JPS63252913A - Hardenable material - Google Patents

Abstract

PURPOSE:To obtain a hardenable material, consisting essentially of specific fluorine-containing self-hardenable calcium phosphate and having biocompatibility and crushing strength and useful as a dental cement. CONSTITUTION:A hardenable material obtained by firing a blend of a phosphorus compound, such as Ca(H2PO4)2.H2O or CaHPO4, with a calcium compound, such as CaO, Ca(OH)2 or Ca(COO)2, and a fluorine compound, such as CaF2 or NH4F, at 700-1,400 deg.C for 1-10hr to provide a fluorine-containing self- hardenable calcium phosphate (A), containing Ca and P at 1.4-1.6g atomic ratio (Ca/P) and F and P at 0.01-0.33g atomic ratio (F/P) and having 6/1-1/100 intensity ratio of the peak at 30.7+ or -0.2 deg. (2theta) to that at 31.9+ or -0.2 deg. (2theta) measured by X-ray diffractometry and blending >=40wt.% component (A) with a fluoride, such as an amine fluoride, (C) 2X10<-5>-1.2X10<-3>mol./g hardening accelerator (e.g. lactic acid) and (D) a powdery substance (e.g. silica).

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a curable material having self-curing properties.

More specifically, the present invention relates to a curable material that forms a cured fluoroapatite body, such as a biomaterial for biological substitutes and fillings, particularly useful as an oral cavity material.

(Prior art) The theoretical formula for calcium-phosphorus apatite (hereinafter referred to simply as apatite), which is a type of calcium phosphate, is Ca (P 04) 6 X
2 (X represents an anion such as OH-, C1-, F-O, etc.). Here, the gram atom ratio of Ca/P is theoretically lO/6=1.67, but
In fact, it is said that an apatite structure can be formed with a Ca/P ratio in the range of 1.3 to 2.0. Therefore, various general formulas have been proposed, such as Ca1O-x(H2O2)x(PO4)6-x X2-
It is shown as x.

This apatite is the main component of the aga component of teeth and bones,
Since it has excellent in-vivo compatibility and is easily assimilated into living tissues, attempts have been made to use apatite sintered bodies as biomaterials such as artificial tooth roots. Furthermore, in recent years, various methods have been proposed for obtaining biomaterials such as dental restorative materials using self-hardening calcium phosphate that can be converted into apatite in the oral cavity or in vivo.

(Problems to be Solved by the Invention) In Japanese Patent Application No. 61-240851, the present inventors also calculated calcium and phosphorus using the Durham atom ratio (:a/P=1.
We have proposed a curable material consisting of hydrated self-curing calcium phosphate contained in a ratio of 3 to 2.0, a fluoride that is sparingly soluble in water, an acid, and wood. According to the invention of the same application, an oxidized apatite can be generated in a relatively short period of time near the body temperature, and the Knoop hardness of the resulting cured product is 12 to 15 kg/am2 immediately after curing compared to the conventional technology. A cured product with much higher hardness can be obtained compared to the conventional method. Moreover, this cured product has little shrinkage during curing,
Furthermore, even if the cured product is stored in water or artificial saliva after hardening, it is stable; in particular, when stored in artificial saliva, the Knoop hardness increases over time, and in some cases, the hardness increases up to 40 kg/am2 after 30 days of oral administration. It has been obtained.

However, for applications such as dental restorative materials, even higher levels of physical properties are required, such as crush resistance when the cured product is stored in artificial saliva.

(Means for solving the problem) As a result of repeated studies based on the above background, the present inventors have found that when blending fluorine atoms into calcium phosphate, the fluorine atoms are observed as microscopically as possible to make them more uniform. In comparison with the cured material obtained by the invention previously proposed by the 11 undeveloped parties, when a curable material mainly composed of fluorine-containing self-curing calcium phosphate obtained by mixing it in calcium phosphate is hydrated and cured, Furthermore, it was discovered that a cured product with high strength could be obtained, and based on this knowledge, the present invention was completed.

