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    • 专利摘要:
    The invention relates to a dispersion (10) of a nanoparticulate mixed oxide (6) of SiO 2 with at least one further metal oxide in a matrix monomer (8), a dental composite which can be prepared by curing the dispersion (10), and the use of the dispersion according to the invention ( 10) as precursor for dental composites. Furthermore, the invention relates to a method for producing a corresponding dispersion (10).
    公开号:CH707494B1
    申请号:CH00033/14
    申请日:2014-01-14
    公开日:2017-09-29
    发明作者:Jörg Schuhmacher Dr；Hermann Jochen；Schmitt Hans-Joachim；Schön Bastian；Suffner Jens
    申请人:Schott Ag；
    IPC主号:
    专利说明:

    Description Field of the Invention The invention relates to a dispersion of a nanoparticulate mixed oxide of SiO 2 with at least one further metal oxide in a matrix monomer, a dental composite with the dispersion as precursor, obtainable by curing the dispersion, and the use of the dispersion according to the invention as precursor for dental composites , Furthermore, the invention relates to a process for the preparation of a corresponding dispersion.
    PRIOR ART Dental composites are composite materials which consist of a polymeric, organic phase, in particular a resin matrix, and also fillers, preference being given to using inorganic particles as the filler. The precursor for such a dental composite is a dispersion of fillers in a monomer. The precursor is in a liquid or pasty form, i. the filler particles are incorporated here into a liquid organic phase. In this case, the liquid organic phase contains monomers which can be converted by polymerization into the resin matrix. By curing the dispersion, i. Polymerization of the monomers, the corresponding dental composite is formed. The physical properties of the dental composite are mainly determined by the type and proportion of inorganic fillers, their shape and size and size distribution. By using a suitable filler, adverse effects such as polymerisation shrinkage of the matrix or its water absorption can be compensated or reduced.
    Furthermore, a suitable filler can reduce the thermal expansion coefficient of the composite. At the same time, the compressive, tensile, bending and abrasion resistance as well as the modulus of elasticity of the composite can be adjusted. These effects correspond with the filler content in the composite.
    When using the dispersion as a precursor for dental composites, for example as a dental filling, the polymerization of the monomers is usually induced by light in the visible or UV range. For the mechanical properties, in particular for the durability of the fillings, the highest possible degree of polymerization over the entire volume of the filling is desired. In particular, for the polymerization of deep fillings, i. For fillers with a relatively large layer thickness, it is therefore advantageous if the composite material has high transmission values in the visible range. Scattering losses, as caused for example by scattering on larger filler particles or different refractive indices of filler and matrix, have an adverse effect on the translucency.
    At the same time, the composite material for X-radiation should be as opaque as possible, i. The material should have a high radiopacity to allow X-ray diagnosis.
    The first commercially available dental composites contained ground glass powders as fillers. The mean grain size was between 50 and 100 pm. The size of these macrofillers, however, caused a high abrasion. By breaking the glass splinters out of the filling, craters were again formed in the filling surface, and the broken glass fragments also acted as emery, thus intensifying the abrasion of the filling.
    By combining pyrogenic silica as a nanofiller and ground glass particles as a microfiller so-called. Hybrid filler can be obtained, which allow a higher solids content in the composite. Thus, composites can be obtained which have good polishability, high abrasion strengths and good mechanical strengths.
    By conventional melting and milling glass powder can be obtained with particle sizes less than 1 pm. A disadvantage of this production method, however, is that the composition of the glass in addition to constituents, which ensure the functional properties, in particular the refractive index and the X-ray opacity of the packing, also contains components which ensure the meltability in a technically relevant area and suppress crystallization. As a result, however, as a rule, the refractive index of the material is raised and thus, for example, the choice of the components relevant for the radiopacity, which in turn likewise bring about an increase in the refractive index of the material, is limited in type and content. Furthermore, the production of glass powders or glass particles in nanoscale form, i. with a particle diameter smaller than 100 nm due to the necessary grinding time usually not economical. In addition, there is always the danger that the materials leach out during the grinding process and thus lose their desired properties, especially with long grinding times.
    The patent EP 1 711 433 B1, in contrast, describes dental composites which comprise a mixed oxide of SiO 2 obtainable by spray flame pyrolysis and at least one further oxide of an element of the group Y, La, Ta, Ce, Pr, Nd, Sm, Eu, Gd, Tb , Dy, Ho, Er, Tm, Yb or Lu as X-ray opaque component. However, the corresponding dental composites show only a relatively low radiopacity and a poor transparency for light in the visible range.
    The published patent application DE 10 2006 045 628 A1 likewise discloses composite materials having at least one nanoparticulate mixed oxide comprising SiO 2 and an oxide of the elements Y, La, Ta, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho , He, Tm, Yb and Lu. Due to the great difference between the refractive indices of fillers and matrix, however, a low transparency of the composite is also to be assumed here.
    Instead of the above-mentioned provision methods for packing, the production of inorganic packing can also be done by means of chemical precipitation.
