U.S. patent application number 10/347535 was filed with the patent office on 2003-10-02 for high-strength dental restorations.
Invention is credited to Brodkin, Dmitri, Daskalon, Gregg, Karmaker, Ajit, Panzera, Carlino, Panzera, Paul, Prasad, Arun, Schulman, Martin L., Zammarieh, Elie.
Application Number | 20030183964 10/347535 |
Document ID | / |
Family ID | 28457904 |
Filed Date | 2003-10-02 |
United States Patent
Application |
20030183964 |
Kind Code |
A1 |
Daskalon, Gregg ; et
al. |
October 2, 2003 |
High-strength dental restorations
Abstract
High strength ceramic components for use in dental applications
are provided wherein one or more layers of ceramic material is
disposed on a high strength ceramic component to provide a dental
restoration. The ceramic material may be applied in the form of
powder, putty, tape a pellet.
Inventors: |
Daskalon, Gregg; (Orange,
CT) ; Brodkin, Dmitri; (West Orange, NJ) ;
Karmaker, Ajit; (Wallingford, CT) ; Zammarieh,
Elie; (Wallingford, CT) ; Schulman, Martin L.;
(Orange, CT) ; Prasad, Arun; (Cheshire, CT)
; Panzera, Carlino; (Hillsborough, NJ) ; Panzera,
Paul; (Mt. Holly, NJ) |
Correspondence
Address: |
Pentron Laboratory
Technologies, LLC
53 North Plains Industrial Road
Wallingford
CT
06492
US
|
Family ID: |
28457904 |
Appl. No.: |
10/347535 |
Filed: |
January 17, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10347535 |
Jan 17, 2003 |
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09669348 |
Sep 26, 2000 |
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6533969 |
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09669348 |
Sep 26, 2000 |
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09330665 |
Jun 11, 1999 |
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6413660 |
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60089150 |
Jun 12, 1998 |
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60094612 |
Jul 3, 1998 |
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Current U.S.
Class: |
264/16 ; 106/35;
264/19; 433/215 |
Current CPC
Class: |
A61C 13/26 20130101 |
Class at
Publication: |
264/16 ; 264/19;
433/215; 106/35 |
International
Class: |
A61C 013/00; A61C
013/08 |
Claims
What is claimed is:
1. A dental restorative material comprising: a high strength
ceramic component; and one or more layers of ceramic material
disposed on the high strength ceramic component.
2. The dental material of claim 1 wherein the high-strength ceramic
component is comprised of at least one of alumina, zirconia,
SIALON, mullite, titanium oxide, magnesium oxide, and mixtures
thereof.
4. The dental material of claim 3 wherein the one or more layers of
ceramic material has a thermal expansion that is slightly lower
than a thermal expansion of the high strength ceramic
component.
5. The dental material of claim 3 wherein the ceramic layer is
selected from silica, silicates, aluminates, phosphates, fluorates,
aluminosilicates, silica-rich glasses, zirconates, titanates and
mixtures thereof.
6. The dental material of claim 5 wherein the silicates comprise
lithium disilicate.
7. A method of manufacturing a dental restoration comprising:
providing a high strength ceramic component; applying one or more
layers of ceramic material on the high strength ceramic component
to form the dental restoration.
8. The method of claim 7 further comprising modifying the high
strength ceramic component by grinding or carving to the desired
shape prior to applying one or more layers of ceramic material
thereon.
9. The method of claim 7 wherein the high strength ceramic
component is comprised of at least one of alumina, zirconia,
SIALON, mullite, titanium oxide, magnesium oxide and mixtures
thereof.
10. The method of claim 7 wherein the one or more layers of ceramic
material layer comprises a material selected from silica,
silicates, aluminates, phosphates, fluorates, aluminosilicates,
silica-rich glasses, zirconates, titanates and mixtures
thereof.
11. The method of claim 10 wherein the silicates comprise lithium
disilicate.
12. The method of claim 7 wherein the one or more layers of ceramic
material are applied by sputtering, chemical vapor deposition, ion
bombardment or vacuum deposition.
13. The method of claim 7 wherein the one or more layers of ceramic
material are applied on the ceramic component by pressing.
14. The method of claim 13 wherein pressing is selected from hot
pressing by machine, cold pressing by machine or application of
pressure by hand.
15. The method of claim 13 wherein the one or more layers of
ceramic material are fused to the ceramic component during
pressing.
16. The method of claim 7 wherein the one or more layers of ceramic
material are provided in the form of tape, putty or powder.
17. The method of claim 7 further comprising etching or abrading
the high strength ceramic component prior to application of one or
more layers of ceramic material.
18. The dental material of claim 7 wherein the high strength
ceramic component is in the shape of a bar, pontic, block, or
rod.
19. The dental restorative material of claim 1 selected from an
orthodontic appliance, bridge, space maintainer, tooth replacement
appliance, splint, crown, partial crown, denture, post, tooth,
jacket, inlay, onlay, facing, veneer, facet, implant, abutment,
cylinder, or connector.
20. A method of making a dental restoration comprising: preparing a
wax pattern of the desired dental restoration; wherein the wax
pattern is built around a high strength ceramic component leaving
one or more sections of the high strength ceramic component
uncovered; surrounding the wax pattern with investment material;
burning out the wax to provide a mold for the dental restoration;
filling the mold with a first ceramic material; and sintering the
first ceramic material to provide a dental restoration.
