DE19937093A1 - Adhesive system comprising a cationic- and radical initiator and cationically/radically polymerizable component is useful for bonding radically and/or cationically curable materials to teeth - Google Patents

Abstract

The use of an adhesive system (I), comprising: (A) a cationic initiator and a radical initiator; and (B) a cationically and radically polymerizable component, for the bonding of radically and/or cationically curable materials onto water-containing hard tissue, is claimed.

Description

The present invention relates to adhesive systems based on cationic and radical curing compounds and their use.

To date, methacrylate and acrylate monomers have predominantly been used in polymerizable dental materials. The 2,2-bis- [4- (2-hydroxy-3-methacryloyloxypropoxy) phenyl] propane (bis-GMA) described by Bowen deserves special attention [US-A-3 066 112]. Mixtures of this methacrylate with triethylene glycol dimethacrylate are still used today as the standard formulation for dental plastic direct filling materials. Methacrylic derivatives of the double-formylated bis- (hydroxymethyl) tricyclo [5.2.1.0 ^2,6 ] decane have also proven themselves as monomers for dental composites [W. Gruber et al., DE-A-27 14 538; W. Schmitt et al., DE-A-28 16 823; J. Reiners et al., EP-A-0 261 520]. A major disadvantage of these dental materials is the high volume shrinkage caused by the polymerization. This can be minimized, for example, by using ring-opening monomers, such as the cationically curing epoxides.

There is little about cationically curable epoxy materials for dental applications known: The patent US-A-5 556 896 describes epoxy-containing compositions which necessarily as shrinkage compensating monomers spiroorthocarbonates must contain. Bowen describes a mass containing quartz sand and a aliphatic diepoxide (bisphenol A diglycidyl ether), which in the hardened Condition supposedly shows good stability in the oral environment [J. Dent. Res. 35, 1956, 360-379]. The company Ciba describes in the patent AT-A-204 687 epoxy dental compositions based on bisphenol-A, which is cured using Lewis acid catalysts become. The documents DE-A-196 48 283, WO / 96/3538 and WO / 95/30402 also describe polymerizable dental compositions based on epoxides and their use.

Although there is extensive experience with epoxides and cycloaliphatic Epoxides there (U.S.-A-2,716,123, U.S.-A-2,750,395, U.S.-A-2,863,881, U.S.-A-3,187 018), are such monomers and cationically polymerizable formulated therefrom No masses with the properties necessary for dental applications The time was commercially available. The reason for this is probably also that  so far no adhesive systems for fixing cationically curing Dental materials on hard tissue there.

For fastening dental filling materials based on (meth) acrylate - that is radical curing systems - so-called adhesive systems are used, which in complicated application must be used accurately. Become the - from system to system very different - instructions for use of the If the manufacturer is not followed exactly, the result is a very poor quality Composite that the permanent survival of the entire restoration and especially endangered of the tooth.

The quality of these adhesive systems is reflected in the following criteria:

• - Complete adherence to the hard tooth substance without defects ("Sealing");
• - full adhesion to the filling material,
• - Lasting bond.

One cannot assume that a cationically cross-linking material a radically curing adhesive system one for dental use can show sufficient adhesion, since the respective crosslinking reactions chemically and physically (for example kinetically) perfectly run differently.  

WO / 98/470 46 describes photopolymerizable mixtures based on epoxy, containing an epoxy resin, an iodonium salt, a sensitive in visible light Transfer molecule and an electron donor and claims their Use as a dental adhesive system. However, it has been shown that with such mixtures on the tooth structure no adhesion to cationic and / or radical-curing mixtures can be achieved (see Comparative Mixtures 1-3 of this document).

At no time is an adhesive system commercially available on the market been the one for use in attaching cationic and / or radically curing materials is indicated on the hard tooth substance.

The object of the present invention is to provide adhesive systems places that are capable of cationically and / or radically crosslinking materials Hard tissue containing water, such as tooth, for adhesion bring.

According to the invention, this object is achieved by using Adhesive systems containing at least one component i) at least one system capable of initiating cationic polymerization, and a system capable of initiating radical polymerization, and at least one component ii) which is cationically and free-radically polymerizable.

Quite surprisingly, it has been found and is shown here that when added of cationically curing connecting parts in radical adhesive systems  Adhesion to purely radical curing materials does not deteriorate, but even improved beyond the known level. It was just as surprising found and shown here that when using the above Adhesive systems for cationic curing materials, also a very good one Liability results.

