Aesthetic dental filling material with high cure depth

Abstract

A dental material comprising at least one radically polymerizable monomer, at least one radiopaque filler, at least one composite filler, at least one inorganic filler, and at least one initiator for radical polymerization. The dental material is particularly suitable as a dental filling material. The object of the present invention is to provide a dental material that does not have the above-mentioned drawbacks and has high radiopacity, so that it can be sufficiently distinguished from natural tooth substance. Furthermore, the material allows for simplified production of aesthetically appealing restorations and is particularly suitable as a dental filling material.

Description

[Technical Field]

[0001] The present invention relates to a radiopaque dental material that is characterized by a large depth of cure and allows for the easy production of aesthetically appealing dental restorations, said material being particularly suitable as a dental filling material. [Background technology]

[0002] The dental market offers an almost limitless number of filling materials for all possible indications in filling procedures. Development in the field of methacrylate-based filling materials has now reached such a high level that professionally restored teeth can no longer be distinguished from their natural counterparts. This makes it difficult to distinguish between restorations and natural tooth materials, which is particularly disadvantageous in subsequent processing. Therefore, there is a need for dental materials that have high radiopacity in addition to high aesthetics, and therefore can be clearly distinguished from natural tooth materials.

[0003] The creation of aesthetically pleasing restorations involves considerable effort on the part of the dentist. Currently, two to four different substances are commonly used in aesthetic fillings to mimic as naturally as possible the natural appearance of the missing hard dental tissue. To replicate the color of various natural teeth, a color palette with 30 or more different shades in various opacities is provided, from which the optimal material combination must be selected for each treatment case. It would be desirable to have materials available that would allow the creation of aesthetically pleasing restorations with even lower material costs.

[0004] Dental filling materials based on methacrylates are often called plastic fillers or more precisely composites. Composite materials contain polymerizable organic base materials and fillers, as well as various additives, such as stabilizers, initiators, and pigments. The filler content depends to a large extent on the desired intended use and can be up to 90% by weight.

[0005] The polymerizable organic matrix of dental filling composites and adhesives is largely based on a mixture of dimethacrylates, usually containing high-viscosity bis-GMA as a crosslinker. Bis-GMA provides good mechanical properties with relatively little shrinkage. However, commercially available bis-GMA often contains bisphenol A as an impurity. Further examples of frequently used dimethacrylates are urethane dimethacrylate and the low-viscosity dimethacrylates commonly used as diluent monomers: bis(methacryloyloxymethyl)-tricyclo[5.2.1.]decane (TCDMA), decanediol-1,10-dimethacrylate (D3MA), and triethylene glycol dimethacrylate (TEGDMA).

[0006] Typically, these materials contain initiators for radical polymerization, and today, light-curing materials containing photoinitiators are dominant in filling procedures. The disadvantage of light-curing materials is that the light required for curing can only penetrate the material to a limited depth, making it time-consuming to place particularly large fillers. Therefore, in the so-called incremental technique, the filler is built up in layers from a composite material, each layer being approximately 2 mm thick and having to be cured individually.

[0007] So-called bulk filling materials, which allow a cure depth of approximately 4 mm per layer, overcome this drawback. However, these materials often lack the desired aesthetic properties and are therefore unsuitable for restoring anterior teeth, or are only suitable to a limited extent for this purpose. The depth of cure is related to the material's translucency; high translucency and good cure depth are achieved when the organic matrix and filler used have corresponding refractive indices. The drawback here is that, due to their high translucency, such composites insufficiently cover the underlying dentin, which is problematic for aesthetic reasons because the color of the dentin differs from the color of the visible dental enamel.

[0008] WO 2016 / 026915 A1 discloses a radically polymerizable dental material that combines a high depth of cure with good aesthetic properties. The material is prepared by using a monomer mixture with a refractive index n of 1.50 to 1.70. D The dental material is characterized by having a refractive index of 0.050 to 2.0 μm, where the refractive index of the monomer mixture before curing matches or is at most 0.013 greater than the refractive index of the filler, but after curing is at least 0.02 greater than the refractive index of the filler. Before polymerization, the dental material has high translucency and therefore a large depth of cure. Translucency decreases during polymerization. The material can contain radiopaque fillers, such as radiopaque glasses or ytterbium fluoride, with particle sizes of 0.050 to 2.0 μm. The material is suitable as a bulk filling material, but is not packable due to its free flow.

[0009] U.S. Patent No. 4,629,746 discloses a micro-filled dental material containing a rare earth metal fluoride, such as ytterbium trifluoride, as a radiopaque filler, having a primary particle size of 5 to 700 nm, preferably 50 to 300 nm. In addition to the radiopaque filler, the material can contain a non-radiopaque filler, such as precipitated or pyrogenic silica. The material has high radiopacity and good transmittance.

[0010] EP 1 234 567 A2 discloses prepolymers with a defined particle size distribution, which contain a small proportion of finely divided particles less than 10 μm in size. These fillers result in polymerizable compositions with low polymerization shrinkage and good polishability, surface smoothness, and abrasion resistance. To increase radiotransparency, the prepolymers can contain radiopaque fillers such as ytterbium trifluoride with a particle size of 300 nm.

[0011] WO 2017 / 149242 A1 discloses the preparation of a colloidal suspension of ytterbium fluoride having a particle size of less than 100 nm and its use for the preparation of dental materials.

[0012] US Patent No. 9,833,388 (B2) discloses dental materials containing ytterbium fluoride particles with particle sizes between 25 and 120 nm, which are said to exhibit a reduced number of artifacts in digital volume tomography.

[0013] In addition to the absolute shrinkage of the composite, of increasing importance is its shrinkage force. In the radical polymerization of dental composites, the polymerization shrinkage (ΔV P ) leads to a volume reduction, which can lead to the very unfavorable formation of peripheral gaps in filled composites. In the polymerization of monofunctional methacrylates, the volume reduction can be compensated for by the flow of the polymers that are formed, so the shrinkage during polymerization does not lead to the buildup of polymerization shrinkage stress (PSS). However, in the cross-linking polymerization of multifunctional methacrylates, a three-dimensional polymer network is formed within a few seconds, preventing viscous flow and resulting in the buildup of considerable PSS. EP 2 965 741 A1 discloses radically polymerizable sulfur-containing monomers such as 2-(toluene-4-sulfonylmethyl)acrylic acid lauryl ester as chain regulators for reducing PSS in dental materials. [Prior art documents] [Patent documents]

[0014] [Patent Document 1] International Publication No. 2016 / 026915 [Patent Document 2] U.S. Patent No. 4,629,746 [Patent Document 3] European Patent Application Publication No. 1234567 [Patent Document 4] International Publication No. 2017 / 149242 [Patent Document 5] U.S. Patent No. 9,833,388 [Patent Document 6] European Patent Publication No. 2965741 Summary of the Invention [Means for solving the problem]

[0015] The object of the present invention is to provide a dental material that does not have the above-mentioned drawbacks and that has high radiopacity, so that it can be sufficiently distinguished from natural tooth material, and that further allows for the simplified production of aesthetically appealing restorations and is particularly suitable as a dental filling material.

[0016] The purpose of this is to (a) at least one radically polymerizable monomer; (b) at least one radiopaque filler; (c) at least one inorganic filler; (d) at least one composite filler; and (e) at least one initiator for radical polymerization This is achieved according to the invention by a dental material containing

[0017] The particles of composite filler (d) preferably have a spherical shape.

[0018] It has now been found that dental materials that meet the above requirements can be prepared through a targeted selection of substances known per se.

[0019] Radically polymerizable polyfunctional monomers, especially (meth)acrylamides and (meth)acrylates, are preferred as monomer (a). Polyfunctional, especially difunctional methacrylates, and polyfunctional, especially difunctional hybrid monomers are particularly preferred. Hybrid monomers are monomers containing both (meth)acrylamide and (meth)acrylate groups. By polyfunctional monomers is meant compounds having two or more, preferably two to four, especially two radically polymerizable groups. In an embodiment of the present invention, for example, the following items are provided: (Item 1) A dental material, comprising: (a) at least one radically polymerizable monomer; (b) at least one radiopaque filler; (c) at least one inorganic filler; (d) at least one composite filler, and (e) at least one initiator for radical polymerization, preferably a photoinitiator A dental material comprising: (Item 2) 2. The dental material according to item 1, comprising as component (d) a composite filler with spherical particles. (Item 3) 1,6-bis-[2-methacryloyloxyethoxycarbonylamino]-2,2,4-trimethylhexane (RM3), N-(2-methacryloyloxyethyl)carbamic acid-(2-methacryloyloxyethyl) ester (V837), tetramethylxylylenediurethane dimethacrylate (V380), bisphenol A dimethacrylate, 2,2-bis[4-(2-hydroxy-3-methacryloyloxypropyl)phenyl]propane (bis-GMA), ethoxylated or propoxylated bisphenol A dimethacrylate Methacrylate, bisphenol A dimethacrylate 2-[4-(2-methacryloyloxyethoxyethoxy)phenyl]-2-[4-(2-methacryloyloxyethoxy)phenyl]propane) (SR-348c, 3 ethoxy groups), 2,2-bis[4-(2-methacryloxypropoxy)phenyl]propane, 2-{[(2-(N-methylacrylamido)-ethoxy)-carbonyl]-amino}-ethyl methacrylate (V850), bis-(3-methacryloyloxymethyl)tricyclo-[5.2.1.0 2,6 ] decane (TCP), 1,10-decanediol dimethacrylate (D 3 3. The dental material according to item 1 or 2, comprising as radically polymerizable monomer (a) 2-([1,1'-biphenyl]-2-oxy)ethyl methacrylate, 2-([1,1'-biphenyl]-2-oxy)ethyl methacrylate, or a mixture thereof. (Item 4) In each case relative to the total weight of component (a), (a-1) from 20 to 80% by weight, preferably from 30 to 70% by weight, and very particularly preferably from 40 to 67% by weight, of at least one urethane dimethacrylate, (a-2) 10 to 40% by weight, preferably 12 to 30% by weight, and very particularly preferably 14 to 25% by weight, of at least one bisphenol A derivative, preferably ethoxylated or propoxylated bisphenol A dimethacrylate, very particularly preferably SR-348c, (a-3) optionally at least one tricyclic dimethacrylate, preferably tricyclodecane dimethanol dimethacrylate (TCP), in an amount of up to 40% by weight, preferably from 5 to 30% by weight, and very particularly preferably from 10 to 25% by weight, and (a-4) optionally up to 20% by weight, preferably 4 to 20% by weight, and particularly preferably 4 to 10% by weight, of other monomers, i.e., monomers not included in one of the groups (a-1) to (a-3) and (a-5), preferably D 3 MA, (a-5) optionally, up to 8% by weight, preferably 0.1 to 7% by weight, and particularly preferably 0.5 to 6% by weight, of at least one chain regulator; 4. Dental material according to any one of the preceding claims, comprising as radically polymerizable monomer (a) a mixture of (Item 5) General formula 1:

change

[0020] According to a preferred embodiment, the material according to the invention does not contain monofunctional monomers. By monofunctional monomers is meant compounds with one radically polymerizable group. Materials containing exclusively polyfunctional, in particular difunctional, methacrylates as component (a) are preferred.

[0021] A single monomer or preferably a mixture of monomers can be used as component (a). According to the present invention, monomers and mixtures of monomers that exhibit a large change in refractive index during polymerization are preferred. The monomer component (a) preferably has a refractive index of 1.495 to 1.520, particularly preferably 1.505 to 1.515. The refractive index of the monomer mixture is preferably set to match the refractive index of the filler (c) before curing or to be at most 0.03 higher than it. The refractive index of the monomer or monomer mixture is preferably 0.002 to 0.02 higher, particularly preferably 0.005 to 0.015 higher than the refractive index of the filler (c). The refractive index of component (a) can be set by mixing monomers with different refractive indices.

[0022] Before polymerization, the dental material according to the present invention has high translucency because the refractive indexes of the monomer and the filler are only slightly different from each other.Therefore, the light used for polymerization penetrates deep into the material, ensuring a large curing depth.During polymerization, the refractive index of the monomer increases, while the refractive index of one or more fillers remains unchanged.This increases the refractive index difference between the monomer and the filler, and the translucency decreases accordingly.This is advantageous for aesthetic reasons, because it can better cover the deeper, differently colored tooth layers.

[0023] The monomers used as component (a) are preferably selected so that the difference in refractive index between the unpolymerized and polymerized state is at least 0.015, preferably at least 0.02. According to a particularly preferred embodiment, the difference in refractive index is from 0.015 to 0.04, particularly preferably from 0.021 to 0.035, and very particularly preferably from 0.025 to 0.030.

[0024] Monomers that are particularly preferred according to the invention are: 1,6-bis-[2-methacryloyloxyethoxycarbonylamino]-2,2,4-trimethylhexane (RM3; addition product of 2-hydroxyethyl methacrylate and 2,2,4-trimethylhexamethylene diisocyanate), N-(2-methacryloyloxyethyl)carbamic acid-(2-methacryloyloxyethyl) ester (V837; CAS No.: 139096-43-8), tetramethylxylylenediurethane dimethacrylate (V380), bisphenol A dimethacrylate, 2,2-bis[4-(2-hydroxy-3-methacryloyloxypropyl)phenyl]propane (bis-GMA), ethoxylated or propoxylated bisphenol A dimethacrylates, for example bisphenol A dimethacrylate 2-[4-(2-methacryloyloxyethoxyethoxy)phenyl]-2 -[4-(2-methacryloyloxyethoxy)phenyl]-propane) (SR-348c; containing three ethoxy groups), 2,2-bis[4-(2-methacryloxypropoxy)phenyl]propane, 2-{[(2-(N-methylacrylamido)-ethoxy)-carbonyl]-amino}-ethyl methacrylate (V850, CAS number: 2004672-68-6), bis-(3-methacryloyloxymethyl)tricyclo-[5.2.1.0] 2,6 ]decane (TCP), 1,10-decanediol dimethacrylate (D3MA), 2-([1,1'-biphenyl]-2-oxy)ethyl methacrylate, and mixtures thereof.

[0025] The dental material according to the invention preferably contains a mixture of various monomers as monomer component (a). According to a particularly preferred embodiment, component (a) contains one or more monomers from the group of urethane di(meth)acrylates, in particular urethane dimethacrylates.

[0026] Monomers with aromatic groups are preferred as urethane dimethacrylates, in particular the urethane di(meth)acrylate derivatives of 1,3-bis(1-isocyanato)-1-methylethyl)benzene described in EP 0 934 926 A1, with tetramethylxylylene diurethane di(meth)acrylate (V380) being particularly preferred: [ka]

[0027] In the illustrated formula, the R radicals are independently H or CH3, and the radicals can have the same or different meanings. Mixtures are preferably used that contain molecules in which both radicals are H, molecules in which both radicals are CH3, and molecules in which one radical is H and the other radical is CH3. Such mixtures can be obtained, for example, by reacting 1,3-bis(1-isocyanato-1-methylethyl)benzene with hydroxypropyl methacrylate and 2-hydroxyethyl methacrylate. Tetramethylxylylenediurethane dimethacrylate (R = CH3) is very particularly preferred.

[0028] The urethane dimethacrylate monomers with aromatic groups are preferably used in a total amount of from 5 to 60% by weight, particularly preferably from 10 to 45% by weight, very particularly preferably from 10 to 25% by weight, based on the mass of monomer component (a).

[0029] The compositions according to the invention can further contain one or more hybrid monomers. Preferred monomers of this type are the hybrid monomers disclosed in EP 3 064 192 A1, with monomers containing methacrylamide and methacrylate groups being particularly preferred. Hybrid monomers containing additional urethane groups are very particularly preferred.

[0030] According to the present invention, at least one urethane di(meth)acrylate monomer and / or hybrid monomer having the general formula 1: [ka] (In the formula, R 1 , R 2 = Independently of each other, in each case H2C=C(-R 3 )-C(=O)-O- or H2C=C(-R 4 )-C(=O)-NR 5 - and; R 3 =H or CH3, preferably CH3; R 4 =H or CH3, preferably H; R 5 =H or CH3, preferably CH3; n, m = independently of one another, an integer from 1 to 4, preferably from 1 to 2, particularly preferably 2 in each case. Particularly preferred are dental materials containing those having the formula:

[0031] The monomers of formula 1 are also referred to below as difunctional urethanes.

[0032] Preference is given to difunctional urethanes of the formula 1 having a refractive index of 1.450 to 1.510, particularly preferably 1.460 to 1.505, very particularly preferably 1.460 to 1.500.

[0033] Particularly preferred difunctional urethanes of formula 1 are 2-{[(2-(N-methylacrylamido)-ethoxy)-carbonyl]-amino}-ethyl methacrylate (V850, CAS No.: 2004672-68-6), in particular N-(2-methacryloyloxyethyl)carbamic acid-(2-methacryloyloxyethyl) ester (V837, CAS No.: 139096-43-8): [ka] is.

[0034] The urethanes of Formula 1 are characterized by a significant increase in refractive index during polymerization. For example, the refractive index of V850 changes from 1.500 before polymerization to 1.537 after polymerization, and that of V837 changes from 1.476 before polymerization to 1.518 after polymerization. Therefore, the urethanes of Formula 1 are best suited to increase the refractive index change of a monomer mixture. V850 is further characterized by very low toxicity (cytotoxicity: XTT 50 = 1085.6 μg / mL (L929 mouse cell line); Ames test: negative (Salmonella typhimurium strains TA 1535, TA 1537, TA 98, TA 100, and Escherichia coli WP2 uvrA).

[0035] The difunctional urethanes according to formula 1 are preferably used in a total amount of from 3 to 30% by weight, particularly preferably from 5 to 25% by weight, very particularly preferably from 6 to 20% by weight, based on the mass of monomer component (a).

[0036] In addition to the urethane di(meth)acrylates and difunctional urethanes of formula 1 already mentioned, the dental materials according to the invention can advantageously contain further urethane di(meth)acrylates, preferably urethane dimethacrylates. These are preferably used in amounts of 10 to 70% by weight, particularly preferably 15 to 60% by weight, and very particularly preferably 20 to 47% by weight, based on the mass of the monomer component (a). A preferred urethane dimethacrylate is 7,7(9)9-trimethyl-4,3-dioxo-3,14-dioxa-5,12-diazohexadecane-1,16-diyl dimethacrylate (RM3).

[0037] The total amount of urethane di(meth)acrylate and difunctional urethane of formula 1 is preferably in the range of 20 to 80% by weight, preferably in the range of 30 to 70% by weight, particularly preferably in the range of 40 to 67% by weight, based on the mass of monomer component (a).

[0038] In addition to the monomers listed, monomer component (a) preferably also contains one or more radically polymerizable bisphenol A derivatives, such as 2,2-bis[4-(2-hydroxy-3-methacryloyloxypropyl)phenyl]propane (bis-GMA), preferably bisphenol A dimethacrylate, particularly preferably ethoxylated or propoxylated bisphenol A dimethacrylate, and very particularly preferably 2-[4-(2-methacryloyloxyethoxyethoxy)phenyl]-2-[4-(2-methacryloyloxyethoxy)phenyl]propane (SR-348c, containing three ethoxy groups). Bis-GMA is an addition product of methacrylic acid and bisphenol A diglycidyl ether. Since commercially available bis-GMA is frequently contaminated with bisphenol A, materials free of bis-GMA are preferred according to the present invention.

