阅读说明：本技术 包含陶瓷纤维和纳米团簇的复合材料、牙科产品、套件盒及其制备和使用方法 (Composite material comprising ceramic fibers and nanoclusters, dental product, kit and methods of making and using the same ) 是由 大卫·M·威尔逊 布雷德利·D·克雷格 马克·B·阿格雷 卡瑞·A·麦克吉 戴蒙·K·海勒 于 2019-09-06 设计创作，主要内容包括：本公开提供了一种复合材料。该复合材料包含：20重量％至40重量％(wt.％)的可聚合组分；6重量％至40重量％的陶瓷纤维；以及30重量％至70重量％的纳米团簇。陶瓷纤维中的每一根陶瓷纤维具有直径和长度,陶瓷纤维具有0.3微米至5微米的算术平均直径,并且陶瓷纤维中的百分之五十(基于陶瓷纤维的总数计)的长度为至少10微米,并且陶瓷纤维中的百分之九十的长度不大于500微米。本公开还提供了一种制备该复合材料的方法。该方法包括获得组分并混合组分以形成复合材料。此外,本公开提供了一种使用复合材料的方法,该方法包括将复合材料放置在牙齿表面附近或牙齿表面上,改变复合材料在牙齿表面附近或牙齿表面上的形状,以及硬化复合材料。此外,本公开提供了牙科产品和套件盒。硬化复合材料可表现出高强度。(The present disclosure provides a composite material. The composite material comprises: 20 to 40 weight percent (wt.%) of a polymerizable component; 6 to 40 wt% of ceramic fibers; and 30 to 70 wt% nanoclusters. Each of the ceramic fibers has a diameter and a length, the ceramic fibers have an arithmetic mean diameter of 0.3 to 5 microns, and fifty percent (based on the total number of ceramic fibers) of the ceramic fibers have a length of at least 10 microns, and ninety percent of the ceramic fibers have a length of no greater than 500 microns. The present disclosure also provides a method of making the composite material. The method includes obtaining components and mixing the components to form a composite material. In addition, the present disclosure provides a method of using a composite material, the method comprising placing the composite material near or on a tooth surface, changing the shape of the composite material near or on the tooth surface, and hardening the composite material. Further, the present disclosure provides dental products and kits. The hardened composite material may exhibit high strength.)

1. A composite material, comprising:

20 to 40 weight percent (wt.%) of a polymerizable component;

6 to 40 wt% of ceramic fibers; and

30 to 70 wt% of nanoclusters,

wherein the weight% value of the composite is based on the total weight of the composite and totals a value of up to 100 weight%, wherein each of the ceramic fibers has a diameter and a length, wherein the ceramic fibers have an arithmetic mean diameter of 0.3 to 5 microns, and wherein fifty percent of the ceramic fibers have a length of at least 10 microns based on the total number of the ceramic fibers and ninety percent of the ceramic fibers have a length of no greater than 500 microns based on the total number of the ceramic fibers.

2. The composite of claim 1, wherein the aspect ratio of the arithmetic mean length of the ceramic fibers to the arithmetic mean diameter of the ceramic fibers is at least 10:1 (mean length: mean diameter).

3. The composite material of claim 2, wherein the aspect ratio is at most 150:1 (average length: average diameter).

4. The composite material of any one of claims 1 to 3, wherein the ceramic fibers have an arithmetic mean diameter of 0.3 to 3 microns or 2 to 5 microns.

5. The composite material of any one of claims 1 to 4, wherein the ceramic fibers have an arithmetic mean length of 50 to 250 micrometers.

6. The composite of any one of claims 1 to 5, wherein the ceramic fibers comprise alumina fibers, alumina-silica fibers, aluminum borosilicate fibers, zirconia-silica fibers, borosilicate glass fibers, silicate fibers modified with alkali or alkaline earth metals, fused silica fibers, leached silica fibers, quartz fibers, glass fibers, or combinations thereof.

7. The composite material of any one of claims 1 to 6, wherein the composite material comprises up to 15 wt% nanoparticles.

8. The composite material of any one of claims 1 to 7, wherein the polymerizable component forms a hardened polymerizable component having a refractive index, and wherein the refractive index value of the ceramic fibers differs from the refractive index of the hardened polymerizable component by a value in the range of 0.1 or less.

9. The composite material of any one of claims 1 to 8, wherein the ceramic fibers have a refractive index value of 1.40 to 1.65.

10. The composite of any of claims 1-9, wherein the composite is formed to have a radial tensile strength (DTS) of 65 megapascals (MPa) or greater, a flexural strength of 170MPa or greater, and 2.50 megapascals square root meters (MPa-m)^1/2) Or greater fracture toughness.

11. The composite of any of claims 1-10, wherein the composite forms a hardened composite having a polish retention of 40 gloss units or greater at 60 ° after 6000 brushing cycles.

12. The composite material of any one of claims 1 to 11, wherein a ratio of an abrasion resistance of a hardened composite material formed from the composite material to an abrasion resistance of a hardened composite material formed from a control composite material is 2.0 or less, wherein the control composite material has the same composition as the composite material except that it does not contain ceramic fibers.

13. A dental product prepared by hardening the composite material according to any of the preceding claims 1 to 12.

14. The dental product of claim 13, wherein the dental product is selected from the group consisting of a dental restoration, a dental adhesive, a dental mill blank, a dental cement, a dental prosthesis, an orthodontic device, an orthodontic adhesive, a dental casting material, an artificial crown, an anterior filling, a posterior filling, a cavity liner, and a dental coating.

15. A method of making a composite material, the method comprising:

obtaining a plurality of components, the plurality of components comprising:

20 to 40 weight percent of a polymerizable component;

6 to 40 wt% of ceramic fibers; and

30 to 70 wt% nanoclusters;

wherein the weight percent value of the composite is based on the total weight of the composite and totals a value of up to 100 weight percent, wherein each of the ceramic fibers has a diameter and a length, wherein the ceramic fibers have an arithmetic mean diameter of 0.3 to 5 microns, and wherein fifty percent of the ceramic fibers have a length of at least 10 microns based on the total number of the ceramic fibers and ninety percent of the ceramic fibers have a length of no greater than 500 microns based on the total number of the ceramic fibers; and

mixing the plurality of components to produce the composite material.

16. A method of using a composite material, the method comprising:

placing the composite material of any one of claims 1 to 12 near or on a tooth surface;

changing the shape of the composite material near or on the tooth surface; and

hardening the composite material.

17. The method of claim 16, further comprising polishing the composite material after hardening the composite material.

18. A kit, the kit comprising:

the composite material according to any one of claims 1 to 12; and

at least one container for containing the composite material.

19. The kit of claim 18, further comprising at least one dental component selected from the group consisting of: cements, adhesives, abrasives, polishes, instruments, software, milling machines, CAD/CAM systems, composites, china, stains, burr, impression materials, dental mill blanks, or combinations thereof.

Technical Field

The present disclosure relates generally to composite materials, and more particularly to composite materials comprising ceramic fibers.

Background

Direct dental restorative materials consist of a curable phase (typically a methacrylate resin), an initiator and a filler system. These materials are typically highly filled with particles, such as nano-sized particles, micro-milled materials, and/or solution grown inorganics. Furthermore, similar compositions made from pre-cured "composites" (e.g., dental mill blanks) have been introduced to the market, where the material is cured in the mouth and formed into a final restorative shape (e.g., inlay, onlay, or crown) via a reduction process (e.g., milling). All of these dental restorative materials have requirements including high strength, high stiffness, and high fracture toughness to function in the oral environment. Especially in large posterior dental restorations, materials with higher fracture toughness are highly desirable.

Attempts have been made to include fibers in dental restorative materials in order to improve their mechanical properties. However, this results in the processing and aesthetic characteristics being affected. The use of fibers unfortunately creates a rigid, "brittle" type of treatment (e.g., shape and feathering) that is difficult to handle. Once cured, the surfaces of these dental restorative materials quickly lose their luster as they wear away on a daily basis. In addition, many of these dental restorative materials produce highly opaque materials due to the refractive index mismatch between the fiber and the resin. This refractive index mismatch leads to less than ideal aesthetic results.

Thus, there is a need in the art for fiber-containing composites, wherein the composites are easy to handle and provide good aesthetic properties, while still providing the necessary mechanical properties for use as dental restorative materials.

Disclosure of Invention

The present disclosure provides a composite material having improved handling characteristics and good aesthetic qualities while still providing the necessary mechanical properties for use as a dental restorative material. More specifically, in a first aspect, a composite material is provided. The composite material comprises: 20 to 40 weight percent (wt.%) of a polymerizable component; 6 to 40 wt% of ceramic fibers; and 30 to 70 wt% nanoclusters. The wt% values of the composite are based on the total weight of the composite and add up to values of 100 wt%. Each of the ceramic fibers has a diameter and a length, the ceramic fibers have an arithmetic mean diameter of 0.3 to 5 microns, and fifty percent of the ceramic fibers have a length of at least 10 microns based on the total number of ceramic fibers, and ninety percent of the ceramic fibers have a length of no greater than 500 microns based on the total number of ceramic fibers.

In a second aspect, a dental product is provided. The dental product is prepared by hardening the composite material according to the first aspect.

In a third aspect, a method of making a composite material is provided. The method includes obtaining a plurality of components and mixing the plurality of components to produce a composite material. The component comprises: 20 to 40 weight percent of a polymerizable component; 6 to 40 wt% of ceramic fibers; and 30 to 70 wt% nanoclusters. The wt% values of the composite are based on the total weight of the composite and add up to values of 100 wt%. Each of the ceramic fibers has a diameter and a length, the ceramic fibers have an arithmetic mean diameter of 0.3 to 5 microns, and fifty percent of the ceramic fibers have a length of at least 10 microns based on the total number of ceramic fibers, and ninety percent of the ceramic fibers have a length of no greater than 500 microns based on the total number of ceramic fibers.

In a fourth aspect, a method of using a composite material is provided. The method comprises the following steps: placing the composite material according to the first aspect near or on a tooth surface; changing the shape of the composite material near or on the tooth surface; and hardening the composite material.

In a fifth aspect, a kit is provided. The kit includes: a composite material according to the first aspect; and at least one container for containing the composite material.

Composites according to at least certain embodiments of the present disclosure may provide hardened composites (e.g., dental products) that exhibit good strength, good polish retention, wear rate, and/or visual appearance.

The above summary of the present disclosure is not intended to describe each disclosed embodiment or every implementation of the present disclosure. The following description more particularly exemplifies illustrative embodiments. Guidance is provided throughout this application through lists of embodiments that can be used in various combinations. In each case, the lists cited are intended as representative groups only and are not to be construed as exclusive lists.

Drawings

FIG. 1 is a Scanning Electron Microscope (SEM) micrograph of a radial tensile strength (DTS) fracture surface of a hardened composite according to the present disclosure.

FIG. 2 is an SEM micrograph of a DTS fractured surface of a comparative hardened composite.

FIG. 3 is an SEM micrograph of a DTS fractured surface of another hardened composite according to the present disclosure.

While the above-identified drawing figures set forth several embodiments of the disclosure, other embodiments are also contemplated, as noted in the specification. The figures are not necessarily to scale. In all cases, this disclosure presents the invention by way of representation and not limitation. It should be understood that numerous other modifications and embodiments can be devised by those skilled in the art, which fall within the scope and spirit of the principles of the invention.

Detailed Description

The present disclosure provides a composite material having improved handling characteristics and good aesthetic qualities while still providing the necessary mechanical properties for use as a dental restorative material. In particular, the composite material comprises a polymerizable component, ceramic fibers, and nanoclusters. The ceramic fibers used in the composite material as described herein have a small diameter. The small diameter of the ceramic fibers in conjunction with the use of nanoclusters surprisingly results in an improvement in both the handling characteristics of the composite and the aesthetic characteristics of the hardened composite upon hardening. Examples of such improved aesthetic properties include hardened composites that are capable of retaining their polish even after being subjected to repeated wear, such as by brushing with toothpaste.

The hardened composite materials of the present disclosure may also have other desirable aesthetic, physical, and mechanical properties. For example, the hardened composite of the present disclosure may have radiopacity, high mechanical strength, and substantial translucency. Radiopacity is a very desirable property for composite materials used in dental applications. The composite material being radiopaque allows the composite material to be inspected using standard dental X-ray equipment, thereby facilitating long-term detection of marginal leakage or caries in tooth tissue adjacent to the hardened composite material.

The hardened composite material can have substantial translucency (e.g., low visual opacity) to visible light. Translucency is desirable so that the hardened composite will have a realistic appearance when used as a dental restorative material. Translucency is desirable if such composites are intended to be hardened or polymerized using visible light-induced photoinitiation, in order to achieve the desired depth of cure (sometimes as much as two millimeters or more), to achieve uniform hardness in the hardened composite, and in response to the physical constraints imposed by the hardening reaction in the mouth (again, this requires that the unhardened composite is typically exposed to a limited angle of light, and that the hardening radiation is provided by a portable instrument). As described herein, translucency of the composite material may be achieved in part by matching the refractive index of the ceramic fibers to the refractive index of the hardened polymerizable component of the composite material.

The practitioner also wants a composite material for dental applications to have good handling properties, as this property means time saving. For example, in dental restorative work, it is desirable that the composite material be easily shaped, contoured, and feathered into a desired shape. Prior to the present disclosure, attempts to use fibers in composites at loadings sufficient to improve mechanical properties have minimized the handling capabilities of the composites. Such attempts to use milled or ground fibers create a type of "fragile" treatment that needs to be avoided by having good handling characteristics and "feathered" characteristics of the dental restorative material. These other composite materials also have "lumps" which make the handling of the material unpredictable and non-uniform.

Unlike these failed attempts, the composite of the present disclosure maintains good handling characteristics with fiber loading sufficient to improve mechanical properties. The composite materials of the present disclosure exhibit a consistent and uniform composition, which enables predictable and uniform processing of the composite materials. In addition, the refractive indices of the ceramic fibers and polymerizable components used in the present disclosure are suitably matched in order to provide substantial translucency (e.g., low visual opacity) and high aesthetic qualities for use as dental restorative materials. Finally, the hardened composite materials of the present disclosure exhibit enhanced fracture toughness and flexural strength due to the presence of the ceramic fibers and nanoclusters, with minimal degradation of the handling or aesthetic properties of the composite material. This is unexpected because the use of fibers is known to degrade both the handling and aesthetic properties of the composite.

Without being bound by theory, it is hypothesized that the combination of the diameter size of the ceramic fibers and the relatively uniform distribution of the ceramic fibers and nanoclusters used in the composite of the present disclosure results in these advantageous properties. The particular diameter range of the ceramic fibers surprisingly results in an improvement in both the handling characteristics of the composite material and the physical characteristics of the hardened composite material upon hardening. Examples of such dental restorative materials with improved physical properties include dental restorative materials that are capable of maintaining their polishing after repeated abrasive contacts.

Glossary

The term "amorphous material" refers to a material derived from the melt and/or vapor phase that is free of long range crystalline structure as determined by X-ray diffraction and/or has an exothermic peak corresponding to the crystallization of the amorphous material as determined by DTA (differential thermal analysis) as described herein by the test named "differential thermal analysis".

The term "ceramic" includes amorphous materials, glasses, crystalline ceramics, glass ceramics, and combinations thereof.

The term "crystalline ceramic" refers to a ceramic material that exhibits a discernible X-ray powder diffraction pattern.

The term "glass" refers to an amorphous material that exhibits a glass transition temperature.

