CA2015081A1 - Paste-like dental material - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE

The present invention relates to a paste-like dental material that can be hardened in the presence of an initiator to form a substance that can be polished to a high lustre, from a polymerisable binding agent and a fine-grain filler based on special organopolysiloxane compounds that are described in the claims and to the various uses of the material in the field of dentistry.

Description

20~8~

The present invention relates to a dental material that is in the form of a paste, that hardens in the presence of an initiator to a mass that can be polished to a high lustre, said dental material consisting of a polymerisable organic binding agent and a fine-grained filler. The material contains at least one polymerisable methacrylate and an optionally silanisable, new type, filler based on functional polysiloxanes as binding agent. In addition to this, initiators for starting polymerisation, additional fillers such as finely-ground glasses, highly dispersed silicic acid or preformed polymers, pigments and stabilisers can also be contained in it. Other additives such as softeners or additives to improve impact strength can also be used.

The term "dental material" includes, for example, filling materials for use in caries defects or other tooth defects within the mouth, inlays, crown and bridge materials, blends, substances for sealing and protective coatings, plastic strengthening materials for holding inlays or crowns and bridges, materials used to build up broken teeth, materials used for prostheses, and the materials used for the production of false teeth.

Conventional dental substances of the type described above 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, methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, n-hexyl methacrylate, and 2-hydroxyethyl methacrylate.

Recently, multifunctional esters of methacrylic acid with high molecular weights have also been used, these being ethyleneglycoldimethacrylate, butanediol-1,4-dimethacrylate, triethyleneglycoldimethacrylate, dodecandiol-1,12-dimethacrylate, decandiol-1,10-dimethacrylate, 2,2-bis-[p(gamma-methacryloxy-beta-hydroxypropoxy)-phenyl]-propane, ., , . , ~ . :

.

8 ~

the diaduct oE hydroxyethylmethacrylate and trimethylhexamethylenediisocyanate, the diaduct of hydroxyethylmethacrylate and isophorondiisocyanate, trimethylolpropanetrimethacrylate, pentaerythrittrimethacrylate, pentaerythrittetramethacrylate, and 2,2-bis[p(beta-hydroxy ethoxy)-phenyl]
propanedimethacrylate (bis-GMA).

The materials used for dental purposes can be hardened in various ways, depending on the purpose Eor which they are used. There are both photohardened as well as self-hardened (autopolymerising) substances used for tooth filling materials. The photohardened substances contain photoinitiators such as benzoinalkylether, benzilmonoketales, acylphosphinoxides, or aliphatic and aromatic 1,2-diketo compounds such as campherchinon and polymerisation accelerators such as aliphatic or aromatic tertiary amines (e.g., N,N-dimethyl-p-toluidin triethanolamine) or organic phosphites, and harden when irradiated with ultra-violet or visible light.

As a rule, the self-hardened materials consist of a catalyst paste and a base paste, of which each contains a component element of a redox system and which polymerise when the two components are mixed. The one component of the redox system is in most instances 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 used for dental prostheses or plastic substances used for the production of false teeth can be polymerised by the action of heat. ~ere, as a rule, peroxides such as dibenzoylperoxide, dilaurylperoxide or Bis(2,4-dichlor-benzoylperoxide) are used as initiators.

2~0~1 As a rule, den-t~1 materials also contain pigments which, added in the appropriate quantities, serve to match the colour of the dental masses to the various shadings of natural teeth. Suitable pigments used Eor this purpose 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.

In addition, dental materials contain mostly organic or inorganic fillers. This is done in order to prevent the plastic substance shrinking during polymerisation. Pure monomer methylmethacrylate shrinks by approximately 20%-volume on polymerisation, for example. This shrinkage can be reduced to approximately 5-7~ by the addition of approximately 60 parts-weight of solid pearl polymeride (DE-PS 24 03 211).

Other organic fillers are obtained in that one produces apolymerisate that essentially consists of esters of methacrylic acid and is either not cross-bonded or cross-bonded. Optionally, this polymeriside contains surface-treated fillers. It is produced as a polymerisate and can beadded to the dental material in this form; in contrast to this, it can be produced by substance polymerisation in compact form, so that prior to incorporation in the dental material it must first be ground to form a so-called splinter polymerisate.

In addition to the previously discussed pearl and splinter polymerisates, preformed polymerisates that are frequently used are homopolymerisates of th~ methacrylic acid methylesters or, preferably not cross-bonded, copolymerisates of the methacrylic acid methylester with a small fraction of esters of methacrylic acid or acrylic acid with 2 to 12 C
atoms in the alcohol component, more appropriately in the form of a pearl polymerisate. Other suitable polymerisates , ' , ' ' , . , .' :.

20~081 are uncross-bonded products based on polyurethanes, polycarbonates, polyesters and polyethers.

Inorganic fillers are, for example, ground glasses or quartz with mean particle sizes between approximately 1 and 10 ~m as well as highly dispersed SiO2 with a mean particle size between approximately lo and ~oO nm.

I'he glasses are preferably aluminum silicate glasses that can be doped with barium, strontium, or rare earths (DE-PS 24 58 380).