21. The method of claim 20 further comprising removing the dental
restoration from the mold and applying a second ceramic material or
a composite material to the one or more uncovered sections of the
high strength ceramic component and sintering the second ceramic
material or curing the composite material.
22. The method of claim 20 wherein the high strength ceramic
component comprises zirconia and the first ceramic material
comprises lithium disilicate.
23. The method of claim 21 wherein the second ceramic material
comprises lithium disilicate.
24. The method of claim 21 wherein the composite material comprises
particulate filled composite material.
25. The method of claim 21 wherein filling the mold with a first
ceramic material and sintering the first ceramic material to
provide a dental restoration comprises pressing a ceramic pellet
into the mold space and simultaneously sintering the pressed
ceramic pellet.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation-in-part of U.S.
application Ser. No. 09/330,665 filed Jun. 11, 1999 which claims
priority to U.S. Provisional Application Serial No. 60/089,150
filed on Jun. 12, 1998 and U.S. Provisional Application Serial No.
60/094,612 filed on Jul. 30, 1998 both which are hereby
incorporated by reference.
TECHNICAL FIELD
[0002] The present invention relates generally to dental
restorations and more specifically to bonding layers for ceramic
components used in dental restorations and methods of making
thereof. The invention is also directed to high strength ceramic
components embedded in composite materials or ceramic materials for
use as dental materials.
BACKGROUND OF THE INVENTION
[0003] Strength and reliability are important factors to consider
when manufacturing dental restorations. Dental restorations must be
able to withstand the normal mastication forces and stresses that
exist within an oral environment. Different stresses are observed
during mastication of different types of food, which can be
experimentally measured by placing, for example, a strain gauge in
inlays on the tooth. Stresses differ depending not only on the type
of food, but also on the individual. For example, stress values may
range from 570 to 2300 lb/inch.sup.2 for a single chewing thrust on
a piece of meat and from 950 to 2400 lb/inch.sup.2 for a single
thrust on a biscuit. The physical properties of dental restorations
must be adequate to withstand the stresses applied by the
repetitive forces of mastication.
[0004] Ceramic materials have proven to be reliable in the
fabrication of single unit dental restorations. U.S. Pat. No.
4,798,536 to Katz and an article by Kabbert and Knode entitled
"Inceram: Testing a New Ceramic Material", Vol.4, pp 87-97 (1993)
each disclose ceramic compositions having leucite therein to
provide strength and reliability to dental restorations. The
strength of the materials is in the area of 170 MPa which is much
higher than that of conventional porcelain which exhibits strengths
of about 70 MPa. Nevertheless, the strength and/or toughness values
of the aforementioned ceramic materials may not be adequate for the
fabrication of multiple unit restorations.
[0005] There is a need to provide high strength, ceramic
restorations having structural integrity and reliability and
optimum bonding properties. It is desirable to produce high
strength ceramic restorations which are compatible with a wide
range of cost-effective polymeric based dental materials.
SUMMARY OF THE INVENTION
[0006] These and other objects and advantages are accomplished by
the composition and method of manufacture of the present invention
directed to high strength ceramic components for use in dental
applications. In accordance with one embodiment herein, a bonding
layer is disposed on a ceramic component to increase the bonding
properties of the ceramic component in order that the ceramic
component may better bond to a resin material, ceramic material or
composite material. Moreover, the bonding layer provides strength
to the ceramic component by forming a compressive layer
thereon.
[0007] In accordance with another embodiment herein, a ceramic
component is partially or fully embedded or encapsulated in
composite material. The ceramic component is bonded to the
composite material either by mechanical means, chemical means or
both. The composite material may be placed directly on the ceramic
component. Alternatively, the structural component is coated with a
bonding layer to provide adhesion between the composite or like
material and the structural component.
[0008] In accordance with yet another embodiment herein, silicon
dioxide is deposited on the surface of the structural component in
the form of colloidal silica, silane, tetra ethyl orthosilicate, or
a similar silica precursor and heat treated to form a bonding layer
which bonds the structural component to a resin, ceramic or
composite material.
[0009] In accordance with still yet another embodiment, one or more
layers of ceramic material are disposed on a high strength ceramic
component to provide a dental restoration. The ceramic material may
be applied in the form of powder, putty, tape or a pellet.
