CA2074128C - Dental material with alumoorganopolysiloxane filler - Google Patents
Dental material with alumoorganopolysiloxane fillerInfo
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- CA2074128C CA2074128C CA002074128A CA2074128A CA2074128C CA 2074128 C CA2074128 C CA 2074128C CA 002074128 A CA002074128 A CA 002074128A CA 2074128 A CA2074128 A CA 2074128A CA 2074128 C CA2074128 C CA 2074128C
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
- A61K6/00—Preparations for dentistry
- A61K6/70—Preparations for dentistry comprising inorganic additives
- A61K6/71—Fillers
- A61K6/76—Fillers comprising silicon-containing compounds
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
- A61K6/00—Preparations for dentistry
- A61K6/20—Protective coatings for natural or artificial teeth, e.g. sealings, dye coatings or varnish
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
- A61K6/00—Preparations for dentistry
- A61K6/30—Compositions for temporarily or permanently fixing teeth or palates, e.g. primers for dental adhesives
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
- A61K6/00—Preparations for dentistry
- A61K6/80—Preparations for artificial teeth, for filling teeth or for capping teeth
- A61K6/884—Preparations for artificial teeth, for filling teeth or for capping teeth comprising natural or synthetic resins
- A61K6/887—Compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
- A61K6/00—Preparations for dentistry
- A61K6/80—Preparations for artificial teeth, for filling teeth or for capping teeth
- A61K6/884—Preparations for artificial teeth, for filling teeth or for capping teeth comprising natural or synthetic resins
- A61K6/891—Compounds obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds
- A61K6/896—Polyorganosilicon compounds
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- Health & Medical Sciences (AREA)
- Oral & Maxillofacial Surgery (AREA)
- General Health & Medical Sciences (AREA)
- Epidemiology (AREA)
- Life Sciences & Earth Sciences (AREA)
- Animal Behavior & Ethology (AREA)
- Public Health (AREA)
- Veterinary Medicine (AREA)
- Plastic & Reconstructive Surgery (AREA)
- Chemical & Material Sciences (AREA)
- Inorganic Chemistry (AREA)
- Dental Preparations (AREA)
- Compositions Of Macromolecular Compounds (AREA)
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.
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 --O-Si-O - (III) wherein R2 stands for a methyl, ethyl, propyl, or phenyl group and--in each of the compositions--has units of the formula - 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-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) 2~7~
--o-si -o 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~
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 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) 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 ~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 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.
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 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 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 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 ~-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 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 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
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 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.
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
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 --O-Si-O - (III) wherein R2 stands for a methyl, ethyl, propyl, or phenyl group and--in each of the compositions--has units of the formula - 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-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) 2~7~
--o-si -o 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~
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 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) 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 ~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 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.
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 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 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 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 ~-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 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 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
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 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.
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 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
11.9 UDMA
11.9 TEDMA
2.0 dibenzoylperoxide 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
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 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
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 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.
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.
2 ~ 2 ~
X ~ I ra ~ C ~ ~ ~ 1 Z
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T~ ~ ~3 oP H H _ H
_ ' ~ . ,~.
n -o ~ O ~ ~ O o _~
w ro ~ ~D ;
~ 1~ n r~ o o o o ~n ~ r~
~A) ~ (Jl o m O
i~D ~11 D
J' r~
~n ~ ~n ~I ~ ~n ~ o ~n _1 0 o ~ rr O 0 0~ ~ O 1--~ ~ o o o ~n --N ~ (n ~n O O ~n O O O o r-O ~n ~n ~n r ~n O O O O
y ~n W ~ O 1~
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X O
u~ ~n o o X X ~ o o o o ~ ~ o ~ ~ W o o o ~ ~
o ~n _ ~, r~ ~ o ~
o o o o o ~ .
~D
o o o r,~ r~
~n O
- 30a -
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.
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.
2 ~ 2 ~
X ~ I ra ~ C ~ ~ ~ 1 Z
-. à ~
~) t r~ . , ~'' ~ . _ _ --~ ~ ~ C ~- In ~n o o ~ ~ . ~ O
T~ ~ ~3 oP H H _ H
_ ' ~ . ,~.
n -o ~ O ~ ~ O o _~
w ro ~ ~D ;
~ 1~ n r~ o o o o ~n ~ r~
~A) ~ (Jl o m O
i~D ~11 D
J' r~
~n ~ ~n ~I ~ ~n ~ o ~n _1 0 o ~ rr O 0 0~ ~ O 1--~ ~ o o o ~n --N ~ (n ~n O O ~n O O O o r-O ~n ~n ~n r ~n O O O O
y ~n W ~ O 1~
~n ~ o o o r,~ o o ~
X O
u~ ~n o o X X ~ o o o o ~ ~ o ~ ~ W o o o ~ ~
o ~n _ ~, r~ ~ o ~
o o o o o ~ .
