Polymerizable dental material

0001The invention describes an improved polymerizable dental material with variably adjustable transparency, good polishability and strength. In particular, the invention relates to a dental material based on a polymerizable, ethylenically unsaturated monomer as a binder, a catalyst for cold, hot and / or photopolymerization and an inorganic filler consisting of a mixture of<ul id="ul0001" list-style="none" compact="compact"><li>A) spherical on SiO₂ based particles with</li><li>B) aspherical, splinter-shaped powders made of quartz, glass ceramic and / or glass with a refractive index of 1.50 to 1.58 and an average particle size of 0.5 to 5.0 µm</li></ul> consists.

0002The following publications are mentioned in relation to the prior art:<ul id="ul0002" list-style="none" compact="compact"><li>(1) DE-A 32 47 800</li><li>(2) DE-A 39 03 407</li><li>(3) EP-A 0 238 025</li><li>(4) US-A 4,503,169 or EP-A 0 159 887</li><li>(5) EP-A 0 530 926</li><li>(6) DE-A 40 29 230</li></ul><ul id="ul0003" list-style="none"><li>(1) relates to amorphous, spherical particles, processes for their preparation and their use in dental materials. Inorganic compounds with a particle size of 0.1 to 1.0 μm are disclosed which contain as main constituents an oxide of at least one metal from group I, II, III or IV of the periodic table which is capable of binding with silicon dioxide and silicon dioxide. The amorphous particles are e.g. B. made from the melt or by a sol-gel process. This results in mixed oxides whose refractive indices are in the range from 1.35 to 1.70. In the dental materials, which contain such a filler, possibly in a mixture with a polymer filler, the particles should not agglomerate, as a result of which the filling ratio is increased and the mechanical strength and the surface of the dental composite material obtained are increased. The transparency and surface smoothness of the dental materials should also be improved. Although such dental materials can convince in terms of some processing properties, their mechanical strength is still in need of improvement.</li><li>From (2) organically modified silica compounds are known as dental fillers. These are inorganic-organic polymers that are referred to as "ORMOCERe" or "ORMOSILe". These silicone-like polymers are produced by a sol-gel process in the presence of acidic or basic catalysts. The ORMOCER fillers are suitable as the sole fillers of dental filling materials or for combination with other components, such as. B. silanized silicon dioxide, boron and barium silicate glasses, aluminum silicate or glass ceramic fillers. They are through a surface of 10 to 50 m²/ g characterized, there is no characterization with regard to particle size or refractive index. Some of the silicon atoms in the ORMOCER structure can be replaced by titanium or zirconium atoms. ORMOCERs are a new class of composite materials, whereby the name ORMOCER is an abbreviation for ORganically MOdified CERamics. The ORMOCERe consist of atomic ceramic and plastic networks that connect and penetrate each other. A disadvantage of the use of ORMOCERs or ORMOSILs in filler mixtures for dental materials is, however, that the ORMOSILs described do not result in transparent materials, which makes their suitability altogether questionable.