With regard to the finely ground quartz or the finely ground glasses, as well as with regard to the highly dispersed sio2, it should be noted that, as a rule, the inorganic filler is silanised prior to being mixed with the monomers so as to enhance the bond to the organic matrix. To this end, the inorganic fillers are coated with silane coupling agents that in most instances have a polymerisable double bond for reaction with the monomer esters of the methacrylic acid.

Suitable silane coupling agents are, for example, vinyltrichlorsilane, tris-(2-methoxyethoxy)-vinylsilane, tris-(acetoxy)-vinylsilane and 3-methacryloyloxy-propyltrimethoxysilane.

The newly used monomers, discussed above, which are of high molecular weight, also bring about a reduction of polymerisation shrinkage. Now, the above-described inert inorganic finely-ground glasses or organic fillers or mixtures of these are added to these monomers up to approximately 85%-wt, whereby a further reduction of the shrinkage to approximately 1%-vol can be achieved.

The inorganic fillers not only bring about a reduction of polymerisation shrinkage, but also effect a considerable strengthening of the organic polymer structure.

20150~1 This strengthening can be plainly seen in an improvement of the mechanical properties, as well as in an increase of the resistance to wear (R. Janda, Quintessenz ~Quintessence), 39, 1067, 1243, 1393 (1988). Good mechanical properties and a high level of resistance to wear are important requirements that must be possessed by a dental mass that is intended to provide a permanent replacement for the hard substance in a tooth.

In addition to satisfying the requirement for strengthening properties, the fillers must also be able to satisfy other material parameters. One important parameter in this connection is the degree to which it can be polished. The capability of being polished to a high lustre is of considerable importance for filling materials and crown and bridge materials for at least two reasons:

- For esthetic reasons, a highly lusterous and completely homogenous surface is demanded of filling material so that the filling can no longer be distinguished from the surrounding, absolutely smooth and natural tooth material.
In addition, this high-lustre filling surface must retain its character over the long term.

- An extremely smooth surface for the filling is also important in order that plaque or staining media can find no mechanical anchoring points.

Now, however, it has been shown that the above-described finely-ground quartz or glass fillers have good strengthening properties although they do not meet the requirements for polishability. For this reason, attempts have been made to grind these inorganic fillers more finely in order to obtain a more homogenous surface. However, limits are imposed on the physical grinding methods used, so that average grain sizes of smaller than 1 micrometre are extremely difficult to obtain.

20~08:~

When one used highly dispersed silicic acid (mean particle size 10-400 nm) as a filler in clental substances (DE-PS 2~ 03 211), it was shown, most surprisingly, that a considerable improvement in polishability could be achieved by using these fillers. A disadvantage of the highly dispersed silicic acid is its marked thickening effect, so that today, as a rule, it is not possible to achieve filling levels above 52%-wt, unless one is satisfied with inade~uate processing and machining characteristics.

Furthermore, materials filled with highly dispersed silicic acid exhibit greatly reduced strength and hardness compared to those Eilled with quartz or finely-ground glasses.

It is the task of the present invention to describe a new light, heat, or self-hardened dental materials produced from a polymerisable organic binding agent and a finely-divided filler that can, on the one hand, be polished to a high lustre and thereby satisfy the esthetic demands imposed on dental material, and on the other, which have improved physical properties compared to the polishable dental materials that represent the present state of the art.

Accordingly the invention provides a new paste-form, hardening dental material that hardens in the presence of an initiator and can be polished to a hiyh lustre and which is produced from a polymerisable organic binding agent and a finely-divided filler has been developed, this c`ontaining an organopolysiloxane as the filler, this being composed of units of the formula -0-Si-0 2 ~

and units of ~he formula I

-o-si-o-I (II) wherein R1 stands for a linear or branched alkyl group with 1-6 C atoms that is connected to an acrylate or methacrylate radical/ or for a simple olefin unsaturated, preferably end-position unsaturated linear, optionally branched, hydrocarbon radical with 2-8 C atoms, or for a cyclic, simply olefin unsaturated hydrocarbon radical with 5-8 C atoms, or for a linear, optionally branched alkyl group with 1-8 C atoms, a phenyl group, a cycloalkylene group with 5-8 C atoms, or an alkylaryl group, and/or units of the formula -0-l i-o- (III) .

in which R2 stands for a methyl, ethyl, or phenyl group, and the free valencies of the oxygen atoms bonded to the silicon atoms are saturated in the units (I), (II), and (III) as in the silicic acid structures by a silicon atom of an equal or different unit, the ratio of the silicon atoms from the units of formula ~I) to the sum of the silicon atoms of the units (II) and (III) amounting to.3:1 to 100:1.

The units of formula (I) to (III) can naturally exist in various forms that differ from each other, i.e., they can be 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. According to the present invention, ., ,, .:
' 201~081 relative to the units of formula (I) to (III), the fillers of the new dental material can be present in each of the above forms and in mixtures thereof.

This means, that in the case of a purely statistical copolycondensate, that contains units of formula (I), (II), and/or (III), a purely statistical distribution of the components corresponding to the moLecular ratio of the starting products is formed.

In the case of a so-called block-copolycondensate, there is a formation of blocks of equal units of formula (I) and (II) and/or (III). Finally, a so-called mixed copolycond~nsate has both the structure of a statistical copolycondensate and of a block-copolycondensate as well.

