Curable composition for dental purposes

Abstract

The invention relates to a curable composition for dental purposes. The invention is characterized in that the composition comprises core-shell impact modifiers and 0.1 to 10 wt.% of a binder based on long-chain mono-functional (meth)acrylic acid esters, wherein the ester group has a carbon chain with at least 3 carbon atoms. The invention also relates to the use of the composition as a dental material or a dental auxiliary material, to a dental product made of the composition, and to a method for producing the dental product.

Description

[0001] Curable composition for dental purposes

[0002] The present invention relates to a curable composition for dental purposes, which is characterized in that it comprises core-shell impact modifiers and 0.1 to 10 wt.% of a binder based on longer-chain monofunctional (meth)acrylic acid esters, wherein the ester group has a carbon chain with at least 3 carbon atoms, the use of the composition as a dental material or dental auxiliary, a dental product produced from the composition and a process for producing the dental product.

[0003] Curable compositions such as those used in additive manufacturing are known to those skilled in the art and have also found their way into the dental field, so that dental products such as dental restorations can now be manufactured with high precision and individually adapted.

[0004] EP 3 564 282 describes curable compositions for use in a high-temperature lithography-based photopolymerization process comprising a specific oligomeric dimethyl acrylate as a glass transition modifier.

[0005] US 2021 / 0017302 discloses a resin composition comprising: one or more photoinitiators; one or more hard crosslinkers, wherein the one or more hard crosslinkers have at least two reactive groups and are present at 20-75 wt% (based on the total weight of the composition); and one or more soft crosslinkers and / or one or more reactive diluents, wherein the one or more soft crosslinkers have at least two reactive groups and are present at 2-70 wt% (based on the total weight of the composition) and / or the one or more reactive diluents have only one reactive group and are present at 2-70 wt% (based on the total weight of the composition).

[0006] WO 2014 / 078537 relates to a composition for the production of three-dimensional dental products, which comprises a mixture of at least 1% methyl methacrylate and / or ethyl methacrylate, 5 to 10% impact modifiers made of silicone-acrylic-based rubber, wherein the core is silicone and the shell is PMMA-acrylic, which does not dissolve but swells and forms a colloid at room temperature or elevated temperature, 1 to 90% of at least one mono- or multifunctional (meth)acrylate, 0 to 60% of at least one inorganic filler, 0 to 60% of at least one organic filler, 0 to 10% pigments and 0.01 to 10% photoinitiators.

[0007] WO 2020 / 182810 relates to a polymerizable, radiation-curable composition comprising (i) monomers and (ii) at least one component, wherein the monomers comprise at least (a) a first monomer having a glass transition point (TG) of the homopolymer of this first monomer of greater than or equal to 120 °C and at least (b) a second monomer having a TG of the homopolymer of the second monomer of less than or equal to 100 °C, wherein at least one of the at least one first monomer or the at least one second monomer has an alicyclic group and the at least one further component comprises at least one photoinitiator for the UV and / or Vis range or a photoinitiator system for the UV and / or Vis range.

[0008] EP 3 925 994 describes a photocurable composition comprising a di(meth)acrylate monomer (A) having two (meth)acryloyloxy groups and two urethane bonds, an acrylic monomer (B) having one acryloyl group and a photopolymerization initiator.

[0009] WO 2019 / 204807 discloses a thermosetting composition suitable for use in additive manufacturing processes and containing high concentrations of urethane methacrylate oligomers having at least one polymerizable group and a number-average molecular weight of 750 to 4000 g / mol, an effective amount of a monofunctional reactive diluent monomer, a defined concentration of a network former having a molecular weight lower than that of the urethane methacrylate oligomer, optionally a photoinitiator and optionally additives.

