Classifications

• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
  • C04B35/622—Forming processes; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
  • C04B35/626—Preparing or treating the powders individually or as batches ; preparing or treating macroscopic reinforcing agents for ceramic products, e.g. fibres; mechanical aspects section B
  • C04B35/62605—Treating the starting powders individually or as mixtures
  • C04B35/62645—Thermal treatment of powders or mixtures thereof other than sintering
  • C04B35/62665—Flame, plasma or melting treatment
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
  • A61K6/00—Preparations for dentistry
  • A61K6/15—Compositions characterised by their physical properties
  • A61K6/16—Refractive index
• • 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
  • A61K6/802—Preparations for artificial teeth, for filling teeth or for capping teeth comprising ceramics
  • A61K6/822—Preparations for artificial teeth, for filling teeth or for capping teeth comprising ceramics comprising rare earth metal oxides
• • 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
  • A61K6/802—Preparations for artificial teeth, for filling teeth or for capping teeth comprising ceramics
  • A61K6/824—Preparations for artificial teeth, for filling teeth or for capping teeth comprising ceramics comprising transition metal oxides
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
  • C04B35/01—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics
  • C04B35/14—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on silica
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
  • C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
  • C04B2235/30—Constituents and secondary phases not being of a fibrous nature
  • C04B2235/32—Metal oxides, mixed metal oxides, or oxide-forming salts thereof, e.g. carbonates, nitrates, (oxy)hydroxides, chlorides
  • C04B2235/3224—Rare earth oxide or oxide forming salts thereof, e.g. scandium oxide
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
  • C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
  • C04B2235/30—Constituents and secondary phases not being of a fibrous nature
  • C04B2235/44—Metal salt constituents or additives chosen for the nature of the anions, e.g. hydrides or acetylacetonate
  • C04B2235/449—Organic acids, e.g. EDTA, citrate, acetate, oxalate
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
  • C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
  • C04B2235/50—Constituents or additives of the starting mixture chosen for their shape or used because of their shape or their physical appearance
  • C04B2235/52—Constituents or additives characterised by their shapes
  • C04B2235/528—Spheres
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
  • C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
  • C04B2235/50—Constituents or additives of the starting mixture chosen for their shape or used because of their shape or their physical appearance
  • C04B2235/54—Particle size related information
  • C04B2235/5409—Particle size related information expressed by specific surface values

Definitions

• the present invention relates to the use of at least one nanoparticulate mixed oxide (a) of SiO 2 produced by spray flame synthesis with X-ray-opaque metal oxides of one or more elements selected from the group consisting of Y, La, Ta, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, as an X-ray-opaque filler in dental composites, the resulting dental composites, their production and use.
• a nanoparticulate mixed oxide (a) of SiO 2 produced by spray flame synthesis with X-ray-opaque metal oxides of one or more elements selected from the group consisting of Y, La, Ta, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu
• Amorphous are homogeneous, non-crystalline solids in which the molecular
• a homogeneous element distribution is understood to mean that the elements are mixed uniformly with one another, i.e. that there is essentially a statistical distribution of the elements, without areas with accumulations of a single element. Accordingly, there is a uniform distribution of the elements in the corresponding particles, which does not change in different areas of the particles, that is to say there are no concentration gradients of the elements within the respective particles.
• variable means that the x-ray opacity can be set within certain limits by the person skilled in the art in a familiar manner within the limits of the parameters in the production of the mixed oxides, that is to say by means of starting materials, concentration, temperature and others.
• the X-ray opacity of the composites based on the mixed oxides according to the invention can be set between 50% Al and 800% Al, in particular between 100% Al and 400% Al.
• variable means that the refractive index is determined by the parameters in the production of the mixed oxides, i.e. That is, it can be adjusted in a familiar manner by the skilled person within certain limits using educts, concentration, temperature, etc.
• the refractive index of the mixed oxides according to the invention can be set between 1.46 and 1.70, in particular between 1.48 and 1.60.