That is, the present invention contains calcium and phosphorus in a duram atom ratio of Ca/P=1.4 to 1.6, and further contains fluorine in a duram atom ratio of F/p=Q,
Fluorine containing at a ratio of ot ~ 0.33 and the intensity ratio of the peaks at 20 or 30.7 ± 0.2 degrees and 31.9 ± 0.2 degrees by x6 diffraction is 6/1 to 1/100. The present invention provides a curable material mainly composed of self-curing calcium phosphate.

The fluorine-containing self-hardening calcium phosphate used in the present invention satisfies the above Ca/P and F/P ratios, and also has a 2θ of 30.7 ± 0.2 degrees and 31.
The peak intensity ratio at 9±0.2 degrees is 6/1 to 1/1
00.

When calcium phosphate with a Ca/P ratio outside the range of 1.4 to 1.6 is used, it takes a long time to cure even if a curing accelerator described below is used, and the cured product still exhibits the curing of the present invention. In addition, the F/P ratio must be in the range of 0.01 to 0.33, preferably in the range of O,OS to 0.25. F/P ratio 0. The effect of the present invention is hardly seen when the fluorine content is lower than that of O1;
Addition of a large amount of fluorine with a P ratio exceeding 0.33 does not increase the effect of the present invention. The reason for this can be considered as follows.

That is, the cured product of the present invention forms fluorinated apatite after being cured. The theoretical formula for fluorinated apatite is Ca 10 (P O
4) 6 F 2, and F/P=2/6=0.33. Therefore, it is thought that even if a large amount of fluorine is added such that the F/P ratio exceeds 0.33, fluorine becomes excessive in the cured product.

The fluorine-containing self-hardening calcium phosphate used in the present invention has a 2θ of 30.7±0.2 degrees (α-Ca
3(corresponding to the main peak of PO2)2) and 31.9±0.2
It has two peaks at 50°C (corresponding to the main peak of Calo(P04)6Fz), and the intensity ratio of the peaks is 6/1 to 1/100. In other words, the appearance is good, and the fluorine-containing self-hardening calcium phosphate is α-Ca.
3(P O4)2 and Caro (P O,s )
It is thought that the main component is a mixed crystal of a F z. A method for preparing such fluorine-containing self-hardening calcium phosphate is to prepare calcined a Ca :l (P O4)Z and Ca
to (P O4) 6 F 2 may be prepared separately and then intimately mixed using, for example, a ball mill or a laikai machine, or reacted mechanochemically. In the fluorine-containing calcium phosphate obtained here, the fluorine atoms in it are microscopically distributed as uniformly as possible, and in some cases, it is better that the fluorine atoms are uniformly distributed at the molecular level or crystal lattice level. Preferred for achieving the purpose of the invention.

Therefore, C so that the above Ca / P and F / P become
a (H2PO4)2-Hz0. CaHPO4, CaH
PO4・2H20, Ca2P2O7゜Ca H(P
O) ・5 Hz O1Ca (PO)OH
(However, phosphorus compounds such as
03 ) 2, organic acid calcium 11! Calcium compounds such as CaF, NH4F)IF
.

It is more preferable to prepare by blending a fluorine compound such as NH4F and firing the mixture.

That is, the fluorine-containing self-hardening calcium phosphate used in the present invention is obtained by baking the formulation described in 1 at a temperature of 700°C to 1400°C, preferably 900°C to 1300°C, for about 1 hour to 10 hours, preferably about 2 hours to 4 hours. However, if calcium phosphate calcined under conditions outside the above range is used, the curing speed will be slow and this is not so preferred.

The curable material of the present invention preferably contains 40 fii% or more of this fluorine-containing self-curing calcium phosphate.

The curable material of the present invention essentially hydrates and hardens when mixed with water. It is preferable to use an organic or inorganic acid as a curing accelerator in order to allow this curing reaction to proceed in a relatively short period of time near the body temperature.