    Thus, in the patent DE 19 643 781 C2 describes the representation of radiopaque, spherical particles via a sol-gel route. The particles thus obtained contain SnO 2 and at least one further oxide of the elements of the 1st to 5th main group and / or the transition metals. However, the particles necessarily contain SnO 2.
    The literature (Wei et al., Journal of Applied Polymer Science, 70, 1689-1699 [1998]) further describes the preparation of a filler based on SiO 2 by means of a sol-gel process. It is a filler in which polymer chains are covalently bound to the silicon network. The filler thus obtained exhibits increased compressive strength as a composite with the corresponding matrix monomer, but no components for increasing the radiopacity are contained in the composite.
    It is therefore an object of the present invention to provide dispersions of filler particles in a monomer as precursors for translucent dental composites based on nanoscale radiopaque fillers and the corresponding dental composites. In particular, the composites according to the invention should also have advantageous physical-mechanical properties compared with the prior art.
    Another object of the invention is to provide a suitable process for the preparation of the novel dispersions or composite precursors.
    The object of the invention is already achieved by the subject matter of the independent claims. Advantageous embodiments and further developments of the invention are the subject of the respective subclaims.
    DESCRIPTION OF THE INVENTION The novel dispersions comprise a filler and at least one monomer. Hereinafter these dispersions are also referred to as composite precursors. The monomer has at least one polymerizable group. The polymerization of the monomer forms a matrix. Depending on the monomer used, the polymerization may be, for example, a free-radical or cationic polymerization of vinylic double bonds. The curing of the composite can also be carried out by a cationic, ring-opening polymerization.
    In particular, the monomer can be polymerized by the irradiation of light. For this purpose, an initiator may additionally be added to the dental composite.
    The filler contained in the dental composite shows a nanoscale structure. The particles of the filler preferably have a spherical or at least largely spherical structure, which leads to a very good polishability in the application case. Thus, there is a much lower risk of spherical particles breaking out of the composite surface during the polishing process than is the case, for example, with particles with sharp edges, such as those obtained by grinding glass. However, fracturing of the filler particles from the polymer matrix results in the formation of craters, which in turn are preferred plaque attachment sites. Therefore, the inventive composites are superior to corresponding composites with sharp-edged particles in terms of abrasion resistance and polishability.
    The filler is a mixed oxide, which contains at least one metal M in oxidic form in addition to silicon. The metal M has an atomic number greater than 36 and is radiopaque. By using a corresponding mixed oxide, it is thus possible to obtain a radiopaque filler.
    It is particularly advantageous that on the selection of the corresponding metal M and its quantitative proportion in the mixed oxide in addition to the desired radiopacity simultaneously the refractive index of the filler particles can be adjusted. The refractive index is brought to the desired value only by the addition of the X-ray opacifier. Unlike dental glasses, which are produced via conventional melting and grinding routes, the fillers according to the invention contain no additional oxide components which have to be added for manufacturing reasons (for example increasing the meltability) and indeed increase the refractive index but do not contribute to the X-ray opacity. The fillers according to the invention can thus have a high x-ray opacity without leaving the advantageous range of the refractive index predetermined by the matrix.
    Preferably, the refractive index of the fillers is adjusted so that it largely coincides with the refractive index of the matrix monomer. If matrix monomer and filler have similar or largely identical refractive indices, this has a positive effect on the transparency of the composite. A high transparency of the composite has an advantageous effect on the homogeneity of the polymerization within the filling and on the degree of polymerization. Furthermore, high transparency is advantageous for the aesthetic appearance of the composite. Preferably, the difference between the refractive index of the filler and the refractive index of the matrix monomer is less than 0.1, more preferably less than 0.05, and most preferably less than 0.02. According to one embodiment, the polymer matrix has a refractive index in the range from 1.51 to 1.7, preferably in the range from 1.53 to 1.55.
    The particles of the inventive filler, also referred to below as mixed oxide particles, also have a surface functionalization. Thus, at least one polymerizable group is covalently bonded to the surface of the filler particle or the mixed oxide particle. The polymerizable group is polymerizable under the same conditions as the matrix monomers and forms a copolymer with these. As a result of the copolymerization of matrix monomer and filler, a permanent chemical bond thus exists between matrix and filler. In addition, the surface functionalization of the fillers leads to a good dispersibility of the fillers in the matrix monomer and thus to a uniform distribution of the filler particles in the dispersion. This uniform distribution and covalent bonding of cured matrix and filler increases the mechanical strength of the composite. The solids content of the dispersion is preferably from 10 to 70% by weight, particularly preferably from 20 to 60% by weight and very particularly preferably from 30 to 50% by weight.
