DE19918974A1 - Self-etching dental materials containing polymerizable phosphonic acids, used e.g. as bonding, filling or sealing materials - Google Patents

Abstract

Dental materials contain polymerizable (meth)acryloyloxyalkanephosphonic acids (I). Dental materials comprise phosphonic acids of formula (I). R1 = H or methyl; n = 1-11.

Description

The present invention is directed to one polymerizable dental material with high Bond strength to the tooth base and one self-etching ability.

In particular, the invention relates to a Dental material based on polymerizable, ethylenically unsaturated monomers, which a Have phosphonic acid group, as in the general Formula I are shown.

As new dental materials within the scope of the invention Cements, compomers, composites, filling materials, Sealer and veneering plastics as well as adhesives for Veneering plastics for dental applications.

Plastics have been experiencing an increasing trend lately Importance in the field of tooth restoration. It exists but still a need for plastics for dental Applications compared to those on the market Materials have improved properties.

As plastics for dental applications Dental materials based on polymerizable, established ethylenically unsaturated monomers. Typically, acrylic derivatives have low affinity for natural tooth enamel. To increase that affinity, various functional groups, such as Phosphoric acid and phosphoric acid derivatives, to the ethylenic unsaturated monomers coupled.  

DE 195 44 673 or EP 0 115 948 are acrylic derivatives known, which has an ester bond with phosphoric acid or phosphoric acid derivatives. This Ester linkage is a potential weak point which can lead to material failure.

From DE 28 18 068 it can be seen that in the Connection of the acrylate units to the phosphorus-containing one Group via a P-C bond a more permanent anchor is achieved on the tooth base because the hydrolyzable Unity is missing. In the above-mentioned patent however, without exception, acrylic substituted Alkylphosphinic acids to solve the sticking problem presented. To ethylenically good adhesion to reach unsaturated monomers to the tooth base, it is necessary to remove the tooth base before inserting the Etch contents into the placed cavity. The dentist has to therefore two separate ones to carry out this work Take steps to get a good result receive.

In light of what is stated and discussed herein State of the art was therefore an object of the invention to provide an improved dental material that in particular a stronger and more permanent connection to the Causes tooth base.

The solution of this and others not in detail named, but from the introductory discussion of the State of the art derivable or easily tapping tasks succeed through a dental material according to claim 1.

The fact that the dental material phosphonic acids of the general formula I,

wherein
R ¹ = H, methyl and
n is an integer between 1 and 11,
As a polymerizable component, it is possible to obtain tooth filling materials which achieve an extremely strong and permanent connection of the filling body to the tooth base with good adhesion which is constant compared to the prior art.

Dental materials which are particularly suitable for the abovementioned use have a methyl group as the radical R ¹ and / or have an n of 1 to 3 in the phosphonic acids of the general formula I.

Phosphonic acids of the general formula I can be prepared by reacting the compounds of the general formula II with phosphoric acid dialkyl esters of the general formula III to give monoalkylphosphonic esters of the general formula IV (Scheme 1),

Scheme 1

where R ^{2 is} H or acetyl and m = n - 2 is n ≧ 2, and R ³ and R ^{4 can} independently represent a linear or branched (C ₁ -C ₄ ) alkyl radical. Methyl, ethyl, n-propyl, n-butyl, isopropyl, sec-butyl, isobutyl, tert-butyl can be used as alkyl radicals.

In the case of R ² = acetyl, the compound of the general formula IV is hydrolyzed before its further processing to the general compound of the formula IV with R ² = H.

Then compounds of the general formula IV with R ² = H are reacted with compounds of the general formula V (Scheme 2),

Scheme 2

whereby compounds of the general formula VI are obtained in which R ² to R ^{4 have} the meaning given above and R ^{1 is} H or methyl.

In the case of n = 1, the starting substance IV can be bought acquireable.

Finally, the compound is hydrolyzed general formula VI to the desired products of the general formula I (Scheme 3).

Scheme 3

The reaction shown in Scheme 1 is preferred without Addition of a solvent in bulk. This  The reaction sequence is already described in Houben-Weyl, 4th ed., Vol. XII / 1, p. 463 ff.

If there is an acetyl group instead of R ² , the necessary hydrolysis can preferably be carried out using an alkali metal hydroxide in an alcohol; the use of KOH and methanol as base and solvent is very particularly preferred in this connection (as described in DE 30 21 264 C2) ).

