CA2199624C - Polymerizable aromatic carboxylic acids and carboxyanhydrides with cyclic carbonate groups, as well as preparations containing these compounds - Google Patents

Abstract

The invention relates to new polymerizable aromatic carboxylic acids and carboxyanhydrides with cyclic carbonate groups and preparations of these compounds, preferably for use in dental technology.

Description

Patent Application Heraeus Kulzer GmbH
Polymerizable Aromatic Carboxylic Acids and Carboxyanhydrides with Cyclic Carbonate Groups, as well as Preparations Containing these Compounds The invention relates to new polymerizable aromatic carboxylic acids and carboxyanhydrides with cyclic carbonate groups and preparations of these compounds, preferably for use in dental technology.

In conservative dentistry, it is particularly difficult to achieve long-lasting adhesion (without the development of marginal clefts) of plastic filling materials to the hard tissues of the tooth (dentine and enamel). In dentistry, curable materials are used as filling materials for repairing teeth. Generally, the preferred curable materials are filling materials on an acrylate basis which are cured by means of radical polymerization. These materials have the disadvantage of shrinking during the curing process and thus contribute to the formation of marginal clefts.
Plastic fillings have the additional disadvantage of not adhering well to the dentine.

To improve bonding to the hard tissue of the tooth, adhesives or adhesive agents can be used. An example of an effective component of such adhesives for dental fillings are methacryloyloxyalkyl derivatives of aromatic carboxylic acids. US 4 148 988, for example, describes mixtures of trimellitic-acid-4-methacryloyloxyethylester (4-MET) or trimellitic-acid anhydride-4-methacryloyloxyethylester (4-META) with ethylenically unsaturated monomers and polymerization initiators.

O O O O
O OH
I
O OH O

O O

A commercial product (Superbond by Sun Medical), which is based on 4-META, must be mixed with methyl methacrylate (MMA), polymethyl methacrylate (PMMA) and partly oxidized tri-n-butylboran (TBB) to retain its ready-to-apply form (MMA-4-META-TBB-Resin).

EP 0 471 252 Bl recommends N-alkyl-N-(meth)acryloyloxyalkylcarboxamides of aromatic carboxylic acids and carboxyanhydrides as components for adhesives.
These (meth)acryloyloxyalkyl derivatives clearly result in simplified application formulations.

A disadvantage of the known (meth)acryloyloxyalkyl derivatives of aromatic carboxylic acids is their relatively poor ability to polymerize. This has several serious drawbacks. For example, curing can be incomplete, residual monomers can remain, and stringent conditions, such as long exposure times, are necessary for the curing process.

It has now been found that with the aid of the new polymerizable aromatic carboxylic acids and carboxyanhydrides, cyclic carbonate groups can be used to formulate adhesives which are particularly well-suited for treating the hard substance of teeth, since their ability to polymerize is clearly improved.

The new compounds are in accordance with the following Formula (I), Xm (HOOC)~ Ph A~
Y
P
Jq w here Ph represents a three or four times substituted phenyl ring (1,2,3/1,2,4 or 1,2,4,5 substitution), or a three or four times substituted naphthalene ring (1,2,6/1,4,5/2,3,6/1,4,5,8 or 2,3,6,7 substitution),, A is the (m+p+l)valent aliphatic remainder with 3 to 15 C
atoms which can be substituted with OH groups and contain up to 5 ether bonds, X is a methacrylate or acrylate group, /,O
O-~( Y is O ~ p\O
O
n is 2 or 3, m is 1, 2, 3 or 4, p is l, 2, 3 or 4, q is l or 2.

The aliphatic remainder A can be linear, branched or cyclic.
Linear or branched remainders are particularly preferred.
The following are examples of especially well-suited aliphatic remainders A:

CHZ

-CHZ CH-CH2 , CH2 i CH 2 HO-CH2--C-CHz -CHZ C-CHZ

I or -CHZ C-CHZ-O-CHZ C-CHZ CH2 ~ HZ

Two COOH groups can also be combined with an anhydride group, provided that the two COOH groups are bonded on aiz adjacent aromatic compound. Ortho-positions on benzol and naphthalene rings are regarded as adjacent, as well as the positions (1.8 or 4.5 substitution) on naphthalene rings.
PH means a phenyl ring substituted three times in 1, 2, 3 or 1, 2, 4 position, or four times in 1,2,4,5 position, or a naphthalene ring substituted three times in 1, 2, 6 position, in 1, 4, 5 position or 2, 3, 6 position, or four times in 2, 3, 6, 7 or 1, 4, 5, 8 position.