Organic acids used in the practice of the present invention include tetraformic acid, acetic acid,
Lower-basic fatty acids such as propionic acid; hydroxycarboxylic acids such as malic acid, glycolic acid, lactic acid, citric acid, sugar acid, and ascorbic acid; acidic amino acids such as glutamic acid and aspartic acid: oxalic acid, malonic acid, succinic acid, and geltaric acid .

21 such as adipic acid, maleic acid, fumaric acid, muconic acid, etc.
1! Base acids; keto acids such as pyruvic acid, acetoacetic acid, and levulinic acid; aromatic carboxylic acids such as salicylic acid, benzoic acid, cinnamic acid, and phthalic acid; and their salts such as alkali metal, alkaline earth metal, or ammonium salts; Derivatives of the above-mentioned aerobic acids that easily generate carboxylic acid groups by hydrolysis include acid anhydrides, acid chlorides, and the like.

In addition, examples of inorganic acids include phosphoric acid, chlorinated acid, nitric acid, sulfuric acid, and their salts such as alkali metal, alkaline earth metal, or ammonium salts. Among these, organic acids are particularly preferred.

These acids have the effect of shortening the curing time and increasing the hardness of the curable material of the present invention. If the curing speed is too long or too short, problems will arise in practical operability. Therefore, it is preferable to control the curing time depending on the purpose of use. The curing time of the curable material of the present invention can be varied from several minutes to several hours by adjusting the amount of acid added and its pH. Specifically, it varies depending on the type of acid used, but the amount of acid used in combination with self-curing calcium phosphate is about 2xlO-5■ol/g ~ 1.2X
It is generally used within the range of 10-3 sol/g. In addition, the pH of the acid is preferably in the range of 2.0 to 6.0, especially 3.0 when it is made into a 1 mol aqueous solution.
~5.0 is convenient.

Further, in the curable material of the present invention, inorganic and organic fluorides such as metal fluorides, ammonium fluorides, and amine fluorites may be used in combination with the self-curing fluorine-containing calcium phosphate. When used in combination with the self-curing calcium phosphate contained therein, additional effects such as accelerating the curing rate of the curable material, increasing dimensional stability during curing, and increasing hardness can be obtained. When these fluorides are used together, it is preferable that the total fluorine content and total phosphorus content in the curable material be at most gram atom ratio F/P=0.33.

Fluorides that can be used in the present invention include potassium fluoride, magnesium fluoride, beryllium fluoride, strontium fluoride, barium fluoride, titanium fluoride, cobalt fluoride, tin fluoride, aluminum fluoride, and fluoride. Metal fluorides such as sodium chloride, lithium fluoride, potassium fluoride, cesium fluoride, ferrous fluoride, ferric fluoride, rubidium fluoride, ammonium fluoride, acidic ammonium fluoride, cetylamine hydrochloride, Examples include fluorides of ammonia and amines such as jetanolaminopropyl-N-ethanoloctadecylamine-dihydrofluoride.

Furthermore, the curable material of the present invention mainly contains the above-mentioned fluorine-containing self-hardening calcium phosphate, and in addition to fluoride and acid as a hardening accelerator, powder materials useful as aggregates, such as silica powder, and apatite, which does not have self-hardening properties, are used. Of course, it is also possible to further adjust the various physical properties of the hardened body by further using powder, pulverized apatite sintered body, etc.

As mentioned above, when the 3rd r&minutes related to the fluorine-containing self-curing calcium phosphate are used together, the curable material contains at least 40% by weight of the above-mentioned specific fluorine-containing self-curing calcium phosphate. Preferably.

The curable material of the present invention is composed of a combination of the above-mentioned components and has a powder-like appearance.

The practical way to use it is to mix it with an appropriate amount of water and harden it, but as mentioned above, in practice it is preferable to use acids as hardening accelerators, depending on the curable material used and the acids. It is also possible to prepare each separately and mix them together when kneading with water. In particular, if the acid is in powder form, it is convenient to prepare the curable material and the acid in powder form beforehand. It is recommended to mix by adding only water.

In addition, if the acid is soluble in water, a method may be used in which the curable material of the present invention and the acid aqueous solution are prepared in advance and kneaded before use. This is representative, but of course not limited to this.