The fillers according to the present invention are used in dental substances in a quantity of 20 to 90%-wt, and preferably 50 to 85%-wt. The unsaturated organic radical that may exist on the units of formula (II) can serve primarily to provide for a more solid bonding of the polysiloxane filler to the polymer matrix that is subsequently produced from the polymerisable organic binding agent.

For this reason, organic radicals Rl, in which a double bond is easily accessible sterically, are particularly suitable.
This applies in particular for the group Il I
- 1 CH2 ) 3-o-C-C=CH2 because its particularly easily obtained polymerisa~ility is known and, in addition, in the polymer matrix in which the 2Dl~

filler is to be incorporated this i5, as a rule, a methacrylate system, both for linear hydrocarbon radicals with an end position double bond, such as, for example, the vinyl-butenyl- or octenyl radical. But cyclic hydrocarbon radicals with polymerisable double bonds are also suitable.
In many cases, Rl can be one of the double-bond free organic radicals that are also cited under formula (II).

A particularly advantageous composition of the filler, which is distinguished by simple realization and primarily by the technical availability of the starting materials, makes provision for the fact that an organopolysiloxane is used as a ~iller, this consisting only of the units of formula (I) and the special units of formula (II), o O CH3 O-Si- ~ CH2 ) 3-o-C-C=CH2 the molecular ratio of the units of formula (I) to the units of (II) amounting to 3:1 to 100:1. A filler of this type is distinguished by the fact that in order to be introduced into the methacrylate matrix, it is in principle no longer silanized, i.e., it has to be treated with a methacrylsilane, after which these methacryl groups are already present in the filler in a homogenously distributed state.

25 However, this does not preclude the fact that in an individual case, with regard to further hydrophobising with additional strengthening of the bonding between the organopolysiloxane filler and the organic polymsr matrix, additional silanisation of the filler will be undertaken.

2 ~ 8 ~

Most surprisingly, when the invention was being prepared, it was found that very good mechanical properties and polishability of the dental material can also be achieved if the organosiloxane filler that is used containes no unsaturated, but only saturated ~1 radicals.

This applies both to the filler, the units of formula (I), (II) and (III), and for such fillers that contain only units of formula (I) and (II). Such organopolysiloxane fillers that are not double-bond functional should be treated with a suitable organosilane compound, preferably 3-methacryloyloxy-propyltrimethoxy- or 3-methacryloyloxypropyltriethoxysilane, before being introduced into the organic polymer matrix.

The same thing applies to a filler composition that is advantageous because of the particularly easy availability of the starting materials, this composition forseeing building up the polysiloxane from units of formula (I) and the special units of formula (III), -o-si-o . I
,, CH3 the molecular ratio of the units according to formula (I) to the units of formula (III) amounting to 3:1 to 100:1.

The monomer building blocks of the fillers according to the present invention are compounds that are known in principle, for example Si(OC2Hs)4 as a monomer component for one unit of formula (II) and a compound (H3C0)3Si-tCH2~3-O-C-C=CH2 (H3Co)3Si-CH2CH2CH3 -- 10 ~

20150~1 as a monomer building block for units of formula (II) and a compound (H3C)2Si(oC2H5)2 as a monomer building block for units of formula (III).

The composition of the dental substances according to the present invention that can be built up therefrom can be described, for example, by formulas for a particular polymer unit such as 2 H2 C 1~ 0-(CH2)35io3l2- ~CH3)2sio2/
o 23 7 3 / 2 I H5 C2 ~ 2 Si2 t 2 50 SiO2~H ~C)zSiO2/2 l H3 30 SiO2 CH2:C-C-o-(CH2)3Sio3~2 o A typical acid catalyst is, for example, hydrochloric acid or acetic acid, whereas, for example, in addition to ammonia, amines represent a typical base catalyst.

With regard to physical properties, fillers of a composition according to the present invention are particularly well suited for use in the dental materials according`to the present invention if they have a specific weight per unit area of approximately 0 to 200 m2/g, preferably approximately 0 to 100 m2/g, and a particle size of 0.01 ~m, preferably 0.1 ~m to 30 ~m.

The fiilers contained in the dental material according to the present invention can be obtained by various methods. One of these foresees that an alkoxysilane of the general formula . . .

.. . ..

~5~

si(~R3~ (IV) wherein R3 stands for a linear or branched alkyl group with 1 to 5 C atoms, and an alkoxysilane of tha general formula R1 - Si(oR3)3 (V) in which R1 is of the same value as in formula (II) and/or an alkoxysilane of the general formula ~R2)2Si~oR3)2 (VI) in which R2 is the same value as in formula (III~, is dissolved in a largely water miscible solvent which, however, dissolves the sil.anes of formula (IV), (V) and (VI); then a quantity of water that is at least sufficient for complete hydrolysis and condensation is added during stirring; the reaction mixture is then precondensed during continued stirring at a specific temperature in the range from room temperature to 200C, the solids that are forming are stirred, optionally with the addition of further solvent or water for a further 1 hour to 6 hours at 60C to 200C, at normal pressure or at a pressure that corresponds to the sum of the partial pressures at the particular temperature, and then the polysiloxane that has been formad if processed, optionally after changing the medium and/or pH value for 4 hours to 5 days at 100C to ~50C in the liquid phase; then, using the customary techniques, it is separated off from the liquid phase, and the polysiloxane is optionally washed, dried at room temperature to 200C, optionally in an atmosphere of protective gas or in a vacuum, and then, optionally, this is tempered for 1 to 100 hours at temperatures from 150C to 250C in an atmosphere of protective gas or in a vacuum; one then optionally grinds and/or grades this; when this is done one processes the organopolysiloxane that has been separated off from the liquid phase and optionally washed prior to or after one of 2~1~081 the stages of drying, tempering, grinding, grading, in water, a water/alcohol mixture or in pure alcohol, in the presence of an acid or base catalyst, preferably in the presence of ammonia, for a period varying from 1 hour to 5 days at temperatures from 60C to 250C at a pressure that corresponds to the sum of the partial pressures at the particular temperature.