The following are individual examples of polymerizable aromatic carboxylic acids and carboxyanhydrides with cyclic carbonate groups.

Table 1 Carboxylic Acids and Carboxyanhydrides According to the Invention No. Formula No. Formula o ~o o 0 ~-o o oH ~-o ~o O~ { Oy O OH O_ 1 OO O
~ \/
~\/ 0 0 y o ~o 0 0 0 p o 0 ~O O OH ~p ~O
O O OH p~Oyp O y O 0 o ~o 0 0 0\\ ~p 0 0 p ~O O OH J-p ~ O
, 1~O HO ~ OH Ov\ip~( ~ O~~~JJJ 0 O I p p l p HO ~ O
' 7 ~

o p o O O O
O

a 0 O O
~ O
0 pO o a a No. Formula No. Formula ~ o 0 0 0 o o 0 0 0 ' ~ o ~
p~o~,o ~
p ~ o 0 o p / ~ O~ O~
~ o~J J 0 O ro ~

p ~

~ o 0 0 ~
\ O O O / ~ O O O \ ~ OH
O O O ~ ~ ~ O
O O
o~o oO O ao 0~y a oa ~ ~
o ~-o ~-O 0 a 0 o 0 ~ 0 O H O~ ~ ~11 Oy OH y O 0 0 ~

o a o pH \\ O 0 /\ O
O~\ >-'O 0 l-0 ~O ol- ~--0 a O~OyO \ / OH OyO

Q

-8a-No. Formula No. Formula = w, ~ 0 0 O
x o O0 ~ 'r \ol o ~p~ ' O
0 Ol 0 \

The polymerizable aromatic carboxylic acids and carboxyanhydrides according to the invention are produced in the most expedient manner by the conversion of aromatic monoanhydrides or dianhydrides with multifunctional hydroxyalkyl(meth)acrylates of Formula (II), xm HO-A\

YP (II), where A, X, Y, m and p are as described above.

The preferred monoanhydrides are the commercially available trimellitic acid derivatives 1,2,4-benzoltricarboxylic-acid-anhydridechloride and 1,2,4-benzoltricarboxylic-acid-anhydride, the hemimellitic acid derivatives 1,2,3-benzoltricarboxylic-acid-anhydride and 1,2,3-benzoltricarboxylic-acid-anhydridechloride (known from the literature), and the naphthalenetricarboxylic-acid derivatives 1,2,6- and 1,4,5-naphthalentricarboxylic-acid-hydridechloride.

Preferred as dianhydrides are the commercially available compounds benzol-1,2,4,5-tetracarboxylic acid dianhydride (pyromellitic-acid-dianhydride), naphthalene-1,4,5,8-tetracarboxylic-acid-dianhydride and naphthalene-2,3,6,7-tetracarboxylic-acid-dianhydride, which is simply formed by dehydration from the known naphthalene-2,3,6,7-tetracarboxylic acid.

The hydroxyalkyl(meth)acrylates of Formula (II) below, on which the polymerizable aromatic carboxylic acids and carboxyanhydrides according to the invention are based, are accessible through the step-by-step esterification of polyhydroxyalkyl compounds, e.g. with (meth)acrylic acid chloride and the chloroformic acid ester of Formula (III).
O
HO_A ~X CI 04 \ O ~/~/ J O
YP (11)~ ~ (ill) O
The chloroformic acid ester according to Formula (III) can be produced through phosgenation of glycerol. This step in the synthesis is described in detail in US 2 446 145.
Preferably, polymerizable aromatic carboxylic acids and carboxyanhydrides according to the invention are produced in an organic solvent. Preferred organic solvents are aprotic solvents such as dioxane, tetrahydrofuran, N,N-dimethyl-formamide, N,N-dimethylacetamide, dimethylsulfonamide and acetone. Toluene and diethylether are preferred. Xylol, methylene chloride, chloroform and methyltert.-butyl ether are particularly preferred.

A suitable temperature range for the polymerizable aromatic carboxylic acids and carboxyanhydrides according to the invention lies between -30 C and 110 C. A reaction between -10 C and 50 C is preferred, and between -5 C and 30 C in particular. Additional organic or inorganic bases can be used in the production.