</li><li>(3) has the object of X-ray-opaque polymerizable dental compositions which, in addition to one or more ethylenically unsaturated polymerizable monomers and / or polymers and, if appropriate, customary fillers, pigments and other auxiliaries, contain a difficultly soluble complex heavy metal fluoride. It is pointed out that the transparency of the polymerized masses strongly depends on the ratio of the refractive indices of the packing and the polymeric matrix, differences in the refractive indices of polymer and monomer being regarded as small if they are in the range from 1.45 to 1.6 lie. The fillers known from (3) are all in the form of aspherical splinters, which leads to inadequate polishability of the hardened compositions when using the dental compositions disclosed in (3).</li><li>According to (4), composites are known which contain, as filler, certain non-glass microparticles which are essentially free of opaque inclusions. This is preferably SiO₂/ ZrO₂Fillers with a diameter &lt;50 µm. The microparticles have a large number of amorphous and crystalline micro-regions, the amorphous regions containing silicon dioxide and the crystalline regions containing a radiopaque, ceramic metal oxide. The oxides of elements from, for example, the second to fifth main group and the third to fifth subgroup of the periodic table and oxides of lanthanides are suitable. Preferred ceramic metal oxides are HfO₂, La₂O₃, SrO and ZrO₂. The microparticles are preferably produced by a sol-gel process. The refractive indices of filler and composite plastic should correspond to compositions curable by visible light. Deviations of 0.05 or 0.005 are aimed for. The refractive index of the microparticles can be adjusted by changing the ratio of silicon dioxide to the oxide of the ceramic metal. The fillers described in (4) can be filled with micro-fillers such as. B. AEROSIL can be used together. On the one hand, the importance of matching refractive indices of filler and composite plastic follows from (4), but at the same time amorphous silica, which is known to aggregate, is added in larger quantities as a so-called microfiller.</li><li>(5) discloses dental compositions composed of a polymerizable monomer and an inorganic filler, which consists of 20 to 80% by weight of spherical inorganic oxide particles with an average particle size between 1.0 and 5.0 µm and 80 to 20% by weight spherical inorganic oxide particles with a particle size in the range of at least 0.05 microns and less than 1.0 microns, with at least 5 wt .-% of the latter component in the range of 0.05 to 0.2 microns. The inorganic particles are exclusively spherical particles of inorganic oxides of silicon, zirconium, aluminum and titanium or mixed oxides of metals from the I - IV main group of the periodic table with silicon. The spherical particles are e.g. B. prepared by hydrolytic polymerization of alkoxysilanes and can, for. B. can also be surface-treated with γ-methacryloxypropyltrimethoxysilane. A disadvantage of the fillers having only spherical particles, as in (1), is an inadequate strength of the resulting dental materials.</li><li>From (6) an improved dental material based on a polymerizable, ethylenically unsaturated monomer as a binder and a catalyst for cold, hot and / or photopolymerization is known which contains 20 to 90% by weight of a mixture of inorganic fillers<ul id="ul0004" list-style="none" compact="compact"><li>(A) amorphous, spherical particles of silicon dioxide and up to 20 mol% of an oxide of at least one element from groups I, II, III and IV of the periodic table with a refractive index of 1.50 to 1.58 and with an average primary particle size of 0 , 1 to 1.0 µm, and</li><li>(B) quartz, glass ceramic or glass powder or mixtures thereof with a refractive index of 1.50 to 1.58 and with an average primary particle size of 0.5 to 5.0 µm</li></ul> and possibly small amounts of other fillers to increase the opacity and adjust the viscosity.</li></ul>

