JPH02153840A - Production of dental crystallized glass - Google Patents

Abstract

PURPOSE:To obtain dental crystallized glass capable of providing artificial teeth excellent in aesthetic properties, biocompatibility, strength, dimensional accuracy, etc., by melting a glass raw material of a specific composition, forming the raw material, heat-treating the formed material and depositing tetrasilicofluoromica-based crystals and calcium phosphate-based crystals. CONSTITUTION:A glass raw material is prepared so as to provide a glass having a composition within the range of 40-70wt.% SiO2, 3-7wt.% MgO, 8-17wt.% MgF2, 0-2wt.% Al2O3, 4-20wt.% K2O, 0.1-15wt.% total amount of ZrO2 and TiO2, 0.1-20wt.% CaO and 0.1-20wt.% P2O5. The prepared glass raw material is then heated, melted and formed and the formed body is subsequently heat- treated to deposit tetrasilicofluoromica-based crystals and calcium phosphate- based crystals and produce dental crystallized glass. Thereby, since production can be carried out by a casting method, artificial teeth of a high dimensional accuracy can be produced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to dental crystallized glass used for filling or prosthetic tooth structure that has been lost or deformed due to decay, trauma, etc., or for improving aesthetics. It is something.

[Prior Art J] Dental materials conventionally used to fill and restore missing or deformed tooth structure include alloys, amalgams, acrylic resins, porcelains, and combinations of these materials.

Dental materials are inert in the oral cavity, have good biocompatibility, can withstand masticatory forces, can be formed into shapes with high dimensional accuracy through a relatively simple manufacturing process, and are similar to natural teeth. Although aesthetic properties are required, there is currently no material that satisfies all of these conditions.

In other words, alloys and amalgams have poor aesthetics because their appearance differs from natural teeth, while acrylic polymers and porcelains have excellent aesthetics, but are weak in strength and often cannot withstand the forces of mastication. Composite structures made by combining these materials, such as metal-fired porcelain, can withstand chewing forces and have good aesthetics, but they may have harmful effects and require advanced technology to manufacture. required.

Further, in recent years, in the field of dental treatment, crystallized glass has attracted attention as a dental material to replace the above-mentioned materials, and various dental crystallized glasses have been proposed to date. Currently proposed dental crystallized glasses are broadly divided into two systems: one that precipitates mica-based crystals as disclosed in JP-A-5L199742; Calcium phosphate crystals such as apatite crystals as disclosed in Japanese Patent No. 63-10939 are precipitated.

[Problems to be solved by the invention] Dental crystallized glass, which can be divided into two systems, generally has the same aesthetic properties as natural teeth and can be molded into various shapes. However, each has its advantages and disadvantages. In other words, crystallized glass that precipitates mica-based crystals is not brittle, can withstand point impact, and does not propagate fracture, but it has relatively poor biocompatibility and poor dimensional accuracy. In addition, crystallized glass, which precipitates calcium phosphate crystals, has excellent biocompatibility with gingival tissues, etc., but its strength is relatively weak.
In particular, there is a drawback that the strength deteriorates significantly due to scratches.

The purpose of the present invention is to create a dental crystallized material that satisfies all the characteristics required of a source-fertilized dental material, and in particular has excellent biocompatibility and high mechanical strength, which were not possessed by conventional dental crystallized glass. An object of the present invention is to provide a method for manufacturing glass.

Means for Solving Problem E] As a result of various studies, the present inventors have strictly regulated the mixing ratio of each glass raw material, melted it, formed it, and heat-treated it to form a glass material. It has been discovered that it is possible to produce crystallized glass having excellent biocompatibility and high mechanical strength by precipitating desired amounts of fluoromica tetrasilicide crystals and calcium phosphate crystals.

That is, the method for producing dental crystallized glass of the present invention includes SiO□ 40.0-70.0%, JO3゜0-7.8%, MgF 28.0-17.0%, Al2O
, 0-2.0%, 20 4.0-20.0%, zro
□+ Ti0z 0.1-15.0%, Ca0 0.1
``Fluoromica tetrasilicide crystals and calcium phosphate crystals are precipitated by melting glass raw materials in the range of 20.0%, p2o, o, t ~ 20.0%, molding, and heat treatment. Features.

The reason why the amount of glass raw materials is limited as described above in the method for producing dental crystallized glass of the present invention is as follows.