The implementation from scheme 2 can, for. B. after the unicorn Variant in an inert organic solvent Pyridine is added as base. However, it is also an analogous implementation according to Schotten-Baumann in a two-phase System conceivable.

Can be used as inert organic solvents 1,2-dichloroethane, toluene, xylenes, dichlorobenzene are used become.

The cleavage of the linear or branched alkyl groups of the general formula VI can preferably in an inert organic solvent with the addition of ethyl acetate Trimethylbromosilane and then with methanol. Suitable inert organic solvents can be Chloroform, dichloromethane, carbon tetrachloride used become.

According to the invention, the dental material can have Phosphonic acids of general formula I as more effective Be part of a bonding.

By using the compared to the Dialkylphosphinic acids from DE 28 18 068 are much more acidic Phosphonic acids of the general formula I have an effect on them therefore as a self-etching component in self-etching Bondings.  

The phosphonic acids of the general Formula I in dental materials such as cements, compomers, in Composites, filling materials, sealants and Facing plastics or adhesives for Veneering plastics.

By making aqueous solutions of the new phosphonic acids the general formula I used in dental materials, one arrives in accordance with the invention and in a particularly advantageous manner Way to new self-etching dental materials. Of the The advantage of these materials is that despite being strong and permanent bond to the tooth base possess self-etching property that it gives the dentist allowed, contrary to the state of the art with a Step the dental material in the cavity of the Anchor tooth. The state of the art describes just systems made by mixing several Components are able to act in a similar way.

The bonds have in particular a composition of the components i to iv, the sum of the components i to iv totaling 100% by weight and the component

• i) 5-80% by weight of water,
• ii) 1-90% by weight phosphonic acid of the general formula I,
• iii) 0.5-5% by weight of conventional additives,
• iv) 5-90% by weight of a further monomer,
• v) 0 to 20% filler and
• vi) 0 to 50% of other solvents

is.

Common additives can be initiators, accelerators, Be stabilizers. Other solvents can be Acetone, ethanol.

Other monomers that can be considered, for example come triethylene glycol dimethacrylate (TEGDMA), Tetraethylene glycol dimethacrylate, glycerol dimethacrylate  (GDMA), glycerol dimethacrylate, Bowen monomer, Hydroxyethyl methacrylate, urethane dimethacrylates, Polyethylene glycol dimethacrylates. This enumeration is exemplary and not exhaustive.

Fillers are u. a. Glasses in irregular and spherical Form, aerosils, hydroxylapatites, prepolymers, Polysiloxanes and / or layered silicates. Under Layered silicates are silicates with infinite 2-dimensional structures understood, which may can be hydrophobized, u. a. Bentonite. The eye contained fillers are described in DE 196 40 454 executed.

The following examples are intended to illustrate the invention clarify, but in no way limit them.

I) Manufacturing examples Synthesis of 2-acetoxyethanephosphonic acid dimethyl ester

In a 2 l three-necked flask with a reflux condenser and The dropping funnel becomes 1000 g of dimethyl phosphite (9.1 mol) submitted and heated to 120 ° C under nitrogen. On the The dropping funnel becomes a solution over a period of 2 hours consisting of 200 g vinyl acetate (2.3 mol), 19.0 g AIBN (0.12 mol) and 278 g of dimethyl phosphite (2.5 mol) were added dropwise. When the addition has ended, the mixture is stirred at 120 ° C. for 2 hours continued stirring, cooled and the excess Dimethylphosphite separated by vacuum distillation.

The residue is fractionated in an oil pump vacuum distilled.

395 g of a colorless liquid (2.01 mol; yield: 88%) are obtained at 93 ° C./0.5 torr.
¹ H NMR (CDCl ₃ ): 2.04 ppm (s, 3H); 2.20 (m, 2H), 3.75 (d, 6H); 4.30 (m, 2H)

Synthesis of 2-hydroxyethanephosphonic acid dimethyl ester

274 g of dimethyl 2-acetoxyethanephosphonate (1.4 mol), 445 g of methanol (13.9 mol) and 2 g of potassium hydroxide are stirred at room temperature for 2 hours. The excess methanol and the methyl acetate formed are distilled off on a rotary evaporator. The residue is distilled under high vacuum (112 ° C / 0.05 Torr).
184.5 g of the colorless liquid correspond to a yield of 86%.
¹ H NMR (CDCl ₃ ): 2.12 ppm (m, 2H), 3.75 (d, 6H); 3.88 (m, 2H); 4.35 (s, 1H)

