DENTAL MATERIAL WITH ALUMOORGANOPOLYSILOXANE FILLER

PRODUIT DENTAIRE COMPRENANT DU MATERIEL D'OBTURATION A BASE D'ALUMOORGANOPOLYSILOXANE

English Abstract

The present invention relates to a paste-like dental
material consisting of a polymerizable binding agent and a
finely divided filler that is based on special
organopolysiloxane compounds that contain aluminum and which
can be hardened in the presence of an initiator to form a
highly polishable substance, and to different applications of
the material for dental purposes.

French Abstract

L'invention porte sur un produit dentaire de type pâte, constitué d'un liant polymérisable et d'une charge finement divisée à base d'organopoly-siloxanes spéciaux renfermant de l'aluminum et pouvant être durcis en présence d'un initiateur pour former une substance facilement polissable, et servir dans différentes applications comme matériaux dentaires.

Claims

The embodiments of the invention in which an exclusive
property or privilege is claimed are defined as follows:
1. Paste-form dental material which, in the presence
of an initiator, is curable to a mass polishable to a high
gloss, the material comprising a polymerisable organic
binder and an Al-containing organopolysiloxane as the
filler which comprises units of the formula
<IMG> (I)
and units of the formula
<IMG> (II)
wherein R1 stands for a linear or branched alkyl group
bonded with an acrylate or methacrylate radical and having
1 to 6 C atoms, or for a linear, optionally branched,
unsaturated hydrocarbon radical having 2 to 8 C atoms and a
single olefinic bond, or for a cyclic unsaturated
hydrocarbon radical having 5 to 8 C atoms and a single
olefinic bond, or for a linear, optionally branched, alkyl
group having 1 to 8 C atoms, a cycloalkylene group having 5

to 8 C atoms, a phenyl group or an alkylaryl group, and/or
units of the formula
<IMG> (III)
in which R2 represents a methyl, ethyl, propyl or phenyl
group,
and there are present, in each of the compositions, units
of the formula
<IMG> or <IMG> (IV)
in which R3 is a linear or branched alkyl group having 1 to
5 C atoms or a phenyl group,
and the free valences of the oxygen atoms bonded to the
silicon atoms and aluminum atoms in the case of the units
(I), (II) and/or (III) and (IV) are, as in the case of
heterosiloxane skeletons, satisfied by a silicon atom of a
unit which is the same or different or by an aluminum atom,
wherein the ratio of the silicon atoms from the units of
the formula (I) to the sum of the silicon atoms of the
units (II) and (III) is from 3 : 1 to 100 : 1, and the
ratio of the sum of the silicon atoms from the units (I),
(II) and (III) to the aluminum atoms from the units (IV) is
from 2 : 1 to 200 : 1,

characterised in that the filler contained therein is
obtainable in the form of a random copolycondensate in that
an alkoxysilane of the general formula
Si(OR4)4 (V)
and an alkoxysilane of the general formula
R1 - Si(OR4)3 (VI)
in which R1 denotes the same as in formula (II),
and/or an alkoxysilane of the general formula
(R2)2Si(OR4)2 (VII)
in which R2 denotes the same as in formula (III) and an
aluminum compound of the general formula
AI(OR4)3 or AIR3(OR4)2 (VIII)
in which R3 denotes the same as in formula (IV), wherein R4
stands for a linear or branched alkyl group having 1 to 5 C
atoms,
are dissolved in a solvent which is largely water-miscible
but dissolves the compounds according to the formulae (V),
(VI), (VII) and (VIII), the reaction mixture is then

precondensed in the presence of an acid, basic or
metal-containing catalyst, with stirring, at a specific
temperature within the range from room temperature to
200°C, hydrolysis and complete polycondensation are
performed by the addition of optionally acid- or
base-containing water, and the solid formed is stirred,
optionally after the addition of further solvent or water,
for a further 1 to 6 hours at from 60 to 200°C, at standard
pressure or at a pressure which corresponds to the sum of
the partial pressures at the respective temperature, the
organopolysiloxane formed is then post-treated, optionally
after changing the medium and/or pH, for a further 1 hour
to 5 days at from 60 to 250°C in the liquid phase, and is
then separated from the liquid phase using current
techniques, is optionally washed, is dried at from room
temperature to 200°C, optionally in a protective gas
atmosphere or under vacuum, is then optionally tempered for
from 1 to 100 hours at temperatures of from 150 to 250°C in
a protective gas atmosphere or under vacuum, is optionally
ground and/or classified,
wherein, before or after one of the steps comprising
drying, tempering, grinding, classifying, the
organopolysiloxane separated from the liquid phase and
optionally washed, is treated in water, a water/alcohol
mixture or pure alcohol, in the presence of an acid or
basic catalyst for a period of from 1 hour to 5 days at

temperatures of from 60 to 250°C at a pressure which
corresponds to the sum of the partial pressures at the
respective temperature, and, before further working-up, is
washed until no acid or alkali remains.
2. The dental material according to Claim 1, in
which said unsaturated hydrocarbon radical having 2 to 8 C
atoms has a single olefinic bond in the end position.
3. The dental material according to Claim 1 or 2, in
which said organopolysiloxane separated from the liquid
phase is treated in water, a water/alcohol mixture or pure
alcohol in the presence of ammonia or alkali metal or
alkaline-earth metal oxides or hydroxides.
4. Dental material according to Claim 1, 2 or 3,
characterised in that the filler thereof is obtainable in
that hydrolysis and condensation are performed in methanol,
ethanol, n- and i-propanol, n- and i-butanol and/or
n-pentanol.
5. Dental material according to any one of Claims 1
to 4, characterised in that the filler thereof is
obtainable in that the monomer components according to the
formulae (V), (VI) and/or (VII) and (VIII) are
precondensed, with or without the use of a solvent which

dissolves the starting substances, in the presence of a
largely anhydrous acid or base for a period of from 5
minutes to 5 days at from room temperature to 200°C.
6. Dental material according to any one of Claims 1
to 4, characterised in that the filler thereof is
obtainable in the form of a block copolycondensate, in that
all the monomer components according to the formulae (V),
(VI) and/or (VII) and (VIII), in each case independently of
one another, or in a combination of 2 or at the most 3, are
precondensed in the presence of an anhydrous acid or base
for a period of from 5 minutes to 5 days at from room
temperature to 200°C, with or without the use of a solvent
which dissolves the starting substances, the condensates
obtained are combined and are then precondensed again
together for a period of from 5 minutes to 2 days at from
room temperature to 200°C, and the hydrolysis and complete
polycondensation according to Claim 1 are performed
following the addition of optionally acid- or
base-containing further solvent.
7. Dental material according to any one of Claims 1
to 4, characterised in that the filler thereof is
obtainable in the form of a mixed copolycondensate, in that
a minimum of one but a maximum of 3 monomers of the monomer
components according to the formulae (V), (VI) and/or (VII)

