JP2000060957A - Implant material for organism and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the mechanical strength, quicken the binding to the bone and make keepable the stability over a long period of time by forming a coat having a titania phase and an alkali titanate phase on a titanium-base metal base plate surface and making calcium carbonate crystal adhere to the coat. SOLUTION: A base material is formed by use of a titanium alloy obtained by adding Na, Mg, P and so on to pure titanium. The coat having a titania phase and an alkali titanate phase is formed on the surface thereof. A titania gel phase or an alkali titanate gel phase may exist. A calcium carbonate crystal is made adhere to the upper surface of the coat. A calcium titanate crystal may exist. The alkali titanate phase in the coat is replaced by hydronium ions in a body fluid to become a titania gel phase, so that the body fluid pH is raised to easily deposit apatite. calcium carbonate crystal adsorbs phosphoric acid ions and calcium ions. Thus, apatite can be formed in a short time.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a bioimplant material and a method for producing the same.

[0002]

2. Description of the Related Art Conventionally, various bioimplant materials have been proposed as substitute materials for bone. For example, high-strength materials such as stainless alloys and titanium-based metals such as titanium and titanium alloys, and bioactive materials such as apatite sintered bodies, bioactive glass, and bioactive crystallized glass are known.

High-strength materials such as stainless alloys and titanium-based metals have high mechanical strength, but require a long period of time to bond with bone. Further, bioactive materials such as apatite sintered body, bioactive glass, and bioactive crystallized glass are bound to bone in a short period of time, but their strength is insufficient and their application sites are limited. Therefore, an implant material in which a coating made of a bioactive material is formed on the surface of a high-strength material by plasma spraying or baking has also been proposed.However, even in this material, the base material and the coating are formed during long-term implantation in the living body. Peeling may occur at the interface of.

Therefore, the present applicant has filed Japanese Patent Application No. 8-357040.
Proposes an implant material in which a coating film made of a titania phase or an alkali titanate phase is formed on the surface of a base material made of a titanium-based metal, and calcium ions are contained in the coating film.

[0005]

In the above-mentioned materials, the coating is formed integrally with the base material and has bioactivity, so that the coating does not peel off even after bonding with natural bone. However, this material requires a long postoperative rest period due to its slow bond speed with natural bone.

An object of the present invention is to provide a bioimplant material which has high mechanical strength, is capable of binding to bone in a short period of time, and is stable in vivo for a long period of time, and a method for producing the same.

[0007]

The bioimplant material of the present invention comprises a titanium metal-based substrate surface on which a coating having a titania phase and an alkali titanate phase is formed, and calcium carbonate crystals are formed on the coating. It is characterized by being adhered.

Further, in the method for producing a bioimplant material of the present invention, a base material made of a titanium-based metal is immersed in an alkaline solution, baked, and then immersed in a calcium hydroxide solution in an atmosphere containing carbon dioxide. It is characterized by

[0009]

In the bioimplant material of the present invention, the titanium-based metal constituting the base material is pure titanium or N
a, Mg, P, Nb, Zr, Al, Sn, Pt, Ta,
A titanium alloy with V added can be used.

The film formed on the surface of the substrate has a titania phase and an alkali titanate phase. In addition to these, there may be a titania gel phase or an alkali titanate gel phase.

Calcium carbonate crystals adhere to the coating film. Also, calcium titanate crystals may be present.

When the implant material of the present invention having the above characteristics is brought into contact with a body fluid, alkali ions in the alkaline titanate phase or alkaline titanate gel phase in the coating film are exchanged with hydronium ions in the body fluid to form a titania gel phase, The ion exchange also raises the pH of the body fluid near the implant material, creating an environment in which apatite easily precipitates. On the other hand, the calcium carbonate crystals existing on the coating film serve as seeds to adsorb calcium ions in the body fluid. Further, phosphate ions are adsorbed in an attempt to maintain electrical neutrality. In this way, bone-like apatite is rapidly formed on the surface of the coating, and it is early bound to bone through this layer.

Next, a method for producing the bioimplant material of the present invention will be described.

First, a titanium-based metal is formed into a desired shape to prepare a base material.

Next, the base material is dipped in an alkaline solution.
A thin film of titania is usually present on the surface of the titanium-based metal, and when they are brought into contact with an alkaline solution, these react with each other to form an alkaline titanate gel. Titania gel may also be formed. In this way, a coating having a titania phase or a titania gel phase and an alkali titanate gel phase is integrally formed on the surface of the base material. As the alkaline solution, an aqueous solution of sodium hydroxide, potassium hydroxide or the like is used. Conditions such as the concentration, temperature, and immersion time of the alkaline solution may be determined according to the degree of formation of the film on the material surface, but the concentration is 2 to 10 mol / l, and the temperature of the solution is 25.
Appropriate dipping time is 12 to 48 hours at ˜90 ° C.