[0010] The resultant structural component is useful in the
fabrication of dental appliances and restorations such as
orthodontic retainers, bridges, space maintainers, tooth
replacement appliances and splints.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] Features of the present invention are disclosed in the
accompanying drawings, wherein similar reference characters denote
similar elements throughout the several views, and wherein:
[0012] FIG. 1 shows a ceramic bar and bonding layer in accordance
with the present invention;
[0013] FIG. 2 shows a ceramic bar embedded in composite material in
accordance with the present invention;
[0014] FIG. 3 shows a cross-sectional view at line 2-2 of the
component in FIG. 2;
[0015] FIG. 4 shows a ceramic bar with a bonding layer deposited
thereon and embedded in composite material in accordance with the
present invention;
[0016] FIG. 5 shows a ceramic bar partially embedded in composite
material in accordance with the present invention;
[0017] FIG. 6 shows a curved ceramic bar embedded in composite
material in accordance with the present invention;
[0018] FIG. 7 shows a curved ceramic bar embedded in composite
material that follows the contour of the ceramic bar in accordance
with the present invention;
[0019] FIG. 8 shows the size and shape of a bar which was used in
the examples herein;
[0020] FIG. 9 shows a veneering material on the bar of FIG. 8 which
was used in the examples for testing bond strength;
[0021] FIG. 10 shows a dental restoration having a reinforcing
component therein and positioned on a mold;
[0022] FIG. 11 shows a piece of ceramic tape that may be applied on
the reinforcing component in FIG. 10 to form the dental
restoration;
[0023] FIG. 12 shows ceramic putty that may be applied on the
reinforcing component in FIG. 10 to form the dental
restoration;
[0024] FIG. 13 shows ceramic powder that may be applied on the
reinforcing component in FIG. 10 to form the dental
restoration;
[0025] FIG. 14 shows a structural component prior to cutting or
grinding;
[0026] FIG. 15 shows a dental restoration with a reinforcing
component therein;
[0027] FIG. 16 shows a mold with a reinforcing component therein
after the lost wax process and prior to the introduction of ceramic
material by for example, injection molding;
[0028] FIG. 17 shows a dental restoration formed from the die of
FIG. 16; and
[0029] FIG. 18 shows a dilatometer graph showing the coefficients
of thermal expansion for materials used herein.
DETAILED DESCRIPTION OF THE INVENTION
[0030] The present invention is directed to high-strength
structural ceramic components for use in dental applications. In
one embodiment herein, a high-strength structural component is
provided having a bonding layer disposed thereon. The bonding layer
is deposited on the ceramic component to increase the bonding
properties of the ceramic component in order that the ceramic
component may better bond to a resin material, ceramic material or
composite material such as commercially available Sculpture.RTM.
composite from Jeneric/Pentron, Inc., Wallingford, Conn. or
commercially available OPC.RTM. porcelain from Jeneric/Pentron,
Inc., Wallingford, Conn. or lithium disilcate glass-ceramic
material. Moreover, the bonding layer provides strength to the
ceramic component by forming a compressive layer thereon. The
resultant structural component is useful in the fabrication of
dental appliances and restorations such as orthodontic retainers,
bridges, space maintainers, tooth replacement appliances and
splints and further as restorations as set forth in U.S. Pat. No.
5,614,330 to Panzera et al., U.S. Pat. Nos. 4,717,341 and 4,894,012
to Goldberg, and commonly assigned U.S. Pat. No. 6,120,591, all of
which are incorporated by reference herein.
[0031] The structural components may be fabricated of a high
strength ceramic material such as alumina, zirconia, SIALON,
mullite, titanium oxide, magnesium oxide and composites or mixtures
thereof. The flexural strength of the ceramic components is
typically greater than about 400 MPa and preferably in the range of
about 500 MPa to about 1200 MPa. The structural components are
preferably in the form of bars or pontics. The bars may be of any
cross-sectional configuration effective to provide strength and
stiffness to the finished dental appliance. Examples of
cross-sectional configurations of the bars include square,
rectangular, triangular, rhomboidal, ovoidal, and cylindrical
shapes. The bars may be straight or curved depending upon the
placement or use thereof.
[0032] In accordance with one embodiment of the method of the
invention, the structural components are coated with a bonding
layer to provide adhesion between a resin or like material and the
structural component. It is preferable that the bonding layer be
able to easily bond to a coupling agent such as a silane compound.
Suitable bonding layers include but are not limited to silica,
silicates, aluminates, phosphates, fluorates, aluminosilicates,
silica-rich glasses, zirconates and titanates. One preferable
silicate material to be used as the bonding layer comprises lithium
disilicate such as material used to make commercially available
OPC.RTM. 3GTM ceramic pellets available from Jeneric/Pentron Inc.,
Wallingford, Conn. Preferably, silica containing materials such as
porcelain materials such as commercially available ColorMatch.RTM.
porcelain from Jeneric/Pentron Inc., Wallingford, Conn. and
Vitadurn.TM. porcelain from Vita Zahnfabrik, Bad Sackingen, Germany
or silica are used as the bonding layer. The layer may be applied
in any known manner including, but not being limited to, a sol/gel
deposition followed by pyrolysis, fusing, sputtering, chemical
vapor deposition, ion bombardment, and vacuum deposition. If the
bonding layer is fused to the structural component, the fusion
temperature should be lower than that of the structural component.
The fusion temperature of the bonding material is typically in the
range of about 400.degree. C. to about 1500.degree. C. Moreover, it
is preferable that the bonding layer has a coefficient of thermal
expansion slightly lower than that of the structural component.
Furthermore, it is desirable that the bonding layer exhibits good
wetting properties.