• spherical means that the primary particles in question are spheroid and, in transmission electron microscopy (TEM), show no preferred direction or edges comparable to ideal spheres.
• TEM transmission electron microscopy
• (meth) acrylic is intended to include both methacrylic and acrylic in the context of the present invention.
• Composites are used in dentistry primarily as a direct filling material for cavities, as a fastening cement or as a material for inlays or veneering materials. They are basically made up of an organic monomer or polymer matrix and fillers embedded in it.
• the organic resin matrix of the current dental filling composites is largely based on dimethacrylates such as bis-GMA (an addition product from methacrylic acid and bisphenol-A-diglycidyl ether), UDMA (an addition product from 2-hydroxyethyl methacrylate and 2,2,4-hexamethylene diisocyanate) or TEGDMA (triethylene glycol) dimethyl ,
• the fillers are mostly silicate in nature, whereby for an optimal bond between the resin matrix and the filler particles, these are surface-treated with a polymerizable silane.
• the fillers ensure adequate mechanical properties, such as high compressive and flexural strength or hardness, and a low coefficient of thermal expansion as well as a reduction in heat generation and volume contraction during curing, as well as the adjustment of the optical properties and the X-ray opacity (EC Combe, FJT Burke, WH Douglas, Dental Biomaterials, Kluwer Academic Publ., Boston 1999, p. 237).
• the X-ray opacity is achieved above all by incorporating elements with a high atomic number (eg Ba or Sr) in the fillers.
• the refractive index of the glass fillers can be varied within a wide range (1.46 to 1.55)
• the nanofillers used so far are based essentially on silicon dioxide (SiO 2 ), whereby the refractive index is restricted to a range from 1.42 to 1.49.
• An optimal match of the refractive index of filler and polymerized matrix is a prerequisite for a high transparency of the composites and thus the basis for aesthetic restorations.
• a wide refractive index range (1.45 to 1.55) of the polymerized matrix can be set, the most reactive monomers, such as Bis-GMA, are aromatic in nature with a refractive index of approx. 1.55.
• Monomers with a refractive index of 1.52 to 1.55 are preferred according to the invention.
• the x-ray opacity of silicon oxide is very low, so that a composite based on this filler has only a weak x-ray opacity, which makes dental diagnostics difficult.
• X-ray opaque fillers such as ytterbium fluoride or X-ray opaque glasses have a significantly higher refractive index (1.51 to 1.55) than SiO 2 .
• X-ray-opaque metal oxide fillers suitable for dental composites are known from the following prior art: Amorphous, spherical inorganic compounds with a particle size of (0.1 to 1.0 ⁇ m) based on SiO 2 and at least one oxide of the elements of I. to IV. Group, which are prepared by a wet chemical synthesis are described in DE 3247800. Dental composites based thereon are contained in DE 40 29 230.
• DE 195 08 586 describes fillers which, starting from an SiO 2 core, are coated with an oxide of an element from the I to IV group Sol. Gel-chemical can be obtained. Such fillers are also mentioned in DE 197 41 286.
• Polymerizable metal oxide particles which have a core-shell structure are disclosed in DE 198 46 660. Such fillers are accessible by surface modification of, for example, commercially available SiO 2 particles with metal alkoxides.
• EP 1 243 552 describes oxide particles which are suitable as fillers for dental materials, with a core made of any metal or metalloid oxide of the periodic table, any doping component distributed in the core and a shell surrounding the core. These particles are produced in such a way that the doping is first introduced in a pyrogenic process via an aerosol in the core, which is then subsequently enveloped.
• EP 1 236 459 describes light-curing dental composites with excellent handling properties and fracture toughness, which contain a filler which contains a mixture of size-adapted particles of irregular shape (0.1 to 1.0 ⁇ m), spherical particles (0.1 to 5, 0 ⁇ m) and very small particles (less than 0.1 ⁇ m). SiO 2 -ZrO 2 or SiO 2 -TiO 2 are mentioned as substances for the filler particles.
