JPS6212705A - Medical and dental cement composition - Google Patents

Abstract

PURPOSE:The titled composition having improved adaptability to organisms, a short curing time, high compression strength and a transparent feeling, obtained by blending an aqueous solution of citric acid with a specific concentration with tricalcium alpha-phosphate powder in a specific weight ratio. CONSTITUTION:In a medical or dental cement composition consisting of tricalcium alpha-phosphate powder and an aqueous solution of citric acid, a cement composition having 30-60wt%, especially 35-55wt% aqueous solution of citric acid and a weight ratio P/L of tricalcium alpha-phosphate powder (P) and the aqueous solution of citric acid (L) of 1.3-3, especially 2-2.5. The tricalcium alpha-phosphate is preferably treated by calcination and pulverizing twice.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to medical or dental cement compositions. More specifically, after application to bone or tooth defects or cavities caused by pathological or external causes, it will not integrate with the bone tissue or tooth tissue of the living body, and will not cause new bone formation in the area. The present invention relates to a composition that facilitates the generation and formation of teeth and forms a complex of a structural material and an anterior structural material. , Conventional technology Zinc phosphate cement, zinc oxide-polycarboxylate cement, glass ionomer cement, etc. have been developed as dental cement compositions, and methacrylate polymers etc. have been used as biofilling materials. Resin cement materials have been used. However, since all of these cement compositions are chemically different from the components of teeth and bones, they cannot be said to have sufficient biocompatibility.

Furthermore, in order to solve these problems, ceramic materials that have relatively good biocompatibility have been proposed. For example, artificial bones, artificial joints, and artificial tooth roots made of single crystals or sintered bodies of Al2O3, and artificial bones and artificial tooth roots made of sintered bodies of hydroxyapatite have been proposed. However, although these sintered bodies are suitable for use as implant materials, they have the disadvantage that they cannot be used as fillers or luting agents for bone, tooth defects, and cavities. .

Furthermore, recently, a cement composition using α-tricalcium phosphate powder having a composition similar to the main component of bones and teeth has been proposed. For example, a method is known in which a very small amount of inorganic or organic acid is added to a kneaded mixture of α-tricalcium phosphate powder and water to obtain a cured product (for example, JP-A No. 59-182263). (see official bulletin).

However, in the known technology, the curing time is 1
It takes more than 0 minutes, and the compressive strength of the obtained cured product is less than 50 kg / ci, which does not meet the required performance as a medical or dental cement. Moreover, the cured product has no transparency, so it is particularly difficult to prepare. There was a problem that it could not be used as dental cement.

Problems that Application I attempts to solve As mentioned above, the first requirement for a medical or dental cement composition is that it be biocompatible.
Furthermore, it is also important to have a predetermined curing speed and strength after curing, especially compressive strength.

Furthermore, when used as a dental material, there is a tendency for materials with excellent transparency to be preferred due to their beautiful appearance and good visibility, so the appearance after curing must be transparent. is preferred.

However, as mentioned above, the compositions proposed so far are
The biocompatibility was insufficient, and those with excellent biocompatibility were insufficient in terms of curing speed, compressive strength, etc., and the transparency was poor. Therefore, in this field, there is a long-awaited development of a cement composition that can be used as an artificial bone or artificial tooth root material and has excellent various properties as described above.

Therefore, the purpose of the present invention is to solve the problems of the conventional technology, have excellent biocompatibility, short curing time, and
An object of the present invention is to provide a medical or dental cement composition that has high compressive strength and can yield a cured product with a transparent appearance.

Means for Solving the Problems The inventors of the present invention have attempted to solve the above-mentioned problems by kneading a relatively high concentration citric acid aqueous solution into α-tricalcium phosphate powder. The present invention was completed based on the discovery that mixing as a liquid is extremely effective for solving the above problems.

That is, the medical or dental cement composition of the present invention is
A composition consisting of α-tricalcium phosphate powder and citric acid aqueous solution, the concentration of citric acid aqueous solution is 30 to 60% by weight, and α-tricalcium phosphate powder (P) and citric acid aqueous solution (L ) is characterized in that the weight ratio P/L is in the range of 1.3 to 3.

The α-tricalcium phosphate powder used in the present invention is generally obtained as follows.

