JP2001316131A - Glass ceramics and method for producing same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a glass ceramics containing leucite crystal which has a high thermal expansion and transparency matching with a metallic crown, and has the same fluorescent characteristic as a natural tooth. SOLUTION: This glass ceramics containing leucite crystal or powders of the same is a leucite matter glass ceramics containing 0.1 to 1.4 wt.% of CeO2 component and 0.1 to 2.5 wt.% of Tb4O7 component to provide the same fluorescent characteristic as a natural tooth.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to glass ceramics, their use and denture crowns. More specifically,
The present invention relates to glass ceramics with high thermal expansion, transparency and the same fluorescent properties as natural teeth, which are compatible with metallic crowns, their use and dentures.

[0002]

2. Description of the Related Art A technique for manufacturing a denture crown having the same appearance as natural teeth and excellent mechanical and chemical durability by embedding and welding porcelain powder on the surface of a metal crown. Is being developed. Noble metal alloys using gold, silver and palladium are used as metallic crown materials, but their thermal expansion coefficients are very large, 13.6 to 15.2 × 10 ⁻⁶ / ° C.
Range.

[0003] Therefore, the porcelain powder deposited and welded on the surface of the metal crown has a thermal expansion coefficient very similar to the high thermal expansion coefficient of the metal crown material, and has the same appearance as natural teeth. It is required to have transparency necessary for adding colors to reproduce the image.

Therefore, from the viewpoint of high thermal expansion and transparency, leucite crystals (4SiO ₂ , Al ₂ O ₃ , K ₂ O)
Is used as a porcelain material that is built up and welded to the surface of a metallic crown.

On the other hand, the appearance of natural teeth is diverse. Natural colors of the natural teeth are composed of enamel, dentin and teeth, as a matter of course, and the fluorescent color of each of the natural teeth is a complex fluorescent color. It is desired that a denture to be prosthetic can reproduce the same fluorescent color as a natural tooth under various lights such as sunlight, daylight, and fluorescent light.

[0006] To date, attempts have been made to add, for example, fluorescent pigment powders to dental porcelain or glass ceramics. For example, JP-A-8-40746 describes a technique of adding a yttrium silicate-based fluorescent pigment powder to glass ceramics. However, the technique described in Japanese Patent Application Laid-Open No. 8-40746 has the disadvantage that spots appear on the prepared denture crown depending on the particle size of the fluorescent pigment powder to be added. Also, JP-A-53-548
No. 93 describes a technique of adding fluorescent pigment powder obtained by adding europium as an activator to an alkaline earth salt of aluminosilicate to glass ceramics. However, the technique described in Japanese Patent Application Laid-Open No. 53-54893 has a problem that heat history due to heat treatment (500 ° C. or higher) such as welding appears as discoloration on the denture crown, and is not practical.

[0007] Dentures reproducing natural teeth are required to have various color changes in addition to fluorescent characteristics, and therefore have both fluorescent characteristics, transparency that can be colored, and high thermal expansion suitable for a metal crown. There has been a demand for the appearance of glass ceramics.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to provide a glass ceramic containing a leucite crystal having high thermal expansion and transparency suitable for a metallic crown.

[0009] It is an object of the present invention to provide a leucite crystal-containing glass ceramic which can reproduce the same fluorescent characteristics as natural teeth in a denture made by fusing and coating a vitreous material on a metal crown. .

It is an object of the present invention to provide a glass ceramic containing leucite crystals which does not change in fluorescence (color tone and strength) even when subjected to heat treatment such as welding and does not cause spots on denture crowns. And

An object of the present invention is to provide a denture crown obtained by laying and welding the above-mentioned leucite crystal-containing glass ceramic on the surface of a metal crown.

