KR20070023747A - Dental compositions containing nanozirconia fillers - Google Patents

Abstract

The present invention features ionomer compositions containing nanozirconia fillers. The composition can be used in a variety of dental and orthodontic applications, such as adhesives, cements, restorations, coatings and sealants.

Nano zirconia fillers, ionomers, hardenable dental compositions

Description

Dental compositions containing nano zirconia fillers {DENTAL COMPOSITIONS CONTAINING NANOZIRCONIA FILLERS}

The present invention relates to hardenable dental and orthodontic compositions filled with zirconia nanoparticles. More particularly, the present invention relates to ionomer and resin modified ionomer compositions containing nanozirconia fillers. The composition can be used for a variety of uses, such as adhesives, cements, restorations, coatings and sealants.

Repair of caries teeth, including tooth decay, caries dentin or carved enamel, is often performed using a dental adhesive followed by a dental material (e.g., restorative material) sequentially to the tooth. Similar compositions are used to bond orthodontic devices to teeth (typically using orthodontic adhesives). Often, various pretreatment methods are used to promote the bonding of the adhesive to dentin or enamel. Typically, this pretreatment step involves, for example, etching with an inorganic or organic acid and then priming to improve the bond between the tooth and the adhesive placed thereon.

Various dental and orthodontic adhesives, cements and restorations are currently available. Compositions comprising fluoroaluminosilicate glass fillers (also known as glass ionomers or "GI" compositions) are the most widely used type of dental materials. These compositions include filling and repairing caries lesions; Bonding of crowns, inlays, dentures or orthodontic bands; Caries lining; Core reconfiguration; And widespread uses such as hole and gap closure.

There are currently two main classes of glass ionomers. The first class, known as conventional free ionomers, generally comprises homopolymers or copolymers of α, β-unsaturated carboxylic acids, fluoroaluminosilicate (“FAS”) glasses, water and optionally chelating agents such as tartaric acid as main components. It contains. These conventional glass ionomers are typically supplied in powder / liquid formulations and mixed just prior to use. The mixture is self-hardened in the dark due to the acidic repeating units of polycarboxylic acids and the ionic acid-base reaction of the cations leached from the basic glass.

The second major class of glass ionomers is known as hybrid glass ionomers or resin-modified glass ionomers (“RMGI”). Like conventional glass ionomos, RMGI uses FAS glass. RMGI also contains homopolymers or copolymers of α, β-unsaturated carboxylic acids, FAS glass and water, but the organic portions of RMGI are different. In one type of RMGI, the polyacid is substituted or end capped with a portion of an acidic repeating unit having a curable pendant group, and modified, and a photoinitiator is added to provide a second curing mechanism. Typically acrylate or methacrylate groups are used as curable pendant groups. In another type of RMGI, the composition comprises a polycarboxylic acid, acrylate or methacrylate-functional monomer or polymer, and a photoinitiator. The polyacid may be optionally substituted or end capped with a portion of an acidic repeating unit having a curable pendant group. Redox- or other chemical curing systems may be used in place of or in addition to photoinitiator systems. RMGI compositions are generally formulated into a powder / liquid or paste / paste system and contain water upon mixing and application. This can be partially or fully hardened in the dark due to the ionic reaction of the acidic repeat units of the polycarboxylic acids and the cations leached from the glass, and commercially available RMGI products also typically contain cement in the light of a dental curing lamp. Cures on exposure.

Glass ionomer compositions provide many important advantages. For example, since glass fluoride glass from glass ionomers tends to be more than other classes of dental compositions, such as metal oxide cements, compomer cements, or fluorinated composites, glass ionomers have been shown to provide improved carcinogenesis protection. I think. Another advantage of the glass ionomer material is that the clinical adhesion of such cement to the teeth is very good, providing a high retention restoration. Conventional glass ionomers do not require an external cure initiation mode, and therefore can generally be placed in bulk as a fill material without the need to layer in thick restorations.

One of the drawbacks of conventional glass ionomers is that they are technically somewhat sensitive when manually mixing these compositions. They are typically prepared from powder components and liquid components, so weighing and mixing operations are necessary before use. The accuracy of these tasks depends on the skills and abilities of some operators. In manual mixing, the powder and liquid components are generally mixed on paper using a spectula. The mixing operation must be carried out within a short time and skilled techniques are required to ensure that the material exhibits the desired properties (ie the performance of the cement can depend on the mixing ratio, the mode of mixing and the integrity of the mixing). Alternatively, some of these inconveniences and technical sensitivities have been improved by using powdered liquid capsule dispersion systems containing suitable fractions of powder and liquid components. The capsules provide a suitable fraction of the powder and liquid components, but a capsule activation step is still needed which combines the two components and then mechanically mixes in a dental grinder.

Conventional glass ionomers can also be quite brittle, as evidenced by their relatively low flexural strength. Thus, restorations made from conventional glass ionomers tend to break well under load. In addition, glass ionomers are characterized by their relatively poor aesthetics, often due to their high visual opacity (ie, cloudiness), especially when contacted with water in the initial hardening stage.

Compared with conventional glass ionomers, cured RMGI typically has increased strength properties (eg, flexural strength), tends to be less mechanically crushed, and typically requires primers or conditioners for proper tooth adhesion. .

<Overview of invention>

The present invention features suitable ionomer compositions containing nanozirconia fillers that provide compositions having improved properties over previous ionomer compositions. In particular, the inclusion of at least one nanozirconia filler provides an ionomer system that is optically translucent and radiopaque. Nanozirconia is surface modified with silanes to assist incorporation of nanozirconia into ionomer compositions that generally contain polyacids that interact with nanozirconia to cause coagulation and aggregation that result in undesirable visual opacity.

Thus, in one aspect the invention is a polyacid; Acid-reactive fillers; Nanozirconia fillers having a plurality of silane-containing molecules adhered to the outer surface of the zirconia particles; And a hardenable dental composition comprising water. In one embodiment, the composition further comprises a polymerizable component. In general, the polymerizable component is an ethylenically unsaturated compound, optionally with acid functionality.

The polyacid component of the composition typically includes a polymer having a plurality of acidic repeating groups. The polymer may be substantially free of polymerizable groups, or alternatively may comprise a plurality of polymerizable groups.

Acid-reactive fillers are generally selected from metal oxides, glass, metal salts and combinations thereof. Typically, the acid-reactive filler comprises FAS glass. Typically, ionomer compositions use reactive glass to provide radiopacity. Nanozirconia incorporation into the composition allows for the formulation of radiopaque, optically translucent ionomer compositions with less acid-reactive filler than previous GI and RMGI compositions. Thus, in one embodiment the composition of the present invention comprises less than 50% by weight of acid-reactive filler, typically FAS glass.

In another embodiment of the present invention, the acid-reactive filler typically comprises an oxyfluoride material which is nanostructured, for example providing a nanoparticle form. Generally, the acid-reactive oxyfluoride material is non-fused, at least one trivalent metal (eg, aluminum, lanthanum, etc.), oxygen, fluorine and at least one alkaline earth metal (eg, strontium, Calcium, barium, and the like). The oxyfluoride material may be in the form of a coating on particles or nanoparticles, such as metal oxide particles (eg silica).

The compositions of the present invention may also contain one or more optional additives, such as other fillers, pyrogenic fillers, fluoride sources, whitening agents, caries preventive agents (e.g. xylitol), remineralizing agents (e.g. , Calcium phosphate compounds), enzymes, breath fresheners, anesthetics, coagulants, acid neutralizers, chemotherapeutic agents, immune response modifiers, medicines, indicators, dyes, pigments, wetting agents, tartaric acid, chelating agents, surfactants, Buffers, viscous modifiers, thixotrope, polyols, antibacterial agents, anti-inflammatory agents, antifungal agents, stabilizers, dry mouth cure agents, desensitizers and combinations thereof.