The term "glass-ceramic" refers to a ceramic comprising crystals formed by heat treating an amorphous material.

The term "electron donor" generally refers to a compound having a substituent capable of donating an electron. Suitable examples include, but are not limited to, primary amino, secondary amino, tertiary amino, hydroxyl, alkoxy, aryloxy, alkyl, or combinations thereof.

As used herein, "hardenable" is a description of a material or composition that can be cured (e.g., polymerized or crosslinked) by, for example, removing solvent (e.g., by evaporation and/or heating), heat-initiated polymerization and/or crosslinking, radiation-initiated polymerization and/or crosslinking, and/or mixing one or more components to initiate polymerization and/or crosslinking. "hardened" refers to a material or composition that has been cured (e.g., polymerized or crosslinked).

By "dental product" is meant an article that can be adhered (e.g., bonded) to an oral surface (e.g., a tooth structure). Typically, the dental product is a prosthetic dentition or a part thereof. Examples include restoratives, replacement teeth, inlays, onlays, veneers, full and partial crowns, bridges, implants, implant abutments, crowns, anterior restoratives, posterior restoratives, cavity liners, sealants, dentitions, stumps, bridge frameworks and other bridge structures, abutments, orthodontic appliances and devices, and dentures (e.g., partial or full dentitions).

As used herein, "sizing" is defined as applying starch, oil, wax, or other suitable ingredients (e.g., organic ingredients) to the fiber bundle to protect and aid in handling. The sizing contains ingredients that provide lubricity and binding. Sizing may also encompass surface treatments such as with silanes, where the silanes may include reactive groups, such as polymerizable groups.

By "oral surface" is meant a soft or hard surface in the oral environment. Hard surfaces typically include dental structures including, for example, natural and artificial tooth surfaces, bone, tooth models, dentin, enamel, cementum, and the like.

By "filler" is meant a particulate material suitable for use in the oral environment. Dental fillers typically have a number average particle size diameter of up to 100 microns.

By "contouring" is meant shaping (using a dental instrument) the material such that the material resembles the process of a natural dental anatomy. For ease of contouring, the material should have a viscosity that is high enough that the material retains its shape after manipulation with a dental instrument, yet the viscosity should not be so high as to make it difficult to shape the material.

By "feathering" is meant the process of reducing the dental restorative material into a film in order to blend the material into the natural dentition. This is achieved with dental instruments at the edges of the material and natural dentition being manipulated.

As used herein, a "nanoparticle" is a discrete non-fumed metal oxide nanoparticle. Discrete non-fumed metal oxide nanoparticles can be further classified as "discrete non-fumed non-heavy metal oxide nanoparticles" or "discrete non-fumed heavy metal oxide nanoparticles. By "discrete non-pyrogenic non-heavy metal oxide nanoparticles" is meant an oxide of an element other than a heavy metal (which is defined herein as "discrete non-pyrogenic heavy metal oxide nanoparticles"). As used herein, "non-heavy metal oxide" means a metal oxide of an element having an atomic number no greater than 28. In one aspect of the disclosure, the silica is an example of a non-heavy metal oxide, and the silica nanoparticles are an example of discrete non-fumed non-heavy metal oxide nanoparticles. As used herein, "heavy metal oxide" means an oxide of an element having an atomic number greater than 28. In one aspect of the present disclosure, zirconia is an example of a heavy metal oxide. The average particle size of the nanoparticles may be determined by cutting a thin sample of the hardened dental composition and measuring the particle size of about 50 to 100 particles using a transmission electron micrograph at 300,000 magnification and calculating the average.

As used herein, "discrete" means unaggregated individual particles (e.g., nanoparticles) that are separated from one another.

As used herein, "nanocluster" generally refers to a group of two or more nanoparticles associated by relatively weak but sufficient intermolecular forces that can cause the nanoparticles to clump together, even when dispersed in a hardenable resin. Preferred nanoclusters may include discrete non-fumed non-heavy metal oxide nanoparticles (e.g., silica nanoparticles) and loosely aggregated substantially amorphous clusters of heavy metal oxides (e.g., zirconia). In the case where zirconia is present as a heavy metal oxide, the zirconia may be crystalline or amorphous. In addition, the heavy metal oxide may be present as particles (e.g., discrete non-pyrogenic heavy metal oxide nanoparticles, such as zirconia nanoparticles). The nanocluster forming particles preferably have an average diameter of 5nm to about 100 nm. However, the average particle size of loosely aggregated nanoclusters is typically significantly larger. Typically, the nanoclusters have a longest dimension in the micron range (e.g., 3 microns, 5 microns, 7 microns, 10 microns, and in some cases, 30 to 50 microns). The Size of the nanoclusters may be determined according to the method generally described in us patent 6,730,156(Windisch et al) (column 21, lines 1 to 22, "Cluster Size Determination").

By "substantially amorphous" is meant that the nanoclusters are substantially free of crystalline structures. The absence of Crystallinity (or the presence of an amorphous phase) is preferably determined by a Procedure that provides a Crystallinity Index as generally described in U.S. patent 6,730,156(Windisch et al) (column 21, line 23 through column 22, line 33, "Crystallinity Index Procedure"). The crystallinity index characterizes the extent to which a material is crystalline or amorphous, whereby a value of 1.0 indicates a fully crystalline structure and a value close to zero indicates the presence of only an amorphous phase. The nanoclusters of the present disclosure preferably have an index of less than about 0.1, more preferably less than about 0.05.

By "nano" is meant a form of material having at least one dimension averaging up to 200 nanometers (e.g., discrete non-fumed metal oxide nanoparticles). Thus, nanomaterial refers to a material comprising nanoparticles and nanoclusters, for example, as defined herein. Thus, for example, "nanoparticles" refers to particles having a number average diameter of up to 200 nanometers. As used herein, "size" with respect to spherical particles refers to the diameter of the particles. As used herein, "size" with respect to non-spherical particles refers to the longest dimension of the particle. In certain embodiments, the nanoparticles are comprised of discrete, non-aggregated and non-agglomerated particles.

As used herein, the term "ethylenically unsaturated compound" is intended to include monomers, oligomers, and polymers having at least one ethylenically unsaturated group.

By "polymerizing" is meant forming heavier materials from monomers or oligomers. The polymerization reaction may also involve a crosslinking reaction.

As used herein, the term "(meth) acrylate" is a shorthand form for acrylate, methacrylate, or a combination thereof, and "(meth) acrylic" is a shorthand form for acrylic, methacrylic, or a combination thereof. As used herein, a "(meth) acrylate functional compound" is a compound that includes, among other things, a (meth) acrylate moiety.

As used herein, a "hardened composite" is a composite of the present disclosure that undergoes a physical and/or chemical transformation to make a strong and compact composite that is pressure resistant. The composite material may be physically and/or chemically transformed by a setting, curing, polymerization, crosslinking, or melting process.

As used herein, "translucency" is the degree to which a material transmits light. This can be quantified by the contrast ratio, translucency parameter, or percent transmittance of a material of known thickness. The translucency of dental restorative materials is often determined by the contrast ratio. The contrast ratio is set on a standardized black backgroundWhite light re-emittance (R) of the sample in (1)_b) White light re-emittance (R) with samples placed in a standardized white background_w) The ratio of (a) to (b). Contrast ratio according to CR ═ R_b/R_wX 100 was calculated. A contrast ratio of 100 indicates that the sample is completely opaque. The translucency is indicated as 100-CR.

As used herein, a "dental mill blank" is a block of material (e.g., hardened composite material) that can be milled into a dental product.

By "machining" is meant milling, grinding, cutting, engraving or shaping, etc., of a material having a three-dimensional structure or shape by a machine.

As used herein, "CAD/CAM" is an abbreviation for computer-aided design (CAD-aided design)/computer-aided manufacturing (CAD-aided manufacturing).

In the present disclosure, reference is made to weight percent (wt%) values of the various components (e.g., at least the polymerizable component, the ceramic fibers, and the nanoclusters) that make up the composite. These wt% values for the composite are based on the total weight of the composite, and the wt% values for all components used to form the composites of the present disclosure always sum to a value of 100 wt%.

The words "preferred" and "preferably" refer to embodiments of the disclosure that may provide certain benefits under certain circumstances. However, other embodiments may also be preferred, under the same or other circumstances. Furthermore, the recitation of one or more preferred embodiments does not imply that other embodiments are not useful, and is not intended to exclude other embodiments from the scope of the disclosure.

In this application, terms such as "a," "an," and "the" are not intended to refer to only a single entity, but include the general class of which a specific example may be used for illustration. The terms "a", "an" and "the" are used interchangeably with the term "at least one". The phrases "at least one (kind) in … …" and "at least one (kind) comprising … …" in the following list refer to any one of the items in the list and any combination of two or more of the items in the list.

As used herein, the term "or" is generally employed in its ordinary sense, including "and/or" unless the context clearly dictates otherwise.

The term "and/or" means one or all of the listed elements or a combination of any two or more of the listed elements.

Likewise, all numerical values herein are assumed to be modified by the term "about" and preferably by the term "exactly. As used herein, with respect to a measured quantity, the term "about" refers to a deviation in the measured quantity that is commensurate with the objective of the measurement and the accuracy of the measurement equipment used, as would be expected by a skilled artisan taking the measurement with some degree of care. Also herein, the recitations of numerical ranges by endpoints include all numbers subsumed within that range and the endpoints (e.g., 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4,5, etc.).

As used herein, as a modifier to a property or attribute, unless specifically defined otherwise, the term "substantially" means that the property or attribute will be readily identifiable by a person of ordinary skill without requiring an absolute precision or perfect match (e.g., within +/-20% for quantifiable properties). Unless specifically defined otherwise, the term "substantially" means a high degree of approximation (e.g., within +/-10% for quantifiable characteristics), but again does not require absolute precision or a perfect match. Terms such as identical, equal, uniform, constant, strict, etc., are to be understood as being within ordinary tolerances, or within measurement error applicable to the particular situation, rather than requiring an absolutely exact or perfect match.

In a first aspect, a composite material is provided. The composite material comprises: 20 to 40 weight percent (wt.%) of a polymerizable component; 6 to 40 wt% of ceramic fibers; and 30 to 70 wt% nanoclusters. The wt% values of the composite are based on the total weight of the composite and add up to values of 100 wt%. Each of the ceramic fibers has a diameter and a length, the ceramic fibers have an arithmetic mean diameter of 0.3 to 5 microns, and fifty percent of the ceramic fibers have a length of at least 10 microns based on the total number of ceramic fibers, and ninety percent of the ceramic fibers have a length of no greater than 500 microns based on the total number of ceramic fibers.

It has been found that the incorporation of ceramic fibers having a range of diameters enhances the strength of the hardened composite material according to the present disclosure, as well as providing good polish retention and visual appearance. More specifically, the ceramic fibers have an arithmetic mean diameter (i.e., the sum of the diameters of a group of fibers divided by the number of fibers in the group) of 0.3 to 5 microns, such as 0.3 to 3 microns or 2 to 5 microns. For example, the ceramic fibers may have an arithmetic mean diameter as follows: 0.3 microns or greater, 0.4 microns or greater, 0.5 microns or greater, 0.6 microns or greater, 0.7 microns or greater, 0.8 microns or greater, 0.9 microns or greater, 1.0 microns or greater, 1.25 microns or greater, 1.5 microns or greater, 1.75 microns or greater, 2.0 microns or greater, 2.25 microns or greater, 2.5 microns or greater, or 2.75 microns or greater; and 5.0 microns or less, 4.75 microns or less, 4.5 microns or less, 4.25 microns or less, 4.0 microns or less, 3.75 microns or less, 3.5 microns or less, 3.25 microns or less, or 3.0 microns or less. The diameter is measured using a Scanning Electron Microscope (SEM), in which the diameter of at least 50 (e.g., 50 to 100) individual ceramic fibers is measured, and the arithmetic mean is calculated from all the measured diameters. It will be appreciated that different cross-sectional shapes are possible in addition to the circular cross-section of the ceramic fiber. Examples include, but are not limited to, ribbon, oval (non-circular), and polygonal (e.g., triangular or square), as well as other shapes known in the art.

The ceramic fibers of the composite material also each have a length. Since each of the ceramic fibers may have a different length, the lengths of the ceramic fibers may be grouped as a percentage of the total number of ceramic fibers above or below a given length value. For example, the ceramic fiber length "L" is given by the fraction of ceramic fibers that is shorter or longer than a given value. Thus, for example, "L50" may indicate that 50% of the ceramic fibers are less than or equal to the L50 length value, and that 50% of the ceramic fibers are greater than the L50 length value (this is also referred to as the median length), and that L90 may indicate that 90% of the ceramic fibers are less than or equal to the L90 length value.

In some embodiments, fifty percent of the length in the ceramic fibers (i.e., "L50") is at least 10 microns based on the total number of ceramic fibers, and ninety percent (%) of the length in the ceramic fibers (i.e., "L90") is no greater than 500 microns based on the total number of ceramic fibers. The L90 values (90% of the length in the ceramic fibers based on the total number of ceramic fibers) may also include any of the following values: 400 microns or less, 300 microns or less, 200 microns or less, or 100 microns or less; while the L50 value (50% of the length in the ceramic fibers based on the total number of ceramic fibers) may also include any of the following values: 15 microns or greater, 20 microns or greater, 25 microns or greater, 30 microns or greater, 35 microns or greater, or 40 microns or greater, where combinations of ranges of values for L90 and L50 are possible.

The ceramic fibers of the present disclosure may also have an arithmetic mean length. For example, the ceramic fibers of the composite material may have an arithmetic mean length of 50 microns to less than 500 microns. Preferably, the ceramic fibers of the composite material may have an arithmetic mean length of 50 to 250 microns.

The size and shape of the ceramic fibers of the composite material may also be described based on their aspect ratio (e.g., ratio of length to diameter). It should be understood that the cross-sectional shape of the ceramic fiber may not be exactly circular. Thus, the cross-sectional area of the ceramic fiber can be used to derive a "diameter" value to be used for the aspect ratio discussed herein. For the purposes of this disclosure, the aspect ratio of the arithmetic mean length of the ceramic fibers to the arithmetic mean diameter of the ceramic fibers is at least 5:1 (mean length: mean diameter), at least 10:1, at least 15:1, at least 20:1, at least 25:1, at least 30:1, at least 40:1, at least 50:1, at least 65:1, at least 75:1, at least 90:1, at least 100:1, at least 125:1, or at least 150: 1; and 200:1 or less (average length: average diameter), 180:1 or less, 160:1 or less, 140:1 or less, 120:1 or less, 100:1 or less, 80:1 or less, or 60:1 or less.

Without being bound by theory, it is hypothesized that using ceramic fibers having diameters in the range of 0.3 microns to 5 microns provides two advantages. First, the small diameter of the fibers means that the length to diameter ratio (L/D) can be large, even for fibers that are chopped to short lengths. For example, a 1 micron diameter fiber that is 100 microns long will have an L/D of 100:1, while a 10 micron diameter fiber of the same length will only have an L/D of 10. In dental restorations, a short length is important because of the small size of the composite (a few millimeters or less). Small diameter fibers enable long L/D ratios to be achieved even in very small samples. Second, in the radial tensile strength (DTS) test, the fibers are aligned transverse to the loading direction because the DTS test disk is cut from a long tube into which the fiber-containing resin is extruded. The extrusion process aligns the fibers parallel to the tube axis, which is transverse to the DTS test loading direction. FIG. 1 is, for example, an SEM micrograph of the DTS fractured surface of a hardened composite (of example 4) comprising MICROSTRAND 110X fibers 12 having a measured average diameter of 2.05 microns. Fig. 1 shows that the hardened matrix material 12 contains fibers 14 that are highly aligned perpendicular to the fracture surface.

