Dental composition

Abstract

The invention relates to a dental composition comprising: at least one polymerizable monomer having at least one ethylenically unsaturated group; and a free radical initiator system comprising a photosensitizer having an absorption maximum of 400 nm to 800 nm; and at least one thiophenium compound as a co-initiator.

Description

Technical Field

[0001] The present invention relates to a dental composition comprising: at least one polymerizable monomer having at least one ethylenically unsaturated group; and a free radical initiator system comprising a photosensitizer having an absorption maximum between 400 nm and 800 nm; and at least one coinitiator compound. Background Art

[0002] Dental restoration often involves photocurable dental compositions containing free-radically polymerizable resins. Photocuring of dental compositions involves a photoinitiator system that generates free radicals upon exposure to visible light. Typically, photosensitizers such as camphorquinone (CQ), optionally in combination with aromatic tertiary amines, are used as photoinitiator systems.

[0003] However, the presence of amines in compositions containing (meth)acrylates can cause yellowing in the resulting photocurable compositions. Another disadvantage of aromatic tertiary amines is their tendency to discolor and their sensitivity to strongly acidic media. In addition, aromatic tertiary amines react with oxygen free radicals. Therefore, although it is beneficial that their use avoids sticky surfaces on the one hand, on the other hand, compared to the stoichiometric requirements for corresponding photosensitizers such as CQ, initiation requires more aromatic amine. The use of tertiary amines as co-initiators in dental compositions may cause leaching of the cured composition, which may lead to toxicological concerns. Toxicological concerns about aromatic tertiary amines particularly require the development of new co-initiators for photosensitizers such as CQ in dental materials.

[0004] Purpose of the Invention

[0005] In view of the prior art, it was therefore an object of the present invention to provide a novel dental composition comprising an initiator system which should not exhibit the above-mentioned disadvantages of the known prior art dental compositions.

[0006] In particular, the object of the present invention is to provide a dental composition comprising a free-radical initiator system which is at least substantially free of amines, preferably completely free of amines, in particular tertiary amines, more in particular aromatic tertiary amines.

[0007] Therefore, there is a need for a way to provide new co-initiators for common photosensitizers such as camphorquinone in dental compositions, wherein the co-initiator does not contain amines.

[0008] Furthermore, the present invention aims to provide a dental composition comprising a free radical initiator system containing a combination of a photosensitizer and at least one specific amine-free co-initiator, wherein the inventive dental composition reduces or ideally avoids or eliminates the leaching problems and toxicological concerns of conventional co-initiators based on aromatic tertiary amines while at the same time improving the desired biocompatibility. Summary of the Invention

[0009] These objects as well as further objects which are not explicitly stated but which can be immediately inferred or discerned from the connections discussed herein by means of the introduction are achieved by a dental composition having all the features of claim 1. Suitable modifications of the dental composition are protected in the dependent claims 2 to 15.

[0010] Therefore, the present invention provides a dental composition comprising:

[0011] a) at least one polymerizable monomer having at least one ethylenically unsaturated group; and

[0012] b) a free radical initiator system comprising:

[0013] i. a photosensitizer having an absorption maximum of 400 nm to 800 nm; and

[0014] ii. at least one coinitiator compound;

[0015] It is characterized by:

[0016] At least one coinitiator compound is a thiophenium salt composed of a thiophenium cation and a monovalent anion; wherein the thiophenium cation has the following formula (I):

[0017]

[0018] in

[0019] R1=C1-C8 alkyl wherein at least one hydrogen atom of the C1-C8 alkyl is substituted by a halogen atom;

[0020] R2, R3, R4, R5, R6, R7, R8, R9 = hydrogen, C1-C8 alkyl, or C1-C8

[0021] The C1-C8 alkyl group wherein at least one hydrogen atom of the alkyl group is substituted by a halogen atom, or halogen.

[0022] Thus, in an unforeseeable manner, a new dental composition comprising an initiator system could be provided which does not exhibit the above-mentioned disadvantages of the known prior art dental compositions.