A "hybrid mixture" is thus formed in the adhesives according to the invention cationic and radical networks that stand up for all liability mentioned materials - and of course also for "hybrid materials" cationic and radical curing systems - very suitable. On Another effect of these systems that promotes liability is the training of known to arise in free-radically crosslinking systems "Smear layer". This comes about through the oxygen inhibition and ensures optimal mixing in the interface between adhesive and. Dental material.

A major advantage of the invention is on the one hand for the practical worker Dentist that with just one system with all different curing Materials can work, and on the other hand only one possibility for use of these materials is created.

The invention is described in more detail below.

The adhesive mixes, which have the advantages described have use according to the invention, contain as component i)  preferably 0.01 to 94.90% by weight, in particular 0.1 to 90% by weight and particularly preferably 0.1 to 80% by weight of an initiator system which is capable of start cationic polymerization and 0.01 to 5 wt .-%, in particular 0.1 up to 4% by weight and particularly preferably 0.1 to 3% by weight of an initiator system, that is capable of initiating radical polymerization, and as component ii) preferably 0.1 to 94.99% by weight, in particular 0.5 to 95.90 % By weight and particularly preferably 1 to 96.90% by weight of a cationic and radically polymerizable material.

The following cationic initiators come into consideration in component i):

• - Unsaturated carboxylic acids, ie mono- or polyunsaturated organic mono-, di- or polycarboxylic acids, or their precursors, which can form acids with water, such as. B. anhydrides or acid chlorides, especially acidic methacrylic acid esters or amides.
  Unsaturated carboxylic acids of the following formula are preferred:
  in which mean:
  R ¹ , R ² , R ³ = H, C ₁ - to C ₂₅ - alkyl or cycloalkyl radicals, optionally substituted or bridged with N, O, S, Si, P or halogen, or aromatic C ₆ to C ₁₂ - Residues or heterocyclic C ₃ to C ₁₂ residues with N, O, S, P and optionally substituted with halogen.
  Acids such as 4-methacryloxyethyltrimellitic acid or its anhydrides (Takeyama, M, et al., J. Jap. Soc. F. Dent. App. A. Mat. 19, 179 (1978)) or the reaction products of trimelitic acid chloride anhydride can also be used aminic, thiolic or hydroxylic (meth) acrylic acid esters, such as 2-hydroxyethylene methacrylate or methacroyloxy-ethyl-o-phthalate.
• - Unsaturated phosphoric and phosphonic acids.
  Z are preferred. B. unsaturated organic esters of monofluorophosphonic acids, as described for example in US Pat. No. 3,997,504, unsaturated organic esters of acids of phosphorus which contain chlorine or bromine bonded directly to the phosphorus, as described, for example, in EP-A 0 058 483 are described, unsaturated organic esters of phosphoric acid, which are present as cyclic pyrophosphates (anhydrides), as described, for example, in DE-A-30 48 410, and unsaturated organic esters of phosphoric or phosphonic acids, as described, for example, in DE-A-27 71 234 and DE-A-31 50 285 are described. The hydrolysis-stable, polymerizable acrylic phosphonic acids of DE-A-197 46 708 are equally preferred.
• Suitable monomers containing phosphoric acid groups are furthermore described, for example, in US Pat. Nos. 4,282,035, 4,222,780, 4,235,633, 4,359,117 and 4,368,043 and in EP-A-0 084 407. Ethylene-unsaturated phosphoric acid esters or phosphoric acid esters according to the following formula are preferably used in the adhesive mixtures according to the invention:
  in which mean:
  X = O, S,
  R ⁴ and R ⁵ independently of one another are H, OH or C ₁ - to C ₂₅ -alkyl or -cycloalkyl radicals, optionally substituted or bridged with N, O, S, Si, P or halogen, or aromatic C ₆ to C ₁₂ - Residues or heterocyclic C ₃ to C ₁₂ residues with N, O, S, P and optionally substituted with halogen, or substituted with acrylic acid esters, or a residue of the formula
  wherein R ^{6 is} hydrogen or C ₁ - to C ₆ -alkyl and n is an integer ≧ 1, and
  A is a divalent C ₁ to C ₂₅ alkyl or cycloalkyl radical, optionally substituted or bridged with N, O, S, Si, P or halogen, or aromatic C ₆ to C ₁₂ radicals or heterocyclic C ₃ to C ₁₂ Radicals with N, O, S, P and optionally substituted with halogen,
  with the proviso that the radical containing R ⁶ is present at least once.
• - Substituted, unsaturated sulfonic acids and their esters.
• - Inorganic acids such as mineral acids, super acids such as HSbF ₆ or HBF ₄ , Lewis acids such as BF ₃ adducts, metal salts such as FeCl ₃ , ZnCl ₂ , or complex acids or precursors of acids such as acid chlorides or anhydrides.
• - Cationic photopolymerization initiators, such as those in the WO / 98/47046 or in DE-A-197 36 471 and DE-A-197 43 564 are.

