Note: Descriptions are shown in the official language in which they were submitted.
2199 624
2
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
2199624
3
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
4-MET 4-META
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
CA 02199624 2007-05-25
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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,
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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:
O-CH2 CH2
CHZ
I CH3 CH2 C-CHZ O-CHZ CH2
-CHZ CH-CH2 ,
CH 2 O -CHZ CH2
I 1
CH2 i CH 2
HO-CH2--C-CHz -CHZ C-CHZ
CH2 CH 2 O-CHZ CH2
CH2
-CH2 CHZ O-CHZ C-CH2 O-CHZ CHZ
CH2
I or
O-CHZ CHZ H2 HZ
-CHZ C-CHZ-O-CHZ C-CHZ CH2 ~ HZ
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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.
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Table 1
Carboxylic Acids and Carboxyanhydrides According to the
Invention
No. Formula No. Formula
0 2 0
0 0 0
o ~o o 0
~-o o oH ~-o ~o
O~ { Oy O OH O_ 1 OO O
~ \/
~\/ 0 0 y
O 0
3 0 4 O
o ~o 0 0 0 p o 0
~O O OH ~p ~O
O O OH p~Oyp O y O 0
O 0
0 6 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 ~
0 0
o p o O O O
O
0
a 0 O O
~ O
0 pO o a
a
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No. Formula No. Formula
9 10
~ 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
~
0
p ~
0/-O
11 12
~ 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
13 14
0 o
0 ~ 0
O H O~ ~ ~11 Oy OH y
O 0 0 ~
15 16
o a o
pH \\ O 0
/\ O
O~\ >-'O 0
l-0 ~O ol- ~--0 a
O~OyO \ / OH OyO
O 0
Q
0
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No. Formula No. Formula
17 18
= w, ~ 0 0
O
x o O0
~ 'r \ol o ~p~ ' O
0 Ol 0
\
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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,
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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.
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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
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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
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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.
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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:
2199624
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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
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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
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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
2199624
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(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.
2199624
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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.
2199624
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(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
2199624
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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
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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
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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
CA 02199624 2007-05-25
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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
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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.
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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:
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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).
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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.