Preferred inorganic bases are the weak basic carbonates and bicarbonates of sodium and potassium. Preferred organic bases are tertiary amines, with triethylamine and pyridine being especially preferred. Related to the anhydride, the bases are used in an equimolar quantity to 5 times the molarity, with an excess of 2 to 3 times the molarity preferred. In addition, the bases also promote solution.

To produce the polymerizable aromatic carboxylic acids with adjacent carboxylic acid groups according to the invention, first the anhydrides in question can be synthesized. From the anhydrides, the dicarboxylic acids are accessible through hydrolysis at temperatures between 5 C and 100 C, preferably between 20 C and 50 C. Hydrolysis can occur following isolation of the anhydrides, but direct hydrolysis of the reactants is also possible. To carry out hydrolysis, add water in equimolar quantity, preferably in a quantity 10 times the molarity. Hydrolysis can be catalyzed by the specific addition of acids, primarily of sulfuric acid, phosphoric acid, toluenesulfonic acid or acid ion exchangers, or by the addition of bases such as sodium and potassium hydroxide, carbonate or bicarbonate.

The reactivity of compounds curable by polymerization can be characterized very well by means of the photo DSC method (Differential Scanning Calorimetry)-With this method, photo-activated samples are irradiated in a DSC apparatus with an intensive radiation source, such as a halogen lamp with a heat filter. During irradiation, the heat flow is recorded as a function of time. As a reference, samples of the same composition are used without photo initiator. As a measure of the reaction rate, the t-max value is determined, with t-max indicating the time from the onset of irradiation until the maximum reaction (maximum heat flow) is reached. The smaller the t-max is, the larger the photo reactivity.

In addition to the new polymerizable aromatic carboxylic acids and carboxyanhydrides (I), the preparations according to the invention contain solvents, initiators, coactivators and, in some cases, also other (meth)acrylic-acid esters as comonomers. Mixtures of several polymerizable aromatic carboxylic acids and carboxyanhydrides (I) can also be used in the preparations according to the invention.

The solvents of the preparations are meant to dissolve the components and must be non-toxic if the preparations are meant for dental purposes. Water and volatile organic solvents such as methanol, ethanol, propanol, isopropanol, acetone, methylethylketone, acetic acid methylester and ethylester and tetrahydrofuran are preferred. In general, use 10 to 1000% by weight, preferably 50 to 300% by weight of the solvent, related to the polymerizable aromatic carboxylic acids and carboxyanhydrides (I). The use of mixtures of these solvents is especially preferred, in particular, aqueous mixtures.

Initiators in the sense of this invention are radical formers which trigger radical polymerization. Photo-initiators are preferred, which, under the influence of light such as UV light, visible light or laser light, trigger radical polymerization.

The so-called photopolymerization initiators are known from the literature. They are, preferably, monocarbonyl or dicarbonyl compounds such as benzophenone, benzoin and its derivatives, particularly benzoinmethylether, benzil and benzil derivatives, and other dicarbonyl compounds such as diacetyl, 2,3-pentanedione and a-diketo derivatives of norbornane and substituted norbornanes, metallocarbonyls such as pentacarbonylmangane or quinones such as 9,10-phenanthraquinone and naphthoquinone. Camphoquinone is particularly preferred.

The preparations according to the invention generally contain 0.01 to 201 by weight, preferably 0.1 to 0.5% by weight of the initiator, related to the quantity of polymerizable compounds.

If one of the components in contact with the preparation according to the invention already contains an initiator of the type described, an initiator need not be added to the preparation.

It can be advantageous to add coactivators to the preparations according to the invention, which accelerate the polymerization reaction. Known coactivators are, for example, amines such as p-toluidine and dimethyl-p-toluidine, trialkylamines such as trihexylamine, polyamines such as N,N,N',N'-tetraalkylalkylenediamine, barbituric acid and dialkylbarbituric acids. Especially preferred are dimethylaminobenzolsulfonamides according to DE-A 31 35 113.
The coactivators are generally used at a quantity of 0.02 to 4% by weight, preferably 0.2 to lo by weight, related to the quantity of polymerizable compounds.

Other potential components of the preparations according to the invention are (meth)acrylic-acid esters as comonomers.
Preferred, for example, is the ester of (meth)acrylic acid with monovalent to pentavalent alcohols with 2 to 30 C
atoms. Especially preferred are epoxy(meth)acrylates and urethane(meth)acrylates.