and (VIII), independently of one another or in combination,
are precondensed in the presence of a largely anhydrous
acid or base for a period of from 5 minutes to 5 days at
from room temperature to 200°C, with or without the use of
a solvent which dissolves the starting substances, the
precondensate or precondensates obtained and at least one
component which has not been precondensed are combined, the
combined components are then precondensed again for a
period of from 5 minutes to 2 days at from room temperature
to 200°C, and the hydrolysis and complete polycondensation
according to Claim 1 are performed following the addition
of optionally acid- or base-containing water and optionally
further solvent.
8. Dental material according to Claim 5, 6 or 7, in
which said solvent which dissolves the starting substances
is a linear or branched alcohol corresponding to the alkoxy
groups and having 1 to 5 C atoms.
9. Dental material according to any one of Claims 1
to 8, characterised in that the filler is present in
relation to the units (I) to (IV) as a random
copolycondensate, a block copolycondensate or a mixture of
the latter forms.

10. Dental material according to any one of Claims 1
to 9, characterised in that R1 in formula (II) stands for
the group
<IMG>
11. Dental material according to any one of Claims 1
to 10, characterised in that as the filler an
organopolysiloxane is used which comprises units of the
formula (I) and units of the formula (II) having the
composition
<IMG>
as well as units of formula (IV), the molar ratio of the
units in formula (I) to the units of formula (II) being
3 : 1 to 100 : 1, and the ratio of the sums of the silicon
atoms in units (I) and (II) to the aluminum atoms of units
(IV) being 2 : 1 to 200 : 1.
12. Dental material according to any one of Claims 1
to 10, characterized in that as the filler an
organopolysiloxane is used which comprises units of the
formula (I) and units of the formula (III) composed of
<IMG>

as well as units of the formula (IV), the molar ratio of
the units in formula (I) to the units of formula (III)
being 3 : 1 to 100 : 1, and the ratio of the sums of the
silicon atoms from the units (I) and (II) to the aluminum
atoms of units (IV) amounting to 2 : 1 to 200 : 1.
13. Dental material according to any one of claims 1
to 12, wherein the filler has a specific surface area of 10
to 250 m2/g, and a particle size of 0.01 microns to 100
microns.
14. Dental material according to any one of claims 1
to 12, wherein the filler has a specific surface area of 30
to 200 m2/g, and a particle size of 0.01 microns to 30
microns.
15. The use of dental material as defined in any one
of claims 1 to 14, to make dental fillings, in-lays,
blends, dental seals, coatings to protect the surfaces of
the teeth, crowns, bridges, dental protheses, artificial
teeth, adhesives for securing in-lays, crowns and bridges,
and to build up broken teeth.

Description

2 ~ 2 ~
The present invention relates to a paste-like dental material
that consists of a polymerizable organic binding agent and a
finely-divided filler, which can be hardened to a lustrous
polishable mass in the presence of an initiator. The material
contains at least one polymerizable methacrylate as binding
agent and an optionally silanizable, new type of filler based
on polysiloxanes that contain aluminum. In addition,
initiators that trigger the polymerization process, additional
fillers such as finely-grounded glasses, highly dispersed
silicic acid, or preformed polymerizates, pigments, and
stabilizers can also be contained in it. Other additives such
as softeners or substances to improve impact resistance can
also be used.
The term "dental material" includes, for example, filling
materials that are used to manage caries-type defects or other
dental defects in the oral cavity, in-lays, crown and bridge
materials, blending agents, sealing and protective-coating
substances, plastic attachment materials used to secure in-
lays or crowns and bridges, materials used to build up broken
teeth, materials for the production of protheses and
substances used to produce dentures.
Conventional dental substances of the above type contain at
least one monomer ester of methacrylic acid, but mostly a
mixture of a plurality of such esters. Suitable
monofunctional esters of methacrylic acid are, for example,
methylmethacrylate, ethylmethacrylate, isopropylmethacrylate,
n-hexylmethacrylate, and 2-hydroxyethylmethacrylate.
Recently, multi-functional esters of methacrylic acid with
higher molecular weights have frequently been used; these are,
for example, ethyleneglycoldimethacrylate, butandiol-1,~-
dimeth-acrylate, triethyleneglycoldimethacrylate, dodecandiol-
1,12-dimethacrylate, decandiol-1,10-dimethacrylate, 2,2-bis-
[p(~-methacryloxy-~-hydroxypropoxy)-phenyl]-propane the diaduct
of hydroxymethylmethacrylate, and trimethylhexamethylene-
diisocyanate, the diaduct of hydroxymethylmethacrylate and

2~7~ 2~
isophorondiisocyanate, trimethylolpropanetrimethacrylate,
pentaerythrittrimethacrylate, pentaerythrittetramethacrylate,
and 2,2-bis[p(~-hydroxy-ethoxy)-phenyl]-propanedimethacrylate
(bis-GMA).
Depending on the purpose for which they are to be used,
materials for dental applications can be hardened in various
ways. Tooth-filling materials can be either photo-hardening
or else self-hardening (autopolymerizing) materials. The
photo-hardening materials contain photo-initiators such as
benzoinalkylether, benzilmonoketales, acylphosphinoxides, or
aliphatic and aromatic 1,2-diketo compounds such as, for
example, camphor chinon, as well as polymerization
accelerators such as aliphatic or aromatic tertiary amines
(e.g., N,N-dimethyl~p-toluidine triethanolamine) or organic
phosphites, and become hard when irradiated with ultra-violet
or invisible light.
As a rule, the self-hardening materials consist of a catalyst
paste and a base paste, each of which contains a component
part of a redox system, and which polymerize when the two
components are mixed. The one component part of the redox
system is mostly a peroxide, such as, for example,
dibenzoylperoxide, and the other is mostly a tertiary aromatic
amine, such as, for example, N,N'-dimethyl~p-toluidine.
Other dental materials, such as plastics for protheses or
plastic materials for the production of artificial teeth can
be polymerized by the action of heat. Here, as a rule,
peroxides such as dibenzoylperoxide, dilaurylperoxide, or
bis(2,9-dichlor-benzoylperoxide) are used as initiators.
As a rule, dental materials also contain pigments which, added
in small quantities, serve to match the colour of the dental
materials to the various shades of natural teeth. ~uitable
pi~ments are, for example, iron oxide black, iron oxide red,
iron oxide yellow, iron oxide brown, cadmium yellow, and
cadmium orange, zinc oxide, and titanium dioxide.