The advantageous application characteristics of the new fillers are attributable to the acid or alkyline temperature treatment prior to or after drying or in a processing stage that is optionally still applied, since above all else a consolidation of the polymer structure is achieved by this.

In principle, in place of the alkoxy compounds, the corresponding halogenide or phenoxy compounds can be used as starting materials for the process, although their use offers no advantages but can cause difficulties, for example in the case of the chlorides, because of the hydrochloric acid that is liberated during hydrolysis.

Hydrolysis of the monomers must be carried out in a largely water miscible solvent that, however, dissolves the starting materials. It is preferred that alcohols are used that corresponds to the alkoxy groupings on the monomer starting substances.

Especially suitable are methanol, ethanol, n- ana i-propanol, n- and i-butanol and n-pentanol. Mixtures of such alcohols can be used as solvents during the hydrolysis.

of course, in place of alcohols, one can also use other polar solvents that are largely water miscible, although this is not as useful for reasons of process technology because of the solvent mixture that is formed with the hydrolytically separated alcohol.

2~50~1 It is preferred that one carries out the hydrolysis with an excess of water beyond the stoichiometric required quantity.
The quantity of water that is required for hydrolysis depends on the speed of hydrolysis of the monomers used in each case, such that more rapid hydrolysis takes place as the quantity of water increases, although an upper limit can be set by separation and formation of a two-phase system that occurs.
As a matter of principle, hydrolysis in a homogenous solution is to be preferred.

Because of the above aspects, in practice, the maximum quantity of water by weight is used as is used in total with regard to the silane monomers. (redo) The polycondensation can be carried out at di~ferent temperatures. Because of the fact that polycondensation takes place quickest at higher temperatures, it is preferred that this be done at reflux temperature or just below this.
In principle, hydrolysis and polycondensation can be carried out at still higher temperatures than reflux temperature, i.e., under pressure.

The reaction mixture can solidify to a solid mass during polycondensation. For this reason, it is appropriate to add a suitable quantity of solvent or water in order to thin it.

When this is done, the solvent will, as a rule, be the same as was used during the hydrolysis of the silanes; i.e., a low alcohol with 1 to 5 C atoms is preferred.

Of course, water can be used for the thinning as an alternative to thinning with a solvent. Whichever is used in an individual case will depend on which physical properties the copolycondensate that is produced is to have. Depending on circumstances, one of the processing stages such as washing, drying, tempering, grinding and grading can be 2~ns~

omitted or else the sequence can be carried out in a different order.

Separation of the solid that is formed can be effected by available techniques such as filtering, decanting, centrifuging, or by distilling off the liquid phase. Washing of the solid that is formed using the solvent used during precipitation or with water is preferred.

The dried or tempered product can be ground in various apparatuses and graded into various grain sizes. Depending on circumstances, one or the other of the stages such as washing, drying, tempering, grinding and yrading can be eliminated, or they can be carried out in a different sequence.

Grading can, for example, be carried out on a product that i5 moist or, optionally, previously dried or tempered.

The duration of the hydrolysis will depend on the amenability of the starting material to hydrolysis and on the temperature. The rate of hydrolysis depends, in particular, on the siiicon-bonded alkoxy groups, the methoxy group hydrolysing the most rapidly, with the process slowing down as the chain length increases or with increasing branching.
Hydrolysis and polycondensation can be accelerated by the addition of organic or inorganic bases such as, for example, ammonia or amines, or organic or inorganic acids, such as, for example, hydrochloric acid, or of conventional condensation catal~sts such as, for example, dibutylstannousdiacetate.

In order to compensate for the varied hydrolysis and polycondensation behaviour of the monomer components of a statistical copolycondensate, according to one production variant, the monomer components of formula (IV), (V) and/or (VI) can be precondensed. To this end, these monomer 2~0~

components are precondensed wi-thout or with the use of a solvent that dissolves the starting substances, linear or branched alcohols with 1 to 5 C atoms that correspond to the alkoxy groups being preferred, in the presence of a quantity of water that is not sufficient for complete hydrolysis, preferably 1 to loo mol-~ of the quantity required, for a period of 5 minutes to up to 5 days at room temperature to 200C.

In order to enhance this precondensation effect, an acid or lo base condensation catalyst can be added. Examples of preferred catalysts are hydrochloric acid, acetic acid, ammonia, caustic soda, or caustic potash, that are used in gas form or dissolved in water or in an organic solvent.

After successful precondensation, complete hydrolysis and polycondensation, optionally after the addition of extra water and optionally after the addition of additional solvent, is carried out as described.