[0012]

The present inventor has solved the above-mentioned problems.
As a result of intensive research to achieve this, the present invention is finally completed.
Has come to fruition. 1. The present invention relates to CeO_Two0.1 to 1.4% by weight of the component
And Tb_FourO₇Component containing 0.1-2.5% by weight
Sight-like glass ceramic, which is the same firefly as natural teeth
Glass ceramic characterized by having optical properties
Or powder thereof. 2. The present invention relates to a method in which a glass ceramic or a powder thereof is
15 to 43% by weight, and 50 to 50%.
The coefficient of thermal expansion at 0 ° C. is 12 to 17.5 × 10 ^-6/ ℃
Even after heating at 850 ° C. for 3 hours, Na.
Glass-ceramics without K-feldspar crystal precipitation or its
The glass-ceramic or powder thereof according to 1 above, which is a powder.
It is a powder. 3. In the present invention, the glass ceramic is (1) SiO_Two
 53-65% by weight, Al_TwoO_Three 13 to 23% by weight, K
_TwoO 9-20% by weight, Na_TwoO 6-12% by weight, Li
_TwoO 0-2% by weight, MgO 0-3% by weight, CaO
0-3% by weight, B_TwoO_Three 0-3% by weight, BaO 0-3
Wt%, P_TwoO_Five 0-2% by weight, F 0-2% by weight, C
eO_Two 0.1-1.5% by weight and Tb_FourO₇ 0.1 ~
Glassy raw material powder containing 2.6% by weight and (2) SiO_Two
 53-64% by weight, Al_TwoO_Three 19-27% by weight, K
_TwoO 17-25% by weight, Rb_TwoO 0-5% by weight, Na
_TwoO0-2% by weight, Li_TwoO 0-2% by weight, MgO 0
Synthetic lusa containing 0.3 to 3% by weight and 0 to 3% by weight of CaO
After mixing with the crystal powder,
The gas described in the above item 2, which is obtained by heat treatment for one hour.
Las ceramics. 4. The present invention provides the glass ceramic described in the above item 1, 2 or 3.
Powder, emulsifiers, coloring pigments, phosphors, wetting agents and
A mixture of at least one additive selected from mixing agents.
Glass ceramic powder. 5. The present invention provides a dental prosthesis by embedding and welding coating on a metallic crown.
Described in 1, 2, 3 or 4 above for forming and decorating
The use of the glass ceramic powder described above. 6. The present invention provides the glass cell described in the above item 1, 2, 3, or 4.
Lamix powder is laid and welded on the surface of metal crown
It is a prosthetic crown.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The glass-ceramics containing leucite crystals or powders thereof according to the present invention are glass-ceramics containing leucite crystals or powders thereof having high thermal expansion properties and transparency suitable for metallic crowns. It is.

Further, the glass ceramic or powder thereof containing leucite crystal of the present invention reproduces the same fluorescent characteristics as natural teeth in a denture produced by welding and coating a vitreous material on a metallic crown. Glass ceramic or powder thereof.

The glass ceramic of the present invention contains
Leucite crystal is a leucite crystal of theoretical composition, S
iO_TwoLeucite solid solution in which
Is the crystal in which K in the -site crystal is partially substituted by Rb
At least one selected from the group consisting of: Unless otherwise specified below
If simply described as “leucite crystal”, SiO _Two
A leucite solid solution in which
Including crystals in which K in the crystal is partially substituted with Rb.
Shall be

The glass ceramic containing leucite crystals of the present invention or the powder thereof contains 0.1% of CeO ₂ component.
1.4 containing wt% and Tb ₄ O ₇ component 0.1 to 2.5 wt% as an essential requirement that is. 0.1 to 1.4% by weight of CeO ₂ component and 0.1 to 1.4% of Tb ₄ O ₇ component
The subject of the present invention can be solved only when the content is 2.5% by weight. When the content of the CeO ₂ component is more than 1.4% by weight, transparency is impaired due to emulsification or emulsification, and when the content of the CeO ₂ component is less than 0.1% by weight, the fluorescence intensity is compared with that of natural teeth. And become weaker. Also, T
When the content of the b ₄ O ₇ component is more than 2.5% by weight, the fluorescent color tone becomes different from that of the natural tooth, and when the content of the Tb ₄ O ₇ component is less than 0.1% by weight, the fluorescence intensity and Both colors are different from natural teeth.

The glass ceramic containing leucite crystals of the present invention or a powder thereof contains 0.1% of CeO ₂ component.
Preferably in contains 0.1 to 2 wt% to 1.2 wt%, and Tb ₄ O ₇ component, 0.2 to 0.2 wt%, and Tb ₄ O ₇ component CeO ₂ component It is particularly preferred to contain 1.5% by weight.