Fig. 2 is a (higher resolution) SEM micrograph of a hardened composite (of comparative example B) comprising fibers having an 50/50 mixture of alumina and silica, with a reported diameter of about 15 microns. Fig. 2 shows that the fiber surface 24 is very clean, i.e., has no residual matrix material 22 bonded thereto. This indicates that the fiber matrix bonding is very weak. Thus, the ceramic fibers do not act as strength enhancing reinforcement in the DTS test, but are more accurately described as brittle strength limiting inclusions. In at least certain embodiments according to the present disclosure, the small diameter fibers provide good fiber matrix bonding. Figure 3 shows the DTS fracture surface of a hardened composite (of example 3) comprising microsoft nd 106 borosilicate glass fibers having a measured mean diameter of 0.35 microns. The matrix material 32 is shown in fig. 3 as being bonded to a majority of the fiber surface 34, and the strong fiber matrix bond contributes to high transverse strength in the fiber reinforced composite. The DTS test measures the strength of the composite transverse to the primary fiber orientation. The smaller the fiber diameter, the smaller the strength limiting inclusions. In other words, the cross-direction loading in the DTS test can be more easily distributed around the smaller fibers.

The ceramic fibers of the present disclosure can have a variety of compositions. Preferably, the ceramic fibers of the present disclosure are at least partially amorphous ceramic fibers or fully amorphous ceramic fibers. The ceramic fibers may be produced in continuous lengths, as described herein, which are chopped or sheared to provide the ceramic fibers of the present disclosure.

In some embodiments, the ceramic fibers comprise alumina fibers, alumina-silica fibers, alumino-borosilicate fibers, zirconia-silica fibers, borosilicate glass fibers, silicate fibers modified with alkali or alkaline earth metals, fused silica fibers, leached silica fibers, quartz fibers, glass fibers, or combinations thereof. In selected embodiments, preferred ceramic fibers are comprised of alumina-silica fibers, borosilicate glass fibers, or combinations thereof.

The ceramic fibers of the present disclosure can be made from a variety of commercially available ceramic filaments. Examples of filaments that may be used to form the CERAMIC FIBERs of the present disclosure include alumina-silica FIBERs sold under the tradenames "SAFFIL LDM" and "SAFFIL 3D + FIBER" by Unifrax LLC of waterfall, nicagara Falls, NY under the tradename "FIBERFRAX CERAMIC FIBER bun 7000", by Cole-Parmer, Vernon Hills, il. Another suitable alumina-silica fiber is similar to example 1 of U.S. patent 4,047,965(Karst et al). Ceramic fibers according to the present disclosure may also be formed from other suitable ceramic filaments, including glass fibers sold by Johnmann Phillips, Johns Manville, Waterville, OH under the tradenames "JM MICRO-STRAND 106-" and "JM MICRO-STRAND 110X-481" of Wattveld, Ohio.

As described herein, the ceramic fibers of the present disclosure may be cut or chopped so as to provide a fiber length percentage within the ranges described herein. Producing ceramic fibers having this length range may be accomplished by cutting continuous filaments of ceramic material in a mechanical shearing operation or a laser cutting operation, as well as other cutting operations.

The composite material may comprise 6 to 40 wt% of ceramic fibers, based on the total weight of the composite material. For example, the composite material can comprise 6 wt% or more, 7 wt% or more, 8 wt% or more, 9 wt% or more, 10 wt% or more, 12 wt% or more, 14 wt% or more, 16 wt% or more, 18 wt% or more, based on the total weight of the composite material; and 40 wt% or less, 37 wt% or less, 35 wt% or less, 32 wt% or less, 27 wt% or less, 25 wt% or less, 22 wt% or less, or 20 wt% or less of ceramic fibers. In other words, the composite material may comprise 6 to 40, 6 to 30, or 10 to 20 weight percent ceramic fibers, based on the total weight of the composite material. As described herein, for a given combination of components forming a composite, the weight% of each of the components adds up to 100 weight% (weight% based on the total weight of the composite).

Some suitable ceramic fibers are commercially available, which are pretreated with an organic sizing or finish that serves as an aid in textile processing. Sizing may include the use of starch, oil, wax, or other organic ingredients applied to the filament bundle to protect and aid in handling. Sizing may also include a surface treatment such as with silane, where the surface treatment may or may not include polymerizable groups. The sizing can be removed from the ceramic filaments by heat treating the filaments or ceramic fibers at a temperature of 700 ℃ for one to four hours.

One or more (e.g., two or more) coupling agents may also be used with the ceramic fibers, either as they are received or after they are treated to remove any sizing and/or increase their surface area. One or more coupling agents may also be used with the filler particles, as described herein. Thus, a combination of two or more coupling agents as described herein may be used in a composite material with the ceramic fibers and filler particles (when present). In some embodiments, such coupling agents may help provide chemical bonds (e.g., covalent bonds) between the polymerizable component and the ceramic fibers and filler particles (when present). The coupling agent is a compound that is capable of reacting with both the polymerizable component and the ceramic fibers and filler particles (when present), thereby acting as a joint between the polymerized polymerizable component and the ceramic fibers and filler particles (when present). The ceramic fibers and filler particles (when present) can be treated with a coupling agent prior to mixing with the polymerizable component. Thus, in some embodiments, the coupling agent comprises a polymerizable group, such as, for example, one or more epoxy groups, acrylate groups, and/or (meth) acrylate groups. In other embodiments, the coupling agent does not comprise a polymerizable group.

In some embodiments, the coupling agent may be selected from an organosilane coupling agent, a titanate coupling agent, a zirconate coupling agent, an acidic coupling agent, or combinations thereof. The coupling agent may be applied as a pretreatment to the inorganic material (e.g., ceramic fibers and filler particles, when present) and/or added to the polymerizable component.

The organosilane coupling agent has the general formula R_nSiX_(4-n). A functional group "X" participates in a reaction with a substrate, where X is independently at each occurrence a hydrolyzable group such as an alkoxy, acyloxy, or amine. R is a non-hydrolyzable organic group having a functional group that enables the organosilane coupling agent to bond to or improve compatibility with an organic polymer or the like. Suitable examples of organosilane coupling agents include gamma-methacryloxypropyltrimethoxysilane, gamma-methacryloxyoctyltrimethoxysilane, gamma-mercaptopropyltrimethoxysilane, gamma-aminopropyltrimethoxysilane, beta- (3, 4-epoxycyclohexyl) ethyltrimethoxysilane, gamma-glycidoxypropyltrimethoxysilane, and the like. Other suitable examples of organosilane coupling agents include n-octyltrimethoxysilane, phenyltrimethoxysilane, and the like. Mixtures of organosilane coupling agents may be used.

Titanate coupling agents include a series of monoalkoxy titanates that can function in conjunction with the ceramic fibers and filler particles (when present). The titanate coupling agent typically has three pendant organofunctional groups. The titanate coupling agent also acts as a plasticizer to allow higher loading and/or achieve better flow. Suitable examples of titanate coupling agents include methoxy diethylene glycol trimethacrylic acid titanate.

The zirconate coupling agent comprises 2, 2-bis (allyloxymethyl) butyl trimethacrylzirconate.

The acidic coupling agent comprises mono-2- (methacryloyloxy) ethyl succinate.

The composite materials of the present disclosure are hardenable due to the presence of the polymerizable component. The composite material typically comprises 20 to 40 wt% of the polymerizable component. In some embodiments, the composite material may be hardened (e.g., polymerized by conventional photopolymerization and/or chemical polymerization techniques) prior to application to the oral surface. In other embodiments, the composite material may be hardened (e.g., polymerized by conventional photopolymerization and/or chemical polymerization techniques) after the composite material has been applied to the oral surface.

Examples of polymerizable components include, but are not limited to, those that have sufficient strength, hydrolytic stability, and no toxicity to make them suitable for use in the oral environment. Examples of such materials include acrylates, methacrylates, polyurethanes, carbamyl isocyanates, and epoxies (e.g., those shown in U.S. Pat. No. 3,066,112(Bowen), U.S. Pat. No. 3,539,533(Lee II et al), U.S. Pat. No. 3,629,187(Waller), U.S. Pat. No. 3,709,866(Waller), U.S. Pat. No. 3,751,399(Lee et al), U.S. Pat. No. 3,766,132(Lee et al), U.S. Pat. No. 3,860,556(Taylor), U.S. Pat. No. 4,002,669(Gross et al), U.S. Pat. No. 4,115,346(Gross et al), U.S. Pat. No. 4,259,117(Yamauchi et al), U.S. Pat. No. 4,292,029(Craig et al), U.S. Pat. No. 4,308,190 (Walkowiiak et al), U.S. Pat. No. 4,327,014(Kawahara et al), U.S. Pat. 4,379,695(Orlowski et al), U.S. Pat. 4,387,240 (Berg.

In certain embodiments, the polymerizable component of the composite is photopolymerizable, i.e., the polymerizable component contains a photoinitiator system that initiates polymerization (or hardening) of the composite upon irradiation with actinic radiation. In other embodiments, the polymerizable component of the composite material is chemically hardenable, i.e., the polymerizable component comprises a chemical initiator (i.e., initiator system) that can polymerize, cure, or otherwise harden the composite material without relying on irradiation with actinic radiation. Such chemically hardenable compositions are sometimes referred to as "self-curing" compositions.

The polymerizable component typically comprises one or more ethylenically unsaturated compounds with or without acid functionality. Examples of useful ethylenically unsaturated compounds include acrylates, methacrylates, hydroxy-functional acrylates, hydroxy-functional methacrylates, and combinations thereof.

The composite material, particularly in photopolymerizable embodiments, may comprise compounds having free-radically reactive functional groups, which may include monomers, oligomers, and polymers having one or more ethylenically unsaturated groups. Suitable compounds contain at least one ethylenically unsaturated bond and are capable of undergoing addition polymerization. Such radically polymerizable compounds include: mono-, di-or poly (meth) acrylates (i.e., acrylates and methacrylates) such as methyl (meth) acrylate, ethyl acrylate, isopropyl methacrylate, n-hexyl acrylate, stearyl acrylate, allyl acrylate, glycerol triacrylate, ethylene glycol diacrylate, diethylene glycol diacrylate, triethylene glycol dimethacrylate, 1, 3-propanediol di (meth) acrylate, trimethylolpropane triacrylate, 1,2, 4-butanetriol trimethacrylate, 1, 4-cyclohexanediol diacrylate, pentaerythritol tetra (meth) acrylate, sorbitol hexaacrylate, tetrahydrofurfuryl (meth) acrylate, bis [1- (2-acryloyloxy) ] -p-ethoxyphenyl dimethyl methane, bis [1- (3-acryloyloxy-2-hydroxy) ] -p-propoxyphenyl dimethyl methane Methane, ethoxylated bisphenol a di (meth) acrylate and trimethylol isocyanurate trimethacrylate; (meth) acrylamides (i.e., acrylamide and methacrylamide) such as (meth) acrylamide, methylenebis (meth) acrylamide, and acetylacetone (meth) acrylamide; urethane (meth) acrylate; bis (meth) acrylates of polyethylene glycol (preferably having a molecular weight of 200 to 500), copolymerizable mixtures of acrylated monomers (such as those in U.S. Pat. No. 4,652,274(Boettcher et al)), acrylated oligomers (such as those in U.S. Pat. No. 4,642,126(Zador et al)), and poly (ethylenically unsaturated) carbamoyl isocyanurates (such as those disclosed in U.S. Pat. No. 4,648,843 (Mitra)); and vinyl compounds such as styrene, diallyl phthalate, divinyl succinate, divinyl adipate, and divinyl phthalate. Other suitable free radically polymerizable compounds include silicone-functionalized (meth) acrylates as disclosed, for example, in WO-00/38619(Guggenberger et al), WO-01/92271(Weinmann et al), WO-01/07444(Guggenberger et al), WO-00/42092(Guggenberger et al), and fluoropolymer-functionalized (meth) acrylates as disclosed, for example, in U.S. Pat. No. 5,076,844(Fock et al), U.S. Pat. No. 4,356,296(Griffith et al), EP-0373384(Wagenknecht et al), EP-0201031 (Reiners et al), and EP-0201778 (Reiners et al). Mixtures of two or more free-radically polymerizable compounds can be used, as desired. In some embodiments, a methacryl-containing compound may be used.

The polymerizable component may also contain hydroxyl groups and ethylenically unsaturated groups in a single molecule. Examples of such materials include hydroxyalkyl (meth) acrylates such as 2-hydroxyethyl (meth) acrylate and 2-hydroxypropyl (meth) acrylate; glycerol mono (meth) acrylate or glycerol di (meth) acrylate; trimethylolpropane mono (meth) acrylate or trimethylolpropane di (meth) acrylate; pentaerythritol mono (meth) acrylate, pentaerythritol di (meth) acrylate and pentaerythritol tri (meth) acrylate; sorbitol mono (meth) acrylate, sorbitol di (meth) acrylate, sorbitol tri (meth) acrylate, sorbitol tetra (meth) acrylate or sorbitol penta (meth) acrylate; and 2, 2-bis [4- (2-hydroxy-3-methacryloxypropoxy) phenyl ] propane (bisGMA). Suitable ethylenically unsaturated compounds are also available from a variety of commercial sources, such as Sigma Aldrich, st. Mixtures of ethylenically unsaturated compounds can be used if desired.

In certain embodiments, the polymerizable component comprises a compound selected from the group consisting of: dimethacrylates of polyethylene glycol having a weight average molecular weight of 200 to 1000, such as PEGDMA (polyethylene glycol dimethacrylate having a molecular weight of about 400), UDMA (urethane dimethacrylate), GDMA (glycerol dimethacrylate), TEGDMA (triethylene glycol dimethacrylate), 2 to 10 moles of ethoxylated bisphenol-a dimethacrylate (Bis-EMA) such as bisEMA6 described in U.S. Pat. No. 6,030,606(Holmes), NPGDMA (neopentyl glycol dimethacrylate), glycerol dimethacrylate, 1, 3-propanediol dimethacrylate, and 2-hydroxyethyl methacrylate. Various combinations of these hardenable components may be used. For certain embodiments, including any of the embodiments above, the polymerizable resin comprises a compound selected from the group consisting of: 2, 2-bis [4- (2-hydroxy-3-methacryloxypropoxy) phenyl ] propane (bisGMA), triethylene glycol dimethacrylate (TEGDMA), polyurethane dimethacrylate (UDMA), 2 to 10 moles of ethoxylated bisphenol-a dimethacrylate (bisEMA), dimethacrylate of polyethylene glycol having a weight average molecular weight of 200 to 1000, glycerol dimethacrylate, 1, 3-propanediol dimethacrylate, and combinations thereof.

When the composite material comprises ethylenically unsaturated compounds having no acid functionality, the ethylenically unsaturated compounds having no acid functionality are typically present in an amount of at least 5 weight percent, more typically at least 10 weight percent, and most typically at least 15 weight percent, based on the total weight of the unfilled composition. The compositions of the present disclosure typically comprise up to 95 weight percent, more typically up to 90 weight percent, and most typically up to 80 weight percent of ethylenically unsaturated compounds having no acid functionality, based on the total weight of the unfilled composition.