[0023] In particular, the present invention provides a dental composition comprising a free radical initiator system which should be at least substantially free of amines, preferably completely free of amines, in particular tertiary amines, more in particular aromatic tertiary amines.

[0024] Thus, the present invention provides novel co-initiators for common photosensitizers such as camphorquinone in dental compositions, wherein the co-initiators are free of amines.

[0025] Furthermore, a dental composition comprising a free radical initiator system is provided, which system contains a combination of a photosensitizer and at least one specific co-initiator, wherein the inventive dental composition can reduce or ideally avoid or eliminate the leaching problems and toxicological concerns of conventional co-initiators based on aromatic tertiary amines while at the same time improving the desired biocompatibility.

[0026] Dental compositions containing this specific inventive co-initiator provide improved polymerization efficiency, including good conversion, without causing leaching problems of aromatic amines. This specific inventive co-initiator of the present invention is stable to strongly acidic media and is therefore suitable for dental applications such as adhesives, composites, cements, and self-etching formulations. This type of co-initiator of the present invention has a low tendency to discolor when incorporated into such dental compositions, while at the same time exhibiting good storage stability.

[0027] At least one co-initiator functions by initiating polymerization of one or more polymerizable monomers having at least one ethylenically unsaturated group.The co-initiators of the present invention provide biocompatibility with reduced release of components when incorporated into such dental compositions. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] For a more complete understanding of the present invention, reference is made to the following detailed description considered in conjunction with the accompanying drawings, in which:

[0029] Figure 1 The photopolymerization curves of six different thiophenium salts as co-initiators in combination with CQ for the polymerization of Prime&bond Active resin (a methacrylate resin) are plotted compared to CQ in combination with a tertiary amine.

[0030] Figure 2 The photopolymerization curves of a specific thiophenonium salt (5) as a co-initiator in combination with CQ (both in several different amounts) for the polymerization of Prime & bond Active resin (a methacrylate resin) are plotted compared to CQ in combination with iodonium ion;

[0031] Figure 3 The photopolymerization curves of a specific thiophenonium salt (1) as a co-initiator in combination with CQ for polymerizing Prime & bond Active resin (a methacrylate resin) are plotted compared to CQ in combination with two thiophenonium alternatives. DETAILED DESCRIPTION

[0032] Unless otherwise specified, the term "alkyl" refers to a monovalent radical, branched or unbranched, saturated hydrocarbon chain having from 1 to 18 carbon atoms. This term can be exemplified by groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, neopentyl, n-hexyl, n-decyl, dodecyl, tetradecyl, and the like.

[0033] Unless otherwise specified, the term "alkoxy" refers to a monovalent group having 1 to 18 carbon atoms, a branched or unbranched saturated hydrocarbon chain, wherein at least one carbon atom of such alkoxy is substituted by an oxygen atom. Such alkoxy is attached to a carbon atom of the compound via the at least one oxygen atom. The term can be exemplified by groups such as methoxy, ethoxy, and the like. This means that the term "alkoxy" in the context of the present invention is defined as any chemist would understand based on common chemical knowledge.

[0034] Unless otherwise specified, the term "alkylene" refers to a straight-chain saturated divalent hydrocarbon group having one to four carbon atoms or a branched-chain saturated divalent hydrocarbon group having three to four carbon atoms, such as methylene, ethylene, 2,2-dimethylethylene, propylene, 2-methylpropylene, butylene and the like, preferably methylene, ethylene or propylene.

[0035] The term "aryl" refers to a C6-C10 membered aromatic, heterocyclic, fused aromatic, fused heterocyclic, diaromatic or diheterocyclic ring system. Broadly defined, "aryl" as used herein includes 5-, 6-, 7-, 8-, 9- and 10-membered monocyclic aromatic groups, which may include from zero to four heteroatoms, such as benzene, pyrrole, furan, thiophene, imidazole, oxazole, thiazole, triazole, pyrazole, pyridine, pyrazine, pyridazine, pyrimidine and the like. Those "aryl" groups having heteroatoms in the ring structure may also be referred to as "heteroaryls" or "heterocyclic compounds" or "heteroaromatic compounds." The aromatic ring may be substituted at one or more ring positions with one or more substituents including, but not limited to, halogen, azide, alkyl, aralkyl, alkenyl, alkynyl, cycloalkyl, hydroxy, alkoxy, amino (or quaternized amino), nitro, sulfhydryl, imino, amido, phosphonate, phosphinate, carbonyl, carboxyl, silyl, ether, alkylthio, sulfonyl, sulfonamido, ketone, aldehyde, ester, heterocyclyl, aromatic or heteroaromatic moiety, -CF3, -CN, and combinations thereof.