• Nanoparticulate metal oxide or mixed oxide fillers are of particular interest for use in dental materials, e.g. as filling composites, because on the one hand they enable the combination of different properties, e.g. high flexural strength, low abrasiveness and optimal X-ray opacity, and on the other hand due to their small particle size (less than 100 nm) enable the production of transparent or translucent materials, ie materials with tooth-like aesthetic properties (cf. "Nanotechnology for Dental Composites" N. Moszner, S. Klapdohr, Intern. J.
• Nanotechn., 1 (2004) 130- Such nanoparticulate metal oxide fillers can be produced, for example, by wet chemical means by hydrolytic condensation (sol-gel process) of individual metal alkoxides or their mixtures or by flame pyrolysis of suitable precursor compounds such as metal alkoxides, salts or halides are the physical and chemical properties of the nanoparticles depend, among other things, on their chemical composition and morphology, their particle size or size distribution and the surface modification.
• nanoparticle oxides in which at least one oxide is a nanoparticulate and X-ray-opaque metal oxide component, as a dental filler
• a dental filler is known from the following prior art: Nanoscale, pyrogenically produced yttrium-zirconium mixed oxide with a specific surface area of 1 to 800 m 2 / g is described in DE 101 38 573 as a ceramic base material for dental materials.
• DE 100 18405 describes spherical oxidic particles with a particle size of 5 to 10,000 nm which contain 0.1 to 99.9% by weight of an oxide of the elements titanium, aluminum, zirconium, yttrium or silicon and at least one other oxide Contain lanthanoids, whereby the particles can show a core-shell structure or a homogeneous distribution of the metal oxides.
• Dental materials based on nanoparticle fillers are described in WO 01/30304, WO 01/30305, WO 01/30306, WO 01/30307 in which, in addition to SiO particles, nanoparticulate heavy metal oxides of metals with an atomic number greater than 28 are additionally contained as X-ray-opaque filler.
• Examples of particularly preferred oxides are given as La, Zn, Sn, Y, Yb, Ba and Sr oxide or combinations thereof, the preferred particle size being less than 60 nm.
• Mixed oxides of SiO 2 and Yb 2 ⁇ 3 are not mentioned.
• the heavy metal oxide components described can form part of the coating of the SiO 2 particles.
• amorphous, nanoparticulate clusters are also claimed, which are preferably accessible from the non-heavy metal oxides, for example SiO 2 or AS2O3, and the oxides of the heavy metals, for example La, Zn, Sn, Y, Yb, Ba or Sr.
• cluster describes the way in which the particles are combined, the heavy metal oxides being present in the clusters as individual particles, as a coating of the non-heavy metal oxide particles or as a region in the non-heavy metal oxide particles.
• the heavy metal oxide in the non-heavy metal oxide particles can be present as a solid solution (for example as a continuous glass) and as a precipitate in a second phase.
• SiO 2 and ZrO 2 are listed as metal oxides, the clusters being produced such that, for example, commercially available SiO 2 particles have been chemically modified with zirconium acetate in a sol-gel manner.
• Ta 2 ⁇ 5-Si ⁇ 2 particles with a diameter between 50 to 100 nm are claimed in US Pat. No. 6,417,244 B1.
• the particle synthesis is carried out on the basis of dispersions of monodisperse SiO 2 particles (10 to 20 nm) and Ta2Os particles (1 to 2 nm).
• low-viscosity dental materials which contain non-agglomerated nanoparticles from 1 to 100 nm, where the filler specified includes pyrogenic silica, tantalum and niobium oxide and mixtures thereof.
• cationically polymerizable compositions are described in which, as X-ray-opaque fillers, oxides, their mixtures or mixed oxides of the elements La, Zn, Ta, Sn, Zr, Y, Yb, Ba, Sr with oxides of the elements AI, B or Si, which are accessible via the sol-gel process or via a melt.
