JPH0657243B2 - Medical or dental curable composition - Google Patents

Description

TECHNICAL FIELD The present invention relates to a medical or dental curable composition.
More specifically, it is applied to a defective portion or void of bone or tooth caused by a pathological or external cause to facilitate the generation of new bone or tooth at the relevant portion, and then to the bone tissue or tooth tissue of the living body. The present invention relates to a curable composition capable of forming an integrated composite of an inorganic material and an organic material.

BACKGROUND ART Conventionally, as a dental cement composition, zinc phosphate cement, zinc oxide-polycarboxylate cement, glass ionomer cement, etc. have been developed, and further, resin cement using a methacrylate polymer as a bio-filling material. The material has been used. However, since these cement compositions are chemically different from tooth and bone components, they cannot be said to be sufficient in terms of biocompatibility. In order to solve these problems, ceramic-based materials having relatively good affinity with living bodies have been proposed. For example, an artificial bone made of a single crystal of Al ₂ O ₃ or a sintered body, an artificial joint or an artificial tooth root, an artificial bone made of a sintered body of hydroxyapatite, an artificial tooth root, or the like has been proposed. However, although these sintered bodies are suitable for use as implant materials, they have the drawback that they cannot be used as fillers or adhesives for bones, tooth defects and voids.

Recently, α- having a composition similar to that of the main components of bones and teeth
Cement compositions utilizing tricalcium phosphate powder have been proposed. For example, a method of adding a very small amount of an inorganic or organic acid to a kneaded product of α-tricalcium phosphate powder and water to obtain a cured product is known (for example, JP-A-59).
-182263).

However, in the above-mentioned known technique, the disintegration rate of the cured product is abnormally high, and the compression strength of the cured product is 50 kg / cm ²
It was as low as below, and there was a problem that the required performance as a medical or dental cement was not satisfied.

On the other hand, the present invention previously proposed a medical or dental curable composition for obtaining a cured product having excellent fluidity, high compressive strength and X-ray contrast (Japanese Patent Application No. 61-66795).
issue).

However, as a result of subsequent examination, it was found that the composition had some difficulties in solubility in water (disintegration rate).

Problems to be Solved by the Invention As described above, the requirements for the medical or dental cement composition are biocompatibility, low disintegration rate, and required compressive strength. Further, when filling a defective portion of a bone or a tooth, it is also an important requirement to have X-ray contrast property.

However, as described above, the composition proposed hitherto is
There have been problems such as insufficient biocompatibility and those having excellent biocompatibility, such as insufficient disintegration rate and compressive strength. Therefore, development of a cement composition which can be used as an artificial bone or an artificial tooth material in the field and is excellent in the above-mentioned various characteristics is desired.

The object of the present invention is to solve the above problems of the prior art,
It is an object of the present invention to provide a curable composition for medical or dental use which is excellent in biocompatibility, has a low disintegration rate, has a high compressive strength, and can obtain a cured product having an X-ray contrast property.

Means for Solving the Problems The present inventors have conducted various studies in order to solve the above problems.
As a result of the examination, a mixed powder of α-tricalcium phosphate powder and barium sulfate powder, using a mixture of an aqueous solution of citric acid and an aqueous solution of an unsaturated carboxylic acid homopolymer or copolymer as a kneading solution However, they have found that it is extremely effective for solving the above-mentioned problems, and have completed the present invention.

That is, the present invention provides (1) a powder component consisting of α-tricalcium phosphate powder and barium sulfate powder, and (2) a homopolymer or copolymer aqueous solution of an unsaturated carboxylic acid having a concentration of 30 to 55% by weight, and Concentration 30-55% by weight
And a curable composition for medical or dental use, which comprises an aqueous solution of citric acid and has a solid content mixing ratio of 1/9 to 9/1.

The α-tricalcium phosphate used in the composition of the present invention can be produced by a known method, for example, the following method.

That is, γ-calcium pyrophosphate and calcium carbonate are uniformly mixed in equimolar amounts, and after sufficiently drying, 1000
˜1400 ° C., preferably around 1300 ° C. for about 1 to 2 hours, and finely pulverize the resulting product to a particle size of 100 μm.
It can be obtained by using the following fine powder.

Alternatively, the α-tricalcium phosphate powder obtained as described above may be compressed by a rubber pressing method or the like and then fired again to obtain a fine powder. In the pressure compression treatment, the pressure is preferably 300 to 1200 kg / cm ² . In this way, the baking and pulverization treatments are performed twice. First, α-tricalcium phosphate is formed in the first treatment, and then the second operation is performed to improve the density, thereby compressing. It is intended to increase strength. However, it goes without saying that even the product obtained by the first firing and pulverization functions sufficiently as a component of the cement composition of the present invention.