[0036] The term "cycloalkyl" refers to a monocyclic or polycyclic cycloalkyl group. Examples of monocyclic cycloalkyl groups include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, and cyclooctyl. Examples of polycyclic cycloalkyl groups include, for example, adamantyl, norbornyl, decalinyl, 7,7-dimethyl-bicyclo[2.2.1]heptanyl, tricyclo[5.2.1.02,6]decyl, and the like.

[0037] In the context of the present invention, the term "(meth)acrylate" is intended to refer to acrylates as well as to the corresponding methacrylates.

[0038] In the context of the present invention, the term "(meth)acrylamide" is intended to include acrylamide and methacrylamide.

[0039] In the context of the present invention, the term "polymerizable monomer" means any monomer capable of free radical polymerization. The polymerizable monomer includes at least one ethylenically unsaturated group. The at least one ethylenically unsaturated group includes vinyl, allyl, acryl, methacryl, and styryl.

[0040] The terms "polymerizable monomer having at least one ethylenically unsaturated group" and "ethylenically unsaturated monomer" are used interchangeably.

[0041] In the context of the present invention, the term "free radical initiator system" means any system comprising a sensitizer and at least one coinitiator, which when activated by heat or light and / or ambient redox conditions forms free radicals, thereby initiating polymerization of polymerizable monomers.

[0042] In the context of the present invention, the term "coinitiator" is intended to mean a compound which does not absorb substantially when exposed to UV radiation or visible light, but which forms free radicals together with the sensitizer used according to the invention.

[0043] In the context of the present invention, the term "sensitizer" can absorb radiation with a wavelength of 400 to 800 nm upon exposure, but cannot form free radicals on its own, i.e. without the addition of a coinitiator. The sensitizer used in the present invention must be able to interact with the coinitiator used in the present invention.

[0044] The present invention relates to a dental composition selected from the group consisting of dental adhesives, dental composites, dental sealants and dental cements.

[0045] The dental compositions of the present invention comprise one or more polymerizable monomers having at least one ethylenically unsaturated group.

[0046] The polymerizable monomer may be an acrylate, a methacrylate, an ethylenically unsaturated compound, a carboxyl-containing unsaturated monomer, a C2-8 hydroxyalkyl (meth)acrylate, a C1-24 alkyl or cycloalkyl (meth)acrylate, a C2-18 alkoxyalkyl (meth)acrylate, an olefin or diene compound, a monoester / diester, a monoether, an adduct, a vinyl monomer, a styrene-based monomer, a TPH resin, an SDR resin, a PBA resin, and / or a BPA-free resin.

[0047] Free radical initiator system

[0048] The dental compositions of the present invention include a free radical initiator system. The free radical initiator system may include a photoinitiator. Suitable photoinitiators may be present as binary or ternary systems. Binary systems may include a photosensitizer and a thiophenonium salt as a co-initiator. Ternary systems may also include an iodonium, sulfonium, or phosphonium salt.

[0049] In one embodiment, the monovalent anion of the thiophenium salt is selected from the group consisting of sulfonate, substituted sulfonate, borohydride, and substituted borohydride.

[0050] In a preferred embodiment thereof, the monovalent anion of the thiophenium salt is selected from the group consisting of alkylsulfonate, substituted alkylsulfonate, borohydride, and said substituted borohydride wherein at least one hydrogen atom of the borohydride is substituted with a halogen atom.