The weight ratio of the powder component and liquid component is 10.0:
2.0 to O:5. It is preferable to mix and use them at a ratio of o.

If the liquid component is less than this, the fluidity of the kneaded mixture of the powder component and the liquid component will be insufficient and it will be difficult to mold it into the desired shape, and if it is more than this, the fluidity of the kneaded product will be excessive. This makes it difficult to maintain a specific shape, both of which are undesirable.

(Significance and Effects of the Invention) By hydrating and curing the curable material of the present invention by an appropriate means, a cured body of fluorinated apatite with high strength can be formed. The fluorine-containing self-curing calcium phosphate used in the curable material of the present invention contains fluorine atoms, and moreover, the fluorine atoms are microscopically dispersed extremely uniformly in the calcium phosphate. be.

Comparing the case where such fluorine-containing self-curing calcium phosphate is used and the case where fluorine-free self-curing calcium phosphate is used and fluoride is separately added and mixed, in both cases, when hydrated and cured, fluoride is removed. The common feature is that a hardened apatite product can be obtained. However, in the case of the former (the present invention), a cured product with higher strength can be obtained than in the latter. As is clear from the results of the Examples and Comparative Examples described below, the results of the Examples corresponding to the former are superior to the results of the Comparative Examples corresponding to the latter in terms of crushing drag and Knoop hardness. In particular, when the hardened material is stored in artificial saliva, the crushing resistance increases dramatically.The hardened material using the curable material according to the method of the present invention retains the excellent biocompatibility characteristic of apatite, and In terms of crushing strength, a much higher value can be obtained than when fluoride is added and mixed with self-hardening calcium phosphate. Therefore, it can be said that the curable material of the present invention is extremely useful especially for dental cement and the like.

(Example) Next, the present invention will be explained in more detail based on examples.

Example 1 CaHPO27.2gt eaC038.5g.

A mixture obtained by thoroughly mixing 39 g of Ca F z O in a mortar (about 30 minutes) was baked at 1200° C. for 2 hours to obtain fluorine-containing self-hardening calcium phosphate.

When this calcium phosphate was analyzed, Ca/P=
A result of 1,45, F/P=0.05 was obtained. Further, X-ray diffraction was performed under the following conditions. As a result, the diffraction intensity ratio (XRD) of 20 at 30.7 degrees and 32.0 degrees was about 471.

X-ray diffraction measurement conditions Anticathode Cu Filter Ni Excitation voltage 30Kv Current 15■＾ Count cost Full imperial scale 2000c/s time constant
1 sec Scanning speed 2°/haze Chart speed 20 nm/sin Divergence angle
l.

Light reception slit 0.15 ■■ For the above lucium phosphate Ig, 1 mol citric acid solution (adjusted to pH 3.0 with ammonia water) 0.2
10m! was added and thoroughly kneaded. The coagulation time of the obtained kneaded product was measured according to JIS T 6604. The curing time was defined as the time required until the Vicat needle no longer left a mark. As a result, the setting time was 8 minutes and the curing time was 42 minutes. The hardness after 24 hours of curing was Knoop hardness 19 kg/-12. Furthermore, the crushing resistance of this kneaded product was measured according to JIS 76602. The result was 121 kg/-1.

Furthermore, the cured product was stored in the following artificial saliva kept at 37°C, and changes in Knoop hardness and crushing resistance were observed. As a result, the Knoop hardness after 45 days was 35 kg/am2. The crushing force after 140 mm was 735 kg/mm''.

These results are shown in Table 1 below.

Artificial saliva liquid A ammonium chloride (NH4FHF) 0-
466g potassium chloride (KCl) 2.
124g monopotassium phosphate (KH2PO,)
0.708gNa5(C611207)2H200,0
208g208g Phosphorus II NazllP 04
0, 750g urea (N11□)2Go
Dissolve 0.346g in water to make a monomer.

B solution Calcium chloride dihydrate (CaCtan2211□0)
0.420g Magnesium chloride (MgCJl2) 0.0
Dissolve 4g in water to make 1i.

