Dental restorations using nanocrystalline materials and methods of manufacture

• US 7,655,586 B1
• Filed: 05/28/2004
• Issued: 02/02/2010
• Est. Priority Date: 05/29/2003
• Status: Active Grant

• Current Assignee: Ivoclar Vivadent AG
• Original Assignee: Pentron Ceramics, Inc.
• Inventors: Brodkin, Dmitri, Gamarnik, Moisey Y.
• Primary Examiner(s): Lorengo; Jerry
• Assistant Examiner(s): Wiese; Noah S
• Application Number:
  US10/857,482
• Publication Number:
  US 20100047743A1
• Time in Patent Office: 2,076 Days
• Field of Search: 501102-105, 501/127, 106/35, 433218-221, 433/201.1, 433/202.1
• US Class Current: 501/103
• CPC Class Codes: A61C 13/0006 Production methods
• CPC Class Codes: A61C 13/081 Making teeth by casting or moulding
• CPC Class Codes: A61C 13/083 Porcelain or ceramic teeth A61C13/081 takes precedence; preparations A61K6/80
• CPC Class Codes: B22F 3/12 Both compacting and sintering by forging B22F3/17
• CPC Class Codes: B22F 3/14 simultaneously
• CPC Class Codes: B22F 3/22 for producing castings from a slip
• CPC Class Codes: B22F 3/225 by injection molding
• CPC Class Codes: B33Y 70/10 Composites of different types of material, e.g. mixtures of ceramics and polymers or mixtures of metals and biomaterials
• CPC Class Codes: B33Y 80/00 Products made by additive manufacturing
• CPC Class Codes: B82Y 30/00 Nanotechnology for materials or surface science, e.g. nanocomposites
• CPC Class Codes: C01G 25/00 Compounds of zirconium
• CPC Class Codes: C01P 2004/64 Nanometer sized, i.e. from 1-100 nanometer
• CPC Class Codes: C04B 2235/3206 Magnesium oxides or oxide-forming salts thereof
• CPC Class Codes: C04B 2235/3217 Aluminum oxide or oxide forming salts thereof, e.g. bauxite, alpha-alumina
• CPC Class Codes: C04B 2235/3225 Yttrium oxide or oxide-forming salts thereof
• CPC Class Codes: C04B 2235/3229 Cerium oxides or oxide-forming salts thereof
• CPC Class Codes: C04B 2235/3232 Titanium oxides or titanates, e.g. rutile or anatase
• CPC Class Codes: C04B 2235/3241 Chromium oxides, chromates, or oxide-forming salts thereof
• CPC Class Codes: C04B 2235/3246 Stabilised zirconias, e.g. YSZ or cerium stabilised zirconia
• CPC Class Codes: C04B 2235/3251 Niobium oxides, niobates, tantalum oxides, tantalates, or oxide-forming salts thereof
• CPC Class Codes: C04B 2235/3262 : Manganese oxides, manganates, rhenium oxides or oxide-forming salts thereof, e.g. MnO
• CPC Class Codes: C04B 2235/3279 : Nickel oxides, nickalates, or oxide-forming salts thereof
• CPC Class Codes: C04B 2235/3418 : Silicon oxide, silicic acids or oxide forming salts thereof, e.g. silica sol, fused silica, silica fume, cristobalite, quartz or flint
• CPC Class Codes: C04B 2235/5409 : expressed by specific surface values
• CPC Class Codes: C04B 2235/5427 : millimeter or submillimeter sized, i.e. larger than 0,1 mm
• CPC Class Codes: C04B 2235/5436 : micrometer sized, i.e. from 1 to 100 micron
• CPC Class Codes: C04B 2235/5454 : nanometer sized, i.e. below 100 nm
• CPC Class Codes: C04B 2235/5472 : Bimodal, multi-modal or multi-fraction
• CPC Class Codes: C04B 2235/549 : the particle size being expressed by crystallite size or primary particle size
• CPC Class Codes: C04B 2235/6022 : Injection moulding
• CPC Class Codes: C04B 2235/6023 : Gel casting
• CPC Class Codes: C04B 2235/6026 : Computer aided shaping, e.g. rapid prototyping
• CPC Class Codes: C04B 2235/6027 : Slip casting
• CPC Class Codes: C04B 2235/604 : Pressing at temperatures other than sintering temperatures
• CPC Class Codes: C04B 2235/612 : Machining
• CPC Class Codes: C04B 2235/6562 : Heating rate
• CPC Class Codes: C04B 2235/6565 : Cooling rate
• CPC Class Codes: C04B 2235/667 : Sintering using wave energy, e.g. microwave sintering
• CPC Class Codes: C04B 2235/668 : Pressureless sintering
• CPC Class Codes: C04B 2235/77 : Density
• CPC Class Codes: C04B 2235/785 : Submicron sized grains, i.e. from 0,1 to 1 micron
• CPC Class Codes: C04B 2235/94 : Products characterised by their shape
• CPC Class Codes: C04B 2235/9615 : Linear firing shrinkage
• CPC Class Codes: C04B 2235/9653 : Translucent or transparent ceramics other than alumina
• CPC Class Codes: C04B 35/486 : Fine ceramics
• CPC Class Codes: C04B 35/62695 : Granulation or pelletising devices for shaping artificial aggregates from ceramic mixtures B28B1/004
• CPC Class Codes: C04B 35/632 : Organic additives
• CPC Class Codes: C04B 35/638 : Removal thereof
• CPC Class Codes: C04B 35/645 : Pressure sintering