[0010] EP 3 494 954 relates to a photocurable composition used for producing a dental prosthesis or the like by stereolithography, comprising: a photopolymerization initiator; and a

[0011] (Meth)acrylic monomer component comprising an acrylic monomer (X) having no aromatic rings and having a ring structure other than an aromatic ring and two or more acryloyloxy groups in one molecule and having an M w from 200 to 800 and at least one (meth)acrylic monomer (A) having one or more ether bonds and two (meth)acryloyloxy groups in one molecule and having an M w from 200 to 400, a (meth)acrylic monomer (B) having a ring structure other than an aromatic ring and a (meth)acryloyloxy group in one molecule and having an M w from 130 to 240, a (meth)acrylic monomer (C) having a hydrocarbon skeleton and two (meth)acryloyloxy groups in one molecule and having an Mw from 190 to 280, and a (meth)acrylic monomer (D) having one or more aromatic rings and a (meth)acryloyloxy group in one molecule and having an M w from 140 to 350.

[0012] US 2018 / 0000570 describes a method for forming a dental component using a polymerizable composition containing core-shell impact modifiers, methyl methacrylate and an initiator.

[0013] US 2009 / 0192240 discloses curable dental composite materials comprising i) non-agglomerated nanofillers having particle sizes of about 1 to about 50 nm; and ii) core-shell polymer particles having an elastic core compound and a substantially non-elastic shell compound.

[0014] Compositions conventionally used in additive manufacturing have the disadvantage of exhibiting fracture behavior due to their low impact strength, making them unsuitable for dental applications. The impact strength required for dental applications is achieved by adding impact modifiers or using phase-separated plastics. To achieve sufficient incorporation of the impact modifiers into the polymer matrix, components with a low vapor pressure are generally used. These are highly volatile and result in an unpleasant odor in the dental product. Furthermore, the addition of impact modifiers impairs the mechanical properties of the composition, particularly affecting fracture toughness and crack energy, but also flexural strength. Therefore, there is still a need for improved compositions for the production of dental products.

[0015] It was surprisingly found that the emission of pollutants into the environment through the processing of such materials into dental products, which is usually characterized by an unpleasant odor, can be reduced by using compounds with a higher vapor pressure, without this leading to an impairment of the printability of such compositions, for example in the context of additive manufacturing processes.

[0016] Therefore, a first object of the present invention is a curable composition for dental purposes, comprising, in each case based on the total weight of the composition:

[0017] • a) 0.1 to 10% by weight of a binder based on a monomeric, monofunctional (meth)acrylic acid ester, wherein the ester group has a carbon chain of 3 or more carbon atoms;

[0018] • b) 1 to 15 wt.% of one or more core-shell impact modifiers; and

[0019] • c) 1 to 90 wt.% of a matrix material; and

[0020] • d) 0.01 to 3 wt.% of at least one initiator.

[0021] It was surprisingly found that the composition according to the invention not only generally reduces the unpleasant odor of dental restorations, but also makes the composition more temperature-stable in the liquid state, thus achieving better processability. In particular, the use of a longer-chain, monofunctional (meth)acrylic acid ester as a binder results in the composition possessing mechanical properties that allow its use in the dental field. It was surprisingly found that the addition of the binder according to the invention improved the fracture toughness and crack work of the dental composition while maintaining the same flexural strength.

[0022] The ester group of the binder comprises a carbon chain of 3 or more carbon atoms, which may have further substituents. In a preferred embodiment, the carbon chain comprises 4 or more carbon atoms, preferably 5 or more carbon atoms. However, the carbon chain preferably has no more than 16 carbon atoms in order not to impair the processability of the composition. In a particularly preferred embodiment, the binder is an aliphatic monofunctional (meth)acrylic acid ester with an ester group having a carbon chain C3H7 to C16H33, preferably C3H7 to C6H13. In a particularly preferred embodiment, the binder is selected from the group consisting of propyl (meth)acrylate, butyl (meth)acrylate, pentyl (meth)acrylate, and hexyl (meth)acrylate, and their isomers. Mixtures of the compounds mentioned can also be used.

[0023] In a preferred embodiment, the content of binder in the composition according to the invention is 0.2 to 7 wt.%, preferably 0.5 to 5 wt.%, based on the total weight of the composition.

[0024] To avoid the unpleasant odors associated with short-chain (meth)acrylates, especially methyl (meth)acrylate and ethyl (meth)acrylate, the composition according to the invention is preferably free of these compounds. In a preferred embodiment, the content of monomeric methyl (meth)acrylate and / or ethyl (meth)acrylate in the composition according to the invention is preferably no more than 0.5 wt.%, particularly preferably less than 0.5 wt.%, in particular less than 0.1 wt.%, in each case based on the total weight of the composition.