The composition of the present invention may further comprise a photoinitiator system and / or a redox reaction curing system.

In addition, the composition may be provided in the form of a multi-part system in which the various components are divided into two or more separate parts. Typically, the composition is a two-part system such as a paste-paste composition, a paste-liquid composition, a paste-powder composition or a powder-liquid composition.

As disclosed above, one of the features of the present invention is to provide a radiopaque, optically translucent ionomer composition with less acid-reactive filler than conventional glass ionomers. Such a system, for example, is easier to disperse and mix compared to a powder-liquid system, thereby facilitating the preparation of a two-part paste-paste composition.

The compositions according to the invention are useful for a variety of dental and orthodontic applications, including dental restorations, dental adhesives, dental cements, tooth decay liners, orthodontic adhesives, dental sealants and dental coatings. The composition can be used to prepare dental articles, for example, by hardening them to form dental mill blanks, dental crowns, dental fillers, dental prostheses and orthodontic devices.

The ionomer compositions of the invention have good aesthetics, low visual opacity (typically less than about 0.50 when hardened, as measured by the visual opacity (MacBeth Values) test method described herein), radiopaque, durability, good polishing Good physical properties including properties, abrasive holding and wear properties, and mechanical strengths such as flexural strength and adhesion to teeth. In addition, the composition can adhere to both dentin and enamel without the need for primers, etchant or preconditioner. In addition, the present invention allows for easy mixing and convenient dispersing operations with the formation of a paste-paste composition.

Other features and advantages of the invention will be apparent from the following detailed description and claims.

Justice

"Hardenable" means that the composition can be cured or solidified, for example by heating, chemical cross-linking, radiation-induced polymerization or crosslinking.

"Filler" means a particulate material suitable for use in the oral environment. The average particle size of the dental filler is generally up to 100 μm.

"Nano zirconia filler" means a filler comprising zirconia nanoparticles. Typically, nanozirconia fillers comprise non-pyrogenic nanoparticles.

"Paste" means a soft, viscous solid mass dispersed in a liquid.

"Acid-reactive filler" means a filler that reacts chemically in the presence of an acidic component.

"Oxyfluoride" means a substance in which oxygen and fluorine atoms are bonded to the same atom (eg, aluminum in aluminum oxyfluoride). In general, at least 50% of the fluorine atoms in the oxyfluoride material are bonded to atoms containing oxygen atoms.

"Nanostructured" means a material in the form of one or more dimensions on average up to 200 nm (eg, nanosize particles). Accordingly, nanostructured materials include, for example, nanoparticles as defined below; Aggregates of nanoparticles; Materials coated on the particles with an average thickness of 200 nm or less; Materials coated with an average thickness of 200 nm or less on aggregates of particles; Material penetrated into a porous structure having an average pore size of 200 nm or less; And combinations thereof. Examples of the porous structure include porous particles, porous aggregates of particles, porous coating agents, and combinations thereof.

As used herein, "nanoparticle" is used synonymously with "nano sized particles" and refers to particles having an average particle size of 200 nm or less. As used herein for spherical particles, “size” refers to the diameter of the particles. As used herein for non-spherical particles, the “size” refers to the longest dimension of the particles.

"Nanocluster" refers to nanoparticle aggregates that are attracted together, ie attracting each other with relatively weak intermolecular forces that cause aggregation. Typically, the average size of the nanoclusters is 10 μm or less.

The term "ethylenically unsaturated compound having acid functionality" is meant to include monomers, oligomers and polymers having ethylenically unsaturated and acid and / or acid-precursor functionality. Acid-precursor functionalities include, for example, anhydrides, acid halides and pyrophosphates.

“Dental compositions and dental articles” include orthodontic compositions (eg, orthodontic adhesives) and orthodontic devices (eg, orthodontic devices such as retainers, night bites) night guard, bracket, buccal tube, band, cleat, button, lingual retainer, bite opener, positioner And the like).

<Detailed Description of the Invention>

The present invention relates to dental (including orthodontic) compositions, in particular ionomer compositions, such as glass ionomer compositions, containing at least one nanozirconia filler. Such hardenable compositions further comprise polyacids, acid-reactive fillers, optional polymerizable components and water. Incorporating one or more nanozirconia fillers into the composition provides improved properties, including improved aesthetics (eg, low visual opacity), polishing retention, and radiopacity compared to previously known glass ionomer compositions.

Polymerizable Ingredients

As mentioned above, the hardenable dental compositions of the present invention optionally comprise a polymerizable component. The polymerizable component can be an ethylenically unsaturated compound, optionally with or without acid functionality.

The polymerizable component of the present invention may be part of a hardenable resin. Such resins are generally thermosetting materials that can be hardened to form polymeric networks, for example acrylate-functional materials, methacrylate-functional materials, epoxy-functional materials, vinyl-functional materials and And mixtures thereof. Typically, hardenable resins are prepared from one or more matrix-forming oligomers, monomers, polymers or mixtures thereof.

In certain embodiments wherein the dental compositions disclosed herein are dental composites, polymerizable materials suitable for use include sufficient strength, hydrolytic stability, and nontoxic hardenable organic materials suitable for use in the oral environment. Examples of such materials include acrylates, methacrylates, urethanes, carbamoylisocyanurates, epoxies, and mixtures and derivatives thereof.

One class of preferred hardenable materials includes materials comprising polymerizable components having free radically active functional groups. Examples of such materials include monomers having at least one ethylenically unsaturated group, oligomers having at least one ethylenically unsaturated group, polymers having at least one ethylenically unsaturated group, and combinations thereof.

In the class of hardenable resins having free radically active functional groups, polymerizable components suitable for use in the present invention may contain one or more ethylenically unsaturated bonds for addition polymerization. Such free radical ethylenically unsaturated compounds are, for example, mono-, di- or poly- (meth) acrylates (ie acrylates and methacrylates) such as methyl (meth) acrylates, ethyl acrylates, iso Propyl 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-acryloxy)]-p-ethoxyphenyldimethylmethane, bis [1- (3- Methacrylate-2-hydroxyethyl)] - p- propoxyphenyl dimethyl methane, ethoxylated bisphenol A di (meth) acrylate and tris-hydroxy-ethyl-isocyanurate trimethacrylate; (Meth) acrylamides (ie acrylamide and methacrylamide) such as (meth) acrylamide, methylene bis- (meth) acrylamide and daacetone (meth) acrylamide; Urethane (meth) acrylates; Bis- (meth) acrylates of polyethylene glycol (preferably molecular weight 200-500); Copolymerizable mixtures of acrylated monomers as described in US Pat. No. 4,652,274 to Boettcher et al .; Acrylated oligomers as described in US Pat. No. 4,642,126 (Zador et al.); And vinyl compounds such as styrene, diallyl phthalate, divinyl succinate, divinyl adipate and divinyl phthalate. Other suitable free radically polymerizable compounds include, for example, WO-00 / 38619 (Guggenberger et al.), WO-01 / 92271 (Weinmann et al.), WO-01 / 07444 (Guggenberger et al. ), Siloxane-functional (meth) acrylates disclosed in WO-00 / 42092 (Guggenberger et al.), And for example, US Pat. No. 5,076,844 (Fock et al.), US 4,356,296 (Griffith et al. Fluoropolymer-functionality disclosed in EP-0 373 384 (Wagenknecht et al.), EP-0 201 031 (Reiners et al.) And EP-0 201 778 (Reiners et al.). (Meth) acrylate. If desired, mixtures of two or more free radically polymerizable compounds can be used.

