JPS61186247A - Crystallized cao-al2o3-p2o5 glass - Google Patents

Abstract

PURPOSE:To obtain a three-component crystallized glass having low internal defects and suitable as dental materials and artificial bone materials, etc., by compounding CaO, Al2O3 and P2O5 at specific ratios. CONSTITUTION:The objective glass is obtained by mixing 10-60wt% CaO, 5-25wt% Al2O3 and 25-85wt% P2O5. It can be produced by (1) selecting one or more compounds from each of Ca-containing compounds, P-containing compounds and Al-containing compounds and mixing the components so s to attain the above glass composition, (2) mixing the components throughly with each other and melting by heating at about 1,000-1,700 deg.C, (3) cooling and vitrifying the mixture, and finally (4) properly heat-treating (e.g. at about 600-1,100 deg.C) the glass produced in the step 3.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a medical material containing calcium phosphate crystals, which is most suitable as a dental material, an artificial bone material, etc.

[Conventional technology]

In recent years, the range of applications for ceramics has expanded rapidly, reaching the medical field, and efforts are now being made to apply ceramics to medical materials, such as artificial tooth roots, for which metals and plastics have traditionally been used. .

The present inventors searched for a ceramic material that has an affinity for living organisms, and as a result of repeated research into a method for manufacturing high-strength ceramic by freely and highly precisely molding it into any shape, they found that a calcium phosphate-based material was used as a raw material. We have discovered that this is possible by selecting the appropriate method, and have been conducting extensive research on it.

[Problem that the invention seeks to solve]

Even with calcium phosphate materials that have these excellent characteristics, once they are vitrified and crystallized, internal defects occur due to the difference in specific gravity between the glass and the crystals, resulting in a decrease in mechanical strength and the infiltration of bacteria. It becomes easier.

For example, the atomic ratio of calcium and phosphorus Ca/Pca0
．． The specific gravity of No. 48 calcium phosphate glass is 2.63, and when it is heat-treated and crystallized, CaO.P2O5 is generated. The true specific gravity of this CaO・P2O5 crystal is 2.8
5, which is considerably larger than the specific gravity of glass. However, since crystallization proceeds by a surface devitrification mechanism, there is almost no decrease in volume accompanying crystallization, so as the specific gravity increases due to crystallization, voids corresponding to the increase in specific gravity are generated inside the crystal, and the crystallization - Internal defects such as vines and boas. Because of these internal defects, the strength of the crystal is lower than that of a crystal without defects. In addition, since the atomization of borefish depends on various factors such as the atomic ratio of calcium and phosphorus in the crow, crystallization temperature, and crystallization time, large variations in mechanical strength can be avoided. I can't.

Even when crystallization is performed by the bulk crystallization mechanism, which involves adding additives or devising the crystallization method, these internal defects are larger than those caused by the volume shrinkage of crystallization or the surface devitrification mechanism. Although the degree of occurrence is small, it still happens in the same way.

[Means for solving problems]

In order to eliminate the above-mentioned drawbacks, it is better to eliminate the difference in specific gravity before and after crystallization, and the present inventors have developed a method that does not impair the biocompatibility of calcium phosphate and the characteristics of no volume contraction during crystallization. As a result of various studies on methods that do not cause internal defects, we succeeded in solving the above problem by adopting a three-component crystallized glass (CaO-Al2O3P2O1), and completed the present invention. be.

[Action] In the composition of the CaO-Al2O3P2O5 3-component system, C
aO10-60% by weight, Al2O35-25% by weight, P
The range is 20625 to 85% by weight.

When this glass is crystallized, the crystals produced are, for example, CaO.P2O5, 2Ca○.P2O5, and Al2O3.P2O5, and their true specific gravity is 2.85, 3.09, and 2.09, respectively. It is 59,
Since the specific gravity of Al2O3/P2O5 is considerably lower than that of other calcium phosphate crystals, if it is mixed with other calcium phosphate crystals, internal defects such as bores will not occur in the crystal.

For example, a glass with a composition of 21.8% by weight of Ca, 9.3% by weight of Al2O, and 68.9% by weight of P2Os has a specific gravity of 2.64, and when this glass is crystallized, its specific gravity is 2.67. However, the volume shrinkage during crystallization is approximately 0.
．． 5%, the bore volume is approximately 0.6%, and internal defects are reduced to an almost negligible level.

The above-mentioned effects due to the formation of Al2O3.P2O5 crystals are similar even when calcium phosphate-based crystals other than the above-mentioned calcium phosphate-based crystals are generated.

[Structure of the invention]

The starting materials of the present invention are calcium-containing compounds that produce CaO when fired, such as calcium oxide, calcium hydroxide, calcium carbonate, and calcium oxalate, and phosphorus-containing compounds that produce phosphorus oxides when fired, such as phosphoric acid and polyphosphoric acid. Compounds and aluminum-containing compounds such as alumina and aluminum hydroxide that become aluminum oxide when fired are used. Also, calcium phosphate, apatites, aluminum phosphate, calcium aluminate, etc. can be used.