[0025] The impact modifiers contained in the composition according to the invention are preferably selected from the group of silicone-(meth)acrylic-based and / or (meth)acrylic-(meth)acrylic-based core-shell particles. The impact modifiers are particularly preferably core-shell particles with a silicone core and a PMMA shell, or core-shell particles with a (meth)acrylic-based core and a PMMA shell. Within the scope of the present invention, it has been found that such impact modifiers, particularly in compositions used in additive manufacturing, contribute to obtaining products with high mechanical strength and excellent physical properties.

[0026] The composition according to the invention further contains at least one matrix material. The matrix material is preferably a mono- or multifunctional (meth)acrylate or mixtures of these compounds. Particularly preferably, the matrix material is different from the binder.

[0027] Compounds known to those skilled in the dental industry can be used as matrix materials. Preferably, the matrix material is a polymerizable (meth)acrylic compound such as cyclohexyl (meth)acrylate, 4-tert-butylcyclohexyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, 2-phenoxyethyl (meth)acrylate, allyl acrylate, isobornyl (meth)acrylate, stearyl (meth)acrylate, phenoxybenzyl (meth)acrylate, o-phenylphenolethyl (meth)acrylate, 1,14-tetradecane dimethacrylate,

[0028] Dimethyloltricyclodecandiacrylat, Glycerindiacrylat, Glycerintriacrylat, Ethylenglycoldiacrylat, Diethylenglycoldiacrylat, Triethylenglycoldimethacrylat, Tetraethylenglycoldi(meth)acrylat, 1,3-Propandioldiacrylat, 1,3-

[0029] Propandioldimethacrylat, Trimethylolpropantri(meth)acrylat, 1,2,4-

[0030] Butantriotrimethacrylat, 1,4-Cyclohexandioldiacrylat, 1,4-

[0031] Cyclohexandioldimethacrylat, 1,6-Hexandioldi(meth)acrylat,

[0032] Pentaerythritol triacrylate, pentaerythritol tetraacrylate, pentaerythritol tetramethacrylate, sorbitol hexacrylate, 2,2-bis[4-{2-hydroxy-3-acryloyloxypropoxy)phenyl]propane, and 2,2-bis[4-(2-hydroxy-3-methacryloyloxypropoxy)phenyl]propane (Bis-GMA). In particular, the matrix material is selected from the group consisting of tricyclodecanedimethanol dimethacrylate, ethylene glycol phenyl ether methacrylate, isobornyl methacrylate, 3,3,5-trimethylcyclohexyl methacrylate, and tricyclodecanyl acrylate, as well as mixtures thereof.

[0033] In a preferred embodiment, the composition according to the invention comprises up to 70 wt. %, based on the total weight of the composition, of at least one difunctional urethane (meth)acrylate. In a further preferred embodiment, the content of difunctional urethane (meth)acrylate is at least 25 wt. %, particularly preferably 30 to 45 wt. %, in each case based on the total weight of the composition. Aliphatic polyesters / polyethers based on urethane di(meth)acrylate oligomers, in particular UDA and UDMA, are preferably used as the difunctional urethane (meth)acrylate. In this way, it was possible, in particular, to increase the elongation at break of products produced from the composition according to the invention.

[0034] The curable composition according to the invention further contains initiators that initiate the curing of the composition. These initiators can be thermal initiators or photoinitiators. The initiator is preferably present in an amount of 0.01 to 2 wt. %, in particular 0.5 to 1.5 wt. %, based on the total weight of the curable composition. In a preferred embodiment, the initiator is selected from the group consisting of benzophenones, benzoins, or o-diketones to render the composition photocurable. Preferred initiators are also camphorquinone (CQ) or cationic initiators such as 4-octyloxyphenylphenyliodonium hexafluoroantimonate (OPPI).Further suitable initiators are those selected from the class of acylphosphine oxides, such as monoacylphosphine oxides, bisacylphosphine oxides, and triacylphosphine oxide, in particular 2,4,6-trimethylbenzoyldiphenylphosphinate (TPO) and ethyl(2,4,6-trimethylbenzoyl)phenylphosphinate (TPO-L). Curing of the composition according to the invention is preferably initiated by irradiation with light, preferably with a wavelength of 365 to 500 nm, particularly preferably 385 to 405 nm, so that instruments commonly used in the dental field can be used. Within the scope of the present invention, it is also preferred to use mixtures of thermal initiators and photoinitiators. In this way, the composition according to the invention can be shaped, for example, in a 3D printer, with light-based systems such as DLP, LCD, or stereolithographs being preferred.The final curing can then be achieved by further irradiation or thermal treatment.

