickel-chromium alloy, etc., which are stable in the living body and less susceptible to damage. Titanium alloys are most preferred because they are the most stable and have the highest strength.

[0008] Furthermore, the crystallized glass containing biocompatible apatite crystals in the present invention refers to P2O5, CaO
, SiO2, and apatite is precipitated by crystallization treatment at 1000° C. or lower, but wollastonite or witrockite crystals may be precipitated at the same time. Furthermore, it may contain Al2O3, TiO2, Na2O, etc. in order to control biological activity.

[0009] The crystallized glass composition preferably contains Ca
O 14-61, P2O5 7-37, SiO2
12-50, Na2O 0-20, Al2O3 0
-10, TiO2 0-10 (all units are wt%)
).

The reasons for limiting the glass composition will be explained below. If CaO is less than 14%, the amount of apatite crystals precipitated from the glass will be too small, which is undesirable;
% or more is not preferable because the glass tends to devitrify. It is not preferable that P2O5 is less than 7% or more than 37% because the amount of apatite crystals precipitated from the glass decreases. If the SiO2 content is less than 12%, the glass tends to devitrify, and if it exceeds 50%, the viscosity of the glass becomes high and melting becomes difficult, so both are not preferred.

[0011] Na2O, Al2O3, and TiO2 may be included in order to control the bioactivity of crystallized glass, but if Na2O exceeds 20%, the amount of apatite crystals precipitated from the glass will be too small, which is not preferable. In addition, Al2O3 and TiO2 each have 10
%, it is not preferable because the amount of apatite crystals precipitated from the glass decreases and the degree of biological activity decreases significantly.

[0012] The intermediate glass in the present invention is a crystallized glass composed of the same type of components as the outermost layer bioactive crystallized glass, and its expansion coefficient is different from that of the metal base material and the outermost layer bioactive crystallized glass. Moreover, its chemical durability is greater than that of the outermost bioactive crystallized glass.

[0013] The outermost layer of crystallized glass becomes crystallized glass containing apatite and wollastonite by heat treatment at 1000°C or less, and is chemically bonded firmly to bone within 8 weeks in vivo. The crystallized glass of the intermediate layer has a smaller amount of apatite precipitated by the same heat treatment than the crystallized glass of the outermost layer.

By using a specific crystallized glass as a material for coating a metal substrate, there is an advantage that the bioactivity can be controlled by the crystallization treatment conditions without being affected by the coating conditions. ,
Since it can be heat treated at a lower temperature than hydroxide apatite, it has the advantage of suppressing the deterioration of metal materials, especially titanium alloys, by heat treatment. In addition, crystallized glass itself,
Since it is a material with higher strength than sintered hydroxyapatite or bioglass, it is possible to make high-strength composite materials.

[0015] The biological material of the present invention is preferably produced essentially by plasma spraying. Plasma spraying is a known film forming method that is extremely effective in forming a ceramic film with a thickness of several tens to several hundred micrometers and a strong initial adhesion force. As a result of researching the above-mentioned plasma spraying method for crystallized glass, the present inventors discovered a method for creating the above-mentioned multilayer crystallized glass layer in a single plasma spraying process, and obtained the obtained product in this way. We found that the resulting biomaterial has high biocompatibility and great mechanical strength.

That is, one of the methods is to form a bioactive crystallized glass layer on a metal substrate by plasma spraying, by using the same glass raw material and changing the plasma spraying conditions. This manufacturing method is characterized by changing the coefficient of thermal expansion of the metal substrate and continuously forming an intermediate glass layer and a surface crystallized glass layer on a metal base material.

The present inventors have discovered that when coating calcium phosphate glass on a metal substrate by plasma spraying, the ratio of P2O5/SiO2 in the composition of the sprayed glass layer decreases as the spraying temperature increases. I found it. As the ratio of P2O5/SiO2 decreases, the thermal expansion coefficient of the glass decreases and the chemical durability improves.

Therefore, when performing plasma spraying on a metal substrate using the same glass raw material, by gradually or stepwise lowering the spraying temperature, the thermal expansion of the glass layer in contact with the metal substrate can be reduced. It is possible to reduce the coefficient, improve chemical durability, and make the outermost glass layer a glass with high bioactivity. This method is particularly effective when plasma spraying onto titanium alloys. This is because the coefficient of thermal expansion of titanium alloy is 90 to 95 x 10-7/°C, whereas the coefficient of thermal expansion of calcium phosphate crystallized glass, which has high bioactivity, is 100 to 130 x 10-
This is because the temperature is as large as 7/℃.

Another manufacturing method is to prepare a glass raw material for the intermediate glass layer and a glass raw material for the surface crystallized glass layer, which have different component ratios, first spray the intermediate glass onto the metal substrate, and then spray the intermediate glass onto the metal substrate. The glass for the glass layer and the glass for the surface crystallized glass are thermally sprayed simultaneously while changing the mixing ratio so that the ratio of the glass for the surface crystallized glass changes gradually, and the final surface layer consists only of the surface crystallized glass. This manufacturing method is characterized by forming a glass layer like this. The reason why this method can increase the bonding strength between the metal base material and the outermost crystallized glass layer having high bioactivity is clear from the above.

