JP2025540069A - Surface-treated fillers, dental compositions containing such fillers, methods for making and uses thereof - Patents.com - Google Patents

Abstract

The present invention relates to a dental composition comprising a hardenable component and a surface-treated filler comprising filler particles whose surfaces have been treated with a surface treatment agent, wherein the surface treatment agent is characterized by the following properties: at least one (meth)acrylate moiety, at least one hydrolyzable silane moiety, only one urethane moiety, a linear alkylene moiety AM1 linking at least one (meth)acrylate moiety to the urethane moiety, a linear alkylene moiety AM2 linking at least one hydrolyzable silane moiety to the urethane moiety, and the linear alkylene moiety AM1 containing more carbon atoms than the linear alkylene moiety AM2. The present invention also relates to a method for producing such a dental composition, the use of the dental composition in a dental tooth restoration method, and a kit of parts containing the dental composition.

Description

The present invention relates to surface-treated fillers and dental compositions containing such fillers. Also described are methods for making such fillers and the use of dental compositions to restore teeth. The surface-treated fillers are particularly useful for making flowable or pourable dental compositions that have low viscosity at low shear rates.

Polymerizable dental compositions for restoring missing teeth are widely known.

Dental compositions typically include a resin matrix containing a polymerizable component, an initiator system suitable for curing the polymerizable component, and a filler system.

To achieve sufficient mechanical properties after curing, it is generally desirable to provide a composition with a high filler loading.

However, filler particles often have fairly polar surfaces, while the polymerizable components are fairly non-polar. Therefore, incorporating large amounts of polar filler into a fairly non-polar resin matrix can be difficult.

To address this issue, filler particles are typically surface treated with a silane component, which makes the filler particles more compatible with the resin matrix.

However, as the filler loading increases, the viscosity or consistency of the polymerizable dental composition typically increases, making the dental composition more difficult to handle, particularly during the process of squeezing the dental composition from the packaging device.

Nevertheless, in certain applications, practitioners prefer to have available dental compositions that are fairly low viscosity and flow easily, yet still exhibit sufficient mechanical properties after hardening.

Various attempts in this regard are described in the patent literature.

U.S. Patent No. 10,441,512 (B2) (Tanaka et al.) describes a dental flowable composite composition containing a polymerizable monomer, inorganic particles (A), and inorganic particles (B), where the inorganic particles (A) are surface-treated with a compound represented by general formula (1), and the inorganic particles (B) have at least one of a group represented by general formula (A) and a group represented by general formula (B) present on their surfaces. In the examples, 3-methacryloyloxypropyltrimethoxysilane and 8-methacryloyloxyoctyltrimethoxysilane are primarily used as surface treatment agents. The composite composition is said to have good polishability, abrasion resistance, moldability, handleability, and flexural strength.

U.S. Patent No. 10,975,229 (B2) (Fuchigami et al.) relates to a silane coupling agent and a medical and/or dental hardenable composition containing the same. The silane coupling agent is said to impart high affinity to radically polymerizable monomers, thereby imparting high mechanical strength, flexibility, and durability when used in medical and/or dental hardenable compositions and inorganic fillers surface-treated with the silane coupling agent. The silane coupling agent contains repeating units such as urethane bonds and polyethylene glycol (ether bonds) at specific positions.

U.S. Patent No. 10,561,584 (B2) (Kakinuma et al.) describes a dental adhesive containing a polymerizable monomer, first and second inorganic microparticles each surface-treated with a chemical, and third inorganic microparticles. In the examples, 3-methacryloyloxypropyltrimethoxysilane and 8-methacryloyloxyoctyltrimethoxysilane are primarily used as surface treatment agents.

U.S. Patent No. 10,918,578 (B2) (Murata et al.) describes a dental curable composition containing a polymerizable monomer, inorganic particles (A1) and/or inorganic particles (A2), and inorganic particles (B). The inorganic particles (A1) are surface-treated with a compound represented by general formula (1). The inorganic particles (A2) are surface-treated with a compound represented by general formula (2). The inorganic particles (B) are particles having groups represented by general formula (A) present on their surface, particles having groups represented by general formula (B) present on their surface, and/or particles surface-treated with a compound represented by general formula (3).

U.S. Pat. No. 1,124,6808 (B2) (Craig et al.) describes a dental composition comprising a polymerizable resin containing one or more ethylenically unsaturated monomers or oligomers and nanoparticles. The nanoparticles have a refractive index of at least 1.600 and an average discrete or aggregated particle size of 100 nm or less. The dental composition further comprises an inorganic metal oxide filler having an average discrete or aggregated particle size of at least 200 nm.

U.S. Patent No. 9,050,252 (B2) (Craig et al.) describes a method for surface treating inorganic oxide particles, a hardenable (e.g., dental) composition comprising a polymerizable resin composition and the surface-treated particles, and surface-treated (e.g., nanocluster) inorganic oxide particles, and a silane surface treatment compound. In one embodiment, the method includes forming a surface treatment compound by reacting a first functional group of a (meth)acrylate monomer having a molecular weight of at least 350 g/mol with a second functional group of a silane compound, wherein the first functional group and the second functional group react to form a covalent bond, and combining the surface treatment compound with the inorganic oxide particles.

Various silane treating agents are also described in Japanese Patent Nos. 6,904,646, 6,220,723, 6,173,254, and Publication No. 2021-155395(A).

None of the options outlined in the prior art are entirely satisfactory to practitioners.

There remains a need for hardenable dental compositions that are easy to handle, particularly dental compositions that can be easily applied to the tooth surface being restored.

In particular, there is a need for dental compositions that have little structure, typically with low viscosity at low shear rates.

Furthermore, after hardening, the dental composition should still have sufficient mechanical properties.

One or more of the above objectives are addressed by the present invention as described herein and in the claims.

According to one aspect, the present invention is a surface-treated filler comprising filler particles whose surfaces have been treated with a surface treatment agent, wherein the surface treatment agent has the following properties:
comprising at least one (meth)acrylate moiety;
containing at least one hydrolyzable silane moiety;
containing only one urethane moiety;
comprising a linear alkylene moiety AM1 linking at least one (meth)acrylate moiety to a urethane moiety;
comprising a linear alkylene moiety AM2 linking at least one hydrolyzable silane moiety to a urethane moiety;
The present invention relates to a surface-treated filler characterized in that the linear alkylene moiety AM1 contains more carbon atoms than the linear alkylene moiety AM2.

A further aspect of the present invention is directed to a dental composition comprising a hardenable component and a surface-treated filler, particularly as described herein, in an amount of 40% to 80% by weight, based on the weight of the dental composition.

Another aspect of the present invention is a method for making the surface treated filler described herein, comprising the steps of:
combining the filler particles with a surface treatment, optionally using a dispersion;
reacting a surface treatment agent with the filler particles;
removing the optional dispersing liquid;
optionally drying and sieving the surface-treated filler particles.

A still further aspect of the present invention is a dental composition for use in a method of restoring a tooth in the mouth of a mammal as described herein, the method comprising:
contacting the dental composition with the tooth surface to be restored;
and curing the dental composition by applying radiation.

The present invention further relates to the use of a surface-treated filler to reduce the viscosity of a dental composition at low shear rates, wherein the dental composition comprises a hardenable component and a filler in an amount of 40% to 80% by weight, based on the weight of the dental composition.

Further embodiments are directed to kits of parts that include the dental compositions described herein and the following parts, alone or in combination: dental adhesives, dental curing lights, and application instruments.

Unless otherwise defined, the following terms used herein shall have the given meanings:

A "one-part composition" means that all components of the composition are present together during storage and use. That is, the composition to be applied or used is not prepared by mixing different parts of the composition prior to use. In contrast to one-part compositions, these compositions are often referred to as two-part compositions (e.g., formulated as powder/liquid, liquid/liquid, or paste/paste compositions).

"Two-component composition" means that the components are provided as a kit of parts or system of parts that are separated from one another before use. For use, the respective components or parts must be mixed.

The term "compound" or "component" refers to a chemical substance having a particular molecular identity or consisting of a mixture of such substances, e.g., a polymeric substance.

A "hardenable or curable or polymerizable component" is any component that can be cured or hardened by radiation-induced polymerization in the presence of a photoinitiator. The hardenable component may contain only one, two, three, or more polymerizable groups. Typical examples of polymerizable groups include unsaturated carbon groups, such as vinyl groups present in (methyl)acrylate groups.

As used herein, "(meth)acryl" is a shorthand term that refers to "acryl" and/or "methacryl." For example, a "(meth)acryloxy" group is a shorthand term that refers to either an acryloxy group (i.e., CH ₂ ═CH—C(O)—O—) and/or a methacryloxy group (i.e., CH ₂ ═C(CH ₃ )—C(O)—O—).

As used herein, "solidifying" or "curing" a composition are used interchangeably and refer to polymerization and/or crosslinking reactions, including, for example, photopolymerization reactions and chemical polymerization techniques (e.g., ionic or chemical reactions that form radicals effective to polymerize ethylenically unsaturated compounds), involving one or more materials included in the composition.

"Radiation-curable" shall mean that the component (or composition, as the case may be) can be cured by the application of radiation, preferably electromagnetic radiation of wavelengths in the visible light spectrum under ambient conditions and within a suitable time frame (e.g., within about 60 seconds, 30 seconds, or 10 seconds).

"Paste" means a soft, viscous mass of solids (i.e., particles) dispersed in a liquid.

"Particle" means a solid substance having a geometrically determinable shape. The shape may be regular or irregular. Particles may typically be analyzed, for example, with respect to particle size and particle size distribution.

The particle size (d50) of a powder may be obtained from the cumulative particle size distribution curve. Each measurement may be performed using a commercially available particle size analyzer (e.g., Malvern Mastersizer 2000). "D" represents the diameter of the powder particle, and "50" refers to the volume percentage of the particle. 50% is sometimes expressed as "0.5". For example, "(d50) = 1 μm" means that 50% of the particles have a size of 1 μm or less.

The term "primary particle size" refers to the size of a single, non-associated particle. X-ray diffraction (XRD) is typically used to measure primary particle size using the techniques described herein.

"Nano-sized fillers" are fillers whose individual particles have sizes in the nanometer range, e.g., an average particle diameter of less than 100 nm. Useful examples are described in U.S. Pat. Nos. 6,899,948 (Zhang et al.) and 6,572,693 (Wu et al.).

The measurement of the size of the nanoparticles is preferably based on TEM (transmission electron microscopy) techniques, by which the population is analyzed and the average particle diameter is obtained. A preferred method for measuring particle diameter can be described as follows:
Approximately 80 nm thick samples are placed on 200 mesh copper grids (SPI Supplies, a division of Structure Probe, Inc., West Chester, PA) with carbon-stabilized Formvar substrates. Transmission electron micrographs (TEM) are taken at 200 KV using a JEOL 200CX (JEOL Ltd., Akishima, Japan; sold by JEOL USA, Inc.). Population sizes of approximately 50-100 particles can be measured, and the average diameter is determined.

"Agglomerated" describes a weak association of particles, usually held together by charge or polarity, that can be broken down into smaller entities. The specific surface area of the agglomerated particles does not deviate substantially from the specific surface area of the primary particles that make up the agglomerates (see DIN 53206; 1972).

Agglomerated fillers are commercially available, for example, from Degussa, Cabot Corp. or Wacker under the product names Aerosil™, CAB-O-SIL™ and HDK™.

"Aggregated," as used herein, describes a strong association of particles, often bonded together, for example, by residual chemical treatment or partial sintering. The specific surface area of aggregated particles is typically smaller than the specific surface area of the primary particles that make up the aggregate (see DIN 53206; 1972).

Further breakdown of the aggregates into smaller entities may occur during the polishing process applied to the surface of the composition containing the aggregated filler, but not during dispersion of the aggregated particles in the resin.

Agglomerated fillers and methods for their manufacture and surface treatment are described, for example, in U.S. Patent Nos. 6,730,156 (B1) (Windisch et al.) and 6,730,156 (Windisch et al.).

The term "associated" refers to a grouping of two or more primary particles that are aggregated and/or agglomerated.

Similarly, the term "non-associated" refers to two or more primary particles that are free or substantially free of aggregation and/or agglomeration.

"Non-agglomerated filler" means that the filler particles are present in the resin in a discrete, non-associated (i.e., non-agglomerated and non-aggregated) state. If desired, this can be verified by TEM electron microscopy.

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

"Non-acid-reactive filler" shall mean a filler that, when mixed with a (poly)acid, exhibits no or only a reduced (i.e., time-delayed) chemical reaction within 6 minutes.

To distinguish acid-reactive fillers from non-acid-reactive fillers, the following tests can or should be performed:
A composition was prepared by mixing Part P and Part L in a 3:1 weight ratio, wherein:
Part P contains 100% by weight of the filler to be analyzed;
Part L contains 43.6 wt% poly(acrylic acid co-maleic acid) (Mw: about 18,000 +/- 3,000), 47.2 wt% water, 9.1 wt% tartaric acid, and 0.1 wt% benzoic acid.

The filler is characterized as non-acid reactive if the shear stress is less than 50,000 Pa within 6 minutes after preparing the composition, as determined by oscillatory measurements using a rheometer by applying the following conditions: 8 mm plate, 0.75 mm gap, 28°C, frequency: 1.25 Hz, deformation: 1.75%.

"Cation-reduced aluminosilicate glass" shall mean glass having a lower cation content in the surface region of the glass particle compared to the interior region of the glass particle.

These glasses react much more slowly when in contact with a solution of polyacrylic acid in water compared to typical acid-reactive fillers. An example of a non-acid-reactive filler is quartz glass. Further examples are provided in the text below.

Cation reduction can be achieved by surface treatment of the glass particles. Suitable surface treatments include, but are not limited to, acid washing (e.g., treatment with phosphoric acid or hydrochloric acid), treatment with phosphate salts, or treatment with chelating agents such as tartaric acid.

"Dispersed within the resin" means that the filler particles are present in the resin as agglomerated or aggregated, or as discrete (i.e., non-associated, non-agglomerated, and non-aggregated) particles.

A "urethane group" is a group having the structure "-NH-CO-O-".

A "urea group" is a group having the structure "-NH-CO-NH-".

An "amide group" is a group having the structure "-NH-CO-".

The term "visible light" is used to refer to light having wavelengths between about 400 nanometers (nm) and about 800 nanometers (nm).