In some embodiments, the polymerizable component may comprise one or more ethylenically unsaturated compounds having acid functionality. As used herein, ethylenically unsaturated compounds "having acid functionality" are intended to include monomers, oligomers, and polymers having ethylenically unsaturated groups as well as acid and/or acid precursor functionality. Acid precursor functional groups include, for example, acid anhydrides, acid halides, and pyrophosphates. The acidic functional groups may include carboxylic acid functional groups, phosphoric acid functional groups, phosphonic acid functional groups, sulfonic acid functional groups, or combinations thereof.

Ethylenically unsaturated compounds having an acid functional group include, for example, α, β -unsaturated acidic compounds such as glycerophosphoric acid mono (meth) acrylate, glycerophosphoric acid di (meth) acrylate, hydroxyethyl (meth) acrylate (e.g., HEMA) phosphoric acid, bis ((meth) acryloyloxyethyl) phosphoric acid, ((meth) acryloyloxypropyl) phosphoric acid, bis ((meth) acryloyloxy) propoxy phosphoric acid, (meth) acryloyloxyhexyl phosphoric acid, bis ((meth) acryloyloxyhexyl) phosphoric acid, (meth) acryloyloxyoctyl phosphoric acid, bis ((meth) acryloyloxyoctyl) phosphoric acid, (meth) acryloyloxydecyl phosphoric acid, bis ((meth) acryloyloxydecyl) phosphoric acid, phosphocaprolactone acrylate, citric acid di-or tri-methacrylate, di-or tri-methacrylate, Poly (meth) acrylated oligomaleic acid, poly (meth) acrylated polymaleic acid, poly (meth) acrylated poly (meth) acrylic acid, poly (meth) acrylated polycarboxy-polyphosphonic acid, poly (meth) acrylated polychlorophosphoric acid, poly (meth) acrylated polysulfonic acid, poly (meth) acrylated polyboric acid, and the like, can be used as components in the hardenable component system. Monomers, oligomers, and polymers of unsaturated carbonic acids such as (meth) acrylic acid, aromatic (meth) acrylate acids (e.g., methacrylated trimellitic acid), and their anhydrides may also be used. Certain preferred compositions of the present disclosure include ethylenically unsaturated compounds having acid functionality with at least one P-OH moiety.

When the composition comprises ethylenically unsaturated compounds with acid functionality, the ethylenically unsaturated compounds with acid functionality are typically present in an amount of at least 1 weight percent, more typically at least 3 weight percent, and most typically at least 5 weight percent, based on the total weight of the unfilled composition. The compositions of the present disclosure typically comprise up to 80 weight percent, more typically up to 70 weight percent, and most typically up to 60 weight percent of ethylenically unsaturated compounds with acid functionality, based on the total weight of the unfilled composition.

For free radical polymerization (hardening), the initiator system may be chosen from systems which initiate polymerization by radiation, heat or redox/self-curing chemical reactions. The class of initiators capable of initiating polymerization of free radically active functional groups includes free radical generating photoinitiators, optionally in combination with photosensitizers or accelerators. Such initiators are generally capable of generating free radicals for addition polymerization when exposed to light energy having a wavelength between 200nm and 800 nm.

In certain embodiments, one or more heat-activated initiators are used to thermally harden the polymerizable components. Examples of thermal initiators include peroxides and azo compounds, such as benzoyl peroxide, lauryl peroxide, 2-Azobisisobutyronitrile (AIBN).

In certain embodiments, the thermally activated initiator is selected such that no measurable amount of free radical initiating species is produced at temperatures below about 100 ℃. By "measurable amount" is meant an amount sufficient to cause polymerization and/or crosslinking to the extent that an observable change in the properties of the composition (e.g., viscosity, moldability, hardness, etc.) occurs. For certain embodiments, the initiator is activated at a temperature in the range of 120 ℃ to 140 ℃, or in some embodiments, in the range of 130 ℃ to 135 ℃. For certain of these embodiments, the initiator is an organic peroxide that can be thermally activated in any of these temperature ranges to produce a measurable amount of free radical initiating species. For certain of these embodiments, the initiator is selected from the group consisting of dicumyl peroxide, t-butyl peroxide, and combinations thereof. For certain of these embodiments, the initiator is dicumyl peroxide. In other embodiments, the initiator is selected from the group consisting of 2, 5-bis (t-butylperoxy) -2, 5-dimethylhexane, 2, 5-bis (t-butylperoxy) -2, 5-dimethyl-3-hexyne, bis (1- (t-butylperoxy) -1-methylethyl) benzene, t-butyl peracetate, t-butyl peroxybenzoate, cumene hydroperoxide, 2, 4-pentanedione peroxide, peracetic acid, and combinations thereof.

For certain embodiments, the thermally activated initiator is present in the composition in an amount of at least 0.2% based on the weight of the polymerizable components. For certain of these embodiments, the initiator is present in an amount of at least 0.5%. For certain of these embodiments, the initiator is present in the composition in an amount of no more than 3% by weight based on the weight of the polymerizable components. For certain of these embodiments, the initiator is present in an amount of no more than 2%.

In certain embodiments, the composition may additionally be photopolymerizable, i.e., the composition comprises a photoinitiator system that initiates polymerization (curing or hardening) of the composition upon irradiation with actinic radiation. Suitable photoinitiators (i.e., photoinitiator systems comprising one or more compounds) for polymerizing free-radical photopolymerizable components include binary systems and ternary systems. A typical ternary photoinitiator comprises an iodonium salt, a photosensitizer, and an electron donor compound, as described in U.S. Pat. No. 5,545,676(Palazzotto et al). Suitable iodonium salts are diaryliodonium salts, such as diphenyliodonium chloride, diphenyliodonium hexafluorophosphate, diphenyliodonium tetrafluoroborate and tolylcumylium tetrakis (pentafluorophenyl) borate. Suitable photosensitizers are mono-and di-ketones which absorb some light in the range 400nm to 520nm, preferably 450nm to 500 nm. Particularly suitable compounds include alpha diketones having light absorption in the range of 400 nanometers to 520 nanometers, and even more preferably 450 nanometers to 500 nanometers. Suitable compounds are camphorquinone, benzil, furilyl, 3,6, 6-tetramethylcyclohexanedione, phenanthrenequinone, 1-phenyl-1, 2-propanedione and also other 1-aryl-2-alkyl-1, 2-ethanediones and cyclic alpha-diketones. Suitable electron donor compounds include substituted amines, such as ethyl dimethylaminobenzoate. Other suitable ternary photoinitiator systems that can be used to photopolymerize cationically polymerizable resins are described, for example, in U.S. Pat. No. 6,765,036(Dede et al).

Other useful photoinitiators for polymerizing free-radical photopolymerizable components include the class of phosphine oxides, which typically have a functional group wavelength in the range of 380nm to 1200 nm. Preferred phosphine oxide free radical initiators having a functional wavelength in the range of 380nm to 450nm are acylphosphine oxides and bisacylphosphine oxides, as described, for example, in U.S. Pat. Nos. 4,298,738(Lechtken et al), 4,324,744(Lechtken et al), 4,385,109(Lechtken et al), 4,710,523(Lechtken et al) and 4,737,593(Ellrich et al), 6,251,963(Kohler et al); and those described in EP application 0173567 a2 (Ying).

Commercially available phosphine oxide photoinitiators capable of free radical initiation when irradiated in a wavelength range other than 380nm to 450nm include bis (2,4, 6-trimethylbenzoyl) phenylphosphine oxide (OMNIRAD 819, Einsimon corporation of Valweck, Netherlands (IGM Resins, Waalwijk, The Netherlands)), bis (2, 6-dimethoxybenzoyl) - (2,4, 4-trimethylpentyl) phosphine oxide (CGI 403, Ciba Specialty Chemicals), a mixture of 1:1 by weight of bis (2,4, 6-trimethylbenzoyl) phenylphosphine oxide and 2-hydroxy-2-methyl-1-phenylpropan-1-one (DAROCUR 4265, Ciba Specialty Chemicals) and ethyl 2,4, 6-trimethylbenzylphenylphosphinate (CILR 883593, BASF corporation of Charlotte, north carolina (BASF corp., Charlotte, NC)).

The phosphine oxide initiator may be used in the composite in a catalytically effective amount, such as from 0.1 to 5.0 weight percent based on the total weight of the unfilled composition.

The tertiary amine reducing agent may be used in combination with the acylphosphine oxide. Exemplary tertiary amines useful in the present disclosure include ethyl 4- (N, N-dimethylamino) benzoate and ethyl N, N-dimethylamino methacrylate. When present, the amine reducing agent is present in the composite material in an amount of from 0.1 wt% to 5.0 wt%, based on the total weight of the unfilled composition. Useful amounts of other initiators are well known to those skilled in the art.

Polymerizable components made from cationically curable materials suitable for use in the present disclosure may also include epoxy resins. The epoxy resin imparts high toughness to the composite, which is a desirable characteristic of, for example, dental mill blanks. The epoxy resin may optionally be blended with various combinations of polyols, methacrylates, acrylates, or vinyl ethers. Preferred epoxy resins include diglycidyl ethers of bisphenol A (e.g., EPON 828, EPON 825, Shell Chemical Co.), 3, 4-epoxycyclohexylmethyl-3-4-epoxycyclohexanecarboxylate (e.g., UVR-6105, Union Carbide), bisphenol F epoxide (e.g., GY-281, Ciba-Geigy), and polytetrahydrofuran.

As used herein, a "cationically active functional group" is a chemical group that is activated in the presence of an initiator capable of initiating a cationic polymerization reaction so that it can react with other compounds having cationically active functional groups. Materials having cationically active functional groups include cationically polymerizable epoxy resins. Such materials are organic compounds having oxirane rings (i.e., groups) that can be polymerized by ring opening. These materials include monomeric epoxy compounds and polymeric epoxides and may be aliphatic, cycloaliphatic, aromatic or heterocyclic. These materials generally have an average of at least 1 polymerizable epoxy group per molecule (preferably at least about 1.5, and more preferably at least about 2 polymerizable epoxy groups per molecule). Polymeric epoxides include linear polymers having terminal epoxy groups (e.g., diglycidyl ether of polyoxyalkylene glycol), polymers having backbone oxirane units (e.g., polybutadiene polyepoxide), and polymers having pendant epoxy groups (e.g., polymers or copolymers of glycidyl methacrylate). The epoxide may be a pure compound or may be a mixture of compounds containing one, two or more epoxy groups per molecule. The "average" number of epoxy groups per molecule is determined by dividing the total number of epoxy groups in the epoxy-containing material by the total number of epoxy-containing molecules present.

These epoxy-containing materials can vary from low molecular weight monomeric materials to high molecular weight polymers, and can vary greatly in the nature of their backbone and substituents. Examples of permissible substituents include halogens, ester groups, ethers, sulfonate groups, siloxane groups, nitro groups, phosphate groups, and the like. The weight average molecular weight of the epoxy-containing material can vary from about 58 to about 100,000 or more. The molecular weights (e.g., weight average molecular weights) of the present disclosure are measured using size exclusion chromatography and polystyrene standards.

Useful epoxy-containing materials include those containing cyclohexene oxide groups, for example epoxycyclohexanecarboxylate, typically 3, 4-epoxycyclohexylmethyl-3, 4-epoxycyclohexanecarboxylate, 3, 4-epoxy-2-methylcyclohexylmethyl-3, 4-epoxy-2-methylcyclohexanecarboxylate, and bis (3, 4-epoxy-6-methylcyclohexylmethyl) adipate. For a more detailed list of useful epoxides of this nature, reference is made to U.S. Pat. No. 3,117,099(Proops et al), incorporated herein by reference.

Blends of various epoxy-containing materials are also contemplated. Examples of such blends include two or more epoxy-containing compounds of weight average molecular weight distribution, such as low molecular weight (below 200), intermediate molecular weight (about 200 to 10,000), and higher molecular weight (above about 10,000). Alternatively or additionally, the epoxy resin may comprise a blend of epoxy-containing materials having different chemical properties, such as aliphatic and aromatic, or functional groups such as polar and non-polar. Other types of useful materials having cationically active functional groups include vinyl ethers, oxetanes, spiroorthocarbonates, spiroorthoesters, and the like.

For hardening the polymerizable component comprising cationically active functional groups, the initiator system can be selected from systems which initiate the polymerization reaction via radiation, heat or redox/self-curing chemical reactions. For example, epoxy polymerization can be accomplished by using a thermal curing agent (e.g., anhydride or amine). One particularly useful example of an anhydride curing agent would be cis-1, 2-cyclohexanedicarboxylic anhydride.

Alternatively, the initiator system comprising a cationically active functional polymerizable component is a photosensitized system. A wide variety of cationic photosensitive groups recognized in the photocatalyst and photoinitiator fields can be used in the practice of this disclosure. The photosensitive cationic core, the photosensitive cationic moiety, and the photosensitive cationic organic compound are art-recognized classes of materials, such as those exemplified in U.S. Pat. Nos. 4,250,311(Crivello), 3,708,296(Schlesinger), 4,069,055(Crivello), 4,216,288(Crivello), 5,084,586(Farooq), 5,124,417(Farooq), 4,985,340(Palazzotto et al), 5,089,536(Palazzotto), and 5,856,373(Kaisaki et al), each of which is incorporated herein by reference.

The cationic curable materials may be used in combination with the three-component or ternary photoinitiator systems described above. Three-component initiator systems are also described in U.S. Pat. No. 6,025,406(Oxman et al) and U.S. Pat. No. 5,998,549(Milbourn et al), each of which is incorporated herein by reference.

The chemically hardenable composition may comprise a redox cure system comprising a polymerizable component (e.g., an ethylenically unsaturated polymerizable component) and a redox agent (including an oxidizing agent and a reducing agent). The reducing agent and the oxidizing agent should react with each other or otherwise cooperate with each other to generate free radicals capable of initiating polymerization of the polymerizable component (e.g., the ethylenically unsaturated component). This type of curing is a dark reaction, that is, does not depend on the presence of light, and can be carried out in the absence of light. The reducing and oxidizing agents are preferably sufficiently shelf stable and free of undesirable coloring effects so that they can be stored and used in typical dental environments.

Useful reducing agents include: ascorbic acid, ascorbic acid derivatives and metal-complexed ascorbic acid compounds; amines, in particular tertiary amines, such as 4-tert-butyldimethylaniline; aromatic sulfinates such as p-toluenesulfinic acid salt and benzenesulfinic acid salt; thioureas such as 1-ethyl-2-thiourea, tetraethylthiourea, tetramethylthiourea, 1-dibutylthiourea and 1, 3-dibutylthiourea; and mixtures thereof. Other secondary reducing agents may include cobalt (II) chloride, ferrous sulfate, hydrazine, hydroxylamine (depending on the choice of oxidizing agent), salts of dithionite or sulfite anion, and mixtures thereof. Preferably, the reducing agent is an amine.

Suitable oxidizing agents are also familiar to those skilled in the art and include, but are not limited to, persulfuric acid and its salts, such as sodium, potassium, ammonium, cesium and alkylammonium salts. Additional oxidizing agents include peroxides such as benzoyl peroxide, hydroperoxides such as cumyl hydroperoxide, t-butyl hydroperoxide, and amyl hydroperoxide, and transition metal salts such as cobalt (III) chloride and ferric chloride, cerium (IV) sulfate, perboric acid and its salts, permanganic acid and its salts, perphosphoric acid and its salts, and mixtures thereof.