[0039] The bisphenol A derivatives are preferably used in a total amount of from 10 to 40% by weight, particularly preferably from 12 to 30% by weight, very particularly preferably from 14 to 25% by weight, based on the mass of the monomer component (a).

[0040] Component (a) can advantageously further contain a methacrylate from the group of tricyclic dimethacrylates, in particular tricyclodecane dimethanol dimethacrylate, and very particularly preferably tricyclodecane dimethanol dimethacrylate TCP (CAS number: 42594-17-2). The refractive index of TCP changes from 1.501 to 1.531 during polymerization. The tricyclic dimethacrylate is preferably used in a total amount of 1 to 40% by weight, particularly preferably 5 to 30% by weight, and very particularly preferably 10 to 25% by weight, based on the mass of monomer component (a).

[0041] In addition to the listed monomers, monomer component (a) can advantageously contain one or more so-called chain regulators. These are monomers that control chain growth during polymerization, thereby achieving a reduced shrinkage force. A particularly preferred chain regulator according to the present invention is 2-[(1-ethoxy-2-methyl-1-oxopropan-2-yl)oxy]acrylic acid ethyl ester. Furthermore, the radically polymerizable sulfur-containing monomers disclosed in EP 2 965 741 A1 are preferred, with 2-(toluene-4-sulfonylmethyl)acrylic acid ethyl ester being particularly preferred. The chain regulator is preferably used in an amount of 0 to 8% by weight, particularly preferably 0.1 to 7% by weight, and very particularly preferably 0.5 to 6% by weight, based on the mass of monomer component (a). A low shrinkage force has an advantageous effect on the edge sealing of the filler.

[0042] Finally, the monomer component (a) may contain one or more additional radically polymerizable monomers not included in any of the above groups, for example to set the refractive index. Preferred additional monomers are (meth)acrylamides, such as N-disubstituted (meth)acrylamides, such as N,N-dimethylacrylamide, and bis(meth)acrylamides, such as N,N'-diethyl-1,3-bis(acrylamido)-propane, 1,3-bis(methacrylamido)-propane, 1,4-bis(acrylamido)-butane, and 1,4-bis(acryloyl)piperazine. Monofunctional methacrylates, such as 2([1,1'-biphenyl]-2-oxy)ethyl methacrylate, are more preferred, and polyfunctional, especially difunctional, methacrylates are particularly preferred, such as di-, tri-, or tetraethylene glycol dimethacrylate, trimethylolpropane trimethacrylate, pentaerythritol tetramethacrylate, and glycerol dimethacrylate and trimethacrylate, 1,4-butanediol dimethacrylate, 1,10-decanediol dimethacrylate (D3MA), 1,12-dodecanediol dimethacrylate, and mixtures thereof.

[0043] The monomer 1,10-decanediol dimethacrylate (D3MA) is particularly preferred. It is characterized by a large difference in refractive index between the monomeric and polymeric forms (1.460 to 1.500). Furthermore, it has a very low refractive index, making it particularly suitable for setting the low refractive index of the monomeric component (a).

[0044] Such further monomers are preferably used in a total amount of up to 20% by weight, particularly preferably from 2 to 20% by weight, very particularly preferably from 4 to 10% by weight, based on the weight of monomer component (a).

[0045] The total amount of radically polymerizable monomers is preferably in the range from 5 to 40% by weight, particularly preferably from 10 to 35% by weight, very particularly preferably from 12 to 30% by weight, based on the total mass of the dental material.

[0046] According to the invention, dental materials in which component (a) contains a mixture of the following monomers are particularly preferred: In each case relative to the total mass of component (a) (a-1) from 20 to 80% by weight, preferably from 30 to 70% by weight, very particularly preferably from 40 to 67% by weight, of at least one urethane dimethacrylate, (a-2) 10 to 40% by weight, preferably 12 to 30% by weight, very particularly preferably 14 to 25% by weight of at least one bisphenol A derivative, preferably ethoxylated or propoxylated bisphenol A dimethacrylate, very particularly preferably SR-348c, (a-3) optionally up to 40% by weight, preferably 5 to 30% by weight, very particularly preferably 10 to 25% by weight, of at least one tricyclic dimethacrylate, preferably tricyclodecane dimethanol dimethacrylate (TCP), and (a-4) other monomers, i.e. monomers not included in one of the groups (a-1) to (a-3) and (a-5), preferably D3MA, optionally in an amount of up to 20% by weight, preferably from 4 to 20% by weight, particularly preferably from 4 to 10% by weight, (a-5) optionally up to 8% by weight, preferably 0.1 to 7% by weight, particularly preferably 0.5 to 6% by weight, of at least one chain regulator;

[0047] In all cases, individual monomers or mixtures of several monomers can be used as components (a-1) to (a-5).

[0048] The monomers (a-1) to (a-5) are preferably selected from the substances defined above, with those dental materials in which component (a) contains exclusively the listed monomers being particularly preferred according to the invention.

[0049] As component (a-1), the monomer mixture contains in each case, based on the total weight of the monomer component (a), - 5 to 60% by weight, preferably 10 to 45% by weight, particularly preferably 10 to 25% by weight, of at least one urethane dimethacrylate monomer having aromatic groups, preferably V380, - 3 to 30% by weight, particularly preferably 5 to 25% by weight and very particularly preferably 6 to 20% by weight of at least one difunctional urethane of formula 1, - 10 to 70% by weight, preferably 15 to 60% by weight, particularly preferably 20 to 47% by weight of at least one further urethane dimethacrylate, preferably UDMA Those containing it are preferably used. Radiopaque filler (b)

[0050] The material according to the invention contains as component (b) at least one radiopaque filler, preferably tantalum(V) oxide, barium sulfate, mixed oxides of SiO2 with ytterbium(III) oxide or tantalum(V) oxide, ytterbium trifluoride, or mixtures thereof, with ytterbium trifluoride being particularly preferred.

[0051] The radiopaque filler is present in particulate form, preferably having an average primary particle size of ≦25 nm, particularly preferably 10 to 24 nm, and the particles are present in a non-aggregated and non-agglomerated form. Particles with a particle size of ≦25 nm are referred to herein as nanoscale.

[0052] The material according to the invention very particularly preferably contains YbF3 particles having an average primary particle size of ≦25 nm, preferably from 10 to 24 nm, particularly preferably from 14 to 22 nm, in particular about 20 nm, the particles preferably being present in non-aggregated and non-agglomerated form.

[0053] Unless otherwise indicated, all particle sizes are volume average particle sizes (D50 values, i.e., 50% of the particles are smaller than the stated value). Particle size determination in the range of 0.1 μm to 1000 μm is preferably performed using static light scattering (SLS), for example, using an LA-960 Static Laser Scattering Particle Size Distribution Analyzer (Horiba, Ltd., Japan) or a Microtrac S100 Particle Size Analyzer (Microtrac, USA). In this case, a laser diode with a wavelength of 655 nm and an LED with a wavelength of 405 nm are used as light sources. The use of two light sources with different wavelengths makes it possible to measure the entire particle size distribution of a specimen in just one measurement pass, and this measurement is performed as a wet measurement. For this purpose, an aqueous dispersion of the filler is prepared, and its scattered light is measured in a flow cell. The scattered light analysis to calculate particle size and particle size distribution is performed according to the Mie theory according to DIN / ISO 13320. Measurement of particle sizes in the range of 5 nm to 0.1 μm is preferably carried out by dynamic light scattering (DLS) of aqueous particle dispersions, preferably using a He-Ne laser with a wavelength of 633 nm at a scattering angle of 90° and 25°C, for example using a Malvern Zetasizer Nano ZS (Malvern Instruments, Malvern, UK).

[0054] It has been found that YbF3 particles smaller than 25 nm in size increase the radiopacity of the material while only slightly affecting the refractive index of the composition. Therefore, unlike radiopaque glasses, the use of high-refractive-index monomers is not required to ensure good translucency. The use of nanoscale YbF3 particles obviates the need for barium-containing glasses as radiopaque fillers. Furthermore, nanoscale YbF3 particles advantageously do not cause visible opacification of the paste.

[0055] According to a preferred embodiment, the YbF3 particles are surface-modified. For this purpose, they are preferably treated with an organic compound having a functional group capable of bonding to the surface of the YbF3 particles. Preferred functional groups are phosphate, phosphonate, carboxyl, dithiophosphate, and dithiophosphonate groups. The surface modifier preferably also has a radical polymerizable group that allows crosslinking with the organic component (a).

[0056] Preferred surface modifiers are P-7,10,13,16-tetraoxaheptadec-1-yl-phosphonic acid, P-[6-[2-[2-(2-hydroxyethoxy)ethoxy]ethoxy]hexyl]phosphonic acid, 2,3-di-(methacryloyloxy)-propyl-1-phosphonic acid, 2,3-di-(methacryloyloxy)-propyl-1-bisphosphonic acid, and 3-O-benzyloxy-2-methacryloyloxy-propyl-1-bisphosphonic acid.

[0057] The dental material according to the invention preferably contains 1 to 30% by weight, particularly preferably 3 to 20% by weight, very particularly preferably 6 to 12% by weight, of nanoscale YbF3 particles, based on the mass of the dental material. Inorganic filler (c)

[0058] A preferred inorganic filler (c) is a glass powder, preferably a barium-free glass powder, in particular a strontium-containing glass powder, and / or a zirconium-containing glass powder. A particularly preferred glass is the glass with CAS number 65997-17-3. The glass powder preferably has an average particle size of 0.1 to 5 μm, particularly preferably 0.3 to 2 μm, and particularly preferably 0.4 to 0.9 μm.