"Dental article" refers specifically to an article used in the dental field, specifically as or for producing dental restorations. Dental articles typically have two distinct surface portions: an outer surface and an inner surface. The outer surface is typically the surface that is not in permanent contact with the tooth surface. In contrast, the inner surface is the surface used to attach or secure the dental article to the tooth. If the dental article has the shape of a dental crown, the inner surface typically has a concave shape, while the outer surface typically has a convex shape. Dental articles should not contain ingredients that are harmful to the patient's health and, therefore, do not contain harmful or toxic ingredients that may leach from the dental or orthodontic article.

"Dental restoration" refers to a dental article used to restore a treated tooth. Examples of dental restorations include crowns, bridges, inlays, onlays, veneers, facings, copings, crown-bridge frameworks, and components thereof. "Adhesive" or "dental adhesive" refers to a composition used as a pretreatment on a dental structure (e.g., a tooth) to bond a "dental material" (e.g., a "restorative," an orthodontic appliance (e.g., a bracket), or an "orthodontic adhesive") to the tooth surface. "Orthodontic adhesive" refers to a composition used to bond an orthodontic appliance to a dental (e.g., tooth) surface. Typically, the tooth surface is pretreated, for example, by etching, priming, and/or applying an adhesive, to enhance adhesion of the "orthodontic adhesive" to the tooth surface.

"Dental surface" or "tooth surface" refers to tooth structures (e.g., enamel, dentin, and cementum) and bone surfaces. If a composition does not contain a particular component as an essential characteristic, the composition is "essentially or substantially free of" that component. Thus, the component is not intentionally added to the composition, either by itself or in combination with other components or elements of other components.

A composition that is essentially free of a particular component typically contains that component in an amount of less than about 1% by weight, or less than about 0.5% by weight, or less than about 0.1% by weight, or less than about 0.01% by weight, based on the total composition or material. The composition may not contain this component at all. However, the presence of a small amount of this component may be unavoidable, for example, due to impurities contained in the raw materials used.

"Ambient conditions" refers to the conditions to which the compositions described herein are typically exposed during storage and handling. Ambient conditions may be, for example, a pressure of 900 mbar to 1,100 mbar, a temperature of 10°C to 40°C, and a relative humidity of 10% to 100%. In the laboratory, ambient conditions are typically adjusted to 20°C to 25°C and 1,000 mbar to 1,025 mbar (at sea level pressure).

As used herein, "a," "an," "the," "at least one," and "one or more" are used interchangeably. Also herein, the recitation of numerical ranges by endpoints includes all numbers subsumed within that range (e.g., 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, 5, etc.).

Adding "(s)" to a term means that the term should include the singular and the plural. For example, the term "additive(s)" means one additive and more (e.g., two, three, four, etc.) additives.

Unless otherwise indicated, all numbers expressing quantities of elements, measurements of physical properties, etc., set forth below and used in the specification and claims are to be understood as being modified in all instances by the term "about."

The terms "comprise" or "contain" and variations thereof do not have a limiting meaning when these terms appear in the specification and claims. "Consisting essentially of" means that certain additional components may be present, i.e., components that do not materially affect the essential characteristics of the article or composition. "Consisting of" means that no additional components should be present. The term "comprise" is intended to include the terms "consist essentially of" and "consists of."

If a composition does not contain a particular component as an essential feature, the composition is "essentially or substantially free of" that component. Thus, the component is not intentionally added to the composition, either as is or in combination with other components or elements of other components. A composition that is essentially free of a particular component typically does not contain that component at all. However, the presence of a small amount of that component may be unavoidable, for example, due to impurities contained in the raw materials used.

The surface-treated fillers described herein have been found to have several advantageous properties.

Surface treatment of filler particles not only makes the filler particles more compatible with the resin matrix of the dental composition, but also affects the rheological properties, particularly the viscosity profile, of dental compositions containing these surface-treated filler particles.

The dental composition becomes more flowable and can be more easily dispensed from the syringe-like packaging.

In particular, the dental composition has a low viscosity at low shear rates, indicative of a lack of internal structure, similar to a Newtonian liquid.

Furthermore, it was found that the dental composition after hardening also had sufficient mechanical properties, such as flexural strength and flexural modulus.

While not wishing to be bound by any particular theory, it is believed that the lengths of the two alkylene moieties play a role, and that it is important that the length of the alkylene moiety AM1 is longer than the length of the alkylene moiety AM2. Therefore, the urethane moiety should be located closer to the hydrolyzable silane moiety than the (meth)acrylic moiety.

By selecting the lengths proposed herein, it is believed that the likelihood of undesired hydrogen bridge formation is reduced and the surface treatment agent is more effective at shielding the surface of the treated filler.

In one aspect, the present invention is directed to a surface-treated filler.

The nature and structure of the filler are not particularly limited, as long as the intended purpose cannot be achieved. Different types of fillers can be used.

The dental compositions described herein may include one or more of filler (F1), filler (F2), filler (F3), filler (F4), filler (F5), or filler (F6).

The dental composition may contain only one type of filler (F1), or it may contain multiple types of fillers (F1), for example, two, three, or four different types.

The dental composition may contain only one type of filler (F2), or it may contain multiple types of fillers (F2), for example, two, three, or four different types.

The dental composition may contain only one type of filler (F3), or it may contain multiple types of fillers (F3), for example, two, three, or four different types.

The dental composition may contain only one type of filler (F4), or it may contain multiple types of fillers (F4), for example, two, three, or four different types.

The dental composition may contain only one type of filler (F5), or it may contain multiple types of fillers (F5), for example, two, three, or four different types.

The dental composition may contain only one type of filler (F6), or it may contain multiple types of fillers (F6), for example, two, three, or four different types.

Overall, dental compositions typically contain fillers in an amount of at least 40%, 45%, or 50% by weight, up to 80%, 75%, or 70% by weight, in an amount ranging from 40% to 80%, 45% to 75%, or 50% to 70% by weight, where the weight percentages are based on the weight of the dental composition.

Filler (F1) comprises non-aggregated, non-agglomerated nano-sized particles of SiO ₂ , ZrO ₂ and mixtures thereof.

The nano-sized particles are preferably substantially spherical and substantially non-porous.

The filler (F1) typically has the following properties:
a) specific surface area (BET): 50 m ² /g to 400 m ² /g, or 60 m ² /g to 300 m ² /g, or 80 m ² /g to 250 m ² /g;
b) Primary particle size: 5 nm to 30 nm, or 7 nm to 20 nm,
c) containing particles of SiO ₂ , ZrO ₂ , and mixtures thereof.

Fillers (F1) characterized by properties a) and c) are sometimes preferred.

If desired, the specific surface area can be determined according to the Brunauer, Emmett and Teller (BET) method by using a device available from Quantachrome (Monosorb).

Silica is an example of a preferred nano-sized filler (F1). The silica is preferably essentially pure, but may contain small amounts of stabilizing ions such as ammonium and alkali metal ions.

Zirconia is another preferred nano-sized filler (F1). Useful methods for making zirconium oxide are described, for example, in U.S. Pat. No. 6,376,590 (B1) (Kolb et al.).

This application discloses a zirconia sol comprising an aqueous phase in which a plurality of single-crystal zirconia particles having an average primary particle size of less than 20 nm, preferably in the range of 7 nm to 20 nm, are dispersed. The zirconia sol is substantially non-associated (i.e., non-aggregated and non-agglomerated).

Non-agglomerated nano-sized silica is commercially available, for example, from Nalco Chemical Co. (Naperville, Ill.) under the product name NALCO COLLOIDAL SILICAS, e.g., NALCO product numbers 1040, 1042, 1050, 1060, 2327, and 2329. Non-agglomerated fillers are used and described, for example, in U.S. Pat. No. 7,393,882 (3M).

The filler (F2) comprises aggregated nano-sized particles.

The filler (F2) typically has the following properties:
a) specific surface area (BET): 30 m ² /g to 400 m ² /g, or 50 m ² /g to 400 m ² /g, or 60 m ² /g to 300 m ² /g, or 80 m ² /g to 250 m ² /g;
b) primary particle size: 5 nm to 100 nm, or 10 nm to 80 nm, or 10 nm to 50 nm;
c) Average particle size (agglomerates): 0.5 μm to 2 μm,
d) containing particles of SiO ₂ , ZrO ₂ , and mixtures thereof, alone or in combination.

Fillers (F2) characterized by properties a) and c), or a) and d), or a), c) and d) are sometimes preferred.

According to one embodiment, the filler (F2) is characterized by a primary particle size ranging from 50 nm to 100 nm and a specific surface area (BET) ranging from 30 m ² /g to 50 m ² /g.

Optionally, the average particle size can be determined by light scattering, for example, using a Malvern Mastersizer 2000 device available from Malvern Instruments.

Filler (F2) can be prepared, for example, according to the method described in U.S. Pat. No. 6,730,156 (B1) (Windisch et al.).

Specifically, filler (F2) can be prepared from a suitable sol and one or more oxygen-containing heavy metal compound solution precursors, which may be salts, sols, solutions, or nano-sized particles. Of these, sols are preferred. For purposes of this invention, a sol is defined as a stable dispersion of colloidal solid particles in a liquid. The solid particles are typically denser than the surrounding liquid and small enough so that dispersing forces are greater than gravity. Furthermore, the particles are of a small enough size so as not to generally refract visible light. Judicious selection of the precursor sol results in the desired degree of visual opacity, strength, etc. Factors guiding the selection of a sol depend on a combination of the following properties: a) the average size of the individual particles is preferably less than about 100 nm in diameter; b) acidity: the pH of the sol should preferably be less than 6, more preferably less than 4; and c) the sol should be free of impurities (during the filler preparation process) that would cause excessive aggregation of the individual discrete particles into larger-sized particles that cannot be easily dispersed or converted during subsequent steps such as spray drying or calcination, thereby reducing translucency and abrasiveness.

If the starting sol is basic, it should be acidified, for example, by adding nitric acid or another suitable acid to lower the pH. However, selecting a basic starting sol is less desirable because it requires additional steps and may result in the introduction of undesirable impurities. Typical impurities that are preferably avoided are metal salts, particularly salts of alkali metals, such as sodium.

The non-heavy metal sol and heavy metal oxide precursor are preferably mixed together in a molar ratio that matches the refractive index of the solidifiable resin. This imparts low and desirable visual opacity. Preferably, the molar ratio range of non-heavy metal oxide ("non-HMO") to heavy metal oxide ("HMO"), expressed as non-HMO:HMO, is in the range of 0.5:1 to 10:1, more preferably 3:1 to 9:1, and most preferably 4:1 to 7:1.

In a preferred embodiment in which the aggregated nano-sized particles contain silica and a zirconium-containing compound, the preparation method begins with a mixture of silica sol and zirconyl acetate in a molar ratio of approximately 5.5:1.

Before mixing the non-heavy metal oxide sol with the heavy metal oxide precursor, it is preferable to lower the pH of the non-heavy metal oxide sol to obtain an acidic solution with a pH of 1.5 to 4.0.

The non-heavy metal oxide sol is then slowly mixed with a solution containing the heavy metal oxide precursor and vigorously stirred. Vigorous stirring is preferably performed throughout the blending process. The solution is then dried to remove water and other volatile components. Drying can be accomplished by a variety of methods, including, for example, tray drying, fluidized bed drying, and spray drying. A preferred method using zirconyl acetate is drying by spray drying.

The resulting dried material preferably consists of small, substantially spherical particles as well as broken hollow spheres. These fragments are then batch fired to further remove residual organic matter. Removal of residual organic matter allows the filler to become more brittle, which results in more efficient particle size reduction. The soaking temperature during firing is preferably between 200°C and 800°C, more preferably between 300°C and 600°C. Soaking is performed for 0.5 hours to 8 hours, depending on the amount of material being fired. The soaking time for the firing step is preferably such that a flat surface area is obtained. The time and temperature are preferably selected so that the resulting filler is white, as determined by visual inspection, and does not contain black, gray, or amber particles.

The calcined material is then preferably ground to a median particle size of less than 5 μm, preferably less than 2 μm (by volume), as can be determined by using a Sedigraph 5100 (Micrometrics, Norcross, GA). Particle size determination can be performed by first obtaining the specific gravity of the filler using an Accuracy 1330 Pycometer (Micrometrics, Norcross, GA). Grinding can be accomplished by a variety of methods, including, for example, agitator milling, vibratory milling, fluid energy milling, jet milling, and ball milling. Ball milling is the preferred method.

The resulting filler comprises, contains, consists essentially of, or consists of aggregated nano-sized particles. Optionally, this can be verified by transmission electron microscopy (TEM).

Once dispersed in the resin, the filler (F2) remains in the aggregated stage, i.e., the particles are not broken down into discrete (i.e., individual) and non-associated (i.e., non-agglomerated, non-aggregated) particles during the dispersion process.

While not wishing to be bound by any particular theory, it is believed that filler (F2) contributes to the polishing properties of the dental compositions described herein. It has been found that aggregates of filler (F2) particles can be broken down during the polishing process, contributing to smooth surfaces and lower light scattering compared to rough surfaces. From a clinical perspective, this typically results in higher gloss retention and color stability.

When present, filler (F2) is typically present in an amount of at least 30 wt%, or 35 wt%, or 40 wt%, and up to 70 wt%, or 60 wt%, or 50 wt%, and in an amount ranging from 30 wt% to 70 wt%, or 35 wt% to 60 wt%, or 40 wt% to 50 wt%, where wt% is based on the weight of the dental composition.

The filler (F3) may include agglomerated nano-sized particles.

According to one embodiment, the filler (F3) has the following characteristics:
a) specific surface area (BET): 30 m ² /g to 400 m ² /g, or 50 m ² /g to 300 m ² /g, or 70 m ² /g to 250 m ² /g;
b) containing particles of SiO ₂ , ZrO ₂ , Al ₂ O ₃ and mixtures thereof, alone or in combination.

If desired, the specific surface area can be determined as described above.

Suitable agglomerated nanoparticles include fumed silica, such as Aerosil™, e.g., Aerosil OX-130, -150, and -200; Aerosil R8200 available from Degussa AG (Hanau, Germany); CAB-O-SIL™ M5 available from Cabot Corp (Tuscola, Illinois); and HDK™, e.g., HDK-H 2000, HDK H15, HDK H18, HDK H20, and HDK H30 available from Wacker.