• a particle size is not specified for the fillers.
• nanoparticulate fillers described in the prior art cited above bear on account of their 2-phase morphology (for example core-shell, doping, mixture of the oxides) and the associated non-homogeneous element distribution in the filler and the partially crystalline structure only insufficiently contribute to transparent properties in the composite.
• the refractive index of the fillers can only be adapted to that of the matrix to a limited extent.
• the nanoparticulate, non-spherical fillers usually show an extreme, but hardly influenceable thickening effect.
• the invention is based on the object of providing dental composites which, in comparison with the prior art, are distinguished by good X-ray opacity, high transparency and low intrinsic coloration by the filler, permit variation of the X-ray opacity, the refractive index and the thickening effect of the filler and for the production of Cements, veneering materials and especially filling composites are suitable for dental purposes.
• the object is achieved according to the invention by dental composites containing at least one nanoparticulate mixed oxide (a) of SiÜ2 with X-ray-opaque metal oxides of one or more elements selected from the group consisting of Y, La, Ta, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy , Ho, Er, Tm, Yb, Lu, whereby the mixed oxides are produced by spray flame synthesis, and which have an amorphous structure, a homogeneous element distribution, a very low organic content, a variable X-ray opacity or refractive index as well as a spherical particle shape and a reduced shape due to agglomeration Show thickening effect.
• a nanoparticulate mixed oxide
• X-ray-opaque metal oxides of one or more elements selected from the group consisting of Y, La, Ta, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy , Ho, Er, Tm,
• the mixed oxides according to the invention have a very homogeneous element distribution, which was not achievable with previous wet chemical processes.
• the production of the mixed oxides according to the invention is moreover economically more economical and easier to carry out because it is a continuous process.
• the refractive index of the primary particles can be adjusted with extremely small particle size (less than 50 nm) and narrow particle size distribution through the choice of components in the spray flame synthesis.
• the grain sizes of the mixed oxides according to the invention can be specifically adjusted by the production process.
• the reactor In spray flame pyrolysis, the reactor consists of a multi-component nozzle which is concentrically surrounded by an auxiliary flame (L. Madler, HK Kammler, R. Mueller, and SE Pratsinis, "Controlled synthesis of nanostructured particles by flame spray pyrolysis, "Journal of Aerosol Science, vol. 33, pp. 369-389, 2002; L. Madler, WJ Stark, and SE Pratsinis," Flame-made ceria nanoparticles, "Journal of Materials Research, vol. 17, pp. 1356-1362, 2002; R. Mueller, L.
• the auxiliary flame serves to ignite the spray and is fed with a flammable gas mixture (eg CH / O 2 , H2 / O2)
• a flammable gas mixture eg CH / O 2 , H2 / O2
• the multi-component nozzle disperses at least one flammable liquid in finely divided droplets, which ideally are between 1 ⁇ m and 100 ⁇ m in size
• the particles formed in the spray flame are cooled down by mixing with ambient air.
• other cooling methods are also possible, for example injecting liquids with high evaporation enthalpy or nozzle quenching (K.
• the gas-borne particles are then separated on a suitable filter and cleaned from it.
• the dispersed liquid contains both the fuel and the metal oxide precursors. Tetraalkoxysilanes, such as trimethylsilane or tetraethylsilane, are preferred as precursors for S1O2.
• suitable metal salts such as nitrates, halides
• suitable or carboxylates such as formates, acetates, oxalates, triflates, 2-ethylhexanoates and naphthenates, metal alkoxides and metal chelates such as chelates of acetylacetone, acetoacetic ester, dimethylglyoxime, salicylaldehyde, 8-hydroxyquinoline or o-phenanthroline, which are dissolved in a suitable solvent or can be converted into a readily homogeneously soluble metal compound by appropriate reactions.
• the precursor liquid should preferably be a homogeneous solution, although in principle emulsions are also possible. If a multi-component nozzle with several liquid feeds is used, the fuel and the respective metal oxide precursors can also be atomized separately.