2~7~ 2~
Furthermore, most dental materials contain organic or
inorganic fillers. These are added in order to reduce the
amount by which the volume of the plastic materials shrinks on
polymerization. As an example, pure monomer methylmethacrylate
shrinks by approximately 20%-volume during polymerization. By
adding approximately 60 parts by weight of solid
methylmethacrylate-pearl polymerizate, this shrinkage can be
reduced to approximately 5 - 7%-volume (DE-PS 24 03 211).
Other organic fillers are obtained in that one produces a
polymerizate that consists essentially of esters of
methacrylic acid and is either cross-linked or not.
Optionally, this polymerizate can contain surface-treated
fillers. If it is produced as a polymerizate, it can be added
to the dental material in this form; on the other hand, if it
is produced in compact form by substance polymerization, it
must first be ground to form a so-called dendritic
polymeriz'ate before it is introduced into the dental material.
In addition to the above-discussed pearl and dendritic
polymerizates, frequently used, pre-formed polymerizates are
homopolymerizates of the methacrylic acid methylester or,
preferably not cross-linked, copolymerizates of the
methacrylic acid methylester with a small quantity of esters
of methacrylic acid or acrylic acid wlth 2 to 12 carbon atoms
in the alcohol component, more expediently in the form of a
pearl polymerizate. Other suitable poly~lerizates are non-
cross-linked products based on polyurethanes, polycarbonates,
polyesters, and polyethers.
Examples of inorganic fillers are ground glasses or quartz
with mean particle sizes between approximately 1 and 10
microns, as well as highly dispersed SiO2 with average
particle sizes between approximately 10 and 400 nm.
In the case oE the glasses, these are preferably aluminum
silicate glasses that can be doped with barium, strontium, or
rare earths (DE-PS 24 58 380).

2 ~
~ith respect to the finely-ground quartz or the finely-ground
glasses, as well as the highly dispersed SiO2, it should be
noted that the inorganic filler is, as a rule, silanlzed prior
to being mixed with the monomers, this being done in order to
ensure a b~tter bond on the organic matrix. To this end, the
inorganic fillers are coated with silane coupling agents,
which mostly have a polymerizable double bond for reaction
with the monomer esters of the methacrylic acid.
Examples of suitable silane coupling agents are
vinyltrichlorsilane, tris-(2-methoxyethoxy)-vinylsilane, tris-
(acetoxy)-vinylsilane, and 3-methacryloyloxy-
propyltrimethoxysilane.
The above-discussed, recently used monomers of high molecular
weight also reduce the shrinkage that occurs on
polymerization. Up to 85%-wt of these inert inorganic and
finely-ground glasses or organic fillers or mixtures of these
are added to these monomers, when it is possible to achieve a
further reduction of shrinkage to approximately 1% by volume.
The inorganic fillers work not only to reduce shrinkage on
polymerization but they also bring about a considerable
strengthening of the organic polymer structure.
This strengthening can be perceived in an improvement of
mechanical properties, as well as increased resistance to wear
(R. Janda, Quintessence 39, 1067, 1243, 1393 (1988)). Good
mechanical properties and a high level of resistance to wear
are important demands that are made on a dental substance
intended to be a permanent replacement for hard dentitian
substance that has been lost.
In addition to the strengthening properties, the fillers must
also be equal to other material parameters. In this
connection, one important parameter is polishability.
Polishability to a high lustre is of considerable importance
for filling materials and the materials used for crowns and
hridges, for at least two reasons:

2 ~ 7 l~
For esthetic reasons, a lustrous and completely homogenous
surface is required for filling materials so that the
filling cannot be distinguished from the surrounding,
absolute]y smooth and natural material that makes up the
tooth. Furthermore, this highly lustrous filling surface
must retain its character for a very long time.
A highly polished filling surface is also important so that
plaque and other discolouring media are unable to find any
mechanical anchor points.
.
Now, it has been shown that although the above-described
finely-ground quartz or glass fillers have good reinforcing
qualities, they cannot satisfy ~P~n~s that are made with
regard to their polishabilityO For this reason, attempts have
been made to grind these inorganic fillers to an even finer
degree in order to obtain a more homogenous surface. However,
limits are imposed on physical grinding methods so that mean
grain sizes below 1 micron are still extremely difficult to
produce.
When highly dispersed silicic acid (median particle size 10 -
400 nm) is used as a filler in dental substances (DE-PS 24 03
211), it was most surprisingly, shown that with these fillers
it was possible to achieve considerably improved
polishability. Disadvantages associated with this highly
dispersed silicic acid are caused by its marked thickening
effect, so that today, as a rule, filling cannot be achieved
to more than 52%-wt, unless one is satisfied with inadequate
finishing properties.
Furthermore, materials that are filled with highly dispersed
silicic acid are clearly of lower strength and hardness than
those that are filled with quartz or finely ground glasses.
DE-OS 39 13 250 A1 and DE-OS 39 13 252 A1, and DE-PS 39 03 407
describe new filling materials which, used in appropriate
dental materials, ensure good mechanical properties and

2~7~2~
polishability at ~he same ~ime. For this reason, these
products already display thoroughly satisfactory properties in
this regard. A disadvantage found in these systems is,
however, that they frequently suffer from a lack of
transparency. For this reason, the required colour match is
difficult to achieve in such cases and photo-hardening, which
is practiced pre~omin~ntly in these cases, can only be
accomplished to an unsatisfactory degree.
Now it has been found that the incorporàtion of aluminum oxide
units in the siloxane structure described in the patent
applications cited heretofore leads to a clear improvement of
the transparency of corresponding dental materials. A
prerequisite for this is the observance of a specific
procedure during the production of these fillers, which is
also an object of the present invention. In this connection,
an important feature is precondensation of the monomer
components under water-free conditions, in the presence of an
acid or base condensation catalyst, this precondensation
preceding the actual total condensation.
It is an object of the invention to prepare new photo-
hardening, thermo-hardening, or self-hardening dental
materials from a polymerizable organic bonding agent and a
finely divided filler which, on the one hand, can be polished
to a high lustre and which thus satisfies the esthetic demands
imposed on dental material and, on the other, possess better
physical properties than those polishable dental materials
that represent the prior art and, in addition, are always
sufficiently transparent.
This problem has been solved in that a new paste-like dental
material which can be hardened from a polymerizable organic
binding agent and a finely divided filler in the presence of
an initiator to form a substance that can be polished to a
high lustre; this material contains an organopolysiloxane that
contains aluminum as a filler and units of the formula