0003Although the dental materials according to (6) should have good transparency and polishability as well as other good material properties such as compressive strength, abrasion resistance and flexural strength, it was found during reworking that the disclosed SiO₂Particle mixed oxides require a complex manufacturing process and the compressive strength of the dental material shown cannot meet the requirements.

0004In view of the state of the art specified and discussed herein, it was an object of the invention to provide an improved dental material which meets all the requirements placed on a modern dental material in terms of transparency, polishability, pressure resistance, water absorption, abrasion resistance, flexural strength, X-ray opacity, etc., which is easy to produce and is easily adaptable to certain special requirements.

0005This object is achieved by a dental material of the type mentioned at the beginning with the features of the characterizing part of claim 1.

0006Appropriate further training is protected under the dependent claims.

0007Characterized in that the amount of the filler is 1-95% by weight, based on the dental material, and in that, as component A), it has spherical particles present separately in the fully polymerized dental material<ul id="ul0005" list-style="none" compact="compact"><li>A1) SiO₂ with a refractive index of between approximately 1.38 and &lt;1.50 and an average primary particle size of approximately 0.04 µm to 1.5 µm,</li><li>A2) an SiO₂Core which is coated with an oxide of at least one element from groups I, II, III and IV of the periodic table, the coated particles having a refractive index of 1.45 to 1.62 and an average primary particle size of 0.04 to 1.5 Have µm and the coating is between about 15 and 40 nm thick, and / or</li><li>A3) particles described under A1) or A2), which are additionally coated with a layer of a polymerizable organic binder which is based on mono- or polyfunctional (meth) acrylates and / or reaction products of isocyanates and OH group-containing methacrylates, the primary particle size of the particles provided with polymerizable binder layer between approx. 0.04 and 1.5 µm, while the layer thickness of the coating layer is in the range of 5 nm to 50 nm and the refractive index of the coated particles is in the range of 1.40-1.52,</li></ul> It is possible to create a polymerizable dental material with variably adjustable transparency, good polishability and high strength, which was particularly surprising that the measures described under A1) to A3) succeeded in avoiding the formation of aggregates of the primary particles. In particular, the inventive filler combinations of spherical, separately present particles on SiO₂-Base and irregularly shaped splinter-shaped particles enables high degrees of space filling, because the smaller spherical particles do not aggregate and thus the spaces between the larger particles are filled to the maximum. As a result, these so-called gussets are optimally filled with individual balls, a drop in compressive strength resulting from the formation of an aggregate being avoided. This was all the more surprising than the spherical mixed oxide SiO₂-Primary particles in the fully polymerized dental material according to the prior art (document (6)) are not present in isolation but bake together to form larger agglomerates, so that the primary particle size of the particles does not correspond to the actual particle size in the finished dental material. This can e.g. B. by means of SEM images and obviously leads to reduced strength values, especially the compressive strength of dental materials according to the prior art.

0008In the context of the invention, dental material refers to materials for tooth filling, inlays or onlays, dental cements, veneering materials for crowns and bridges, materials for artificial teeth or other materials for prosthetic, preservative and preventive dentistry. In particular, the term dental material also includes composites for dental and dental technical uses, sealant materials, self-curing composites, die build-up materials, veneering plastics, highly and normally filled dual cements as well as normally filled fluoride-containing dental lacquers.

0009Suitable binders for the dental material are all those binders based on a polymerizable, ethylenically unsaturated monomer which are known to the person skilled in the art for this purpose. The polymerizable monomers that can be used successfully include those with acrylic and / or methyacrylic groups.

0010In particular, these include esters of α-cyanoacrylic acid, (meth) acrylic acid, urethane (meth) acrylic acid, crotonic acid, cinnamic acid, sorbic acid, maleic acid and itaconic acid with mono- or dihydric alcohols; (Meth) acrylamides such as e.g. B. N-isobutylacrylamide; Vinyl esters of carboxylic acids such as B. vinyl acetate; Vinyl ethers such as B. butyl vinyl ether; Mono-N-vinyl compounds such as N-vinylpyrrolidone; and styrene and its derivatives. The mono- and polyfunctional (meth) acrylic esters and urethane (meth) acrylic esters listed below are particularly preferred.<ul id="ul0006" list-style="none"><li>(a) Monofunctional (meth) acrylates Methyl (meth) acrylate, N- or i-propyl (meth) acrylate, n-, i- or tert-butyl (meth) acrylate and 2-hydroxyethyl (meth) acrylate.</li><li>(b) Difunctional (meth) acrylates Compounds of the general formula:<chemistry id="chem0001" num="0001"><img file="EP0732099A2_D0001.tif" /></chemistry> wherein R is hydrogen or methyl and n is a positive integer between 3 and 20, such as. B. Di (meth) acrylate of propanediol, butanediol, hexanediol, octanediol, nonanediol, decanediol and eicosanediol, compounds of the general formula:<chemistry id="chem0002" num="0002"><img file="EP0732099A2_D0002.tif" /></chemistry> wherein R is hydrogen or methyl and n is a positive integer between 1 and 14, such as. B. Di (meth) acrylate of ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, dodecaethylene glycol, tetradecaethylene glycol, propylene glycol, dipropyl glycol and tetradecapropylene glycol; and glycerol di (meth) acrylate, 2,2'-bis [p- (γ-methacryloxy-β-hydroxypropoxy) phenylpropane] or bis-GMA, biphenol A dimethacrylate, neopentyl glycol di (meth) acrylate, 2,2'- Di (4-methacryloxypolyethoxyphenyl) propane with 2 to 10 ethoxy groups per molecule and 1,2-bis (3-methacryloxy-2-hydroxypropoxy) butane.</li><li>(c) Trifunctional or multifunctional (meth) acrylates Trimethylolpropane tri (meth) acrylates and pentaerythritol tetra (meth) acrylate.</li><li>(d) urethane (meth) acrylate Reaction products of 2 moles of hydroxyl-containing (meth) acrylate monomer with one mole of diisocyanate and reaction products of a urethane prepolymer having two NCO end groups with a methacrylic monomer which has a hydroxyl group, as described, for. B. are represented by the general formula:<chemistry id="chem0003" num="0003"><img file="EP0732099A2_D0003.tif" /></chemistry> wherein R represents hydrogen or a methyl group, R₂ an alkylene group and R₃ embodies an organic residue.</li></ul>

0011The monomers mentioned are used either alone or in the form of a mixture of several monomers.