The aforementioned cationic initiator systems can be used alone or in Mixtures are used, the enumerations being exemplary and in none Way to be understood finally.

Molecules which carry canonically curable and one or more unsaturated groups are used as component ii) in the adhesive systems according to the invention. These compounds can correspond, for example, to the following structural formula, the epoxidic group also being able to be replaced by one or more other cationically polymerizable groups, as described, for example, below (p. 10):

in which mean:
n, m = integers ≧ 1,
R ⁷ = hydrogen or C ₁ to C ₈ alkyl or cycloalkyl,
R ^8,9,10 = H, C ₁ -C ₈ alkyl or cycloalkyl, where R ₅ and R ₆ can be covalently linked to one another,
A is a divalent C ₁ to C ₂₅ alkyl or cycloalkyl radical, optionally substituted or bridged with N, O, S, Si, P or halogen, or aromatic C ₆ to C ₁₂ radicals or heterocyclic C ₃ to C ₁₂ Residues with N, O, S, P and optionally substituted with halogen, or mixtures of said groups, it being possible for the epoxidic group to be replaced by one or more other cationically polymerizable groups.

In addition, cationically curable compounds may optionally be used can be added, which are selected from the following groups. Here is the List to be understood as an example and not to be understood as exhaustive.

• - Epoxy resins, as described for example in DE-A-196 48 283 A1 are, in particular 1,3,5,7-tetrakis (2,1-ethanediyl-3,4-epoxycyclohexyl) -1,3,5,7- tetramethylcyclotetrasiloxane.
• - Spiro-ortho-carbonates, such as 3,9-diethyl-3,9-dipropionyloxymethyl 1,5,7,11-tetraoxaspiro [5.5] undecane, 2,8-dimethyl-1,5,7,11-tetraoxaspiro [5.5] undecane, or 5,5-diethyl-19-oxadispiro [1,3-dioxane-2-2'-1,3-doixane-5 ', 4 "- bicyclo [4.1.0] heptane, or as described, for example, in US Pat. No. 5,556,896 are described, or spiro-orthoesters, or oxetanes, as described, for example, in  DE-A-197 36 471 p. 3f. or vinyl ethers, such as Alkyl or cycloalkyl vinyl ether, ethylene glycol divinyl ether, Triethylene glycol divinyl ether, glycidyl vinyl ether or butanediol vinyl ether.

The aforementioned materials can be used alone or in mixtures be used.

Radically curing compounds can also be added. Typical monomers or prepolymers which harden according to the radical chain mechanism and which may be present in component ii) are acrylates or methacrylates. Are suitable for. B. generally mono- and polyfunctional (meth) acrylate monomers. Typical representatives of this class of compounds (DE-A-43 28 960) are alkyl (meth) acrylates, including cycloalkyl (meth) acrylates, aralkyl (meth) acrylates and 2-hydroxyalkyl (meth) acrylates, for example hydroxypropyl methacrylate, hydroxyethyl methacrylate, isobornyl acrylate , Isobornyl methacrylate, butyl glycol methacrylate, acetyl glycol methacrylate, triethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, 2-phenylethyl methacrylate, 2-ethylhexyl methacrylate, cyclohexyl methacrylate, lauryl methacrylate and hexanediol di (meth) acrylate. The long-chain monomers of US Pat. No. 3,066,112 based on bisphenol A and glycidyl methacrylate or their derivatives formed by addition of isocyanates can also be used. Compounds of the bisphenyl-A-diethyloxy (meth) acrylate and bisphenol-A-dipropyloxy (meth) acrylate type are also suitable. The oligoethoxylated and oligopropoxylated bisphenol A diacrylic and dimethacrylic acid esters can also be used. Also suitable are the diacryl and dimethacrylic acid esters of bis (hydroxymethyl) tricyclo [5.2.1.0 ^2,6 ] decane and the diacryl and dimethacrylic acid esters of 1 to 3 ethylene oxide and / or propylene oxide units extended compounds of bis (hydroxymethyl) tricyclo [5.2.1.0 ^2,6 ] decane. Mixtures of the monomers mentioned can also be used.