[0051] In an even more preferred embodiment, the monovalent anion of the thiophenium salt is selected from the group consisting of: an alkylsulfonate in which at least one hydrogen atom, preferably all hydrogen atoms, of the alkyl group are substituted by a halogen atom, and a borohydride in which all hydrogen atoms are substituted by a halogen atom.

[0052] In another preferred embodiment, the thiophenium cation has the following formula (II):

[0053]

[0054] in

[0055] R4, R7, R 10 、R 11 、R 12 = hydrogen, C1-C8 alkyl, C1-C8 alkyl wherein at least one hydrogen atom of the C1-C8 alkyl is replaced by a halogen atom, or halogen; provided that R 10 、R 11 、R 12 At least one of = the C1-C8 alkyl group in which at least one hydrogen atom is substituted by a halogen atom, or halogen.

[0056] In a more preferred embodiment thereof,

[0057] R4 and R7 = hydrogen or halogen, and R 10 、R 11 、R 12 =halogen.

[0058] In another preferred embodiment, the thiophenium cation has one of the following formulae (III) or (IV):

[0059]

[0060] In one embodiment, the thiophenium salt is present in an amount of 0.1 to 5 weight percent, preferably in an amount of 0.15 to 2.5 weight percent, and more preferably in an amount of 0.2 to 2 weight percent, based on the total weight of the dental composition.

[0061] Finally, according to one embodiment of the invention, the at least one coinitiator is a compound according to one of the formulae (I), (II), (III) or (IV) defined above.

[0062] In one embodiment, more than one coinitiator compound is comprised by the inventive free radical initiator system, wherein all comprised coinitiator compounds are compounds according to one of formula (I), (II), (III) or (IV).

[0063] In an alternative embodiment, more than one coinitiator compound is comprised by the inventive free radical initiator system, wherein each of the comprised coinitiator compounds is a compound according to one of formula (I), (II), (III) or (IV), and wherein at least two of these coinitiator compounds are compounds according to the above-mentioned formula (I), (II), (III) or (IV).

[0064] In another alternative embodiment, more than one coinitiator compound is comprised by the inventive free radical initiator system, wherein all comprised coinitiators are compounds according to formula (I), (II), (III) or (IV) above.

[0065] In one embodiment, the photosensitizer is a 1,2-diketone compound.

[0066] The α-diketone sensitizer compound may be selected from the group consisting of camphorquinone, 1,2-diphenylethane-1,2-dione (benzil), 1,2-cyclohexanedione, 2,3-pentanedione, 2,3-hexanedione, 3,4-hexanedione, 2,3-heptanedione, 3,4-heptanedione, glyoxal, butanedione, 3,3,6,6-tetramethylcyclohexanedione, 3,3,7,7-tetramethyl-1,2-cycloheptanedione, 3,3,8,8-tetramethyl-1,2-cyclooctanedione, 3,3,18,18-tetramethyl-1,2-cyclooctadecanedione, dipivaloyl, furil, hydroxybenzil, 2,3-butanedione, 2,3-octanedione, 4,5-octanedione, and 1-phenyl-1,2-propanedione.

[0067] In a preferred embodiment, the photosensitizer is camphorquinone (CQ).

[0068] In one embodiment, the photosensitizer is present in an amount of 0.1 to 5 wt%, preferably in an amount of 0.15 to 2.5 wt%, and more preferably in an amount of 0.2 to 2 wt%, based on the total weight of the dental composition.

[0069] In one embodiment, the ratio of the amount of photosensitizer to the amount of coinitiator is from 1:2.5 to 2.5:1, preferably from 1:3.5 to 3.5:1, and more preferably from 1:5 to 5:1.

[0070] In one embodiment, the free radical initiator system is present in an amount of 0.1 to 10 weight percent based on the total weight of the dental composition.

[0071] In one embodiment, the dental composition comprises a free radical initiator system that is at least substantially free of amines, preferably completely free of amines, especially tertiary amines, more especially aromatic tertiary amines.

[0072] In one embodiment, the dental composition further comprises an additive selected from iodonium salts, phosphonium salts and sulfonium salts, preferably wherein the additive is an iodonium salt.