It may be desirable to use more than one oxidizing agent or more than one reducing agent. Small amounts of transition metal compounds may also be added to accelerate the rate of redox cure.

The reducing agent and the oxidizing agent are present in amounts sufficient to allow for a sufficient radical reaction rate. This can be assessed by combining all the ingredients of the composition, except for the optional filler, and observing whether a hardened mass can be obtained.

Typically, if a reducing agent is actually used, the reducing agent is present in an amount of at least 0.01 weight percent, and more typically at least 0.1 weight percent, based on the total weight of the components of the unfilled composition. Typically, the reducing agent is present in an amount of no greater than 10 weight percent, and more typically no greater than 5 weight percent, based on the total weight of the components of the unfilled composition.

Typically, if an oxidizing agent is actually used, the oxidizing agent is present in an amount of at least 0.01 weight percent, and more typically at least 0.10 weight percent, based on the total weight of the components of the unfilled composition. Typically, the oxidizing agent is present in an amount of no greater than 10 weight percent, and more typically no greater than 5 weight percent, based on the total weight of the components of the unfilled composition.

When used as a dental restorative material, the composite material may have various weight percent values of ceramic fibers and/or nanoclusters, depending on the dental application. Thus, for example, if used as a sealant, the composite material of the present disclosure may be filled with ceramic fibers and/or nanoclusters in order to provide a flowable composite. In such embodiments, the viscosity of the composite is sufficiently low that it can penetrate into recesses and crevices on the occlusal surface of the tooth and into erosive areas of the enamel, thereby helping to retain the composite. In applications where high strength or durability is desired (e.g., anterior or posterior restorations, prostheses, crown and bridge cements, artificial crowns, artificial teeth, and dentures), the loading of ceramic fibers and nanoclusters may be tailored to provide a more rigid composite.

The composite material further comprises 30 to 70 wt% of nanoclusters. The composite material may also comprise other value ranges for the nanoclusters. For example, the composite material may further comprise a lower limit of 30, 35, 40, or 45, and an upper limit of 70, 65, 64, 60,55, or 50, by weight percent of the nanoclusters. This allows a variety of possible ranges for the wt% of nanoclusters in the composite. Examples of such ranges include, but are not limited to, 30 to 70 wt% nanoclusters, 35 to 65 wt% nanoclusters, 30 to 60 wt% nanoclusters, 30 to 55 wt% nanoclusters, with a range of 35 to 64 wt% nanoclusters being preferred.

As described herein, for a given combination of components forming a composite, the weight% of each of the components adds up to 100 weight% (weight% based on the total weight of the composite). Preferably, the nanoclusters are silica-zirconia nanoclusters formed of silica nanoparticles and zirconia, the silica nanoparticles and zirconia being associated by relatively weak intermolecular forces that can cause the silica nanoparticles and zirconia to clump together, even when dispersed in the polymerizable component of the present disclosure. The silica nanoparticles and zirconia (the "primary particles" forming the silica-zirconia nanoclusters) may have an average diameter of 1 nanometer (nm) to 200nm, wherein the resulting silica-zirconia nanoclusters may have a longest dimension in the micrometer range (e.g., 10 micrometers) resulting from the association or "nanoclusters" of the silica nanoparticles and zirconia. The primary particles (e.g., silica nanoparticles and zirconia) forming the silica-zirconia nanoclusters may be grouped together in amorphous cluster formation. However, cluster formation of silica nanoparticles and zirconia is not limited to such amorphous cluster formation.

The silica-zirconia nanoclusters may be prepared by mixing together a nanosilica sol and a preformed nano-zirconia particle sol or a solution of a zirconium salt (e.g., acetate or nitrate). The nano zirconia sol is typically composed of crystalline zirconia nanoparticles. The nanosilica sol typically comprises silica particles having an average diameter of from 1nm to 200nm, more typically from 10nm to 100m, even more typically from 15nm to 60nm, most typically from 15nm to about 35nm, with an average particle diameter of about 20nm being particularly suitable for use in the preparation of silica-zirconia nanoclusters.

Zirconia sols typically contain zirconia particles that are small enough not to scatter most visible light, but large enough to refract shorter wavelength blue light to produce an opalescent effect. Zirconia sols having an average particle size of about 3nm to about 30nm are suitable for forming silica-zirconia nanoclusters. Typically, the zirconia particles in the sol have an average particle size of from 5nm to 15nm, more typically from 6nm to 12nm, and most typically from 7nm to 10 nm. When mixed together under acidic conditions where the sol mixture is stable (such as a pH below 2), the preformed zirconia nanoparticles form a structure with the silica nanoparticles upon gelation and drying that provides the desired opalescent properties while maintaining a high level of light transparency of the final composite.

NALCO 1042 silica sol (Ecolab, inc., st. paul, MN)), NALCO 1034A, or other commercially available colloidal silica sol can be used. If a base-stable sol is used, it is usually first subjected to ion exchange to remove sodium, for example using Amberlite IR-120 ion exchange resin, or adjusting the pH with nitric acid. It is generally desirable to adjust the silica pH to less than 1.2, usually from about 0.8 to about 1.0, and then slowly add zirconia thereto to prevent local gelation and agglomeration. The pH of the resulting mixture is typically from about 1.1 to about 1.2. Suitable colloidal silica sols are available from a variety of suppliers and include NALCO (r.g., wako Corporation), scott Corporation (h.c. stark), SNOWTEX (Nissan Chemical America Corporation Houston, TX), Nyacol Nano Technologies, inc., Ashland, MA, and LUDOX (w.r. grace & Company Columbia, MD)). The sol selected should have silica particles dispersed and of the appropriate size specified herein. The silica sol can be treated to provide a highly acidic silica sol (e.g., nitrate stabilized) that can be mixed with the zirconia sol without gelation.

For example, zirconia sols can be obtained using the methods described in U.S. Pat. No. 6,376,590(Kolb et al) or U.S. Pat. No. 7,429,422(Davidson et al), the disclosures of which are incorporated herein by reference. As used herein, the term "zirconia" refers to the multiple stoichiometry of zirconium oxide, most typically ZrO₂And it may also be referred to as zirconium oxide or zirconium dioxide. The zirconia may contain up to 30% by weight of other chemical moieties, e.g. Y₂O₃And an organic material.

The silica-zirconia nanoclusters may be prepared by mixing together a nanosilica sol and a nanozirconia sol and heating the mixture to at least 450 ℃. Typically, the mixture is heated at a temperature of between about 400 ℃ to about 1000 ℃, more typically between about 450 ℃ to about 950 ℃ for 4 to 24 hours to remove water, organic materials and other volatile components, and potentially to weakly agglomerate the particles (not necessary). Alternatively or additionally, the sol mixture may be subjected to different processing steps to remove water and volatiles. The resulting material may be milled or ground and classified to remove large aggregates. The silica-zirconia nanoclusters may then be surface treated with, for example, silane, prior to mixing with the polymerizable component.

In addition to ceramic fibers, the composite materials of the present disclosure may optionally include one or more filler particles. Such filler particles may be selected from one or more of a variety of materials suitable for incorporation in composite materials for dental applications, such as filler particles currently used in dental restorative compositions and the like. The choice of filler particles can affect the properties of the composite material, such as its appearance, radiopacity, and physical and mechanical properties. By adjusting the amount and relative refractive index of the ingredients in the composite, the translucency, opacity or pearlescence of the composite can be altered, thereby partially affecting the appearance. In this manner, the appearance of the composite material can be made to closely approximate the appearance of natural dentition, if desired.

The filler particles may be selected from one or more materials suitable for incorporation in materials used in compositions for medical applications, such as filler particles currently used in dental restorative compositions and the like. The maximum particle size of the filler particles (the largest dimension of the particles, usually the diameter) is typically less than 20 microns, more typically less than 10 microns, and most typically less than 5 microns. The filler particles generally have a number average particle size diameter of no greater than 100nm, and more typically no greater than 75 nm. The filler particles can have a unimodal or multimodal (e.g., bimodal) particle size distribution. The filler particles may be inorganic materials. The filler particles may also be crosslinked organic materials that are insoluble in the polymerizable component, and optionally filled with an inorganic filler. The filler particles should in any case be suitable for use in the mouth. The filler particles can be radiopaque, radiolucent, or non-radiopaque. The filler particles are typically substantially insoluble in water. The filler particles can have a variety of shapes including, but not limited to, equiaxed, spherical, polyhedral, elliptical, biconvex, or whisker-like.

Examples of suitable filler particles are naturally occurring or synthetic materials such as quartz, nitrides (e.g., silicon nitride); glasses containing, for example, Ce, Sb, Sn, Ba, Zn, and Al; colloidal silicon dioxide; feldspar; borosilicate glass; kaolin; talc; titanium dioxide; and zinc glass; low mohs hardness fillers such as those described in U.S. Pat. No. 4,695,251 (Randklev); and submicron silica particles (e.g., fumed silicas such as the "AEROSIL" series "OX 50", "130", "150", and "200" silicas sold by Degussa Akron, OH, Inc. of Akron, Ohio and the "CAB-O-SIL M5" silicas sold by Cabot Corp., Tuscola, Ill., of Tuscola, Illinois, and non-vitreous microparticles of the type described in U.S. Pat. No. 4,503,169 (Randklev.) the silane-treated zirconia-silica (Zr-Si) filler particles are particularly useful in certain embodiments.

Metal filler particles, such as metal filler particles made of pure metals such as those of groups 4,5, 6,7, 8, 11 or 12, aluminum, indium and thallium of group 13, tin and lead of group 14, or alloys thereof, may also be incorporated, with elements from the groups being present in the 2016 month 1 and 8 day version of the IUPAC periodic table of elements. Conventional dental amalgam powders, typically mixtures of silver, tin, copper and zinc, may also optionally be incorporated. The metal filler particles preferably have a number average particle size diameter of from about 1 micron to about 100 microns, more preferably from 1 micron to about 50 microns. Mixtures of these filler particles are also conceivable, as well as combined filler particles made of organic and inorganic materials.

Preferably, the composite material may comprise up to 15 wt% of nanoparticles (when present) as filler particles, based on the total weight of the composite material. For example, the composite material may comprise 2 to 15 wt% or 2 to 12 wt% nanoparticles as filler particles, based on the total weight of the composite material. As defined herein, the nanoparticles are discrete non-fumed metal oxide nanoparticles. As described herein, for a given combination of components forming a composite, the weight% of each of the components adds up to 100 weight% (weight% based on the total weight of the composite). Examples of discrete non-fumed metal oxide nanoparticles include discrete non-fumed heavy metal oxide nanoparticles. Further, the discrete non-fumed metal oxide nanoparticles can include both discrete non-fumed heavy metal oxide nanoparticles and discrete non-fumed non-heavy metal oxide nanoparticles. Examples of discrete non-fumed non-heavy metal oxide nanoparticles include nanosilica, while examples of discrete non-fumed heavy metal oxide nanoparticles include zirconia, yttria, and lanthana particles. Discrete non-pyrogenic heavy metal oxide nanoparticles can be prepared from heavy metal oxide sols, as described according to U.S. patent 6,736,590(Kolb et al) or U.S. patent 7,429,422(Davidson et al). Discrete non-pyrogenic non-heavy metal oxides are commercially available as colloidal silica. Discrete non-fumed silica nanoparticles can be prepared from a dispersion, sol, or solution of at least one precursor. Processes of this nature are described, for example, in U.S. patent 4,503,169(Randklev) and british patent 2291053B (Noritake et al). The discrete non-fumed metal oxide nanoparticles can also be surface treated with, for example, a silane prior to mixing with the polymerizable component.

The discrete non-fumed metal oxide nanoparticles are typically subdivided in a monomodal or multimodal (e.g., bimodal) particle size distribution. The maximum particle size (the largest dimension of the particle, typically the diameter) of the discrete non-fumed metal oxide nanoparticles is typically from 5nm to 200nm, more typically from 5nm to 100nm, and most typically from 5nm to 80 nm.

Other suitable filler particles are disclosed in U.S. Pat. Nos. 6,387,981(Zhang et al), 6,572,693(Wu et al), 6,730,156(Windisch), and 6,899,948(Zhang), 7,022,173(Cummings et al), 6,306,926(Bretscher et al), 7,030,049(Rusin et al), 7,160,528(Rusin), 7,393,882(Wu et al), 6,730,156(Windisch et al), 6,387,981(Zhang et al), 7,090,722(Budd et al), 7,156,911(Kangas et al), 7,361,216(Kolb et al), and International patent publication WO 03/063804(Wu et al), which are incorporated herein by reference. The filler particles described in these references include nanoscale silica particles, nanoscale metal oxide particles, and combinations thereof. Nanofillers are also described in U.S. patent 7,085,063(Craig et al), 7,090,721(Craig et al), and 7,649,029(Kolb et al), and U.S. patent publication 2010/0089286 (skwiercczynski et al), US 2011/0196062(Craig et al), all of which are incorporated herein by reference.

As described herein, to enhance the bond between the filler and the polymerizable component, the surface of the filler particles may optionally be treated with a surface treatment as described herein. In addition, the ceramic fibers and filler particles (when present) can be modified with more than one (e.g., two or more) surface treatment (e.g., coupling agent and/or surface treatment) as discussed herein. For example, the same surface treatment may be used for each of the ceramic fibers, while a different surface treatment may be used for the filler particles (when present). Different surface treatments may also be used for two or more sets of ceramic fibers and filler particles (when present in the composite). For example, the ceramic fibers to be used in the composite material may include a first set of ceramic fibers having a surface treatment that is compositionally different from a second set of ceramic fibers used in the composite material.

As described herein, in order to achieve good aesthetics in a composite material, the optical properties of the components of the composite need to be highly matched. Examples of such optical properties of the components include not only the hue and color of the components, but also the degree to which the refractive index of the filler (e.g., ceramic fiber) matches the refractive index of the hardened polymerizable component. Matching the refractive indices of the components helps to minimize scattering of light as it passes through the material, thereby helping to provide a more translucent material. Thus, for example, the refractive index value of the ceramic fibers of the present disclosure preferably differs from the refractive index of the hardenable polymerizable component by a value in the range of 0.1 or less. More preferably, the difference between the refractive index value of the ceramic fiber of the present disclosure and the refractive index of the hardening polymerizable component is preferably in the range of 0.05 or less. Most preferred is the case where the refractive index value of the ceramic fiber of the present disclosure is preferably in the range of 0.005 or less from the refractive index of the hardening polymerizable component.

Examples of refractive index values for the ceramic fibers include ceramic fibers having refractive index values of 1.40 to 1.65. Preferably, the ceramic fibers have a refractive index value of 1.50 to 1.58. Most preferably, the ceramic fibers have a refractive index value of 1.51 to 1.56. A preferred method for adjusting the refractive index of the ceramic fiber is by varying the ratio of silicon oxide to ceramic metal oxide. The refractive index of the ceramic fiber can be predicted approximately by interpolation based on a comparison of the relative volume percentages of silica and ceramic metal oxide in the starting mixture. When additional fillers are used with the ceramic fibers, their refractive index values may also be matched within the ranges provided herein.

The composite materials of the present disclosure can be prepared by mixing all of the various components using conventional mixing techniques. The resulting composite may optionally comprise additional fillers (in addition to the ceramic fibers and nanoclusters), solvents, water, and/or other additives as described herein. In general, the photopolymerizable composites of the present disclosure are prepared by mixing the components of the composite under "safe light" conditions. When an influence is exerted on this mixture, a suitable inert solvent may be used, if desired. Any solvent that does not undergo a measurable reaction with the components of the composite may be used.