Abstract

Dental articles are produced using relatively low sintering temperatures to achieve high density dental articles exhibiting strengths equal to and greater than about 700 MPa. Ceramic powders comprised of nanoparticulate crystallites are used to manufacture dental articles. The ceramic powders may include sintering agents, binders and other similar additives to aid in the processing of the ceramic powder into a dental article. The ceramic powders may be processed into dental articles using various methods including, but not limited to, injection molding, gel-casting, slip casting, or electroforming, hand, cad/camming and other various rapid prototyping methods. The ceramic powder may be formed into a suspension, pellet, feedstock material or a pre-sintered blank prior to forming into the dental article.

Claims

1. A dental article comprising:

a single component yttria-stabilized tetragonal zirconia ceramic material having grains of average grain size exceeding 100 nanometers and not exceeding about 400 nanometers, wherein the theoretical density of the ceramic material is known;

wherein the ceramic material is fabricated of particulate material consisting essentially of ceramic crystallites with an average size of less than about 20 nm;

wherein the particulate material is sintered without application of external pressure at a temperature less than about 1300°

C.;

wherein the ceramic material has a final density exceeding 95% and less than 97% of the theoretical density of the ceramic material; and

wherein the ceramic material exhibits at least 30% relative transmission of visible light when measured through a thickness of about 0.3 to about 0.5 mm.

2. The dental article of claim 1 wherein the sintering of the particulate material at temperatures less than about 1300°

C. comprises furnace sintering or microwave sintering to densities exceeding 95% of the theoretical density.

3. The dental article of claim 1 wherein the sintering of the particulate material at temperatures less than about 1300°

C. comprises sintering at a temperature less than about 1200°

C. to densities exceeding 95% of the theoretical density.

4. The dental article of claim 1 wherein the sintering of the particulate material at temperatures less than about 1300°

C. comprises sintering at temperature less than about 1100°

C. to densities exceeding 95% of the theoretical density.

5. The dental article of claim 1 wherein the flexural strength is equal to or greater than about 800 MPa.

6. The dental article claim 1 wherein the particulate material is in the form of free-flowing powder, pre-sintered blanks, a suspension, slurry, slip, gel, pellets or feedstock.

7. The dental article of claim 1 wherein the dental article is formed by injection molding, heat pressing, hot pressing, gel-casting, slip casting, slurry casting, pressure casting, direct coagulation, colloidal spray deposition, dipping, or electroforming the particulate material.

8. The dental article of claim 1 wherein the dental article is selected from the group consisting of orthodontic retainers, bridges, space maintainers, tooth replacement appliances, splints, crowns, partial crowns, dentures, posts, teeth, jackets, inlays, onlays, facings, veneers, facets, implants, cylinders, abutments and connectors.

9. The dental article of claim 1 wherein the ceramic material further comprises alumina, titania, silica, magnesia, ceria or mixtures thereof in solid solution.

10. The dental article of claim 1 wherein forming the particulate material into the dental article is performed by hand, by CAD/CAM methods or by rapid prototyping methods.

11. The dental article of claim 1 wherein forming of the particulate material into the dental article is performed using replicas, molds, dies, substrates, or shells produced by rapid prototyping methods.

12. The dental article of claim 1 wherein the ceramic material exhibits at least 30% relative transmission of visible light when measured through a thickness of about 0.4 mm.

13. The dental article of claim 1 wherein the ceramic material further comprises a sintering aid, a grain growth inhibitor or a combination thereof.

14. The dental article of claim 13 wherein the sintering aid comprises Si, Al, Mg, Zr, Ce, Ta, oxides thereof or a combination thereof.

15. The dental article of claim 13 wherein the grain growth inhibitor comprises Cr, Ti, Ni, Mn, oxides thereof or a combination thereof.

16. A dental article comprising:

a single component yttria-stabilized tetragonal zirconia ceramic material having grains of average grain size exceeding 100 nanometers and not exceeding about 400 nanometers, wherein the theoretical density of the ceramic material is known;

wherein the ceramic material is fabricated of particulate material consisting essentially of ceramic crystallites with an average size of less than about 20 nm;

wherein the particulate material is sintered without application of external pressure at a temperature less than about 1300°

C.;

wherein the ceramic material has a density exceeding 95% of the theoretical density of the ceramic material;

wherein the final grain size is about 10-20 times larger than the ceramic crystallite size and the final pore size does not exceed the size of the ceramic crystallite size; and

wherein the ceramic material exhibits at least 30% relative transmission of visible light when measured through a thickness of about 0.3 to about 0.5 mm.