The free radical initiators contained in component i) are described in the literature (e.g. J.-P Fouassier, Photoinitiation, Photopolymerization and Photocuring, Hanser Publishers, Munich, Vienna, New York, 1995 or J.-P Fouassier, J.F. Rabek (ed.), Radiation Curing in Polymer Science and Technology, Vol. II, Elsevier Apllied Science, London, New York, 1993). They can be substances that can be activated by UV or visible light be such as benzoin alkyl ethers, benzil ketals, acylphosphine oxides or aliphatic and aromatic 1,2-diketone compounds, for example Camphorquinone, the catalyst activity by adding activators, such as tertiary amines or organic phosphites, in a manner known per se can be accelerated.

Suitable initiator systems for triggering the radical polymerization via the peroxide / amine systems are a redox mechanism, Peroxide / barbituric acid derivatives or peroxide / acids u. The like. When using such initiator systems it is useful to have one initiator (e.g. peroxide) and one Keep the catalyst component (e.g. amine) separately. The two Components then become homogeneous with one another shortly before they are used mixed.  

The adhesive systems according to the invention can also contain fillers, dyes, Flow modifiers, stabilizers, solvents, ion-donating substances, bactericidal or antibiotic substances which increase the radiopacity Contain connections or other modifiers.

Preferred diluents are solvents such as dialkyl ketones (e.g. Acetone, methyl ethyl ketone), acetylacetone or alcohols (e.g. ethanol, propanol) or also thin-flowing polymerizable substances such as 2- Hydroxyethyl methacrylate or (2,3-epoxypropyl) methacrylate.

Suitable fillers are, for example, substances such as those used in conventional applications Dental materials are used, particularly preferably quartz, aerosils, highly disperse silicas, organic fillers or glass or mixtures these substances or also those as described in DE-A-196 48 283 A1 (page 10, line 48-59) are described.

Preferred ion-donating substances are those which enable the release of fluoride ions, for example fluoride salts of the first or second main group, such as, for example, As sodium fluoride or calcium fluoride, or complex fluoride salts, such as. B. KZnF ₃ , or as described in EP-A-0 717 977, fluoride-releasing glasses, and mixtures of these fluoride ion sources.

In addition, non-polymerizable acids can also be present, preferably a carboxylic acid, phosphoric acid, phosphonic acid, sulfuric acid, Sulfinic acid, sulfenic acid, mineral acid, Lewis acid or complex acid.

As bactericidal or antibiotic substances, for example Chlorhexidine, pyridine salts or the usual pharmaceutical substances, such as, for example, β-lactam antibiotics (penicillins), cephalosporins, tetracyclines, Ansamycine, Kanamycine, Chloramphenicol, Fosfomycin, antibacterial Macrolides, polypeptide antibiotics, chemotherapeutics, such as sulfonamides, in particular taurolidine, dihydrofolate reductase inhibitors, nitrofuran derivatives or gyrase inhibitors can be used. These can also be functionalized this way be integrated into the matrix, for example 12-methacrolyoloxydecylpiridinium bromide.

Contain the adhesive mixtures beyond components i) and ii) Additives, they can be used in amounts of 0.1% to 90% by weight be present individually or as a mixture, the mixture being prepared in such a way that they combine with components i) and ii) to a total of 100% by weight complete.

The invention is described in more detail below with the aid of examples these are to be understood as exemplary embodiments and are in no way limiting.

Adhesion measurement on cattle teeth using adhesive fixings Filling material

The adhesion network was checked by attempting a detention attempt Bovine teeth. 5 freshly extracted bovine teeth were used per experiment Sand the sanding paper so far that there is a sufficiently large exposed one Dentin surface was created. Wax plates were placed on each of these surfaces a punched hole of 6 mm glued to a standardized adhesive surface to obtain. Then the test area was based on the practice Procedure using a conventional phosphoric acid solution (Etitgel Minitip®, ESPE Dental AG, Seefeld) etched for 20 seconds and then with water rinsed off. On the dentin surfaces prepared in this way, one was completely Wetting the test surface with a sufficient amount of test mixtures incorporated into a microbrush for 20 seconds, briefly blown with compressed air and using a light polymerization device (Elipar Highlight®, from ESPE) for 20 Polymerized for seconds. The filling material was then in the Cut-outs in the wax platelets were made and exposed for 40 seconds polymerized. The wax plate was removed and the test specimen at 24 h Stored at 36 ° C and 100% humidity. Then the test specimens were placed in one Pull test (Zwick universal testing machine) deducted.