Examples of suitable solvents include alcohols (e.g., propanol, ethanol), ketones (e.g., acetone, methyl ethyl ketone), esters (e.g., ethyl acetate), other non-aqueous solvents (e.g., dimethylformamide, dimethylacetamide, dimethylsulfoxide, 1-methyl-2-pyrrolidone), or mixtures thereof. If desired, the composites of the present disclosure may contain additives such as indicators, dyes (including photobleaching dyes), pigments, inhibitors, accelerators, viscosity modifiers, wetting agents, antioxidants, tartaric acid, chelating agents, buffers, stabilizers, diluents, and other similar ingredients as would be apparent to one skilled in the art. Surfactants, such as nonionic surfactants, cationic surfactants, anionic surfactants, and combinations thereof, may optionally be used in the compositions. Useful surfactants include non-polymerizable surfactants and polymerizable surfactants.

In addition, pharmaceutical agents or other therapeutic substances may also optionally be added to the composite material. Examples include, but are not limited to, fluoride sources, whitening agents, anticaries agents (e.g., xylitol), remineralizing agents (e.g., calcium phosphate compounds and other calcium and phosphate sources), enzymes, breath fresheners, anesthetics, clotting agents, acid neutralizers, chemotherapeutic agents, immune response modifiers, thixotropes, polyols, anti-inflammatory agents, antimicrobial agents, antifungal agents, xerostomia treatments, desensitizers, and the like of the types commonly used in dental restorative materials. Combinations of any of the above additives may also be used. The selection and amount of any one such additive can be selected by one of skill in the art to achieve the desired results without undue experimentation.

The amount and type of each component in the composite can be adjusted before and after polymerization to provide the desired physical and handling characteristics. For example, the polymerization rate, polymerization stability, flowability, compressive strength, tensile strength, and durability of dental restorative materials can be adjusted in part, typically by varying the type and amount of polymerization initiator, as well as the loading and particle size distribution of fillers. Such adjustments are typically made empirically based on previous experience with the composite material. When the composite material is used in dental applications, any tooth surface receiving the composite material may optionally be pretreated with a substrate and/or an adhesive via methods known to those skilled in the art.

The composite material may be provided in a variety of forms, including one-part systems and multi-part systems, such as two-part paste/paste systems. Other forms are possible that employ a multi-part combination (i.e., a combination of two or more parts), wherein each part is in the form of a powder, liquid, gel, or paste. The various components of the composite material may be separated into individual portions in any desired manner; however, in a redox multi-part system, one part typically comprises an oxidising agent and the other part typically comprises a reducing agent, but it is also possible to combine the reducing agent and the oxidising agent in the same part of the system if the components are kept separate, for example by using microencapsulation.

The hardened composite material according to at least certain embodiments of the present disclosure preferably exhibits at least one desired physical property. These physical properties include the following: flexural strength, radial tensile strength (DTS), fracture toughness, polish retention, and abrasion resistance. Preferably, the article exhibits at least two different desired physical properties, more preferably at least three different desired physical properties, even more preferably at least flexural strength, DTS and fracture toughness, and most preferably at least flexural strength, DTS, fracture toughness and polish retention. Typical amounts of these properties are as follows.

In some embodiments, the composite material forms a hardened composite material having a DTS as follows: 65 megapascals (MPa) or greater, 66MPa or greater, 67MPa or greater, 68MPa or greater, 69MPa or greater, 70MPa or greater, 71MPa or greater, 72MPa or greater, 73MPa or greater, 74MPa or greater, 75MPa or greater, 76MPa or greater, 77MPa or greater, or even 78MPa or greater. DTS can be determined using the "radial tensile strength test method" described in detail in the examples below.

In some embodiments, the composite material forms a hardened composite material having a flexural strength as follows: 170MPa or greater, 172MPa or greater, 174MPa or greater, 176MPa or greater, 178MPa or greater, 180MPa or greater, 182MPa or greater, 184MPa or greater, 186MPa or greater, 188MPa or greater, 190MPa or greater, 192MPa or greater, 194MPa or greater, 196MPa or greater, 198MPa or greater, 200MPa or greater, 202MPa or greater, 204MPa or greater, 206MPa or greater, or even 208MPa or greater. Flexural strength can be determined using the "flexural strength test method" described in detail in the examples below.

In some embodiments, the composite material forms a hardened composite material having a fracture toughness of: 2.50 MegaPascal square root meter (MPa m)^1/2) Or more, 2.55MPa · m^1/2Or more, 2.60MPa · m^1/2Or more, 2.65MPa · m^1/2Or more, 2.70MPa · m^1/2Or more, 2.75MPa · m^1/2Or more, 2.80MPa · m^1/2Or more, 2.85 MPa-m^1/2Or more, 2.90MPa · m^1/2Or more, 2.95MPa · m^1/2Or more, 3.00MPa · m^1/2Or more, 3.05MPa · m^1/2Or more, 3.10MPa · m^1/2Or greater, or 3.15MPa · m^1/2Or larger. Fracture toughness can be determined using the "fracture toughness test method" described in detail in the examples below.

In select embodiments, the composite is formed to have a DTS of 65MPa or greater, a flexural strength of 170MPa or greater, and a flexural strength of 2.50 MPa-m^1/2Or greater fracture toughness.

Is advantageously smallThe use of ceramic fibers of diameter and short length helps to achieve the desired polish retention in the hardened composite. In some embodiments, the composite forms a hardened composite having a polish retention of 40 gloss units or greater at 60 ° after 6000 brushing cycles. The polish retention was determined using "gloss retention after toothbrush abrasion test method" described in detail in the examples below. Preferably, a hardened composite according to at least some embodiments of the present disclosure exhibits polish retention of 40 gloss units or greater at 60 ° after 6000 brushing cycles, and incorporates a DTS of 65MPa or greater, a flexural strength of 170MPa or greater, or 2.50 MPa-m^1/2Or greater fracture toughness, and more preferably all three.

In some embodiments, the ratio of the abrasion resistance of the hardened composite formed from the composite to the abrasion resistance of the hardened polymerizable component formed from the control composite is 2.0 or less, 1.9 or less, 1.8 or less, 1.7 or less, 1.6 or less, 1.5 or less, 1.4 or less, 1.3 or less, or even 1.2 or less. The control composite had the same composition as the composite except that no ceramic fibers were included.

In a second aspect, a dental product is provided. The dental product is prepared by hardening a composite material according to the first aspect as detailed above. Hardening of the composite material may be accomplished based on the type of dental product being prepared. For example, the composite material may be hardened using heat, light, microwave, electron beam, melting, or chemical curing as appropriate. Once hardened, the dental product and/or dental mill blank of the present disclosure can be trimmed, if necessary; and optionally, if necessary, mounted on a gripper stub or post. The dental product may be selected from the group consisting of a dental restoration (e.g., a sealant, an inlay, an onlay, or a bridge), a dental adhesive, a dental mill blank, a dental cement, a dental prosthesis, an orthodontic device, an orthodontic adhesive, a dental casting material, an artificial crown, an anterior filling, a posterior filling, and a cavity liner or a dental coating.

The dental mill blank of the present disclosure is a block of material (a three-dimensional article) that can be machined into a dental article. The dental mill blank can be sized to accommodate machining of one or more dental articles. The dental mill blank of the present disclosure may further include a mounting post or mount to secure the blank in a milling machine for milling a dental restoration. The mounting post or mount acts as a handle by which the blank is secured as it undergoes the milling process. Depending on the desired shape of the dental article, examples of equipment for such milling processes may include CAM machines (e.g., CNC machines) controlled by data provided by CAD systems. These devices produce dental prostheses by cutting, milling and grinding the highly simulated shape and morphology of the desired prosthesis faster and with reduced manual labor requirements compared to conventional manual fabrication procedures. By using a CAD/CAM milling device, the prosthesis can be manufactured efficiently and accurately. Other machining processes may include grinding, sanding, controlled evaporation, electric spark milling (EDM), water jet or laser cutting, or other methods of cutting, removing, shaping, or milling material. After milling, some degree of finishing, polishing, and conditioning may be necessary to obtain a custom fit and/or an aesthetic appearance to the oral cavity.

In a third aspect, a method of making a composite material is provided. The method comprises obtaining a plurality of components according to the first aspect as detailed above, and mixing the plurality of components to produce the composite material. The components of the composite material may be mixed and applied clinically using conventional techniques. Initiation of the photopolymerizable composite typically requires a curing lamp. The composite material may be in the form of a composite or restoration that adheres very well to dentin and/or enamel. Optionally, a substrate layer may be used on the dental tissue to which the composite material is applied.

In a fourth aspect, a method of using a composite material is provided. The method comprises the following steps: placing a composite material according to the first aspect detailed above adjacent to or on a tooth surface; changing the shape of the composite material near or on the tooth surface; and hardening the composite material. Altering the shape of the composite material near or on the surface of the tooth may include forming the composite material into a dental product selected from a dental prosthesis, an orthodontic device, a crown, an anterior filling, a posterior filling, or a cavity liner. These steps may be performed sequentially or in a different order. For example, in a preferred embodiment where the dental restorative material is a dental mill blank or prosthesis, the hardening step is typically completed prior to altering the profile of the material. Altering the profile of the material may be accomplished in a variety of ways, including manual manipulation using hand-held instruments, or by machine or computer-assisted means, such as CAD/CAM milling machines in the case of prostheses and dental mill blanks. Optionally, a finishing step may be performed to polish, finish or apply a coating on the dental restorative material.

The components of the composite material may be included in a kit, wherein the contents of the composite material are packaged in at least one container to contain the composite material and enable storage of the components prior to the components being needed. Accordingly, in a fifth aspect, a kit is provided. The kit includes: a composite material according to the first aspect as detailed above; and at least one container for containing the composite material. More than one composite material described herein may be included in a kit. In addition to the composite material of the present disclosure, the kit may further comprise at least one dental component selected from the group consisting of: cements, adhesives, abrasives, polishes, instruments, software, milling machines, CAD/CAM systems, composites, china, stains, burr, impression materials, dental mill blanks, or combinations thereof.

The features and advantages of the present disclosure are further illustrated by the following examples, which are not meant in any way to be limiting of the disclosure. The particular materials and amounts thereof recited in these examples, as well as other conditions and details, should not be construed to unduly limit this invention. Unless otherwise indicated, all parts and percentages are by weight, all water is deionized water, and all molecular weights are weight average molecular weights.

Selected embodiments of the disclosure

Embodiment 1 is a composite material. The composite material comprises: 20 to 40 weight percent (wt.%) of a polymerizable component; 6 to 40 wt% of ceramic fibers; and 30 to 70 wt% nanoclusters. The wt% values of the composite are based on the total weight of the composite and add up to values of 100 wt%. Each of the ceramic fibers has a diameter and a length, the ceramic fibers have an arithmetic mean diameter of 0.3 to 5 microns, and fifty percent of the ceramic fibers have a length of at least 10 microns based on the total number of ceramic fibers, and ninety percent of the ceramic fibers have a length of no greater than 500 microns based on the total number of ceramic fibers.

Embodiment 2 is the composite of embodiment 1, wherein the aspect ratio of the arithmetic mean length of the ceramic fibers to the arithmetic mean diameter of the ceramic fibers is at least 10:1 (mean length: mean diameter).

Embodiment 3 is the composite of embodiment 2, wherein the aspect ratio is at most 150:1 (average length: average diameter).

Embodiment 4 is the composite of any of embodiments 1-3, wherein the ceramic fibers have an arithmetic mean diameter of 0.3 to 3 microns.

Embodiment 5 is the composite of any of embodiments 1-3, wherein the arithmetic mean diameter of the ceramic fibers is from 2 microns to 5 microns.

Embodiment 6 is the composite of any of embodiments 1-5, wherein the ceramic fibers are at least partially amorphous ceramic fibers.

Embodiment 7 is the composite of embodiment 6, wherein the ceramic fibers are completely amorphous ceramic fibers.

Embodiment 8 is the composite of any of embodiments 1-7, wherein the ceramic fibers have an arithmetic mean length of 50 to 250 micrometers.

Embodiment 9 is the composite of any of embodiments 1-8, wherein ninety percent of the ceramic fibers are no greater than 200 microns in length, based on a total number of the ceramic fibers.

Embodiment 10 is the composite of any of embodiments 1-9, wherein the composite comprises 6 to 30 or 10 to 20 weight percent ceramic fibers, based on the total weight of the composite.

Embodiment 11 is the composite of any of embodiments 1-10, wherein the ceramic fibers comprise alumina fibers, alumina-silica fibers, aluminum borosilicate fibers, zirconia-silica fibers, borosilicate glass fibers, silicate fibers modified with an alkali or alkaline earth metal, fused silica fibers, leached silica fibers, quartz fibers, glass fibers, or a combination thereof.

Embodiment 12 is the composite of any of embodiments 1-10, wherein the ceramic fibers are comprised of alumina-silica fibers, borosilicate glass fibers, or a combination thereof.

Embodiment 13 is the composite of any of embodiments 1 to 12, wherein the composite comprises up to 15 wt% nanoparticles.

Embodiment 14 is the composite of embodiment 13, wherein the composite comprises 2 to 12 weight percent nanoparticles.

Embodiment 15 is the composite of embodiment 13 or embodiment 14, wherein the nanoparticles are discrete non-fumed metal oxide nanoparticles.

Embodiment 16 is the composite of embodiment 15, wherein the discrete non-fumed metal oxide nanoparticles are discrete non-fumed heavy metal oxide nanoparticles.

Embodiment 17 is the composite of embodiment 16, wherein the discrete non-fumed metal oxide nanoparticles include both discrete non-fumed heavy metal oxide nanoparticles and discrete non-fumed non-heavy metal oxide nanoparticles.

Embodiment 18 is the composite of any of embodiments 1-17, wherein the composite comprises 35 to 64 wt% nanoclusters.

Embodiment 19 is the composite of any of embodiments 1-17, wherein the polymerizable component forms a hardened polymerizable component having a refractive index, and wherein the refractive index value of the ceramic fibers differs from the refractive index of the hardened polymerizable component by a value in a range of 0.1 or less.

Embodiment 20 is the composite of embodiment 19, wherein the difference between the refractive index value of the ceramic fibers and the refractive index of the hardenable polymerizable component is in the range of 0.05 or less.

Embodiment 21 is the composite of any of embodiments 1-20, wherein the ceramic fibers have a refractive index value of 1.40 to 1.65.

Embodiment 22 is the composite of embodiment 21, wherein the ceramic fibers have a refractive index value of 1.51 to 1.56.

Embodiment 23 is the composite of any of embodiments 1-22, wherein the polymerizable component is an ethylenically unsaturated compound.

Embodiment 24 is the composite of any of embodiments 1-23, further comprising an initiator selected from a free radical initiator, a photoinitiator, a thermally activated initiator, or a combination thereof.

Embodiment 25 is the composite of any of embodiments 1-24, further comprising a coupling agent, wherein the coupling agent provides a chemical bond between the ceramic fiber and the polymerizable component.

Embodiment 26 is the composite of embodiment 25, wherein the coupling agent is selected from an organosilane coupling agent, a titanate coupling agent, a zirconate coupling agent, an acidic coupling agent, or combinations thereof.

Embodiment 27 is the composite of any of embodiments 1-26, wherein the composite is hardened to become any of a dental restoration, a dental adhesive, a dental mill blank, a dental cement, a dental prosthesis, an orthodontic device, an orthodontic adhesive, a dental cast material, or a dental coating.