Subsequently, the substrate is fired to transform a part or the whole of the alkali titanate gel into a stable alkali titanate to enhance the stability of the film. The firing condition is 200
It is desirable that the transition temperature of the substrate is within 4 hours.

Thereafter, when the base material is immersed in a calcium hydroxide solution in an atmosphere such as the atmosphere where carbon dioxide is present, carbon dioxide in the atmosphere reacts with the calcium hydroxide solution to produce calcium carbonate crystals, This adheres to the coating surface of the substrate. Further, if the calcium hydroxide solution has high reactivity, it may react with the coating film on the substrate to form calcium titanate on the coating surface. An aqueous solution of calcium hydroxide can be used as the calcium hydroxide solution. The concentration of calcium hydroxide solution is 0.1
-20 Mmol / l, especially 5-20 Mmol / l are preferred. If the concentration is lower than 0.1 Mmol / l, it becomes difficult to generate calcium carbonate crystals, and if it is higher than 20 Mmol / l, the amount of calcium carbonate crystals is excessively generated, film peeling or cracking occurs, and a strong bond with bone is obtained. It will be difficult. The liquid temperature of the calcium hydroxide solution is 50 to 150.
It is preferably in the range of 100 ° C., particularly 100 to 140 ° C. If the liquid temperature is lower than 50 ° C, it becomes difficult to generate calcium carbonate crystals, and if it exceeds 150 ° C, the amount of calcium carbonate crystals is excessively increased. The treatment time may be appropriately adjusted depending on the concentration of the solution and the temperature of the solution, but it is suitable to perform the treatment within a range of 10 minutes to 3 days.

[0018]

EXAMPLES The present invention will be described below based on examples.

Table 1 shows examples of the present invention (Sample Nos. 1 to 1).
3) and a comparative example (sample No. 4) are shown.

[0020]

[Table 1]

Each sample was prepared as follows.

First, a pure titanium plate having a size of 10 × 10 × 1 mm was prepared as a base material. Then, the substrate is 5 mol /
It was immersed in 5 ml of an aqueous NaOH solution (60 ° C.) for 24 hours, washed with pure water, and dried to form a film composed of a titania phase and a sodium titanate gel phase on the surface of the base material. Then, the base material was baked at 600 ° C. for 1 hour to change a part of the sodium titanate gel phase to the sodium titanate phase. Then, the sample was obtained by immersing it in 5 ml of an aqueous calcium hydroxide solution or an aqueous calcium chloride solution in the air under the conditions shown in the table, washing with pure water, and drying. Where 1
When the temperature was lower than 00 ° C, the treatment was carried out in a constant temperature bath, and when the temperature was 100 ° C or higher, the treatment was carried out in an autoclave.

With respect to the obtained sample, it was confirmed by thin film X-ray diffraction whether or not calcium carbonate crystals were formed. Also, each sample was immersed in a simulated body fluid prepared to the same ion concentration as the body fluid, and the period required for forming the apatite layer was investigated,
The rate of binding to bone was evaluated. The results are shown in Table 1.

As is apparent from the table, N which is a comparative example.
o. In the sample of No. 4, no calcium carbonate crystals were observed on the surface of the coating film, and it took 120 hours to generate apatite. In the samples 1 to 3, calcium carbonate crystals were present on the surface of the coating film, and as a result, apatite was produced in a short time of 12 to 24 hours.

[0025]

INDUSTRIAL APPLICABILITY The bioimplant material of the present invention has a high mechanical strength because the base material is made of titanium metal. Moreover, since a bone-like apatite layer is formed early on the capsule, it is combined with bone in a short period of time. Moreover, the coating is formed integrally with the base material, is stable in the living body for a long period of time, and is promising as a bioimplant material.

Further, according to the manufacturing method of the present invention, the above-mentioned bioimplant material can be easily manufactured.

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Claims (5)

[Claims] 1. A bioimplant material characterized in that a coating having a titania phase and an alkali titanate phase is formed on the surface of a base material made of a titanium-based metal, and calcium carbonate crystals adhere to the coating. . 2. A method for producing a bioimplant material, which comprises immersing a substrate made of a titanium-based metal in an alkaline solution, firing the substrate, and then immersing the substrate in a calcium hydroxide solution in an atmosphere containing carbon dioxide. Method. 3. The method for producing a bioimplant material according to claim 2, wherein an aqueous calcium hydroxide solution is used as the calcium hydroxide solution. 4. The method for producing a bioimplant material according to claim 2, wherein a calcium hydroxide solution having a liquid temperature of 50 to 150 ° C. is used. 5. A calcium hydroxide solution having a concentration of 0.1 to 20 Mmol / l is used.
The manufacturing method of the bioimplant material of (4).