[0033] In a preferred embodiment herein, the materials set forth
above that are used as the bonding layer may be applied to the
structural component and used alone as the outer layer to make a
core of a dental restoration without the addition of other
materials. One or more layers of material may be applied in the
form of a pellet, powder, putty or tape. The layer or layers are
applied at thickness in the range from about 0.1 to about 8.0 mm
and more preferably from about 0.3 to about 5.0 mm and most
preferably from about 0.4 to about 1.5 mm. Commonly owned,
copending U.S. patent application Ser. No. 09/653,377 filed Sep. 1,
2000 is directed to putty and tape formulations and is hereby
incorporated by reference. Moreover, the material may be in powder
form or pellet form such as those materials disclosed in copending,
commonly owned U.S. patent application Ser. No. 09/458,919 filed
Dec. 10, 1999 and U.S. patent application Ser. No. 09/640,941 filed
Aug. 17, 2000 which are hereby incorporated by reference. Depending
on the form of the material to be applied to the structural
component, the method of application may include any known method
such as a sol/gel deposition followed by pyrolysis, fusing,
sputtering, chemical vapor deposition, ion bombardment, vacuum
deposition, hammering, bending, wrapping, shaping and pressing, by
application of pressure by hand or with the use of utensils or
pressing equipment such as an isostatic, hot or cold pressing
machine. In one example of this preferred embodiment, zirconia bars
are used as reinforcement for dental restorations. Zirconia bars
may be ground by using diamond and alumina tools to form the
desired shape. Lithium disilicate glass-ceramic material such as
OPC.RTM.3G.TM. pressable ceramic available from Jeneric/Pentron
Inc., Wallingford, Conn., is applied to the zirconia bar by
pressing the material into a mold fabricated around the zirconia
bar.
[0034] In accordance with a second embodiment of the method of the
invention, silicon dioxide is deposited on the surface of the
structural component in the form of colloidal silica, silane, tetra
ethyl orthosilicate, or a similar silica precursor. The silicon
dioxide may be pure silicon dioxide. The component with the layer
thereon is heated to a sufficiently high temperature in the range
of about 400.degree. C. to about 1400.degree. C., preferably about
600.degree. C. to about 1300.degree. C. to allow the silica to
react with the structural component to form a bond. For example, if
the structural component comprises alumina, the silica reacts
therewith to form a thin layer of mullite. If the structural
component comprises zirconia, the silica reacts therewith to form
zircon. The mullite and zircon each possess a lower thermal
expansion than the alumina and zirconia, respectively, thereby
forming a compressive layer on the structural components further
increasing the strength.
[0035] In accordance with the method of the invention, the bonding
layer can be abraded or etched by methods known in the art such as
sand blasting or acid etching. The layer may then be primed with a
coupling agent. U.S. Pat. Nos. 5,444,104, 4,547,531 and 4,544,359
all to Waknine, which are incorporated by reference herein, discuss
suitable etching and priming procedures. Suitable coupling agents
include silane compounds such as organo-silane agents. Exemplary
silane agents include gamma-methacryloxy propyltrimethoxysilane
which is available from Osi Specialties, Inc., Friendly, W. Va.
under the name Silquest A-174, gamma-aminopropyl triethoxysilane,
vinyl trichlorosilane and styrylamine functional silane.
[0036] In accordance with another embodiment herein, the present
invention is directed to a high-strength structural ceramic
component partially or fully embedded or encapsulated in composite
material. The composite material may be any known composite
material such as a resin or polymeric material combined with
particulate and/or fiber material. Preferably, the composite is a
polymeric material having particulate therein such as commercially
available Sculpture.RTM. composite available from Jeneric/Pentron
Inc., Wallingford, Conn., or polymeric material reinforced with
fiber and/or particulate such as commercially available
FibreKor.RTM. composite from Jeneric/Pentron, Inc., Wallingford,
Conn. The ceramic component is bonded to the composite material
either by mechanical means, chemical means or both. Mechanical
bonding occurs after the ceramic component is embedded in the
composite material and the composite material is cured. To aid in
the mechanical bonding of the composite material to the ceramic
component, the ceramic component may be treated prior to covering
with composite material. Treatment may include etching, abrading
and the like. Chemical bonding of the ceramic to composite material
may involve organically modifying the surface of the ceramic such
as through application of a silane or other coupling agent to the
surface of the ceramic. Preferably, the composite material
completely encapsulates the ceramic component. This then allows for
easier carving or grinding or other similar modification to the
component to form the shape desired since bridges, space
maintainers, tooth replacement appliances and splints each require
some customization to adequately fit within the patient's mouth.
The ceramic component may be difficult to carve into complicated or
difficult shapes. The composite material thereon allows for such
modification. The resultant structural component is useful in the
fabrication of dental appliances and restorations such as
orthodontic retainers, bridges, space maintainers, tooth
replacement appliances and splints and further as restorations set
forth in U.S. Pat. No. 5,614,330 to Panzera et al., U.S. Pat. Nos.
4,717,341 and 4,894,012 to Goldberg, and commonly assigned U.S.
Pat. No. 6,120,591, all of which are incorporated by reference
herein.
[0037] In accordance with yet another embodiment of the method of
the invention, the composite material is placed directly on the
ceramic component. The composite material may be wound around the
ceramic component or molded, pressed or deposited in any known
fashion or method. The composite material may be oriented in one or
more directions. For example, if fiber reinforced composite
material is used, it may be wound around the ceramic component. One
layer may be oriented perpendicular to the length of the ceramic
component and the next layer may be oriented parallel to the length
of the ceramic component, alternating the direction as layers are
applied thereto. Commercially available Fibrekor.RTM. fiber
reinforced composite from Jeneric/Pentron Inc., Wallingford, Conn.
may be used to build the fiber reinforced composite around the
ceramic component.