5i02 is a tetrasilicated fluoromica crystal <KMg2.
5Si40+oFz) and is a component that improves the strength of the glass matrix phase.
If it is less than 70.0%, the glass will be easily softened and deformed when it is heat-treated for crystallization, and if it is more than 70.0%, it will be difficult to melt the glass and it will be difficult to obtain a uniform glass.

MgO is a constituent component of fluoromica tetrasilicide crystals, but if it is less than 3.0%, the amount of fluoromica tetrasilicide crystals precipitated will be extremely small, resulting in significant deterioration in strength against scratches. %, enstatite crystals (MgOS i
03) etc. are precipitated, the glass becomes cloudy and the aesthetics deteriorate.

MgF2 is a constituent component of fluoromica tetrasilicide crystals, but if it is less than 8.0%, the amount of fluoromica tetrasilicide crystals precipitated will be extremely small, resulting in a large deterioration in strength against scratches. %, the glass tends to be softened and deformed during the crystallization heat treatment.

A1□03 is a component that stabilizes calcium phosphate crystals and improves their chemical durability, but if the amount exceeds 2.0%, iolide crystals (Mg2AI4SiqO+s), which are foreign crystals, may be produced when glass is heat-treated for crystallization. is undesirable because it tends to precipitate. That is, when iolide crystals precipitate, the glass becomes cloudy, resulting in poor aesthetics and an excessively high hardness.

K2O is a component of tetrasilicated fluoromica crystals, but if it is less than 4.0%, foreign crystals such as enstatite crystals will precipitate, resulting in cloudy glass and poor aesthetics. %, coarse mica-based crystals will precipitate during the crystallization heat treatment of the glass, making it difficult to obtain a uniform glass.

ZrO2 and TiO2 are components that control the size of tetrasilicated fluoromica crystals, but if it is less than 0.1%, this effect cannot be obtained, and if it is more than 15.0%, enstatite crystals etc. Due to the precipitation of foreign crystals, the glass becomes cloudy and the aesthetics deteriorate.

CaO and P2O5 are constituent components of calcium phosphate crystals and are included to improve biocompatibility, and their content is 0.1 to 20.0% each. e
If aO and P2O5 are each less than 0.1%,
There is almost no precipitation of calcium phosphate crystals such as apatite crystals (Catn(PO,5)60) and tricalcium phosphate crystals (3CaOP205), resulting in poor biocompatibility, and if each exceeds 20.0%, the glass may devitrify. It becomes difficult to obtain a uniform glass, and apatite crystals with large grain sizes precipitate, resulting in poor aesthetics.

The dental crystallized glass produced by the method of the present invention has a translucent milky white color, which approximates the appearance of natural teeth, but the color tone of natural teeth differs slightly from person to person. Therefore, by coloring the glass, it can be made to more closely resemble natural teeth. There are two methods for this coloring; one is to add Ce as a coloring agent to the glass raw material;
One method is to add components such as O□, MnO□, silver metal oxides, noble metal oxides, noble metal halides, and noble metal salts.The other method is to form crystallized glass and then apply an overcoat. be. In addition, the amount of colorant added is 10
It is preferable that it is 0.01 to 8% with respect to 0%. That is, if it is less than 0.01%, no effect as a coloring agent can be obtained, and if it is more than 8%, the coloring becomes too dark, which is not preferable.

Furthermore, in the present invention, in addition to the above-mentioned components, other components compatible with tetrasilicified fluoromylic crystals and other components compatible with calcium phosphate crystals, specifically, Group Ⅰ of the periodic table,
It is possible to add metal oxides of group (I) and oxides of silver metals.

However, in the present invention, the inclusion of Na2O is not preferred because it causes phase separation of the glass, making it difficult to obtain a uniform glass, and also increases the grain size of the fluoromica tetrasilicide crystals, resulting in poor aesthetics.

The method for producing the dental crystallized glass of the present invention will be specifically described below.