Such a glass ceramic containing leucite crystals of the present invention or a powder thereof is made of a glass ceramic containing leucite crystals or CeO in the powder thereof.
Easily manufactured by blending predetermined amounts of CeO ₂ component and Tb ₄ O ₇ component into glassy raw material when manufacturing glass ceramics so that the _two component content and the Tb ₄ O ₇ component fall within the above ranges. can do.

The leucite crystal-containing glass ceramic of the present invention or the powder thereof further includes (1) a leucite crystal content (saturated state) in which the amount of leucite crystal (saturated state) does not change during welding to a silver alloy crown. (2) No foreign crystals such as Na-K feldspar crystals are precipitated, that is, after the precipitation of leucite crystals reaches saturation, Leucite crystal-containing glass ceramics or powders that have a long time to start precipitation, or (3) Leucite crystal-containing glass ceramics or powders that do not cause a decrease in thermal expansion coefficient and emulsification of glass ceramics (4) Na after heating at 850 ° C. for 3 hours
It is desirable to have properties such as being a glass ceramic or a powder thereof which does not precipitate K-feldspar crystals (that is, is transparent and does not fluctuate in thermal expansion coefficient).

The glass ceramic having such properties or a powder thereof is produced, for example, by the following method.

That is, the above glass ceramic is obtained by mixing a vitreous raw material and a synthetic leucite crystal (seed crystal),
It is manufactured by heat treatment.

The vitreous raw material is, for example, SiO ₂
65 wt%, Al ₂ O ₃ 13~23 wt%, K ₂ O 9
20 wt%, Na ₂ O 6~12 wt%, CeO ₂
0.1 to 1.5 wt%, and Tb ₄ O ₇ 0.1 to 2.6 wt% good glassy material comprising as essential components, Li ₂ O as another arbitrary component of the components, MgO, CaO, B ₂
O ₃ , BaO, P ₂ O ₅ , F and the like may be contained. For example, Li ₂ O is 2% by weight or less, MgO is 3% by weight or less,
CaO is 3% by weight or less, B ₂ O ₃ is 3% by weight or less, BaO
Is 3% by weight or less, P ₂ O ₅ is 2% by weight or less, F is 2% by weight
It should be: Further, the total content of optional components in the vitreous material is usually preferably 6% by weight or less. CeO ₂
Has the effect of promoting vitrification of the raw material powder and fining of the glass.

The vitreous raw material is prepared by a usual melting method. For example, appropriate starting materials such as oxides, hydroxides, and carbonates are mixed at a desired weight ratio, and 1550 to 1
Melts at 650 ° C for 2-5 hours. As the crucible, an ordinary crucible made of high alumina, platinum or the like is used, and a crucible made of high Rh-containing platinum or Zr-containing platinum is particularly preferable.

The vitreous raw material is preferably a pulverized product. For the pulverization, for example, the molten glass prepared above is poured into water and pulverized, dried, and then dried by a crusher such as a roll mill, a ball mill, or a jet mill.
(μm or less = 200 mesh or less).

The synthetic leucite crystal is, for example, SiO ₂
53-64 wt%, Al ₂ O ₃ 19~27 wt% and K ₂ O 17 to 25 wt% synthetic leucite crystals often comprising as essential components, Rb ₂ O as in addition to optional components of the above components, Na ₂ O, Li ₂ O, MgO, CaO and the like may be contained. For example Rb ₂ O 0 to 5 wt% or less,
Na ₂ O is 2% by weight or less, Li ₂ O is 2% by weight or less, Mg
O is preferably 3% by weight or less and CaO is preferably 3% by weight or less. In addition, the total content of optional components in the synthetic leucite crystal is usually preferably 5% by weight or less.

The synthetic leucite crystal is also prepared by a usual melting method, similarly to the preparation of the vitreous material. For example, appropriate starting materials such as oxides, hydroxides, and carbonates are mixed in a desired weight ratio, melted at a temperature of 1700 ° C. or more for 2 hours or more, and then gradually cooled to 1200 ° C. to complete crystallization. After cooling, cool to room temperature. The completion of crystallization is confirmed by the powder X-ray diffraction analysis. At the time of the slow cooling, it is preferable to maintain the temperature at an intermediate temperature of the slow cooling, for example, 1300 to 1400 ° C. for 1 to 2 hours. As the crucible, it is preferable to use a high alumina crucible from the crystal taking-out step. In addition, the synthetic leucite crystal was placed in a crucible containing the same mixture of starting materials as described above,
It can also be synthesized by a solid reaction fired at a temperature of 0 ° C. or more for a long time. In this case, the higher the firing temperature, the shorter the synthesis time. For example, at 1500 ° C., the solid-state reaction is almost completed in about 5 hours.