~7l~2~
I
- O-Si-O - (I)
1~
and units of the formula
- O-Si-O - (II)
O
wherein Rl stands for a linear, optionally branched, alkyl
group with 1 to 6 carbon atoms connected with an acrylate or
methacrylate radical, or for a simple olefin unsaturated,
preferably end position unsaturated linear, optionally
branched, hydrocarbon radical with 2 to 8 carbon atoms, or for
a cyclic, simply olefin~unsaturated hydrocarbon radical with 5
to 8 carbon atoms,~or for:a linear, optionally branched, alkyl
group with:1 to~8 carbon atoms, a phenyl group, a - :
cycloalkylene group with 5 to 8 carbon atoms, or an alXylaryl
group, and/or unlts of formula
R2
--O-Si-O - (III)
R2
wherein R2 stands for a methyl, ethyl, propyl, or phenyl group
and--in each of the compositions--has units of the formula
O R3
- O-Al or _ o-~l (IV)
O O

2~7~2~
wherein R3 is a linear or branched alkyl group with 1 to 5
carbon atoms or a phenyl group, and the free valences o~ the
oxygen atoms that are bonded to the silicon or aluminum atoms
are saturated by a silicon atom of an i~entical or a different
unit or by an aluminum atom in units (I), (II) and/or (III) as
well as in (IV), as in heterosiloxane structures; the ratio of-
the silicon atoms from units of formula (I) to the sum of the
silicon atoms of units (II) and (III) amounts to 3:1 to 100:1,
and the ratio of the sum of the silicon atoms of units (I),
(II), and (III) to the aluminum atoms of the units (IV)
amounts to 2:1 to 200:1.
The units as in formulas (I) to (IV~ can naturally be present
in forms that are different from one another, i.e., they can
be present in the form of a statistical copolycondensate, or
in the form of a block copolycondensate, or in the form of a
so-called mixed copolycondensate. ~ccording to the present
invention, the fillers of the new dental materials can be
present in each of the above forms in the relation to the
units as in formulas (I) to (IV), and in mixtures of these.
This means that in the case of a pure statistical
copolycondensate that contains units of formula (I), (II),
and/or (III) as well as (IV) a purely statistical distribution
of the components corresponding to the molar relations of the
starting products will exist.
In the case of a so-called block copolycondensate, the
formation of blocks of equal units as in formula (I) and (II)
and/or (III) as well as tIV) will take place. Finally, a so-
called mixed copolycondensate has both the structures of a
statistical copolycondensate as well as of a block
copolycondensate.
The fillers according to the present invention are used in
dental substances at quantities of 20 to 90~-wt, and
preferably 25 to 80~wt. Naturally, the fillers according to
the present invention can also be used in combination with

2 ~ 2 ~
other fillers, such as, for example, silicic acid or finely
ground glasses. The unsaturated organic radical R1 that can
optionally be present on the units as in formula (II) can
serve mainly to ensure a so]id bonding of the polysiloxane
filler on the polymer matrix that is subsequently generated
from the polymerizable organic bonding agent.
For this reason, organic radicals R1 in which a double bond is
easily accessable sterically and is also relatively easy to
polymerize are particularly suitable for this reason. This
applies, in particular, to the group
O CH
Il 1 3
t CH2)3 0 C C CH2
because its particularly easy polymerizability is known and,
in addition and as a rule, in the case of the polymer matrix
in which the filler is to be incorporated, it is usually a
methacrylate system both for linear hydrocarbon radicals with
double bonds at the end positions such as, for example, the
vinyl, butenyl, or octenyl radical. Cyclic hydrocarbon
radicals with polymerizable double bonds are also suitable,
however. In many instances, R1 can however also be an organic
radical without any double bonds, which is similarly cited
under formula (II) in claim 1.
A particularly advantageous composition for the filler
substance, which is distinguished by simple realization and
mainly by the industrial availability of the starting
materials, provides that an organopolysiloxane is used as a
filler, this consisting only of units of formula (I) and the
special units of formula (II)
O O CH3
o-SitCH2)3 0 C C CH2
~l

~7~
as well as of units of formula (IV), when the molar ratio of
the units of formula (I) to the units of formula (II) amounts
to 3:1 to 100:1, and the ratio of the sums of the silicon
atoms of units (I) and (II) to the aluminum atoms of units
(IV) amounts to 2:1 to 200:1. A filler of this kind is, in
principle, distinguished in that it no longer has to be
silanized in order to be incorporated into the methacrylate
matrix, i.e., it does not have to be treated with a methacryl
silane, after this methacryl group is present, homogenously
divided, in the filler.
However, this does not rule out the fact that in individual
cases, with respect to a further hydrophobization with further
strengthening of the bond between the organopolysiloxane
filler and the organic polymer matrix, silanization of the
filler will be additionally undertaken.
During development of the present invention, it was shown that
very good mechanical properties and polishability of the
dental material can also be achieved if the organosiloxane
filler that is used contains no unsaturated radicals R1, but
only saturated radicals R1.
This applies both for fillers that contain units as in
formulas (I), (II), and (III), and (IV), as well as for those
fillers that contain only units as in formula (I) and (II).
Such organopolysiloxane fillers, which are not double bond
functional, should be treated with a suitable organosilane
compound, preferably 3-methacryloyloxy-propyltrimethoxy or 3-
methacryloyloxypropyltriethoxysilane, before they are
incorporated into the organic polymer matrix.
This applies analogously to a filler composition according to
the present invention that is advantageous because of the
particular ease of availability of the starting materials,
which provides for the synthesis of the polysiloxane from
units of formula (I) and the special units of formula (III)
-- 10 --

2~7~
CIH3
--o-si -o
CH3
as well as from units of formula (IV), the molar ratio of the
units as in formula (I) to the units of formula (III),
amounting to 3:1 to 100:1, and the ratio of the sums of the
silicon atoms from the units (I) and (II) to the aluminum
atoms of units (IV) amounting to 2:1 to 200:1.
Furthermore, it is relevant for all the embodiments according
to the present invention that are claimed that the proportion
of aluminum that is necessary in respect of the desired
transparency of the dental materials produced with the fillers
is to be so selected that the ratio of the sums of the silicon
atoms from formulas (I), (II), and (III) to the aluminum atoms
of units (IV) amounts to 2:1 to 200:1.
.
The monomer component blocks of the fillers according to the
present inv~ntion are compounds known in principle, for
example, Si(OC2Hs)4 as monomer component blocks for a unit of
formula (I~, a compound
O CH
ll l 3
(H3Co)3si- (CH2)3 O-c-c=cH2 or
(H3Co)3Si CH2CH2CH3
as monomer component blocks for units of formula (II) and a
compound (H3C)2Si(OC2Hs)2 as a monomer component block for
units of formula (III) as well as a compound Al(OC2Hs)3 as a
monomer component block for units of formula (IV).
The compositions of the dental fillers that can be produced
from these according to the present invention can be
described, for example, by formulas for a particular polymer
unit such as