The amount of glass raw materials mentioned above was heated at 1350 to 1550°C for 2 to 30 minutes.
After being melted for 8 hours, it is poured into a mold and molded, and then this molded body is taken out from the mold and heat treated at 950 to 1150°C for about 2 to 8 hours. As the casting method, a centrifugal casting method, a vacuum casting method, etc. are used. That is, the centrifugal casting method is a method in which a mold is set in a spring-type or motor-type centrifugal casting machine, an appropriate amount of molten glass is poured into the mold, and centrifugal rotation is immediately started to cast glass in the mold. The vacuum casting method involves placing glass in a carbon or platinum crucible, melting the glass with a heater set around it, and then pouring the molten glass into a mold set in a casting machine.
In this method, the pressure is reduced using an air pump inside the casting machine, and once the pressure reduction is complete, the crucible is turned over and the glass is cast into the mold.

[Example] The present invention will be explained below based on examples.

The following table shows implementation FA (sample N) of the dental crystallized glass of the present invention.
[L 1-6 ) and a comparative example (sample N [L7.8)].

table (Mold opening%) Each glass sample in the table was prepared as follows.

Each glass raw material was put into a platinum crucible in the proportion shown in the table and melted at about 1450°C for about 4 hours in an electric furnace.Then, this molten glass was formed into a block shape and heated to about 1050-1075°C.
Heat treatment was performed for about 4 hours to produce crystallized glass. When the crystal phase of each sample was observed using powder X-ray method, sample t
In the crystallized glasses of Ja 1 to 6, both fluoromica tetrasilicide crystals and apatite crystals were precipitated, and in the crystallized glasses of sample N[L7, only fluoromica tetrasilicide crystals were precipitated, and in the crystallized glass of sample N[L8]. A plate of 8φ×1 m+s and a prism of 3×4×36+u+ were made6.
The biocompatibility shown in the table is determined by culturing skin fibroblasts from healthy individuals on the smooth and rough surfaces of crystallized glass processed into a starter plate at 37°C for 48 hours. The results are rated in two grades, excellent and good, and are shown in the table. The bending strength was measured using the well-known three-point load test method at a span of 30++us and a crosshead speed of 0.51111/min after scratching crystallized glass processed into a square cylinder with #600 abrasive paper. be.

Comparing the biocompatibility and bending strength of the products of the present invention (Samples N [L1 to 6) and conventional products (Samples No. 7 and 8), the products of the present invention have excellent biocompatibility and high bending strength. On the other hand, sample NIL7, which is a conventional product, has the same bending strength as the product of the present invention, but its biocompatibility is slightly inferior to that of the product of the present invention, and sample Y8 has excellent biocompatibility. However, its bending strength is extremely low.

In addition, each of the original molten glasses was cast as follows.

First, molten paraffin was poured into a prepared model, the paraffin was hardened, a wax model was created, a paraffin spool wire for guiding glass was welded to the wax model, and the model was embedded in an ethylsilicate investment material. After the investment material had hardened, the wax model and spool wire were incinerated by gradually increasing the temperature to 120-150°C, and then the mold was produced by gradually increasing the temperature and retaining at 700-800°C.

On the other hand, mold the molten glass into small blocks and
A glass melt remelted at 300 to 1500°C was poured onto the upper surface of the mold, and the mold was completed using a centrifugal casting machine.

The glass body produced in this way was removed from the mold and
Heat treatment was performed at 0 to 1100°C for about 4 hours. Visual observation of each sample revealed that all of them had good translucency equivalent to natural teeth, and in particular, No.
Samples No. 3 and N[L 6 exhibited color tones close to natural teeth and were excellent in aesthetics.

[Effects of the Invention] As described above, the dental crystallized glass produced by the method of the present invention has excellent aesthetics, particularly excellent biocompatibility, and high mechanical strength, and furthermore, it can be produced by a casting method. This makes it suitable for obtaining artificial teeth with high dimensional accuracy. It goes without saying that the dental crystallized glass of the present invention can also be used for cutting practice and viewing in the dental education process.

Patent applicant: Nippon Electric Glass Co., Ltd. Representative Kishi 1) Kiyoshi Saku

Claims (1)

[Claims] SiO_240.0-70.0% by weight percentage, MgO
3.0-7.8%, MgF_28.0-17.0%, A
l_2O_30-2.0%, K_2O4.0-20.0
%, ZrO_2+TiO_20.1-15.0%, Ca
O0.1-20.0%, P_2O_50.1-20.0
1. A method for producing dental crystallized glass, characterized in that glass raw materials in a range of 1.5% are melted, shaped, and heat treated to precipitate fluoromica tetrasilicide crystals and calcium phosphate crystals.