The synthetic leucite crystals are preferably ground. For the pulverization, for example, the high-temperature synthetic leucite crystal prepared above is put into water together with a crucible, quenched and crushed, a crystal part is collected, dried, and then subjected to a desired particle size (75 μm) by a crusher such as a roll mill or a ball mill. It is better to pulverize to the following).

The particle size of the pulverized synthetic leucite crystal used as a seed crystal in the present invention is not particularly limited. The average particle size of the crushed synthetic leucite crystal is 75
The object of the present invention is achieved as long as it is not more than μm. For example, the object of the present invention can be achieved even if the average particle size of the pulverized synthetic leucite crystal is about 3.5 μm.

The glass ceramic of the present invention is obtained by mixing the vitreous raw material prepared above with a synthetic leucite crystal (seed crystal), for example, at a temperature of usually 800 to 900 ° C., usually at a temperature of 1 to 900 ° C.
It is manufactured by performing crystallization heat treatment for up to 3 hours.

The mixing ratio of the vitreous raw material and the synthetic leucite crystal is usually 0.5 to 5 with respect to the former.
% By weight, preferably 1 to 2% by weight. If the mixing ratio of the vitreous raw material and the synthetic leucite crystal is out of the above range, the object of the present invention may not be achieved in some cases.

For example, when only the vitreous raw material is heat-treated without using the synthetic leucite crystal, the following results are obtained. That is, even when only the vitreous raw material is heat-treated, leucite crystals are generated and multiplied. This is presumably because the edge of the pulverized vitreous material plays the role of a crystal nucleus. In the case of relying on such spontaneous crystal nuclei, the time required for the leucite crystal to proliferate and reach saturation in the glass phase is prolonged, and the stable phase is reached before reaching saturation. Na · K feldspar crystals are eutectoid, and as a result, fluctuations in the coefficient of thermal expansion and emulsification cannot be avoided.

Further, when the mixing ratio of the synthetic leucite crystal is large, it is difficult to remove bubbles when producing a fired body from glass ceramics, and furthermore, it is not practical because fine cracks are generated in the fired body.

Thus, the glass-ceramics of the present invention in which fine leucite crystals are precipitated in the glass phase in a saturated or nearly saturated state and the crystals are dispersed as a metastable crystal phase is produced. You.

The leucite crystal-containing glass ceramic of the present invention produced by the above method has an average particle size of 20 μm.
It is a glass ceramic containing the following leucite crystals. This glass ceramic has an average particle size of 20
Leucite crystals of μm or less are precipitated in the glass matrix in a state of saturation or near saturation, and the crystals are in a state of being dispersed as a metastable crystal phase.

The amount of leucite crystals contained in the glass ceramic of the present invention produced by the above method is usually 15 to 43% by weight. The coefficient of thermal expansion of the glass ceramic of the present invention at 25 to 500 ° C. varies depending on the amount of leucite crystals contained in the glass ceramic, and cannot be unconditionally determined.
7.5 × 10 ⁻⁶ / ° C.

The glass-ceramic of the present invention produced by the above-mentioned method does not change the amount of leucite crystals (saturated state) during the welding operation to the metallic crown,
No foreign crystals such as K-feldspar crystals are precipitated, and after the precipitation of leucite crystals reaches saturation, it takes a long time until the precipitation of foreign crystals such as Na-K feldspar crystals starts. This glass ceramic does not cause a decrease in the coefficient of thermal expansion of the glass ceramic and no emulsification during the welding operation to the metallic crown.

When the glass ceramics of the present invention is used, for example, for dental use, the glass ceramics are once formed into a powder form, and then formed into a compact or sintered body.