Derivatives of tricyclodecane (EP-A 023 686) and conversion products from polyols, diisocyanates and hydroxyalkylmethacrylates (DE-A 37 03 120, DE-A 37 03 080 and DE-A 37 03 130) should also be mentioned.

The so-called Bis-GMA of the following formula is especially preferred as a (meth)acrylic-acid ester:

O O
O--~O O__~ O it'r OH OH

It is possible to use mixtures of the different (meth)acrylic acid esters, e.g. mixtures of 20 to 70o by weight of Bis-GMA and 30 to 80% by weight of triethyleneglycoldimethylacrylate.
The preparations, according to the invention, can also contain up to 10% by weight of common additives such as stabilizers, inhibitors and antifading agents.

The preparations according to the invention can be produced by mixing the polymerized aromatic carboxylic acids and carboxyanhydrides (I), the solvent, the initiator and, if applicable, by mixing the other components with each other by means of vigorous agitation.

The preparations according to the invention are preferably used as adhesives, especially for improving the adhesion of polymerizable dental materials to the hard tissues of teeth (enamel and collagen-containing dentine).

The collagen-containing tooth tissue is conditioned in a special embodiment prior to treatment with the preparations according to the invention, with a liquid that has a pH
value in the range of 0.1 to 3.5. This conditioning liquid generally contains acids with a pKa value of less than 5 and, in some cases, an amphoteric amino compound with a pKa value in the range of 9.0 to 10.6 and a pKa value in the range of 11.5 to 12.5. The following acids can be contained, for example, in the conditioning liquid:

phosphoric acid, nitric acid, pyruvic acid, citric acid, oxalic acid, ethylenediaminetetraacetic acid, acetic acid, tartaric acid, malic acid. The conditioning liquid can also contain substances from the group of polyethylene glycols and metal hydroxides. In particular, the above-named polybasic acids can also be used as metallic salts in some cases, as long as free acid functions remain.

For example, the preparations according to the invention can be used as adhesives, as follows:

In dental repair work, following a mechanical cleaning of the collagen-containing tooth tissue, the conditioning liquid is first applied with some cotton and left to act for a short period (e.g. 60 seconds). Then the tooth material is rinsed with water and dried in an airstream. Next, a thin layer of the preparation according to the invention is applied, for example with a small brush, and dried in an airstream. Then the actual filling material, such as a plastic filling material customary in dentistry, is applied.

In addition to their use as preparations suitable for adhesives, the polymerizable carboxylic acids and carboxyanhydrides according to the invention can also be used to particular advantage in admixing liquids for glass ionomer cement, as well as in bone cement.

Experiments Examples 1 to 3 Production of Polymerizable Carboxylic Acids and Carboxyanhydrides according to the Invention Example 1 Production of Compounds 1 and 2 in Table 1 In 500 mL of dry butanone, 160.2 g glycerolmonomethacrylate (1 mol; by Polyscience, Inc.) and 202 g (1 mol) triethylamine were dissolved. The formulation was cooled to -5 C, and a drip inflow was added that consisted of 210.57 g trimellitic-acid anhydridechloride and 180.6 g (1 mol) chloroformic-acid ester of Formula (III), dissolved in 400 mL of dry butanone. When this addition was completed, the solution was agitated for 16 hours at 0 C. The resulting precipitate was cold-filtered, the filtrate rinsed with 0.1 n hydrochloric acid and water, the organic phase was separated and dried over sodium sulfate.

The resulting butanone solution contains compound 2 in Table 1 and can be used directly for the hydrolysis of the remaining anhydride groups. To do this, 50 mL of deionized water was added to the solution and agitated at room temperature for a period of 16 hours. After adding 200 mg of 2.6-di-tert.-butylkresol, the resulting solution can be concentrated to 372.1 g(75o Th.) of a yellowish viscous oil (compound 1 in Table 1).

IR: = 3400, 3200, 2950, 2600, 2400, 1800, 1735, 1640, 1490, 1460, 1390, 1290, 1250, 1185, 1100, 1060, 960, 870, 787, 715 cm-1.

'H-NMR (CDCI3, 200 MHZ): = 8.6-7.8 (3 H); 6.2 and 5.7 (1 H
each); 5.2 (1 H); 4.8-4.3 (9 H); 1.9 (3 H) ppm.