For example, calcium hydrogen phosphate dihydrate (CaHPO
, 2 H2O) is dried and then heated at a temperature of about 300 to 500°C to form γ-calcium pyrophosphate (
r-Ca2P 20t) is obtained. Next, the T-calcium pyrophosphate and calcium carbonate were uniformly mixed in equimolar amounts, thoroughly dried, and then heated at 1000 to 1300°C.
The desired α-tricalcium phosphate powder can be obtained by calcining at a temperature of preferably around 1200°C for about 1 hour and pulverizing the resulting product into a fine powder with a particle size of 100 μm or less. .

Still another method is to uniformly mix calcium hydrogen phosphate dihydrate and calcium carbonate at a molar ratio of 2:1 and then sinter it under the same conditions as above to obtain the desired α-triphosphate. Calcium powder can be obtained.

Further, the α-tricalcium phosphate powder obtained as described above was compressed under pressure using a rubber press method, etc., and then
Calcinate at a temperature of 0 to 1,400°C, preferably 1,200 to 1,300°C for at least 1 hour, and similarly pulverize to obtain a particle size of 0.
．． It can also be made into a fine powder of about 5 to 2 OAtm. In the above pressure compression process, the pressure is 300 to 1200 kg.
/car is preferred.

The reason for performing the firing and pulverization treatment twice in this way is to first form α-tricalcium phosphate in the first treatment, and then to improve the density in the second operation, thereby compressing it. It is intended to increase the strength.It goes without saying that the product obtained by the first firing and pulverization can also function satisfactorily 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 was 30
It is necessary that the content is in the range of ~60% by weight, especially 35% by weight.
Preferably it is an aqueous solution with a concentration range of 55% by weight. That is, if the concentration of the citric acid aqueous solution is less than 30% by weight, the compressive strength of the cured product will be low (200 g /
cnf or less), the cured product loses its transparency, making it undesirable as a cement material. Conversely, if the concentration of the citric acid aqueous solution exceeds 60% by weight, citric acid will precipitate, making it practically unusable. Can not.

In addition, about 10% by weight or less of the citric acid in the above citric acid aqueous solution is added to tartaric acid, tannic acid, phytic acid, lactic acid or i
) It is also possible to replace it with a water-soluble acid such as phosphoric acid.

Furthermore, in the composition of the present invention, the weight mixing ratio of α-tricalcium phosphate powder (P) and citric acid aqueous solution (L) (
powder/liquid ratio), that is, P/L, is required to be in the range of 1.3 to 3. Particularly preferably, P/L is in the range of 2 to 2.5.

If P/L is less than 1.3 in the above ratio,
If the powder amount is small and the water content is excessive, the strength of the cured product will be low. Conversely, if P/L is greater than 3, the water content will be too small and kneading will become extremely difficult, which is not preferable.

The composition of the present invention uses citric acid as an aqueous solution to produce α-
In addition to the method of kneading with tricalcium phosphate powder, you can mix α-tricalcium phosphate powder and citric acid powder in advance and add water to this, or mix α-tricalcium phosphate powder and citric acid powder. It can also be produced by mixing a portion of the powder in advance and mixing the remaining citric acid with an aqueous solution in water.

However, in any of the above cases, it is necessary to adjust the amounts of α-tricalcium phosphate powder, citric acid, and water to fall within the above ranges.

As stated repeatedly, biocompatibility is important for medical, industrial, and dental cement compositions, and in this regard, the composition of the present invention uses α- The problem is solved by using tricalcium phosphate. It is also important to shorten curing time and improve compressive strength, which was solved by selecting a relatively high concentration citric acid aqueous solution as the kneading liquid and using it in combination with the above-mentioned α-tricalcium phosphate. Ta. Through the combination of the present invention, an extremely excellent cement composition was obtained, and its physical properties such as hardening time and compressive strength were significantly improved compared to conventional products of this type (see Examples below). ).

Therefore, the cement composition of the present invention is suitable for pathological or □
It is a composite material that is advantageous when applied to defects and voids in bones and teeth caused by external causes, and is expected to integrate with the bone composition and tooth tissue of the living body after application. I can say that.

EXAMPLES Below, the cement composition of the present invention will be explained in more detail with examples, and the effects of the composition will be demonstrated, but the scope of the present invention is not limited thereby.

Examples 1 to 8 α-tricalcium phosphate powder was produced as follows. Calcium hydrogen phosphate dihydrate (CaHP Oa
・2 H2O) 2 moles were placed in a magnetic crucible, and 500
℃ for 5 hours to produce γ-calcium pyrophosphate (γ-C
aw P 207), and then equimolar amounts of calcium carbonate were mixed homogeneously and then calcined at 1200° C. for 2 hours.