[0073] In one preferred embodiment, the additive is present in an amount of 0.01 to 5 weight percent based on the total weight of the dental composition.

[0074] Such iodonium compounds may comprise the following formula (C):

[0075] R 21 -I + -R 22 A - Formula (C)

[0076] in

[0077] R 21 and R 22 Independently of each other, they represent organic structural parts, and

[0078] A - For anion.

[0079] In embodiments, the iodonium compounds include diphenyliodonium (DPI) hexafluorophosphate, di(4-methylphenyl)iodonium (Me2-DPI) hexafluorophosphate, di-(4-tert-butylphenyl)-iodonium hexafluorophosphate, diaryliodonium hexafluoroantimonate, (4-methylphenyl)[4-(2-methylpropyl)phenyl]iodonium hexafluoroantimonate, (4-methylphenyl)[4-(2-methylpropyl)phenyl]iodonium hexafluorophosphate ( 250, a commercial product available from BASF SE), (4-methylphenyl)[4-(2-methylpropyl)phenyl]iodonium tetrafluoroborate, 4-octyloxyphenylphenyliodonium hexafluoroantimonate, 4-(2-hydroxytetradecyloxyphenyl)phenyliodonium hexafluoroantimonate, and 4-isopropyl-4′-methyldiphenyliodonium borate.

[0080] According to another embodiment, the iodonium compound is bis-(4-tert-butylphenyl)-iodonium hexafluorophosphate (SC938), bis(4-methylphenyl)iodonium (Me2-DPI) hexafluorophosphate, or bis(4-tert-butylphenyl)iodonium p-toluenesulfonate.

[0081] According to yet further embodiments, the photoinitiator may include a sulfonium compound having the following formula (D):

[0082] R 23 R 24 R 25 S + A - Formula (D)

[0083] in

[0084] R 23 、R 24 and R 25 Independent of each other, represents an organic structural part; or wherein R 23 、R 24 and R 25 Any two of them together with the sulfur atoms to which they are bound form a ring structure, and

[0085] A - For anion.

[0086] The triarylsulfonium salt may be S-(phenyl)thianthrenium hexafluorophosphate:

[0087]

[0088] According to another embodiment, the photoinitiator may include a phosphonium compound having the following formula (E):

[0089] R 26 R 27 R 28 R 29 P + A - Formula (E)

[0090] in

[0091] R 26 、R 27 、R 28 and R 29 Independently of each other, they represent organic structural parts, and

[0092] A - For anion.

[0093] The phosphonium salt of formula (E) may be a tetraalkylphosphonium salt, tetrakis(hydroxymethyl)phosphonium (THP) salt or tetrakis(hydroxymethyl)phosphonium hydroxide (THPOH) salt, wherein the anion of the tetraalkylphosphonium salt is selected from the group consisting of formate, acetate, phosphate, sulfate, fluoride, chloride, bromide and iodide.

[0094] Other suitable photoinitiators for polymerizing free radical photopolymerizable compositions may include phosphine oxides, which generally have a functional wavelength range of about 380 nm to about 1200 nm. Other suitable phosphine oxide free radical initiators having a functional wavelength range of about 380 nm to about 450 nm are acyl and diacylphosphine oxides.

[0095] The present invention therefore solves the problem of providing an inventive dental composition comprising a revised initiator system.

[0096] The following non-limiting examples are provided to illustrate embodiments of the invention and to facilitate understanding of the invention, but are not intended to limit the scope of the invention as defined by the appended claims.