~D
o o o r,~ r~
~n O
- 30a -
Claims (15)
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 (I) and units of the formula (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 (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 or (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.
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.
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
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 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 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.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DEP4123946.6 | 1991-07-19 | ||
| DE4123946A DE4123946A1 (en) | 1991-07-19 | 1991-07-19 | DENTAL MATERIAL WITH ALUMO ORGANOPOLYSILOXANE FUEL |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2074128A1 CA2074128A1 (en) | 1993-01-20 |
| CA2074128C true CA2074128C (en) | 1998-04-21 |
Family
ID=6436532
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002074128A Expired - Fee Related CA2074128C (en) | 1991-07-19 | 1992-07-17 | Dental material with alumoorganopolysiloxane filler |
Country Status (5)
| Country | Link |
|---|---|
| EP (1) | EP0523545B1 (en) |
| JP (1) | JPH05194136A (en) |
| AT (1) | ATE127008T1 (en) |
| CA (1) | CA2074128C (en) |
| DE (2) | DE4123946A1 (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE19719438C5 (en) * | 1996-05-09 | 2014-05-08 | 3M Deutschland Gmbh | Use of addition-crosslinking polyether impression material for the production of dimensionally stable jaw impressions |
| DE19904816A1 (en) * | 1999-02-05 | 2000-09-14 | Espe Dental Ag | Polymerizable and/or settable dental material, e.g. filling material or cement contains organopolysiloxane particles to allow high overall filler content and give low shrinkage on polymerization |
| CA2687201C (en) | 2007-05-11 | 2016-11-08 | Dentsply International Inc. | Dental compositions for coating restorations and tooth surfaces |
| AT12407U1 (en) | 2010-07-02 | 2012-05-15 | Stephan Lampl | DENTAL FRONT FACING BODY |
Family Cites Families (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS58110414A (en) * | 1981-12-23 | 1983-07-01 | Tokuyama Soda Co Ltd | Inorganic oxide and its manufacture |
| DE3828098A1 (en) * | 1988-08-18 | 1990-03-08 | Fraunhofer Ges Forschung | METHOD AND COMPOSITION FOR THE PRODUCTION OF SCRATCH-RESISTANT MATERIALS |
| DE3903407A1 (en) * | 1989-02-06 | 1990-08-09 | Blendax Werke Schneider Co | DENTAL FUELING MATERIAL |
| CA2010689A1 (en) * | 1989-02-27 | 1990-08-27 | Nobuhiro Mukai | Process for producing powders |
| DE3913252A1 (en) * | 1989-04-22 | 1990-10-25 | Degussa | DENTAL MATERIAL (I) |
| DE3913250A1 (en) * | 1989-04-22 | 1990-10-25 | Degussa | DENTAL MATERIAL (II) |
| DE9103321U1 (en) * | 1991-03-19 | 1992-08-27 | Thera Patent GmbH & Co KG Gesellschaft für industrielle Schutzrechte, 8031 Seefeld | Transparent sealed dental plastic body |
-
1991
- 1991-07-19 DE DE4123946A patent/DE4123946A1/en active Granted
-
1992
- 1992-07-09 DE DE59203443T patent/DE59203443D1/en not_active Expired - Fee Related
- 1992-07-09 AT AT92111661T patent/ATE127008T1/en not_active IP Right Cessation
- 1992-07-09 EP EP92111661A patent/EP0523545B1/en not_active Expired - Lifetime
- 1992-07-17 CA CA002074128A patent/CA2074128C/en not_active Expired - Fee Related
- 1992-07-17 JP JP4190630A patent/JPH05194136A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| JPH05194136A (en) | 1993-08-03 |
| DE59203443D1 (en) | 1995-10-05 |
| EP0523545B1 (en) | 1995-08-30 |
| CA2074128A1 (en) | 1993-01-20 |
| EP0523545A1 (en) | 1993-01-20 |
| ATE127008T1 (en) | 1995-09-15 |
| DE4123946A1 (en) | 1993-01-28 |
| DE4123946C2 (en) | 1993-08-05 |
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| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| MKLA | Lapsed |