[0038] In accordance with an alternative embodiment of the method
of the invention, prior to partially or fully encapsulating or
embedding the structural component in composite material, the
structural component is coated with a bonding layer as set forth
above to provide adhesion between the composite material and the
structural component. Additionally, the bonding layer provides
strength to the ceramic component by forming a compressive layer
thereon. A coupling agent may be applied to the structural
component prior to application of the bonding layer. It is
preferable that the bonding layer be able to easily bond to a
coupling agent such as a silane compound. Suitable bonding layers
include but are not limited to silica, silicates, aluminates,
phosphates, fluorates, aluminosilicates, silica-rich glasses,
zirconates and titanates. The layer may be applied in any known
manner including, but not being limited to, fusing, sputtering,
chemical vapor deposition, ion bombardment, and vacuum deposition.
If the bonding layer is fused to the structural component, the
fusion temperature should be lower than that of the structural
component. Moreover, it is preferable that the bonding layer has a
coefficient of thermal expansion slightly lower than that of the
structural component. Furthermore, it is desirable that the bonding
layer exhibits good wetting properties.
[0039] In accordance with yet another embodiment of the method of
the invention, prior to partially or fully encapsulating or
embedding the structural component in composite material, silicon
dioxide is deposited on the surface of the structural component in
the form of colloidal silica, silane, tetra ethyl orthosilicate, or
a similar silica precursor. The silicon dioxide may be pure silicon
dioxide. The component with the layer thereon is heated to a
sufficiently high temperature to allow the silica to react with the
structural component to form a bond. For example, if the structural
component comprises alumina, the silica reacts therewith to form a
thin layer of mullite. If the structural component comprises
zirconia, the silica reacts therewith to form zircon. The mullite
and zircon each possess a lower thermal expansion than the alumina
and zirconia, respectively, thereby forming a compressive layer on
the structural components further increasing the strength.
[0040] The composite material used above may be fully or partially
polymerized using photo, chemical or thermal means under controlled
pressure or atmospheric pressure. The resin or polymeric component
can be selected from those known in the art of dental materials,
including those listed in commonly assigned U.S. Pat. No.
6,013,694, which is incorporated by reference herein. The polymeric
matrix materials include but are not limited to expandable
monomers, liquid crystal monomers, ring-opening monomers,
polyamides, acrylates, polyesters, polyolefins, polymides,
polyarylates, polyurethanes, vinyl esters or epoxy-based materials.
Other polymeric matrices include styrenes, styrene acrylonitriles,
ABS polymers, polysulfones, polyacetals, polycarbonates,
polyphenylene sulfides, and the like. These polymeric matrices are
derived from curing polymeric matrix precursor compositions. Such
precursor compositions are well-known in the art, and may be
formulated as one-part, two-part, or other compositions, depending
on the components.
[0041] Preferred materials include those based on acrylic and
methacrylic monomers, for example those disclosed in U.S. Pat. No.
3,066,112, No. 3,179,623, and No. 3,194,784 to Bowen; U.S. Pat. No.
3,751,399 and No. 3,926,906 to Lee et al.; and commonly assigned
U.S. Pat. No. 5,276,068 to Waknine and U.S. Pat. No. 5,969,000, all
of which are herein incorporated by reference in their entirety. E
specially preferred methacrylate monomers include the condensation
product of bisphenol A and glycidyl methacrylate,
2,2'-bis[4-(3-methacryloxy-2-hydroxy propoxy)-phenyl]propane
(hereinafter abbreviated BIS-GMA), the condensation product of
ethoxylated bisphenol A and glycidyl methacrylate, (hereinafter
EBPA-DMA), and the condensation product of 2 parts
hydroxymethylmethacrylate and 1 part triethylene glycol
bis(chloroformate) (hereinafter PCDMA). Polyurethane
dimethacrylates (hereinafter abbreviated to PUDMA) are also
commonly-used principal polymers suitable for use in the present
invention.
[0042] The polymeric matrix precursor composition may further
comprise a co-polymerizable diluent monomer. Such monomers are
generally used to adjust the viscosity of the polymerizable
composition, which affects wettability of the composition. Suitable
diluent monomers include, without limitation, hydroxyalkyl
methacrylates, such as 2-hydroxyethyl methacrylate, 1,6-hexanediol
dimethacrylate, and 2-hydroxypropyl methacrylate; glyceryl
dimethacrylate; ethyleneglycol methacrylates, including
ethyleneglycol methacrylate, diethyleneglycol dimethacrylate,
triethyleneglycol dimethacrylate and tetraethyleneglycol
dimethacrylate; or diisocyanates, such as 1,6-hexamethylene
diisocyanate. Triethyleneglycol dimethacrylate (TEGDMA) is
particularly preferred for use in the present invention.