The polymerizable component may also contain hydroxyl groups and free radical active functional 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- or di- (meth) acrylates; Trimethylolpropane mono- or di- (meth) acrylate; Pentaerythritol mono-, di- and tri- (meth) acrylates; Sorbitol mono-, di-, tri-, tetra- or penta- (meth) acrylates; And 2,2-bis [4- (2-hydroxy-3-methacryloxypropoxy) phenyl] propane (bisGMA). Suitable ethylenically unsaturated compounds are also commercially available from various sources, such as Sigma-Aldrich (St. Louis, MO). If desired, mixtures of ethylenically unsaturated compounds can be used.

mountain Sensuality  Polymerizable component having

When present, polymerizable components include ethylenically unsaturated compounds, optionally having acid functionality. Preferably, the acid functionality includes oxyacids (ie, oxygen-containing acids) of carbon, sulfur, phosphorus or boron.

Such compounds include, for example, α, β-unsaturated acidic compounds such as glycerol phosphate monomethacrylate, glycerol phosphate dimethacrylate, hydroxyethyl methacrylate phosphate, citric acid di- or tri-methacrylate, poly (Meth) acrylated oligomaleic acid, poly (meth) acrylated polymaleic acid, poly (meth) acrylated poly (meth) acrylic acid, poly (meth) acrylated polycarboxyl-polyphosphonic acid, poly (meth) acrylated polychlorophosphoric acid, Poly (meth) acrylated polysulfonic acid, poly (meth) acrylated polyboric acid, and the like, and the like, and may be used as a component in a hardenable resin system.

Some of these compounds are obtained, for example, as reaction products of isocyanatoalkyl (meth) acrylates and carboxylic acids. Additional compounds of this type having both acid-functional and ethylenically unsaturated components are described in US Pat. No. 4,872,936 to Engelbrecht and 5,130,347 to Mitra. Various such compounds can be used containing both ethylenically unsaturated residues and acid residues. If desired, mixtures of these compounds can be used.

Further ethylenically unsaturated compounds having acid functionality are, for example, U.S.S.N. Polymerizable bisphosphonic acids disclosed in 10 / 729,497; AA: ITA: IEM (e.g., as described in Example 11 of US Pat. No. 5,130,347 to Mitra), the reaction of an AA: ITA copolymer with sufficient 2-isocyanatoethyl methacrylate Copolymers of acrylic acid: itaconic acid with pendant methacrylate, wherein a portion of the acid groups are converted to pendant methacrylate groups; And US Pat. No. 4,259,075 (Yamauchi et al.), 4,499,251 (Omura et al.), 4,537,940 (Omura et al.), 4,539,382 (Omura et al.), 5,530,038 (Yamamoto et al., 6,458,868 (Okada et al.), And European Patent Application Publication No. 712,622 (Tokuyama Corp.) and 1,051,961 (Kuraray Co., Ltd.). Can be.

When an ethylenically unsaturated compound having acid functionality is present, the composition of the present invention typically contains at least 1%, more typically 3%, by weight of the ethylenically unsaturated compound having acid functionality, based on the total amount of the unfilled composition. % Or more, most typically 5% by weight or more. Typically, the compositions of the present invention comprise up to 50 wt%, more typically up to 40 wt%, most typically up to 30 wt% of an ethylenically unsaturated compound having acid functionality based on the total amount of unfilled composition.

Some or complete hardening of the composition can be carried out via acid-reactive filler / polyacid reactions (ie, acid / base reactions). In certain embodiments, the composition also contains a photoinitiator system that initiates polymerization (or hardening) of the composition upon irradiation with actinic radiation. Such photopolymerizable compositions may be free radically polymerizable.

freedom Radical  Initiation system

For free radical polymerization (eg, hardening), the initiating system can be selected from the system initiating the polymerization via a spinning, thermal or redox / self-curing chemical reaction. Classes of initiators capable of initiating the polymerization of free radically active functional groups include free radical-generating photoinitiators, optionally together with photosensitizers or accelerators. Such initiators can generate free radicals for further polymerization upon exposure to light energy, which typically has a wavelength of 200 to 800 nm.

Suitable photoinitiators (ie, photoinitiator systems comprising at least one compound) for polymerizing free radical photopolymerizable compositions include bicomponent and tricomponent systems. Typical three-component photoinitiators include iodonium salts, photosensitizers and electron donor compounds as described in US Pat. No. 5,545,676 (Palazzotto et al.). Preferred iodonium salts are the diaryl iodonium salts, for example diphenyliodonium chloride, diphenyliodonium hexafluorophosphate, diphenyliodonium tetrafluoroborate and tolyl cumyliodonium tetrakis (Pentafluorophenyl) borate is mentioned. Preferred photosensitizers are monoketones and diketones that absorb some light in the range of about 400 nm to 520 nm (preferably between 450 nm and 500 nm). More preferred compounds are alpha diketones that absorb some light in the range of about 400 nm to 520 nm (preferably between 450 nm and 500 nm). Preferred compounds are camphorquinone, benzyl, furyl, 3,3,6,6-tetramethylcyclohexanedione, phenanthraquinone, 1-phenyl-1,2-propanedione and other 1-aryl-2-alkyl-1 , 2-ethanedione and cyclic alpha diketone. Camphorquinone is most preferred. Preferred electron donating compounds include substituted amines such as ethyl dimethylaminobenzoate. Other suitable three-component photoinitiators useful for photopolymerizing cationic polymerizable resins are described, for example, in US Patent Publication 2003/0166737 (Dede et al.).

Other photoinitiators suitable for polymerizing free radical photopolymerizable compositions include a class of phosphine oxides that typically have a functional wavelength range of 380 nm to 1200 nm. Preferred phosphine oxide free radical initiators having a functional wavelength range of 380 nm to 450 nm are acyl and bisacyl phosphine oxides such as US Pat. No. 4,298,738 (Lechtken et al., US Pat. No. 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 European Application No. 0 173 567 A2 (Ying).

Commercially available phosphine oxide photoinitiators capable of free-radical initiation upon irradiation in the wavelength range greater than 380 nm to 450 nm include, for example, Ciba Specialty Chemicals (Taritown, NY). Bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide, sold as IRGACURE 819; Bis (2,6-dimethoxybenzoyl)-(2,4,4-trimethylpentyl) phosphine oxide, sold under the trade name CGI 403 from Ciba Specialty Chemicals; Bis (2,6-dimethoxybenzoyl) -2,4,4-trimethylpentyl phosphine oxide and 2-hydroxy-2-methyl-1-phenylpropane commercially available from Ciba Specialty Chemicals under the tradename Irgacure 1700. 25:75 mixture of 1-one; Bis (2,4,6-trimethylbenzoyl) phenyl phosphine oxide and 2-hydroxy-2-methyl-1-phenylpropan-1-one sold by Ciba Specialty Chemicals under the trade name DAROCUR 4265. 1: 1 mixture of; And ethyl 2,4,6-trimethylbenzylphenyl phosphinate sold by BASF Corp., Charlotte, NC, under the trade name LUCIRIN LR8893X.

Typically, the phosphine oxide initiator is present in the photopolymerizable composition in an amount of from 0.1% to 5% by weight based on the catalyst effective amount, such as the total amount of the composition.

Tertiary amine reducing agents can be used in combination with acylphosphine oxides. Examples of tertiary amines useful in the present invention include ethyl 4- (N, N-dimethylamino) benzoate and N, N-dimethylaminoethyl methacrylate. If an amine reducing agent is present in the photopolymerizable composition, it is present in an amount of 0.1% to 5% by weight based on the total amount of the composition. Useful amounts of other initiators are known to those skilled in the art.

Another free-radical initiator system that can be used differently as the dental material of the present invention includes a class of ionic dye-counterion complexes comprising borate anions and complementary cationic dyes. Borate photoinitiators are described, for example, in US Pat. Nos. 4,772,530 (Gottschalk et al.), 4,954,414 (Adair et al.), 4,874,450 (Gottschalk), 5,055,372 (Shanklin et al.) And No. 5,057,393 to Shanklin et al.