[0035] The curable composition according to the present invention may comprise further components to adapt its properties to the intended application. Therefore, an embodiment is preferred in which the curable composition further comprises inorganic fillers. These fillers may be present in the composition according to the invention in an amount of up to 60 wt.%, based on the total weight of the composition. Preferably, the inorganic fillers are selected from the group consisting of silicon oxide, zirconium oxide, aluminum oxide, alumina, apatite, titanium dioxide, and glass microbeads. These inorganic fillers have proven particularly advantageous when the curable composition is used for the production of artificial teeth.

[0036] In a further preferred embodiment, the curable composition of the present invention further contains organic fillers, which may be present in an amount of up to 60 wt.%, based on the total weight of the composition. These organic fillers are preferably those selected from the group consisting of acrylate beads, especially PMMA beads, and rubber beads. These fillers can be used, in particular, to improve the shrinkage of the composition during curing and its mechanical properties.

[0037] Particularly in cases where the composition according to the invention is used for the production of artificial teeth, the composition may further comprise coloring substances. The amount of coloring substance in the composition depends on the desired color result, but in a preferred embodiment is not more than 10 wt. %, particularly preferably less than 2.5 wt. %, in particular 0.1 to 2 wt. %, based on the total weight of the composition. Both organic and inorganic substances can be used as coloring substances, with inorganic color pigments being particularly preferred, since these allow the best results to be achieved with regard to the optical properties of dental restorations.

[0038] The curable composition according to the present invention preferably has a flexural modulus of less than 5 GPa in the cured state, preferably less than 5 GPa, in particular 2 to 4 GPa, determined according to DIN EN ISO 20795-1 (2013) on printed specimens.

[0039] The curable composition is preferably a one-component composition. Therefore, the complex mixing required for two-component compositions can be dispensed with.

[0040] The curable composition is intended for use in particular for dental purposes. Therefore, an embodiment in which the composition is printable and can be processed using additive manufacturing methods is preferred. In this way, for example, dental restorations such as artificial teeth can be provided with a high degree of color and fit accuracy. Furthermore, an embodiment in which the curable composition can be milled in cured form, for example, to enable manual adjustments.

[0041] The curable composition of the present invention is particularly tailored for use in dental applications. Therefore, a further subject of the present invention is the use of a curable composition according to the present invention as a dental material. Thus, the composition according to the invention is used in particular for the production of dental restorations, such as artificial teeth and full and partial dentures, and other dental products such as tooth alignment corrections, or as an auxiliary material for dental applications, for example, for the production of models and templates.

[0042] The present invention further relates to a dental product made from a curable composition according to the present invention. Such a dental product is particularly suitable for dental restorations such as artificial teeth, full and partial dentures, and tooth alignment correction measures such as braces or splints. In a further preferred embodiment, the composition according to the invention is used as an auxiliary agent for dental applications, such as for the production of models or templates.

[0043] The present invention further provides a method for producing a dental product by introducing a curable composition of the present invention into an additive manufacturing device and curing it. Preferably, the curable composition is applied layer by layer, and the individual layers are bonded together, for example, by irradiation with light. The composition can be applied, for example, based on previously determined patient data in order to achieve a high degree of precision. The final curing of the product is preferably achieved by further irradiation or thermal treatment.

[0044] The present invention is further illustrated by the following examples, which, however, are not to be understood as limiting the scope of the invention.