[0059] Furthermore, glasses having a refractive index lower than 1.54, particularly preferably lower than 1.52, and very particularly preferably lower than 1.51 are preferred according to the invention. The refractive index of the glass is preferably in the range of 1.49 to 1.54, particularly preferably 1.49 to 1.52, and very particularly preferably 1.49 to 1.51. Surprisingly, these glasses result in particularly good cure depths.

[0060] The inorganic glass is preferably used in an amount of 20 to 80% by weight, particularly preferably 25 to 70% by weight, very particularly preferably 30 to 60% by weight, based on the total mass of the dental material.

[0061] A further preferred inorganic filler (c) is, for example, zirconium silicate, having a primary particle size of 2 to 100 nm, preferably 5 to 60 nm, particularly preferably 10 to 40 nm, and very particularly preferably 20 to 30 nm. The primary particles are spherical and agglomerate to form secondary particles having a size of 0.5 to 20 μm, preferably 1 to 10 μm, particularly preferably 1 to 7 μm, and very particularly preferably 2 to 6 μm. They can be prepared according to U.S. Patent No. 8,617,306 (B2).

[0062] The polishability of the compositions according to the invention can be improved by adding zirconium silicate, whose refractive index is preferably in the range of 1.490 to 1.510. Zirconium silicate is preferably used in an amount of 1 to 30% by weight, particularly preferably 3 to 25% by weight, and very particularly preferably 5 to 20% by weight, based on the total mass of the dental material.

[0063] Furthermore, ZrO2 particles, preferably having an average primary particle size of 0.5 to 50 nm, particularly preferably 1 to 20 nm, very particularly preferably 2 to 10 nm, are preferred as inorganic fillers.

[0064] The radiopacity of the material can be further increased through the addition of ZrO2 particles. ZrO2 particles also result in a significant increase in the refractive index of the material. Therefore, to compensate for this effect, ZrO2 particles are preferably used in combination with a monomer having a low refractive index. Low viscosity methacrylate monomers such as TCP, monomers of Formula 1, and especially D3MA (RI=1.460) are preferred.

[0065] According to a preferred embodiment, ZrO2 particles are suspended in a low-viscosity monomer. For example, 30 to 50 wt. % ZrO2 particles can be suspended in D3MA without significant clouding of the monomer. The refractive index of a suspension in D3MA containing 50 wt. % ZrO2 particles with an average size of 8 nm is, for example, 1.524; the refractive index of a 40 wt. % suspension of particles with an average size of 3 nm is 1.494. Pure ZrO2 has a refractive index of 2.150.

[0066] ZrO2 is preferably used in an amount of 0.3 to 5% by weight, particularly preferably 0.4 to 4% by weight, very particularly preferably 0.5 to 2% by weight, relative to the total mass of the material.

[0067] The total amount of inorganic fillers (c) is preferably from 20 to 90% by weight, particularly preferably from 30 to 70% by weight, very particularly preferably from 40 to 65% by weight, based on the total mass of the dental material.

[0068] To achieve a high cure depth of the dental material according to the invention, the refractive indices of the filler (c) and the monomer component (a) are preferably matched to each other. The latter is preferably set to the same refractive index as the filler (c) or at most 0.03 higher. The refractive index of the monomer component (a) is particularly preferably 0.002 to 0.02 higher, and very particularly preferably 0.05 to 0.015 higher, than the refractive index of the filler (c).

[0069] The material according to the invention can contain a filler or a mixture of fillers as filler (c). When a mixture of fillers is used, the material preferably contains as component (c) mainly, i.e. more than 50% by weight, particularly preferably more than 80% by weight, and very particularly preferably only, fillers whose refractive index is in the ranges listed, based on the total weight of component (c).

[0070] The refractive index is a material constant that depends on the wavelength of light used, temperature, pressure, and purity of the material. Unless otherwise indicated, the refractive index is referred to in all cases herein as the refractive index (n D The refractive index of liquid monomers and monomer mixtures can be determined using commercially available Abbe refractometers.

[0071] The determination of the refractive index (RI) of solid materials, e.g., inorganic or composite fillers, is carried out by the immersion method. The material is dispersed in a mixture of liquids with different refractive indices at room temperature (the so-called immersion liquid). In the process, the outline of the solid particles becomes more clearly visible the greater the difference in refractive index between the liquid and the solid. If the refractive index of the liquid is now changed to approach that of the solid, the outline of the particles becomes weaker and disappears completely when the refractive indices are matched. A liquid with a known refractive index, e.g., benzyl salicylate (n D 20 =1.536) and triacetin (n D 20 =1.431) or bromonaphthalene (n D 20A mixture of these substances (RI = 1.657) is suitable as an immersion fluid. By varying the proportions of these substances, the refractive index of the mixture can be matched to the refractive index of the solid to be measured. When the refractive indices are matched, the refractive index of the immersion fluid is determined using a refractometer.

[0072] To improve the bond between the filler particles and the polymeric matrix, the fillers are preferably surface-modified, particularly preferably by silanization, very particularly preferably with radically polymerizable silanes, in particular 3-methacryloyloxypropyltrimethoxysilane. For surface modification of non-silicate fillers, such as ZrO or TiO, functionalized acid phosphates, such as 10-methacryloyloxydecyl dihydrogen phosphate, can also be used. Composite filler (d)

[0073] The material according to the invention contains at least one composite filler as component (d). Composite fillers are organic polymer particles that are themselves filled with inorganic fillers. Preferred composite fillers have an average particle size of 5 to 100 μm, particularly preferably 15 to 60 μm, and very particularly preferably 20 to 40 μm.

[0074] In the case of composite fillers, the refractive index of the cured polymer matrix is ​​preferably selected to match or differ from the refractive index of the inorganic filler contained therein by at most ±0.2, preferably at most ±0.1, particularly preferably at most ±0.01, so that the particles of the composite filler have high translucency. If more than one inorganic filler is used to prepare the composite filler, the majority of the inorganic fillers, i.e., more than 50% by weight, particularly preferably more than 80% by weight, based on the mass of the inorganic filler, preferably have a refractive index within the recited range.

[0075] The composite filler is preferably prepared by curing a composite paste containing one or more radically polymerizable monomers and one or more inorganic fillers.

[0076] In the preparation of composite fillers, the monomers listed as component (a), the fillers listed as components (b) and (c), and the initiator listed as component (e) are preferred. Such mixtures of components (a), (b), (c), and (e) for the preparation of composite fillers are likewise subject of the present invention.

[0077] Particularly preferred radically polymerizable monomers for the preparation of composite fillers are di(meth)acrylates, in particular very preferably glycerol dimethacrylate (GDMA, RI=1.477), alkylene dimethacrylates such as 1,10-decanediol dimethacrylate (D3MA, RI=1.460) and triethylene glycol dimethacrylate (TEGDMA, RI=1.461), and urethane dimethacrylates such as RM3 and V837, especially urethane dimethacrylates with aromatic groups, particularly preferably V380, and mixtures thereof.

[0078] 1,10-Decanediol dimethacrylate is characterized by a particularly low refractive index (RI). Urethane dimethacrylate RM3, with a refractive index of 1.485, is also among the monomers with low refractive indexes. With a refractive index of 1.513, V380 has a significantly lower refractive index than bis-GMA, with a refractive index of 1.552, yet still exerts its favorable mechanical properties on the composite.

[0079] Preferred fillers for preparing the composite filler are barium-free glass powders, especially strontium glass and / or zirconium-containing glass fillers. Strontium glass fillers are particularly preferred, with strontium glass powders having a particle size of 0.4 to 1 μm being very particularly preferred. Zirconium silicate, as defined above, is even more particularly preferred. Furthermore, the ZrO2 particles and nanoscale ytterbium trifluoride, as defined above, used as component (b), are very particularly preferred inorganic fillers for preparing the composite filler.

[0080] For aggregated or agglomerated particles, the primary particle size can be determined using TEM images. Transmission electron microscopy (TEM) is preferably performed using a Philips CM30 TEM at an accelerating voltage of 300 kV. To prepare the specimen, a droplet of the particle dispersion is deposited on a 50 Å thick copper grid (mesh size 300 mesh), coated with carbon, and then the solvent is evaporated. The particles are counted and the arithmetic mean is calculated.

[0081] The inorganic fillers used to prepare the composite fillers preferably have a refractive index of 1.48 to 1.55, particularly preferably 1.50 to 1.53.

[0082] Composite fillers having the following composition are preferred according to the invention: - 8 to 50% by weight, preferably 10 to 30% by weight, of radically polymerizable monomers, - 1 to 20% by weight, preferably 2 to 15% by weight, of ytterbium trifluoride particles with an average particle size of ≦25 nm, - 40 to 90% by weight, preferably 60 to 80% by weight, of further inorganic fillers, and - 0.01 to 2% by weight, preferably 0.1 to 1% by weight, of an initiator for radical polymerization.

[0083] The percentage values ​​are relative to the total weight of the composite filler.

[0084] The composition can be polymerized, milled, and used as a powder. Polymerization is preferably carried out thermally or photochemically. As a rule, the milled particles have a fragmented shape. The milled composite fillers preferably have an average particle size of 10 to 50 μm, particularly preferably 10 to 40 μm, and very particularly preferably 30 to 40 μm. They preferably contain up to 10 wt.% of particles with an average particle size of <10 μm, based on the mass of the milled composite filler. A preferred composite filler of this type and a process for preparing it are described in EP 1 234 567 A2.