The hardenable resins of the present invention include redox curing systems comprising a polymerizable component (eg, an ethylenically unsaturated polymerizable component) and an oxidation-reducing agent including an oxidizing agent and a reducing agent. Suitable polymerizable components and redox agents useful in the present invention are described in US Patent Application Publication Nos. 2003/0166740 to Mitra et al. And 2003/0195273 to Mitra et al.

The reducing and oxidizing agents react with or cooperate with each other to produce free-radicals that can initiate the polymerization of the resin system (eg, ethylenically unsaturated components). Since this type of curing is a dark reaction, it does not matter whether light is present or not and can be performed without light. The reducing and oxidizing agents are preferably sufficiently stable at room temperature and free of undesirable pigmentation allowing for storage and use in typical dental conditions. It must be sufficiently miscible (and preferably water soluble) with the resin system to readily dissolve in the other components of the polymerizable composition.

Useful reducing agents include ascorbic acid, ascorbic acid derivatives and metal complexed ascorbic acid compounds, as described, for example, in US Pat. No. 5,501,727 (Wang et al.); Amines, especially tertiary amines such as 4-tert-butyl dimethylaniline; Aromatic sulfinates, such as the p-toluenesulfonic acid salts and the benzenesulfinic acid salts; Thioureas such as 1-ethyl-2-thiourea, tetraethyl thiourea, tetramethyl thiourea, 1,1-dibutyl thiourea and 1,3-dibutyl thiourea; And mixtures thereof. Other secondary reducing agents include cobalt (II) chloride, ferrous chloride, ferrous sulfate, hydrazine, hydroxylamine (depending on the choice of oxidizing agent), salts of dithionite or sulfite anions, and their Combinations. Preferred reducing agents are amines.

Suitable oxidants will also be known to those skilled in the art and include, for example, persulfate and salts thereof, such as sodium, potassium, ammonium, cesium and alkyl ammonium salts. Further oxidizing agents include, for example, peroxides such as benzoyl peroxide, hydroperoxides such as cumyl hydroperoxide, t-butyl hydroperoxide and amyl hydroperoxide, and also transition metal salts such as cobalt (II) chloride, chlorides Ferrous, cerium (IV) sulfate, perboric acid and salts thereof, permanganic acid and salts thereof, superphosphoric acid and salts thereof, and combinations thereof.

It may be desirable to use one or more oxidizing agents or one or more reducing agents. Small amounts of transition metal compounds can be added to accelerate the rate of redox cure. In some embodiments, it may be desirable to improve the stability of the hardenable composition, including secondary ionic salts, as described, for example, in US Patent Publication 2003/0195273 (Mitra et al.).

The reducing and oxidizing agents are present in sufficient amounts to allow for a suitable free-radical reaction rate. This can be assessed by summing all the components of the hardenable composition except the filler and observing whether a hardened mass is obtained.

Preferably, the reducing agent is present in an amount of at least 0.01% by weight, more preferably at least 0.10% by weight, based on the total amount (including water) of the components of the hardenable composition. Preferably, the reducing agent is present in an amount of up to 10% by weight, more preferably up to 5% by weight, based on the total amount (including water) of the components of the polymerizable composition.

Preferably, the oxidant is present in an amount of at least 0.01% by weight, more preferably at least 0.10% by weight, based on the total amount of components of the polymerizable composition (including water). Preferably, the oxidant is present in an amount of up to 10% by weight, more preferably up to 5% by weight, based on the total amount of components of the hardenable composition (including water).

Reducing or oxidizing agents can be microencapsulated, for example, as described in US Pat. No. 5,154,762 to Mitra et al. This will generally improve the storage-stability of the polymerizable composition and make it possible to pack the reducing and oxidizing agents together if necessary. For example, through the appropriate choice of encapsulating agent, the oxidizing agent and reducing agent can be combined with the acid-functional component and any filler to leave it in a storage-stable state. In addition, through the appropriate choice of water-insoluble encapsulants, the reducing and oxidizing agents may be combined with the FAS glass and water, leaving the storage-stable state.

Alternatively, heating may initiate the hardening or polymerization of the free radical activating group. Examples of suitable heat sources for the dental material of the present invention include conduction, convection and radiation. The heat source should be capable of generating temperatures of at least 40 ° C. and at most 150 ° C. under constant or elevated pressure. The method is preferred for initiating material polymerization that occurs outside of the oral environment.

In addition, another class of initiators capable of initiating the polymerization of free radical activating functional groups in the hardenable resin are those that include free radical-generating thermal initiators. Examples include peroxides (eg benzoyl peroxide and lauryl peroxide) and azo compounds (eg 2,2-azobis-isobutyronitrile (AIBN)).

The photoinitiator compound is preferably provided in the dental composition disclosed herein in an amount effective to initiate or enhance the rate of curing or hardening of the resin system. Useful photopolymerizable compositions are prepared by simply mixing the components under harmless light conditions as described above. If desired, suitable inert solvents can be used in the preparation of the mixture. Any solvent that does not explicitly react with the components of the composition of the present invention can be used. Examples of suitable solvents include acetone, dichloromethane and acetonitrile.

Polyacid

The compositions of the present invention comprise one or more polyacids which may be non-curable or non-polymerizable polyacids, or curable or polymerizable polyacids (eg, resin-modified polyacids). Typically, polyacids are polymers having a plurality of acidic repeat units and a plurality of polymerizable groups. In other embodiments, the polyacid may be substantially free of polymerizable groups. The polyacid does not need to be water soluble as a whole, but must be at least sufficiently water-miscible so that no significant precipitation occurs when combined with other aqueous components. Suitable polyacids are listed in US Pat. No. 4,209,434 (Wilson et al.) Column 2, line 62 to column 3, line 6. The polyacid should have a molecular weight sufficient to provide good shelf life, handleability and miscibility. Typical weight average molecular weights are from 5,000 to 100,000 as measured against polystyrene standards using gel permeation chromatography.

In one embodiment, the polyacid is a curable or polymerizable resin. That is, it contains one or more ethylenically unsaturated groups. Suitable ethylenically unsaturated polyacids are described, for example, in US Pat. Nos. 4,872,936 to Engelbrecht Nos. 3 and 4, and EP 323 120 B1 (Mitra), page 3, lines 55 to 5, line 8 have. Typically, the number of acidic and ethylenically unsaturated groups is adjusted to provide the dental composition with well balanced properties. Preference is given to replacing polyacids having an acidic group of 10% to 70% with an ethylenically unsaturated group.

In other embodiments, the polyacid is hardenable, for example in the presence of an acid-reactive filler and water, but does not contain ethylenically unsaturated groups. That is, oligomers or polymers of unsaturated acids. Typically, the unsaturated acid is an oxyacid (ie, an oxygen containing acid) of carbon, sulfur, phosphorus or boron. More typically, it is an oxyacid of carbon. Such polyacids include, for example, homopolymers and copolymers of polyalkenic acids such as unsaturated mono-, di- or tricarboxylic acids. Polyalkenic acids are unsaturated aliphatic carboxylic acids, for example acrylic acid, 2-chloroacrylic acid, 3-chloroacrylic acid, 2-bromoacrylic acid, 3-bromoacrylic acid, methacrylic acid, itaconic acid, maleic acid, glutamic acid, It can be prepared by homopolymerization and copolymerization of aconic acid, citraconic acid, mesaconic acid, fumaric acid and tiglic acid. Suitable monomers that can be copolymerized with unsaturated aliphatic carboxylic acids include, for example, unsaturated aliphatic compounds such as acrylamide, acrylonitrile, vinyl chloride, allyl chloride, vinyl acetate and 2-hydroxyethyl methacrylate. have. If desired, terpolymers and higher polymers can be used. Particular preference is given to homopolymers and copolymers of acrylic acid. The polyalkenic acid should be substantially free of unpolymerized monomers.