2~7~
CH3
SiO2-CH~ C-C-~-(CH2)3Si~3/2 ~ (CH3)2si~2/2 3/2
o
10 SiO2 C3H7SiO3/2 ~ (H5C2)2SiO2/2 ~ 2 A1~3/2
Si~2 ~ (H3C)2sio2/2 ~ 6 ~1~3/2 or
CH3
Si~2 ~ CH~C-C-O-(CH2)3SiO3/2 ~10AlO3/2
O
Units af formula (II) according to claim 4 and units of
formula (III) according to claim 5 aré to be preferred,
amongst reasons, because the corresponding monomers are
technically available products.
With respect to their physical properties, the fillers
composed according to the present invention are particularly
well suited for use in dental materials accarding to the
present inventian if they have a speciflc surface area of
'approximately 10 to 250 m2/g, preferably approximately 30 to
200 m2/g, and a particle size from 0.01 microns to 100
microns, and preferably 0.1 microns to 30 microns.
The fillers contained in the dental materials according to the
present invention can be obtained by various methods. One
production method that is aimed at achieving a statistical
copolycondensate provides that one dissolves an alkoxysilane
of the general formula ~
Si(oR4)4 (V)
and an alkoxysilane of general formula
R1 - Si(oR4)3 (VI)
- 12 -

2~7~ 2~
in which R1 is of the same value as in formula (~I3, and/or an
alkoxysilane of the general formula
(R2)2Si(OR~)2 (VII)
in which R2 is of the same value as in formula (III), as well
as an aluminum compound of general formula
Al~OR4)3 or AlR3(OR4)2 (VIII)
in which R3 is the same value as in formula (IV), wherein R4
stands for a linear or branched alkyl group with 1 to 5 carbon
atoms, in a solvent that is water miscible but which dissolves
the compounds as in ~ormula (V), (VI), (VII), as well as
(VIII), and then precondenses the reaction mixture in the
presence of a catalyst that is acid, base, or which contains
metal, while stirring at a specific temperature in the range
of room temperature to 200~C, then carries out hydrolysis and
complete polycondensation by the addition of water that
optionally contains acid or base and then stirs the solid that
is formed, optionally after the addition of additional solvent
or water, for a period of 1 hour to 6 hours at 60~C to 200~C,
at normal pressure or at a pressure that corresponds to the
partial pressures at the particular temperature in each
instance; the organopolysiloxane that is formed is then
retreated, optionally after the medium and/or the pH value has
been changed, for a further 1 hour to 5 days at 60~C to 250~C
in the liquid phase, and then separates this from the liquid
phase using available technology, optionally washes this,
dries it at room temperature to 200~C, optionally in an
atmosphere of protective gas or in a vacuum, then, optionally
tempers this for a period of 1 to 100 hours at temperatures
from 150~C to 250~C in an atmosphere of protective gas or in a
vacuum; it is then optionally ground andjor graded, when one
treats the organopolysiloxane that has been separated from the
li~uid phase and optionally washed, be~ore or after one of the
stages such as dryiny, tempering, grinding, grading in water,
a water/alcohol mixture or in pure alcohol, in the presence of
- 13 -

~7~2~
an acid or a base catalyst, preferably in the presence ofammonia or alkali or alkali o~ides or earth alkali hydroxides,
for a period that varies from 1 hour to 5 days at temperatures
from 60~C to 250~C at a pressure that corresponds to the
partial pressures at the particular temperature, and then
washes this until it is free of acid or lye before further
processing.
According to a preferred embodiment of the precondensation,
one proceeds such that the monomer components as in formula
(V), (VI), and/or (VII), and (VIII) are precondensed with or
without the use of a solvent that dissolves one of the
starting substances, preferably a linear or branched alcohol
that corresponds to the alkoxy groups, with 1 to 5 carbon
atoms, in the presence of a largely water-free acid or base,
for a period of 5 minutes to 5 days at room temperature to
200~C.
A typical acid catalyst is, for example, hydrochloric acid or
acetic acid or an alkylsulfonic acid or a Lewis acid, whereas,
for example, in addition to ammonia/ amines and other ~ewis
bases or alkali or earth alkali alcholates represent typical
base catalysts.
Precondensation is carried out under largely water-free
conditions with the help of these catalysts. When this is
done, equilibration with reference to the alkoxy groups at the
different monomer components as in formula (~) to (VIII) takes
place, to~ether with formation of oligomeres. Thus,
precondensation is a prerequisite in order to arri~e at a
homogenous gelling behaviour of the components as in formulas
(V) to (VIII), and to achieve a uniform polycondensate. This
aspect is particularly important in relation to the aluminum
components as in formula (VIII), because these display a
significantly greater amenity to hydrolysis and condensation
than the silane components (V) to (VII). In order that the
precondensation is not disrupted by premature and excessive
condensation of a component, the presence of water is
- 14 -

2~7~2~
undesirable, and so freedom from water is required.
Surprisingly, only fillers according to the present invention
that are produced in this way impart sufficient transparency
to dental materials and at the same time provide outstanding
mechanical properties and good polishability.
The duration of the precondensation and the reaction
temperature that is used will, as a rule, depend on the
reactivity of the monomer components as in formula (V) to
(VIII), this generally being higher in the case of aluminum
than it is in the case of the silicon. In the case of monomer
components (V), (VI), and (VIII), which contain silicon, the
reactivity will depend in particular on the groups R4 and the
substituents Rl or R2, respectively, such that a reduction in
reactivity occurs within the increasing size of the same.
The advantageous application properties of the new fillers can
be attributed to the acid or alkali temperature treatment
before or after drying, or in one of the optionally applied
treatment stages, since it is primarily a consolidation of the
polymer structure that is achieved because of this.
In principle, the corresponding halogenide compounds or
phenoxy compounds can be used as starting materials for the
process in place of the alkoxy compounds, although the use of
these entails no advantages but can, for example in the case
of the chlorides, cause difficulties because of the
hydrochloric acid that is liberated during hydrolysis.
Hydrolysis of the precondensates must be accomplished in a
largely water-miscible solvent that, however, dissolves the
starting materials. Preferably, alcohols which correspond to
the alkoxy groups in the monomer startin~ substances are used.
Especially suitable are methanol, ethanol, n- and i~propanol,
n-and i-butanol, and n-pentanol. Mixtures of such alcohols
can also be used as solvents during hydrolysis.
- 15 -