Without wishing to be bound by any particular theory, it is believed that filler (F2) contributes to the rheological behavior of the dental compositions described herein.

The use of this type of filler makes it possible to provide a highly filled dental composition that is still mixable using a static mixing tip. From a clinical standpoint, this typically results in improved handling properties, such as easier mixing of the paste and lower extrusion forces from cartridge systems.

When present, filler (F3) is typically present in an amount of at least 1 wt%, or 3 wt%, or 5 wt%, and up to 20 wt%, or 15 wt%, or 10 wt%, and in an amount ranging from 1 wt% to 20 wt%, or 3 wt% to 15 wt%, or 5 wt% to 10 wt%, where wt% is based on the weight of the dental composition.

Fillers (F4) include non-acid-reactive glasses such as lanthanum glass, borosilicate glass, soda glass, barium glass, strontium glass, glass ceramics, aluminum silicate glass, barium boroaluminosilicate glass, strontium boroaluminosilicate glass, silicates such as calcium silicate and zirconium silicate, as well as metal oxides such as quartz, cristobalite, alumina, titania, silica-titania, silica-titania-barium oxide, silica-zirconia, and silica-alumina.

In particular, the following glasses have been found to be useful: barium glass, strontium glass, aluminosilicate glass, barium boroaluminosilicate glass, and strontium boroaluminosilicate glass.

Useful glasses are commercially available, for example, from Schott, such as GM32087, GM27884, G018-053, G018-308, G018-431, and G018-432.

Optionally, the filler (F4) has the following properties:
a) specific surface area (BET): 10 m ² /g to 50 m ² /g, or 15 m ² /g to 40 m ² /g;
b) Average particle size: 0.1 μm to 1 μm, or 0.2 μm to 0.6 μm
may be characterized by either alone or in combination.

When present, filler (F4) is typically present in an amount of at least 1 wt%, or 5 wt%, or 10 wt%, and up to 80 wt%, or 70 wt%, or 60 wt%, and in an amount ranging from 1 wt% to 80 wt%, or 5 wt% to 70 wt%, or 10 wt% to 60 wt%, where wt% is based on the weight of the dental composition.

Filler (F5) includes an acid-reactive filler, particularly an acid-reactive glass.

Acid-reactive fillers can help tailor the hardening behavior and adhesion of dental compositions by adjusting the pH during the hardening process.

Acid-reactive fillers typically have the following properties:
a) Average particle size: about 3 μm to about 10 μm,
b) (d10/μm): 0.5 μm to 3 μm, (d50/μm): 2 μm to 7 μm, (d90/μm): 6 μm to 15 μm
may be characterized by either alone or in combination.

Examples of fillers (F5) include metal oxides and hydroxides, such as calcium, magnesium, or zinc, with calcium hydroxide sometimes being preferred, and acid-reactive glasses, particularly fluoroaluminosilicate glasses (FAS glasses).

Acid-reactive glasses can be produced by melting glass frits containing the respective glass components and crushing and grinding the glass frits until the desired particle size distribution is obtained. Glass components that can be used include _Al2O3 , _SiO2 , _SrF2 , and _AlF3 hydrate, or _AlF3 . Milling or grinding of the glass frits can be carried out, for example _, using a ball mill.

The Al/Si ratio of acid-reactive glasses is typically greater than 1/1 by weight. This means that the acid-reactive glass contains more Al than Si. Al/Si ratios in the range of greater than 1.0/1.0 to 1.6/1.0, or greater than 1.0/1.0 to 1.4/1.0 by weight, are often preferred.

When present, filler (F5) is typically present in an amount of at least 1 wt%, or 5 wt%, or 10 wt%, up to 80 wt%, or 70 wt%, or 60 wt%, in an amount ranging from 1 to 80 wt%, or 5 to 70 wt%, or 10 to 60 wt%, where wt% is based on the weight of the dental composition.

Filler (F6) includes heavy metal oxides and fluorides. Filler (F6) may contribute to increasing the radiopacity of the composition.

"Radiopacity" describes the ability of a hardened dental material to be distinguished from tooth structure in a conventional manner using standard dental x-ray equipment. Radiopacity in dental materials is advantageous in certain instances where x-rays are used to diagnose dental conditions. For example, radiopaque materials allow for the detection of secondary caries that may have formed in the tooth tissue surrounding a filling.

Oxides or fluorides of heavy metals with atomic numbers greater than 28 may be preferred. The heavy metal oxide or fluoride should be selected so as not to impart an undesirable color or shade to the hardened resin in which it is dispersed. For example, iron and cobalt are undesirable because they impart a dark, contrasting color to the neutral tooth color of the dental material. More preferably, the heavy metal oxide or fluoride is an oxide or fluoride of a metal with an atomic number greater than 30. Suitable metal oxides are oxides of yttrium, strontium, barium, zirconium, hafnium, niobium, tantalum, tungsten, bismuth, molybdenum, tin, zinc, the lanthanides (i.e., elements with atomic numbers ranging from 57 to 71, inclusive), cerium, and combinations thereof. Suitable metal fluorides include, for example, yttrium trifluoride and ytterbium trifluoride. Most preferably, oxides and fluorides of heavy metals having atomic numbers greater than 30 but less than 72 are optionally included in the materials of the present invention. Particularly preferred radiopaque metal oxides include lanthanum oxide, zirconium oxide, yttrium oxide, ytterbium oxide, barium oxide, strontium oxide, cerium oxide, and combinations thereof. The heavy metal oxide particles may be aggregated. In that case, the aggregated particles preferably have an average diameter of 200 nm or less. Other suitable fillers that enhance radiopacity are barium and strontium salts, particularly strontium sulfate and barium sulfate.

When present, filler (F6) is typically present in an amount of at least 1 wt%, or 3 wt%, or 5 wt%, and up to 50 wt%, or 40 wt%, or 30 wt%, and in an amount ranging from 1 wt% to 50 wt%, or 3 wt% to 40 wt%, or 5 wt% to 30 wt%, where wt% is based on the weight of the dental composition.

In certain embodiments, the dental composition may include a combination of fillers (F1) and (F2), or (F1) and (F3), or (F2) and (F6), or (F1), (F2) and (F6), or (F2), (F3) and (F6), with the combination of fillers (F2) and (F6) sometimes being preferred.

The surface treatment agent is as follows:
a. comprising at least one (meth)acrylate moiety;
b. comprising at least one hydrolyzable silane moiety;
c. containing only one urethane moiety;
d. comprising a linear alkylene moiety AM1 linking at least one (meth)acrylate moiety to a urethane moiety;
e. comprising a linear alkylene moiety AM2 connecting at least one hydrolyzable silane moiety to a urethane moiety;
f) the linear alkylene moiety AM1 contains more carbon atoms than the linear alkylene moiety AM2.

The surface treatment agent does not contain a polyol moiety (e.g., a polyethylene or polypropylene moiety).

While not wishing to be bound by any particular theory, the presence of polyol moieties in combination with urethane moieties may result in hydrogen bonding interactions, which may create undesirable internal structure within the composition.

More precisely, the surface treatment agent is:
a. containing only one (meth)acrylate moiety;
b. comprising at least one hydrolyzable silane moiety;
c. containing only one urethane moiety;
d. Containing one linear alkylene moiety AM1 connecting the (meth)acrylate moiety to the urethane moiety, wherein the alkylene moiety AM1 contains 6 to 12 C atoms;
e. comprises one linear alkylene moiety AM2 linking at least one hydrolyzable silane moiety with a urethane moiety, the linear alkylene moiety AM2 comprising 1 to 4 C atoms.

The hydrolyzable portion of the silane moiety is typically
-Si(R ² ) _o (R ³ ) _3-o
wherein R ¹ =H or CH ₃ , R ² =Cl, Br, O—C _1-4 alkyl, O—C _1-4 acyl, R ³ =C _1-4 alkyl, X=O, Y=NH, n=6-12, m=1-4, o=1-3.
is selected from.

Tri-alkyloxysilanes, particularly tri-methoxysilane, tri-ethoxysilane, tri-propyloxysilane, or tri-butyloxysilane moieties, are often preferred.

Even more precisely, the surface treatment agent has the following formula:
H ₂ C=CHR ¹ -CO-O-(CH ₂ ) _n -X-CO-Y-(CH ₂ ) _m -Si(R ² ) _o (R ³ ) _3-o
wherein R ¹ =H or CH ₃ , R ² =Cl, Br, O—C _1-4 alkyl, O—C _1-4 acyl; R ³ =C _1-4 alkyl; X=O, Y=NH; n=6-12; m=1-4; o=1-3.
It can be characterized by:

A preferred embodiment of the hydrolyzable silane moiety is represented by the following formula:
H ₂ C=CHR ¹ -CO-O-(CH ₂ ) _n -X-CO-Y-(CH ₂ ) _m -SiR ² ₃
wherein R ¹ =H or CH ₃ , R ² =Cl, Br, OCH ₃ , OCH ₂ CH ₃ , OCH ₂ CH ₂ CH ₃ , OCH ₂ CH ₂ CH ₂ CH ₃ , X=O, Y=NH, n=6-12, m=1-4.
is expressed by

The surface treatment agent typically has a molecular weight (Mw) in the range of 300 g/mol to 800 g/mol, or 350 g/mol to 600 g/mol.

Specific examples of surface treatment agents include the following molecules:

The surface treatment agent is
a (meth)acrylate component containing a hydroxy moiety,
The polyisocyanate silane compound can be prepared by a method comprising the step of reacting a polyisocyanate silane compound with a hydrolyzable isocyanate silane component.

The reaction is typically carried out at slightly elevated temperatures (e.g., 40°C to 80°C).

The surface-treated filler is
combining the filler particles with a surface treatment, optionally using a dispersion;
reacting a surface treatment agent with the filler particles;
removing the optional dispersing liquid;
optionally drying and sieving the surface-treated filler particles.

Suitable dispersion liquids include water and alcohols such as methanol, ethanol, or propanol. If desired, the pH of the dispersion can be adjusted, for example, by adding aqueous ammonia.

In some embodiments, reacting the surface treatment agent with the filler particles comprises hydrolysis, i.e., reaction of water with at least one of the hydrolyzable silane groups, and condensation of the resulting silanol groups to the filler surface and/or to another surface treatment agent molecule. In some embodiments, the surface-treated filler comprises a partially or fully hydrolyzed surface treatment agent. In some embodiments, the partially or fully hydrolyzed surface treatment agent is fully or partially condensed to form siloxane bonds between adjacent surface treatment agent molecules or to form siloxane bonds between the surface treatment agent and the filler surface. In some embodiments, some portion of the hydrolyzed and/or condensed surface treatment agent can be removed from the surface-treated filler by immersing the surface-treated filler in an alcohol containing a catalyst effective for re-esterification, i.e., reforming the hydrolyzable silane moieties. Effective catalysts include, but are not limited to, hydrofluoric acid, sodium fluoride, tetramethylammonium fluoride, tetrabutylammonium fluoride, hydrochloric acid, p-toluenesulfonic acid, and trifluoromethanesulfonic acid.

In another aspect, the present invention is directed to a dental composition comprising the surface-treated filler described herein.

Dental compositions typically include a filler system, a resin matrix, and an initiator system. The filler system includes a surface-treated filler as described herein. The resin matrix includes a hardenable component.

Dental compositions typically have the following properties before hardening:
It is capable of being solidified within 10 minutes after being irradiated with light having a wavelength in the range of 400 nm to 700 nm.
pH value: 7 or less, either alone or in combination.

Dental compositions that do not contain a rheology modifier typically have a viscosity in the range of 5 to 1,500 ^Pa* s at 25° C. and a shear rate of 0.01 ^{s −1} .

Dental compositions typically have the following properties after hardening:
Flexural strength: determined to be 100 MPa to 200 MPa according to ISO 4049 (2019);
Flexural modulus: determined to be 4 GPa to 8 GPa according to ISO 4049 (2019).

If desired, these properties can be determined as described in the Examples section.

The dental composition includes a hardenable component.

The hardenable component is part of the resin matrix. One or more different hardenable components may be present.

The curable component typically includes one or more polymerizable moieties, particularly (meth)acrylate moieties. Additionally, the curable component may or may not include acidic moieties.

The hardenable component is typically present in an amount of at least 5%, 10%, or 15% by weight, up to 50%, 45%, or 40% by weight, in an amount ranging from 5% to 50%, 10% to 45%, or 15% to 40% by weight, where the weight percentages are based on the dental composition.

Suitable polymerizable components that do not contain acidic moieties that can be used are represented by the following formula:
A _n BA _m
wherein A is an ethylenically unsaturated group such as a (meth)acrylic moiety;
B is selected from (i) linear or branched C _{1 -C 12} alkyl optionally substituted with other functional groups (e.g., halides (including Cl, Br, I), OH, or mixtures thereof), (ii) C ₆ -C ₁₂ aryl optionally substituted with other functional groups (e.g., halides, OH, or mixtures thereof), or (iii) organic groups having 4 to ₂₀ carbon atoms bonded together by one or more ether, thioether, ester, thioester, thiocarbonyl, amide, urethane, carbonyl, and/or sulfonyl bonds;
m, n are independently selected from 0, 1, 2, 3, 4, 5, or 6, provided that n+m is greater than 0, i.e., at least one A group is present.
can be characterized by

Such polymerizable materials include:
Mono-, di- or poly-acrylates and methacrylates, for example methyl acrylate, methyl methacrylate, ethyl (meth)acrylate, isopropyl (meth)acrylate, n-hexyl (meth)acrylate, stearyl (meth)acrylate, allyl (meth)acrylate, glycerol di(meth)acrylate,
urethane dimethacrylate, known as UDMA (urethane dimethacrylate, a mixture of isomers, e.g., Rohm Plex 6661-0), which is the reaction product of 2-hydroxyethyl methacrylate (HEMA) and 2,2,4-trimethyl-hexamethylene diisocyanate (TMDI);
Glycerol tri(meth)acrylate, ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate di(meth)acrylate, TEGDMA), 1,3-propanediol diacrylate, 1,3-propanediol dimethacrylate, 1,6-hexanediol di(meth)acrylate, 1,10-decanediol di(meth)acrylate, 1,12-dodecanediol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, 1,2,4-butanetriol tri(meth)acrylate, 1,4-cyclohexanediol di(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetraacrylate, pentaerythritol tetramethacrylate, sorbitol hexa(meth)acrylate, bis[1-(2-(meth)acryloxy)]-p-ethoxy-phenyldimethylmethane, and trishydroxyethyl-isocyanurate trimethacrylate,
bis-acrylates and bis-methacrylates of polyethylene glycols of molecular weight 200 to 500, copolymerizable mixtures of acrylated monomers (see, e.g., U.S. Pat. No. 4,652,274 (Boettcher et al.)), and acrylated oligomers (see, e.g., U.S. Pat. No. 4,642,126 (Zador et al.));
Vinyl compounds such as styrene, divinyl succinate, divinyl adipate, and divinyl phthalate, and multifunctional (meth)acrylates containing urethane, urea, or amide groups.

