Method for molding dental restorations

• US 5,507,981 A
• Filed: 05/31/1994
• Issued: 04/16/1996
• Est. Priority Date: 05/31/1994
• Status: Expired due to Fees

• Current Assignee: TEC Ventures, Inc.
• Original Assignee: TEL Ventures Incorporated
• Inventors: Petticrew, Richard W.
• Primary Examiner(s): Fiorilla, Christopher A.
• Application Number:
  US08/250,926
• Time in Patent Office: 686 Days
• Field of Search: 264/16, 264/17, 264/19, 264/234, 264/328.2, 264/328.4, 264/313, 65/21.5, 65/66
• US Class Current: 264/16
• CPC Class Codes: A61C 13/20 Methods or devices for soldering, casting, moulding or melting A61C13/04, A61C13/081 take precedence
• CPC Class Codes: B28B 1/24 by injection moulding injection moulding of ceramic slips B28B1/265; of tubular articles B28B21/38
• CPC Class Codes: B28B 5/04 in moulds moved in succession past one or more shaping stations on turn-tables B28B5/06
• CPC Class Codes: C03C 10/00 Devitrified glass ceramics, i.e. glass ceramics having a crystalline phase dispersed in a glassy phase and constituting at least 50% by weight of the total composition
• CPC Class Codes: C03C 3/097 containing phosphorus, niobium or tantalum
• CPC Class Codes: C03C 4/0021 for dental use
• CPC Class Codes: Y10T 428/13 Hollow or container type article [e.g., tube, vase, etc.]

Abstract

A process for the formation of dental restorations from glass-ceramic materials and the resulting dental restorations. In this invention, a dental restoration is prepared by placing a glass-ceramic material in a heat-pressure deformable crucible. Heat is then applied to the crucible in order to bring the glass-ceramic material to a working range at temperatures above its liquidus temperature. The crucible in which the glass-ceramic material is placed has heat-pressure deformation properties which are matched to the working temperature of the glass-ceramic material being heated. The heat deformation properties of the crucible must be such that when the glass-ceramic material in the crucible is in the working range the crucible is heat-pressure deformable without rupturing. Once the glass-ceramic material is heated to its working temperature, the crucible is brought into contact with a mold having a preformed cavity therein, the cavity being in the shape of the desired dental restoration. As the distance between the heated glass-ceramic material and the mold is decreased, the crucible is deformed to form a seal with the mold thereby facilitating the injection of the molten glass-ceramic material into the mold cavity. An interactive seal between the crucible and the mold may be provided for. The composite process may be carried out in a vacuum. The resulting dental restoration has superior optical esthetic and strength properties. The invention further includes the heat-pressure deformable crucible which is useful in the process of this invention and the related apparatus.

Claims

1. A process for forming a ceramic dental restoration comprising the steps of;

a. placing a glass-ceramic material in a heat-pressure deformable crucible;

b. heating the crucible and glass-ceramic material to a temperature at which said crucible becomes heat-pressure deformable and the glass-ceramic material is moldable;

c. bringing the heated crucible into contact with a mold having a sprue end and a preformed cavity therein;

d. continuing to move the crucible into contact with the mold thereby causing the crucible to deform against the mold, causing a seal to form therebetween and causing the moldable glass-ceramic material to be injected into said cavity, thereby forming a dental restoration;

e. cooling the mold and the glass ceramic dental restoration therein;

f. removing the formed glass ceramic restoration from the mold;

g. heat treating the dental restoration;

h. finishing the dental restoration.

2. The process of claim 1 wherein the crucible containing the glass-ceramic material therein and the mold are axially disposed in relation to each other.

3. The process of claim 2 wherein the glass-ceramic material is heated to a temperature above its liquidus temperature, to a working range where its viscosity is about log 3 to about 4 P and the crucible is heat pressure deformable and has a viscosity of about log 5 to about 7 P at the working range of the glass-ceramic material.

4. The process of claim 2 wherein the glass-ceramic material has the following composition (by weight percent)

5. The process of claim 1 wherein the crucible containing the glass-ceramic material therein and the mold are vertically disposed in relation to each other.

6. The process of claim 5 wherein the glass-ceramic material is heated to a temperature above its liquidus temperature, to a working range where its viscosity is about log 3 to about 4 P and the crucible is heat pressure deformable and has a viscosity of about log 5 to about 7 P at the working range of the glass-ceramic material.

7. The process of claim 5 wherein the glass-ceramic material has the following composition (by weight percent)

8. The process of claim 1 wherein dental restoration is removed from the mold prior to heat treating.

9. The process of claim 8 wherein the glass-ceramic material is heated to a temperature above its liquidus temperature,to a working range where its viscosity is about log 3 to about 4 P and the crucible is heat pressure deformable and has a viscosity of about log 5 to about 7 P at the working range of the glass-ceramic material.

10. The process of claim 8 wherein the glass-ceramic material has the following composition (by weight percent)

11. The process of claim 1 wherein the dental restoration is removed from the mold and reinvested prior to heat treating.

12. The process of claim 11 wherein the glass-ceramic material is heated to a temperature above its liquidus temperature, to a working range where its viscosity is about log 3 to about 4 P and the crucible is heat pressure deformable and has a viscosity of about log 5 to about 7 P at the working range of the glass-ceramic material.

13. The process of claim 11 wherein the glass-ceramic material has the following composition (by weight percent)

14. The process of claim 1 wherein the glass-ceramic material is heated to a temperature above its liquidus temperature, to a working range where its viscosity is about log 3 to about 4 P and the crucible is heat pressure deformable and has a viscosity of about log 5 to about 7 P at the working range of the glass-ceramic material.

15. The process of claim 1 wherein the glass-ceramic material has the following composition (by weight percent)

16. The process of claim 1 wherein the sprue end of the mold incorporates a circular cavity which interacts with the crucible when the deformable crucible is brought into contact with the mold.

17. The process of claim 1 wherein the sprue end of the mold incorporates a circular cavity the axis of which is parallel with the axis of the mold, the outer edges of said cavity having a plurality of annular grooves, which grooves interact with the crucible when the deformable crucible is brought into contact with the mold.