In crushing the glass ceramic of the present invention into a powder form, for example, a high-temperature substance immediately after the above-mentioned crystallization heat treatment is poured into water, quenched and crushed, dried, and further crushed by a crusher such as a roll mill or a ball mill. It is preferable to pulverize to a desired particle size (75 μm or less) and mix a classified product.

At least one additive selected from emulsifiers, coloring pigments, phosphors, wetting agents and kneading agents can be added to the glass ceramic powder of the present invention.

As the emulsifier, coloring pigment, phosphor, wetting agent and kneading agent, conventionally known ones can be widely used. The amounts of these additives are not particularly limited as long as they do not impair the effects of the present invention.

In using the glass-ceramic powder of the present invention for dental use, the same usage method as that of a conventional porcelain can be adopted. For example, the above-mentioned powder can be laid and welded on a metal crown, and further, colored firing, shape modification and firing can be repeated to obtain a denture crown having excellent aesthetics. In the glass ceramics of the present invention, these series of steps, for example, firing (specified in JIS T 6516 (the firing conditions are specified by the manufacturer); placed in a furnace at 600 ° C., and subjected to vacuum (about 30 mm / Hg) 60 ℃
/ Min, and held for 1 minute, then taken out into the atmosphere and allowed to cool) for about 10 times (total firing time = about 1 hour), while the amount of leucite crystals in the glass ceramic did not change. Accordingly, a glass ceramic sintered body having a constant coefficient of thermal expansion and excellent transparency is obtained.

As the metal crown, a crown made of a noble metal alloy is preferable. Examples of the noble metal alloy include gold high carat, gold middle carat, gold silver palladium alloy, gold palladium alloy, palladium silver alloy, palladium alloy and the like.

In building and welding the above powder on a metal crown, a glass ceramic powder added with an emulsifier is used in the undercoating to conceal the metal color, and in order to imitate natural teeth. It is desirable to use a glass ceramic powder to which a coloring pigment is added for the upper layer coating.

An example of a desirable method for producing an artificial denture crown is as follows. First, opaque powder is kneaded using a water-soluble kneading solution, coated and dried on a metal crown, and then baked under vacuum ( 9
00 ° C). Next, dentin corresponding to the dentin of the natural tooth is kneaded and coated in the same manner, and the coating layer is shaved in a semi-dry state, shaping, drying and firing, and the enamel is also subjected to the same process to achieve harmony with the desired natural tooth. An artificial denture with an arbitrary shape and color can be produced by applying a denture shape having the appearance as described above, further applying a thin glaze, drying and firing.

[0045]

The glass ceramic or powder thereof containing leucite crystals of the present invention has a high thermal expansion property and transparency suitable for a metallic crown.

Further, the glass ceramic or powder thereof containing leucite crystals of the present invention reproduces the same fluorescent characteristics as natural teeth in dentures produced by fusing and coating a vitreous material on a metallic crown. it can. That is, the glass ceramic of the present invention or the powder thereof has the same fluorescence characteristics as natural teeth, and emits the same fluorescence as natural teeth when the glass ceramic of the present invention is irradiated with near ultraviolet rays.

The glass ceramic of the present invention is made of CeO ₂
Component (blue-white fluorescence) and Tb ₄ O ₇ component (green fluorescence) at the same time, and by appropriately selecting the amount and ratio of the two components, the composition is adjusted to emit the same fluorescence as natural teeth. And can be adjusted to emit various combined fluorescent colors.

The heat history of the glass ceramic of the present invention, even when subjected to heat treatment such as welding, does not discolor the heat history and does not appear on the denture crown, and no spots appear on the denture crown.

The glass ceramic of the present invention is excellent in optical transparency, but further contains 50% by weight or more of a glass phase. Therefore, because of excellent sinterability, defoaming easily occurs by vacuum sintering, and further, a material having excellent wettability with a metal surface and high welding strength can be obtained. Moreover, the pulverized and sized product of the glass ceramic of the present invention surprisingly shows softening fluidity by heating even when a large amount of an emulsifier, a colored inorganic pigment, a phosphor or the like is added. This is basically due to the fact that it contains a large amount of a glass phase. By utilizing this feature, the color tone of the metallic crown is concealed (opaque) and the color tone of the natural tooth is reproduced (dentin-dentin, enamel-enamel, It is possible to adjust the addition amount of the colored pigment powder in a wide range so that the gloss-glaze can be predominantly developed.