Example 2 Production of Compound 6 in Table 1 In 500 mL of dry butanone, 160.2 g glycerolmonomethacrylate (1 mol; Polyscience, Inc.) and 202 g (1 mol) triethylamine were dissolved. The formulation was cooled to -5 C and a drip inflow was added that consisted of 327.18 g (1.5 mol) pyromellitic acid anhydride and 180.6 g (1 mol) chloroformic acid ester of Formula (III) dissolved in 400 mL
of dry butanone. When this addition was completed, the solution was agitated for 2 hours at 0 C, then for 14 hours at room temperature. Then the resulting precipitate was filtered, the filtrate was rinsed with 0.1 n hydrochloric acid and water, the organic phase was separated and dried over sodium sulfate.

The resulting butanone solution contains the desired compound 6 in Table 1. After adding 200 mg of 2,6-di-tert.-butylkresol, the solution can be concentrated to 292.5 g(450 of Th.) of a yellowish viscous oil (compound 5 in Table 1).

IR: = 3400, 3050, 2950, 2550, 2350, 1800, 1720, 1640, 1550, 1495, 1460, 1390, 1350, 1250, 1170, 1115, 1060, 950, 760, 695 cm-1 'H-NMR (acetone-d6, 200 MHZ): = 8.3-8.0 (2 H); 6.1 and 5.65 (1 H each); 5.1 (1 H); 4.8 (1 H), 4.3-4.2 (9 H); 1.9 (3 H) ppm.

Example 3 Production of Compound 15 in Table 1 In 500 mL of dry butanone, 160.2 g glycerolmonomethacrylate (1 mol; Polyscience, Inc.) and 202 g (1 mol) triethylamine were dissolved. The formulation was cooled to -5 C, and a drip inflow was added that consisted of 402.27 g (1.5 mol) naphthalene-1,4,5,8-tetracarboxylic-acid dianhydride and 180.6 g(i mol) chloroformic-acid ester of Formula (III), dissolved in 400 mL of dry butanone. When this addition was completed, the solution was agitated for 2 hours at 0 C, then for 14 hours at room temperature. Next, the resulting precipitate was filtered, the filtrate was rinsed with 0.1 n hydrochloric acid and water, the organic phase was separated and dried over sodium sulfate.

The resulting butanone solution contains the desired compound 15 in Table 1. After adding 200 mg of 2.6-di-tert.-butylkresol, the solution can be concentrated to 253.6 g(350 of Th.) of a yellowish viscous oil.

IR: = 3400, 3050, 2925, 2500, 2300, 1940, 1800 - 1700, 1640, 1600, 1490, 1440, 1390, 1300, 1155, 1050, 955, 890, 820, 765, 720 cm-1.

Example 4 Testing the photoreactivity of the (meth)acryloyloxyalkylesters by means of the photo DSC
method (Differential Scanning Calorimetry).

The following components were combined by means of vigorous agitation:

5.0 g (Meth)acryloyloxyalkylester mg Camphoquinone 25 mg p-dimethylaminobenzol-sulfonic-acid-N,N-10 diallylamide (DASA) Camphoquinone and p-dimethylaminobenzol-sulfonic-acid-N,N-diallylamide form the photo initiator system.

The samples were irradiated at 30 C in a DSC apparatus with a 75 W halogen lamp with heat filter. During irradiation, the heat flow was recorded as a function of time. As a reference, samples of the same composition were used without photo initiator. During the test, nitrogen rinsing was carried out. As a measure of the reaction rate, the t-max value was determined, with t-max indicating the time from the onset of irradiation until the maximum reaction (maximum heat flow) is reached. The smaller the t-max, the larger the photo reactivity.

(Meth)acryloyloxyalkylest t-max (min) er Compound 1 in Table 1 0.63 Compound 2 in Table 1 0.47 4-MET (control) 1.1 Example 5 Inhibition of polymerization through oxygen To test the susceptibility of the monomers to inhibition, the thickness of the non-polymerized surface layer is determined in samples that were irradiated with light according to example 4.