[0043] The polymeric matrix precursor composition typically
includes polymerization initiators, polymerization accelerators,
ultra-violet light absorbers, anti-oxidants, fluorescent whitening
agents, and other additives well known in the art. The polymer
matrices may be visible light curing, self-curing, dual curing, and
vacuum-, heat-, and pressure-curable compositions as well as any
combination thereof. Visible light curable compositions employ
light-sensitive compounds such as benzil diketones, and in
particular, dl-camphorquinone in amounts ranging from about 0.05 to
0.5 weight percent. UV absorbers are particularly desirable in the
visible light curable compositions in order to avoid discoloration
of the resin form any incident ultraviolet light. Suitable UV
absorbers are the various benzophenones, particularly UV-9 and
UV-5411 available from American Cyanamid Company, and
benzotriazoles known in the art, particularly
2-(2'-hydroxy-5'-methylphenyl)-benzotriazole, sold under the
trademark TINUVIN P by Ciba-Geigy Corporation, Ardsley, N.Y. in
amounts ranging from about 0.05 to about 5.0 weight percent.
[0044] In the self-curing compositions, a polymerization
accelerator may be included in the polymerizable monomer
composition. The polymerization accelerators suitable for use
include the various organic tertiary amines well known in the art,
generally aromatic tertiary amines, such as dimethyl-p-toluidine,
dihydroxyethyl-p-toluidine and the like, in amounts ranging from
about 0.05 to about 4.0 weight percent, and generally acrylate
derivatives such as dimethylaminoethyl methacrylate and
particularly, diethylaminoethyl methacrylate in amounts ranging
from about 0.05 to 0.5 weight percent.
[0045] The heat and pressure curable compositions include, in
addition to the monomeric components, a heat cure initiator such as
benzoyl peroxide, 1,1'-azobis(cyclohexanecarbonitrile), or other
suitable free radical initiators. Particularly suitable free
radical initiators are lauroyl peroxide, tributyl hydroperoxide,
AIBN and, more particularly benzoyl peroxide or
1,1'-azobis(cyclohexanecarbonitrile).
[0046] The polymeric matrix may further comprise at least one
filler known in the art and used in dental restorative materials,
including reinforcing fibers as set forth in U.S. Pat. Nos.
4,717,341 and 4,894,012 to Goldberg et al, and copending commonly
assigned U.S. application Ser. No. 09/270,853 filed Mar. 17, 1999,
all of which are incorporated by reference herein in their
entirety. Suitable fillers are those capable of being covalently
bonded to the polymeric matrix itself or to a coupling agent that
is covalently bonded to both. Examples of suitable filling
materials include but are not limited to those known in the art
such as silica, silicate glass, quartz, barium silicate, strontium
silicate, barium borosilicate, strontium borosilicate,
borosilicate, lithium silicate, amorphous silica, ammoniated or
deammoniated calcium phosphate and alumina, zirconia, tin oxide,
and titania. Particularly suitable fillers for dental filling-type
materials prepared in accordance with this invention are those
having a particle size ranging from about 0.1-5.0 microns with a
silicate colloid of 0.001 to about 0.07 microns and prepared by a
series of milling steps comprising wet milling in an aqueous
medium, surface etch milling and silanizing milling in a silane
solution. Some of the aforementioned inorganic filling materials
are disclosed in commonly-assigned U.S. Pat. Nos. 4,544,359 and No.
4,547,531 to Waknine, the pertinent portions of which are
incorporated herein by reference.
[0047] The reinforcing fiber element of the polymeric composite
preferably comprises glass, carbon, graphite, polyaramid, or other
fibers known in the art, such as polyesters, polyamides, and other
natural and synthetic materials compatible with the polymeric
matrix. Some of the aforementioned fibrous materials are disclosed
in commonly assigned copending U.S. Pat. Nos. 4,717,341, 4,894,012
and 6,013,694, all which are incorporated herein by reference. The
fibers may further be treated, for example silanized, to enhance
the bond between the fibers and the polymeric matrix. The fibers
preferably take the form of long, continuous filaments, although
the filaments may be as short as 3 to 4 millimeters. Shorter fibers
of uniform or random length might also be employed. Preferably, the
fibers are at least partially aligned and oriented along the
longitudinal dimensions of the wire. However, depending on the end
use of the composite material, the fibers may also be otherwise
oriented, including being normal or perpendicular to that
dimension.
[0048] In all embodiments set forth above, the bonding layer may be
applied in any thickness sufficient to create a bond between the
structural component and the outer resin, ceramic or composite
layer. Preferably, the thickness of the bonding layer is about 5
microns to about 100 microns. The layer may be applied to all sides
of the structural component or only those sides which will require
an outer surface layer thereon to form the dental restoration.
Preferably, all sides of the structural component are coated. After
the bonding layer has cured, it can be abraded or etched by methods
known in the art such as sand blasting or acid etching. The layer
may then be primed with a coupling agent. U.S. Pat. Nos. 5,444,104,
4,547,531 and 4,544,359 all to Waknine, which are incorporated by
reference herein, discuss suitable etching and priming procedures.
Suitable coupling agents include silane compounds such as
organo-silane agents. Exemplary silane agents include
gamma-methacryloxy propyltrimethoxysilane which is available from
Osi Specialties, Inc., Friendly, W. Va. under the name Silquest
A-174, gamma-aminopropyl triethoxysilane, vinyl trichlorosilane and
styrylamine functional silane.
[0049] After application of the coupling agent, the structure may
be readily bonded to resin, ceramic or composite material in order
to manufacture a dental restoration or appliance.
