Method of preparing a ceramic artificial crown and a preparation kit used therefor

• US 20030215770A1
• Filed: 05/12/2003
• Published: 11/20/2003
• Est. Priority Date: 09/20/1999
• Status: Active Grant

• Current Assignee: Kyoichi Fujinami, Masaaki Ushioda, Masato Sekino, Osamu Iwamoto
• Original Assignee: Kyoichi Fujinami, Masaaki Ushioda, Masato Sekino, Osamu Iwamoto
• Inventors: Iwamoto, Osamu, Fujinami, Kyoichi, Sekino, Masato, Ushioda, Masaaki
• Granted Patent: US 6,923,420 B2
• Time in Patent Office: Days
• US Class Current: 433/218
• CPC Class Codes: A61C 13/083 Porcelain or ceramic teeth A61C13/081 takes precedence; preparations A61K6/80
• CPC Class Codes: A61C 13/09 Composite teeth, e.g. front and back section A61C13/0835, A61C13/1023 take precedence; Multilayer teeth
• CPC Class Codes: A61C 13/20 Methods or devices for soldering, casting, moulding or melting A61C13/04, A61C13/081 take precedence
• CPC Class Codes: A61C 5/77 Methods or devices for making crowns
• CPC Class Codes: A61K 6/17 Particle size
• CPC Class Codes: A61K 6/78 Pigments
• CPC Class Codes: A61K 6/807 comprising magnesium oxide
• CPC Class Codes: A61K 6/824 comprising transition metal oxides
• CPC Class Codes: A61K 6/887 Compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
• CPC Class Codes: A61K 6/891 Compounds obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds
• CPC Class Codes: C03C 4/0021 for dental use
• CPC Class Codes: C03C 8/14 Glass frit mixtures having non-frit additions, e.g. opacifiers, colorants, mill-additions

Abstract

A method of preparing a ceramic artificial crown by applying at least one kind of dental porcelain selected from the group consisting of a body porcelain, an incisal porcelain and a translucent porcelain onto the surface of a ceramic core molded by heating and softening a ceramic material and putting it into a mold with the application of a pressure followed by firing; wherein

said mold is the one formed by burning a wax pattern after having removed a crucible former from an assembly which comprises:

said crucible former having a pole member formed on the central portion of a cylinder with bottom, said pole member having a recessed fitting portion at a central portion in the upper surface thereof;

said wax pattern secured to said recessed fitting portion and applied with a solid lubricant on the surface thereof;

a ring with a backing layer that engages with said cylinder with bottom; and

a investment material filled and cured between said ring and a tooth model; and wherein

a portion corresponding to the pole member of the crucible former of said mold is filled with a ceramic material which is, then, pushed by a plunger to mold a ceramic core.

This method makes it possible to efficiently prepare a fully ceramic artificial crown of a high quality in a short period of time.

Claims

1. A method of preparing a ceramic artificial crown by applying at least one kind of dental porcelain selected from the group consisting of a body porcelain, an incisal porcelain and a translucent porcelain onto the surface of a ceramic core molded by heating and softening a ceramic material and putting it into a mold with the application of a pressure followed by firing;

wherein

said mold is formed by burning a wax pattern after having removed a crucible former from an assembly which comprises;

said crucible former having a pole member formed on the central portion of a cylinder with bottom, said pole member having a recessed fitting portion at a central portion in the upper surface thereof;

said wax pattern secured to said recessed fitting portion and applied with a solid lubricant on the surface thereof;

a ring with a backing layer that engages with said cylinder with bottom; and

a investment material filled and cured between said ring and a tooth-shaped model; and

wherein

a portion corresponding to the pole member of the crucible former of said mold is filled with a ceramic material which is, then, pushed by a plunger to mold a ceramic core.

2. A preparation method according to claim 1, further including a step of coloring the surface by applying a surface-coloring material onto the surface of a fired article on which a porcelain is baked followed by firing, and a step of lustering by applying a glazing powder onto the surface of the fired article obtained through the above step followed by firing, thereby to obtain a highly aesthetic fully ceramic artificial crown.

3. A preparation method according to claim 1 or 2, wherein the solid lubricant is applied to the wax pattern by applying a suspension containing a solid lubricant, an organic binder and an organic solvent, followed by drying.

4. A preparation method according to claim 3, wherein said suspension comprises from 0.1 to 30% by weight of a solid lubricant, from 0.1 to 20% by weight of an organic binder and the remainder of an organic solvent.

5. A preparation method according to any one of claims 1 to 4, wherein the ceramic material put into the mold has a viscosity of from 10² to 10⁹ poises.