• the fuel consists of an organic solvent in which the metal oxide precursor (s) are present in solution.
• Preferred solvents / fuels are, above all, alcohols, organic acids and aromatic and / or aliphatic hydrocarbons. Particle formation can be imagined in such a way that the multi-component nozzle atomizes the precursor solvent / fuel / liquid mixture into fine droplets. In the flame, these droplets are exposed to very high temperatures (1500-2500 K).
• the fuel / solvent the amount and type of atomizing gas and the amount of liquid supply, chemical composition, the morphology, the particle size or size distribution and product properties of the SiO ⁇ formed - Control mixed oxide particles in a targeted manner.
• the particle size and thus its specific surface area can be varied by the amount and the energy content of the precursor solvent / fuel / liquid mixture and the type and amount of dispersion gas (cf. L. Madler, WJ Stark, and SE Pratsinis, "Flame-made ceria nanoparticles, "Journal of Materials Research, vol. 17, pp. 1356-1362, 2002; L Madler, HK Kammler, R.
• the mixed oxides (a) according to the invention preferably have an average primary particle size of 3 to 100 nm, in particular 5 to 40 nm, determined by measuring the BET surface area.
• the nanoparticulate mixed oxides of SiO 2 produced by spray flame synthesis with X-ray-opaque metal oxides of one or more elements selected from the group consisting of Y, La, Ta, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb , Lu can be used as radiopaque fillers.
• the mixed oxides can be used as X-ray opaque fillers in virtually any work piece where the presence of an X-ray opaque filler, e.g. for analysis, is advantageous to be used. They are preferably used in dental composites.
• the x-ray-opaque mixed oxide nanofillers produced by spray flame synthesis are dispersed in suitable polymerizable matrix resins, then mixed with the photoinitiator system and, if appropriate, further additives and cured by thermal or light-induced polymerization.
• the degree of filling of a nano-filled composite can be increased even further by incorporating the nano-filler into a prepolymerized filler.
• Commercially available diluent monomers such as mono (meth) acrylates, e.g.
• crosslinking monomers such as e.g. Bisphenol-A-di (meth) acrylate, bis-GMA, UDMA, di-, tri- or tetraethylene glycol di (meth) acrylate, 1,10-decanediol di (meth) acrylate, trimethylolpropane tri (meth) acrylate,
• Pentaerythritol tetra (meth) acrylate, butanediol di (meth) acrylate or 1,12-dodecanediol di (meth) acrylate can be used.
• Free-radically polymerizable oligomers or polymers which carry terminal and / or pendant free-radically polymerizable groups are, for example, free-radically polymerizable ⁇ , ⁇ - (meth) acryloyl-terminated polyester, polyether, polyepoxide, amine or polyurethane telechelics or silica polycondensates, which use, for example, by hydrolytic condensation of silanes which carry free-radically polymerizable groups, preferably for example methacrylic or acrylic groups.
• Such silicic acid polycondensates are also described in DE 44 16 857 C1 or DE 41 33 494 C2. ⁇
• Suitable matrix monomers for cationic photopolymerizates are, in particular, cationically polymerizable diluent or crosslinking monomer such as, for example, glycidyl ether or cycloaliphatic epoxies, cyclic ketene acetals, vinyl ethers, spiro-orthocarbonates, oxetanes or bicyclic orthoesters.
• Examples include: triethylene glycol divinyl ether, cyclohexanedimethanol divinyl ether, 2-methylene-1, 4,6-trioxaspiro [2.2] nonane, 3,9-dimethylene-1, 5,7,11-tetraoxaspiro [5.5] undecane, 2-methylene-1, 3-dioxepane, 2-phenyl-4-methylene-1,3-dioxolane, bisphenol-A diglycidyl ether, 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexane carboxylate, bis (- (3,4-epoxycyclohexylmethyl) adipate, vinylcyclohexene dioxide, 3-ethyl (3-hydroxymethyl oxetane, 1, 10, -decanediylbis (oxymethylene) bis (3-ethyloxetane) or 3,3- (4-xylylenedioxy) bis (methyl-3-eth
• silicic acid polycondensates which, for example by hydrolytic condensation of silanes, carry the cationically polymerizable groups, preferably, for example, epoxy, oxetane, spiro orthoesters or vinyl ether groups.