Mixtures of two or more of these free-radically polymerizable materials can be used if desired.

When present, polymerizable components not having acidic moieties are typically present in an amount of at least 1 wt%, or at least 2 wt%, or at least 5 wt%, or up to 20 wt%, or up to 15 wt%, or up to 10 wt%, or in an amount ranging from 1 wt% to 20 wt%, or from 2 wt% to 15 wt%, or from 5 wt% to 10 wt%, where wt% is based on the weight of the dental composition.

The dental composition may also include a polymerizable monomer having an acidic moiety.

The polymerizable component having an acid moiety typically has the following formula:
A _n BC _m
wherein A is an ethylenically unsaturated group such as a (meth)acrylic moiety;
B is (i) a linear or branched C _{1 -C 12} alkyl optionally substituted with other functional groups (e.g., halides (including Cl, Br, I), OH, or mixtures thereof); (ii) a C ₆ -C ₁₂ aryl optionally substituted with other functional groups (e.g., halides, OH, or mixtures thereof); (iii) a spacer group such as an organic group having 4 to ₂₀ carbon atoms bonded together by one or more ether, thioether, ester, thioester, thiocarbonyl, amide, urethane, carbonyl, and/or sulfonyl bonds;
C is an acidic group or a precursor of an acidic group such as an acid anhydride;
m and n are independently selected from 0, 1, 2, 3, 4, 5, or 6;
wherein the acidic group comprises one or more carboxylic acid residues, such as —COOH or —CO—O—CO—, phosphoric acid residues, such as —O—P(O)(OH)OH, phosphonic acid residues, such as —P(O)(OH)(OH), sulfonic acid residues, such as —SO ₃ H, or sulfinic acid residues, such as —SO ₂ H.
can be characterized by

Examples of polymerizable compounds having an acidic moiety include glycerol phosphate mono(meth)acrylate, glycerol phosphate di(meth)acrylate, hydroxylethyl (meth)acrylate (e.g., HEMA) phosphate, bis((meth)acryloxyethyl)phosphate, ((meth)acryloxypropyl)phosphate, bis((meth)acryloxypropyl)phosphate, bis((meth)acryloxy)propyloxyphosphate, (meth)acryloxyhexylphosphate, bis((meth)acryloxyhexyl)phosphate, (meth)acryloxyoctylphosphate, bis((meth) Examples of suitable solidifying components include (meth)acryloxyoctyl)phosphate, (meth)acryloxydecyl phosphate, bis((meth)acryloxydecyl)phosphate, caprolactone 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 polysulfonate, and poly(meth)acrylated polyboric acid. Derivatives of these solidifying components, such as acid halides or anhydrides, having acid moieties that can readily react with water to form the specific examples mentioned above, are also contemplated.

Also, monomers, oligomers, and polymers of unsaturated carboxylic acids such as (meth)acrylic acid, aromatic (meth)acrylated acids (e.g., methacrylated trimellitic acid), and their anhydrides can be used.

Some of these compounds can be obtained, for example, as the reaction product between an isocyanatoalkyl (meth)acrylate and a carboxylic acid. Additional compounds of this type having both acid-functional and ethylenically unsaturated components are described in U.S. Pat. No. 4,872,936 (Engelbrecht) and U.S. Pat. No. 5,130,347 (Mitra). A wide variety of such compounds containing both ethylenically unsaturated and acid moieties can be used. Mixtures of such compounds can be used if desired.

The use of (meth)acrylate-functionalized polyalkenoic acids is often preferred, as these components have been found to be useful in improving properties such as adhesion to dental hard tissue, homogeneous layer formation, viscosity, or moisture resistance.

According to one embodiment, the composition contains a (meth)acrylate-functionalized polyalkenoic acid, such as AA:ITA:IEM (acrylic acid:itaconic acid copolymer with pendant methacrylate).

These components can be prepared, for example, by reacting an AA:ITA copolymer with 2-isocyanatoethyl methacrylate to convert some of the acid groups of the AA:ITA copolymer to pendant methacrylate groups. Methods for preparing these components are described, for example, in Example 11 of U.S. Pat. No. 5,130,347 (Mitra) and are cited in U.S. Pat. Nos. 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.), EP 0 712,622 (A1) (Tokuyama Corporation), and EP 1,051,961 (Kuraray Co., Ltd.).

If present, polymerizable components having acidic moieties should be present in an amount such that the pH of the composition, when contacted with water, is less than 6, or less than 4, or less than 2.

When present, polymerizable components having acidic moieties are typically present in an amount of at least 1 wt%, or at least 2 wt%, or at least 5 wt%, or up to 20 wt%, or up to 15 wt%, or up to 10 wt%, or in an amount ranging from 1 wt% to 20 wt%, or from 2 wt% to 15 wt%, or from 5 wt% to 10 wt%, where wt% is based on the weight of the dental composition.

Optionally, an addition fragmentation monomer (AFM) may also be added.

Addition-cleavage monomers have the following formula:

[In the formula,
R ¹ , R ² , and R ³ are each independently Z _m -Q-, a (hetero)alkyl group, or a (hetero)aryl group, with the proviso that at least one of R ¹ , R ² , and R ³ is Z _m -Q-, Q is a linking group having a valence of m+1, Z is an ethylenically unsaturated polymerizable group, m is 1 to 6, each X ¹ is independently —O— or —NR ⁴ — (wherein R ⁴ is H or C ₁ to C ₄ alkyl), and n is 0 or 1.
can be characterized by

These monomers are said to reduce stress. Suitable monomers are also described in U.S. Pat. No. 9,056,043 (Joly et al.).

Monomers containing hydroxyl moieties may also be present.

Suitable compounds include 2-hydroxyethyl (meth)acrylate (HEMA), 2- or 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 5-hydroxypentyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, dialkylene glycol mono(meth)acrylates, such as diethylene glycol mono(meth)acrylate, triethylene glycol mono(meth)acrylate, tetraethylene glycol mono(meth)acrylate, polyethylene glycol mono(meth)acrylate, and dipropylene glycol mono(meth)acrylate. acrylate, polypropylene glycol mono(meth)acrylate, and further examples include 1,2- or 1,3- and 2,3-dihydroxypropyl(meth)acrylate, 2-hydroxypropyl-1,3-di(meth)acrylate, 3-hydroxypropyl-1,2-di(meth)acrylate, N-(meth)acryloyl-1,2-dihydroxypropylamine, N-(meth)acryloyl-1,3-dihydroxypropylamine, adducts of phenol and glycidyl(meth)acrylate, such as 1-phenoxy-2-hydroxypropyl(meth)acrylate, and 1-naphthoxy-2-hydroxypropyl(meth)acrylate.

If desired, a mixture of one or more of these ingredients can be used.

The dental composition also includes an initiator system suitable for hardening the hardenable component.

The initiator system can be a redox initiator system, a photoinitiator system, or a thermosetting system. The initiator system can initiate the curing process of the solidifiable components present in the resin matrix.

The initiator system is typically present in an amount of at least 0.1 wt%, or at least 0.2 wt%, or at least 0.5 wt%, or up to 5 wt%, or up to 4 wt%, or up to 3 wt%, or in an amount ranging from 0.1 wt% to 5 wt%, or from 0.2 wt% to 4 wt%, or from 0.5 wt% to 3 wt%, where wt% is based on the weight of the dental composition.

A photoinitiator system is typically used to cure one-part compositions.

Suitable photoinitiator systems for free radical polymerization are generally known to those skilled in the art of working with dental materials.

Suitable photoinitiator systems often contain a sensitizer containing an alpha-alpha di-keto moiety, an anthraquinone moiety, a thioxanthone moiety, or a benzoin moiety. Sensitizers containing an alpha-alpha di-keto moiety are often preferred.

A typical photoinitiator system includes a combination of a sensitizer and a reducing agent or donor component, often referred to as a photoinitiator system.

Preferably, the sensitizer is one that can polymerize the polymerizable monomer under the action of visible light with a wavelength of 390 nm to 830 nm.

Examples of sensitizers that can be used include camphorquinone, benzil, diacetyl, benzil dimethyl ketal, benzil diethyl ketal, benzil di(2-methoxyethyl) ketal, 4,4,'-dimethylbenzyl dimethyl ketal, anthraquinone, 1-chloroanthraquinone, 2-chloroanthraquinone, 1,2-benzanthraquinone, 1-hydroxyanthraquinone, 1-methylanthraquinone, 2-ethylanthraquinone, 1-bromoanthraquinone, thioxanthone, 2-isopropylthioxanthone, and 2-nitrothioxanthone. Examples include thionone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, 2,4-diisopropylthioxanthone, 2-chloro-7-trifluoromethylthioxanthone, thioxanthone-10,10-dioxide, thioxanthone-10-oxide, benzoin methyl ether, benzoin ethyl ether, isopropyl ether, benzoin isobutyl ether, benzophenone, bis(4-dimethylamino-phenyl)ketone, and 4,4,'-bisdiethylaminobenzophenone.

Tertiary amines are commonly used as reducing agents or donor components. Suitable examples of tertiary amines include N,N-dimethyl-p-toluidine, N,N-dimethylaminoethyl methacrylate, triethanolamine, methyl 4-dimethylaminobenzoate, ethyl 4-dimethylaminobenzoate, methyldiphenylamine, and isoamyl 4-dimethylaminobenzoate.

Further suitable reducing agents include diarylalkylamines characterized by the formula Ar ¹ Ar ² RN, where Ar ¹ and Ar ² are independently selected from phenyl or alkyl (e.g., C ₁ -C ₄ ) substituted phenyl, R is an alkyl (e.g., C ₁ -C ₄ ) group in which one or more H atoms may be replaced by halogen, and N is nitrogen. These reducing agents are described in more detail in U.S. Pat. No. 8,314,162 (Hailand et al.).

In addition, a ternary photopolymerization initiation system consisting of a sensitizer, electron donor, and onium salt can also be used.

Examples are described in U.S. Patent Nos. 6,187,833 (Oxman et al.), 6,025,406 (Oxman et al.), 6,043,295 (Oxman et al.), 5,998,495 (Oxman et al.), 6,084,004 (Weinmann et al.), 5,545,676 (Palazzotto et al.), and 8,314,162 (B2) (Hailand et al.), and 6,765,036 (Dede et al.).

In a ternary photoinitiator system, the first component is an onium, preferably an iodonium salt, i.e., a diaryliodonium salt.

The iodonium salt is preferably soluble in the monomer and shelf-stable (i.e., does not spontaneously promote polymerization) when dissolved in the monomer in the presence of the sensitizer and donor. Thus, the selection of a particular iodonium salt may depend, in part, on the particular monomer, polymer, or oligomer, sensitizer, and donor selected. Suitable iodonium salts are described, for example, in U.S. Pat. Nos. 3,729,313 (Smith et al.), 3,741,769, 3,808,006 (Smith et al.), 4,250,053 (Smith et al.), and 4,394,403 (Smith et al.).

The iodonium salt can be a simple salt (e.g., containing anions such as Cl ^- , Br ^- , I ^- , or C ₄ H ₅ SO ₃ ^- ) or a complex metal salt (e.g., containing SbF ₅ OH ^- or AsF ₆ ^- ). Mixtures of iodonium salts can be used if desired. Preferred iodonium salts include diphenyliodonium salts, such as diphenyliodonium chloride, diphenyliodonium hexafluorophosphate, and diphenyliodonium tetrafluoroborate.

The second component of a ternary photoinitiator system is a sensitizer.

The sensitizer is desirably soluble in the monomer and capable of absorbing light within a wavelength range of greater than 400 nm to 1200 nm, more preferably greater than 400 nm to 700 nm, and most preferably greater than 400 nm to 600 nm.

Suitable sensitizers include compounds from the following categories: ketones, coumarin dyes (e.g., ketocoumarins), xanthene dyes, acridine dyes, thiazole dyes, thiazine dyes, oxazine dyes, azine dyes, aminoketone dyes, porphyrins, aromatic polycyclic hydrocarbons, p-substituted aminostyryl ketone compounds, aminotriarylmethanes, merocyanines, squarylium dyes, and pyridinium dyes. Ketones (e.g., monoketones or alpha-diketones), ketocoumarins, aminoaryl ketones, and p-substituted aminostyryl ketone compounds are preferred sensitizers.

For example, a preferred class of ketone sensitizers has the formula ACO(X) _b B, where X is ^CO or ^CR5R6 , where ^R5 and ^R6 may be the same or different and may be hydrogen, alkyl, alkaryl, or aralkyl, b is 0 or 1, and A and B are different and may be substituted (with one or more non-interfering substituents), the same or unsubstituted aryl, alkyl, alkaryl, or aralkyl groups, or A and B may together form a ring structure which may be a substituted or unsubstituted alicyclic, aromatic, heteroaromatic, or fused aromatic ring.

Suitable ketones of the above formula include monoketones (b=0), such as 2,2-, 4,4-, or 2,4-dihydroxybenzophenone, di-2-pyridyl ketone, di-2-furanyl ketone, di-2-thiophenyl ketone, benzoin, fluorenone, chalcone, Michler's ketone, 2-fluoro-9-fluorenone, 2-chlorothioxanthone, acetophenone, benzophenone, 1- or 2-acetonaphthone, 9-acetylanthracene, 2-, 3-, or 9-acetylphenanthrene, 4-acetylbiphenyl, propiophenone, n-butyrophenone, valerophenone, 2-, 3-, or 4-acetylpyridine, and 3-acetylcoumarin. Suitable diketones include aralkyl diketones such as anthraquinone, phenanthrenequinone, o-, m- and p-diacetylbenzene, 1,3-, 1,4-, 1,5-, 1,6-, 1,7- and 1,8-diacetylnaphthalene, 1,5-, 1,8- and 9,10-diacetylanthracene, and the like. Suitable alpha-diketones (b=1 and X=CO) include 2,3-butanedione, 2,3-pentanedione, 2,3-hexanedione, 3,4-hexanedione, 2,3-heptanedione, 3,4-heptanedione, 2,3-octanedione, 4,5-octanedione, benzyl, 2,2'-3,3'- and 4,4'-dihydroxybenzyl, furyl, di-3,3'-indolylethanedione, 2,3-bornanedione (camphorquinone), biacetyl, 1,2-cyclohexanedione, 1,2-naphthaquinone, and the like.