The adhesion values determined are shown in Table 1.

Production of a cationically curing filling material

The following ingredients are kneaded into a homogeneous paste in a three-finger kneader. For 100 g paste:

• - 75,000% by weight (75,000 g) quartz (average grain size 0.9 µm, was % By weight glycidyloxypropyltrimethoxysilane silanized);
• 0.525% by weight (0.525 g) of 4-methylphenyl-4-isopropylphenyl-iodonium tetrakis (penta-fluorophenyl) borate;
• 0.223% by weight (0.223 g) camphorquinone (Merck, Darmstadt);
• 0.001% by weight (0.001 g) of ethyl 4-dimethylaminobenzoate (from Merck, Darmstadt);
• - 0.001% by weight (0.001 g) 2-butoxyethyl 4-dimethylaminobenzoate;
• - 12.125% by weight (12.125 g) 3,4-epoxycyclohexyl-3,4- epoxycyclohexane carboxylate;
• - 12.125% by weight (12.125 g) 1,3,5,7-tetrakis (2,1-ethanediyl-3,4- epoxycyclohexyl) -1,3,5,7-tetramethylcyclotetrasiloxane.

Preparation of the adhesive mixture 1 according to the invention

To produce 10 g of adhesive mixture 1, the following constituents are mixed intensively:

• - 39.768% by weight (3.977 g) 10-methacryloyloxydecyl phosphate;
• - 24.315% by weight (2.431 g) 2-hydroxyethyl methacrylate;
• 1,200% by weight (0.120 g) camphorquinone (Merck, Darmstadt);
• 0.445% by weight (0.045 g) of ethyl 4-dimethylaminobenzoate (from Merck, Darmstadt);
• - 34.272% by weight (3.427 g) of 3,4-epoxycyclohexyl-3-hydroxy-4- methacrololyoxycyclohexane carboxylate;

Preparation of the adhesive mixture 2 according to the invention

The following constituents are mixed intensively with one another to produce 10 g of adhesive mixture 2:

• - 49.436% by weight (4.944 g) 10-methacryloyloxyethyl phosphate;
• - 14.884% by weight (1.488 g) 2-hydroxyethyl methacrylate;
• 0.594% by weight (0.059 g) camphorquinone (Merck, Darmstadt);
• 0.450% by weight (0.045 g) of ethyl 4-dimethylaminobenzoate (from Merck, Darmstadt);
• - 34.636% by weight (3.464 g) UVACURE 1561 (UCB, Drugsbos, Belgium)

Preparation of the comparison mixture 1

The following constituents are mixed intensively to produce 10 g of comparative mixture 1:

• 97.300% by weight (9.730 g) 1,3,5,7-tetrakis (2,1-ethanediyl-3,4-epoxycyclohexyl) 1,3,5,7-tetramethylcyclotetrasiloxane;
• - 2,000% by weight (0.200 g) Rhodorsil PI 2074 (Rhone Poulenc, iodonium salt);
• 0.500% by weight (0.050 g) camphorquinone (Merck, Darmstadt);
• - 0.200% by weight (0.020 g) BEDB (Lambson);

Preparation of the comparison mixture 2

The following constituents are mixed intensively with one another to produce 10 g of comparative mixture 2:

• 97.300% by weight (9.730 g) of 3,4-epoxycyclohexylmethyl-3,4- epoxycyclohexane carboxylate;
• - 2,000% by weight (0.200 g) Rhodorsil PI 2074 (Rhone Poulenc, iodonium salt);
• 0.500% by weight (0.050 g) camphorquinone (Merck, Darmstadt);
• - 0.200% by weight (0.020 g) BEDB (Lambson);

Preparation of the comparison mixture 3

The following constituents are mixed intensively with one another to produce 10 g of comparative mixture 3:

• - 48.650% by weight (4.865 g) 3,4-epoxycyclohexylmethyl-3,4- epoxycyclohexane carboxylate;
• 48.650% by weight (4.865 g) 1,3,5,7-tetrakis (2,1-ethanediyl-3,4-epoxycyclohexyl) 1,3,5,7-tetramethylcyclotetrasiloxane;
• - 2,000% by weight (0.200 g) Rhodorsil PI 2074 (Rhone Poulenc, iodonium salt);
• 0.500% by weight (0.050 g) camphorquinone (Merck, Darmstadt);
• - 0.200% by weight (0.020 g) BEDB (Lambson);