6. A preparation method according to any one of claims 1 to 5, wherein the ceramic material is a crystallizable MgO—

CaO—

SiO₂ glass material.

7. A preparation method according to any one of claims 1 to 6, wherein the pole member of the crucible former has a diameter which is widened downward being tapered at 0.005 to 0.120.

8. A preparation method according to any one of claims 1 to 7, wherein said plunger is made of a ceramic material having a melting point or a decomposition temperature, whichever is lower, which is higher than a temperature of forming the ceramic artificial crown and having a thermal conductivity of not smaller than 0.1 (cal·

cm<sup>−

1</sup>·

sec<sup>−

1</sup>·

°

C.<sup>−

1</sup>) or a coefficient of linear expansion of not larger than 4.0×

10<sup>−

6</sup> (°

C.<sup>−

1</sup>).

9. A preparation method according to any one of claims 1 to 8, wherein a solid lubricant is adhered in advance onto the surface of the plunger that comes into contact with the ceramic material.

10. A preparation method according to any one of claims 1 to 9, wherein a dental porcelain is baked after having applied, onto the surface of a ceramic core, a kneaded product obtained by kneading, with water, a body porcelain, an incisal porcelain or a translucent porcelain which comprises:

100 parts by weight of a glass material containing, on the basis of the oxides, 57 to 65% by weight of SiO₂, 8 to 18% by weight of Al₂O₃, 15 to 25% by weight of B₂O₃, 0.1 to 2% by weight of ZnO, 3 to 7% by weight of Na₂O and 2 to 8% by weight of Li₂O; and

0.1 to 10 parts by weight of an inorganic crystalline powder having a refractive index which is different from the refractive index of the glass material by 0.01 to 0.1, and having an average particle diameter of from 0.1 to 10 μ

m.

11. A preparation method according to any one of claims 1 to 10, wherein the step of coloring the surface and the step of lustering are effected by applying a kneaded product onto the surface of the fired article obtained in the step preceding said steps followed by firing, said kneaded product being obtained by kneading a staining powder and a glazing powder each comprising, as a chief sintering component, a glass material containing, on the basis of the oxides, 57 to 65% by weight of SiO₂, 8 to 18% by weight of Al₂O₃, 15 to 25% by weight of B₂O₃, 0.1 to 2% by weight of ZnO, 3 to 7% by weight of Na₂O and 2 to 8% by weight of Li₂O with a kneading solution containing not less than 5% by weight of an ester compound having a boiling point of from 100 to 250°

C.

12. A dental porcelain used as a body porcelain, an incisal porcelain or a translucent porcelain in the preparation of a ceramic artificial crown, and comprising:

100 parts by weight of a glass material containing, on the basis of the oxides, 57 to 65% by weight of SiO₂, 8 to 18% by weight of Al₂O₃, 15 to 25% by weight of B₂O₃, 0.1 to 2% by weight of ZnO, 3 to 7% by weight of Na₂O and 2 to 8% by weight of Li₂O; and

0.1 to 10 parts by weight of an inorganic crystalline powder having a refractive index which is different from the refractive index of the glass material by 0.01 to 0.1, and having an average particle diameter of from 0.1 to 10 μ

m.

13. A dental porcelain according to claim 12, wherein said glass material has a coefficient of linear expansion of not larger than 6.0×

10<sup>−

6</sup> (°

C.<sup>−

1</sup>).

14. A kit used for the preparation of a ceramic artificial crown, which comprises:

a crucible former having a pole member formed on the central portion of a cylinder with bottom, said pole member having a recessed fitting portion at a central portion in the upper surface thereof with which a wax pattern is to be secured;

a ring that engages with the cylinder with bottom of said crucible former;

a backing member fitted to the inner surface of the ring;

a investment material filled between the crucible former and the ring;

a plunger for pushing the ceramic member filled in a portion corresponding to the pole member of the crucible former of the mold that is formed by curing the investment material, removing the crucible former and burning the wax pattern; and

a container for suspension to apply a solid lubricant onto the wax pattern or onto a portion of the plunger that comes into contact with the ceramics.

15. A kit used for the preparation of a ceramic artificial crown while imparting color and luster, comprising:

a staining powder and a glazing powder each containing, as a sintering component and on the basis of the oxides, 57 to 65% by weight of SiO₂, 8 to 18% by weight of Al₂O₃, 15 to 25% by weight of B₂O₃, 0.1 to 2% by weight of ZnO, 3 to 7% by weight of Na₂O and 2 to 8% by weight of Li₂O; and

a container for a kneading solution that contains not less than 5% by weight of an ester compound having a boiling point of from 100 to 250°

C.