2 ~ 7 ~
Naturally, other polar solvents that are largely water-
miscible can be used in place of alcohols although for reasons
of process technology, this is not expedient on account of the
solvent mixture that results with the hydrolytically separated
alcohol.
It is preferred that hydrolysis be carried out with an excess
of water beyond the stoichiometrically necessary quantity.
The quantity of water that is required for hydrolysis depends
on the hydrQlysis rate of the precondensate such that as the
quantity of water increases, hydrolysis takes place more
rapidly, although an upper limit can be~imposed by segregation
and the formation of a two-phase system. -Fundamentally,
hydrolysis in an homogenous solution is preferred.
Because of the aspects cited above, the maximum quantity of
water by weight that is used will be the same as the total
quantity of silane monomers that is used.
The water that is used for hydrolysis can contain an organic
or inorganic acid or a base. The addition of acids or base
can, on the one hand, be made to neutralize the reaction
mixture after acidic or base precondensation, or to adjust an
optimal pH value during the gelling process. Thus, for
example, precondensation can be carried out under acidic
conditions and gelling can be carried out under base
conditions.
Polycondensation can be accomplished at various temperatures.
Polycondensation takes place most rapidly at higher
temperatures and so this is preferably carried out at
refluxing temperature or just below this. In principle,
hydrolysis and polycondensation can be carried out at higher
temperatures than reflux temperature, i.e., under pressure.
The reaction mixture may solidify to a solid mass during
polycondensation. ~or this reason, it is appropriate to add
- 16 -

2~7~2~
an appropriate quantity of solvent or water for purposes of
dilution.
In this connection, as a rule the solvent will be the same as
was used during hydrolysis of the silanes, i.e., a low alcohol
with 1 to 5 carbon atoms is preferred.
Naturally, dilution can be effected with water as an
alternative to dilution using a solvent. Whatever is used in
a particula~ case will also depend on which physical
properties the copolycondensate that is to be produced is to
have. This can also be influenced by the duration and
temperature of the secondary treatment in the liquid phase or
in dry form. In every case, a secondary reaction at a higher
temperature always leads to consolidation of the structure of
the polymer and to an improvement of its mechanical
properties.
Separation of the solid that has formed can be accomplished by
way of customary technology such as filtration, decantin~, or
centrifuging, or by distillin~ off the liquid phase. The
solid that has formed is preferably washed with the solvent
that is used for precipitation, or with water.
The dried or tempered product can be ground in conventlonal
apparatuses and graded into different grain-size fractions.
Depending on circumstances, one or ~he other of the processing
measures such as washing, drying, tempering, grinding, and
grading can be omitted, or else they can be carried out in a
different sequence.
Classification can also be carried out, for example, on
product that is damp, and optionally on previously dried or
tempered product~
Duration of the hydrolysis will depend on the amenity of the
precondensate to hydrolysis and on temperature. The rate of
hydrolysis will depend, in particular, on the alkoxy groups at

2 ~ 7 '~
the silicon position, the methoxy group hydrolyzing the most
rapidly, the process slowing down with increasing chain length
or with an increasing amount of branching.
Statistic copolycondensates are obtained according to claim 7.
So-called block copolycondensates are obtained using another
method as set out in claim 10; in these, formatlon of blocks
of equal units as in formula (I) and (II~ and/or (III), and
(IV) takes place. This procedure provides for the fact that
one precondenses the monomer components as in formula (V),
(VI), and/or (VII), and in (VIII), in each instance
independently of each other or in a combination of two or at
most three components in each instance, with or without using
one of the solvents that dissolve the starting substances,
preferably of a linear or branched alcohol with 1 to 5 carbon
atoms that corresponds to the alkoxy groups, in the presence
of a water-free acid or base, for a period of 5 minutes up to
5 days at room temperature to 200~C, then combines the
condensates so obtained and precondenses them together once
more for a period of 5 minutes up to 2 days at room
temperature to 200~C, and then, after the addition of water
that optionally contains acid or base and, optionally, after
the addition of extra solvent, one carries out hydrolysis and
complete polycondensation as described above with regard to
the statistical copolycondensates.
So-called mixed copolycondensates are obtained using another
method; in these, there is in part formation of blocks of
identical units as in formula (I) and III) and/or (III), and
(IV), in which, however, there is always at least one monomer
component that is not precondensed initially and at leas-t one
monomer component that is precondensed initially alone or in
combination with other components.
In order to prevent any differences in ~the yelling behaviour
of precondensed components and components that have not been

2~7~.25L;j
precondensed, joint precondensation will be rsquired once
again after they have been combined.
The procedure to obtain mixed copolycondensates provides that
of the monomer components as in formula (V), (VI) and/or
(VII), and (VIII), one precondenses at least one monomer, but
at most 3 monomers, independently of each other or in
combination with each other, with or without using a solvent
that dissolves the starting substances, preferably a linear or
branched alcohol with 1 to 5 carbon atoms that corresponds to
the alkoxy groups, in the presence of a largely water-free
acid or base, for a period from S minutes up to 5 days at room
temperature to 200~C, combines the precondensate so obtained,
or the precondensates so obtained, and at least one component
that has not been precondensed with each other, and then
precondenses the combined components for a period of 5 minutes
up to 2 days at room temperature to 200~C once again, and
then, after the addition of water that optionally contains
acid or base and, optionally, additional solvent, one carries
out hydrolysis and complete polycondensation using the two
methods described heretoforeO
The use of a condensation catalyst that contains metal for
precondensation is also possible in this variation of the
production procedure, and the further treatment of the
polycondensate that is formed follows the production processes
described heretofore.
As has been discussed above, the duration of the
precondensation will generally depend on the reactivity of the
monomer compone~ts and temperature.
The fillers for the new dental materials are characterized, in
particular, on the basis of the quantitative hydrolysis and
condensation yields and on the basis of elementary analysis.
There are no visual differences between the copolycondensates
that have been obtained by using the different production
procedures.
-- lg --