The amount of polyacid should be sufficient to react with the acid-reactive filler and to provide the ionomer composition with the desired curing properties. Typically, the polyacids represent at least 1 wt%, more typically at least 3 wt%, most typically at least 5 wt%, based on the total amount of the unfilled composition. Typically, the polyacids represent up to 90 weight percent, more typically up to 60 weight percent, most typically up to 30 weight percent, based on the total amount of the unfilled composition.

Acid-Reactive Fillers

Suitable acid-reactive fillers include metal oxides, glass and metal salts. Typical metal oxides include barium oxide, calcium oxide, magnesium oxide and zinc oxide. Typical glasses include borate glasses, phosphate glasses and fluoroaluminosilicate (“FAS”) glasses. FAS glass is particularly preferred. FAS glasses typically contain sufficiently elutable cations such that upon mixing of the glass with the hardenable composition components a hardened dental composition can be formed. The glass also typically contains sufficiently elutable fluoride ions such that the hardened composition can have caries development inhibiting properties. Glass can be made from a melt containing fluoride, alumina and other glass-forming components using techniques known to those skilled in the art of FAS glass making. FAS glasses are typically in the form of particles that are sufficiently finely divided so that they can be conveniently mixed with other cement components and perform well when the resulting mixture is used in the oral cavity.

In general, the average particle size (typically diameter) for FAS glass is about 12 μm or less, typically 10 μm or less, more typically about 5 μm or less, as measured using a precipitation analyzer, for example. Suitable FAS glasses will be known to those skilled in the art and are available from a variety of sources and are currently available glass ionomer cements such as VITREMER, VITREBOND, RELY X LUTING cement, RELY X Routing Plus Cement, PHOTAC-FIL QUICK, KETAC MOLAR and KETAC-FIL PLUS (3M ESPE Dental Products; 3M ESPE Dental Products; Minnesota, USA) St. Paul), FUJI II LC and Fuji IX (GC Dental Industrial Corp., Tokyo, Japan) and CHEMFIL Superior (Dentsply International, Pennsylvania, USA) Many cements are commercially available as main yoke materials, although filler mixtures can be used if desired.

FAS glass can optionally be surface treated. Suitable surface treatments include, but are not limited to, acid washing (eg, treatment with phosphoric acid), treatment with phosphates, treatment with chelating agents such as tartaric acid, silanes, or acidic or basic silanol solutions. Do not. Preferably, the pH of the treated solution or treated glass is adjusted to neutral or near-neutral, which can increase the storage stability of the hardenable composition.

In another embodiment, the acid-reactive filler comprises a non-fused oxyfluoride material. Oxyfluoride materials can include trivalent metals, oxygen, fluorine and alkaline earth metals. Preferably, the trivalent metal is aluminum, lanthanum or combinations thereof. More preferably, the trivalent metal is aluminum. Preferably, the alkaline earth metal is strontium, calcium, barium or combinations thereof. In some embodiments of the invention, the oxyfluoride material adds silicon and / or heavy metals (eg, zirconium, lanthanum, niobium, yttrium or tantalum), more particularly oxides, fluorides and / or oxyfluorides thereof. It can be included as.

In some embodiments of the invention, at least some of the oxyfluoride material is nanostructured. Such nanostructured materials include, for example, oxyfluoride materials in the form of nanoparticles, coatings on particles, coatings on particle aggregates, penetrants in porous structures, and combinations thereof. Preferably at least 90% by weight, more preferably at least 95% by weight and most preferably at least 98% by weight of the oxyfluoride material are nanostructures.

A description of suitable oxyfluoride materials and their use in dental compositions is described in US patent application "Acid Reactive Dental Fillers, Compositions, and Methods," filed May 17, 2004. (Attorney docket no. 58618US002).

The amount of acid-reactive filler should be sufficient to provide an ionomer composition having desirable mixing and handling properties prior to hardening and having good physical and visual properties after hardening. Generally, the reactive filler appears to be less than about 85% of the total amount of the composition. Typically, the acid-reactive filler represents at least 10% by weight, more typically at least 20% by weight, based on the total amount of the composition. Typically, the acid-reactive filler represents 75 wt% or less, more typically 50 wt% or less, based on the total amount of the composition.

Nano Zirconia  filling

The ionomer compositions of the invention are formulated with nanozirconia fillers. Such fillers provide a radiopaque composition, allowing the preparation of radiopaque and optically translucent ionomer compositions while using less than the amount of FAS glass previously required. This allows the ionomer composition to be produced, for example, in a two-part paste-paste system.

Zirconia is a very radiopaque metal oxide with X-ray scattering and filler strengthening properties. Nanozirconia is a nanosized crystalline ZrO ₂ particle. The average particle size of such nanozirconia fillers is typically 100 nm or less, more typically 75 nm or less, even more typically 50 nm or less, most typically 20 nm or less. The average particle size of such nanozirconia fillers is typically 2 nm or less, more typically 5 nm or less. The first particles of the nanozirconia filler may or may not be aggregated. In certain embodiments, zirconia nanoparticles typically have an aggregate size of 150 nm or less, more typically 100 nm or less. Very small overall particle size reduces light scattering with good dispersion and provides an optically translucent material.

In addition, the zirconia nanoparticles can be surface modified and preferably dispersed in the dental composition in a nanoaggregated state. Acidic functionalities such as carboxylic acid and phosphonic acid are readily adsorbed on the surface of the ZrO ₂ particles. This type of molecular adsorption is in many cases a very good means of surface modification. For example, carboxylic acid combinations can be used to provide very good dispersibility and reactivity in composite formulations. However, for use in ionomer compositions, surface modification is required that not only disperses the particles but also passivates the surface for polyacid adsorption. Surface modification with silane or a combination of silane and phosphonic acid may passivate the surface and incorporate nanozirconia into the ionomer formulation. As illustrated in the examples included herein, ionomer compositions containing surface-modified nanozirconia fillers are formulated into a paste / paste system having radiopaque, visual opacity and good physical properties.

The amount of nanozirconia filler should be sufficient to provide an ionomer composition having desirable mixing and handling properties prior to hardening and having good physical and optical properties after mixing. Typically, the nanozirconia fillers represent at least 0.1% by weight, more typically at least 10% by weight and most typically at least 20% by weight, based on the total amount of the composition. Typically, nanozirconia fillers represent up to 80 weight percent, more typically up to 70 weight percent, most typically up to 60 weight percent, based on the total amount of the composition.

Other fillings

In addition to the acid-reactive filler and nanozirconia filler components, the compositions of the present invention may also optionally include one or more other fillers. Such fillers may be selected from one or more of a variety of materials suitable for use in dental and / or orthodontic compositions.

The other filler may be an inorganic material. It may also be a crosslinked organic material insoluble in the resin component of the composition, optionally filled with an inorganic filler. Fillers should always be nontoxic and suitable for oral use. The filler may be radiopaque or radiopaque. Typically, the filler is substantially water insoluble.

Examples of suitable inorganic fillers include quartz; Nitrides (eg, silicon nitride); Glass derived from, for example, Zr, Sr, Ce, Sb, Sn, Ba, Zn and Al; feldspar; Borosilicate glass; kaoline; talc; Titania; Low modulus hardness fillers as described in US Pat. No. 4,695,251 (Randklev); And trade names Aerosil, including "OX 50", "130", "150" and "200" silicas from silica particles (eg, Degussa AG, Hanau, Germany), and cabot Naturally occurring or synthetic materials, including, but not limited to, Cabot Corp. (ultrafine pyrogenic silica, such as CAB-O-SIL M5 silica from Tuscola, Ill.). Examples of suitable organic filler particles include filled or unfilled ground polycarbonates, polyepoxides and the like. Other fillers, including other nanofillers that may be used in the compositions of the present invention, are described in US patent application "Dental Compositions Containing Nanofillers and Related Methods," filed May 17, 2004. Dock No. 59610US002) and “Use of Nanoparticles to Adjust Refractive Index of Dental Compositions” (Lawyer Dock No. 59611US002).