According to one other method, so-called block copolycondensates are obtained, in which a formation of blocks of equal units of formula (I) and ~ and/or (III) are present. This process provides for the fact that one precondenses the monomer components according to formula (IV), (V) and/or (VI) independently of each other, without or with the use of a solvent that dissolves the starting substances, the linear or branched alcohols with`l to 5 C
atoms that correspond to the alkoxy groups being preferred, in the presence of a quantity of water that is insufficient for complete hydrolysis, preferably of 1 to 100 mol-~ of the quantity required for this purpose, for a period of time that varies from 5 minutes to 5 days at room temperature to 200C, next combines the condensates so obtained, and then optionally carries out the hydrolysis and polycondensation as described, optionally after the addition of extra solvent.

2 1~ 8 3L

Of course, one of the above-described condensation catalysts can be used in this production variant according to the present invention.

According to another method, so-called mixed copolycondensates are obtained in which in part there is formation of blocks of the same units as in formula ~I) and (II) and/or (III) in which, however, always at least one monomer component is not precondensed and at least one monomer component is precondensed.

This process provides for the fact that of the monomer components of formula (IV), (V), and/or (VI) one precondenses at least one monomer but at most two monomers independently of each other, without or with the use of a solvent that dissolves the starting substances, linear or branched alcohols with 1 to 5 C atoms, preferably corresponding to the alkoxy groups being preferred, in the presence of a quantity of water that is insufficient for complete hydrolysis, prefarably from l to 100 mol-% of the quantity required for this purpose, over a period of 5 minutes to up to 5 days at room temperature to 200C, and then combines the precondensates so obtained and at least one not precondensed component with each other and then, optionally after the addition of extra water and optionally after the addition of extra solvent, carries out complete hydrolysis and polycondensation as described heretofore.

The use of an acid or base condensation catalyst and/or one that contains metal for precondensation is also possible in this production variant and the further processing of the polycondensate so formed is set up in the same way as in the other production method described above.

The quantity of water that is used during precondensation will depend on which degree of oligomerisation, i.e., which block size, is to be achieved. When more water is used for ~0~081 precondensation and/or longer precondensation times are used, nat~lrally, fundamentally greater units will result than when less water and/or shorter reaction times are used. As has already been described the duration of the precondensation depends generally on the amenability of the monomer components to hydrolysis, and the temperature.

The filler materials for the new dental materials are distinguished in particular on the basis of the quantitative hydrolysis and condensation yield and element analysis. From the purely visual point of view there is no difference between the copolycondensates obtained by means of the various production processes. Depending on treatment, the fillers according to the present invention have surfaces of approximately 0 to 200 m2/g~ The desired particle size diameter of 0.01 ~m to 100 ~m can be adjusted without any problem by the use of existing grinding techniques.

A further object of the present invention is the use of the dental material according to the preceding demands for the production of tooth fillings, inlays, tooth sealing, overlays to protect the surface of the teeth, crowns, blends, bridges, dental prostheses, artificial teeth, and adhesives for securing in-lays, crowns and bridges as well as for building up broken teeth.

The present invention is explained in greater detail below on the basis of embodiments.

I. Production of the fillers to be used according to the present invention:

~L

1,465.2 g (7.03 Mol) Si(OC2Hs)4 and 34.8 g (0.234 Mol) (CH3)2Si(oC2H5)2 were dissolved in 750 ml ethanol. The solution was heated to refluxing temperature when 525 ml of 2 ~

10% aqueous ammonia solution were added. Stirring was first carried out for one-half hour during refluxing and then the - solid that was formed was thinned with 750 ml water. After a further 2 hours of stirring during refluxing the suspension was cooled to room temperature and the white solid that had been formed was filtered off from the liquid phase and washed with a total o~ 500 ml of water. 700 ml of 2% NH3 solution ' was added to the solid and it was then moved into an autoclave. After 24 hours of temperature processing of the autoclave contents at 150C, the solid was dried for 24 hours at 120C in a drying cabinet in an atmosphere of nitrogen and then ground for 24 hours in a ball mill.

437.2 g (99.4% of the theoretical yield) of a dental filler, consisting of polymer units of the formula (CH3)2siO2/2~3osio2 was obtained.

Specific wei~ht per surface unit: 22 m2/g Analysis: % C % H % ~i Theoretical 1.28 0.32 46.4 Found 1.12 0.40 45.6 Example 2 1,456.5 g (6.99 Mol) Si(oC2H5)4 and 43.5 (0.175 Mol) methacryloyloxypropyltrimethoxysilane were combined in 750 ml of ethanol. The solution was heated in a 6-l triple neck flask with KPG stirrer and reflux cooler during stirring at reflux temperature. 500 ml 5% NH3 solution was mixed in at boiling temperature. After approximately one-half hour of stirring during refluxing the white solid that formed was thinned with 750 ml of water. Stirring was continued for a further 5 hours during refluxing and then the suspension was cooled to room temperature and the solid filtered off from 2 0 ~

the liquid phase. 500 ml of 5~ ammonia solution was mixed with the solid and this was then moved into an autoclave.

After 48 hours of stirring of the autoclave contents at 130DC
the solid was washed until it was free of ammonia and then dried for 24 hours at 100C in an atmosphere of nitrogen and finally ground for 12 hours in a ball mill. 450 g (99.6% of the theoretical yield) of a dental filler consisting of units of formula Cll 2 11 2)3 SiO3~2 40SiO2 o were obtained.