Embodiment 28 is the composite of any of embodiments 1-27, wherein the nanoclusters are silica-zirconia nanoclusters.

Embodiment 29 is the composite of embodiment 28, wherein the silica-zirconia nanoclusters are formed from primary particles, and wherein each of the primary particles has a diameter of 1 to 200 nanometers.

Embodiment 30 is the composite of any of embodiments 1-29, wherein the composite forms a cured composite having a radial tensile strength (DTS) of 65 megapascals (MPa) or greater.

Embodiment 31 is the composite of embodiment 30, wherein the composite forms a stiffened composite having a DTS of 75MPa or greater.

Embodiment 32 is the composite of any of embodiments 1-31, wherein the composite forms a stiffened composite having a flexural strength of 170MPa or greater.

Embodiment 33 is the composite of embodiment 32, wherein the composite forms a stiffened composite having a flexural strength of 180MPa or greater.

Embodiment 34 is the composite of any of embodiments 1-33, wherein the composite is formed to have a square root meter of 2.50 megapascals (MPa · m)^1/2) Or a greater fracture toughness.

Embodiment 35 is the composite of embodiment 34, wherein the composite is formed to have 2.80 MPa-m^1/2Or a greater fracture toughness.

Embodiment 36 is the composite of any of embodiments 1-30, wherein the composite is formed to have a DTS of 65MPa or greater, a flexural strength of 170MPa or greater, and 2.50 MPa-m^1/2Or greater fracture toughness.

Embodiment 37 is the composite of any of embodiments 1-36, wherein the composite forms a hardened composite having a polish retention of 40 gloss units or greater at 60 ° after 6000 brushing cycles.

Embodiment 38 is the composite of any of embodiments 1-37, wherein a ratio of the wear resistance of a hardened composite formed from the composite to the wear resistance of a hardened composite formed from a control composite is 2.0 or less, wherein the control composite has the same composition as the composite except that no ceramic fibers are included.

Embodiment 39 is a dental product. The dental product is prepared by hardening the composite material of any of the preceding embodiments 1 to 38.

Embodiment 40 is the dental product of embodiment 39, wherein the dental product is selected from a dental restoration, a dental adhesive, a dental mill blank, a dental cement, a dental prosthesis, an orthodontic device, an orthodontic adhesive, a dental cast material, an artificial crown, an anterior filling, a posterior filling, a cavity liner, or a dental coating.

Embodiment 41 is a method of making a composite material. The method includes obtaining a plurality of components and mixing the plurality of components to produce a composite material. The component comprises: 20 to 40 weight percent of a polymerizable component; 6 to 40 wt% of ceramic fibers; and 30 to 70 wt% nanoclusters. The wt% values of the composite are based on the total weight of the composite and add up to values of 100 wt%. Each of the ceramic fibers has a diameter and a length, the ceramic fibers have an arithmetic mean diameter of 0.3 to 5 microns, and fifty percent of the ceramic fibers have a length of at least 10 microns based on the total number of ceramic fibers, and ninety percent of the ceramic fibers have a length of no greater than 500 microns based on the total number of ceramic fibers.

Embodiment 42 is the method of embodiment 41, wherein the plurality of components further comprise up to 15 weight percent nanoparticles, based on the total weight of the composite.

Embodiment 43 is the method of embodiment 42, wherein the composite material comprises 2 to 12 weight percent nanoparticles.

Embodiment 44 is the method of embodiment 42 or embodiment 43, wherein the nanoparticles are discrete non-fumed metal oxide nanoparticles.

Embodiment 45 is the method of embodiment 44, wherein the discrete non-fumed metal oxide nanoparticles are discrete non-fumed heavy metal oxide nanoparticles.

Embodiment 46 is the method of embodiment 45, wherein the discrete non-fumed metal oxide nanoparticles comprise both discrete non-fumed heavy metal oxide nanoparticles and discrete non-fumed non-heavy metal oxide nanoparticles.

Embodiment 47 is the method of embodiments 41-46, wherein the aspect ratio of the arithmetic mean length of the ceramic fibers to the arithmetic mean diameter of the ceramic fibers is at least 10:1 (mean length: mean diameter).

Embodiment 48 is the method of embodiment 47, wherein the aspect ratio is at most 150:1 (average length: average diameter).

Embodiment 49 is the method of any one of embodiments 41 to 48, wherein the ceramic fibers have an arithmetic mean diameter of 0.3 to 3 microns.

Embodiment 50 is the method of any one of embodiments 41 to 48, wherein the arithmetic mean diameter of the ceramic fibers is from 2 microns to 5 microns.

Embodiment 51 is the method of any one of embodiments 41 to 50, wherein the ceramic fibers are at least partially amorphous ceramic fibers.

Embodiment 52 is the method of embodiment 51, wherein the ceramic fibers are completely amorphous ceramic fibers.

Embodiment 53 is the method of any one of embodiments 41 to 52, wherein the ceramic fibers have an arithmetic mean length of 50 to 250 micrometers.

Embodiment 54 is the method of any one of embodiments 41-53, wherein ninety percent of the ceramic fibers are no greater than 500 microns in length, based on a total number of the ceramic fibers.

Embodiment 55 is the method of any one of embodiments 41 to 54, wherein the composite comprises 6 to 30 or 10 to 20 weight percent ceramic fibers, based on the total weight of the composite.

Embodiment 56 is the method of any one of embodiments 41 to 55, wherein the ceramic fibers comprise alumina fibers, alumina-silica fibers, alumino-borosilicate fibers, zirconia-silica fibers, borosilicate glass fibers, silicate fibers modified with an alkali or alkaline earth metal, fused silica fibers, leached silica fibers, quartz fibers, glass fibers, or a combination thereof.

Embodiment 57 is the method of any one of embodiments 41 to 56, wherein the ceramic fibers are comprised of alumina-silica fibers, borosilicate glass fibers, or a combination thereof.

Embodiment 58 is the method of any one of embodiments 41 to 57, wherein the composite material comprises 35 to 64 wt% nanoclusters.

Embodiment 59 is the method of any one of embodiments 41 to 58, wherein the ceramic fiber has a refractive index value of 1.40 to 1.65.

Embodiment 60 is the method of embodiment 59, wherein the ceramic fibers have a refractive index value of 1.51 to 1.56.

Embodiment 61 is the method of any one of embodiments 41 to 60, wherein the polymerizable component is an ethylenically unsaturated compound.

Embodiment 62 is the method of any one of embodiments 41 to 61, wherein the plurality of components further comprises an initiator selected from a free radical initiator, a photoinitiator, a thermally activated initiator, or a combination thereof.

Embodiment 63 is the method of any one of embodiments 41 to 62, wherein the plurality of components further comprises a coupling agent, wherein the coupling agent provides a chemical bond between the ceramic fiber and the polymerizable component.

Embodiment 64 is the method of embodiment 63, wherein the coupling agent is selected from an organosilane coupling agent, a titanate coupling agent, a zirconate coupling agent, an acidic coupling agent, or a combination thereof.

Embodiment 65 is the method of any one of embodiments 41 to 64, wherein the nanoclusters are silica-zirconia nanoclusters.

Embodiment 66 is the method of embodiment 65, wherein the silica-zirconia nanoclusters are formed from primary particles, and wherein each of the primary particles has a diameter of 1 to 200 nanometers.

Embodiment 67 is the method of any of embodiments 41-66, further comprising hardening the composite material to form a dental product.

Embodiment 68 is the method of embodiment 67, wherein the dental product has a refractive index, and wherein the refractive index value of the ceramic fiber differs from the refractive index of the dental product by a value in the range of 0.1 or less.

Embodiment 69 is the method of embodiment 68, wherein the difference between the refractive index value of the ceramic fiber and the refractive index of the hardenable polymerizable component is in the range of 0.05 or less.

Embodiment 70 is the method of any of embodiments 67 to 69, wherein the dental product comprises any of a dental restoration, a dental adhesive, a dental mill blank, a dental cement, a dental prosthesis, an orthodontic appliance, an orthodontic adhesive, a dental casting material, or a dental coating.

Embodiment 71 is a method of using a composite material. The method comprises the following steps: placing the composite material of any one of embodiments 1 to 36 near or on a tooth surface; changing the shape of the composite material near or on the tooth surface; and hardening the composite material.

Embodiment 72 is the method of embodiment 71, wherein altering the shape of the composite material near or on the surface of the tooth comprises forming the composite material into a dental product selected from a dental prosthesis, an orthodontic device, a crown, an anterior filling, a posterior filling, or a cavity liner.

Embodiment 73 is the method of embodiment 71 or embodiment 72, further comprising polishing the composite material after hardening the composite material.

Embodiment 74 is a kit. The kit includes: the composite according to any one of embodiments 1 to 36; and at least one container for containing the composite material.

Embodiment 75 is the kit of embodiment 77, further comprising at least one dental component selected from the group consisting of: cements, adhesives, abrasives, polishes, instruments, software, milling machines, CAD/CAM systems, composites, china, stains, burr, impression materials, dental mill blanks, or combinations thereof.

Examples

Advantages and embodiments of this invention are further illustrated by the following examples, but the particular materials and amounts thereof recited in these examples, as well as other conditions and details, should not be construed to unduly limit this invention. All parts and percentages are by weight unless otherwise indicated.

Test method

Fiber length measurement

The length of the ceramic fibers was determined using an optical microscope (Keyence VHX digital microscope system, Keyence Corporation, Itasca, IL) with analytical software. The samples were prepared by spreading a representative sample of ceramic fibers on a double-sided tape attached to a glass slide and measuring the length of at least 50 ceramic fibers at 100 x magnification. The mean length and the corresponding Standard Deviation (SD) were calculated and recorded.

Fiber diameter measurement

The diameter of the ceramic fiber is determined using one of two methods. For fibers greater than 2 microns in diameter, a Keyence VHX digital microscope was used at 1,000 times magnification. The samples were prepared by spreading a representative sample of ceramic fibers on a double-sided tape attached to a glass slide and measuring the diameter of at least 50 ceramic fibers at 1,000 times magnification. For fibers less than 2 microns, there were about 500 to 100 individual fibers in the field of view using Zeiss scanning electron Microscopy (Carl Zeiss microscopical LLC, Thornbush, NY) at a magnification of 3,000 to 15,000 times. The fiber sample was adhered to the microscope stub using a conductive double-sided tape and coated with Au — Pd. About 40 to 100 individual fibers were measured for each sample. The average diameter was calculated and recorded.

Bending strength testing method

Each sample was prepared by extruding the uncured composite material into a 2mm by 25mm quartz glass die to form a test bar. Two XL3000 dental curing lamps (3M Corporation, Maplewood, MN) were used to cure test bars of the composite material in a quartz glass mold. The exit window of one lamp was placed over the center of the test bar and the composite was cured for 20 seconds. Next, using two lamps in series, the exit window of the lamp was placed over the uncured ends of the test rod and the composite material on each end of the rod was cured simultaneously for 20 seconds. The test bar was turned over and the curing protocol was repeated. The composite cured test bars were ejected from the quartz glass mold. Prior to testing, cured test bars of the composite were immersed in deionized water (37 ℃) for about 24 hours.

The flexural strength of each cured test bar of the composite was measured according to ANSI/ADA (american national standards/american dental association) specification No. 27(1993) with an Instron tester (Instron 5944, Instron Corporation, Canton, MA) at a jaw speed of 0.75 mm/min and a span of 20 mm. For each specimen, five test bars were evaluated and the average flexural strength (MPa ) reported.

Fracture toughness testing method

Each sample was prepared by extruding the uncured composite material into a 3mm by 5mm by 25mm quartz glass die to form a test bar. Two XL3000 dental curing lamps (3M company) were used to cure test bars of composite material in a quartz glass mold. The exit window of one lamp was placed over the center of the test bar and the composite was cured for 20 seconds. Next, using two lamps in series, the exit window of the lamp was placed over the uncured ends of the test rod and the composite material on each end of the rod was cured simultaneously for 20 seconds. The test bar was turned over and the curing protocol was repeated. The test bars of cured composite material were ejected from the quartz glass mold. A notch was cut in the center of the test bar using a wafer blade with a 0.15mm cut and an ISOMET low speed saw (Buehler, Lake Bluff, IL). The notch is about 2mm deep. Prior to testing, cured test bars of the composite were immersed in deionized water (37 ℃) for about 24 hours.

The fracture toughness of each cured test bar was measured using an Instron tester (Instron 5944, Instron corporation) at a chuck speed of 0.75 mm/min. Toughness was calculated according to ASTM 399-05. For each sample, five test bars were evaluated and the average flexural strength (MPa · m) reported^1/2)。

Radial tensile strength testing method

Each sample was prepared by extruding the uncured composite material into a 4mm inner diameter glass tube and capping the ends of the tube with silicone rubber plugs. The filled tube was compressed axially at a pressure of about 40psi for 5 minutes. The tube was then photocured with continuous rotation of the tube for one minute using an XL1500 dental curing lamp (3M). The cured composite tube was then cut with a diamond saw to form individual 2mm sections. The cured composite material is removed from each segment to provide individual test disks. Each test tray was immersed in deionized water (37 ℃) for about 24 hours prior to testing.

The radial tensile strength of each cured test disc of the composite was measured according to ISO specification 7489 (or American Dental Association (ADA) specification No. 27) using an Instron tester (Instron 5966, Instron corporation) at a collet speed of 1 mm/min. For each specimen, nine discs were evaluated and the average radial tensile strength (MPa) reported.

Gloss retention after toothbrush abrasion test method

Samples of the uncured composite were formed into sheets 2mm thick by 21mm long by 10mm wide using a stainless steel mold. The uncured composite was flat pressed between polyester film sheets at 6000psi to 10,000psi using a Carver press (Wabash, IN, indiana) and using a press having a wavelength of 455nm, 850mW/cm²An array of intensity LEDs (light emitting diodes) (Clear Stone Technology, Hopkins, MN) was cured for 20 seconds with control unit CF2000, LED array JL 2-455F-90. The resulting sample pieces were removed from the mold and polished to high gloss using an Ecomet 4 variable speed grinder-polisher equipped with an Automet 2 power head (Calif.). High gloss is achieved by using continuous fine grinding and polishing media. First, 320 mesh silicon carbide abrasive paper was used, followed by 600 mesh silicon carbide abrasive paper (sandpaper from 3M company). Polishing was continued with 9 micron diamond paste, then with 3 micron paste, and finally with 0.05 micron polishing slurry (both polishing agent and polishing slurry were purchased from tagete). Each polished sheet was stored submerged in water at 37 ℃ for about 24 hours.

The gloss retention of each sheet was measured by testing the polished surface with toothbrush abrasion. The sheet was held in a jig with the gloss side up. Initial gloss (60 degree gloss) was measured using a Novo-Curve gloss meter (Rhopoint instruments, st. leonards-on-the-Sea, East suslex, UK) according to ASTM D2457. The jig was placed in the cavity of an automatic scrubber in which 5mL of an abrasive slurry consisting of 1:1 camier daily restorative toothpaste (Procter & Gamble Company, Cincinnati, OH) and water was placed on the sheet. The tablets were then brushed with 47 tufts of Acclean toothbrushes (Henry Schein, Melville, N.Y.) under a load of 450gf (gram-force). The sheet was subjected to a total of 6000 brushing cycles, and the gloss was measured after each 1500 brushing cycles. Five milliliters of fresh slurry was added to the sheet after each intermediate gloss measurement. For each sample, the surface of at least three pieces was evaluated and the average gloss value (sixty degree gloss) was reported.