[0050] FIGS. 1 through 7 show examples of dental materials
manufactured in accordance with the present invention. FIG. 1 shows
a cross-sectional view of a ceramic component 2 with a bonding
layer 3 thereon and resin material 4 formed on bonding layer 3.
FIG. 2 shows a cross-sectional view of a dental material 10
comprising a ceramic component 12 partially embedded in particulate
filled composite material 14. All sides of component 12 are
embedded except for ends 12a and 12b which are exposed and not
covered by composite material 14. FIG. 3 is a cross-sectional view
of FIG. 2 at line 2-2. FIG. 4 shows a cross-sectional view of a
dental material 16 having a ceramic component 18 covered with a
bonding layer 20 and fully embedded on all sides in a fiber
reinforced composite material 22. FIG. 5 shows a cross-sectional
view of a dental material 24 with a ceramic component 26 partially
embedded in composite material 28. The upper side 26a of ceramic
component 26 is exposed. FIG. 6 shows a cross-sectional view of a
dental material 30 comprising a ceramic component 32 fully embedded
in fiber reinforced composite material 34. FIG. 7 shows a
cross-sectional view of a dental material 36 having a ceramic
component 38 fully embedded in fiber reinforced composite material
40 which follows the contour of the ceramic material 38. In each of
the FIGURES, the coated structural materials shown may be further
modified by grinding, cutting, sawing, machining or likewise
modifying to any shape desired to fabricate a dental appliance or
restoration. The outer composite material is easy to work with in
comparison to the ceramic component which may be difficult to cut
or grind. The outer material may be easily cut to any desired shape
or size.
[0051] FIG. 10 shows a bridge restoration 100 comprising a bar 102
manufactured from a high strength material such as zirconia.
Ceramic material 102 such as lithium disilicate is shown on and
around bar 104 forming the bridge restoration 100. Ceramic material
102 may be applied to bar 104 in the form of a tape 110 as shown in
FIG. 11, putty 120 as shown in FIG. 12, powder 130 as shown in FIG.
13 or a pellet 168 as shown in FIG. 16 and hereinafter described.
FIG. 14 shows zirconia bar 140 which may be ground and or cut to
the desired shape as shown in FIG. 15 to form a dental restoration
150.
[0052] FIG. 16 shows a mold 160 made using the lost wax process
having sprues 162 formed therein to allow material to enter mold
160. A high strength bar 164 is positioned in mold 160 and acts as
a reinforcement component for the dental restoration to be formed.
As shown in FIG. 16, the mold is encased in a refractory die
material 166. Mold 160 does not completely cover bar 164 at points
164t (top) and 164b (bottom) and a high heat refractory material
166 (such as a die material) is in contact at points 164t and 164b
to maintain the position of bar 164 as the wax is burned out and
mold 160 is formed. Mold 160 is subsequently filled with a ceramic
material to form the exterior of the dental restoration, for
example by pressing a pellet of material 168 as shown by the arrow
at the top of FIG. 16. FIG. 17 shows a dental bridge restoration
170 after removal from the mold. Uncovered sections 164t and 164b
will be covered with a ceramic material such as those materials set
forth above that could originally be applied to the bar or a
composite material such as those set forth above, for example,
particulate filled composite material prior to insertion in the
patient's mouth.
[0053] The following examples illustrate the invention.
EXAMPLE 1
[0054] Three-point flexural tests were conducted on zirconia bars
having dimensions of 33 mm.times.4 mm.times.3 mm whereby the 3 mm
side tapers to 2.6 mm and the top of the bar is slightly concave as
shown in FIG. 8. The bars were treated as set forth in the Table 1
below to determine the bonding strength between the bars and the
veneering layer. The veneering layer was applied along the length
of the bar at a span of about 17 mm.times.10 mm.times.10 mm as
shown in FIG. 9. In example 1, zirconia bars without prior
treatment and without a bonding material were tested for strength.
In example 2, zirconia bars were heated and a veneering layer was
applied without an intermediate bonding layer. In example 3,
zirconia bars were heat treated and thereafter coated with a layer
of silane. A veneering layer was thereafter applied. In examples 4
through 6, zirconia bars were coated with a bonding layer and
heat-treated thereafter to fuse the layer thereto. Veneering layers
were then applied to the bonding layer with or without surface
treatment or a coupling agent as set forth in Table 1. Table 1
provides the three-point flexural test results for the various
examples.
1TABLE 1 Bending Bonding Heat Surface Veneering Load Material
Material Treatment Treatment Layer (lbs) 1. Zirconia Bars none none
none none 227 (as received) 2. Zirconia Bars none 960.degree. C.
none Sculpture .RTM. 198 Resin 3. Zirconia Bars none 960.degree. C.
silane Sculpture .RTM. 189 Resin 4. Zirconia Bars Tyspar .TM.
857.degree. C. silane & Sculpture .RTM. 226 porcelain**
thinning Resin liquid 5. Zirconia Bars Vitadurn .TM. 960.degree. C.
none Sculpture .RTM. 210 porcelain*** Resin 6. Zirconia Bars
ColorMatch .RTM. 938.degree. C. silane & Sculpture .RTM. 215
porcelain* thinning Resin liquid *ColorMatch is a registered
trademark of Jeneric/Pentron Inc., Wallingford, CT. **Tyspar is a
trademark of American Thermocraft Corporation, Somerset, NJ.