Specific wei~ht per surface unit: 23 m2/g Analysis: % C % H % Si Theoretical 3.26 0.43 44.6 Found 3.12 0.34 44.0 15 Example 3 1,431-8 g (6-87 Mol) Si(oc2Hs)4~ 42.7 g (0.172 Mol) methacryloyloxypropyltrimethoxysilane and 25.5 g (CH3)2Si(oC2H5)2 were combined in 750 ml of methanol. The solution was heated to reflux temperature when 450 ml of 5%
ammonia solution were added to it. After a further processing as in Example 2, 450 g (98.6% of the theoretical yield) of a dental filler, consisting of units of the formula CH2-C_c-o-~cH2~3-sio3l2- ~C~3125iO2/2 ~SiQ2 were obtained. 0 Specific weight per surface unit: 32 m2/g - .

2~1~081 Analysis: % C % H % Si Theoretical 4.07 0.64 44.4 Found 3.82 0.59 43.4 Example 4 722.9 g (3.47 Mol) Si(oC2~5)4, 14.3 g (0.0867 Mol) n-C3H7-Si(OCH3)3 and 12.9 g (0.0867 Mol) (CH3)2si(OC2H5)2 were dissolved in 375 ml of ethanol. The solution was heated to reflux temperature and 200 ml ln-HCl solution were added to it. The solid, which formed after 1 hour, was diluted with 400 ml of methanol and then stirred for an additional half hour during refluxing. The solid that was next filtered off had 500 ml of 10% ammonia solution added to it and was stirred for 15 hours in an autoclave at 150C. After additional processing as in Example 2, 220.0 g (98.6% of the theoretical yield) of a dental filler, consisting of units of the formula 3H7Sio3/2 ~cH3)2sio2/2 . ~0 Si02 were obtained.

Specific weiqht per surface unit: 56 m2/g Analysis: % C % H~ % Si Theoretical 2.3 0.51 45O9 Found 2.1 0.40 44.8 Example 5 727.8 g (3.49 Mol) Si(oC2~5)4 and 22.2 g (0.1165 Mol) CH2=CH
Si(oC2H5)3 were combined with each other. The mixture was . . . : ......... : . , .
~ ..... ' " ' ' , 2 ~

stirred with 300 ml Oe o. 1 n acetic acid solution for 3 hours at 80C.

After this precondensation, ~00 ml of ethanol and 200 ml of water were added to the mixture and it was then stirred agai during refluxing. The solid that was formed after 2 hours of refluxing was filtered off and aEter being washed with a total of 1-1 of water was subjected to further processing as in Example 4. 216.0 g (98.5% of the theoretical yield) of a dental filler, consisting of units of the formula CH2=CH-sio3l2 30Sio were obtained.

S~ecific weiqht per surface unit: 22 m2/g Analysis: % C % H % Si Theoretical 1.28 0.16 46.3 Found 1.17 0.20 45.8 Example 6 727.8 g (3.49 Mol) Si(oC2H5)4 were added to 200 ml of 1%
aqueous ammonia solution and stirred for 2 hours at 100C.
Simultaneously, 19.0 g (0.07 Mol) (C6H6)2si(0C2H6)2 were added to 5 ml of ethanol and 0.5 ml of 2% aqueous ammonia solution and stirred for 10 hours at 100C. Next, the precondensates were combined and 500 ml of ethanol and 150 ml of 2% aqueous NH3 solution were added to it and it was then stirred for a further 3 hours during refluxing. The solid that formed was filtered off and after being washed with 500 ml of ethanol was subjected to further processing as in Example 4.

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After a subsequent 24 hour tempering at 150C in a nitrogen atmosphere, 220.0 g (98.1% of the theoretical yield) of a dental filler consisting of units of the formula ( C6~15) 2Si2/2 50sio2 were obtained.

Specific weiqht per surface unit: 31 m2/g Analysis: % C % H % Si Theoretical 4.50 0.31 44.7 Found 4.40 0.26 43.9 Example 7 17.3 g (0.087 Mol) (C6H5)Si(oCH3)3 had 0.2 ml of 2% methanol NH3 solution added to it and initially stirred for 5 hours at 60C. Then the precondensate was combined with 727.8 g (3.49 Mol) Si(oC2H5)4. After further processing as in Example 7, 216.3 g (98.2% of the theoretical yield) of a dental filler, consisting of units of the formula ~ 5 3~2 /OSiOz were obtained.

Specific weiqht per surface unit: 48 m2/g Analysis: % C % H % Si : Theoretical 2.85 0.20 45.5 Found 2.95 0.31 45.8 .
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~0~ 81 II. Production of the dental substance according ~o the present invention After production of the dental substances according to the present invention, the fillers from Examples no. 1 to no. 5 were ground down to a mean grain size o~ approximately 3 to 7 ~m in a ball mill. The fillers were then silanised with 3-methacryloyloxypropyltrimethoxysilane, using the usual process.

The fillers were introduced in quantities from approximately 70 to 73% (m/m) into a monomer matrix as is customarily used for dental plastics. Initiators were added and the mass was kneaded to form a homogenous paste.