Synthesis of 2-methacryloxyethanephosphonic acid dimethyl ester

38.5 g of dimethyl hydroxyethanephosphonate (250 mmol) are dissolved in 150 ml of dry dichloromethane. 23.7 g pyridine (300 mmol) are added and the solution is cooled to 0 ° C. 31.4 g of methacrylic acid chloride (300 mmol) are added dropwise so that the temperature of the solution does not exceed 5 ° C. After the addition has ended, the mixture is stirred at 0 ° C. for 30 min and then at 25 ° C. for 2 hours. Then 5 ml of methanol are added and the solvent is distilled off. The residue is separated by means of column chromatography on silica gel (eluent: 1. ethyl acetate; 2. tetrahydrofuran). The product is the last fraction.
Yield: 24 g of a colorless liquid (108 mmol; 43%)
¹ H NMR (CDCl ₃ ): 1.95 ppm (s, 3H); 2.25 (m, 2H); 3.75 (d,
6H); 4.40 (m, 2H); 5.62 (s, 1H); 6.13 (s, 1H)

Synthesis of 2-methacryloxyethanephosphonic acid-bis- trimethylsilyl ester

15 g of dimethyl 2-methacryloxyethanephosphonate (67.5 mmol) are dissolved in 40 ml of dry dichloromethane and mixed with 0.5 g of ethyl acetate. With stirring slowly added 21.70 g of trimethylbromosilane (142 mmol). The solution is dissolved for 1 hour at room temperature. Then all volatile components of the Solution removed in vacuo. What remains is 22.90 g colorless liquid that is not further processed, but is fed directly to the methanolysis.

Synthesis of 2-methacryloxyethanephosphonic acid

22.90 g of 2-methacryloxyethanephosphonic acid bis-trimethylsilyl ester (crude product) are mixed with 20 ml of methanol (anhydrous) and stirred for 15 minutes at room temperature. The volatile solution constituents are separated off in vacuo. The residue is freed from by-products at 50 ° C. on a Kugelrohr (0.2 Torr). 12.84 g of the slightly viscous liquid correspond to a yield of 98% (based on 2-methane acryloxyethanephosphonic acid dimethyl ester).
¹ H NMR (CDCl ₃ ): 1.92 ppm (s, 3H); 2.27 (m, 2H); 4.40 (m, 2H); 5.60 (s, 1H); 6.11 (s, 1H), 9.60 (s, 2H)
The representation of:
3-Acetoxypropanephosphonic acid dimethyl ester
Starting from allyl acetate, the product was obtained in a yield of 82%.
Boiling point: 106 ° C / 0.5 Torr
¹ H NMR (CDCl ₃ ): 1.85 ppm (m, 2H); 1.95 (m, 2H); 2.08 (s, 3H); 3.75 (d. 6H); 4.12 (t, 2H)
3-hydroxypropanephosphonic acid dimethyl ester
Yield: 96%
The product was not distilled to avoid decomposition.
¹ H NMR (CDCl ₃ ): 1.88-1.95 ppm (m, 4H), 3.65 (t, 2H); 3.75 (d. 6H); 3.92 (s, 1H)
3-methacryloxypropanephosphonic acid dimethyl ester
Yield: 36%
¹ H NMR (CDCl ₃ ): 1.85-1.95 ppm (m, 5H); 2.15 (m, 2H); 3.75 (d. 6H); 4.28 (m, 2H); 5.62 (s, 1H); 6.13 (s, 1H)
3-methacryloxypropanephosphonic acid bis-trimethylsilyl ester
Yield: 96% (crude product)
3-methacryloxypropanephosphonic acid
Yield: 95%
¹ H NMR (CDCl ₃ ): 1.84-1.92 ppm (m, 5H); 2.14 (m, 2H); 4.25 (m, 2H); 5.60 (s, 1H); 6.11 (s, 1H), 9.70 (s, 2H)