• silicic acid polycondensates are described, for example, in DE 41 33494 C2 or US 6,096,903.
• polymerization initiators preferably thermal and / or photoinitiators, are added to the compositions used according to the invention.
• thermal initiators are the known peroxides, such as, for example, dibenzoyl peroxide, dilauryl peroxide, tert-butyl peroctoate or tert-butyl perbenzoate, and azobisisobutyroethyl ester or azoisobutyronitrile (AIBN), benzpinacol or 2,2-dimethylbenzpinacol.
• suitable photoinitiators are benzophenone, benzoin and their derivatives or ⁇ -diketones or their derivatives such as 9,10-phenanthrenequinone, 1-phenyl-1,2-propanedione, diacetyl- or 4,4-dichlorobenzil.
• Camphorquinone and 2,2-methoxy-2-phenyl-acetophenone are particularly preferred, and ⁇ -diketones in combination with amines as reducing agents, such as, for example, N-cyanoethyl-N-methylaniline, 4- (N, N-dimethylamino) benzoate, are particularly preferred , N, N-dimethylaminoethyl methacrylate, N, N-dimethyl-sym.-xylidine or triethanolamine used.
• acylphosphines such as 2,4,6-trimethylbenzoyldiphenyl or bis (2,6-dichlorobenzoyl) -4-N-propylphenylphosphine oxide are also particularly suitable.
• Diaryliodonium or triarylsulfonium salts such as, for example, are particularly suitable for the dual curing of free-radically and cationically polymerizable systems
• Triphenylsulfonium hexafluorophosphate or hexafluoroantimonate Triphenylsulfonium hexafluorophosphate or hexafluoroantimonate.
• Redox initiator combinations such as combinations of benzoyl or lauryl peroxide with N, N-dimethyl-sym.-xylidine or N, N-dimethyl-p-toluidine, are used as initiators for a polymerization carried out at room temperature.
• these are usually surface-treated with silanes, the silanes containing suitable polymerizable groups, such as (meth) acrylic, vinyl, oxetane or epoxy groups.
• compositions used according to the invention can be filled with further organic or inorganic particles or fibers to improve the mechanical properties.
• Preferred inorganic particulate fillers are nanoparticulate or microfine fillers, such as pyrogenic silica or precipitated silica, and macro or mini-fillers, such as quartz, glass ceramic or glass powder with an average particle size of 0.01 to 5 ⁇ m as well as radiopaque fillers such as ytterbium trifluoride. Titanium, glass fibers, polyamide or carbon fibers can also be used.
• the compositions used according to the invention can contain further additives, such as, for example, stabilizers, flavorings, microbiocidal active ingredients, optical brighteners, plasticizers or UV absorbers.
• a preferred composition used according to the invention contains:
• nanoparticulate mixed oxide (a) 5 to 90, in particular 10 to 70% by weight of at least one nanoparticulate mixed oxide (a) of SiO 2 with X-ray-opaque metal oxides of one or more elements selected from the group consisting of Y, La, Ta, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, the mixed oxides being produced by spray flame synthesis, and
• a particularly preferred composition used according to the invention contains:
• nanoparticulate mixed oxide (a) 5 to 90, in particular 10 to 70% by weight of at least one nanoparticulate mixed oxide (a) of SiO ⁇ with X-ray-opaque metal oxides of one or more elements selected from the group consisting of Y, La, Ta, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, the mixed oxides being produced by spray flame synthesis, and
• the dental composites of the present invention are free of apatites.