A number of physical characteristics were determined on hardened test bodies produced from the various pastes and compared with commercially available products and laboratory comparison samples (Table I).

Checking and assessing polishability Test bodiés, 15 mm diameter and 3 mm thick, were produced from all the materials. The surfaces of all the test bodies were first abraded evenly with fine abrasive paper (600 grit). Then they were polished with the finest possible grade of aluminum oxide (mean grain size 0.0~ ~m) on à cotton cloth.

The polishability was assessed visually and noted by means of a point scale ranging from 1 to 5, where l = matt and 5 = a high lustre.

Examples for the dental ~ubstances according to the pres~nt invention . ~ :
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1. Heat hardened dental substances according to the present invention Production of the test bodies from the heat hardened dental substances according to the present invention was effected such that the masses were pressed into appropriate test-body moulds and then hardened in a water bath at a pressure of 6 atmospheres at 90~C for 30 minutes.

The following abbreviations are used in the examples which follow:

Bis-GMA: 2,2-Bis-[p-(~-methacryloyloxy-~-hydroxypropoxy)-phenyl]-propane TEDMA: Triethylenglykoldimethacrylate Example 9 (data in parts by weight):

73.0 filler as in Example 1 18.2 Bis-GMA

8.5 TEDMA

0.3 dibenzoylperoxide Example 10 (data in parts by weight):

70.0 filler as in Example 2 20.3 Bis-GMA

9.4 TEDMA

0.3 dibenzoylperoxide 201~i0~

Example ll tdata in parts by weight):

70.0 filler as in Example 3 20.3 Bis-GMA

9.4 TEDMA

5 0.3 dibenzoylperoxide Example 12 (data in parts by weight):

71.0 filler as in Example 4 19.6 BiS-GMA

9.1 TEDMA

0.3 dibenzoylpereoxide Example 13 (data in parts by`weight~:

73.0 filler as in Example 5 18.2 Bis-GMA

8.5 TEDMA

0.3 dibenzoylperoxide 2. Photohardened dental substances according to the present invention The photohardened dental masses according to the present invention consists of a white paste that is hardened by exposure to a dental halogen lamp (Translux, Kulzer). The radiation time amounts to 100 seconds.

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Example 14 (data in parts by weight):

70.0 filler as in Example 2 19.0 Bis-GMA

8.7 TEDMA

0.2 Campherchinon 0.1 N,N-Dimethyl-p-toluidine Commercial products, with which the dental substance according to the present invention as set out in Table I are compared:

Conventional composite (Estilux, Kulzer):

A silanised lithium-aluminum glass of an average grain size of approximately 4 ~m serves as a filler. The filler content is approximately 75% (m/m).

Hybrid composite (Degufill H, Degussa):

Silanised barium-aluminum-silicate glass with an average grain size of approximately 2 ~m but which is up to 100%
finer than 5 ~m serves as a filler as does as a silanised highly dispersed SiO2. The degree of filler in the glass amounts to approximately 70% (m/m) and that of the highly dispersed sio2 is approximately 11% (m/m). This results in a total content of inorganic fillers of approximat~ly 8% (mjm).

; Microfiller composite (Durafill, Kulzer & Co. GmbH):
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A silanised highly dispersed SiO2 with a mean grain size between 0.01 and 0.04 ~m serves as a filler. The degree of filling amounts to approximately 50% (m/m).

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Thermo-hardened laboratory test product = VP (data in parts by weight):

VP1:17 Bis-GMA

7.7 TEDMA

Barium-aluminum-silicate glass, silanised (average grain size approximately 4 mlcro-metres) 0.3 Dibenzoylperoxide VP2:35 Bis-GMA

14.7 TEDMA

highly dispersed sio2 silanized (average grain size 0.1 - 0.04 ~m) 0.3 Dibenzoylperoxide These pastes were hardened as were the heat hardened substances according to the present invention.

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Claims (13)

1. A paste-form, hardening dental material that hardens in the presence of an initiator and can be polished to a high lustre and which is produced from a polymerisable organic binding agent and a finely-divided filler has been developed, this containing an organopolysiloxane as the filler, this being composed of units of the formula (I) and units of the formula (II) wherein R1 stands for a linear or branched alkyl group with 1-6 C atoms that is connected to an acrylate or methacrylate radical, or for a simple olefin unsaturated, preferably end-position unsaturated linear, optionally branched, hydrocarbon radical with 2-8 C atoms, or for a cyclic, simply olefin unsaturated hydrocarbon radical with 5-8 C atoms, or for a linear, optionally branched alkyl group with 1-8 C atoms, a phenyl group, a cycloalkylene group with 5-8 C atoms, or an alkylaryl group, and/or units of the formula (III) in which R2 stands for a methyl, ethyl, or phenyl group, and the free valencies of the oxygen atoms bonded to the silicon atoms are saturated in the units (I), (II), and (III) as in the silicic acid structures by a silicon atom of an equal or different unit, the ratio of the silicon atoms from the units of formula (I) to the sum of the silicon atoms of the units (II) and (III) amounting to 3:1 to 100:1.

2. Dental material as claimed in claim 1, wherein the filler is present as a statistical copolycondensate, block polycondensate or as a mixture of these forms.