[0085] According to a particularly preferred embodiment, the particles of the composite filler have a spherical shape, and this specification also refers to particles that do not have a perfect spherical shape. Spherical particles can be prepared, for example, using so-called in-flight polymerization (aerosol polymerization). For this purpose, the non-polymerized starting materials for preparing the composite filler are sprayed in the form of droplets into a polymerization chamber, and then polymerized by irradiation with light of a suitable wavelength, preferably light in the blue range. If necessary, the polymerizable mixture can be diluted with a suitable solvent before spraying to set the particle size.

[0086] The photoinitiators listed as component (e) are suitable as initiators for photocuring, in particular 4,4'-dichlorobenzil or its derivatives, and camphorquinone, preferably in combination with amines as accelerators, such as ethyl 4-(dimethylamino)benzoate, and dibenzoylgermanium derivatives, such as bis-(4-methoxybenzoyl)diethylgermanium.

[0087] The spherical composite fillers may also contain the above-mentioned substances as inorganic fillers, with strontium glass fillers, nanoscale YbF3, and / or zirconium silicate, as defined above, being preferred herein. The strontium glass powder preferably has a particle size in the range of 0.4 to 1 μm, particularly preferably 0.5 to 0.8 μm.

[0088] The polymerized spherical composite fillers preferably have an average particle size of from 5 to 100 μm, particularly preferably from 10 to 80 μm, very particularly preferably from 20 to 50 μm.

[0089] Surprisingly, according to the present invention, it has been found that spherical composite fillers (d), especially those containing spherical particles such as zirconium silicate and / or nanoscale radiopaque substances such as YbF3, significantly improve the cure depth and bending strength of dental materials. Furthermore, the addition of spherical composite fillers improves the polishability and gloss stability of dental materials. Furthermore, these fillers improve the handling and stability of pastes.

[0090] The refractive indices of the filler (d) and the monomer component (a) preferably match each other so that the refractive index of component (a) corresponds to the refractive index of the filler (d) or is at most 0.025 greater. The refractive index of the monomer component (a) is preferably at most 0.02, particularly preferably at most 0.01 greater than the refractive index of the filler (d).

[0091] The materials according to the invention can contain fillers or filler mixtures as filler (d). When filler mixtures are used, the materials preferably contain as component (d) mainly, i.e. more than 50% by weight, particularly preferably more than 80% by weight, and particularly preferably exclusively, composite fillers whose refractive indexes satisfy the recited conditions, in each case based on the total mass of component (d).

[0092] The composite filler (d) is preferably used in an amount of 5 to 60% by weight, particularly preferably 10 to 50% by weight, very particularly preferably 15 to 40% by weight, based on the total mass of the dental material. Radical polymerization initiator (e)

[0093] The material according to the invention contains as component (e) at least one initiator for radical polymerization, preferably a photoinitiator.

[0094] Photosensitizers, especially α-diketones such as 9,10-phenanthrenequinone, 1-phenyl-propane-1,2-dione, diacetyl or 4,4′-dichlorobenzil or derivatives thereof, particularly preferably camphorquinone (CQ) and its derivatives, and mixtures thereof, are preferred photoinitiators.

[0095] Photoinitiators are preferably used in combination with accelerators.Tertiary amines, such as tertiary aromatic amines, particularly N,N-dialkyl-aniline, -p-toluidine, or -3,5-xylidine, p-(N,N-dialkylamino)-phenylethanol, benzoic acid derivatives, benzaldehyde, phenylacetic acid esters, and phenylpropionic acid esters are particularly suitable as accelerators.Specific examples thereof are N,N-dimethylaniline, N,N-dimethyl-p-toluidine, N,N,3,5-tetramethylaniline, N,N-dimethylamino-p-benzaldehyde, p-(dimethylamino)-benzoic acid ethyl ester, or p-(dimethylamino)-benzonitrile. Tertiary aliphatic amines, such as tri-n-butylamine, dimethylaminoethan-2-ol, triethanolamine, dimethylaminoethyl methacrylate, N,N-dimethylbenzylamine, or heterocyclic amines, such as 1,2,2,6,6-pentamethylpiperidine and amino acid derivatives, such as N-phenylglycine, are also suitable. Alternatively, amine-free accelerators can be used, such as sulfinic acids and sulfinates, borates, enolates, phosphines, or other compounds containing active hydrogen atoms, such as heterocyclic compounds such as morpholine derivatives or 1,3-dioxolanes.

[0096] Particularly preferred photoinitiators are acyl- or bisacylgermanium compounds, particularly the monoacyltrialkyl- and bisacyldialkylgermanium compounds disclosed in EP 1 905 413 A1, such as benzoyltrimethylgermanium, bisbenzoyldiethylgermanium, or bis(4-methoxybenzoyl)diethylgermanium. Acyl- and bisacylgermanium compounds have the advantage that they decolorize after irradiation (bleaching effect), thus not impairing the transmittance of the cured material. Furthermore, they are unimolecular photoinitiators, i.e., they do not require an accelerator to reach full activity.

[0097] Further particularly preferred photoinitiators are acyl or bisacylphosphine oxides, in particular those described in EP 0 007 505, EP 0 073 413, EP 0 184 095, and EP 0 615 980. Preferred examples are the commercially available compounds 2,4,6-trimethylbenzoyldiphenylphosphine oxide (Lucirin® TPO, BASF) and bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide (Irgacure® 819, Ciba). Acyl and bisacylphosphine oxides also belong to the group of unimolecular photoinitiators and are characterized by low intrinsic absorption.

[0098] The compositions according to the invention, containing one of the listed initiators, can be cured by irradiation, for example, with blue light (wavelength range of 400 to 500 nm), preferably with a power rating of 1200 mW / cm 2 to 3050mW / cm 2 It can be cured by irradiating it with an LED lamp.

[0099] The initiators are preferably used in an amount of 0.005 to 3.0% by weight, particularly preferably 0.01 to 2.0% by weight, particularly preferably 0.1 to 1% by weight, based on the total mass of the dental material. Further components

[0100] The compositions according to the invention may also contain further additives, most notably rheology modifiers, stabilizers such as polymerization stabilizers, colorants, i.e. pigments and / or dyes, antimicrobially active compounds, fluoride ion-releasing additives, optical brighteners, fluorescent agents, UV absorbers, substances for improving fracture toughness, and / or agents. The total amount of additives is preferably at most 4 wt. %, particularly preferably at most 3 wt. %, based on the total mass of the material.

[0101] The dental material according to the invention preferably comprises: - 5 to 40% by weight, preferably 10 to 35% by weight, particularly preferably 12 to 30% by weight, of at least one radically polymerizable monomer (a), - 1 to 30% by weight, preferably 3 to 20% by weight, particularly preferably 6 to 12% by weight, of ytterbium trifluoride particles (b), from 20 to 90% by weight, preferably from 30 to 70% by weight, particularly preferably from 40 to 65% by weight, of inorganic fillers (c), - 5 to 60% by weight, preferably 10 to 50% by weight, particularly preferably 15 to 40% by weight, of composite filler (d), and - 0.005 to 3.0% by weight, preferably 0.01 to 2.0% by weight, particularly preferably 0.1 to 1% by weight, of initiators (e) for radical polymerization Contains:

[0102] Dental materials having the following composition are particularly preferred: - 12 to 30% by weight of a radically polymerizable monomer (a), - 3 to 10% by weight of ytterbium trifluoride particles (b), - 45 to 65% by weight of inorganic filler (c), - 15 to 40% by weight of a composite filler (d), and - 0.01 to 0.5% by weight of an initiator for radical polymerization (e).

[0103] The percentage values ​​are in each case relative to the total mass of the dental material.

[0104] The amount specified for component (b) does not include ytterbium trifluoride optionally contained in component (d).

[0105] Of course, it is preferred that these materials are selected from the preferred and particularly preferred materials for components (a) to (e) defined above.

[0106] Highly preferred are materials in which monomer component (a) contains, in each case based on the total mass of monomer component (a), 1 to 25 wt. %, preferably 2 to 20 wt. %, and particularly preferably 5 to 12 wt. % of V850 and / or V837; 1 to 60 wt. %, preferably 5 to 30 wt. %, and particularly preferably 10 to 25 wt. % of a urethane dimethacrylate containing aromatic groups, preferably V380; and 1 to 70 wt. %, preferably 2 to 66 wt. %, and particularly preferably 5 to 46 wt. % of a further urethane dimethacrylate, preferably RM3. Monomer component (a) preferably further contains 2 to 40 wt. %, preferably 4 to 30 wt. %, and particularly preferably 6 to 25 wt. % of SR348C. Furthermore, monomer component (a) preferably further contains 2 to 40 wt. %, preferably 7 to 30 wt. %, and particularly preferably 10 to 25 wt. % of TCP.

[0107] The dental material according to the invention preferably contains a total of 30 to 95% by weight, particularly preferably 50 to 90% by weight, very particularly preferably 65 to 85% by weight of fillers (components (b), (c), and (d)), based on the total mass of the dental material.

[0108] The dental material according to the present invention is characterized by high radiopacity, which allows clear differentiation from natural tooth material. Radiopacity is determined according to ISO standard 4049. Here, test specimens made of polymerized dental material together with an aluminum step wedge with a step height of 1 mm were photographed using an X-ray camera. The image darkness was compared, and radiopacity was expressed in Al%; 100% radiopacity corresponds to the darkness of 1 mm of aluminum. The material according to the present invention preferably has a radiopacity of 140% to 350% Al, particularly preferably 160% to 250% Al.

[0109] Radiopacity is preferably achieved through the addition of nanoscale YbF3 particles having an average particle size of ≦25 nm (component b). Particularly preferred dental materials are those in which the composite filler (d) also contains nanoscale YbF3 particles having an average particle size of ≦25 nm. The dental material according to the invention preferably contains, as a whole, i.e., in components (b) and (d), 2 to 30 wt. %, particularly preferably 3 to 20 wt. %, and very particularly preferably 4 to 12 wt. % of nanoscale YbF3, based on the total mass of the material.