• the dental composites according to the invention can e.g. can be used by filling them directly into dental cavities or by applying them to the surfaces of teeth.
• an impression of a tooth cavity can be made for the production of inlays or onlays, on the basis of which a suitable inlays or onlays are then made.
• the composites according to the invention can also be used for filling or
• Coating of any substrates, but especially of teeth can be used.
• the composites are normally used in such a way that they are applied successively (I) or filled into a mold,
• FIG. 1 shows (scale in nm) images of different magnifications (left 10 thousand times, right 50 thousand times) by means of transmission electron microscopy (TEM) of a Yb ⁇ 3 / SiO 2 mixed oxide powder (30% by mass Yb 2 O 3 ) by spray flame synthesis.
• the overview images show the morphological homogeneity of the product, which consists of partially aggregated primary particles.
• the primary particles of the powder are characterized by their spherical shape.
• FIG. 2 shows an electron micrograph of a Yb / Si mixed oxide (50% by mass Yb 2 ⁇ 3) from the spray flame synthesis (top picture). With this Yb 2 ⁇ 3 mass fraction too, the primary particles are spherical.
• the lower pictures show the electron spectroscopy picture (ESI) for the energy absorption edges of Yb-M (1.53 and 1.58 keV) (middle) and Si-K (1, 84 keV) (bottom picture).
• ESI electron spectroscopy picture
• FIG. 3 shows DRIFTS spectra (diffuse reflection infrared spectroscopy) of Yb / Si mixed oxides with different Yb 2 ⁇ 3 content (0 to 50% by mass) produced by means of the spray flame synthesis.
• a broad absorption signal between 1000 and 900 cm -1 is shown , the intensity of which increases with increasing ytterbium content.
• This broad absorption band corresponds to degenerate vibration modes caused by the presence of ytterbium.
• the increased intensity of the absorption with increasing ytterbium content confirms the atomic distribution of the ytterbium in the powder.
• FIG. 4 shows XRD (X-ray diffractograms) of Yb / Si mixed oxides with different Yb2 ⁇ 3 content (0 to 50% by mass) produced by means of spray flame synthesis.
• the diffraction pattern of pure cubic YD2O3 is shown by vertical lines. None of the powders show pronounced X-ray diffraction patterns; accordingly, all samples are X-ray amorphous. Neither Yb 2 ⁇ 3 crystals nor ytterbium silicates could be detected. Examples
• test specimens with a dimension of 25mm * 2mm * 2mm are produced with the composite paste and with a dental radiation source Spectramat (Ivoclar Vivadent) each for 3 minutes, i.e. Cured 2 * 3 minutes. After the test specimens had been stored in water at 37 ° C. for 24 hours, the mechanical properties were determined using a Zwick universal testing machine from Zwick. Transparency:
• a white light beam is sent for calibration through a cuvette filled with water (layer thickness: 2mm), which corresponds to a transparency of 100%. Then the cuvette is replaced by a composite test specimen (layer thickness: 1mm) and the transmitted light is measured in comparison to the water cuvette, which then corresponds to the transparency of the composite.
• X-ray opacity Using a dental X-ray camera, an X-ray is taken of a composite test specimen with a layer thickness of 2 mm and a standardized AI staircase, each with a step height of 0.5 mm, and the blackening of the composite sample and AI staircase are compared. The blackening of 2mm AI corresponds to an X-ray opacity of 100% AI.
• Example 1 Synthesis of the mixed oxides of the elements Si and Yb
• a two-fluid nozzle was used, the liquid supply being 5 ml / min.
• the atomizing gas was oxygen (5 l / min).
• the support flame was operated with premixed methane / oxygen (1.5 l / min / 3.2 l / min).
• the envelope air flow was 5 l / min oxygen.
• Tetraethoxysilane (TEOS) and ytterbium nitrate pentahydrate (Yb (NO) 3 * 5H 2 O) were used as precursors for Si and Yb.