3. Dental material as claimed in claim 1, wherein R1 in the formula (II) stands for the group

4. Dental material as claimed in claim 1, wherein an organopolysiloxane is used as a filler, this consisting of units of formula (I) and units of formula (II) with the composition wherein the molecular ratio of the units of formula (I) to the units of (II) amounts to 3:1 to 100:1.

5. Dental material as claimed in claim 1, wherein an organopolysiloxane is used as a filler, this consisting of units of formula (I) and units of the formula (III) of composition the molecular ratio of the units of formula (I) to the units of (III) amounts to 3:1 to 100:1.

6. Dental material as claimed in any one of claims 1 to 5, wherein the filler has a specific weight per surface area of 0 to 200 m2/g, preferably 0 to 100 m2/g, and a particle size of 0.01 µm to 100 µm, preferably 0.1 µm to 30 µm.

7. Dental material as claimed in claim 1, wherein the filler contained therein is obtainable in the form of a statistical copolycondensate in that an alkoxysilane of the general formula Si(OR3)4 (IV) wherein R3 stands for a linear or branched alkyl group with 1 to 5 C atoms, and an alkoxysilane of the general formula R1 - Si(OR3)3 (V) in which R1 is of the same value as in formula (II) and/or an alkoxysilane of the general formula (R2)2Si(OR3)2 (VI) is dissolved in a largely water miscible solvent which, however, dissolves the silanes of formula (IV), (V) and (VI);
then a quantity of water that is at least sufficient for complete hydrolysis and condensation is added during stirring; the reaction mixture is then precondensed during continued stirring at a specific temperature in the range from room temperature to 200°C, the solids that are forming are stirred, optionally with the addition of further solvent or water for a further 1 hour to 6 hours at 60°C to 200°C, at normal pressure or at a pressure that corresponds to the sum of the partial pressures at the particular temperature, and then the polysiloxane that has been formed is processed, optionally after changing the medium and/or pH value for 1 hour to 5 days at 100°C to 250°C in the liquid phase; then, using the customary techniques, it is separated off from the liquid phase, and the polysiloxane is optionally washed, dried at room temperature to 200°C, optionally in an atmosphere of protective gas or in a vacuum, and then, optionally, this is tempered for 1 to 100 hours at temperatures from 150°C to 250°C in an atmosphere of protective gas or in a vacuum; one then optionally grinds and/or grades this; when this is done one processes the organopolysiloxane that has been separated off from the liquid phase and optionally washed prior to or after one of the stages of drying, tempering, grinding, grading, in water, a water/alcohol mixture or in pure alcohol, in the presence of an acid or base catalyst, preferably in the presence of ammonia, for a period varying from 1 hour to 5 days at temperatures from 60°C to 250°C at a pressure that corresponds to the sum of the partial pressures at the particular temperature.

8. Dental material as claimed in claim 7, wherein its filler is obtained in that hydrolysis and condensation are effected in methanol, ethanol, n- and i-propanol, n- and i-butanol and/or n-pentanol.

9. Dental material as claimed in claim 7, wherein its filler is obtainable in that one precondenses the monomer components of formula (IV), (V) and/or (VI) without or with the use of a solvent that dissolves the starting substances, preferred being a linear or branched alcohol with 1 to 5 C atoms that corresponds to the alkoxy groups, in the presence of a quantity of water that is insufficient for complete hydrolysis, preferably 1 to 100 Mol-% of the quantity required for this, for a period of 5 minutes to up to 5 days at room temperature to 200°C.

10. Dental material as claimed in any one of claims 1 to 5, wherein in that its filler is obtainable in the form of a block copolycondensate, in that one precondenses the monomer components according to formulas (IV), (V), and/or (VI) independently of each other, without or with the use of a solvent that dissolves the starting substances, linear or branched alcohols with 1 to 5 C atoms that correspond to the alkoxy groups being preferred, in the presence of a quantity of water that is not sufficient for complete hydrolysis, preferably 1 to 100 mol-% of the quantity required, for a period of 5 minutes to up to 5 days at room temperature to 200°C, combines the precondensates so obtained and then, optionally after the addition of extra water and/or additional solvent, carries out complete hydrolysis and polycondensation as in claim 7.

11. Dental material as claimed in any one of claims 1 to 5, wherein it filler is obtainable in the form of a mixed copolycondensate, in that one precondenses one monomer but at most two monomers of the monomer components according to formula (IV), (V), and/or (VI), independently of each other, without or with the use of a solvent that dissolves the starting substances, linear or branched alcohols with 1 to 5 C atoms that correspond to the alkoxy groups being preferred, in the presence of a quantity of water that is not sufficient for complete hydrolysis, preferably 1 to 100 mol-% of the quantity required, for a period of 5 minutes to up to 5 days at room temperature to 200°C, combines the precondensate or precondensates so obtained with at least one component that has not been precondensed and then, optionally after the addition of extra water and/or additional solvent, carries out complete hydrolysis and polycondensation as in claim 7.

12. Dental material as claimed in claim 9, wherein its filler is obtainable in that one uses an acid, base and/or metal-content condensation catalyst for precondensation.

13. The use of a dental material as claimed in any one of claims 1 to 5 for the production of tooth fillings, in-lays, blends, tooth seals, coatings to protect the surface of the tooth, crowns, bridges, teeth protheses, false teeth and adhesives for securing in-lays, crowns and bridges, and for building up broken teeth.