The third component of a ternary initiator system is a donor.

Preferred donors include, for example, amines (including aminoaldehydes and aminosilanes), amides (including phosphoramides), ethers (including thioethers), ureas (including thioureas), ferrocene, sulfinic acids and their salts, ferrocyanide salts, ascorbic acid and its salts, dithiocarbamic acids and their salts, xanthate salts, ethylenediaminetetraacetic acid salts, and tetraphenylboronic acid salts. Donors may be unsubstituted or substituted with one or more non-interfering substituents. Particularly preferred donors contain an electron donor atom, such as a nitrogen, oxygen, phosphorus, or sulfur atom, and an abstractable hydrogen atom bonded to a carbon or silicon atom alpha to the electron donor atom. Various types of donors are disclosed in U.S. Pat. No. 5,545,676 (Palazzotto et al.).

Alternatively, free radical initiators that can be used include the classes of acylphosphine oxides and bisacylphosphine oxides.

Suitable acylphosphine oxides have the general formula:
(R ⁹ )2-P(=O)-C(=O)-R ¹⁰
wherein each R ⁹ can individually be a hydrocarbyl group such as alkyl, cycloalkyl, aryl, and aralkyl, any of which may be substituted with a halo, alkyl, or alkoxy group, or two R ⁹ groups can combine to form a ring with the phosphorus atom; and R ¹⁰ is a hydrocarbyl group, an S-, O-, or N-containing 5- or 6-membered heterocyclic group, or a -Z-C(═O)-P(═O)-(R ⁹ ) ₂ group, where Z represents a divalent hydrocarbyl group such as alkylene or phenylene having 2 to 6 carbon atoms.
This can be explained by:

Preferred acylphosphine oxides are those in which the ^R9 and ^R10 groups are phenyl or lower alkyl or lower alkoxy substituted phenyl. "Lower alkyl" and "lower alkoxy" refer to such groups having 1 to 4 carbon atoms. Examples can also be found, for example, in U.S. Pat. No. 4,737,593.

Examples include bis-(2,6-dichlorobenzoyl)phenylphosphine oxide, bis-(2,6-dichlorobenzoyl)-2,5-dimethylphenylphosphine oxide, bis-(2,6-dichlorobenzoyl)-4-ethoxyphenyl-phosphine oxide, bis-(2,6-dichlorobenzoyl)-4-biphenylylphosphine oxide, bis-(2,6-dichlorobenzoyl)-4-propylphenylphosphine oxide, bis-(2,6-dichlorobenzoyl)-2-naphthylphosphine oxide, bis-(2,6-dichlorobenzoyl)-1-naphthylphosphine oxide, Bis-(2,6-dichlorobenzoyl)-4-chlorophenylphosphine oxide, bis-(2,6-dichlorobenzoyl)-2,4-dimethoxyphenylphosphine oxide, bis-(2,6-dichlorobenzoyl)decylphosphine oxide, bis-(2,6-dichlorobenzoyl)-4-octylphenylphosphine oxide, bis-(2,6-dimethoxybenzoyl)-2,5-dimethylphenylphosphine oxide, bis-(2,6-dimethoxybenzoyl)-phenylphosphine oxide, bis-(2,4,6-trimethylbenzoyl)-2,5-dimethylphenylphosphine oxide Cide, bis-(2,6-dichloro-3,4,5-trimethoxybenzoyl)-2,5-dimethylphenylphosphine oxide, bis-(2,6-dichloro-3,4,5-trimethoxybenzoyl)-4-ethoxyphenylphosphine oxide, bis-(2-methyl-1-naphthoyl)-2,5-dimethylphenylphosphine oxide, bis-(2-methyl-1-naphthoyl)phenylphosphine oxide, bis-(2-methyl-1-naphthoyl)-4-biphenylylphosphine oxide, bis-(2-methyl-1-naphthoyl)-4-ethoxyphenylphosphine oxide, bis-(2-methyl Examples of such compounds include bis-(2-methyl-1-naphthoyl)-2-naphthylphosphine oxide, bis-(2-methyl-1-naphthoyl)-4-propylphenylphosphine oxide, bis-(2-methyl-1-naphthoyl)-2,5-dimethylphosphine oxide, bis-(2-methoxy-1-naphthoyl)-4-ethoxyphenylphosphine oxide, bis-(2-methoxy-1-naphthoyl)-4-biphenylylphosphine oxide, bis-(2-methoxy-1-naphthoyl)-2-naphthylphosphine oxide, and bis-(2-chloro-1-naphthoyl)-2,5-dimethylphenylphosphine oxide.

A tertiary amine reducing agent may be used in combination with an acylphosphine oxide. Exemplary tertiary amines useful in the present invention include ethyl 4-(N,N-dimethylamino)benzoate and N,N-dimethylaminoethyl methacrylate.

Commercially available phosphine oxide photoinitiators capable of free radical initiation when irradiated with wavelengths greater than 400 nm to 1,200 nm include a 25:75 by weight mixture of bis(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide and 2-hydroxy-2-methyl-1-phenylpropan-1-one (formerly known as Irgacure™ 1700, Ciba), 2-benzyl-2-(N,N-dimethylamino)-1-(4-morpholinophenyl)-1-butanone (formerly known as Irgacure™ 369, Ciba), and bis(η5-2,4-cyclopentadien-1-yl)-bis(2,6-difluoro-3-(1H-pyrrolidone)). Examples of suitable bis(2,4,6-trimethylbenzoyl)phenyl titanium (formerly known as Irgacure™ 784DC, Ciba), a 1:1 by weight mixture of bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide and 2-hydroxy-2-methyl-1-phenylpropan-1-one (formerly known as Darocur™ 4265, Ciba), ethyl-2,4,6-trimethylbenzylphenylphosphine oxide (formerly known as Lucirin™ LR8893X, BASF), and bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide (formerly known as Irgacure™ 819, BASF).

Another free radical initiator system that can alternatively be used is the class of ionic dye counterion complex initiators that contain a borate anion and a complementary cationic dye.

Borate salt photoinitiators are described, for example, in U.S. 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 5,057,393 (Shanklin et al.).

Borate anions useful in these photoinitiators ^can generally ^{be of} the formula ^R1R2R3R4B- , where ^R1 , ^R2 , ^R3 , and ^R4 can independently be alkyl, ^aryl , alkaryl, aryl, aralkyl, alkenyl, alkynyl, alicyclic, and saturated or unsaturated heterocyclic groups. Preferably, ^R2 , ^R3 , and ^R4 are aryl groups, more preferably phenyl groups, and ^R1 is an alkyl group, more preferably a secondary alkyl group.

Cationic counterions can be cationic dyes, quaternary ammonium groups, transition metal coordination complexes, and the like. Cationic dyes useful as counterions can be cationic methine, polymethine, triarylmethine, indoline, thiazine, xanthene, oxazine, or acridine dyes. More specifically, dyes can be cationic cyanine, carbocyanine, hemicyanine, rhodamine, and azomethine dyes. Specific examples of useful cationic dyes include methylene blue, safranine O, and malachite green. Quaternary ammonium groups useful as counterions can be trimethylcetylammonium, cetylpyridinium, and tetramethylammonium. Other organophilic cations can include pyridinium, phosphonium, and sulfonium.

Photosensitive transition metal coordination complexes that can be used include complexes of cobalt, ruthenium, osmium, zinc, iron, and iridium with ligands such as pyridine, 2,2'-bipyridine, 4,4'-dimethyl-2,2'-bipyridine, 1,10-phenanthroline, 3,4,7,8-tetramethylphenanthroline, 2,4,6-tri(2-pyridyl-s-triazine), and related ligands.

In a further alternative, heat may be used to initiate solidification or polymerization of the free radically active groups.

Examples of heat sources suitable for the dental materials of the present invention include inductive, convective, and radiative heat sources. The heat source should be capable of generating temperatures of at least 40°C to 15°C under normal conditions or at elevated pressure.

A thermal curing procedure is sometimes preferred to initiate polymerization of the material outside the oral environment, for example, when the composition is used to manufacture mill blanks, or in a post-cure step of an article obtained by processing the composition as a resin in an additive manufacturing process.

The components of the photoinitiator system are typically present in an amount of at least 0.1 wt%, or 0.2 wt%, or 0.3 wt%, and up to 4 wt%, or 3 wt%, or 2 wt%, and in an amount ranging from 0.1 wt% to 4 wt%, or 0.2 wt% to 3 wt%, or 0.3 wt% to 2 wt%, where the weight percentages are based on the dental composition.

Alternatively, or in addition, the dental composition can be hardened by using a redox initiator system.

Initiators that rely on redox reactions are often called "self-cure catalysts" or "dark-cure catalysts." To avoid premature hardening of the dental composition, the two main components of the system (oxidizer and reducer) should be kept separate during storage of the dental composition.

The oxidizing agent typically used is a peroxy component such as a peroxide. Organic peroxides that can be used include diperoxides and hydroperoxides.

According to one embodiment, the organic peroxide is a di-peroxide, preferably comprising the moiety R ₁ -O-O-R ₂ -O-O-R ₃ , where R ₁ and R ₃ are independently selected from H, alkyl (e.g., C ₁ to C ₆ ), branched alkyl (e.g., C ₁ to C ₆ ), cycloalkyl (e.g., C ₅ to C ₁₀ ), alkylaryl (e.g., C ₇ to C ₁₂ ), or aryl (e.g., C ₆ to C ₁₀ ), and R ₂ is selected from alkyl (e.g., C ₁ to C ₆ ), or branched alkyl (e.g., C ₁ to C ₆ ).

Examples of suitable organic di-peroxides include 2,2-di-(tert-butylperoxy)-butane and 2,5-dimethyl-2,5-di-(tert-butylperoxy)-hexane, and mixtures thereof.

According to another embodiment, the organic peroxide is a hydroperoxide, particularly one having the structural moiety:
R-O-O-H
wherein R is (e.g., C ₁ -C ₂₀ ) alkyl, (e.g., C ₃ -C ₂₀ ) branched alkyl, (e.g., C ₆ -C ₁₂ ) cycloalkyl, (e.g., C ₇ -C ₂₀ ), alkylaryl (e.g., C ₆ -C ₁₂ ), or aryl (e.g., C ₆ -C ₁₂ ).
is a hydroperoxide containing

Examples of suitable organic hydroperoxides include t-butyl hydroperoxide, t-amyl hydroperoxide, p-diisopropylbenzene hydroperoxide, cumene hydroperoxide, pinane hydroperoxide, p-methane hydroperoxide, and 1,1,3,3-tetramethylbutyl hydroperoxide, and mixtures thereof.

The use of hydroperoxides is sometimes preferred, especially for formulating self-adhesive compositions.

Other peroxides that can be used are ketone peroxides, diacyl peroxides, dialkyl peroxides, peroxyketals, peroxyesters, and peroxydicarbonates.

Ketone peroxides include methyl ethyl ketone peroxide, methyl isobutyl ketone peroxide, methyl cyclohexanone peroxide, and cyclohexanone peroxide.

Examples of peroxyesters include alpha-cumyl peroxyneodecanoate, t-butyl peroxypivalate, t-butyl peroxyneodecanoate, 2,2,4-trimethylpentylperoxy-2-ethylhexanoate, t-amyl peroxy-2-ethylhexanoate, t-butyl peroxy-2-ethylhexanoate, di-t-butylperoxyisophthalate, di-t-butylperoxyhexahydroterephthalate, t-butylperoxy-3,3,5-trimethylhexanoate (t-butylperoxy-3,3,5-trimethylhexanoate, TBPIN), t-butyl peroxyacetate, t-butyl peroxybenzoate, and t-butyl peroxymaleate.

Examples of peroxydicarbonates include di-3-methoxyperoxydicarbonate, di-2-ethylhexyl peroxydicarbonate, bis(4-t-butylcyclohexyl) peroxydicarbonate, diisopropyl-1-peroxydicarbonate, di-n-propyl peroxydicarbonate, di-2-ethoxyethyl peroxydicarbonate, and diallyl peroxydicarbonate.

Examples of diacyl peroxides include acetyl peroxide, benzoyl peroxide, decanoyl peroxide, 3,3,5-trimethylhexanoyl peroxide, 2,4-dichlorobenzoyl peroxide, and lauroyl peroxide.

Examples of dialkyl peroxides include di-t-butyl peroxide, dicumyl peroxide, t-butylcumyl peroxide, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane, 1,3-bis(t-butylperoxyisopropyl)benzene, and 2,5-dimethyl-2,5-di(t-butylperoxy)-3-hexane.

Examples of peroxyketals include 1,1-bis(t-butylperoxy)-3,3,5-trimethylcyclohexane, 1,1-bis(t-butylperoxy)cyclohexane, 2,2-bis(t-butylperoxy)butane, 2,2-bis(t-butylperoxy)octane, and 4,4-bis(t-butylperoxy)valeric acid-n-butyl ester.

When a peroxy component is present, it is typically present in an amount of 0.1% to 5% by weight, or 0.25% to 4% by weight, of the dental composition.

In addition to the peroxide component, further oxidizing components, such as persulfate components, particularly water-soluble persulfate components, may be present.

Persulfates that may be used can _{be characterized by the formula D2S2O8 ,} where D is selected from Li, Na, K, _NH4 , _NR4 , _and R is selected from _{H and CH3} . Examples of _persulfates that may be used include _Na2S2O8 , _K2S2O8 , _{( NH4} ) _{2S2O8 ,} and mixtures thereof.

When a persulfate component is present, it is typically present in an amount of 0.1% to 5% by weight, or 0.25% to 4% by weight.