Table 1

Adhesion of the adhesive mixtures described in the examples

Claims (10)

1. Use of adhesive systems containing at least one Component i), comprising at least one system that is capable of one start cationic polymerization, and a system that is capable of a radical polymerization to start, and at least one component ii) which is cationically and radically polymerizable, for the attachment of radical and / or cationic hardening materials on water containing hard tissue. 2. Use according to claim 1, characterized in that component i) contains 0.01 to 94.90% by weight of an initiator system, that is able to start a cationic polymerization and 0.01 to 5 Wt .-%, contains an initiator system that is capable of a radical Start polymerization, and component ii) 0.1 to 94.99 wt .-% contains a cationically and radically polymerizable material. 3. Use according to one of claims 1 or 2, characterized in that that the materials are dental materials and the hard tissue is tooth. 4. Use according to claims 1 to 3, characterized in that component ii) contains compounds of the following formula:
in which mean:
n, m = integers ≧ 1,
R ⁷ = H, C ₁ -C ₈ alkyl or cycloalkyl, R ^8,9,10 = H, Me, C ₁ -C ₈ alkyl or cycloalkyl, where R ₅ and R ₆ can be covalently linked to one another,
A is a divalent C ₁ to C ₂₅ alkyl or cycloalkyl radical, optionally substituted or bridged with N, O, S, Si, P or halogen, or aromatic C ₆ to C ₁₂ radicals or heterocyclic C ₃ to C ₁₂ Radicals with N, O, S, P and optionally substituted with halogen, or mixtures of said groups, it being possible for the epoxidic group to be replaced by one or more other cationically polymerizable groups. 5. Use according to one of claims 1 to 4, characterized in that the following components are optionally additionally contained:

• a) a further radical and / or cationic photopolymerization initiator or mixtures thereof,
• b) a thinner,
• c) a filler,
• d) a source of fluoride ions,
• e) an acid which does not contain a double bond,
• f) a bactericidal or antibiotic agent.

6. Use according to one of claims 1 to 5, characterized in that component i) is selected from:

• 1. unsaturated carboxylic acids of the formula:
  in which mean:
  R ¹ , R ² , R ³ = H, C ₁ to C ₂₅ alkyl or cycloalkyl radicals, optionally substituted or bridged with N, O, S, Si, P or halogen, or aromatic C ₆ to C ₁₂ - Residues or heterocyclic C ₃ to C ₁₂ residues with N, O, S, P and optionally substituted with halogen,
  • - Ethylenically unsaturated phosphoric acid esters or phosphonic acid esters of the formula:
    
  in which mean:
  X = O, S,
  R ⁴ and R ⁵ independently of one another are H, OH or C ₁ - to C ₂₅ -alkyl or -cycloalkyl radicals, optionally substituted or bridged with N, O, S, Si, P or halogen, or aromatic C ₆ to C ₁₂ - Residues or heterocyclic C ₃ to C ₁₂ residues with N, O, S, P and optionally substituted with halogen, or substituted with acrylic acid esters, or a residue of the formula
  wherein R ^{6 is} hydrogen or C ₁ - to C ₆ -alkyl and n is an integer ≧ 1,
  A is a divalent C ₁ to C ₂₅ alkyl or cycloalkyl radical, optionally substituted or bridged with N, O, S, Si, P or halogen, or aromatic C ₆ to C ₁₂ radicals or heterocyclic C ₃ to C ₁₂ Radicals with N, O, S, P and optionally substituted with halogen,
  with the proviso that the radical containing R ⁶ is present at least once.

7. Use according to one of claims 1 to 7, characterized in that a mixture is used, consisting of:
Component i)
Component ii)
any mixture of components iii) to viii), but at least one of these components must be present. 8. Use according to one of claims 1 to 8, characterized in that that the mixture by supplying electromagnetic radiation is polymerized, preferably by irradiation with light of the Wavelength from 350 to 1000 nm. 9. Use according to one of claims 1 to 8, characterized in that that immediately after applying the mixture, the hard tooth substance with cationically and / or radically polymerizable material is overlaid. 10. Use according to claims 1 to 10, characterized in that the hard tooth substance is not etched before applying the adhesive system.