On the other hand, the concentration of the citric acid aqueous solution used as the kneading solution is 30
Is in the range of up to 55% by weight. That is, when the concentration of the aqueous citric acid solution is less than 30% by weight, the compression strength of the cured product is low and it is not preferable as a cement material. Further, if the concentration of the aqueous citric acid solution exceeds 55% by weight, citric acid will precipitate, which is not preferable.

The other unsaturated carboxylic acid homopolymer or copolymer is preferably at least one selected from the group consisting of polyacrylic acid, or acrylic acid and methacrylic acid, maleic acid, fumaric acid, and itaconic acid. It is composed of a copolymer with an unsaturated carboxylic acid and can be produced by any known method. The concentration of these aqueous solutions is in the range of 30 to 55% by weight. If the concentration of the aqueous solution is less than 30% by weight,
The cured product has a low compressive strength and is not preferable as a cement material, and when the concentration of the aqueous solution exceeds 55% by weight, it tends to become difficult to dissolve, which is not preferable.

The mixing ratio of the solid content of the aqueous citric acid solution to the aqueous solution of the unsaturated carboxylic acid homopolymer or copolymer is 1: 9 to 9: 1 by weight, and particularly 3: 7 to 7: 3.
Is preferred. When the mixing ratio is changed, the characteristics of the cured product change subtly. That is, the compression strength of a cured product obtained by kneading α-tricalcium phosphate only with an aqueous citric acid solution is very high, which is preferable, but the disintegration rate is poor. Further, the disintegration rate of a cured product obtained by kneading α-tricalcium phosphate only with an aqueous solution of a polymer or copolymer of unsaturated carboxylic acid is preferable, but the compressive strength is rather low. Specifically, when kneading is performed only with a citric acid aqueous solution having a concentration of 46% by weight, the powder-liquid ratio (P / L ratio) is 2.5 and the compressive strength is 1800 kg.
/ Cm ² and becomes, decay rates indicates a 4.8% and a high value. When only a copolymer aqueous solution of acrylic acid and itaconic acid having a concentration of 45% by weight is kneaded, the disintegration rate is 3.0% at a P / L ratio of 1.5, which is a relatively low value. Is 800
It shows a value as low as kg / cm ² . The present invention provides a new curing liquid by mixing the aqueous solution of citric acid as described above and the aqueous solution of the homopolymer or copolymer of unsaturated carboxylic acid, and complements the drawbacks of both aqueous solutions.

As the barium sulfate powder to be added to the α-tricalcium phosphate powder, a commercially available barium sulfate powder can be used without any problem, and the amount used is
30% by weight or less based on α-tricalcium phosphate powder,
It is preferably used in an amount of 5% by weight or more, more preferably 10 to 20% by weight. If the addition amount of the barium sulfate powder exceeds 30% by weight, the compression strength of the cured product tends to decrease, which is not preferable.

Further, in the composition of the present invention, polymerization of a mixture (P) of α-tricalcium phosphate powder and barium sulfate powder, and a mixed aqueous solution (L) of a homopolymer or copolymer of an unsaturated carboxylic acid and citric acid. The mixing ratio (powder / liquid ratio), that is, P / L is preferably in the range of 0.5 to 2.5. The range of P / L = 1 to 2 is particularly preferable.

When P / L is less than 0.5 in the above ratio,
Since the amount of powder is small and the amount of water is excessive, the strength of the cured product is low, and conversely, when P / L is more than 2.5, the amount of water is too small and kneading becomes extremely difficult. .

The kneading operation method of the curable composition of the present invention is not particularly limited,
Any method conventionally used in the field of dental cement may be used, and for example, the method defined in JIS-6602 can be used.

Operation As already mentioned repeatedly, what is important for medical and dental cement compositions is biocompatibility, and in this respect, the composition of the present invention is chemically similar to bone and tooth components in α-
The use of tricalcium phosphate solves this problem.

By the way, Driskell is Ca (PO ₃ ) ₂ and Ca ₂ (PO
₄ ) ₂ (β-TCP) porous ceramics have been reported to be rapidly absorbed and bone-replaced after implantation, and McCoy and others have reported that β-TCP-containing porous ceramics
It was reported that the bone was replaced with autologous bone after 6 months of implantation in the calvaria of a rabbit. "Fine Ceramics Hand Blocks", pp. 425 (edited by Hamano, February 1984)
Please refer to "Asakura Shoten, 10th of March".