[0110] The dental materials according to the invention are further characterized by a large cure depth, which is determined according to DIN EN ISO 4049:2018-04 and is preferably 3 mm or more, particularly preferably 3.5 to 5 mm. These cure depths are achieved after a short exposure time of only 3 seconds (3050 mW / cm 2 ) can be advantageously achieved with the material according to the invention.

[0111] A particular advantage of the dental materials according to the present invention is their excellent aesthetic properties. They make it possible to produce aesthetically pleasing dental restorations in all respects using only one material. It is not necessary to combine several materials together to produce an attractive restoration. Furthermore, the entire naturally occurring color space of human teeth can be covered with only a few shades.

[0112] This effect is achieved through a specific ratio of contrast value (CR value) to transmittance. The dental materials according to the invention preferably have a CR value of 60 to 75, particularly preferably 62 to 70, and very particularly preferably 64 to 68. The transmittance of the colored material is preferably between 8 and 25%, particularly preferably between 9 and 22%, and very particularly preferably between 10 and 18%. All data refer to the hardened material.

[0113] The CR value refers to the ratio of transmittance measurements against a white and black background. This value is also called opacity. The contrast value CR is determined in accordance with BS 5612 (British Standard) using a spectrophotometer (e.g., Minolta CM-3700d). The determination of the contrast value consists of two individual measurements. For this purpose, the specimen to be analyzed is placed in front of a black ceramic body with a maximum reflectance of 4% and then in front of a white ceramic body with a minimum reflectance of 86%, which are then analyzed colorimetrically. When highly transparent specimens are used, reflection / absorption is mainly caused by the ceramic background, whereas reflection by the specimen is caused when an opaque material is used. The ratio of the reflected light in front of a black background to the reflected light in front of a white background is a measure of the contrast value, with perfect transmission resulting in a contrast value of 0 and perfect opacity resulting in a contrast value of 100.

[0114] The interplay between CR value and transmittance results in materials with outstanding aesthetic properties. Transmittance in the range according to the invention allows ambient light to penetrate the material, making it appear lifelike. At the same time, materials with CR values ​​according to the invention allow the color of the surrounding hard dental tissue to be emitted and refracted within the material, making the material appear to have a color similar to that of the hard dental tissue.

[0115] As a result of these properties, the material according to the present invention can completely cover the color space of natural tooth colors, which usually includes the 16 shades of the VITA Classical A1-D4® Shade Guide, along with several shades. In the case of the material according to the present invention, each shade covers several shades of the usual 16 shades, but this is due to the combination of a defined CR value and a defined transmittance with its specific shade and brightness settings. The material blends ideally into natural teeth, because on the one hand it takes on the color of the surrounding hard dental tissue, and at the same time it has sufficient color and opacity to avoid a neutral appearance.

[0116] The dental materials are suitable for intraoral application by dentists, in particular as dental cements, coatings or veneering materials, and very particularly as filling composites and so-called bulk-fill composites, primarily for the restoration of damaged teeth (therapeutic application).

[0117] The materials according to the present invention have high stability, low adhesion, and are fillable. This means that they can be processed and introduced into a cavity and compacted in the same way as amalgam. Therefore, they are particularly suitable as dental filling materials for filling all types of anterior and posterior teeth directly and indirectly. These properties are achieved by selecting the monomer, the type of filler according to the present invention, and the amount of filler.

[0118] The dental materials according to the present invention are characterized by an advantageous combination of properties. The present invention allows the preparation of materials with a high filler content, which is advantageous for dental filling materials, without compromising the depth of cure and aesthetic properties of the material. Due to their optical properties, the materials according to the present invention can therefore be very successfully cured using light in large layer thicknesses. They are therefore particularly suitable for use as bulk-fill composites. By bulk-fill composite, we mean dental filling materials that can be cured using light in layers with a thickness of more than 3 mm, preferably more than 4 mm, and in particular 4 to 5 mm. This allows for even larger tooth fillings to be achieved with just one or two layers.

[0119] The materials according to the invention can also be used extraorally (non-therapeutically), for example for the production or repair of dental restorations (non-therapeutic applications). They are particularly suitable as materials for producing inlays, onlays, crowns or bridges. The invention will now be explained in more detail with the aid of figures and examples: [Brief explanation of the drawings]

[0120] [Figure 1] Figure 1 shows a class 2 cavity in a human molar with a darkly stained cavity floor.

[0121] [Figure 2] FIG. 2 shows the human molar from FIG. 1 filled with the dental material according to the invention from Example 6.

[0122] [Figure 3] FIG. 3 shows a scanning electron micrograph of the spherical particles from Example 8.

[0123] [Figure 4] Figure 4 shows a bleached human anterior tooth with Class 3 mesio-buccal and distal-buccal fillings placed using the dental material from Example 10. The fillings blend naturally into the interior of the tooth and are practically invisible.

[0124] [Figure 5] Figure 5 shows a human anterior tooth with Class 3 mesio-buccal and distal-buccal fillings placed using the dental material from Example 14. The fillings blend naturally into the interior of the tooth and are practically invisible. [Example]

[0125] Dental materials were prepared using the formulations shown in the following embodiment examples and tested as described. The components were mixed together using a magnetic stirrer, a kneader (LPM 0.5 SP machine, manufactured by Linden), or a centrifugal mixer (Speedmixer DAC 600.2, manufactured by Hauschild).

[0126] To determine the transmittance of the material, cured rounded specimens (diameter: 20 mm, h = 1 mm) were produced and measured colorimetrically with the aid of a spectrophotometer (CM-5 spectrophotometer, Minolta). Polymerization was initiated by a LED lamp (3 s, 3050 mW / cm). 2 ) was performed.

[0127] Measurements of flexural strength and depth of cure were performed according to ISO 4049:2009: Dentistry - Polymer-based restorative materials. The values ​​stated here for depth of cure (DOC) correspond to half of the measured value. A measurement of DOC / 2 ≥ 3.5 mm means that the material may be said to be bulk-fillable, and a depth of cure of at least 4 mm is considered to be guaranteed under dental conditions.

[0128] The Vickers hardness was determined using a Vickers hardness tester from Zwick (ZHV 0.2). In addition, the case depth (in mm) at which the Vickers hardness of polymerized specimens that have been crushed transversely to the middle still reaches 80% of the surface hardness is shown.

[0129] Radiopacity and CR values ​​were determined using the techniques described in the description. In the examples, the following materials were used: Accelerator: Ethyl 4-(dimethylamino)benzoate (CAS No. 10287-53-3) Bis-GMA Bisphenol A Glycidyl Methacrylate (CAS No. 1565-94-2) BHT Butylhydroxytoluene TCP tricyclodecane dimethanol diacrylate (CAS No. 42594-17-2) D3MA 1,10-Decanediol Dimethacrylate MA836 2-([1,1'-biphenyl]-2-oxy)ethyl methacrylate Ge Photoinitiator Bis(4-methoxybenzoyl)diethylgermanium (CAS No. 1469766-31-1) Phosphine Oxide Diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide (photoinitiator) Glass Filler 1: Barium-free Sr-, Al-, and F-containing dental glass with 6% silanization, an average particle size of 0.7 μm, and a refractive index of 1.50 (glass G018-163). Glass Filler 2: Radiopaque dental glass powder, 6% silanized, refractive index 1.50 (Schott glass G018-430) Chain regulator 2-(toluene-4-sulfonylmethyl)acrylic acid ethyl ester RM3 7,7(9)9-trimethyl-4,3-dioxo-3,14-dioxa-5,12-diazohexadecane-1,16-diyl dimethacrylate Zirconium silicate spherical zirconium silicate particles, average primary particle size: 20 nm, secondary particle size: 3.44 μm, refractive index: 1.50 SR-348C Ethoxylated Bisphenol A Dimethacrylate (CAS No. 41637-38-1) V380 Aromatic urethane dimethacrylate V850 Methacrylic acid-2-{[2-(N-methylacrylamido)-ethoxycarbonyl]-amino}-ethyl ester nYbF3 nanoscale ytterbium trifluoride, average particle size 14nm YbF3 powdered ytterbium trifluoride, average particle size 100nm Non-agglomerated ZrO2 particles with a primary particle size of 8 nm V837 N-(2-methacryloyloxyethyl)carbamic acid-(2-methacryloyloxyethyl) ester (CAS No. 139096-43-8) Example 1 Preparation of Composite Filler (Comparative Example)

[0130] A composite material having the composition shown in Table 1 was prepared by the method described in Example 1 of EP 1 234 567 A2. The material was heat cured, then coarsely crushed, and then milled using a ball mill to an average particle size of 25 μm. The refractive index of the monomer mixture used was 1.484 before polymerization and 1.509 after polymerization. The refractive index of the composite filler was 1.506. [Table 1]

[0131] Example 2 Preparation of radiopaque composite fillers A composite material having the composition shown in Table 2 was prepared by the method described in Example 1 of EP 1 234 567 A2. To this end, the monomers were first mixed together, and then ytterbium trifluoride was incorporated into a portion of the monomer mixture. This was mixed with the remaining monomers, after which the glass filler was homogeneously incorporated into the resulting mixture. The material was heat-cured, then coarsely crushed, and then milled using a ball mill to an average particle size of 25 μm. The refractive index of the monomer mixture used was 1.482. After polymerization, the refractive index was 1.514. The composite filler had a refractive index of 1.506. [Table 2]

[0132] Example 3 Dental material based on composite filler from Example 1 (comparative example)