0012The particularly advantageous monomers used in the dental material according to the invention include, in particular, 2,2-bis-4 (3-methacryloxy-2-hydroxypropoxy) phenylpropane (bis-GMA), 3,6-dioxaoctamethylene dimethacrylate (TEDMA) and / or 7.7 , 9-Trimethyl-4,13-dioxo-3,14-dioxa-5,12-diazahexadecane-1,16-dioxy-dimethacrylate (UDMA).

0013Depending on the type of catalyst used, the dental material can be hot, cold and / or polymerizable by light. The known peroxides such as dibenzoyl peroxide, dilauroyl peroxide, tert-butyl peroctoate or tert-butyl perbenzoate can be used as catalysts for the hot polymerization, but also α, α'-azobis (isobutyroethyl ester), benzpinacol and 2,2'-dimethylbenzpinacol are suitable

0014As catalysts for photopolymerization such. B. benzophenone and its derivatives and benzoin and its derivatives can be used. Further preferred photosensitizers are α-diketones such as 9,10-phenanthrenequinone, diacetyl, furil, anisil, 4,4'-dichlorobenzil and 4,4'-dialkoxybenzil, camphorquinone is particularly preferably used. The use of the photosensitizers together with a reducing agent is preferred. Examples of reducing agents are amines such as cyanoethylmethylaniline, dimethylaminoethyl methacrylate, triethylamine, triethanolamine, N, N-dimethylaniline, N-methyldiphenylamine, N, N-dimethyl-sym.-xylidine and N, N-3,5-tetramethylaniline and 4-dimethylaminobenzoic acid ethyl ester.

0015As catalysts for cold polymerization, radical-supplying systems, e.g. B. benzoyl or lauroyl peroxide together with amines such as N, N-dimethyl-sym.-xylidine or N, N-dimethyl-p-toluidine. Dual curing systems for catalysis can also be used, e.g. B. Photoinitiators with amines and peroxides. Mixtures of UV-light-curing and visible-light-curing catalysts are also suitable as photocatalysts.

0016The amount of these catalysts in the dental material is usually between 0.01 and 5% by weight.

0017The dental material according to the invention preferably serves as tooth filling material. Tooth filling materials are also produced as two-component materials that harden cold after mixing. The composition is similar to that of the light-curing materials, only a paste is used instead of the photocatalysts. B. benzoyl peroxide and in the other paste z. B. N, N-dimethyl-p-toluidine incorporated. By mixing approximately the same parts of the two pastes, a tooth filling material is obtained which hardens in a few minutes.

0018If you omit the amine in the latter materials and as a catalyst z. B. only uses benzoyl peroxide, a hot-curing dental material is obtained, which can be used for the production of an inlay or artificial teeth. For the production of an inlay, an impression is taken from the cavity in the patient's mouth and a plaster model is made. The paste is placed in the cavity of the plaster model and the whole is polymerized in a pressure pot under heat. The inlay is removed, processed and then cemented into the cavity in the patient's mouth.

0019The dental materials according to the invention owe their outstanding properties primarily to the type of fillers A) used and the well-balanced coordination of the proportion of spherical fillers A) to splinter-shaped filler particles B). The ratio A) to B) is important for the strength of the polymerized dental material.

0020Variants A1) to A3) or mixtures of these types are suitable as fillers A).

0021Components A1) to A3) each solve the problem on which the invention is based, but what they have in common is that all types are based on SiO₂ are based or consist exclusively of them and, furthermore, all components A1) to A3) are not present as agglomerate but as separate particles in the polymerized dental material.