Synthesis of diethyl methacryloxymethylphosphonate

6.32 g (37.6 mmol) of diethyl hydroxymethylphosphonate (Aldrich) are dried in 20 ml. Dissolved dichloromethane and 3.57 g pyridine (45 mmol) added. It is cooled to 0 ° C. 4.70 g (45 mmol) methacrylic acid chloride are added dropwise so that the temperature of the solution does not exceed 5 ° C. After the addition has ended, the mixture is stirred at 0 ° C. for 30 min and then at 25 ° C. for 2 hours. Then 5 ml of methanol are added and the solvent is distilled off. The residue is separated by means of column chromatography on silica gel (eluent: 1st ethyl acetate). The product is the last fraction.
Yield: 4.8 g of a colorless liquid (20.3 mmol; 54%)
¹ H NMR (CDCl ₃ ): 1.34 ppm (t, 6H); 1.97 (s, 3H); 4.18 (m, 4H); 4.48 (d. 2H); 5.6l (s, IH); 6.16 (s, 1H)

Synthesis of methacryloxymethylphosphonic acid

Synthesis analogous to the higher homologues.
Yield: 95%
¹ H NMR (CDCl ₃ ): 1.94 ppm (s, 3H); 2.27 (m, 2H); 4.4 (m, 2H); 5.62 (s, 1H); 6.18 (s, 1H), 10.40 (s, 2H)

Examples of compositions

Application test, adhesive strength to dentin and enamel:
The suitability of the new monomers is checked by the adhesive strength to dentin and enamel in a tensile test. Such a test arrangement is shown in Fig. 1. An adhesive mask 2 is applied to a cattle tooth 1 . The bonding 3 sits directly on the tooth 1 in the recess of the adhesive mask 2 . The plastic filling material 4 , on which a metal cylinder 5 with a bore 6 is seated, is attached to the bonding 3 . The cattle teeth 1 come from a herd. After extraction, they are stored for a maximum of 1 month until processing at -33 ° C. The bovine teeth 1 are carefully mechanically cleaned before preparation. Then they are ground by wet grinding on SiC papers with grain sizes 240 and 600 to such an extent that a sufficiently large and near-melting dentine surface is available. After rinsing with deionized water and drying in a stream of compressed air, an adhesive mask 2 with a punched-out area of 4 mm in diameter is adhered to the dentin / enamel. Preparation 3 is then applied to the dentin with a disposable brush, and is left to act for 30 s. The mixture is then dried in a stream of compressed air for 5 s and exposed to a Degulux (Degussa) polymerization light for 20 s. Finally, the plastic filling material 4 Degufill mineral (Degussa) is applied in a thin layer to the hardened bonding layer 3 and exposed to the polymerization lamp for 40 s. A metal cylinder 5 (diameter: 6 mm) is then glued to the plastic filling material 4 using a two-component superglue. This metal cylinder contains a bore 6 at the upper end so that the sample can be fastened in the sample holder of the universal testing machine with a pin (see Fig. 1). After the preparation, the samples are stored in a 0.1% aqueous chloramine T solution at 37 ° C. for 24 hours. The tensile strength is carried out at a crosshead speed of 1 mm / min. The adhesive strength results from the tensile force and the adhesive surface on the tooth, which is determined by the punched out in the adhesive mask 2 . The tensile adhesive strength is determined in each case on 6 samples and given as their mean value.

For the same preparations, the Tensile adhesive strength determined on bovine enamel. Here will proceed analogously to the preparation on dentin.

Claims (9)

1. Dental material comprising phosphonic acids of the general formula I
wherein
R ¹ = H, methyl and
n is an integer between 1 and 11. 2. Dental material according to claim 1, characterized in that R ¹ = methyl. 3. Dental material according to claim 1, characterized, that n = 1 to 3. 4. Dental material according to one or more of the Claims 1 to 3, characterized, that this is a bonding. 5. Bondings according to claim 4, consisting of

• i) 5-80% by weight of water,
• ii) 1-90% by weight of phosphonic acid of the general formula I,
• iii) 0.5-5% by weight of conventional additives,
• iv) 5-90% by weight of monomers,
• v) 0 to 20% fillers,
• vi) 0 to 50% other solvents, where i) -vi) together gives 100% by weight.

6. Dental material according to one or more of the Claims 1 to 3, characterized, that this is a cement for dental applications. 7. Dental material according to one or more of the Claims 1 to 3 characterized, that this is a compomer for dental applications. 8. Dental material according to one or more of the Claims 1 to 3, characterized, that this is a composite, filling material, sealer and is veneering plastic for dental applications. 9. Dental material according to one or more of the Claims 1 to 3, characterized, that this is an adhesive for veneering plastics for dental applications.