Material

"BisEMA-6" refers to ethoxylated (6 mole ethylene oxide) bisphenol A dimethacrylate, as further described in U.S. Pat. No. 6,030,606, available as "CD 541" from Sartomer Co., Inc., Exton, PA of Exxon, Pa.

"BisGMA" refers to 2, 2-bis [4- (2-hydroxy-3-methacryloxypropoxy) phenyl ] propane (also known as bisphenol A diglycidyl ether methacrylate) having CAS registry number 1565-94-2.

"BHT" refers to butylated hydroxytoluene (2, 6-di-tert-butyl-4-methylphenol) with CAS registry number 128-37-0.

"BZT" refers to 2- (2 '-hydroxy-5' -methacryloyloxyethylphenyl) -2H-benzotriazole, CAS registry number 96478-09-0, available as "TINUVIN R796" from Ciba Specialty Chemicals Corporation, Tarrytown, N.Y..

"CPQ" refers to camphorquinone and CAS registry number 10373-78-1.

"DPIHFP" or "DPIPF 6" refers to diphenyliodonium hexafluorophosphate having CAS registry number 58109-40-3, available from the Afahertson group of Achekun, Wald Hill, Mass. (Johnson Matthey, Alfa Aesar Division, Ward Hill, Mass.).

"ENMAP" refers to ethyl N-methyl-N-phenyl-3-aminopropionate (also known as ethyl N-methyl-N-phenyl-. beta. -alanine), CAS registry No. 2003-76-1, prepared by the method described by Adamson et al (JCSOA9, J.Chem.Soc., 1949, pp.144-152 (JCSOA 9; J.chem.Soc.; 1949; spl.144-152)), which is incorporated herein by reference.

"GENIOSIL GF-31" or "GF-31" refers to 3-methacryloxypropyltrimethoxysilane, available from Wacker Chemie AG, Munich, Germany, Inc.

"IRGACURE 819" refers to bis (2,4, 6-trimethylbenzoyl) phenylphosphine oxide photoinitiator, CAS registry number 162881-26-7, available from Ciba specialty Chemicals, Inc. or from Sigma Aldrich Inc.

"PEG 600 DM" refers to poly (ethylene glycol) dimethacrylate, having an average molecular weight of about 600, available from Saedoma.

"TEGDMA" refers to triethylene glycol dimethacrylate having CAS registry number 109-16-0 and available from Sartomer.

"UDMA" refers to dicarbamate dimethacrylate, CAS registry number 72869-86-4, available under the trade designation "ROHAMERE 6661-0" from Rohm America LLC, Piscataway, NJ, Piscataway, N.J..

Filler material

"S/T silica/zirconia nanoclusters" refers to silane treated silica-zirconia nanocluster fillers prepared substantially as described in U.S. patent 6,730,156, column 25, lines 50 through 63 (preparation a) and column 25, lines 64 through 26, line 40 (preparation B), with minor modifications, including in the use of NH₄The silanization was performed in 1-methoxy-2-propanol (instead of water) with OH adjusted to pH about 8.8 (instead of pH 3-3.3 with trifluoroacetic acid) and S/T silica/zirconia nanoclusters were obtained by gap drying (instead of spray drying).

"S/T20 nm silica nanoparticles" refers to a silane-treated silica nanoparticle filler having a nominal particle size of about 20 nanometers, prepared essentially as described in U.S. patent 6,572,693, column 21, lines 63 through 67 (nanoscale particle filler, type # 2).

"S/T nano zirconia nanoparticles" refers to a silane treated zirconia nanoparticle filler prepared from a zirconia sol essentially as described in U.S. patent 8,647,510, column 36, line 61 to column 37, line 16 (examples 11A to IER). The zirconia sol was added to an equivalent of 3-methacryloxypropyltrimethoxysilane in 1-methoxy-2-propanol (1.1 mmol of 3-methacryloxypropyltrimethoxysilane per gram of nano zirconia to be surface treated). Under stirring, the mixture is mixedThe mixture was heated to about 85 ℃ for 3 hours. The mixture was cooled to 35 ℃ with NH₄OH adjusts the pH to about 9.5 and the mixture is heated to about 85 ℃ for 4 hours with stirring. The resulting S/T nano zirconia was isolated by removing the solvent via gap drying. S/T nanozirconia can also be made as described in U.S. Pat. No. 7,649,029 column 19, line 39 to column 20, line 41 (Filler I), except that the blend of Silquest A-174 and A-1230 is replaced with 3-methacryloxypropyltrimethoxysilane and the solvent is further removed via gap drying.

Ceramic fiber

Ceramic fiber A

Alumina-silicate ceramic fibers (3.60 microns in average diameter, available under the trade designation "SAFFIL LDM" from Unifrax LLC of nicaraga, ny) were chopped using an IKA 8510.1 cutting abrading head (available from kel pamer, francisco) for a continuous feed abrading drive operating at 3000RPM, placed in a solution of ethyl acetate, GF-31 silane (0.015g/g fiber), and 30% aqueous ammonia solution (0.02g/g fiber).

The length of the staple fibers was measured according to the method described above. The median length of the fibers was 153 microns. The average length of the fibers was 198 microns (SD 141). With respect to distribution, 96% of the fibers are less than 500 microns in length, and 64% of the fibers are less than 200 microns in length. The calculated ratio of average fiber length to average fiber diameter was 55.

Ceramic fiber B

Alumina-silicate ceramic fibers (average diameter 4.70 microns, available from Unifrax LLC under the trade designation "SAFFIL 3D + Fiber") were chopped using an IKA2870900MF 10.1.1 cutting mill head for a continuous feed mill drive operating at 3000 RPM. The staple fibers were silane treated by placing them in a solution of ethyl acetate, GF-31 silane (0.015g/g fiber) and 30% aqueous ammonia solution (0.02g/g fiber). Enough ethyl acetate was used to make the mixture flowable. The fibers were stirred for about 24 hours, removed from the solution, and then dried at 80 ℃ for about 1.5 hours to provide ceramic fibers B.

The length of the staple fibers was measured according to the method described above. The median length of the fibers was 59 microns. The average length of the fibers was 88 microns (SD 59). With respect to distribution, the length of all fibers is less than 500 microns, and 85.6% of the fibers are less than 200 microns in length. The calculated ratio of average fiber length to average fiber diameter was 19.

Ceramic fiber C

Glass fibers (average diameter 0.35 microns, available under the trade designation "JM MICRO-STRAND 106-.

The length of the staple fibers was measured according to the method described above. The median length of the fibers was 34 microns. The average length of the fibers was 48 microns (SD-38). With respect to distribution, the length of all fibers is less than 500 microns, and 99% of the fibers are less than 200 microns in length. The calculated ratio of average fiber length to average fiber diameter is 138.

Ceramic fiber D

Glass fibers (average diameter 2.05 microns, available under the trade designation "JM MICRO-STRAND 110X-481" from John Manfel.) were chopped using an IKA2870900MF 10.1.1 cutting abrading head for a continuous feed abrading drive operating at 3000RPM, silane treated by placing the staple fibers in a solution of ethyl acetate, GF-31 silane (0.01g/g fiber), and 30% aqueous ammonia solution (0.02g/g fiber). The mixture was made flowable using sufficient ethyl acetate, the fibers were stirred for about 24 hours, removed from the solution, and then dried at 80 ℃ for about 1.5 hours to provide ceramic fibers D.

The length of the staple fibers was measured according to the method described above. The median length of the fibers was 42 microns. The average length of the fibers was 57 microns (SD 55). With respect to distribution, the length of all fibers is less than 500 microns, and 94% of the fibers are less than 200 microns in length. The calculated ratio of average fiber length to average fiber diameter was 28.

Ceramic fiber E

Ceramic alumina-silica fibers (average diameter 0.92 microns, available from Unifrax LLC corporation under the trade designation "FIBERFRAX Ceramic Fiber Bulk 7000") were chopped using an IKA2870900MF 10.1.1 cutting mill head for a continuous feed mill drive operating at 3000 RPM. The staple fibers were silane treated by placing them in a solution of ethyl acetate, GF-31 silane (0.01g/g fiber) and 30% aqueous ammonia solution (0.02g/g fiber). Enough ethyl acetate was used to make the mixture flowable. The fibers were stirred for about 24 hours, removed from the solution, and then dried at 80 ℃ for about 1.5 hours to provide ceramic fibers E.

The length of the staple fibers was measured according to the method described above. The median length of the fibers was 27 microns. The average length of the fibers was 37 microns (SD ═ 29), and the length of all fibers was less than 200 microns. The calculated ratio of average fiber length to average fiber diameter was 40.

Ceramic fiber F

Alumina-silicate ceramic fibers having 50% by weight alumina and 50% silica (10 to 15 microns in diameter) were prepared by a sol-gel process as described in U.S. patent 4,047,965, column 15, line 5 to column 16, line 55 (example 1), with the modification that the ratio of alumina to silica by weight was 1:1 and the fibers were calcined to 1100 ℃. The fibers were chopped by hand using a razor blade over a rubber pad to make fibers having a length of about 200 microns. The staple fibers were silane treated by placing them in a solution of ethyl acetate, GF-31 silane (0.01g/g fiber) and 30% aqueous ammonia solution (0.02g/g fiber). Enough ethyl acetate was used to make the mixture flowable. The fibers were stirred for about 24 hours, removed from the solution, and then dried at 80 ℃ for about 1.5 hours to provide ceramic fibers F.

Ceramic fiber G

Ceramic fibers G were prepared by silane treating # 381/32 inch ground glass fibers (available from fiber glass Developments Corporation, Brookville, OH.) the manufacturer reported the fibers to have an average diameter of 16 microns and an average length of 230 microns.

Ceramic fiber H

Amorphous aluminoborosilicate Ceramic Fibers (available from 3M company under the designation "NEXTEL 312Ceramic Fiber," reporting a diameter of 10 to 12 microns) were chopped into lengths of about 200 microns using Engineered Fibers Technology, LLC (LLC, Shelton, CT) of Shelton, connecticut. The staple fibers were silane treated by placing them in a solution of ethyl acetate, GF-31 silane (0.01g/g fiber) and 30% aqueous ammonia solution (0.02g/g fiber). Enough ethyl acetate was used to make the mixture flowable. The fibers were stirred for about 24 hours, removed from the solution, and then dried at 80 ℃ for about 1.5 hours to provide ceramic fibers H.

Ceramic fiber I

Amorphous aluminoborosilicate Ceramic fibers (available from 3M company under the designation "NEXTEL 312Ceramic Fiber," reporting diameters of 10 to 12 microns) were chopped to a length of about 200 microns using an IKA2870900MF 10.1.1 cutting abrading head for a continuous feed abrading drive operating at 3000 RPM. The staple fibers were silane treated by placing them in a solution of ethyl acetate, GF-31 silane (0.01g/g fiber) and 30% aqueous ammonia solution (0.02g/g fiber). Enough ethyl acetate was used to make the mixture flowable. The fibers were stirred for about 24 hours, removed from the solution, and then dried at 80 ℃ for about 1.5 hours to provide ceramic fibers I.

Resin A

Polymerizable component resin A was prepared by mixing the components shown in Table 1 until all the components were uniformly mixed.

TABLE 1 formulation of resin A

Examples 1 to 9 and comparative examples A to E

Examples 1 to 9(EX-1 to EX-9) and comparative examples a to E (CE-a to CE-E) of composite materials were prepared by mixing the components shown in table 2 to table 4 using a FlakTek model DAC150.1 FVZ high shear speed mixer (FlakTek Incorporated, Landrum, SC). The components were mixed to obtain a homogeneous paste. The flexural strength and fracture toughness of the composites were measured according to the procedure described above and the results are reported in tables 5 and 6. The radial tensile strength of the composite was measured according to the method described above and the results are reported in table 7. Gloss retention after abrasion of the toothbrush of the composite was measured according to the above method, and the results are reported in tables 8 and 9.

Table 2: composite formulations comprising different ceramic fibers of examples 1 to 5(EX-1 to EX-5)

Components	EX-1	EX-2	EX-3	EX-4	EX-5
						Resin A (% by weight)	20.0	20.0	24.0	24.0	22.0
S/T nano zirconia nanoparticles (% by weight)	4.2	4.2	4.0	4.0	4.1
						S/T20 nm silica nanoparticles (% by weight)	7.8	7.8	7.4	7.4	7.6
S/T silica/zirconia nanocluster (% by weight)	51.0	51.0	48.4	48.4	49.7
						Ceramic materialFiber A (% by weight)	17.0	0	0	0	0
Ceramic fiber B (% by weight)	0	17.0	0	0	0
						Ceramic fiber C (% by weight)	0	0	16.2	0	0
Ceramic fiber D (% by weight)	0	0	0	16.2	0
						Ceramic fiber E (% by weight)	0	0	0	0	16.6

Table 3: examples 6 to 9(EX-6 to EX)-9) composite formulation

Components	EX-6	EX-7	EX-8	EX-9
					Resin A (% by weight)	20.0	20.0	24.0	24.0
S/T nano zirconia nanoparticles (% by weight)	4.2	4.2	4.0	4.0
					S/T20 nm silica nanoparticles (% by weight)	7.8	7.8	7.4	7.4
S/T silica/zirconia nanocluster (% by weight)	61.2	40.8	58.1	38.8
					Ceramic fiber A (% by weight)	6.8	27.2	0	0
Ceramic fiber C (% by weight)	0	0	6.5	25.8

Table 4: composite formulations of comparative examples A to E (CE-A to CE-E) comprising different ceramic fibers

Components	CE-A	CE-B	CE-C	CE-D	CE-E
						Resin A (% by weight)	22.0	20.5	24.0	24.0	22.0
S/T nano zirconia nanoparticles (% by weight)	4.1	4.0	4.2	4.2	4.2
						S/T20 nm silica nanoparticles (% by weight)	7.6	7.5	7.8	7.8	7.8
S/T silica/zirconia nanocluster (% by weight)	66.3	49.5	51.0	51.0	51.0
						Ceramic fiber F (% by weight)	0	16.5	0	0	0
Ceramic fiber G (% by weight)	0	0	17.0	0	0
						Ceramic fiber H (% by weight)	0	0	0	17.0	0
Ceramic fiber I (% by weight)	0	0	0	0	17.0

TABLE 5 average flexural Strength measurement

Examples	Average flexural strength (MPa) (n ═ 5)	Standard deviation of
			EX-1	201.1	6.7
EX-2	189.2	3.7
			EX-3	177.7	17.6
EX-4	190.8	6.0
			EX-5	190.0	4.1
EX-6	157.9	14.9
			EX-7	209.5	1.6
EX-8	161.9	12.2
			EX-9	157.8	16.6
CE-A	150.8	6.3
			CE-B	160.0	8.9
CE-D	156.2	5.1

TABLE 6 average fracture toughness measurement

TABLE 7 average radial tensile Strength measurement

TABLE 8 gloss Retention after toothbrush abrasion measurement

TABLE 9 gloss Retention after toothbrush abrasion measurement

All patents and patent applications mentioned above are hereby expressly incorporated by reference. In the event of any inconsistency between the disclosure of the present application and the disclosure of any document incorporated by reference herein, the disclosure of the present application shall prevail. The above-described embodiments are all illustrations of the present invention, and other configurations are also possible. Accordingly, the present invention should not be considered limited to the embodiments described in detail above and illustrated in the drawings, but should be defined only by the proper scope of the appended claims and equivalents thereof.