Cylindrical forms (6 mm in diameter, 0.5 mm high) drilled into a rectangular brass plate are filled in three layers with the monomer to be tested. After evaporating the solvent, they are irradiated for 20 seconds with the Translux CL light emitter by Heraeus Kulzer GmbH at ambient atmospheric conditions and dusted with a very slightly colloidal silver powder. Then the brass plate is placed on the table of a direct-light microscope against a rectangular frame holder. The table position can be adjusted in the x and y direction by means of two servomotors, with a reproducibility of 1 m. In constant y position, the vertical coordinates z are determined at a distance of 1 mm along the x axis according to the depth of field method.
The z value is determined via a displacement pickup attached vertically to the plane of the table, which indicates the height setting in micrometres via a calibrated voltmeter.
The reproducibility of the z value determination is 1 m.
Immediately after the initial value is determined, the sample surface is thoroughly rinsed with ethanol. The form is then taken back to the microscope table, and after running the x/y initial positions, the z values are again determined. The differences between the first and second measurements are recorded as means and correspond to the surface layer not polymerized due to inhibition by oxygen.
For each monomer, three samples are produced and measured.
The thinner the non-polymerized surface layer (inhibition layer), the lower the oxygen inhibition, the better the curing and thus the mechanical strength of the polymer and the total adhesive system.
Results Non-polymerized surface layer ( m) Compound 2 in Table 1 1.3 0.8 4-MET (control) can be completely washed off, i.e. no curing Only the compound according to the invention shows curing with a very slight inhibition layer.

Examples 6 and 7 Production of preparations for use as adhesive Example 6 A preparation according to the invention for use as an adhesive is produced by intensive mixing of the components listed in this example.

5 g Acetone 2.5 g Compound 1 in Table 1 2.5 g Hydroxyethylmethacrylate 0.01 g Camphoquinone 0.025 g DASA
Example 7 As a control, a preparation containing 4-MET is produced for use as an adhesive by intensive mixing of the following components:

5 g Acetone 5 g 4-MET

0.01 g Camphoquinone 0.025 g DASA

The effectiveness of the adhesives was tested by determining the shear bond strength on enamel and dentine, and by a microscopic analysis of the margins of cylindrical dentine cavities filled with a conventional composite filling TM
material (Pekafill by Bayer), after conditioning the dentine and applying the adhesive. The test was conducted with human teeth which had been kept in a lo chloramine solution for a maximum of 3 months after extraction. Prior to using the teeth, they were thoroughly cleaned under running water and then stored in a physiological sodium chloride solution for a minimum of three days and a nlaximum of ten days.
Shear Bond Strength On the day before the teeth were used in the bonding test, they were individually embedded, lying on an approximal surface, in epoxy resin (LekuthermTMX20, hardener T3) in cylindrical rubber moulds measurinq 25 mm in diameter and 12 mm in height. By wet-grinding the teeth with SiC paper (#240, #320, #400 and finally #600), a sufficiently large enamel surface or a peripheral deritine surface is laid bare, to which a plastic cylinder vaith a 3.5 mm diameter can be bonded. After rinsing with deionized water and drying in TM
an airstream, Gluma CPS conditionirig gel (20 a H3P04) is applied and carefully rinsed off 30 seconds later with water spray. Then the conditioned tooth surface is exposed very briefly to a weak airstream to remove the water from the surface (moist technique!). Apply the adhesive thinly with a brush, evaporate the solvent by careful blowing with compressed air. Repeat the application and evaporation TM
twice before irradiating for 20 seconds with the Translux CL
light emitter. Use a clamping devi_ce to clamp the pretreated sample under a cylindrical teflon form (3.5 mrn in diameter, 1 mm high) divided in hal.f. Apply the filling material with an injector, cover the form filled with excess with a translucent strip and irradiate for 60 seconds with TM
the Translux CL light emitter. Remove the teflon form immediately and store the sample in water at 37 C for 24 hours before introducing a shear load. To do this, place the cylindrical sample in a universal test apparatus, and with a plunger, apply a shear load parallel to and very close to the ground tooth surface at a rate of 1 mm/minute, until the cylinder is separated from the tooth. The shear bond strength (stated in MPa) equals the quotient of breaking force and bonding area. Examine the localization of the fracture under the stereo microscope (magnification factor of 60) and identify it as an adhesive or cohesive failure.

Results Shear bond strength on dentine (MPa) Preparation according to Example 6 11.7 0.4 Preparation according to Example 7 7.2 0.9 (Control) Only with the preparation according to Example 6 was the fracture near the marginal surface in the plastic (cohesive failure). The preparation according to Example 7 (the control) showed adhesive failure.

Shear bond strength on enamel (MPa) Preparation according to Example 6 20.1 1.5 Preparation according to Example 7 8.3 2.4 (Control) Only with the preparation according to Example 6 was the fracture deep within the enamel. The preparation according to Example 7 (the control) showed adhesive failure.