2~7~
Depending on treatment, the fillers according to the present
invention have weights per surface unit of 10 -to 250 m2/g,
preferably 30 to 200 m2~g. The desired particle diameters of
0.01 mi~rons to 100 microns can be achieved without any
problem by using available grinding techniques.
A further object of the present invention is the use of the
dental material according to the claims that are made for the
production of dental fillings, inlays, dental seals, coatings
applied to protect the surface of the teeth, crowns, blends,
bridges, dental protheses, artificial teeth, adhesives for the
attachment of inlays, crowns and bridges, and for building up
broken teeth.
The present invention is described in greater detail below on
the basis of the embodiments that are described.
I. Production of filler-~ accorcling to the present invention
Example 1
1379.8 g (6.62 mol) Si~oc2Hs)4, 54.8 g (0.22 mol) of
methacryloylo~ypropyltrimethoxysilane, and 54.4 g (0.22 mol)
of Al(0-sec.C4Hg)3 were mixed with 130 ml of 4n ethanolic
hydrochloric acid solution within a period of 10 minutes while
stirring. The mixture was heated to reflux temperature and
stirred at this temperature for a period of 1 hour. Then, 600
ml of ethanol were added to it and it was stirred for a
further period of 3 hours at this temperature. After cooling
to 50~C, 525 ml of 10% aqueous NH3 solution were added within
a period of 30 minutes. Shortly therea'fter the batch of the
homogenous solution began to gel. ~fter increasing the
stirring rate to 700 rpm, 750 ml of desalinated water were
added to the suspension that was formed. This was stirred for
a further period of 1 hour during refluxing, then cooled, and
the solids filt~red off. The solid was stirred into 500 ml of
5% ammonia solution. The suspension was stirred for a further
period of 24 hours in an autoclave at 150~C at the resulting
- 20 -

2 ~ 7 ~
pressure. The solid was filtered off, washed with water until
neutral, then dried for 24 hours at 120~C, and ground for 10
hours in a ball mill until the mean particle diameter lay in
the range of 15 microns.
443 g (99.0% of the theoretical) of a dèntal filler,
consisting of polymer units of the formula
CH2
C-C-o-(CH2)3SiO3/2 ~ 30 SiO2 3/2
o
were obtained. All elementary analyses were in keeping with
this composition.
Specific surface area: 127 m2/g
Example 2
950 g (4.56 mol) of Si(OC2Hs)4, 22.54 g (0.151 mol) of
(H3C)2Si(OC2Hs)2 and 224.65 g (0.912 mol) of Al(0-sec.C4Hg)3
were combined in a 3-litre glass vessel with a stirrer, a
reflux cooler, and an internal thermometer. 88 ml of 4n
ethanolic hydrochloric acid solution was added to the mixture
within 5 minutes, and stirred for 6 hours during refluxing.
Then, the mixture was cooled down to 50~C and mixed with 500
ml of ethanol and with ~20 ml of 10% aqueous NH3 solution.
This was stirred for a further period at 70~C, until gelling
began after 5 minutes. An extra 600 ml of water were added to
the gel that was forming for dilution. After a further reflux
phase lasting 1 hour, the batch was worked up as in Example 1,
when post-treatment of the solid that had been filtered off
was conducted in an autoclave in 500 ml of 2% NH3 solution.
328 g (99.5~ of the theoretical) of a dental filler,
consisting of polymer units of the formula
(H3C)2siO2/2 30 SiO2 ~ 6 Al03/2
- 21 -

~-7~
were obtained. Elementary analyses were in keeping with this
composition.
Specific surface area: 93 m2/g
Example 3
16.43 g (0.1 mol) of n-C3H7-Si(OCH3)3, 264.4 g (1.0 mol) of
Si~OC3H7)4, and 24.63 g tO.1 mol) of Al(OC4Hg)3 were each
mixed with 2 ml of acetic acid (10096) and each was stirred for
1 hour at 70~C. Then, the three precondensates were combined
in a 2-litre stirring flask with a KPG stirrer, a reflux
cooler, and an internal thermometer, and stirred for a further
1 hour at 70~C. The mixture was cooled down to 50~C and mixed
with 300 ml of isopropanol and then with 100 ml of 2% aqueous
ammonia solution and stirred at refluxing temperature until
gelling began. The gel that was forming was mixed with 300 ml
of water, stirred for a further 2 hours during refluxing, and
then processed further as in Example 1, with the exception
that the secondary treatment was carried out in an autoclave,
in 200 ml of NaOH solution at pH 10.
73.5 g (98.496 of the theoretical) of a dental filler were
obtained; the composition of this was in keeping with the
analyses values found as in the following formula:
n C3H7-SiO3/2 ~ 10 Sio2 ~ AlO3/2
Specific surface area: 78 m2/g
Example 4
17.83 g (0.1 mol) of H3C-Si(OC2Hs)3, 14.83 g (0.1 mol) of
(CH3)2Si(OC2Hs)2, and 14.62 g (0.1 mol) of HsC2Al(OC~Hs)2 were
combined. The mixture was stirred for 6 hours during
refluxing, then 416.7 g (2 mol) of Si(oC2Hs)4 was added to it
and it was then diluted within 10 minutes with 200 ml of
ethanol and subsequently 200 ml of a 5% aqueous Nh3 solution
-- 22 --

2~7~28
was added to it. This was stirred for a further period during
refluxing, until gelling began. After dilution with 500 ml of
H2O, stirring was continued for a further 2 hours during
refluxing, and the mixture was then processed as in Example 1.
140.2 g (99.1% of the theoretical) of a dental filler, the
composition of which was in keeping with the analyses values
found, were obtained, this being of the following formula:
H3C-SiO3/2 ~ (H3C)2siO2/2 20 SiO2 H5C2AlO3/2
Specific surface area: 46 m2/g
Example 5
375.0 g (1.8 mol) of Si(OC2Hs)4, 14.9 g (0.06 mol) of
methacryloyloxypropyltrimetho~ysilane, and 9.73 g (0.06 mol)
of Al(OC2H5)3 were combined in a 2-litre glass vessel with a
KPG stirrer, an internal thermometer, and a reflux cooler. The
mixture was mixed with 100 ml of 10% ethanolic NaOC2Hs
solution within 5 minutes. The clear solution was then
stirred for 2 hours during refluxing, and then 100 ml of 1%
aqueous NH3 solution were added to it within 10 minutes. The
gel that formed spontaneously was diluted with 400 ml of water
and stirred for a further 15 minutes during refluxing, then
cooled down and the solid filtered off from the liquid phase.
The moist solid was then divided into two equal parts.
a) 1 part was mixed with 150 ml of aqueous NaOH
solution at pH 11.7 and stirred for 24 hours at 150~C in an
autoclave at the pressure that was generated.
b) The second half of the moist product was mixed with
150 ml of 5% aqueous NH3 solution and stirred for 24 hours at
150~C in an autoclave at the pressure that was generated.
After treatment both products were washed with water until
neutral and dried for 24 hours in a nitrogen atmosphere at
- 23 -