[0020] By these methods, it is possible to obtain biomaterials having high biocompatibility and high mechanical strength. In the present invention, the plasma spraying conditions can be continuously changed depending on the gas component ratio in the chamber and the substrate temperature.

[0021]

EXAMPLE Various materials shown in Table 1 were plasma sprayed onto the end face of a titanium alloy with a diameter of 20 mm to form a sprayed coating layer with a thickness of about 150 μm. Afterwards, in an argon atmosphere,
Heat treatment for crystallization was performed at 0° C. for 1 hour. After heat treatment, an adhesive was applied to the surface of the sprayed coating layer, a stainless steel jig of the same shape as the sprayed base material was attached, and a tensile test was performed at room temperature in the atmosphere at a crosshead speed of 1 mm/min.
The adhesive strength between the sprayed base material and the coating layer was measured.

[0022]

[Table 1]

[0023] In addition, a sample was thermally sprayed and heat-treated on a titanium alloy plate under the same conditions, and then immersed in a simulated biological fluid kept at 37°C for 30 days, and after being taken out, the composition and crystals on the sample surface were analyzed. The bioactivity of the sample was evaluated by comparing it with that before immersion.

Table 2 lists the evaluation results of the adhesive strength and biological activity of the plasma sprayed layers prepared under various conditions to the sprayed base material.

[0025]

[Table 2]

The detailed plasma spraying conditions in Table 2 will be explained below. Thermal spraying condition (a) is to thermally spray 50 μm of biological glass 2 onto a titanium alloy, and then apply biological glass 2 and biological glass 1 on top of it at the same time, gradually increasing the ratio of biological glass 1. A sprayed layer with a thickness of 50 μm was formed by gradually changing the spraying ratio, and on top of that,
Only biological glass 1 was thermally sprayed to a thickness of 50 μm. For all plasma spraying, the outer peripheral temperature of the plasma flame is approximately 2000℃.
It was carried out by low temperature thermal spraying.

[0027] Thermal spraying condition (b) is that biological glass 1 is coated on titanium alloy at an outer peripheral temperature of the plasma flame of approximately 5000°C.
The glass was thermally sprayed to a thickness of 80 μm using high-temperature spraying, and on top of that, biological glass 1 was thermally sprayed to a thickness of 70 μm using low-temperature spraying.

Thermal spraying conditions (c) were as follows: Living body glass 1 was sprayed onto a titanium alloy to a thickness of 150 μm by low-temperature spraying.

Thermal spraying condition (d) is to spray 80 μm of ordinary glass (sample (3)) onto the titanium alloy, and then
Biological glass 1 was thermally sprayed to a thickness of 70 μm. All plasma spraying was performed at low temperature.

[0030] Thermal spraying condition (e) is that synthetic hydroxyapatite (sample (4)) is sprayed onto the titanium alloy at a low temperature of 150%.
μm sprayed.

[0031]Thermal spraying conditions (c) and thermal spraying conditions (d)
, The thermal spraying condition (e) is a comparative example.

From the results in Table 2, it is clear that the thermal spray coating layer produced by the method of the present invention firmly adheres to the metal base material, and
It can be seen that it exhibits biological activity.

[0033]

According to the present invention, it is possible to obtain a composite material in which the surface of a metal core material is coated with bioactive crystallized glass that is firmly bonded to metal. The material has high strength and high biocompatibility, and thus can be used as a bioimplant material.

Claims (7)

[Claims] 1. A biological material comprising a metal substrate coated with calcium phosphate crystallized glass containing biocompatible apatite crystals. 2. A biological material having an intermediate glass layer on a metal substrate, and a calcium phosphate crystallized glass layer containing biocompatible apatite crystals on the intermediate glass layer. 3. The intermediate glass layer is made of calcium phosphate-based crystallized glass, and the thermal expansion coefficient of the intermediate glass layer is between the thermal expansion coefficient of the metal base material and the thermal expansion coefficient of the surface crystallized glass. The biological material according to claim 2, characterized in that: 4. Claim 2, wherein the intermediate glass layer is made of calcium phosphate crystallized glass, and the chemical durability of the intermediate glass layer is superior to that of the surface crystallized glass. biomaterials. 5. Production of a biological material, characterized in that an intermediate glass layer and a surface glass layer are formed on a metal substrate by plasma spraying, and then heat treatment is performed to convert the plasma sprayed glass layer into crystallized glass. Method. 6. By changing the plasma spraying conditions using the same glass raw material, the thermal expansion coefficient of the glass layer to be formed is changed, and the intermediate glass layer and the surface crystallized glass layer are continuously coated with a metal base. 6. The method for producing a biological material according to claim 5, wherein the method is formed on a material. 7. A glass raw material for the intermediate glass layer and a glass raw material for the surface crystallized glass layer are prepared, and the intermediate glass is first thermally sprayed onto the metal substrate, and then the glass for the intermediate glass layer and the surface crystallized glass are sprayed. It is characterized by the fact that both materials are thermally sprayed at the same time while changing the mixing ratio so that the ratio with the glass for use in glass gradually changes, forming a glass layer in which the final surface layer consists only of the surface crystallized glass. The method for producing a biological material according to claim 5.