Suitable non-acid-reactive filler particles are quartz, ultrafine silica and non-glassy microparticles of the type described in US Pat. No. 4,503,169 (Randklev). As well as combination fillers made of organic and inorganic materials, mixtures of these non-acid-reactive fillers are also contemplated.

In addition, the surface of the filler particles can be treated with a binder to improve the dispersion of the filler in the resin and the bonding between the filler and the resin. Suitable fillers used include gamma-methacryloxypropyltrimethoxysilane, gamma-mercaptopropyltriethoxysilane, gamma-amino propyltrimethoxysilane, and the like. Examples of useful silane coupling agents are sold as SILQUEST A-174 and Silquest A-1230 from Crompton Corporation (Nogatuk, Connecticut, USA).

In some embodiments of the invention, including other fillers (eg, dental restorative compositions), the composition is at least 1% by weight, more preferably at least 2% by weight, most preferably 5, based on the total amount of the composition Other fillers by weight or greater. In such embodiments, the compositions of the present invention preferably comprise up to 40% by weight, more preferably up to 20% by weight and most preferably up to 15% by weight of other fillers, based on the total amount of the composition.

water

The composition of the present invention contains water. The water may be distilled water, deionized water or tap water. Typically, deionized water is used.

The amount of water should be sufficient to provide sufficient handling and mixing properties, and in particular to allow the movement of ions in the filler-acid reaction. Preferably, water represents at least 2% by weight, more preferably at least 5% by weight of the total amount of the components used to form the composition. Preferably, water represents 90% by weight or less, more preferably 80% by weight or less of the total amount of the components used to form the composition.

Arbitrary additives

Optionally, the hardenable composition may contain a solvent, a cosolvent (eg alcohol) or a diluent. If desired, the hardenable compositions of the present invention contain indicators, dyes, pigments, inhibitors, accelerators, viscosity modifiers, wetting agents, tartaric acid, chelating agents, surfactants, buffers, stabilizers, and other similar ingredients apparent to those skilled in the art. can do. In addition, a medicament or other therapeutic substance may optionally be added to the dental composition. Examples of types often used in dental compositions include sources of fluoride, whitening agents, caries preventive agents (e.g. xylitol), inorganic supplements (e.g. calcium phosphate compounds), enzymes, mouthwashes, anesthetics, coagulants, Acid neutralizers, chemotherapeutic agents, immune response modifiers, thixotropic agents, polyols, anti-inflammatory agents, antibacterial agents, antifungal agents, dry mouth cure agents, desensitizers, and the like, and the like. Combinations of any of the above additives may be used. The choice and amount of these optional additives can be chosen by those skilled in the art to achieve the desired result without undue experimentation.

Preparation and Use of the Composition

The hardenable dental compositions of the present invention can be prepared by combining all of the various components using conventional mixing techniques. As disclosed above, the composition may be partially or fully hardened by the ionic reaction between the acid-reactive filler and the polyacid. Optionally, the composition may be hardened by photoinitiation containing polymerizable components and photoinitiators, or chemical polymerization such as redox curing systems in compositions containing free-radical initiator systems including, for example, oxidizing and reducing agents. Some or all may be hardened. Alternatively, the hardenable composition may contain various initiator systems to be photopolymerizable and chemically polymerizable as well as ionic hardenable compositions.

The hardenable compositions of the present invention can be supplied in a variety of forms including one-part systems and multi-part systems, such as two-part powders / liquids, pastes / liquids, pastes / powders and pastes / pastes systems. Other forms are also possible using multi-part combinations (ie, two-part or more combinations) in the form of each additional powder, liquid, gel or paste. Various components of the composition can be divided into sequesters in the desired manner. However, polyacids, acid-reactive fillers and water are generally not all present in the same moiety, but any two of these may be grouped together in the same moiety in combination with any other ingredients. In addition, in the redox multi-part system, one part typically contains an oxidant and another part typically contains a reducing agent. However, if the components are stored separately, for example via microencapsulation, the reducing and oxidizing agents may be mixed in the same part of the system.

Suitable surface treatment of nanozirconia fillers is necessary to achieve good dispersion in the resin composition, to impart the desired fluidity, aesthetics and strength properties to the composition, and in particular to obtain a stable composition in the presence of acidic components. Silane treatment of zirconia nanoparticles is typically carried out by reaction of a silane coupling agent or a combination of silane coupling agents with zirconia in the form of an aqueous sol. The zirconia sol is typically acidic at pH 2-5, and any cosolvent may be used. The resulting mixture is typically heated at 80 ° C. to 90 ° C. for 3 to 16 hours, although other temperatures and times may be used. After the heating cycle is complete, the solvent may be removed (solvent exchange) in the presence of the resin, or the solvent may be removed and then the isolated solid filler may be dispersed in the resin to incorporate the silane-treated zirconia into the resin system. Optionally, a base such as aqueous ammonia can be added to raise the pH of the sol. Typically, base is added after a heating cycle under acidic conditions. Optionally, base may be added before the heating cycle.

In a preferred embodiment, the zirconia sol is heated with two or more silane coupling agents under acidic conditions (eg, in the presence of 2- [2- (2-methoxyethoxy) ethoxy] acetic acid (MEEAA)). do. After cooling, the mixture is added to diluted aqueous ammonia solution. Other base materials can be used in place of the ammonia solution. The addition of base will generally result in zirconia solid precipitation. The base is believed to facilitate the removal of adhered (eg, adsorbed) acid from the surface of the silane-treated zirconia. Subsequent solid filtration and washing allow for further acid removal. Removal of such acids can be particularly advantageous when zirconia is surface treated with high molecular weight nonvolatile acids such as MEEAA. If the high molecular weight acid is not removed after silane treatment, significant amounts of residual acid can be incorporated into the final composition, causing undesirable composition properties and reduced composition d stability. After filtration, the silane-treated nanozirconia filler can be redispersed in a solvent and subsequently incorporated into the resin via solvent exchange, or typically the solid is dried to a powder and redispersed in the resin.

Nanozirconia fillers may be surface treated with a combination of silane coupling agents to provide the composition with desirable fluidity and physical properties (eg, visual opacity). In particular, the use of typical reactive silanes such as Silquist A-174 in combination with hydrophilic silanes such as SILQUIST A-1230 is in some embodiments for use in ionomer compositions of the present invention comprising a relatively polar resin system. It can be advantageous for surface-treated nanozirconia fillers.

In some embodiments, a two-part dental composition of the present invention may be provided in a dual container syringe having a first container and a second container, wherein part A is in the first container and part B is in the second container. do. In other embodiments, the two-part dental composition of the present invention may be provided in unit-dose capsules. In some embodiments, each portion of a multi-part dental system can be mixed together using a static mixer. The components of the hardenable composition may be included in a kit to package the contents of the composition for storage of the components if necessary.

When used in a dental composition, the components of the hardenable composition can be mixed and clinically applied using conventional techniques. Photopolymerizers are generally required for the initiation of photopolymerizable compositions. The composition may be in the form of a composite or restoration that adheres very well to dentin and / or enamel. Optionally, a surface conditioner or primer layer can be used for the dental tissue in which the hardenable composition is used. For example, compositions containing FAS glass or other fluoride-glass materials can also liberate fluoride for a very long time. Some embodiments of the present invention can be cured in large quantities without the use of light or other external curing energy, require no pretreatment, have improved physical properties, including improved flexural strength, and many fluorides for caries development inhibiting effect. It is possible to provide a glass ionomer cement or adhesive in which is free.