Barbituric acid or thiobarbituric acid components, particularly their respective salts, can be used as reducing agents. Suitable barbituric acid components have the following formula:

wherein R1, R2, and R3 are independently selected from hydrogen, alkyl, substituted alkyl, alkenyl, cycloalkyl, substituted cycloalkyl, arylalkyl, aryl, or substituted aryl; X is oxygen or sulfur; and Y is a metal cation or an organic cation.
can be characterized by

The salt may comprise a metal cation or an inorganic cation. Suitable metal cations include any metal M that can provide a stable cation M ⁺ , M2 ⁺ , or M3 ⁺ . Some possible inorganic cations include cations of Li, Na, K, Mg, Ca, Sr, Ba, Al, Fe, Cu, Zn, or La.

Examples of suitable barbituric acid or thiobarbituric acid components include barbituric acid, thiobarbituric acid, 1,3,5-trimethylbarbituric acid, 1-phenyl-5-benzylbarbituric acid, 1-benzyl-5-phenylbarbituric acid, 1,3-dimethylbarbituric acid, 1,3-dimethyl-5-phenylbarbituric acid, 1-cyclohexyl-5-ethylbarbituric acid, 5-laurylbarbituric acid, 5-butylbarbituric acid, 5-allylbarbituric acid, 5-phenylthiobarbituric acid, 1,3-dimethylthiobarbituric acid, trichlorobarbituric acid, 5-nitrobarbituric acid, 5-aminobarbituric acid, and 5-hydroxybarbituric acid.

An exemplary salt is the calcium salt of 1-benzyl-5-phenyl-barbituric acid. Another example of a suitable barbituric acid salt is the sodium salt of 1-benzyl-5-phenyl-barbituric acid. A possible salt is the calcium salt of 5-phenyl-thiobarbituric acid.

The salt may also contain an organic cation. Suitable possible organic cations include amine cations, such as ammonium cations or alkylammonium cations. One example is the triethanolammonium salt of 1-benzyl-5-phenyl-barbituric acid.

When present, the barbituric acid or thiobarbituric acid component is typically present in an amount of 0.1% to 3%, or 0.5% to 2%, by weight of the dental composition.

Other reducing agents that can be used include aromatic sulfinates or thiourea moieties.

Suitable sulfinic acid components have the formula:
R ¹ SOO-R ²
wherein R ¹ is an alkyl, substituted alkyl, alkenyl, cycloalkyl, substituted cycloalkyl, arylalkyl, aryl, or substituted aryl group; and R ² = H, a metal such as lithium, sodium, or potassium, or an alkyl, substituted alkyl, alkenyl, cycloalkyl, substituted cycloalkyl, arylalkyl, aryl, or substituted aryl group.
can have:

When one of the groups ^R1 or ^R2 is unsubstituted alkyl, this group can be straight-chain or branched and can contain, for example, 1 to 18 carbon atoms, preferably 1 to 10, especially 1 to 6 carbon atoms. Examples of low-molecular alkyl groups are methyl, ethyl, propyl, isopropyl, n-butyl, t-butyl, isobutyl, n-pentyl, and isoamyl.

When one of the groups ^R1 or ^R2 is a substituted alkyl group, the alkyl portion of this group typically has the number of carbon atoms indicated above for unsubstituted alkyl. When one of the groups ^R1 or ^R2 is an alkoxyalkyl or alkoxycarbonylalkyl, the alkoxy group contains, for example, 1 to 5 carbon atoms and is preferably methyl, ethyl, propyl, isopropyl, n-butyl, t-butyl, isobutyl, n-pentyl, or isoamyl. When one of the groups ^R1 or ^R2 is a haloalkyl, the halo moiety is understood to be fluoro, chloro, bromo, or iodo.

When one of the groups ^R1 or ^R2 is alkenyl, it is typically a _C3 - _C5 alkenyl group, especially allyl. When one of the groups ^R1 or ^R2 is unsubstituted cycloalkyl, it is typically a _C4 - _C7 cycloalkyl group such as cyclopentyl or cyclohexyl. When one of the groups ^R1 or ^R2 is substituted cycloalkyl, it is typically one of the cycloalkyl groups mentioned above, and the substituents on the cycloalkyl group may be, for example, _C1 - _C4 alkyl, such as methyl, ethyl, propyl, n-butyl or isobutyl, fluoro, chloro, bromo, iodo, or _C1 - _C4 alkoxy, especially methoxy. When one of the groups ^R1 or ^R2 is aryl or aralkyl, it is typically phenyl or naphthyl as aryl. Preferred arylalkyl groups include benzyl and phenylethyl.

^R1 or ^R2 may optionally be a substituted aryl group, of which phenyl and naphthyl are preferred, with ring substituents being _C1 - _C4 alkyl, especially methyl, halogen, or _C1 - _C4 alkoxy, especially methoxy.

In particular, the following components have been found to be useful: benzenesulfinic acid, sodium benzenesulfinate, sodium benzenesulfinate dihydrate, sodium toluenesulfinate, formamidinesulfinic acid, the sodium salt of hydroxymethanesulfinic acid, the sodium salt of 2,5-dichlorobenzenesulfinic acid, and 3-acetamido-4-methoxybenzenesulfinic acid, with sodium toluenesulfinate or sodium benzenesulfinate and their hydrates sometimes being preferred.

When a sulfinic acid component is present, it is typically present in an amount of 0.1% to 3% by weight, or 0.5% to 2% by weight, of the dental cement composition.

Suitable thiourea components include 1-ethyl-2-thiourea, tetraethylthiourea, tetramethylthiourea, 1,1-dibutylthiourea, and 1,3-dibutylthiourea, and mixtures thereof.

If desired, the dental cement composition may contain a combination or mixture of different reducing agents, including a combination of a barbituric acid component and a sulfinic acid component.

In addition to the above components, the redox initiator system may also include an activator.

Suitable activators include tertiary aromatic amines, such as N,N-bis-(hydroxyalkyl)-3,5-xylidine (e.g., those described in U.S. Pat. No. 3,541,068), as well as N,N-bis-(hydroxyalkyl)-3,5-di-t-butylaniline, particularly N,N-bis-([beta]-oxybutyl)-3,5-di-t-butylaniline, and N,N-bis-(hydroxyalkyl)-3,4,5-trimethylaniline.

Optionally, and for promotion, the polymerization can be carried out in the presence of a transition metal component. Suitable transition metal components include organic and/or inorganic salts of vanadium, chromium, manganese, iron, cobalt, nickel, and/or copper, with copper, iron, and vanadium sometimes being preferred.

According to one embodiment, the transition metal component is a copper-containing component. The oxidation state of the copper in the copper-containing component is preferably +1 or +2.

Typical examples of copper components that can be used include copper salts and complexes, including copper acetate, copper chloride, copper benzoate, copper acetylacetonate, copper naphthenate, copper carboxylate, copper bis(1-phenylpentane-1,3-dione) complex (copper propionate), copper ethylhexanoate, copper salicylate, copper thiourea complex, ethylenediaminetetraacetic acid, and/or mixtures thereof. The copper compounds can be used in hydrated or water-free form.

Particularly preferred are sometimes copper(II) acetate, copper bis(1-phenylpentane-1,3-dione) complex (copper propionate), and copper ethylhexanoate.

According to one embodiment, the transition metal component is an iron-containing component. The oxidation state of the iron in the iron-containing component is preferably +2 or +3.

Typical examples of iron-containing components that can be used include iron salts and complexes, including iron(III) sulfate, iron(III) chloride, iron carboxylate, iron naphthenate, and iron(III) acetylacetonate, as well as hydrates of these salts.

According to one embodiment, the transition metal component is a vanadium-containing component. The oxidation state of the vanadium in the vanadium-containing component is preferably +4 or +5.

Typical examples of vanadium components that can be used include vanadium salts and complexes, including vanadium acetylacetonate, vanadyl acetylacetonate, vanadyl stearate, vanadium naphthenate, vanadium benzoylacetonate, vanadyl oxalate, bis(maltolato)oxovanadium(IV), oxobis(1-phenyl-1,3-butanedionato)vanadium(IV), vanadium(V)oxytriisopropoxide, ammonium(V) metavanadate, sodium(V) metavanadate, vanadium pentoxide(V), divanadium tetraoxide(IV), and vanadyl(IV) sulfate, and mixtures thereof, with vanadium acetylacetonate, vanadyl acetylacetonate, and bis(maltolato)oxovanadium(IV) being sometimes preferred.

Suitable redox initiator systems are also described in U.S. Patent Application Publication Nos. 2003/008967(A1) (Hecht et al.), 2004/097613(A1) (Hecht et al.), and 2019/000721(A1) (Ludsteck et al.), the contents of which are incorporated herein by reference.

The composition may contain suitable adjuvants or additives such as surfactants, rheology modifiers, retarders, stabilizers, pigments, dyes, photobleachable colorants, fluoride release agents, solvents, and other elements known to those skilled in the art.

Surfactants that can be added include polyethylene glycol-modified siloxanes (e.g., Silwet™-type surfactants available from Momentive) and polyethylene glycol-modified carbosilanes (e.g., as described in U.S. Pat. No. 5,750,589 (Zech et al.)).

Rheology modifiers that can be added include surface-modified fumed silica, organophilic phyllosilicates, modified ureas, polyhydroxycarboxylic acid amides (e.g., Rheobyk™ types available from Byk-Chemie, Wesel, Germany), dibenzylidene sorbitol, and diamides (e.g., Thixatrol™ types available from Elementis, East Windsor, New Jersey, USA) as described above.

Retarders that can be added include 1,2-diphenylethylene and its derivatives.

Stabilizers that can be used include, in particular, free radical scavengers, such as substituted and/or unsubstituted hydroxyaromatic compounds (e.g., butylated hydroxytoluene (BHT), hydroquinone, hydroquinone monomethyl ether, etc.). ether, MEHQ), 3,5-di-tert-butyl-4-hydroxyanisole (2,6-di-tert-butyl-4-ethoxyphenol), 2,6-di-tert-butyl-4-(dimethylamino)methylphenol or 2,5-di-tert-butylhydroquinone, 2-(2'-hydroxy-5'-methylphenyl)-2H-benzotriazole, 2-(2'-hydroxy-5'-t-octylphenyl)-2H-benzotriazole, 2-hydroxy-4-methoxybenzophenone (UV-9), 2-(2'-hydroxy-4',6'-di-tert-pentylphenyl)-2H-benzotriazole, 2-hydroxy-4-n-octoxybenzophenone, 2-(2'-hydroxy-5'-methacryloxyethylphenyl)-2H-benzotriazole, phenothiazine, and HALS (hindered amine light stabilizer) (hindered amine light stabilizer).

Pigments and/or dyes that can be used include titanium dioxide or zinc sulfide (lithopone), red iron oxide 3395, Bayferrox™ 920Z Yellow, Neazopon™ Blue 807 (a copper phthalocyanine pigment), or Helio™ Fast Yellow ER. These additives can be used to individually color the composition.

Examples of photobleachable colorants include rose bengal, methylene violet, methylene blue, fluorescein, eosin yellow, eosin Y, ethyl eosin, eosin blueish, eosin B, erythrosin B, erythrosin yellowish blend, toluidine blue, 4',5'-dibromofluorescein, and blends thereof. Further examples of photobleachable colorants can be found in U.S. Pat. No. 6,444,725 (Trom et al.).

Examples of fluoride-releasing agents include naturally occurring or synthetic fluoride minerals. These fluoride sources can optionally be treated with a surface treatment agent.

Solvents that may be present include linear, branched, or cyclic, saturated or unsaturated alcohols, ketones, esters, ethers, or mixtures of two or more of these types of solvents, each having 2 to 10 carbon atoms. Preferred alcohol solvents include methanol, ethanol, isopropanol, and n-propanol. Other suitable organic solvents are THF, acetone, methyl ethyl ketone, cyclohexanol, toluene, alkanes, and alkyl acetates, especially ethyl acetate.

These additives need not be present, and therefore may not be present at all. However, if present, they are typically present in amounts that are not deleterious to the intended purpose.

Additives are typically present in an amount of at least 0%, 0.01%, or 0.1% by weight, up to 20%, 15%, or 10% by weight, in an amount ranging from 0% to 20%, 0.01% to 15%, or 0.1% to 10% by weight, where the weight percentages are based on the dental composition.

The dental composition comprises the following components:
a. a surface-treated filler, particularly in an amount of 40% to 80% by weight;
b. a curable component, particularly in an amount of 5% to 50% by weight;
c. an initiator system suitable for curing the curable component, particularly in an amount of 0.1% to 5% by weight;
d. additives, especially in an amount of 0% to 10% by weight, and
The weight percentages are based on the weight of the dental composition.

The dental compositions described herein are typically prepared by combining or mixing the respective components, i.e., the polymerizable component of the resin matrix, the filler, and the initiator component, along with other optional components such as additives. Usually, the resin matrix is provided first, and the filler is added later.

Optionally, a speed mixer can be used. Depending on the ingredients being mixed, mixing is carried out under light-saving conditions. Mixing also includes kneading. Optionally, a vacuum can be applied during or at the end of mixing to remove air introduced during mixing or kneading.

The dental compositions described herein are typically for use in a method of restoring a tooth in the mouth of a mammal, wherein the dental composition is as described herein and the method comprises the steps of:
a) contacting a dental composition with the tooth surface to be restored;
b) hardening the dental composition by applying radiation.

More specifically, the method comprises the steps of:
a) applying a dental composition to the surface of dental hard tissue, which can be an etched surface (e.g., with phosphoric acid) or an unetched surface, as desired;
b) optionally dispersing the dental composition into a thin film, preferably using an air stream;
c) Radiation curing the dental composition.

A dental curing light is typically used for the curing process. The radiation usually has a wavelength in the range of 400 nm to 800 nm and is applied for a time in the range of 5 seconds to 1 minute.

The dental composition is particularly useful in the fields of dentistry and orthodontics. The dental composition can be used as or to make dental restorations.

Examples of dental restorations include direct restorative materials (e.g., anterior and posterior restorations), prostheses, veneers, artificial crowns, artificial teeth, dentures, etc.

As used herein, the term "prosthesis" refers to a composite that is shaped and polymerized for its end use (e.g., as a crown, bridge, veneer, inlay, onlay, etc.) before being placed adjacent to a tooth.

When the dental material is applied to a tooth, the tooth may optionally be pretreated with a primer, such as a dentin adhesive or enamel adhesive, by methods known to those skilled in the art.

In particular, the dental composition can be used as a composite filling material, a cavity liner, or a fixing material for orthodontic appliances.

