Method for molding dental restorations
First Claim
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.
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Accused Products
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.
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Citations
17 Claims
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1. A process for forming a ceramic dental restoration comprising the steps of;
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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. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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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.
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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)
- space="preserve" listing-type="tabular">______________________________________ Li.sub.2 O 8-12 Al.sub.2 O.sub.3 2-5.0 SiO.sub.2 75-85 Na.sub.2 O 0-2 K.sub.2 O 0-2 P.sub.2 O.sub.5 1.5-5 TiO.sub.2 0-2 ZrO 0-3 coloring oxides 0-5 ______________________________________
and the crucible is formed by the heat sintering of a particulate mixture of about 70 percent of fused silica and about 30 percent of a borosilicate glass having the following composition (by weight percent)
space="preserve" listing-type="tabular">______________________________________ SiO.sub.2 78 B.sub.2 O.sub.3 15 Al.sub.2 O.sub.3 2.5 Na.sub.2 O 4.5 ______________________________________and the glass-ceramic restoration is heat treating to affect crystal formation.
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8. The process of claim 1 wherein dental restoration is removed from the mold prior to heat treating.
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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)
- space="preserve" listing-type="tabular">______________________________________ Li.sub.2 O 8-12 Al.sub.2 O.sub.3 2-5.0 SiO.sub.2 75-85 Na.sub.2 O 0-2 K.sub.2 O 0-2 P.sub.2 O.sub.5 1.5-2.5 TiO.sub.2 0-2 ZrO 0-3 coloring oxides 0-5 ______________________________________
and the crucible is formed by the heat sintering of a particulate mixture of about 70 percent of fused silica and about 30 percent of a borosilicate glass having the following composition (by weight percent)
space="preserve" listing-type="tabular">______________________________________ SiO.sub.2 78 B.sub.2 O.sub.3 15 Al.sub.2 O.sub.3 2.5 Na.sub.2 O 4.5 ______________________________________and the glass-ceramic restoration is heat treating to affect crystal formation.
- space="preserve" listing-type="tabular">______________________________________ Li.sub.2 O 8-12 Al.sub.2 O.sub.3 2-5.0 SiO.sub.2 75-85 Na.sub.2 O 0-2 K.sub.2 O 0-2 P.sub.2 O.sub.5 1.5-5 TiO.sub.2 0-2 ZrO 0-3 coloring oxides 0-5 ______________________________________
space="preserve" listing-type="tabular">______________________________________ SiO.sub.2 78 B.sub.2 O.sub.3 15 Al.sub.2 O.sub.3 2.5 Na.sub.2 O 4.5 ______________________________________
- space="preserve" listing-type="tabular">______________________________________ Li.sub.2 O 8-12 Al.sub.2 O.sub.3 2-5.0 SiO.sub.2 75-85 Na.sub.2 O 0-2 K.sub.2 O 0-2 P.sub.2 O.sub.5 1.5-5 TiO.sub.2 0-2 ZrO 0-3 coloring oxides 0-5 ______________________________________
space="preserve" listing-type="tabular">______________________________________ SiO.sub.2 78 B.sub.2 O.sub.3 15 Al.sub.2 O.sub.3 2.5 Na.sub.2 O 4.5 ______________________________________
Specification