[0097] The following different thiophenium salts have been used in the invention and comparative experiments:

[0098]

[0099]

[0100] Example 1: Systematic study of all six different thiophenium salts shown above as co-initiators in combination with CQ for the polymerization of Prime&bond Active resin (a methacrylate resin) compared to CQ in combination with tertiary amines

[0101] Photopolymerization curve of C=C double bond (PrimeBond Active) in the presence of camphorquinone (CQ) as photoinitiator ( Figure 1 (shown in ) (in air, thickness 13 μm, SmartLite Focus 300 mW / cm 2 ):

[0102] (1) CQ / thiophenium 1 (1.5 / 1% w / w)

[0103] (2) CQ / thiophenium 2 (1.5 / 1% w / w)

[0104] (3) CQ / thiophenium 3 (1.5 / 1% w / w)

[0105] (4) CQ / thiophenium 4 (1.5 / 1% w / w)

[0106] (5) CQ / thiophenium 5 (1.5 / 1% w / w)

[0107] (6) CQ / thiophenium 6 (1.5 / 1% w / w) and

[0108] (7) CQ / ethyl 4-(dimethylamino)benzoate (EDB) (1.5 / 1% w / w).

[0109] Irradiation (LED at 477 nm) starts at t = 8 s (e.g. Figure 1 as depicted in ).

[0110] It is clearly shown here that the inventive effect is achieved only if the compound of formula (I) as claimed in claim 1 is chosen instead of EDB, meaning a photopolymerization conversion with at least similar prior art systems of well-established CQ and tertiary amines like EDB.

[0111] Good results were achieved for the inventive examples of thienyliums 1, 3, and 5; whereas comparative examples were produced using thienyliums 2, 4, and 6. Thienyliums 1, 3, and 5 have thus proven to offer a promising approach to replacing tertiary amines with certain specific thienylium compounds. However, as shown, even in this case, the applicants carefully investigated the possible candidates in order to investigate which thienylium compounds (salts) were suitable for this application and which were not.

[0112] Example 2: Systematic study of different amounts of thiophenonium salt 5 (shown above) as a co-initiator in combination with different amounts of CQ for polymerization of Prime&bond Active resin (a methacrylate resin) compared to CQ in combination with an iodonium compound (SC938)

[0113] Photopolymerization curve of C=C double bond (PrimeBond Active) in the presence of camphorquinone (CQ) as photoinitiator ( Figure 2 (shown in ) (in air, thickness 13 μm, SmartLite Focus 300 mW / cm 2 ):

[0114] (1) CQ / thiophenium 5 (1.5 / 1.5% w / w)

[0115] (2) CQ / thiophenium 5 (1.5 / 1% w / w)

[0116] (3) CQ / thiophenium 5 (1.5 / 0.5% w / w)

[0117] (4) CQ / thiophenium 5 (1 / 1.5% w / w)

[0118] (5) CQ / thiophenium 5 (1 / 0.5% w / w) and

[0119] (6) CQ / SC938 (1 / 0.5% w / w).

[0120] Irradiation (LED at 477 nm) was started again from t = 8 s (as Figure 1 as depicted in ).

[0121] It is clearly demonstrated here that the inventive initiator system based on the combination of CQ with a selective thiophenium compound according to the claims, in this example thiophenium 5, provides better photopolymerization conversion results than initiator systems based on the well-established prior art systems of CQ and iodonium compounds.

[0122] Furthermore, some different ratios of the amount of CQ and the corresponding thiophenium 5 were investigated. Figure 2 It follows that all photopolymerization results are promising, even if the results differ more or less from each other when depending on the exact ratios.

[0123] Good solubility was shown for all initiator systems used in Example 2. Excessive amounts of initiator generally limit their possible use due to severe solubility problems.

[0124] These initiator systems have subsequently been successfully used to provide transparent dental adhesives that do not produce a yellow adhesive layer after curing (caused by unreacted photoinitiators such as CQ) and at the same time do not result in a significant loss of polymerization efficiency.

[0125] Thus, the inventive initiator system also exhibits unusual bleaching properties after irradiation with a blue dental LED, as shown in Table 1.

[0126] Table 1: Optical examination of the dental adhesive of Example 2

[0127] Figure 2 Curve number L value A value B value 1 66.69 -3.13 4.93 2 66.78 -3.28 5.38 3 66.70 -3.20 4.95 4 66.68 -3.14 4.89 5 66.69 -3.13 4.93 6 (Prior Art) 66.73 -3.19 4.92

[0128] Photographs of the samples were taken before and after polymerization. Based on these photographs, L, a, and b values ​​were measured for each sample after irradiation. The corresponding polymerizations were performed in air with a SmartLite Focus 300 mW / cm 2 , in the monomer Prime&Bond Active, irradiation started from t=5s to t=120s, with a thickness of 13μm.