The term "composite filling material" refers to a dental composition that is filled. Dental composite materials are typically used to restore defective tooth structure in a patient's mouth.

"Cavity liner" means a composition for protecting the dental pulp before a composite filling material or dental restoration is applied.

In a preferred embodiment, the dental material is a low-viscosity dental filling material.

A further aspect of the present invention is directed to the use of the surface-treated filler described herein to reduce the viscosity of a dental composition comprising a hardenable component and a filler in an amount of 40 to 80 weight percent, based on the weight of the dental composition.

The surface-treated fillers are particularly useful for producing hardenable dental compositions having a filler content of 40% to 80% by weight and a viscosity of 5 Pa ^* s to 1,500 Pa ^* s at 25°C and a shear rate of 0.01 s ^-1 in the absence of a rheology modifier.

In a further aspect, the present invention relates to the following embodiments:
Embodiment 1
1. A dental composition comprising:
a filler in an amount of 40% to 80% by weight;
a curable composition in an amount of 5% to 50% by weight, the curable composition being selected from a polymerizable component that includes an acidic moiety, a polymerizable component that does not include an acidic moiety, and mixtures thereof;
an initiator system suitable for curing the curable component in an amount of 0.1 wt. % to 5 wt. %, the initiator system comprising a photoinitiator system and/or a redox initiator system;
additives in an amount of 0% to 10% by weight; and
The weight percentages are based on the weight of the dental composition;
The surface treatment agent has the following properties:
containing only one (meth)acrylate moiety;
containing at least one tri-methoxysilane or tri-ethoxysilane moiety;
containing only one urethane moiety;
comprising one linear alkylene moiety AM1 linking the (meth)acrylate moiety to the urethane moiety, the linear alkylene moiety AM1 comprising 6 to 12 C atoms,
characterised in that it comprises one linear alkylene moiety AM2 linking at least one tri-methoxysilane or tri-ethoxysilane moiety to a urethane moiety, the linear alkylene moiety AM2 comprising 1 to 4 C atoms,
Dental compositions.

Embodiment 2
1. A dental composition comprising:
a surface-treated filler in an amount of 40% to 80% by weight, wherein the filler particles are selected from non-aggregated, non-agglomerated nano-sized particles of _SiO2 , _ZrO2 or mixtures thereof, aggregated nano-sized particles of _SiO2 , _ZrO2 or mixtures thereof _, agglomerated nano-sized particles of _SiO2 , _ZrO2 , _Al2O3 or mixtures thereof, non-acid-reactive particles of glass, silica, metal oxides or mixtures thereof, acid-reactive particles of glass, metal oxides and hydroxides or mixtures thereof;
a curable composition in an amount of 5% to 50% by weight, the curable composition being selected from a polymerizable component that includes an acidic moiety, a polymerizable component that does not include an acidic moiety, and mixtures thereof;
an initiator system suitable for curing the curable component in an amount of 0.1 wt. % to 5 wt. %, the initiator system comprising a photoinitiator system and/or a redox initiator system;
additives in an amount of 0% to 10% by weight; and
The weight percentages are based on the weight of the dental composition;
The surface treatment agent has the following properties:
containing only one (meth)acrylate moiety;
containing at least one tri-methoxysilane or tri-ethoxysilane moiety;
containing only one urethane moiety;
comprising one linear alkylene moiety AM1 linking the (meth)acrylate moiety to the urethane moiety, the linear alkylene moiety AM1 comprising 6 to 12 C atoms,
characterised in that it comprises one linear alkylene moiety AM2 linking at least one tri-methoxysilane or tri-ethoxysilane moiety to a urethane moiety, the linear alkylene moiety AM2 comprising 1 to 4 C atoms,
Dental compositions.

Embodiment 3
1. A dental composition comprising:
a filler in an amount of 40% to 80% by weight;
a curable composition in an amount of 5% to 50% by weight, the curable composition being selected from a polymerizable component that includes an acidic moiety, a polymerizable component that does not include an acidic moiety, and mixtures thereof;
an initiator system suitable for curing the curable component in an amount of 0.1 wt. % to 5 wt. %, the initiator system comprising a photoinitiator system and/or a redox initiator system;
additives in an amount of 0% to 10% by weight; and
The weight percentages are based on the weight of the dental composition;
The surface treatment agent is represented by the following formula:
H ₂ C=CHR ¹ -CO-O-(CH ₂ ) _n -X-CO-Y-(CH ₂ ) _m -Si(R ² ) _o (R ³ ) _3-o
wherein R ¹ =H or CH ₃ , R ² =Cl, Br, O—C _1-4 alkyl, O—C _1-4 acyl, R ³ =C _1-4 alkyl, X=O, Y=NH, n=6-12, m=1-4, o=1-3.
characterized by,
Dental compositions.

Embodiment 4
1. A dental composition comprising:
a surface-treated filler in an amount of 40% to 80% by weight, wherein the filler particles are selected from aggregated nano-sized particles of SiO ₂ , ZrO ₂ or mixtures thereof, agglomerated nano-sized particles of SiO ₂ , ZrO ₂ , Al ₂ O ₃ or mixtures thereof;
a curable composition in an amount of 5% to 50% by weight, the curable composition being selected from a polymerizable component that includes an acidic moiety, a polymerizable component that does not include an acidic moiety, and mixtures thereof;
an initiator system suitable for curing the curable component in an amount of 0.1 wt. % to 5 wt. %, the initiator system comprising a photoinitiator system and/or a redox initiator system;
additives in an amount of 0% to 10% by weight; and
The weight percentages are based on the weight of the dental composition;
The surface treatment agent has the following properties:
containing only one (meth)acrylate moiety;
containing at least one tri-methoxysilane or tri-ethoxysilane moiety;
containing only one urethane moiety;
comprising one linear alkylene moiety AM1 linking the (meth)acrylate moiety to the urethane moiety, the linear alkylene moiety AM1 comprising 6 to 12 C atoms,
characterised in that it comprises one linear alkylene moiety AM2 linking at least one tri-methoxysilane or tri-ethoxysilane moiety to a urethane moiety, the linear alkylene moiety AM2 comprising 1 to 4 C atoms,
Dental compositions.

The dental compositions described herein typically do not contain bisphenol-A-glycidyl methacrylate (Bis-GMA), particularly not in an amount greater than or equal to 1% by weight based on the weight of the dental composition. Thus, this component is typically not present and/or not intentionally added.

Dental compositions are typically provided to practitioners under hygienic conditions. During storage, the compositions are typically packaged in suitable packaging and/or delivery devices.

One possibility for achieving this involves packaging or containing the composition in a sealed container. A suitable container may have a front end and a back end, a piston movable within the container, and a nozzle or cannula for delivering or dispensing the composition disposed within the container. The container usually has only one compartment or reservoir. The volume of the container typically ranges from 0.1 mL to 100 mL, or from 0.5 mL to 50 mL, or from 1 mL to 30 mL.

Suitable single-use containers may have a volume ranging from 0.05 mL to 1 mL, which is the volume typically required for a single application procedure. Such containers are typically used only once (e.g., disposable packaging).

The composition can be dispensed from the container by moving the piston toward the nozzle. The piston can be moved manually or with the assistance of an application device or implement designed to receive the container (e.g., an application device having the design of a caulking gun).

Examples of containers that can be used include capsules, syringes, and screw tubes.

A compule typically has a cylindrical housing with a front end and a rear end, and a nozzle. The rear end of the housing is usually sealed with a movable piston. Typically, the dental composition is dispensed from the compule or container using an application tool with a movable plunger (e.g., an application device in the shape of a caulking gun).

Examples of suitable compules or containers are described in U.S. Pat. No. 5,624,260 (Wilcox et al.), European Patent Application Publication No. 1,340,472 (A1) (Centrix), U.S. Pat. Application Publication No. 2007/0172789 (A1) (Mueller et al.), and U.S. Pat. No. 5,865,803 (Major). Further suitable containers are exemplified in U.S. Pat. No. 5,927,562 (Hammen et al.) and U.S. Pat. Application Publication No. 2011/151403 (A1) (Pauser et al.).

It may be advantageous if a container is used that has a nozzle shaped and sized to allow for easy and safe application of the composition to the dental soft tissue surrounding the tooth to be restored, as well as to the interdental areas.

The smaller the nozzle diameter, the easier it is to place the nozzle in the area between two teeth. However, a smaller nozzle diameter may require a greater extrusion force to dispense the composition from the device. Therefore, not all cannula sizes and diameters are equally suitable. Devices with nozzles or cannulas having an outer diameter in the range of 0.6 mm to 1.3 mm and an inner diameter in the range of 0.2 mm to 0.9 mm have been found to be particularly useful.

Flowable dental composite materials are often stored in packaging material shaped like a syringe.

The packaging device may include two compartments, each with a nozzle for delivering the composition or parts stored therein. After delivery in appropriate amounts, the parts can then be mixed by hand on a mixing plate.

Two-compartment packaging devices are particularly suitable for storing and delivering two-part compositions, i.e., compositions that must be kept separate prior to use to avoid undesired polymerization. Two-part compositions are typically cured by a redox initiator system in which the oxidizing agent-containing part is kept separate from the reducing agent-containing part.

The packaging device may have an interface that accepts a static mixing tip. The mixing tip is used to mix the individual compositions.

The packaging device typically has two containers or compartments, each having a front end with a nozzle, a rear end, and at least one piston movable within the container or compartment.

Cartridges that can be used are also described, for example, in U.S. Patent Application Publication No. 2007/0090079 (A1) or U.S. Patent No. 5,918,772. Some cartridges that can be used are commercially available, for example, from SulzerMixpac (Switzerland).

Static mixing tips that can be used are described, for example, in U.S. Patent Application Publication No. 2006/0187752 (A1) or U.S. Patent No. 5,944,419, the disclosures of which are incorporated by reference. Mixing tips that can be used are also commercially available from Sulzer Mixpac (Switzerland).

Other suitable storage devices are described, for example, in WO 2010/123800 (A1) (3M), WO 2005/016783 (A1) (3M), WO 2007/104037 (A1) (3M), WO 2009/061884 (A1) (3M), in particular the device shown in Figure 14 of WO 2009/061884 (A1) (3M), or in WO 2015/073246 (A1) (3M), in particular the device shown in Figure 1 of WO 2015/07346 (A1). These storage devices have the shape of a syringe.

The present invention also relates to a kit of parts that includes the dental composition described herein and the following parts, alone or in combination: a dental adhesive, a dental curing light, and an application device.

Dental adhesives are typically acidic dental compositions with fairly low viscosities (e.g., 0.01 Pa ^* s to 3 Pa ^* s at 25°C). Dental adhesives interact directly with tooth enamel or dentin surfaces. Dental adhesives are typically one-part compositions, are radiation-curable, and include an ethylenically unsaturated component with an acidic moiety, an ethylenically unsaturated component without an acidic moiety, water, a sensitizer, a reducing agent, and additives.

Examples of dental adhesives are described in U.S. Patent Application Publication Nos. 2020/0069532(A1) (Thalacker et al.) and 2017/0065495(A1) (Eckert et al.). Dental adhesives are also commercially available, for example, 3M™ Scotchbond™ Universal (3M Oral Care).

Suitable dental curing lights are described in U.S. Pat. No. 10,758,126 (B2) (Geldmacher et al.) or U.S. Pat. No. 10,231,810 (B2) (Gramann et al.). Dental curing lights are also commercially available, such as the 3M™ Elipar™ S10 or 3M™ Elipar™ DeepCure S LED curing light (3M Oral Care).

Suitable application devices include, for example, brushes, spatulas, syringes, and other suitable devices known to those skilled in the art.

The complete disclosures of the patents, patent documents, and publications cited herein are incorporated by reference in their entireties, as if each were individually incorporated. Various modifications and variations of the present invention will be apparent to those skilled in the art without departing from the scope and spirit of the invention. The above specification, examples, and data provide a description of the manufacture and use of the compositions and methods of the present invention. The present invention is not limited to the embodiments disclosed herein. Those skilled in the art will recognize that many alternative embodiments of the present invention can be made without departing from the spirit and scope of the present invention.

The following examples are presented to illustrate the present invention.

Unless otherwise specified, all parts and percentages are by weight, all water is deionized, and all molecular weights are weight average molecular weight. Furthermore, unless otherwise specified, all experiments were conducted at ambient conditions (23°C, 1013 mbar).

Methods Viscosity Viscosity measurements were performed on a rheometer equipped with a plate-plate system (d=15 mm or 20 mm) using a gap of 0.2 mm at 25° C. and a ramp shear from 100/s to 0.008/s in 1 min.

Particle size distribution (suitable for micron-sized particles)
If desired, particle size distribution, including particle size per volume (d50), can be determined by laser diffraction using a Mastersizer 2000 (Malvern) particle size detection device, applying the Fraunhofer approximation. During measurement, ultrasound is typically used to accurately disperse the sample. For water-insoluble particles, water is typically used as a dispersant.

Particle size distribution (suitable for nano-sized particles)
Optionally, particle size measurements can be performed using a light scattering particle size analyzer (obtained under the trade designation "ZETA SIZER-Nano Series, Model ZEN3600" from Malvern Instruments Inc., Westborough, MA) equipped with a red laser having a light wavelength of 633 nm. Each sample is analyzed in a 1 cm square polystyrene sample cuvette. The sample is diluted 1:100, e.g., 1 g of sample is added to 100 g of deionized water and mixed. The sample cuvette is filled with approximately 1 gram of diluted sample. The sample cuvette is then placed in the instrument and allowed to equilibrate at 25°C. The instrument parameters are set as follows: dispersant refractive index 1.330, dispersant viscosity 0.8872 mPa ^* s, material refractive index 1.43, and material absorption value 0.00 units. The automated size measurement procedure is then performed. The instrument automatically adjusts the laser beam position and attenuator settings to obtain the best measurement of particle size.

Light scattering particle sizers illuminate a sample with a laser and analyze the intensity fluctuations of the light scattered from the particles at an angle of 173 degrees. To calculate particle size, the instrument can use the method of Photon Correlation Spectroscopy (PCS). PCS uses the fluctuating light intensity to measure the Brownian motion of particles in a liquid. The particle size is then calculated as the diameter of a sphere moving at the measured velocity.