[0050]

The present invention will be further clarified with reference to the following examples.

First, the basic composition of the vitreous raw material and the composition of the leucite crystal (seed crystal) used in the following Examples and Comparative Examples are shown below.

Basic composition of crow material No. 1: SiO ₂
63.7 wt%, Al ₂ O ₃ 15.0 wt%, K ₂ O
10.7% by weight, 8.5% by weight of Na ₂ O, MgO
0.3% by weight, CaO 1.2% by weight, B ₂ O ₃ 0.6
weight%.

Basic composition of crow material No. 2: SiO ₂
62.1% by weight, Al ₂ O ₃ 15.0% by weight, K ₂ O
11.8% by weight, 9.0% by weight of Na ₂ O, MgO
0.3% by weight, CaO 1.2% by weight, B ₂ O ₃ 0.6
weight%.

Composition of leucite crystal (seed crystal): Si
55.1% by weight of O _2, 23.3% by weight of Al ₂ O ₃ , K ₂ O
21.6% by weight.

Examples 1 to 5 The vitreous raw material was prepared according to the above basic composition No. 1 or No. 2
Is a composition in which a part of SiO ₂ is replaced by a CeO ₂ component and a Tb ₄ O ₇ component. Table 1 shows the substitution amounts of the CeO ₂ component and the Tb ₄ O ₇ component.

100 parts by weight of powdery vitreous raw material (particle size = 75 μm or less) and 1 part by weight of powdery leucite crystal (seed crystal) (particle size = 75 μm or less) were mixed at 850 ° C.
, And then cooled to produce the glass ceramic of the present invention.

COMPARATIVE EXAMPLE 1 Except not containing the CeO ₂ component and the Tb ₄ O ₇ component,
A glass ceramic was manufactured in the same manner as in Example 1.

Comparative Example 2 The above basic composition No. A glass ceramic was produced in the same manner as in Example 1, except that 0.05% by weight of the SiO ₂ component 1 was replaced with a CeO ₂ component and 3% by weight was replaced with a Tb ₄ O ₇ component.

Comparative Example 3 The above basic composition No. A glass ceramic was produced in the same manner as in Example 1 except that 1.5% by weight of the SiO ₂ component 1 was replaced with a CeO ₂ component and 0.05% by weight was replaced with a Tb ₄ O ₇ component.

Comparative Example 4 The above basic composition No. A glass ceramic was produced in the same manner as in Example 1 except that 1.5% by weight of the SiO ₂ component of Example 1 was replaced by a CeO ₂ component, and 0.5% by weight was replaced by a Tb ₄ O ₇ component.

Each of the glass ceramics obtained in the above Examples and Comparative Examples was pulverized to a particle size of 75 μm or less, and the powder was put in a mold and formed by a biaxial press. Vacuum firing is JIS T
The measurement was performed based on the 6516 regulation. That is, after the compact obtained above was placed in a furnace at 600 ° C. to make a vacuum,
After heating to 900 ° C. for 1 minute and heating and sintering at 900 ° C. for 1 minute, it was taken out into the atmosphere and allowed to cool. This vacuum firing was performed once, and the air firing was performed once, to obtain a twice fired sample. A sample fired three times and fired once in the atmosphere was used as a fired sample four times.

Further, the coefficient of thermal expansion (α: × 10 ⁻⁶ / ° C., average value between 50 and 500 ° C.) was measured by the method specified in JIS T 6516. α ₂ is the thermal expansion coefficient of the twice fired sample, and α ₄ is the thermal expansion coefficient of the four fired sample.

The evaluation of the fluorescence intensity was performed by irradiating ultraviolet rays of 365 nm and comparing with the crown portion of the natural tooth, and evaluated visually. Evaluation criteria for fluorescence intensity; A: comparable to natural teeth; B: stronger than natural teeth; C: different in color tone from natural teeth.

[0064]

[Table 1]

Examples 1 to 5 were all transparent and had the same level of fluorescence characteristics as natural teeth.

Even after each of the ceramics obtained in Examples 1 to 5 was repeatedly fired four times, different crystals such as Na-K feldspar crystals did not precipitate, and the coefficient of thermal expansion did not decrease. Emulsification did not occur.