[0133] To prepare the dental material with the composition shown in Table 3, the listed monomers were first mixed with each other for 12 hours to dissolve all of the components. The powdered components were then added and mixed homogeneously using a mixer (Speedmixer DAC 600.2 VAC-P, manufactured by Hauschild) to form a paste. The refractive index of the uncured monomer mixture was 1.510. [Table 3]

[0134] Depth of cure (DOC / 2), transmittance, flexural strength, modulus, and radiopacity were measured as described above and the results are shown in Table 5. Example 4 Dental material based on composite filler from Example 2

[0135] In preparing the dental material of the composition shown in Table 4, the listed monomers were first mixed homogeneously with stirring, and then YbF3 was incorporated into a portion of the mixture, resulting in a clear liquid. The remaining monomers were then added, followed by the powdered ingredients, and mixed homogeneously to form a paste. The YbF3-rich filler from Example 2 was used as the composite filler. The refractive index of the uncured monomer mixture was 1.508. [Table 4]

[0136] The materials were analyzed as described above and the results are shown in Table 5. [Table 5]

[0137] Table 5 shows that the addition of nanoparticulate YbF3 does not have a negative effect on the paste properties. The paste according to the invention has a high cure depth and transmittance despite a significantly higher radiopacity. Example 5 Dental material based on composite filler from Example 2

[0138] To prepare the dental material with the composition shown in Table 6, the monomers bis-GMA, RM3, and Sr-348C were first mixed homogeneously with stirring, and then YbF3 was incorporated into the mixture, resulting in a clear liquid. The refractive index of this mixture was 1.509 before polymerization and 1.533 after polymerization. The difference between these values ​​was 0.024. The remaining monomers, followed by the powdered components, were then added and mixed homogeneously to form a paste.

[0139] The materials were analysed as described above and the results are shown in Table 7. All values ​​exceed the requirements of dental standard EN-ISO 4049. [Table 6] [Table 7]

[0140] Example 6 Coloring of dental material from Example 5 The composite paste from Example 5 was adjusted to the following L, a, b, and CR values ​​by the stepwise addition of the pigment Sicotrans Red and mixed vigorously: The paste was then degassed for 5 minutes in a centrifugal mixer (SpeedMixer, Hauschild & Co. KG, Germany) at 23,500 rpm and 100 mbar. [Table 26]

[0141] The color is L according to DIN EN ISO 11664-4 * a * b * The color was determined by a color model. Color measurements were performed using a commercially available measuring instrument (Minolta CM-3700d spectrophotometer). The depth of cure (DOC / 2) was 3.7 mm.

[0142] To check the covering behavior, an extracted human molar corresponding to Vita shade A3.5 was drilled, and the cavity bottom was stained grayish-black using two free-flowing effect materials (Empress Direct Color Gray and Empress Direct Color Brown; manufactured by Ivoclar Vivadent AG). Figure 1 shows the stained cavity bottom, and Figure 2 shows the same tooth filled with the dental material. The discoloration is barely visible; the tooth looks very natural. As a result of the good cure depth, the material can cure in one layer within a 4 mm deep cavity. Example 7 Comparison of nanoscale and conventional YbF3-containing dental materials

[0143] Materials having the compositions shown in Table 8 (Materials A and C) were prepared by the method described in Example 3. In parallel, a radiopaque dental material (Material B) having the composition also shown in Table 8 was prepared by the method described in Example 5. The materials were analyzed by the methods described above. The results are shown in Table 9. [Table 8]

[0144] The above materials have similar compositions, with the difference being that Material A does not contain YbF3, Material B contains nanoscale YbF3 (nYbF3), and Material C contains YbF3 powder with an average particle size of 100 nm. Materials A and B have comparable depths of cure (DOC / 2) of 4.3 mm and 4.2 mm, respectively. This indicates that the addition of nanoscale YbF3 does not significantly impair the depth of cure. Therefore, a sufficiently wide range exists for coloring the materials. Pigments and other dyes can be added up to the threshold for bulk-fill materials of 3.5 mm. In contrast, Material C only has a DOC / 2 of 3.8 mm, leaving only a small range available for coloring. The cloud effect of the larger YbF3 particles becomes apparent here. Furthermore, the difference in transmittance before and after curing is significantly lower for Material C than for Material B, which is preferred in accordance with the present invention. Therefore, Material C is less well suited as a bulk-fill material. In contrast, a comparison of materials A and B shows that the addition of nanoscale YbF3 has only a small effect on the difference in transparency before and after curing, indicating that nanoscale ytterbium fluoride is best suited to increasing radiopacity without significantly impairing the optical properties of the material. [Table 9]

[0145] Example 8 Preparation of composite fillers with spherical particles

[0146] To prepare the composite filler with the composition shown in Table 10, the listed monomers were first mixed together, and then zirconium silicate was incorporated into the monomer mixture. The dispersion was carried out in a glass cylinder with gentle stirring for 6 to 24 hours. 0.3 wt. % camphorquinone and 0.6 wt. % ethyl 4-(dimethylamino)benzoate were then added, followed by further stirring until the initiator components were dissolved. The mixture was then pumped at 20 ml / min into a spray nozzle operated at 2.1 bar pressure under nitrogen. The finely atomized droplets were polymerized using six 100-watt LED lamps with a wavelength of 470 nm. The size of the cured particles was determined using laser diffraction (Microtrac X100 particle size analyzer). The particles had a spherical structure and an average particle size of 20 μm. The particle size could be controlled by adding acetone (0 to 25%) to the monomer mixture before spraying. Figure 4 shows a scanning electron micrograph of the spherical particles. The composite filler had a refractive index of 1.506. [Table 10]

[0147] Example 9 Preparation of radiopaque composite fillers with spherical particles. Similar to the procedure described in Example 8, spherical composite fillers were prepared with the compositions described in Table 11. The fillers further contained nanoscale YbF3 particles. To prepare the composite fillers, the monomers listed in the table were mixed together, followed by ytterbium trifluoride, after which additional fillers were incorporated into the monomer mixture. The monomer mixture had a refractive index of 1.478, and the refractive index of a mixture made of 50% monomer mixture and 50% YbF3 was 1.481. The refractive index of YbF3 was 1.54. [Table 11]

[0148] Example 10 Dental material based on composite filler from Example 8 In preparing dental materials with the compositions shown in Table 12, the listed monomers were first mixed homogeneously with stirring, and then YbF3 was incorporated into a portion of the mixture, resulting in a mostly clear liquid. The remaining monomers were then added, followed by the powdered ingredients, and mixed homogeneously to form a paste. The materials were analyzed using the techniques described above. The results are shown in Table 13.

[0149] The paste has a very good case depth, which is reflected by a good value of about 7 mm at 80% Vickers hardness. This type of paste can be pigmented without any problems without losing its bulk-fill properties. Compared to Example 5, a significant improvement in flexural strength could be achieved by using the spherical composite filler from Example 8 instead of the milled composite filler from Example 2. [Table 12] [Table 13]

[0150] Example 11 Bis-GMA-free dental material based on composite filler from Example 9 To prepare a bis-GMA-free dental material of the composition shown in Table 14, the monomers listed in the table were first mixed together, and then ytterbium trifluoride was incorporated into the monomer mixture. The powdered ingredients were then added and mixed homogeneously to form a paste. The material was analyzed as described above. The results are shown in Table 15. [Table 14] [Table 15]

[0151] The paste has very good flexural strength and excellent cure depth. The large difference in transmittance before and after cure allows light to penetrate deep into the initially very transparent paste and harden the test specimens even to that depth. After curing, the material has a lower transmittance, which is therefore advantageous for aesthetic reasons. Example 12 Coloring of the paste from Example 11 in shade bleach

[0152] The composite paste from Example 11 was set to the following L, a, b, and CR values ​​by adding white pigment in stages: The transmittance, cure depth, and Vickers hardness were then measured. [Table 27]

[0153] DOC / 2 achieves compliance with the standard, and at a depth of 5.5 mm the material still has 80% of the surface hardness.

[0154] Figure 4 shows a bleached human anterior tooth with Class 3 mesiobuccal and distobuccal fillings placed using a colored composite paste. The fillings blend naturally into the interior of the tooth. They are only fully visible under magnification. At a talking distance, the fillings are invisible.

[0155] Filling materials with bleach shades are suitable for very bright teeth, such as baby teeth or bleached teeth. Because staining with bleach shades requires a significant amount of white pigment to create a bright impression, it results in a greater loss in cure depth than other shades that require less pigment. For this reason, materials with this staining typically have only a low cure depth. The above results show that with this shade, the material according to the present invention has a relatively high cure depth, sufficient for use as a bulk fill material. Therefore, it is also possible to produce other shades with sufficient cure depth. Example 13 Composite filler from Example 9 and ZrO2-based dental material

[0156] The dental material of the composition shown in Table 16 was prepared in the same manner as in the previously described examples. In addition, the monomer mixture contained the monomer D3MA. ZrO2 was suspended in D3MA, and this suspension was then mixed with the other components. The paste was heated to 3050 mW / cm 2 The mixture was polymerized at RT for 3 seconds and then analyzed as described in Example 3. The results are shown in Table 17.

[0157] The composite paste has good cure depth. The transmittance is lower compared with Example 8. Furthermore, the CR value can be increased through the increased content of YbF3 and the addition of ZrO2. [Table 16] [Table 17]

[0158] Example 14 Coloring the paste from Example 13 in a shade appropriate for dark teeth The composite paste from Example 13 was set to the following L, a, b, and CR values ​​by stepwise addition of the pigments Sicotrans Red and Xerogel Yellow: Transmittance, depth of cure, and Vickers hardness were then measured. [Table 28]

[0159] DOC / 2 achieves compliance with the standard, and at a depth of 5.5 mm the material still has 80% of the surface hardness.