At the time of use, liquid A and liquid B are mixed at a volume ratio of 1:1.

Example 2 Ca2P2O725.4g, CaCO38.7g, Ca
9g of F z O in a mortar for about 30 minutes
The mixture obtained by mixing was baked at 1200° C. for 2 hours. Table 1 shows the X-ray diffraction intensity ratio of the obtained fluorine-containing self-curing calcium phosphate. For this fluorine-containing self-hardening calcium phosphate Ig, 1 lol citric acid solution (
However, adjust the pH to 5.0 with ammonia water) o, zts
mg was added and thoroughly kneaded. The above calcium phosphate and kneaded product were analyzed and evaluated in the same manner as in Example 1 except for the above conditions, and the results are summarized in Table 1.

Example 3 1 g of powder obtained by mixing 4 g of fluorine-containing self-curing calcium phosphate prepared in Example 2 with 17 g of NH4FHFO was mixed with 0.20 g of the same citric acid solution used in Example 2.
1d was added and thoroughly kneaded. The obtained affinities were analyzed and evaluated in the same manner as in Example 1, and the results are summarized in Table 1.

Example 4 1 g of powder was obtained by uniformly mixing 8 g of fluorine-containing self-hardening calcium phosphate prepared in Example 2 with 2 g of a crushed apatite sintered product (#200 mesh complete) and 14 g of N)14FHFO. A citric acid solution in the 0.216 range was added to the mixture used in Example 2 and thoroughly kneaded. The obtained kneaded product was analyzed and evaluated in the same manner as in Example 1,
The results are summarized in Table 1.

Example 5 Ca2P20, 25.4 g, CaCO39.5 g, C
A mixture obtained by thoroughly mixing 1.17 g of aF 2 in a mortar (about 30 minutes) was fired at 1200° C. for 2 hours.

Table 1 shows the X-ray diffraction intensity ratio of the obtained calcium phosphate. 1 mol citric acid solution for this calcium phosphate Ig (however, the pH was adjusted to 5.0 with ammonia water)
o, zio suri was added and thoroughly kneaded. The above calcium phosphate and kneaded product were analyzed and evaluated in the same manner as in Example 1 except for the above conditions, and the results are summarized in Table 1.

Comparative Example 1 A mixture obtained by thoroughly mixing 7.2 g of Ca P O and 1 O g of CaCO in a mortar (about 30 minutes) was
The product was baked at 00°C for 2 hours to obtain self-hardening calcium phosphate. This calcium phosphate was subjected to X-ray diffraction under the same conditions as in Example 1. As a result, a strong diffraction peak appeared at 20-30.7 degrees, but no diffraction peak was observed at 32.0±0.2 degrees. Calcium phosphate as above,
7 for 1 g of powder obtained by thoroughly mixing 8 g of Ca F z I for 31 g in a mortar (about 30 minutes).
1 mol citric acid solution (pH 5 with ammonia water,
0.215d was added and thoroughly kneaded.

The obtained kneaded product was analyzed and evaluated in the same manner as in Example 1, and the results are summarized in Table 1.

Comparative Example 2 31 g of self-hardening calcium phosphate synthesized in Comparative Example 2
1.8 g of Ca F z and NH4F) (FO
, 57 g were uniformly mixed, and 0.216 d of the same citric acid solution as that used in Comparative Example 1 was added to 1 g of the powder and thoroughly kneaded. The obtained kneaded product was analyzed and evaluated in the same manner as in Example 1, and the results are summarized in Table 1.

Claims (1)

[Claims] 1) Calcium and phosphorus as gram atom ratio Ca/P
= 1.4 to 1.6, and the gram atom ratio of fluorine to phosphorus is F/P = 0.01 to 0.33.
2θ by X-ray diffraction is 30.7.
A curable material mainly composed of fluorine-containing self-curing calcium phosphate having a peak intensity ratio of 6/1 to 1/100 at ±0.2 degrees and 31.9±0.2 degrees.