It was then taken out into the open air and quenched, and the resulting product was ground and passed through a 300 mesh sieve.

The obtained product (powder I) was analyzed by X-ray diffraction and confirmed to be α-tricalcium phosphate. The powder I was further pressurized and compressed at a pressure of 500 Kg/cnt, and then fired again at 1300 °C for 2 hours.
It was ground to obtain a powder (powder ■) of 5 to 20 μm.

Powder I and powder II obtained as above were mixed into J I
In accordance with the method of ST-6602, citric acid aqueous solutions of various concentrations listed in Table 1 were kneaded to achieve various powder-liquid ratios, and the curing time, compressive strength and transparency after 24 hours were measured. . The results are shown in Table 1.

Comparative Examples 1 to 8 Powder I and Powder II were kneaded with an aqueous solution of citric acid or acetic acid at the concentrations listed in Table 1 to achieve various powder-liquid ratios in the same manner as in the above examples, and measurements were performed.

The results are also shown in Table 1.

From the comparative test results shown in Table 1 above, when the citric acid aqueous solution concentration and powder/liquid ratio are within the range of the present invention, the curing time is short, the compressive strength is very high, and the curing is transparent. It became clear that something could be achieved.

On the other hand, in the case of the citric acid aqueous solution concentration outside the range of the present invention (Comparative Examples 1.2.3 and 6), the curing time was long, and especially the compressive strength of the cured product was significantly reduced. Furthermore, when the powder/liquid ratio was outside the range of the present invention (Comparative Examples 4 and 5), the compressive strength was low or kneading was impossible.

Furthermore, when acetic acid, which is an acid in an amount other than that used in the present invention, is used (Comparative Examples 7 and 8), satisfactory compressive strength and transparency cannot be obtained at low concentrations; It turns out that no cured product was obtained.

A summary of the above results is shown in a graph as shown in FIG.

In FIG. 1, curve A represents the composition according to the invention, P/
Line B shows the relationship between the citric acid aqueous solution concentration and compressive strength when L=2.0, and straight line B shows the relationship between the citric acid aqueous solution concentration and compressive strength when P/L=1.0 (outside the present invention). This shows that. As is clear from these graphs, when the powder-liquid ratio (P/L) is low, the compressive strength is extremely reduced, and when the concentration of the citric acid aqueous solution is less than 30% by weight or exceeds 60% by weight, has very low compressive strength.

In addition, Examples 1 and 3 show that the compressive strength is further improved by subjecting α-tricalcium phosphate, the main raw material of the composition of the present invention, to twice firing and fine powder treatment to improve the density. Alternatively, it can be understood by comparing the physical properties of the products obtained in 2 and 6, that it is advantageous to perform the firing and pulverization treatment twice for applications that require higher compressive strength.

Effects of the Invention As described in detail above, the medical or dental cement composition of the present invention has excellent biocompatibility, short curing time, and significantly higher compressive strength than conventional techniques. Moreover, it is possible to obtain a cured product with a transparent appearance.

Therefore, the cement composition of the present invention is extremely useful in the medical and dental fields.

[Brief explanation of the drawing]

FIG. 1 shows P/L=1. It is a figure showing the relationship between citric acid aqueous solution concentration and compressive strength in the case of O and P/L = 2.0.

Claims (4)

[Claims] (1) In a medical or dental cement composition consisting of α-tricalcium phosphate powder and a citric acid aqueous solution, the concentration of the citric acid aqueous solution is 30 to 60% by weight, and α
-Tricalcium phosphate powder (P) and citric acid aqueous solution (L)
) The above cement composition has a weight ratio P/L of 1.3 to 3. (2) The cement composition according to claim 1, wherein the concentration of the citric acid aqueous solution is in the range of 35 to 55% by weight. (3) The cement composition according to claim 1 or 2, wherein the α-tricalcium phosphate has been subjected to two firing and pulverization treatments. (4) The α-tricalcium phosphate powder and the citric acid aqueous solution can be prepared by mixing the α-tricalcium phosphate powder and citric acid powder in advance and adding water to the mixture, or by adding water to the mixture in advance. A patent claim characterized in that α-tricalcium phosphate powder and a portion of citric acid powder are mixed in advance, and an aqueous solution in which the remaining citric acid is dissolved in water is added to the mixture. The cement composition according to any one of the ranges 1 to 3.