Comparative Example 1, as a matter of course, did not show fluorescence.

In Comparative Example 2, the amount of CeO ₂ component was small (0.
05% by weight), the fluorescence intensity was weak, the green color was strong, and the fluorescence color was far from natural teeth.

Comparative Examples 3 and 4 are examples in which the CeO ₂ component is added in a large amount. However, since opalescence or emulsification occurs, the possibility of opaque material remains, but it cannot be used from the viewpoint of transparency. Was.

Even after the ceramics obtained in Examples 1 to 5 were repeatedly fired four times, no heterogeneous crystals such as Na-K feldspar crystals were precipitated, the coefficient of thermal expansion was not reduced, and the emulsion was not emulsified. No change occurred.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Takeshi Hoshikawa 1090-3 Oya, Kagami-cho, Kagami-cho, Kami-gun, Kochi Pref. 3-7, Sanadayamacho, Ward Yamamoto Kikinzoku Metal Co., Ltd. (72) Inventor Teruo Anraku 3-7 Sanadayamacho, Tennoji-ku, Osaka-shi, Osaka F-term (reference) 4G062 AA08 AA09 AA11 AA15 BB01 BB06 CC01 CC09 DA06 DB04 DC01 DC02 DC03 DD01 DD02 DD03 DE01 DF01 EA01 EA02 EA03 EB01 EB02 EB03 EB04 EC03 EC04 ED01 ED02 ED03 EE01 GB EE01 EE03 EF01 EG01 FG01 F01 FF01 GC01 GD01 GE01 GE02 GE03 HH01 HH02 HH03 HH05 HH07 HH09 HH11 HH13 HH15 HH17 HH20 JJ01 JJ03 JJ05 JJ07 JJ10 KK01 KK02 KK03 KK05 KK07 KK10 M M20 NN29 NN33 NN34 PP01 PP13 PP14 QQ14

Claims (6)

[Claims] 1. A leucite glass ceramic containing 0.1 to 1.4% by weight of a CeO ₂ component and 0.1 to 2.5% by weight of a Tb ₄ O ₇ component, and has the same fluorescence as natural teeth. A glass ceramic or a powder thereof having characteristics. 2. The glass ceramic or its powder contains 15 to 43% by weight of leucite crystals, and 50 to 50% by weight.
The coefficient of thermal expansion at 0 ° C. is 12 to 17.5 × 10 ⁻⁶ / ° C.
Even after heating at 850 ° C. for 3 hours, Na.
The glass-ceramic or powder thereof according to claim 1, which is a glass-ceramic or powder thereof without precipitation of K-feldspar crystals. 3. The method according to claim 1, wherein the glass ceramic is (1) SiO_Two
 53-65% by weight, Al_TwoO_Three 13 to 23% by weight, K
_TwoO 9-20% by weight, Na_TwoO 6-12% by weight, Li
_TwoO 0-2% by weight, MgO 0-3% by weight, CaO
0-3% by weight, B_TwoO_Three 0-3% by weight, BaO 0-3
Wt%, P_TwoO_Five 0-2% by weight, F0-2% by weight, Ce
O_Two 0.1-1.5% by weight and Tb_FourO₇ 0.1 ~
Glassy raw material powder containing 2.6% by weight and (2) SiO_Two
 53-64% by weight, Al_TwoO_Three19-27% by weight, K_Two
O 17-25% by weight, Rb_TwoO 0-5% by weight, Na _Two
O 0-2% by weight, Li_TwoO 0-2% by weight, MgO
Synthetic lew containing 0 to 3% by weight and 0 to 3% by weight of CaO
After mixing with the site crystal powder, 5 to 750-950 ° C.
3. The composition according to claim 2, which is obtained by heat treatment for 1 to 1 hour.
Glass ceramics. 4. The glass ceramic powder according to claim 1, 2 or 3, wherein at least one additive selected from an emulsifier, a coloring pigment, a phosphor, a wetting agent and a kneading agent. Is mixed with glass ceramic powder. 5. The glass-ceramic powder according to claim 1, which is used for forming and decorating a denture by building up and fusing the metal crown. Use of. 6. A denture crown obtained by building and welding the glass ceramic powder according to claim 1, 2, 3, or 4 on the surface of a metal crown.