[0129] Example 3: Preparation and analysis of different dental adhesive compositions using different thiophenium salts as co-initiators in combination with different amounts of CQ compared to CQ in combination with a tertiary amine (DMABN)

[0130] All components were weighed into a brown glass slide and stirred at room temperature for 24 hours.The solution was filtered using a 0.45 μm PTFE filter.

[0131] The shear bond strength (SBS) of each example was measured according to ISO 29022 with a sample size of 7 instead of 15. Table 2 below shows the results of Experiments 3a to 3i, where all experiments are inventive examples except Examples 3b and 3f which are comparative examples.

[0132] Table 2: Experiments 3a to 3i including SBS analysis data

[0133]

[0134] Example 4: Systematic study of alternatives to thiophenium 1 as co-initiators in combination with CQ for polymerization of Prime & bond Active resin (a methacrylate resin) compared to CQ in combination with tertiary amines

[0135] The following two alternatives were investigated for comparison with thiophenium salts as co-initiators:

[0136]

[0137] Photopolymerization curve of C=C double bond (PrimeBond Active) in the presence of camphorquinone (CQ) as photoinitiator ( Figure 3 (shown in ) (in air, thickness 13 μm, SmartLite Focus 300 mW / cm 2 ):

[0138] (1) CQ / thiophenium 1 (1.5 / 1% w / w)

[0139] (2) CQ / thianthrenium (1.5 / 1% w / w)

[0140] (3) CQ / matte (1.5 / 1% w / w) and

[0141] (4) CQ / ethyl 4-(dimethylamino)benzoate (EDB) (1.5 / 1% w / w).

[0142] Irradiation (LED at 477 nm) starts at t = 8 s (e.g. Figure 1 as depicted in ).

[0143] Table 3: Optical examination of the dental adhesive of Example 4

[0144] Figure 3 Curve number L value A value B value 1 (Example of the Invention) 66.96 -3.70 5.70 2 (Comparative Example) 66.79 -3.60 5.30 3 (Comparative Example) 66.77 -3.60 5.10 4 (Existing Technology) 66.88 -3.70 6.20

[0145] Photographs of the samples were taken before and after polymerization. Based on these photographs, L, a, and b values ​​were measured for each sample after irradiation. The corresponding polymerizations were performed in air with a SmartLite Focus 300 mW / cm 2, in the monomer Prime&Bond Active, irradiation started from t=5s to t=120s, with a thickness of 13μm.

[0146] As can be seen from the comparative photopolymerization conversion results, the planned alternatives to the thiophenium compounds as claimed, ie, thianthrenium or sulfonium salts, did not provide sufficient experimental conversion percentages for photopolymerization, even though their optical values ​​as subsequently determined were good enough to provide clear dental adhesives.

[0147] Thus, even these chemically very similar compounds do not provide properties as good as those of the selected thiophenium compounds as desired.

[0148] This demonstrates that both the selection of the exact thiophenium compound itself and the selection of the chemical properties of such compounds are relevant to achieving the technical teachings of the present invention.

[0149] Although the principles of the present invention have been described with respect to certain embodiments, it is to be understood that various modifications thereof will become apparent to those skilled in the art upon reading the specification. Therefore, it is to be understood that the invention disclosed herein is intended to encompass such modifications as fall within the scope of the appended claims. The scope of the present invention is limited solely by the scope of the appended claims.

Claims

1. A dental composition comprising: a) at least one polymerizable monomer having at least one ethylenically unsaturated group; and b) a free radical initiator system comprising: i. a photosensitizer comprising camphorquinone; and ii. a co-initiator compound; It is characterized by: The coinitiator compound is a thiophenium salt composed of a thiophenium cation and a monovalent anion; wherein the thiophenium cation has the following formula (II): (II) in R4, R7, R 10 、R 11 、R 12 = hydrogen or halogen, provided that R 10 、R 11 、R 12 At least one of = halogen.