This confirms that only when the preparation according to the invention is used the bond between the substrates is stronger than the cohesive strength of either plastic or enamel. This confirms the effectiveness of the preparations according to the invention.
Microscopic Analysis of Cavity Margins To determine the adaptation of the cavity margins, wet-grind the extracted premolars or molars on the approximal surface with SiC paper (#600) until a sufficiently large dentine surface is exposed, into which a cylindrical cavity (3 mm in diameter, c. 1.5 mm deep) can be prepared. Form the cavity with a medium grit diamond drill, using a high-speed contra-angle, cooling with water. After careful cleaning with water, condition the surface and apply the adhesive as described above, before applying the Pekafill composite, covering with a strip, and irradiating for 60 seconds with the Translux CL light emitter. Immediately after polymerization, store the teeth for 10-15 minutes in water at room temperature before removing the excess filling material by means of careful wet-grinding with SiC paper (#600 and #4000) and exposing the cavity margin. Then inspect the cavity margin under the direct-light microscope (magnification factor of 500). If the filling material has become detached, measure the maximum gap width with an ocular micrometer and record it in m. Carry out the microscopic inspection within a maximum of 5 minutes before gaps may occur as a result of drying.

Results The preparation according to Example 6 proved to be very effective. No marginal clefts were found, and the adaptation of the cavity margins was perfect. Bonding to dentine occurred through the formation of a hybrid layer, which, as with the preceding conditioning, shows a thickness of 10-14 m. The control (Example 7-), on the other hand, shows that the filling material became detached, forming a marginal cleft of 7 m.

Example 8 Production of admixing liquids for glass ionomer cement Admixing liquids for light-hardening glass ionomer cement were produced by mixing the following components:

Components A B C D
1.3-Glycerol 40 35 35 45 dimethacrylate [o]

HEMA* [ o] 39 29 34 44 Compound 2 in Table 1[o] 10 25 15 -Water [%] 10 10 15 10 Camphoquinone [o] 0.45 0.45 0.45 0.45 DASA [X] 0.45 0.45 0.45 0.45 Ionol (stabilizer) 0.10 0.10 0.10 0.10 }Hydroxyethylmethacrylate In addition, a powdery mixture was produced of the following:

a) 47o glass ionomer powder of SiOZ 35.9o by weight A1203 22.5% by weight Na3AIF6 9% by weight AIF3 6.6% by weight AIPO4 5o by weight CaF2 21% by weight b) 4796 barium-containing GM 27884 dental glass (by Schott) , dso c. 1.3 m c) 6% AerosiL VP-R 711 (by Degussa).

Mix three parts of the powdery mixture with one part of the admixture liquids A-D and irradiate for 60 seconds with the Translux CL light emitter.

With the method described in Example 5 for determining inhibition, the thickness of the inhibition layers is calculated as follows:

Admixture liquid Compound 2 in Table Inhibition layer 1 (o) (E. m) A 10 2.9 B 25 1.5 C 15 2.81 D - 12.6 Only the admixture liquids with the compound according to the invention show good light hardening with a significant reduction in the thickness of the inhibition layer.

Claims (11)

CLAIMS:

1. A polymerizable (meth)acrylic ester of an aromatic carboxylic acid or a carboxylic acid anhydride derivative containing cyclic carbonate groups, which is a compound selected from the group consisting of:

2. A formulation comprising one or more suitable solvents and one or more polymerizable (meth)acrylic esters as defined in Claim 1.

3. A formulation according to Claim 2, characterized in that the formulation contains, as a photopolymerization initiator, a free radical former selected from the group consisting of mono-carbonyl compounds and di-carbonyl compounds.

4. A formulation according to Claim 3, characterized in that the photopolymerization initiator is camphorquinone.

5. A formulation according to Claim 3 or 4, characterized in that the formulation additionally contain a co-activator.

6. A formulation according to Claim 5, characterized in that the co-activator is an amine.

7. A formulation according to Claim 5, characterized in that the co-activator is dimethylaminobenzenesulphonamide.

8. Use of the formulation according to any one of Claims 2 to 7 as an adhesive.

9. Use of the formulation according to any one of Claims 2 to 7 in dental technology.

10. Use of the formulation according to any one of Claims 2 to 7 as a mixing liquid for glass ionomer cement.

11. Use of the formulation according to any one of Claims 2 to 7 in bone cement.