0022According to the invention, A1) SiO₂-Particles with a refractive index of between 1.38 and &lt;1.50 with an average primary particle size of approximately 0.04 µm to approximately 1.5 µm are used as component A).

0023Surprisingly, when using pure SiO₂-Particles contrary to the view prevailing in the literature (cf. 6), a dental material for fillings of excellent tooth-like transparency can be obtained. Since the light scattering depends on the size of the embedded particles, when using the smallest particles, preferably with diameters in the nm range that do not aggregate, a particle distribution is achieved due to which the light scattering is so low that transparent materials are obtained.

0024In a preferred embodiment according to the invention, the pure SiO₂Particles have an average particle diameter of approximately 0.04 µm to approximately 0.25 µm. This particular size is particularly suitable in dental materials, which are used especially with restorative materials, veneering materials or artificial teeth.

0025In particular for these applications as well, it is particularly expedient that the average particle size of the pure SiO₂-The total particle size is not larger than 0.1 µm.

0026Where the transparency of the material is of minor importance (for example in the case of core build-up materials, cements for fastening, sealers and the like), particle sizes of 0.25 µm to 1.5 µm are also preferred. The particles are then particularly advantageously in a size of 0.25 to 1.0 μm.

0027The pure SiO to be used according to the invention₂-Particles are preferably monodisperse, non-porous and essentially spherical. Basically, all oxide particles are suitable which can be obtained by hydrolytic polycondensation from alcoholate compounds of corresponding elements and which are obtained in the form of monodisperse, compact spherical particles. The basic reaction conditions for the production of SiO₂Particles by hydrolytic polycondensation are, for example, from the publications W. Stöber et al. in J. Colloid and Interface Science 26, 62 (1968) and 30, 568 (1969) and U.S. Patent 3,634,588.

0028For the production of highly monodisperse, non-porous, spherical SiO₂Particles which have a standard deviation of not more than 5% are referred to EP 0 216 278, which discloses a correspondingly stopped manufacturing process based on hydrolytic polycondensation. The core of this process, which is used to manufacture SiO₂-Particle preferred according to the present invention is a two-step procedure. Here, a sol or a suspension of primary particles is first formed by hydrolytic polycondensation of tetraalkoxysilanes in an aqueous alkaline-ammoniacal medium, which is then brought to the desired final size by metered addition of further tetralkoxysilane.

0029A similar process for producing various metal oxides in the form of spherical particles with a narrow particle size distribution can also be found in EP 0 275 688.

0030In the context of the invention, the fillers of type A2) are layer-shaped particles which contain an SiO₂Have core, which is coated with an oxide of at least one element from groups I, II, III and IV of the periodic table.

0031Here, the SiO used as the core₂-Particles basically with the pure SiO described under A1)₂-Particles are identical, but as a rule it has a particle size reduced by the thickness of the coating as the starting product. It should be emphasized that the particles of type A2) are not present according to the invention as mixed oxide particles, but rather the SiO₂Core is surrounded by a corresponding other oxide of at least one element from groups I to IV of the periodic table. It has surprisingly been found that, in contrast to the mixed oxides, the coated particles are generally present separately and in particular not in the form of aggregates in the polymerized dental material. The coated particles of type 2 can basically be produced in analogy to the two-stage processes described under A1) herein. In the hydrolytic polycondensation of tetralkoxysilane, a sol or a suspension of primary particles is formed in aqueous-alkaline-ammoniacal medium, which is then brought to the desired final size by metered addition of another tetraalkoxysilane. A primary particle is thus formed from an oxide, onto which another oxide or an oxide mixture is then deposited in the growth step. This advantageously allows the resulting refractive index to be varied. If the amount of oxide formed in the growth step outweighed the finished particle, it would be essentially responsible for the resulting refractive index. Among the most preferred on the SiO₂Core-deposited oxidic compounds of groups I to IV of the periodic table include TiO₂, ZrO₂, Al₂O₃ and / or V₂O₅. Here is TiO₂ very particularly preferred, it being important when using it that the TiO₂ is completely bound, otherwise the dental material may yellowish. In addition to the preferred compounds from groups I to IV of the periodic table, other compounds are also possible. So you can also with advantage Nb₂O₅ or mixed systems with the aforementioned oxides from groups I to IV of the periodic table with success on SiO₂- Separate primary particles.