[0160] Figure 5 shows a human anterior tooth that would normally be restored with a shade A3.5 filling (Vita shade series), including Class 3 mesiobuccal and distobuccal fillings placed using a colored composite paste. The fillings blend naturally into the tooth. They are only fully visible under magnification. At a talking distance, the fillings are invisible.

[0161] Dental materials intended for dark teeth require a relatively large amount of pigment to set the shade. For this reason, such materials usually have only a low cure depth. The above results show that the material according to the present invention has a relatively high cure depth, which is sufficient for use as a bulk fill material. Therefore, it is also possible to produce other shades with sufficient cure depth. Example 15 Composite filler from Example 9 and zirconium silicate based dental material

[0162] Similar to Example 13, dental materials were prepared that additionally contained zirconium silicate as a filler and a higher percentage of ZrO2. The composition is shown in Table 18. The paste was applied at 3050 mW / cm 2 The composite was polymerized at RT for 3 seconds and then analyzed as described in Example 3. The results are shown in Table 19. The measurements identify the composite as a bulkable paste with good radiopacity. [Table 18] [Table 19]

[0163] Example 16 Materials with various particle sizes of YbF3 Three pastes were prepared with the composition shown in Example 15, where the YbF3 used in Example 15 was replaced in each case by YbF3 with different particle sizes: Paste A: 20 nm, Paste B: 40 nm, and Paste C: 60 nm. A cure depth DOC / 2 of 4.4 mm could be achieved with Paste A. The coarser particles resulted in a cure depth of only 3.8 mm.

[0164] Example 17 Bis-GMA-free dental material based on composite filler and ZrO2 from Example 9 To prepare the bis-GMA-free dental material of the composition shown in Table 20, the monomers listed in the table were first mixed together, and then ytterbium trifluoride was incorporated into the monomer mixture. The powdered ingredients were then added and mixed homogeneously to form a paste. The material was analyzed as described above. The results are shown in Table 21.

[0165] The paste exhibits very good reduction in transmittance during polymerization and high values ​​of cure depth at 80% hardness, and is therefore excellently suitable as a bulk fill material. [Table 20] [Table 21] Example 18 Dental materials based on alternative monomer mixtures

[0166] To produce a dental material of the composition shown in Table 22, the monomers listed in the table were first mixed together, and then ytterbium trifluoride was incorporated into the monomer mixture. The powdered ingredients were then added and mixed homogeneously to form a paste. The material was analyzed as described above. The results are shown in Table 23. The refractive index of the uncured monomer mixture was 1.508. The refractive index of the filler was 1.50.

[0167] The paste showed good reduction in transmittance upon polymerization and very high values ​​for cure depth at 80% hardness. [Table 22]

[0168] [Table 23]

[0169] Example 19 Dental materials with monomer MA836 To produce a dental material of the composition shown in Table 24, the monomers listed in the table were first mixed together, and then ytterbium trifluoride was incorporated into the monomer mixture. The powdered ingredients were then added and mixed homogeneously to form a paste. The material was analyzed as described above. The results are shown in Table 25. The refractive index of the uncured monomer mixture was 1.511. The refractive index of the filler was 1.50.

[0170] The pastes show a very high decrease in transmittance upon polymerization combined with very high values ​​for the cure depth at 80% hardness. [Table 24] [Table 25]

Claims

1. A dental material, comprising: (a) at least one radically polymerizable monomer, said at least one radically polymerizable monomer comprising 20 to 80 weight percent of at least one urethane dimethacrylate; (b) at least one radiopaque filler, the at least one radiopaque filler being ytterbium trifluoride having a volume average particle size (D50 value) of ≦25 nm as measured using dynamic light scattering of an aqueous particle dispersion; (c) at least one inorganic filler; (d) at least one composite filler, and (e) at least one initiator for radical polymerization Including, The refractive index of the monomer component (a) is equal to or greater than the refractive index of the filler (c) by a maximum of 0.03, and the refractive index of the monomer component (a) is equal to or greater than the refractive index of the filler (d) by a maximum of 0.

025. A dental material characterized by:

2. 2. The dental material of claim 1, comprising as component (d) a composite filler with spherical particles.

3. 1,6-bis-[2-methacryloyloxyethoxycarbonylamino]-2,2,4-trimethylhexane (RM3), N-(2-methacryloyloxyethyl)carbamic acid-(2-methacryloyloxyethyl) ester (V837), tetramethylxylylenediurethane dimethacrylate (V380), bisphenol A dimethacrylate, 2,2-bis[4-(2-hydroxy-3-methacryloyloxypropyl)phenyl]propane (bis-GMA), ethoxylated or propoxylated bisphenol A dimethacrylate Methacrylate, bisphenol A dimethacrylate 2-[4-(2-methacryloyloxyethoxyethoxy)phenyl]-2-[4-(2-methacryloyloxyethoxy)phenyl]propane) (SR-348c, 3 ethoxy groups), 2,2-bis[4-(2-methacryloxypropoxy)phenyl]propane, 2-{[(2-(N-methylacrylamido)-ethoxy)-carbonyl]-amino}-ethyl methacrylate (V850), bis-(3-methacryloyloxymethyl)tricyclo-[5.2.1.0 ２，６ ] decane (TCP), 1,10-decanediol dimethacrylate (D ３ 3. The dental material according to claim 1, which comprises as radically polymerizable monomer (a) one of: 2-([1,1'-biphenyl]-2-oxy)ethyl methacrylate; ... and 2-([1,1'-biphenyl]-2-oxy)ethyl methacrylate.

4. Relative to the total mass of the component (a), (a-1) 20 to 80% by weight of at least one urethane dimethacrylate; (a-2) 10 to 40% by weight of at least one bisphenol A derivative 4. Dental material according to claim 1, which comprises as radically polymerizable monomer (a) a mixture of

5. General formula 1: 【Chemistry 4】 (In the formula, R １ , R ２ = independently of each other, H ２ C=C(-R ３ )-C(=O)-O- or H ２ C=C(-R ４ )-C(=O)-NR ５ -; R ３ = H or CH ３ ; R ４ = H or CH ３ ; R ５ = H or CH ３ ; n, m = independently an integer from 1 to 4 5. Dental material according to claim 1, comprising at least one difunctional urethane of the formula:

6. Relative to the total mass of the monomer component (a), - 5 to 60% by weight of at least one urethane dimethacrylate monomer having aromatic groups, - 3 to 30% by weight of at least one difunctional urethane of formula 1, - 10 to 70% by weight of at least one further urethane dimethacrylate The dental material according to claim 5, comprising, as component (a-1), a monomer mixture containing:

7. 7. The dental material according to claim 1, comprising as radiopaque filler (b) ytterbium trifluoride having a volume average particle size (D50 value) of 10 to 24 nm as measured using dynamic light scattering of an aqueous particle dispersion.

8. glass powders with a volume-average particle size (D50 value) of 0.1 to 5 μm, and / or one or more zirconium silicates, and / or - ZrO ２ particle as an inorganic filler (c), 8. The dental material according to claim 1, wherein the volume average particle size is measured using dynamic light scattering of an aqueous particle dispersion, respectively.

9. 9. A dental material according to claim 1, containing a composite filler (d), the composite filler (d) itself containing ytterbium trifluoride particles and / or spherical particles having a volume average particle size (D50 value) of ≦25 nm as measured using dynamic light scattering of an aqueous particle dispersion.

10. relative to the mass of the dental material - 5 to 40% by weight of at least one radically polymerizable monomer (a), - 1 to 30% by weight of ytterbium trifluoride particles (b), - 20 to 90% by weight of an inorganic filler (c), - 5 to 60% by weight of a composite filler (d), and - 0.005 to 3.0% by weight of an initiator (e) for radical polymerization 10. The dental material according to claim 1, comprising:

11. of the total mass of said dental material - 12 to 30% by weight of a radically polymerizable monomer (a), - 3 to 10 wt. % of ytterbium trifluoride particles (b) having a volume average particle size (D50 value) of ≦25 nm, measured using dynamic light scattering of an aqueous particle dispersion; - 45 to 65% by weight of inorganic fillers (c), - 15 to 40% by weight of a composite filler (d), and - 0.01 to 0.5% by weight of said initiator for radical polymerization (e) The dental material of claim 10, comprising:

12. 12. The dental material according to claim 10 or 11, further comprising up to 4% by weight of an additive, based on the total mass of the dental material.

13. 13. Dental material according to any one of claims 1 to 12, having a radiopacity of 140% to 350% Al.

14. 14. Dental material according to any one of claims 1 to 13, having a contrast value (CR value) of 60 to 75 and a transmittance of 8 to 25%.

15. A dental material, comprising: (a) at least one radically polymerizable monomer; (b) ytterbium trifluoride as a radiopaque filler, having a volume average particle size (D50 value) of ≦25 nm as measured using dynamic light scattering of an aqueous particle dispersion; (c) at least one inorganic filler; (d) at least one composite filler, and (e) at least one initiator for radical polymerization Including, The dental material is (a-1) 20 to 80% by weight of at least one urethane dimethacrylate; (a-2) 10 to 40% by weight of at least one bisphenol A derivative The composition contains a radical polymerizable monomer (a) comprising a mixture of The refractive index of the monomer component (a) is equal to or greater than the refractive index of the filler (c) by a maximum of 0.03, and the refractive index of the monomer component (a) is equal to or greater than the refractive index of the filler (d) by a maximum of 0.

025. A dental material characterized by:

16. 16. Dental material according to any one of claims 1 to 15 for therapeutic application as a dental cement, coating or veneer material.

17. 16. Non-therapeutic use of a dental material according to any one of claims 1 to 15 for producing inlays, onlays, crowns and bridges.

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