The hardenable dental compositions of the present invention are particularly adapted for use in the form of various dental materials. It can be used in prosthetic cements and is typically a filled composition (preferably containing more than about 25 weight percent up to about 60 weight percent). It can be used in restorations and includes composites, such as filling materials, which are typically filled compositions (preferably containing more than about 10 weight percent up to about 85 weight percent) that polymerize after exposure adjacent to teeth. It can be used for prostheses (eg, crowns, dentures, verniers, inlays, onlays, etc.) that are molded and hardened for final use prior to exposure to the teeth. Such preformed articles can be crushed or shaped into a customer-customized form by a dentist or other user. The hardenable dental composition may be any of a variety of materials, but preferably the composition is not a surface pretreated material (eg, etchant, primer, binder). Rather, preferably, the hardenable dental composition is a restoration (eg, a composite, a filler material or a prosthesis), a cement, a sealant, a coating or an orthodontic adhesive.

Features and advantages of the invention are further described in the following examples, but are not intended to be limiting. The specific materials and amounts thereof referred to in the examples below, as well as the conditions and details, should not be construed as excessively limiting the invention. Unless indicated otherwise, all parts and fractions are by weight, all water is deionized water, and all molecular weights are average molecular weight.

Test Methods

Compressive strength (CS) test method

First, the mixed paste-paste test sample was injected into a glass tube with an inner diameter of 4 mm to estimate the compressive strength. The ends of the glass tubes were closed with silicone stoppers. A pressure of 0.275 MPa was applied to the filled tube for 5 minutes, irradiated with XL 1500 light polymerizer (3M Company) for 60 seconds, and KULZER UniXS, Kulzer, Inc. (Germany) )) Placed in light box for 90 seconds. Five such cured samples were cut to 8 mm length and placed in water at 37 ° C. for 1 day. Compressive strength was measured according to ISO standard 7489 using an INSTRON universal tester (Instron Corp., Canton, Mass.) Operating at a crosshead speed of 1 mm per minute. The average of five replicates was recorded as a result.

Indirect tensile strength ( DTS ) Test Methods

Indirect tensile strength was measured using the CS method described above, but a sample cut to 2 mm length was used. The average of seven replicates was reported as a result.

Visual Opacity (Macbeth Value) Test Method

Disc samples (1 mm thick by 15 mm diameter) were exposed to illumination from a VISILUX 2 light polymerizer (3M, St. Paul, MN) for 60 seconds on each side of the disc 6 mm apart. And hardened. Direct light of hardened samples by measuring the transmission of light through the thickness of the disc using Macbeth transmission densitometer model TD-903 (MacBeth, Newburgh, NY) equipped with a visible light filter Permeability was measured. Smaller Macbeth values indicate lower visual opacity and higher translucency of the material. The value reported is the average of three measurements.

radiation Opacity  Test Methods

Discoid (thickness 1 mm x diameter 15 mm) paste test samples were cured by exposure to illumination of a Visilux 2 light polymerizer (3M) for 60 seconds on each side of the disc 6 mm apart. The radiopacity of the cured sample was then estimated as follows.

To estimate the radiopacity, the following ISO-Test Method 4049 (1988) was used. In particular, using a Gendex GX-770 dental X-ray (Milwaukee, WI) device, radioactive composite samples cured for 0.73 seconds at 7 mA and 70 kV maximum voltage at a distance of about 400 mm Exposed. During the exposure the aluminum stair wedges were placed next to the cured disc on the X-ray film. X-ray negatives were developed using an Air Techniques Peri-Pro automatic film developer (Higgsville, NY). A Macbeth densitometer was used to compare the optical density of the sample discs with the optical density of the aluminum stair wedges. The recorded value of optical density (ie radiopacity) is the average of three measurements.

Abbreviations, descriptions and suppliers of materials Abbreviation Description and source of material HEMA 2-hydroxyethyl methacrylate (Sigma-Aldrich) Bis GMA 2,2-bis [4- (2-hydroxy-3-methacryloyloxy-propoxy) phenyl] propane; CAS Number 1565-94-2 PEGDMA-400 Polyethylene glycol dimethacrylate (Sartomer 603; MW approximately 570; Sartomer, Exton, Pa.) Resin A Mixture of PEGDMA-400 (62 wt%) and HEMA (38 wt%) AA: ITA Copolymers prepared from acrylic acid: itaconic acid with a molar ratio of 4: 1 according to Example 3 of US Pat. No. 5,130,347 to Mitra, MW (mean) = 106,000; Polydispersity ρ = 4.64 IEM 2-isocyanatoethyl methacrylate (Sigma-Aldrich) VBCP A polymer prepared by reacting the copolymer with an IEM sufficient to convert 16 mole percent acid groups of the AA: ITA copolymer into pendant methacrylate groups, according to the preparation of the dry polymer of Example 11 of US Pat. No. 5,130,347. GDMA Glycerol Dimethacrylate (Rhom and Tech, Inc., Malden, Mass.) Kayamer PM-2 Bis (methacryloxyethyl) phosphate (Nippon Kayaku, Japan) Ebecryl 1830 Polyester hexaacrylate resin (UCB-Radcure Specialties, Brussels, Belgium) BHT Butylated Hydroxytoluene (Sigma-Aldrich) DPIPF6 Diphenyliodonium hexafluorophosphate (Johnson Matthey, Alpha Aesar Division, Ward Hill, NJ) CPQ Camphorquinone (Sigma-Aldrich) MEEAA 2- [2- (2-methoxyethoxy) ethoxy] acetic acid (Sigma-Aldrich) Zirconia Sol An aqueous zirconia sol containing 23% solids prepared as described in US Pat. No. 5,037,579 to Matchette. The average first particle size was measured at 5 nm based on the microcrystalline particle size and crystal form content test method described in US Pat. No. 6,387,981 (Zhang et al.), And the average aggregate particle size was US Pat. No. 6,387,981 (Zhang et al.). Measured from 50 to 60 nm based on the photon correlation spectroscopy test method described in. Seal Quest A-174 Γ-methacryloxypropyltrimethoxysilane used for silane treatment of fillers (Crompton Corporation, Nogatuk, CT) Seal Quest A-1230 PEG silane (Chromphton) used for silane treatment of fillers Aerosil (AEROSIL) R812S Fumed Silica Fillers (Degussa, Germany) Filler A (FAS Glass) Schott glass (product number G 018-117; average particle size 1.0 μm; Schott Electronic Packaging, GmbH, Landshut, Germany) The filler is described in US Patent Publication 2003/0166740 (Mitra). silane-treated as described for filler FAS VI in et al. Filler E (nano filler) U.S. Patent No. 2003/0181541 (Wu et al.) Prepared silane-treated non-agglomerated nanosize silica particles in the form of dry powders according to the method for Filler A. The average particle size of Filler E was found to be the same as the starting Nalco 2329 silica sol, ie about 75 nm. Filler F (nano filler) Except for using nalco 2327 instead of nalco 2329, silane-treated non-agglomerated nanosize silica particles in the form of dry powders were prepared according to the method for Filler A in US 2003/0181541 (Wu et al.). Prepared. The average particle size of filler F was found to be the same as the starting NALCO 2327 silica sol, ie about 20 nm.  Filler I (Example 1) (Nano zirconia) Silane-treated nano zirconia fillers prepared according to Example 1 described herein Filling material I / resin A (nano zirconia) Semi-transparent paste containing 80% by weight of filler I in resin A (see Example 1) Filler K (Comparative Example 1) (Nano zirconia) Acid-treated nanozirconia fillers prepared according to Comparative Example 1 described herein Filling material K / resin A (nano zirconia) Semitransparent, slightly viscous substance containing 80% by weight of filler K in Resin A (see Comparative Example 1).