0032According to the invention, the particles described under A1) or A2) can additionally be coated with a layer of a polymerizable organic binder (A3)) which is based on mono- or polyfunctional methacrylates and / or reaction products made from isocyanates and OH group-containing methacrylates. An organic modification of the particles on the surface, which may be advantageous for the respective application, is thus possible. This can be carried out in complete agreement with methods known for the preparation of silica gels commonly used as chromatographic sorbents. Common modifiers are Organotrialkoxysilande, such as. B. Methyltriethoxysilane, ethyltriethoxysilane, octyltriethyoxysilane, octadecyltriethoxysilane, mono- or polyfluoroalkylethoxysilane or also silanes with functionalized organo groups, which enable subsequent further modification by covalent bond formation in a known manner. In the latter case, organotrialkoxysilanes of this type are preferred with regard to the use according to the invention of the particles as fillers in polymeric or polymerizable systems which have functional groups with which covalent integration into the polymer material can be achieved. Examples of these are trimethoxyvinylsilane, triethoxyvinylsilane and 3-glycidoxypropyltrimethoxysilane, and also silanes with inorganic radicals carrying hydroxyl, carboxyl, epoxy and carboxylic acid ester groups. The incorporation of such modified particles according to A3) into the dental material is done by incorporating the particles into the dental material and subsequent polymerization during the actual curing of the dental material.

0033Alternatively, it is also possible to polymerize the surface-modified particles according to A1) or A2) before the actual incorporation into the dental material. This can be done, for example, in accordance with a method described in the Journal of Colloid and Interface Science 160, 298-303 (1993). In any case, a fine gradation and regulation of the refractive index of the entire dental material can be achieved by suitable matching of the monomer used for surface modification to the monomer or the monomer mixture which forms the polymer matrix of the dental material.

0034The inorganic filler (B) of the filler mixture is quartz, glass ceramic or glass powder. Glasses are preferably used. The average primary particle size of the inorganic filler (B) should be between 0.5 and 5.0 μm, in particular between 1.0 and 2.0 μm and particularly preferably between 1.0 and 1.5 μm, while the refractive index is between 1 , 50 and 1.58, in particular between 1.52 and 1.56. Filler mixtures can also be used.

0035According to the invention, preference is given to Ba silicate glasses with an average grain size in the range from 1.1 to 1.3 μm, and Sr silicate glasses with an average grain size in the range from 1.1 to 1.3 μm, and Li / Al silicate glasses with a average grain size of 1.0 to 1.6 microns used. Such powders can e.g. B. obtained by fine grinding with a conventional ultrafine mill.

0036Polysiloxane fillers which contain aluminum and consist of units of the formula are also suitable as splinter-shaped fillers of type (B)<chemistry id="chem0004" num="0004"><img file="EP0732099A2_D0004.tif" /></chemistry> and units of the formula<chemistry id="chem0005" num="0005"><img file="EP0732099A2_D0005.tif" /></chemistry> where R¹ for a linear or branched alkyl group with 1 to 6 C atoms connected with an acrylate or methacrylate residue or for a simple olefinically unsaturated linear or branched hydrocarbon residue with 2 to 8 C atoms or for a cyclic, single olefinically unsaturated hydrocarbon residue with 5 - 8 C atoms or for a linear or branched alkyl group with 1 to 8 C atoms, a cycloalkylene group with 5 to 8 C atoms, is a phenyl group or an alkylaryl group, and / or units of the formula<chemistry id="chem0006" num="0006"><img file="EP0732099A2_D0006.tif" /></chemistry> in which R² represents a methyl, ethyl, propyl or phenyl group, and - in each of the compositions - units of the formula<chemistry id="chem0007" num="0007"><img file="EP0732099A2_D0007.tif" /></chemistry> in which R³ is a linear or branched alkyl group with 1 to 5 carbon atoms or a phenyl group, and the free valences of the oxygen atoms bonded to the silicon and aluminum atoms in units (I), (II) and / or (III) and (IV ) are saturated by a silicon atom of the same or a different unit or by an aluminum atom, as in the case of heterosiloxane skeletons, 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) 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 units (IV) is 2: 1 to 200: 1.

