Glass-ceramic and artificial dental crown formed therefrom

• US 5,246,889 A
• Filed: 02/26/1992
• Issued: 09/21/1993
• Est. Priority Date: 03/07/1991
• Status: Expired due to Fees

• Current Assignee: Hoya Corporation
• Original Assignee: Hoya Corporation
• Inventors: Kasuga, Toshihiro, Kasuga, Tomoko
• Primary Examiner(s): GROUP, KARL E
• Application Number:
  US07/841,190
• Time in Patent Office: 573 Days
• Field of Search: 501/5, 501/3, 501/69, 501/70, 106/35
• US Class Current: 501/3
• CPC Class Codes: A61K 6/807 comprising magnesium oxide
• CPC Class Codes: A61K 6/816 comprising titanium oxide
• CPC Class Codes: A61K 6/818 comprising zirconium oxide
• CPC Class Codes: A61K 6/824 comprising transition metal oxides
• CPC Class Codes: A61K 6/833 Glass-ceramic composites
• CPC Class Codes: C03C 10/0045 containing SiO2, Al2O3 and MgO as main constituents
• CPC Class Codes: C03C 10/16 Halogen containing crystalline phase

Abstract

A glass-ceramic which is excellent in mechanical strength, cutting processability and chemical durability and suitable for the production of an artificial dental crown and a mold, the glass-ceramic containing, by weight percentage, 2 to 17% of CaO, 0 to 5% of K₂ O, 0 to 4% of Na₂ O, the total content of K₂ O and Na₂ O being 0.5-7%, 15 to 35% of MgO, 30 to 49% of SiO₂, 2 to 15% of ZrO₂ and not more than 14% (calculated as F) of fluorine, and having a zirconia crystal and a mica crystal precipitated.

Claims

1. A glass-ceramic containing, by weight percentage,

View Dependent Claims (2, 3, 4, 5, 6)

2. A glass-ceramic according to claim 1, wherein the fluorine is contained in an amount of 1.5 to 14% by weight.

3. A glass-ceramic according to claim 1, wherein the CaO is contained in an amount of 5 to 15% by weight, the K₂ O is contained in an amount of 1 to 3.5% by weight, the Na₂ O is contained in an amount of 0.5 to 1.8% by weight, the total amount of the K₂ O and the Na₂ O is 1.5 to 5.3% by weight, MgO is contained in an amount of 19 to 30% by weight, the SiO₂ is contained in an amount of 40 to 49% by weight, the Al₂ O₃ is contained in an amount of 7 to 17% by weight, the ZrO₂ is contained in an amount of 3 to 12% by weight, and the fluorine is contained in an amount of 7 to 14% by weight.

4. A glass-ceramic according to claim 1, which further contains not more than 5% by weight of at least one oxide selected from SrO, TiO₂, Nb₂ O₅, Ta₂ O₅ and Y₂ O₃.

5. A glass-ceramic according to claim 1, which further has at least one precipitated crystal selected from an enstatite crystal, an akermanite crystal, a diopside crystal, an anorthite crystal, a richterite crystal and a forsterite crystal.

6. An artificial dental crown, which is formed from the glass-ceramic recited in claim 1.