Select one type or two or more of each of a calcium-containing compound, a phosphorus-containing compound, and an aluminum-containing compound,
The composition of the glass is 10 to 6% by weight of CaO, Al2O35
-25% by weight, P2o525-85% by weight.

If CaO is more than 60% by weight or P 2 O s is less than 25% by weight, the melting temperature will be high and glass will not form. Conversely, less than 10% by weight of CaO or P 2 O s 85
If it exceeds % by weight, the melting temperature decreases and vitrification becomes easy, but the crystallization process becomes difficult and excessive phosphoric acid is liberated, making it chemically unstable, which is not preferable. On the other hand, if the alumina content exceeds 25% by weight, the melting temperature will become high, and if it is less than 5% by weight, Al2O3・P2
This is also undesirable because O5 crystals are not produced or the amount produced is small, and the occurrence of internal defects such as bores cannot be prevented.

The calcium phosphate glass of the present invention basically consists of Ca,
It is composed of three components, AI and P, but when using the crystallized glass produced by the method of the present invention as a dental material, a colorant component is added to give it exactly the same color as natural teeth. You can also do that. This colorant component interacts with the calcium phosphate component to develop color, and the color tone can be subtly adjusted by changing the type, combination, and amount of the colorant components. When adding colorant components, Zn, Fe, Mn, W, Ce, Ti,
Ni.

It is one type or two or more types selected from oxides of Co, Cr, and V, and a combination of two or more types is particularly preferable. The amount added is about 15 parts by weight per 100 parts by weight of the CaO-Al2O3P2O5 ternary oxide.

The raw materials are weighed, mixed well, placed in a container, and heated to 90,000 C or more, preferably 1,000 to 17,006 C to melt. Care must be taken when melting at temperatures above 1800°C, as evaporation of the phosphorus component begins.

After the melting is completed, it is cooled and vitrified. Subsequently, it is melted and cast again, but the first melt may be directly cast without being cooled and vitrified. CaO-Al2O3- of the present invention
In the case of materials based on P2O5 components, the lost wax method used for casting metal dental materials is suitable because the viscosity of the melt can be kept sufficiently low. The preheating temperature of the casting mold is 8006C or less, preferably 2O0~
The temperature is appropriately selected within the range of 800°C depending on the material of the casting mold and the composition of the glass.

The casting thus cast is glassy. By applying appropriate heat treatment to this glassy material to make it crystallized glass, the properties can be further improved. The method for crystallizing the three-component crystallized glass according to the present invention is as follows. A molded body formed by a lost wax method or the like is heated in a suitable heating device such as an electric furnace.

The heating temperature at this time is below the melting point, preferably 60°C.
It is 0 to 11006C.

〔Example〕

Example 1 Calcium carbonate powder, alumina powder, and orthophosphoric acid were weighed so that the final composition was 21.8% by weight of Ca, 9.3% by weight of Al2O3, and 68.9% by weight of P2Os, and after thorough kneading, platinum was added. lhr at 1400°C in crucible
It was melted, cast into a size of 3x4x30mm, and cooled and vitrified. The obtained calcium phosphate glass was heated in an electric furnace for 7
The temperature was maintained at 10°C, 11C118O, and crystallized.

The obtained crystallized glass is white and semi-transparent, and its three-point bending strength is 1850 to 2000 kg/cm, with an average of 1
It was 900 kg/cTIX2. According to the results of X-ray diffraction of the crystal, CaClP2O5 and Al2 are present in the crystal.
O3/P2O5 was present. Also, the specific gravity of glass is 2.6
4. The specific gravity of the crystal was 2.67, which was a small difference, and when the microstructure of the crystal was observed under a microscope, no internal defects such as bores were found.

Comparative Example 1 Calcium carbonate powder, alumina powder, and orthophosphoric acid were weighed so that the final composition was 26.5% by weight of Ca, 2.9% by weight of Al2O, and 70.6% by weight of P2Os, and the same procedure as in Example 1 was carried out. Melted, cast, crystallized.

The obtained crystallization strength glass was also white and semi-transparent, but its three-point bending strength was 50 to 12 ook kg/c2, which was also smaller than that of Example 1.

According to the results of X-ray diffraction of the crystal, CaO is present in the crystal.
- Only P2O5 was observed, and Al2O3/P2O5 was not present. The specific gravity of the glass was 2.67, and the specific gravity measured by crushing the crystal was 2.80, and approximately 4 to 5% of bores were present in the crystal.

〔Effect of the invention〕

As seen in the examples, CaO7Al2O3 of the present invention
In P2O6 crystallized glass, the volumetric shrinkage during crystallization of calcium phosphate crystals is compensated for by the production of Al2O3 and P2O5 during crystallization, so the difference in specific gravity before and after crystallization is small, so It has no internal defects and has very good mechanical strength, making it ideal as a biomaterial for artificial tooth crowns and artificial bones.

Claims (1)

[Claims] A CaO-Al_2O_3-P_2O_5-based crystallized glass characterized by comprising 10 to 60% by weight of CaO, 35 to 25% by weight of Al_2O_, and 525 to 85% by weight of P_2O_5.