• Table 2 shows an example of the specific surface area of the powder, using the flame characteristic, here changing the amount of atomizing air (reduction from 5 l / min to 3 l / min) and liquid supply (increase from 5 ml / min to 8 ml / min) can be changed or adjusted significantly.
• the refractive index of the powder was almost unaffected.
• Table 2 Change in the specific surface of the Yb / Si mixed oxide powder by varying the spray flame parameters
• Example 2 Evaluation of the thickening effect of the mixed oxides of the elements Si and Yb produced according to Example 1
• model composite pastes were produced from 16.5% Yb / Si mixed oxide of various specific surface areas and 83.5% free-radically polymerizable monomer composition (41.82 parts Bis-GMA, 37 parts UDMA, 20 parts TEGDMA, 0.73 parts photoinitiator , 0.55 parts of additives). Between two glass plates, 0.1 g of paste was loaded with a load of 120 g over a period of three minutes and the resulting diameter of the paste was determined. The thinner this so-called slice consistency of the paste, i.e. the lower the thickening effect, the larger the resulting diameter. The results show that the consistency of the pastes clearly depends on the specific surface of the nanoparticle filler (Table 3).
• the thickening effect can be reduced by agglomerate formation.
• the agglomeration takes place, for example, in such a way that 37.5% deionized water are initially introduced and 62.4% mixed oxide and 0.16% potassium fluorozirconate are slowly stirred in until a homogeneous suspension is achieved. This suspension is dried at 120 ° C. for 30 hours, ground in a ball mill and sieved. After that the agglomerated filler can be used for the production of a composite.
• Example 3 Production of a filling composite based on a mixed oxide of the elements Si and Yb produced according to Example 1
• Composite A based on 48 mass% of light-curing monomer composition (41.82 parts Bis-GMA, 37 parts UDMA, 20 parts TEGDMA, 0.73 parts photoinitiator, 0.55 parts) and 52 mass % of an X-ray-opaque Yb / Si mixed oxide produced by spray flame synthesis according to Example 1 with a Yb 2 ⁇ 3 content of 30% by mass and a specific surface area of 125 m 2 / g.
• a composite (composite B) based on 50% by mass of the same light-curing monomer, 35% by mass of silanized pyrogenic SiO 2 OX-50 and 15% by mass of ytterbium fluoride was produced and, after the composites had hardened, the transparency and X-ray opacity determined:
• Example 4 Production of a filling composite based on a prepolymerized filler starting from a mixed oxide produced according to Example 1.
• a prepolymerized filler prepolymer
• a homogeneous mixture was prepared, which was then polymerized for 1 hour at 120 ° C.
• Test specimens were prepared from this, which were cured 2x3 minutes in the Spectramat (Ivoclar Vivadent) light oven and stored in water for 24 hours at 37 ° C. The following properties were determined: Flexural strength 110 MPa Flexural modulus 6500 MPa Transparency 14% X-ray opacity 300% AI
• Example 5 Production of a filling composite based on a Yb / Si mixed oxide and a conventional glass filler.
• a composite based on 20% by mass of light-curing monomer composition (41.82 parts Bis-GMA, 37 parts UDMA, 20 parts TEGDMA, 0.73 parts photoinitiator, 0.55 parts additives), 40% by mass of an X-ray-opaque Yb / Si mixed oxide prepared according to Example 1 by spray flame synthesis (30% by mass Yb 2 ⁇ 3 and specific surface area of 125 m 2 / g) , and 40% by mass of a silanized Ba-Al silicate glass (GM 27884 from Schott) with an average particle size of 1.0 ⁇ m.
• GM 27884 silanized Ba-Al silicate glass
• Test specimens were prepared from this, which were cured 2x3 minutes in the Spectramat light oven (Ivoclar Vivadent) and stored in water for 24 hours at 37 ° C. The following properties were determined: Flexural strength 130 MPa Flexural modulus 9000 MPa Transparency 14% X-ray opacity 400% Al

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