Example  One:

Silane -Processed Nano Zirconia  (Filler I)

Zirconia sol (800.0 g; 184 g zirconia) and MEEAA (72.08 g) were charged to a 1 L round bottom flask. Water and acid were removed by rotary evaporation to give a powder (291.36 g) which was further dried in a forced draft oven (90 ° C.) to give a dry powder (282.49 g). Deionized water (DI) (501.0 g) was added to redisperse the powder. The resulting dispersion was charged into a 2 L beaker and then stirred with 1-methoxy-2-propanol (783 g; Sigma-Aldrich), Silquest A-174 (83.7 g) and Silquest A-1230 (56.3 g) Added. The resulting mixture was stirred at room temperature for 30 minutes, then separated into about 1.9 L (2 qt) bottles and sealed. The bottle was heated to 90 ° C. for 4 hours and the contents were concentrated by rotary evaporation to give a liquid concentrate (621 g).

Deionized water (2400 g) and concentrated ammonia / water (80.0 g; 29% NH ₃ ) were charged to a 4 L beaker followed by addition of the liquid concentrate over about 5 minutes to give a white precipitate. The precipitate was recovered by vacuum filtration and washed with deionized water. The wet cake obtained was dispersed in 1-methoxy-2-propanol (661 g) to give a dispersion containing 15.33% by weight of silane-treated nanozirconia. The silane-treated nanozirconia filler was called Filler I (Example 1).

The dispersion (1183 g) was combined with resin A [HEMA (24.06 g) and PEGDMA-400 (39.59 g), and water and alcohol were removed by rotary evaporation to yield 80 weights of silane-treated nanozirconia filler (filler I). A translucent paste containing% was obtained. The first particle size and the aggregate particle size of Filler I were found to be the same as the starting zirconia sol, ie about 5 nm and 50 to 60 nm, respectively.

Comparative example  One:

Acid-treated Nano Zirconia  (Filler K)

Zirconia sol (30.0 g; 9.39 g zirconia) and MEEAA (3.67 g) were charged to a 100 ml round bottom flask. Water was removed by rotary evaporation to give dry powder (8 g), which was called Filler K (Comparative Example 1).

Dry powder (8 g) is combined with resin A [HEMA (0.756 g) and PEGDMA-400 (1.244 g)] and quickly mixed to give a translucent containing about 80% by weight of acid-treated nanozirconia filler (filler K). A somewhat viscous material was obtained. The first particle size and the aggregate particle size of the filler K were found to be the same as the starting zirconia sol, ie about 5 nm and 50 to 60 nm, respectively.

Example  2 to 3 and Comparative example  2 to 4:

Paste A-Paste B Composition

Five first paste compositions (denoted by letter A, such as A1 through A5) were prepared by combining the ingredients listed in Table 1 (expressed in parts by weight). Filler I and Filler K were added to the composition as a mixture in Resin A (about 80% by weight) and reported in the table below based on the weight of dry filler; The resin A component was recorded as part of the HEMA and PEGDMA-400 components.

A second paste composition (indicated by the letter B, as in B1 to B2) was prepared by combining the components listed in Table 2 (in parts by weight).

The first paste was spuntulated with the second paste for 25 seconds to prepare a hardenable composition (Examples 2-3 and Comparative Examples 2-4). The relative and component parts by weight of the paste used in the composition are provided in Table 3 below.

The compressive strength (DS), indirect tensile strength (DTS), visual opacity and radiopacity of the hardenable composition were estimated according to the test methods described herein and the results are reported in Table 4 below.

From the data in Table 4 above, Comparative Examples 2 and 3 (containing acid-treated nanozirconia fillers) have good radiopacity but have very poor visual opacity (eg, Macbeth values greater than 0.30). It can be concluded that Examples 2 and 3 (representing compositions containing silane-treated nanozirconia fillers) have good radiopacity and good visual opacity (eg, Macbeth values less than 0.30). Comparative Example 4 did not include a zirconia filler and had a poorer radiopacity value.

Claims (28)

(a) polyacids; (b) acid-reactive fillers; (c) water; And (d) (i) zirconia particles having an outer surface and     (ii) a nanozirconia filler comprising a plurality of silane-containing molecules adhered to an outer surface of the zirconia particles Hardening dental composition comprising a. The composition of claim 1 further comprising a polymerizable component. The composition of claim 1, wherein the average zirconia filler has an average particle size of about 100 nm or less. The composition of claim 2 wherein the polymerizable component comprises an ethylenically unsaturated compound. The composition of claim 2 wherein the polymerizable component comprises an ethylenically unsaturated compound having acid functionality. The composition of claim 1, wherein the polyacid comprises a polymer having a plurality of acidic repeating groups but substantially free of polymerizable groups. The composition of claim 6 further comprising a polymerizable component. The composition of claim 1, wherein the polyacid comprises a polymer having a plurality of acidic repeating groups and a plurality of polymerizable groups. The composition of claim 8 further comprising a polymerizable component. The composition of claim 1, wherein the acid-reactive filler is selected from the group consisting of metal oxides, glass, metal salts, and combinations thereof. The composition of claim 10, wherein the acid-reactive filler comprises fluoroaluminosilicate (FAS) glass. The composition of claim 11 comprising less than 50% by weight of FAS glass. The composition of claim 11 comprising less than 30% by weight of FAS glass. The composition of claim 11 comprising less than 20% by weight of FAS glass. The composition of claim 10, wherein the acid-reactive filler comprises an oxyfluoride material. The composition of claim 15, wherein at least 90% by weight of the oxyfluoride material is nanostructured. 6. The composition of claim 5 wherein the acid functionality comprises an oxygen-containing acid of carbon, sulfur, phosphorus or boron. The composition of claim 5 wherein the polyacid and the ethylenically unsaturated compound having acid functionality are the same. The composition of claim 1 wherein the polymerizable component and the polyacid are the same compound. The composition of claim 1, wherein the nanozirconia filler is substantially free of fumed silica and pyrogenic filler. The composition of claim 2 further comprising a redox curing system. The composition of claim 2 further comprising a photoinitiator system. The method of claim 1, wherein the other fillers, pyrogenic fillers, sources of fluoride, whitening agents, caries preventive agents, mineral supplements, enzymes, mouthwashes, anesthetics, coagulants, acid neutralizers, chemotherapy agents, immune response modifiers, medicines, instructions Agents, dyes, pigments, tartaric acid, wetting agents, chelating agents, surfactants, buffers, viscosity modifiers, thixotropic agents, polyols, antibacterial agents, anti-inflammatory agents, antifungal agents, stabilizers, dry mouth cure agents, desensitizers and combinations thereof The composition further comprises at least one additive selected from the group consisting of. The composition of claim 1 selected from the group consisting of dental restorations, dental adhesives, dental cements, tooth decay liners, orthodontic adhesives, dental sealants and dental coatings. The composition of claim 1 comprising a first part and a second part, wherein each part comprises a multi-part composition that can be independently selected from the group consisting of liquids, pastes, gels or powders. (a) providing a dental composition of claim 1; And (b) hardening the dental composition to form a dental article Method for producing a dental article comprising a. 27. The method of claim 26, wherein the dental article is selected from the group consisting of dental mill blanks, dental crowns, dental fillers, dental prostheses and orthodontic devices. (a) a first part comprising a polyacid; (b) a second part comprising an acid-reactive filler; (a) water present in one or both of the parts; (b) any polymerizable component present in one or both of the above parts; And (c) (i) zirconia particles having an outer surface and     (ii) a nanozirconia filler comprising a plurality of silane-containing molecules adhered on the outer surface of the zirconia particles and present in one or both of the parts Comprising, multi-part hardenable dental composition.