2~7~ 2~
120~C. The total yield amounted to 119 g (97.6 % of the
theoretical).
The analyses data found were in keeping with the composition:
CH O
1 311
CH2=c-c-o-(cH2)3sio3/2 ~ 30 SiO2 Al~3/2
Specific surface area:
Product a) 152 m2/g
Product b) 136 m2/g
Example 6
Starting from 375.0 g (1.8 mol) of Si(OC2H5)4, 8.9 g ~0.06
mol) of (CH3)2Si(OC2Hs)2, and 14.8 g (0.06 mol) of Al(OC~Hg)3,
exactly the same procedure as in Example 5 was followed. What
was obtained was a product of the following composition:
(CH3)2SiO2/2 ~ 30 SiO2 ~ AlO3/2
at an almost quantitative yield.
Specific surface area:
: Product a) 137 m2/g
Product b) 90 m2/g
- 24 -

2~7~
II. Production of the dental materials according to the
present invention
The fillers from Examples 1, 2, 5, 6, with an average grain
size of 15 microns, were used to produce the dental substances
according to the present invention. The fillers were
silanized by the usual procedure with 3-methacryloyl-
oxypropyltrimethoxysilane. The fillers were incorporated in a
monomer matrix in quantities varying from 51 to 62% (m/m) as
they are usually used for dental plastics. Initiators were
added, and the substances were kneaded to form homogenous
pastes.
A number of physical properties of the hardened test bodies
that were produced from the various pastes were determined,
and these were then compared with the properties of
commercially available products and laboratory comparison
products (Table I).
Examples for the dental substances according to the present
invention:
1. Thermohardened dental substances according to the
present invention:
The production of test bodies from the thermohardening dental
substances according to the present invention was accomplished
such that the substances were pressed into the appropriate
molds for the test bodies and then hardened in a water bath
for 30 minutes at a pressure of 6 atmospheres at 90~C.
- 25 -

2~7~12g
Example No. 15 (quantities in parts by weight)
61.5 filler no. 1
14.3 bis-GMA
11.O UDMA
11.O TEDMA
2.2 dibenzoylperoxide
Example No. 16 (quantities in parts by weight)
53.0 filler no. 3
4.5 highly dispersed SiO2
22.2 UDMA
8.0 bis-GMA
10.O TEDMA
2.5 dibenzoylperoxide
Example No. 17 (quantities in parts by weight)
50.4 filler no. 5a
5.0 highly dispersed SiO2
22.6 UDMA
8.3 bis-GMA
10.4 TEDMA
3.3 dibenzoylperoxide
Example No. 18 (quantities in parts by weight)
58.3 filler no. 6a
: 15.9 bis-GMA
11.9 UDMA
11.9 TEDMA
2.0 dibenzoylperoxide
- 26 -

2~7~28
2. Photohardened dental substances according to the
present invention:
The photohardening dental substances ac~cording to the present
invention consist of transparent pastes that are hardened by
being irradiated with a medical halogen lamp (Degulux
Degussa). The irradiation time amounts to 100 sec.
Example No. 19 (quantities in parts by weight)
48.3 filler no. 1
6.0 highly dispersed SiO2
22.6 UDMA
8.2 bis-GMA
10.3 TEDMA
4.6 initiators
Example No. 20 (quantities in parts by weight)
47.9 filler no. 2
4.4 highly dispersed SiO2
23.6 UDMA
8.6 bis-GMA
10.8 TEDMA
4.7 initiators
Example No. 21 (quantit~es in parts by weight)
42.9 filler no. 5b
6.7 highly dispersed SiO2
25.0 UDMA
9.1 bis-GMA
11.3 TEDMA
5.0 initiators
Example No. 22 (quantities in parts by weight)
44.6 filler no. 6a

2 ~ 7 ~
6.5 highly dispersed SiO2
24.3 UDMA
8.8 bis-GMA
11.O TEDMA
4.8 initiators
~bbreviations:
Bis-GMA: 2,2-bis[p~ methacryloyloxy-beta-
hydroxypropoxy)-phenyl]-propane
UDMA: 7,7,9-trimethyl-4,13-dioxo-3,14-dioxa-
5,12-diazahexadecane-1,16-dioldimethacrylate
TEDMA: triethyleneglycoldimethacrylate
Commercial products:
Commercial products with which the dental substances set out
in Table I are compared:
Conventional composite (Estilux, Kulzer): a silanized lithium-
aluminum-glass with a mean grain size of approximately 4
microns serves as a filler. The filler'content is
approximately 75% ~m/m).
Hybrid composite (Degufill H, Degussa): a silanized barium-
aluminum-silicate-glass with a mean grain size of
approximately 2 microns, but of which up to 100% finer than 5
microns, and silanized highly dispersed SiO2 serve as filler.
The degree of filling wlth glass amounts to approximately 70%
(m/m) and the degree of filling with highly dispersed SiO2 is
approximately 11% (m/m). This results in a total content of
inorganic fillers of approximately 80% (m/m).
Microfiller composite (Durafill, Kulzer): a silanized highly
dispersed SiO2 with a mean grain size between 0.01 to 0.04
- 28 -

2 ~ 7 '~
microns serves as filler. The degree of filling amounts to
approximately 50% ~m/m).
All of these substances were hardened with the Degulux Degussa
lamp that was used for an irradiation time of 40 seconds.
Thermohardening laboratory test products = VP (details in
parts by weight):
VP1: 17 bis-GMA
7.7 TEDMA
barium-aluminum-silicate-glass,
silanized (mean grain size approximately 4 microns)
0.3 dibenzoylperoxide
VP2~ 35 bis-GMA
1~.7 TEDMA
highly dispersed SiO2, silanized
(mean grain size 0.01 to 0.04 microns)
0.3 dibenzoylperoxide
These pastes were hardened analogously to the hardening
carried out for the thermohardening substances according to
the present in~ention.
- 29 -

2~7~
Testing and assessment of polishability:
Test bodies, 15 mm diameter and 3 mm thick, were produced from
all the materials. The surfaces of all the test bodies were
first smoothed with a 600 grit abrasive paper. They were then
polished under water with the finest possible aluminumoxide
(mean particle size 0.04 microns) on a cotton cloth.
The polishability was assessed visually and noted on a poi.nt
scale between 1 and 5, with 1 being dull and 5 standing for a
high lustre.
- 30 -

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- 30a -