2. The dental composition according to claim 1, characterized in that The monovalent anion of the thiophenium salt is selected from the group consisting of sulfonate, substituted sulfonate, borohydride, and substituted borohydride.

3. The dental composition according to claim 2, characterized in that The monovalent anion of the thiophenium salt is selected from the group consisting of an alkylsulfonate, a substituted alkylsulfonate, a borohydride, and a substituted borohydride in which at least one hydrogen atom of the borohydride is substituted with a halogen atom.

4. The dental composition according to claim 3, characterized in that The monovalent anion of the thiophenium salt is selected from the group consisting of substituted alkylsulfonates in which at least one hydrogen atom of the alkyl group of alkylsulfonates is substituted with a halogen atom, and substituted borohydrides in which all hydrogen atoms of borohydrides are substituted with halogen atoms.

5. The dental composition according to claim 3, characterized in that The monovalent anion of the thiophenium salt is selected from the group consisting of substituted alkylsulfonates in which all hydrogen atoms of the alkyl group of the alkylsulfonate are substituted with halogen atoms, and substituted borohydrides in which all hydrogen atoms of the borohydride are substituted with halogen atoms.

6. The dental composition according to claim 1, characterized in that R4 and R7 = hydrogen or halogen, and R 10 、R 11 、R 12 =Halogen.

7. The dental composition according to any one of claims 1 to 6, characterized in that The thiophenium cation has one of the following formulas (III) or (IV): (III) (IV).

8. The dental composition according to any one of claims 1 to 6, characterized in that The thiophenium salt is present in an amount of 0.1 to 5 weight percent based on the total weight of the dental composition.

9. The dental composition according to any one of claims 1 to 6, characterized in that The thiophenium salt is present in an amount of 0.15 to 2.5 weight percent based on the total weight of the dental composition.

10. The dental composition according to any one of claims 1 to 6, characterized in that The thiophenium salt is present in an amount of 0.2 to 2 weight percent based on the total weight of the dental composition.

11. The dental composition according to any one of claims 1 to 6, characterized in that The photosensitizer is present in an amount of 0.1 to 5 weight percent based on the total weight of the dental composition.

12. The dental composition according to any one of claims 1 to 6, characterized in that The photosensitizer is present in an amount of 0.15 to 2.5 weight percent based on the total weight of the dental composition.

13. The dental composition according to any one of claims 1 to 6, characterized in that The photosensitizer is present in an amount of 0.2 to 2 weight percent based on the total weight of the dental composition.

14. The dental composition according to any one of claims 1 to 6, characterized in that The ratio of the amount of the photosensitizer to the amount of the co-initiator is 1:2.5 to 2.5:

1.

15. The dental composition according to any one of claims 1 to 6, characterized in that The ratio of the amount of the photosensitizer to the amount of the co-initiator is 1:3.5 to 3.5:

1.

16. The dental composition according to any one of claims 1 to 6, characterized in that The ratio of the amount of the photosensitizer to the amount of the co-initiator is 1:5 to 5:

1.

17. The dental composition according to any one of claims 1 to 6, characterized in that The dental composition further comprises an additive selected from the group consisting of iodonium salts, phosphonium salts, and sulfonium salts.

18. The dental composition according to claim 17, characterized in that The additive is iodonium salt.

19. The dental composition according to claim 17, characterized in that The additive is present in an amount of 0.01 to 5 wt % based on the total weight of the dental composition.

20. The dental composition according to any one of claims 1 to 6, characterized in that The free radical initiator system is present in an amount of 0.1 to 10 weight percent, based on the total weight of the dental composition.

21. The dental composition according to any one of claims 1 to 6, characterized in that The dental composition comprises a free radical initiator system that is at least substantially free of amines.

22. The dental composition according to claim 21, characterized in that The dental composition comprises a free radical initiator system that is completely free of amines.

23. The dental composition according to claim 21, characterized in that The amine is a tertiary amine.

24. The dental composition according to claim 21, characterized in that The amine is a tertiary aromatic amine.

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