***Vitadurn is a trademark of Vita Zahnfabrik, Bad Sackingen,
Germany.
[0055] The results in Table 1 show the bond strength obtained
between the zirconia bars and the resin materials when an
intermediate bonding layer is used. Example 1 exhibits the strength
of the zirconia. The bars which were coated with a bonding material
(Examples 4-6) show strengths similar to strengths of the as
received bars of Example 1 which had no prior treatment. When no
bonding layer was used, the bonding strength decreased. Dental
materials and restorations having high strength structural
components are appreciated by the invention wherein a bonding layer
is applied to the ceramic component by fusion, sputtering, chemical
vapor deposition, ion bombardment, vacuum deposition and the like
to achieve a layer to which a resin, composite, ceramic, or like
material will easily bond to.
EXAMPLE 2
[0056] Zirconia bars (length=70 mm, height=4 mm, width tapered from
2.5 mm to 3 mm) received from Friatec Aktiengesellschaft (Division
Frialit-Degussit, Mannheim, Germany) were thinned down using 120
grit silicon carbide sand paper, cut into smaller sections with a
high-speed hand-piece equipped with a diamond wheel and further
shaped using white stone (made from alumina). This tetragonal
zirconia polycrystalline (TZP) material was relatively easily cut
by the diamond wheel and was even lightly shaped by a conventional
white stone made from alumina. It was found also that lithium
disilicate glass-ceramic material (OPC.RTM.3G.TM. ceramic material
available from Jeneric/Pentron Inc.) is not only expansion
compatible to the zirconia (TZP) material but wets and bonds very
well to this zirconia material. To illustrate the application of
these materials for multi unit dental restorations a three-unit
bridge was built on a refractory model made from Polyvest
Refractory Die Material (Whip Mix Corp., Louisville, Ky.) as per
manufacturer instructions. The Polyvest model was soaked in
distilled water for 3 minutes prior to core build-up. Identical
frameworks were fabricated using the -200 mesh powders made from
the lithium disilicate glass-ceramic compositions set forth in
Table 2 below. Average particle size of both powders was about 35
microns. Specifically, the glass-ceramic of composition 2 is
similar to OPC.RTM.3G.TM. pellet material. The powders were mixed
with water to thick paste consistency. The core was built on the
Polyvest refractory die in three consecutive applications as
described below. First, the lithium disilicate powder was applied
on the abutments as a thin coat and fired at a temperature given in
the table below. Second, one of the abutments was built to nearly
full contour with a hole in a proximal surface. The zirconia insert
made as described above was set in a hole and balanced on the die.
After the second bake (at the same temperature as the first bake)
the zirconia insert was permanently fused into one of the
abutments. In the third application both abutments and pontic were
built to complete the required core geometry. After the third bake
at the same temperature, the lithium disilicate core with zirconia
reinforcement was complete. The cores made from compositions 1 and
2 were mounted in epoxy, sectioned and polished through 120 and
400-grit sandpaper. Polished cross-sections were studied using
optical microscope at magnifications of 50.times. and 200.times..
Cores were found to be fully dense. Interface between zirconia and
lithium disilicate material was carefully inspected and no cracks,
bubbles, debonding or delamination were found. One of the bridge
cores (frameworks) made from composition 2 was fully completed
using OPC.RTM.3G.TM. porcelain. The fired three-unit framework
reinforced with the zirconia insert was further overlaid with
OPC.RTM.3G.TM. porcelain. After porcelain was fired, the resulting
bridge was found to be more than adequate in aesthetics and
function. To confirm the thermal expansion compatibility between
lithium disilicate glass ceramics and TZP zirconia the thermal
expansion of both was measured and the resulting expansion curves
overlaid as depicted in FIG. 18. Line 182 depicts the thermal
expansion curve of zirconia. Line 184 depicts the thermal expansion
of composition 1 set forth in Table 2 below. Line 186 depicts the
thermal expansion of composition of composition 2 set forth in
Table 2 below.
2TABLE 2 LithiumDisilcate Glass-Ceramic 1 2 SiO.sub.2 68.7 68.8
B.sub.2O.sub.3 -- 1.2 Al.sub.2O.sub.3 4.8 4.8 CaO 1.0 1.0 BaO 2.8
2.8 Li.sub.2O 14.4 14.4 K.sub.2O 2.2 2.2 Na.sub.2O 1.5 1.4
P.sub.2O.sub.5 3.3 3.3 Tb4O.sub.7 0.7 -- CeO.sub.2 0.7 -- Firing
890.degree. C. .times. 1 min. 880.degree. C. .times. 1 min.
Temperature hold hold
[0057] While various descriptions of the present invention are
described above, it should be understood that the various features
can be used singly or in any combination thereof. Therefore, this
invention is not to be limited to only the specifically preferred
embodiments depicted herein.
[0058] Further, it should be understood that variations and
modifications within the spirit and scope of the invention may
occur to those skilled in the art to which the invention pertains.
Accordingly, all expedient modifications readily attainable by one
versed in the art from the disclosure set forth herein that are
within the scope and spirit of the present invention are to be
included as farther embodiments of the present invention. The scope
of the present invention is accordingly defined as set forth in the
appended claims.
* * * * *