0037The aluminum in the polysiloxane filler may also be replaced by another metal.

0038If necessary, further fillers (C) can be used to achieve increased X-ray opacity, the mean primary particle size of which should not exceed 5.0 μm. Such fillers are e.g. B. described in DE-OS 35 02 594.

0039If necessary, small amounts of microfine, pyrogenic or wet-precipitated silica (filler (D)) can be incorporated into the dental material to adjust the viscosity, but at most 5% by weight, based on the dental material.

0040In a preferred embodiment of the invention, the dental material is characterized in that the proportion by weight of filler (A) is 1-60% by weight and that of filler (B) is 15-85% by weight, with both% by weight details being in each case the total weight of the dental material is related. By choosing the amounts of fillers in this area, it is particularly advantageous to optimize the ratio of type B splinter-shaped constituents to type A spherical, separate particles.

0041It is furthermore expedient to set the ratio of filler A) to filler B) in the finished dental material in such a way that aggregate formation of the fillers (A) is avoided. The person skilled in the art can determine this empirically by means of appropriate tests.

0042In a particularly preferred embodiment, the ratio of the filler components (A) to the fillers (B) is set in the range from 1:85 to 4: 1 (in each case based on% by weight) such that the strength of the resulting dental material is based on its compressive strength is in the range from> 320 to approx. 480 MPa. It has proven to be particularly favorable here if the ratio of fillers A) to fillers B) ≧ 1:10 (in each case based on% by weight).

0043The invention is explained in more detail below on the basis of exemplary embodiments and comparative examples.

Examples

0044A commercial kneader from Grieser was used to produce the pastes described below. His kneading tools were modified so that a particularly intensive mixing and homogeneous distribution of the starting materials was possible. The monomer mixtures were usually homogenized using a three-roll mill.

0045In the case of light-curing systems, the curing time was 40 seconds using a commercially available lamp (Degulux® from Degussa).

Method description:

Transparency:

0046The transparency is determined on test specimens with a thickness of d = 3 ± 0.1 mm and a diameter of 20 ± 0.1 mm. To produce the samples, the composite paste filled into the steel molds of the same dimensions is loaded with 4000 kp for 30 seconds and then for 2 minutes with a dental lamp with a light intensity of at least 250 rel. Units cured. During the curing process, the composite surface is shielded from atmospheric oxygen by a transparent polyester film. The transparency is measured with a UV / VIS spectrophotometer PU8800 (Philips) in transmission mode.

Compressive strength:

0047The composite is blister-free in a Duran glass tube with a height of h = 9 mm and a diameter of d = 4 mm and for 40 seconds with a dental lamp with a light intensity of at least 250 rel. Units cured. After removal from the mold, the test specimen is shortened to 6.0 mm with a diamond saw and stored for 24 hours in distilled water at 37 degrees Celsius. The pressure resistance is measured with a universal testing machine from Frank. The numerical values ​​are based on mean values ​​from 7 individual measurements.

0048In the examples below, fillers A1, A2 and A3 are used as follows: A1: amorphous SiO₂Particles with a diameter of 80-1000 nm, refractive index approx. 1.4; A2: SiO₂Core of 500nm + 30nm thick layer of TiO₂, Refractive index 1.49; A3: SiO core of 500nm + 50nm thick layer of bis-GMA, refractive index 1.47.

Example 1:

0049In 22.86 g of a monomer mixture consisting of 45 parts of Bis-GMA, 20 parts of UDMA and 35 parts of TEDMA, 71.14 g of silanized barium silicate glass, 5 g of Aerosil and 1 g of the spherical, monodisperse and non-aggregated filler A1, particle diameter 500, are present nm incorporated together with 0.038% by weight camphorquinone. The resulting paste was cured with light (Degulux®). Transparency: 21.7%

Example 2:

0050as example 1, but the particle diameter of the filler A1 is 100 nm. Transparency: 33.4%

Example 3:

005165 g of silanized barium silicate glass, 5 g of Aerosil and 9 g of the monodisperse filler A1, particle diameter 100 nm, together with 0.038% by weight of camphorquinone are incorporated into 21 g of a monomer mixture analogous to Example 1. The resulting paste was cured with light (Degulux®). Transparency: 20.3%

Example 4:

0052as example 3, but the particle diameter of the filler A1 is 80 nm. Transparency: 24.1%

Example 5:

0053In 18.2 g of a monomer mixture consisting of 20 parts of Bis-GMA, 55 parts of UDMA and 25 parts of TEDMA, 64 g of silanized Ba silicate glass, 10.7 g of silanized Aerosil and 7.1 g of filler A1 with a diameter of 1000 nm are combined with 0.038% by weight camphorquinone incorporated. A smooth material is created. Transparency: 11.9%

Example 6:

005469 g of silanized barium silicate glass, 5 g of Aerosil and 5 g of the spherical, monodisperse and non-aggregated filler A1, particle diameter 95 nm, together with 0.038% by weight of camphorquinone are incorporated into 21 g of a monomer mixture analogous to Example 1. After adding pigments, the paste has a tooth-colored appearance. The resulting paste was cured with light (Degulux®). The material obtained is suitable as a light-curing, tooth-colored filling material for the anterior and posterior region and as a material for inlays and onlays. Transparency: 23.0% Compressive strength: 420 MPa

Comparative Example 7:

0055In 17.3 g of a monomer mixture consisting of 42.2 parts of Bis-GMA, 36.4 parts of UDMA and 21.4 parts of TEDMA, 46.8 g of barium silicate glass, 3.8 g of Aerosil and 15.4 g of ytterbium (III) are fluoride and 16.5 g of spherical filler according to DE 4029230 A1. In addition, small amounts of color pigment were added Transparency: 21.0% Compressive strength: 300 MPa

Example 8:

Base paste:

0056In 22.4g of a monomer mixture consisting of 54.9 parts UDMA, 20.1 parts Bis-GMA and 25 parts TEDMA are 59.5g silanized barium silicate glass, 7.2g Aerosil, 0.5g activator / stabilizer and 10.4g Filler A1 or A2 or A3 or combinations thereof incorporated. After adding a small amount of pigments, a highly viscous, tooth-colored paste is created

Catalyst paste:

0057In 22.4g of a monomer mixture consisting of 54.9 parts UDMA, 20.1 parts Bis-GMA and 25 parts TEDMA are 59.5g silanized barium silicate glass, 7.2g Aerosil, 0.5g benzoyl peroxide and 10.4g filler A1 or A2 or A3 or combinations thereof. After adding a small amount of pigments, a highly viscous, tooth-colored paste is formed, which, after mixing with equal parts of base paste, is suitable as a self-curing filling material or for the production of heat-curing inlays. Transparency: 21.2%

Example 9:

Base paste:

0058In 30g of a monomer mixture consisting of 28.9 parts TEDMA and 71.1 parts UDMA are 59g silanized barium silicate glass, 6g of the spherical filler A1 and 5g silanized Aerosil together with 1.15% of an activator / stabilizer mixture and 0.09% champagne quinone incorporated. After adding small amounts of pigments, a tooth-colored, viscous paste is created.

Catalyst paste:

0059In 30g of a monomer mixture consisting of 28.9 parts of TEDMA and 71.1 parts of UDMA, 59g of silanized barium silicate glass, 6g of the spherical filler A1 and 5g of silanized Aerosil are incorporated together with 0.6% benzoyl peroxide. After adding small amounts of pigments, a tooth-colored, viscous paste is created.

0060After mixing both pastes, a light and self-curing dental cement paste is created. Transparency: 22.0%

Example 10:

0061In 96g of a monomer mixture consisting of 60 parts of Bis-GMA and 40 parts of TEDMA, 3g of the spherical, monodisperse filler A1 and 1g of titanium dioxide present separately in the material are incorporated together with 0.12% camphorquinone. The result is a white, thin-flowing material that has no sedimentation of the fillers after one year of storage. The dental material obtained is suitable for sealing fissures and tooth surfaces. Transparency: 30.3% (layer thickness = 0.5mm)