Further, shortening of the curing time and improvement of compressive strength are also important. This is because a mixed aqueous solution of an unsaturated carboxylic acid homopolymer or copolymer and citric acid is selected as a kneading solution, and the above α- It is solved by using it in combination with tricalcium phosphate.

Further, improvement of kneading workability and X-ray contrast property is also important, and this can be improved by adding barium sulfate powder to α-tricalcium phosphate. Thus, the combination of the present invention yielded an extremely excellent medical or dental composition, and its physical properties such as curing time, workability and compressive strength were remarkably improved as compared with conventional products of this type. .

Therefore, the curable composition of the present invention is advantageous for application to bone and tooth defects and voids caused by pathological or external causes, etc. It can be said that this is a composite material that can be expected to be integrated.

Examples The curable composition of the present invention will be described below in more detail with reference to Examples and the effects of the composition will be demonstrated, but the scope of the present invention is not limited thereto.

Examples 1 and 2 [gamma] -calcium pyrophosphate and calcium carbonate were calcined by a known method to synthesize [alpha] -tricalcium phosphate, crushed and passed through a 300 mesh sieve, and [alpha] -calcium phosphate powder having a predetermined particle size. Got

The α-tricalcium phosphate powder thus obtained was mixed with barium sulfate powder in the proportions shown in Table 1 below, and then mixed with JI.
The mixture was kneaded with the following kneading liquid according to the method of ST-6602.

(Kneading liquid) acrylic acid-itaconic acid copolymer (itaconic acid content 3
0% by weight) 26 parts by weight, citric acid 23 parts by weight and water 5
A mixed aqueous solution containing 1 part by weight was used as a kneading solution.

The fluidity of the kneaded product thus obtained, the compressive strength after 24 hours,
The results of measuring the X-ray contrast property and the disintegration rate are shown in Table 1. Incidentally, the X-ray contrast property and the fluidity were respectively determined as follows.

(I) X-ray contrast property: 80 KV20 on a cured product with a thickness of 2.5 mm
An X-ray of 0 mA was irradiated for 0.02 seconds to expose the X-ray film for comparison.

(Ii) Flowability: 0.5 ml of the kneaded cement composition was placed on a glass plate, and 3 minutes after the start of kneading, a glass plate weighing 20 g was placed on this, and a 100 g weight was placed on it. Put. After 10 minutes from the start of kneading, the average value of the maximum diameter and the minimum diameter of the spread sample was obtained, and this was used as a measure of fluidity.

Comparative Example 1 The powder of α-tricalcium phosphate obtained in Example 1 was kneaded with a 46 wt% aqueous solution of citric acid at a powder / liquid ratio of 2.5. The results of measuring the physical properties of the thus-obtained kneaded product in the same manner as in Example 1 are also shown in Table 1.

As is clear from the above results, the addition of BaSO ₄ improved the fluidity of the kneaded product, improved the workability, and significantly reduced the disintegration rate, and at the same time exhibited the X-ray contrast property.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yasuhito Tanaka 1352-80 Shibusawa, Hadano City, Kanagawa Prefecture (72) Inventor Kazuo Oyama 706-1 Shibusawa, Hadano City, Kanagawa Prefecture Inventor Osamu Matsuda Kohoku, Kanagawa Prefecture 3-7-14, Tarumachi, Ku (56) References JP 62-211069 (JP, A) JP 62-217969 (JP, A)

Claims (3)

[Claims] 1. A powder component comprising (1) α-tricalcium phosphate powder and barium sulfate powder, and (2) an aqueous solution and concentration of a homopolymer or copolymer of an unsaturated carboxylic acid having a concentration of 30 to 55% by weight. 30-55% by weight
A medical or dental curable composition comprising: an aqueous solution of citric acid and a mixed aqueous solution having a solid content mixing ratio of 1/9 to 9/1. 2. The unsaturated carboxylic acid homopolymer or copolymer is polyacrylic acid or at least one selected from the group consisting of acrylic acid and methacrylic acid, maleic acid, fumaric acid and itaconic acid. The curable composition for medical or dental use according to claim 1, which is a copolymer with the unsaturated carboxylic acid. 3. The curable composition for medical or dental use according to claim 1, wherein the barium sulfate powder is added in an amount of 5 to 30% by weight based on the α-tricalcium phosphate powder.