[0045] Examples:

[0046] The following materials were used to prepare the compositions, with the values ​​in the table being given as % by weight.

[0047] • UDA / UDMA: Urethane diacrylate / urethane dimethacrylate

[0048] • MA: Matrix material, mixture of mono- and multifunctional (meth)acrylates, available from Arkema, France, Sartomer product family

[0049] • MMA: Methyl methacrylate

[0050] • EMA: Ethyl methacrylate

[0051] • Binder 1: Butyl-2-methyl-2-propenoate • Binder 2: Butyl-2-methylprop-2-enoate

[0052] • Binder 3: Isopropyl methacrylate

[0053] • Impact modifier 1 : Core-Shell (silicone / PMMA)

[0054] • Impact modifier 2: Core-Shell ((Meth)Acrylate / PMMA)

[0055] • Initiator: TPO-L

[0056] *) Comparative compositions

[0057] The mechanical properties were determined as follows:

[0058] Flexural strength and flexural modulus: according to DIN EN ISO 20795-1 (2013) on printed specimens

[0059] Crack energy and fracture toughness (kmax): based on DIN EN ISO 20795-1 (2013), whereby the specimens were printed including the pre-crack and pre-notch, and the measurement was carried out outside of the water bath. As can be seen from the data in the table, the comparative compositions D and G, which do not contain a binder, exhibit inferior mechanical properties, which can be improved by the addition of compounds acting as binders (cf. compositions AC, E, and F). As can also be seen from the table, replacing the critical binders MMA and EMA with longer-chain acrylic acid esters in compositions B and C does not have a negative effect on the mechanical properties. In fact, the use of the binder improved the crack energy and fracture toughness (kmax), while maintaining the same flexural strength and flexural modulus.

Claims

Patent claims 1. Hardenable composition for dental purposes, comprising the composition, each based on the total weight of the composition: • a) 0.1 to 10 wt% of a binder based on a monomeric monofunctional (meth)acrylic acid ester, wherein the ester group has a carbon chain of 3 or more carbon atoms; • b) 1 to 15 wt.% of one or more core-shell impact modifiers; and • c) 1 to 90 wt.% of a matrix material; and • d) 0.01 to 3 wt.% of at least one initiator 2. Curable composition according to claim 1, characterized in that the ester group of the binder has a maximum of 16 carbon atoms.

3. Curable composition according to at least one of the preceding claims, characterized in that the content of monomeric methyl(meth)acrylate and / or monomeric ethyl(meth)acrylate is less than 0.5 wt.%, based on the total weight of the composition.

4. Curable composition according to at least one of the preceding claims, characterized in that the impact modifier(s) is / are selected from the group of core-shell particles based on silicone (meth)acrylic and (meth)acrylic (meth)acrylic.

5. Curable composition according to at least one of the preceding claims, characterized in that the composition comprises up to 70 wt.%, based on the total weight of the composition, of at least one difunctional urethane(meth)acrylate.

6. Curable composition according to at least one of the preceding claims, characterized in that the initiator is selected from the group consisting of thermal initiators and light initiators.

7. A curable composition according to at least one of the preceding claims, characterized in that the composition further contains up to 60 wt.%, based on the total weight of the composition, of an inorganic filler, preferably selected from the group consisting of silicon oxide, ziconic oxide, aluminum oxide, alumina, apatite, titanium dioxide and micro glass beads.

8. Curable composition according to at least one of the preceding claims, characterized in that the composition further contains up to 60 wt.%, based on the total weight of the composition, of an organic filler, preferably selected from the group consisting of (meth)acrylate beads, in particular PMMA beads, and rubber beads.

9. A hardenable composition according to at least one of the preceding claims, characterized in that the composition further contains up to 10 wt.%, based on the total weight of the composition, coloring substances.

10. Curable composition according to at least one of the preceding claims, characterized in that the composition is printable.

11. Use of a composition according to at least one of the preceding claims as a dental material and / or as an auxiliary material for dental applications.

12. Dental product made from a curable composition according to at least one of claims 1 to 10.

13. Method for manufacturing a dental product by introducing and curing a curable composition according to at least one of claims 1 to 10 into an additive manufacturing device.

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