The intensity of light scattered by a particle is proportional to the sixth power of the particle diameter. The Z-average size or cumulant mean is an average calculated from the intensity distribution; this calculation is based on the assumption that the particles are unimodal, monodisperse, and spherical. Related functions calculated from fluctuating light intensity are the intensity distribution and its mean. The mean of the intensity distribution is calculated based on the assumption that the particles are spherical. Both the Z-average size and the intensity distribution mean are more sensitive to larger particles than to smaller particles.

The volume distribution indicates the percentage of the total volume of particles that corresponds to particles within a given size range. The volume average size is the size of particles that corresponds to the mean of the volume distribution. This distribution is less sensitive to larger particles than the Z-average size because the volume of a particle is proportional to the cube of its diameter. Therefore, the volume average is typically smaller than the Z-average size. Within this document, the Z-average size will be referred to as the "average particle size."

pH Value If desired, the pH value can be determined as follows: 1.0 g of the material to be tested is dispersed in 10 ml of deionized water and stirred for about 5 minutes. A calibrated pH electrode is immersed in the suspension and the pH value is measured while stirring.

Elemental Composition If desired, elemental composition can be determined by X-ray fluorescence spectroscopy (XRF), for example, using a ZSX Primus II manufactured by Rigaku Holdings Corporation.

Flexural strength (FS)
If desired, the flexural strength can be determined by a three-point flexural strength test according to ISO 4049:2019 using test specimens of size 2 mm x 2 mm x 25 mm. The flexural strength is given in MPa.

Flexural modulus (FM)
If desired, the flexural modulus can be determined in conjunction with a flexural strength test, using a universal testing machine (e.g., Zwick) as the slope of the linear elastic portion of the stress-strain curve. Flexural modulus is given in GPa.

material

Synthesis of 11-(3-trimethoxysilylpropylcarbamoyloxy)undecyl 2-methylprop-2-enoate (C11 methoxy)

11-Hydroxyundecyl 2-methylprop-2-enoate (35.0 g, 137 mmol) was placed in a 250 mL three-necked RBF equipped with an internal thermometer and a magnetic stirrer, 3-isocyanatopropyl-trimethoxysilane (29.0 g, 141 mmol) was added, and the mixture was stirred for 48 h at 60° C. Infrared analysis showed complete consumption of the isocyanate.

Synthesis of 9-(3-trimethoxysilylpropylcarbamoyloxy)nonyl 2-methylprop-2-enoate (C9 methoxy)

9-Hydroxynonyl 2-methylprop-2-enoate (35.0 g, 153 mmol) was placed in a three-neck 250 mL RBF equipped with an internal thermometer and a magnetic stirrer, 3-isocyanatopropyl-trimethoxysilane (32.5 g, 158 mmol) was added, and the mixture was stirred at 60° C. for 48 h. Infrared analysis showed complete consumption of the isocyanate.

Synthesis of 6-(3-trimethoxysilylpropylcarbamoyloxy)hexyl 2-methylprop-2-enoate (C6 methoxy)

6-Hydroxyhexyl 2-methylprop-2-enoate (35.0 g, 188 mmol) was placed in a three-neck 250 mL RBF equipped with an internal thermometer and a magnetic stirrer, 3-isocyanatopropyl-trimethoxysilane (40.0 g, 195 mmol) was added, and the mixture was stirred for 48 h at 60° C. Infrared analysis showed complete consumption of the isocyanate.

Synthesis of 11-(3-triethoxysilylpropylcarbamoyloxy)undecyl 2-methylprop-2-enoate (C11 ethoxy)

11-Hydroxyundecyl 2-methylprop-2-enoate (24.0 g, 93.6 mmol) was placed in a flask, 3-isocyanatopropyltriethoxysilane (23.1 g, 93.4 mmol) was added, and the mixture was stirred for 48 hours at 60° C. Infrared analysis showed complete consumption of the isocyanate.

Synthesis of 2-(3-trimethoxysilylpropylcarbamoyloxy)ethyl 2-methylprop-2-enoate (C2 methoxy)

3-Isocyanatopropyltrimethoxysilane (34.46 g, 0.1678 mol) and K-Kat XK-672 (0.055 g, 1000 ppm based on total solids) were placed in a flask and cooled. HEMA (20.54 g, 0.1578 mol) was then added dropwise. The reaction was monitored by FTIR for the presence of the -NCO peak at 2265 ^cm .

M-C2-U-C11-TMS
M-C2-U-C11-TMS was prepared according to US Pat. No. 1,097,5229 (B1) (column 50, Comparative Synthesis Example 1).

Filler surface treatment Glass filler (G)
Filler GM32087 (UF 0.4), ethanol (ratio 1:2), and 1 wt. % (based on filler weight) of 25% aqueous ammonia were added to the slurry and mixed in an ultrasonic bath for 3 hours, followed by the addition of silane.

The mixture was stirred at room temperature for 3 hours, then the solvent was removed in a rotary evaporator (approximately 20 mbar) at 45°C, sieved through a 200 micron sieve, and further evaporated in a rotary evaporator (approximately 20 mbar) at 100°C for 1 hour.

Silica-zirconia cluster filler (SiO2/ZrO2)
Each silane (10.5% based on the filler weight) was dissolved in either ethyl acetate (EtOAc) or 1-methoxy-2-propanol (PGME). The solvent was used in proportions of 100% to 200% based on the filler weight. A magnetic stir bar was used to mix the silane into the solvent.

The filler SiO2/ZrO2 clusters were slowly added to the solution, ensuring that a magnetic stir bar continued to stir the solution as the viscosity of the solution increased with the addition of the filler. After the filler was added, 2 wt% (relative to the weight of the filler) of 30% aqueous ammonia was added to the slurry. If EtOAc was used, the slurry was allowed to react overnight at room temperature. The slurry was poured into a glass casserole dish and dried by evaporating the ethyl acetate in a solvent oven set at 85°C for 90 minutes. The filler was then sieved through a 70-micron sieve. If PGME was used, after the addition of ammonia, the slurry was placed on a rotary evaporator and heated to 85°C for 1 hour. It was then allowed to dry in a glass tray like the others.

Glass filler resin (Re-G)
The following resins were used: BisEMA2 (68.8 wt%), UDMA (19.7 wt%), TEGDMA (9.8 wt%), CPQ (0.16 wt%), DPIFP6 (0.3 wt%), EDMAB (0.6 wt%), BHT (0.09 wt%), TR796 (0.6 wt%).

The resin composition was prepared by mixing the ingredients and heating slightly under light-saving conditions until a clear solution was formed.

Silica-zirconia cluster filler resin (Re—SiO ₂ /ZrO ₂ )
The following resins were used: BisEMA2 (78.6%), TEGDMA (19.65%), CPQ (0.16%), DPIFP6 (0.3%), EDMAB (0.6%), BHT (0.09%), TR796 (0.6%).

The resin composition was prepared by mixing the ingredients and heating slightly under light-saving conditions until a clear solution was formed.

Curable Composition The surface-treated filler was mixed/kneaded with the resin composition until a homogeneous composition was obtained. A Flak-Tek speed mixer was used for mixing. The composition was degassed by applying a vacuum, if necessary.

The content of glass filler G in composition Re-G was 65% by weight. The content of cluster filler SiO2/ZrO2 in composition Re-SiO2/ZrO2 was 66% by weight.

The resulting compositions were filled into syringes and centrifuged. The compositions were further analyzed for viscosity (at various shear rates), flexural strength, and flexural modulus (Tables 2 and 3).

Tables 2 and 3 show the viscosity profiles of different compositions using various silane-surface-treated fillers.

As can be seen, the use of surface-treated fillers according to the present invention results in desirable low viscosities of curable compositions containing such fillers at low shear rates. Nearly Newtonian fluid behavior was observed.

On the other hand, as shown in the comparative examples, the use of surface-treated fillers with short alkylene bridges results in undesirably high viscosities at low shear rates.

Claims (15)

1. A dental composition comprising a hardenable component and a surface-treated filler,
The surface-treated filler comprises filler particles whose surfaces have been treated with a surface treatment agent, the surface treatment agent having the following properties:
comprising at least one (meth)acrylate moiety;
containing at least one hydrolyzable silane moiety;
containing only one urethane moiety;
a linear alkylene moiety AM1 connecting said at least one (meth)acrylate moiety to said urethane moiety;
the at least one hydrolyzable silane moiety comprises a linear alkylene moiety AM2 linking the urethane moiety; and the linear alkylene moiety AM1 comprises more carbon atoms than the linear alkylene moiety AM2.
Dental compositions. The surface treatment agent has the following properties:
containing only one (meth)acrylate moiety;
-Si(R ² ) _o (R ³ ) _3-o
wherein R ² = independently selected from Cl, Br, O—C _1-4 alkyl, O—C _1-4 acyl; R ³ = independently selected from C _1-4 alkyl; and o = 1:3.
comprising at least one hydrolyzable silane moiety preferably selected from
containing only one urethane moiety;
the (meth)acrylate moiety comprises one linear alkylene moiety AM1 bonding to the one urethane moiety, the linear alkylene moiety AM1 comprising 6 to 12 C atoms; and the at least one hydrolyzable silane moiety comprises one linear alkylene moiety AM2 bonding to the urethane moiety, the linear alkylene moiety AM2 comprising 1 to 4 C atoms.
The dental composition of claim 1 . The surface treatment agent is represented by the following formula:
H ₂ C=CHR ¹ -CO-O-(CH ₂ ) _n -X-CO-Y-(CH ₂ ) _m -Si(R ² ) _o (R ³ ) _3-o
wherein R ¹ =H or CH ₃ , R ² =Cl, Br, O—C _1-4 alkyl, O—C _1-4 acyl, R ³ =C _1-4 alkyl, X=O, Y=NH, n=6-12, m=1-4, o=1-3.
characterized by,
The dental composition according to claim 1 or 2. The dental composition according to any one of claims 1 to 3, wherein the surface treatment agent has a molecular weight Mw in the range of 300 g/mol to 800 g/mol. The dental composition according to any one of claims 1 to 4, wherein the surface treatment agent is selected from the following molecules and mixtures thereof:
the filler is selected from the group consisting of non-aggregated and non-agglomerated nano-sized particles of _SiO2 , _ZrO2 and mixtures thereof, aggregated nano-sized particles of _SiO2 , _ZrO2 and mixtures thereof, agglomerated nano-sized particles of _SiO2 , _ZrO2 , _Al2O3 and mixtures thereof _, non-acid-reactive particles of glass, silica, metal oxides or mixtures thereof;
acid-reactive particles of glass, metal oxides and hydroxides, and mixtures thereof;
The individual particles of the nano-sized particles have an average particle diameter of less than 100 nm.
The dental composition according to any one of claims 1 to 5. The dental composition according to any one of claims 1 to 6, comprising a surface-treated filler in an amount of 40% to 80% by weight, based on the weight of the dental composition. Ingredients:
a. a surface-treated filler in an amount of 40% to 80% by weight;
b. a curable component, particularly in an amount of 5% to 50% by weight;
c. an initiator system suitable for curing said curable component, particularly in an amount of 0.1% to 5% by weight;
d. additives, especially in an amount of 0% to 10% by weight,
The weight percentages are based on the weight of the dental composition.
The dental composition according to any one of claims 1 to 7. a surface-treated filler in an amount of 40% to 80% by weight, selected from non-aggregated, non-agglomerated nano-sized particles of _SiO2 , _ZrO2 or mixtures thereof, aggregated nano-sized particles of _SiO2 , _ZrO2 or mixtures thereof, agglomerated nano-sized particles of _SiO2 , _ZrO2 , _Al2O3 or mixtures thereof _, non-acid-reactive particles of glass, silica, metal oxides or mixtures thereof, acid-reactive particles of glass, metal oxides and hydroxides or mixtures thereof, wherein the individual particles of the nano-sized particles have an average particle diameter of less than 100 nm;
a hardenable component in an amount of 5% to 50% by weight, the hardenable component being selected from a polymerizable component that includes an acidic moiety, a polymerizable component that does not include an acidic moiety, and mixtures thereof;
an initiator system suitable for curing the curable component in an amount of 0.1 wt. % to 5 wt. %, the initiator system comprising a photoinitiator system and/or a redox initiator system;
an additive in an amount of 0% to 10% by weight;
The weight percentages are based on the weight of the dental composition;
The surface treatment agent has the following properties:
containing only one (meth)acrylate moiety;
containing at least one tri-methoxysilane or tri-ethoxysilane moiety;
containing only one urethane moiety;
comprising one linear alkylene moiety AM1 linking said (meth)acrylate moiety to said urethane moiety, said linear alkylene moiety AM1 comprising 6 to 12 C atoms,
the at least one tri-methoxysilane or tri-ethoxysilane moiety comprises one linear alkylene moiety AM2 linking the urethane moiety, the linear alkylene moiety AM2 comprising 1 to 4 C atoms,
The dental composition according to any one of claims 1 to 8. The following properties, without rheology modifiers and before solidification:
a. Viscosity: 5 Pa ^* s to 1,500 Pa ^* s at 25°C and a shear rate of 0.01 s ^-1 ;
b. Capable of being solidified within 10 minutes after irradiation with light having a wavelength in the range of 400 nm to 700 nm;
c. pH value: 7 or less, either alone or in combination;
The dental composition according to any one of claims 1 to 9. After solidification, the following properties:
a. Flexural strength: determined to be 100 MPa to 200 MPa according to ISO 4049 (2019);
b. Flexural modulus: determined according to ISO 4049 (2019) to be between 4 GPa and 8 GPa, either alone or in combination;
The dental composition according to any one of claims 1 to 10. A dental composition according to any one of claims 1 to 11, and the following parts, alone or in combination: a dental adhesive, a dental curing light, and an application tool.
Kit of parts. 12. A dental composition for use in a method of restoring a tooth in the mouth of a mammal according to any one of claims 1 to 11, said method comprising the steps of contacting said dental composition with the surface of the tooth to be restored;
and curing the dental composition by applying radiation.
The dental composition according to any one of claims 1 to 11. A method for producing the dental composition according to any one of claims 1 to 11, comprising:
combining the filler particles with the surface treatment, optionally using a dispersing liquid;
reacting the surface treatment agent with the filler particles;
removing the optional dispersing liquid;
and optionally drying and sieving the surface-treated filler particles. Use of the surface-treated filler according to any one of claims 1 to 11 to reduce the viscosity of the dental composition according to any one of claims 1 to 11 at low shear rates.