    According to an advantageous embodiment of the invention, the mixed oxide of the filler is a binary mixed oxide according to the formula SiO 2 -MO x, wherein the metal M is radiopaque. X-ray opacity and refractive index of the mixed oxide can be adjusted via the nature and proportion of the metal M in the mixed oxide. A development of the invention provides as filler a ternary mixed oxide according to the formula SiO 2 -MO x MOy with the metals M and M 'before. Both metals M and M 'are X-ray opaque metals with an atomic number greater than 36, i. Opaque, wherein the two opaquers can be present in different proportions in the filler. By using two different opaquers, which also differed in terms of their contribution to the refractive index, additional parameters for adjusting the refractive index and radiopacity are available.
    The metals M and M 'are preferably selected from the group of the elements Ba, Sr, La, Cs, Sn, Zr, Yb, Y, Ta, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Lu, Bi are preferably from the group of elements Ba, Sr. More preferably, the metals M and M 'are barium and / or strontium.
    Particularly advantageous is the introduction of the polymerizable group has been found by a correspondingly functionalized silane.
    Preferably, the mixed oxide particles have a degree of modification with co-polymerizable groups of 0.001 to 1.5, particularly preferably from 0.01 to 0.7. For the purposes of the invention, the degree of modification M-1 with co-polymerisable groups means the molar ratio of co-polymerizable group to inorganic part of the mixed oxide particle (corresponding to the quantities of silicon and metal M or metals M and M '), in particular the ratio of the amounts of substances n M, = n (co-polymerizable groups) / n (Si) + n (M) or M-, = n (co-polymerizable groups) / n (Si) + n (M) + n (M ') understood.
    In one embodiment, the dispersion contains further components. These may be, for example, initiators, colorants or stabilizers.
    Preference is given to acrylates, in particular methacrylates such as, for example, methyl, ethyl, butyl, benzyl, fur-furyl or phenyl (meth) acrylate and also 2-hydroxyethyl or -propyl (meth) acrylate or mixtures of different acrylates. In addition to monofunctional monomers it is also possible to use polyfunctional monomers such as, but not limited to, bisphenol A di (meth) acrylate, bis-GMA, ethoxylated bisphenol A di (meth) acrylate, UDMA, di-, tri- or tetraethylene glycol di ( meth) acrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol tetra (meth) acrylate and butanediol di (meth) acrylate, 1,10-decanediol di (meth) acrylate or 1,12-Dodecandioldi (meth) acrylate. Particularly advantageous is the use of bis-GMA has been found. Thus, composites with a matrix based on bis-GMA show a significantly lower polymerization shrinkage than, for example, composites with MMA as matrix monomer. It is also possible to use mixtures of different methacrylates. Thus, the combination of bis-GMA with a low-viscosity methacrylate as co-monomer, the overall viscosity of the matrix monomers can be lowered, which in particular has a favorable effect on the rate of polymerization. For example, bis-GMA can be used in combination with TEG-DMA.
    According to another embodiment, monomer and filler particles as the polymerizable group on epoxides.
    By the copolymerization of the functionalized filler and the matrix monomers matrix and filler are covalently bonded. Thus, an embodiment of the invention provides that the filler is functionalized with a silane having a side chain on acrylate, in particular methacrylate-based, such as 3 Methacryloxypropyltrime-thoxysilane (MPTMS) carries.
    A further development of the invention additionally provides for functionalization of the mixed oxide particles with organic radicals which have none with copolymerizable groups. In one embodiment of the invention, the particles have organic aliphatic radicals or side chains. In particular alkyltrialkoxysilanes such as e.g. Alkyltrimethoxysilanes, alkyltriethoxysilanes and corresponding mixtures can be used. The corresponding
    Alkyltrialkoxysilanes as a second silanization agent are preferably used in combination with a copolymerizable silane.
    The non-copolymerizable organic radicals or side chains cause a flexibilization of the overall system and thus counteract embrittlement and cracking of the cured composite. In addition, the viscosity of the dispersion can be lowered and its pot life significantly increased.
    The degree of modification M2 of the particles having non-copolymerisable organic side chains is preferably 0.001 to 1.0, particularly preferably 0.01 to 0.5 and can be defined as molar ratio with n = amount of substance in mol as follows: M2 = n (not polymerizable groups) / n (Si) + n (M) or M2 = n (non-polymerizable groups) / n (Si) + n (M) + n (M ') In one embodiment of the invention, the filler particles an average particle size of 5 to 100 nm, preferably from 10 to 70 nm and particularly preferably from 20 to 50 nm. The small particle size of the filler leads to a high mechanical stability of the composite or the filling formed therefrom. Furthermore, it is ensured by the small particle size that it does not lead to an undesirable light scattering on the filler and thus not to turbidity effects in the composite.
    A further development of the invention provides that the refractive index of the filler, via its composition, be adapted to the refractive index of the matrix monomer used so far that the difference between the refractive index of the filler and the refractive index of the matrix monomer is less than 0.10, preferably less than 0, 05, so that stray losses are minimized. In particular, the composite for light in the visible range has a translucency of at least 30%, preferably at least 50%, particularly preferably at least 70%. In particular, the composite for light in the visible range has a transparency of at least 75%, in particular at least 85% or even at least 90%, with a solids content of at least 10% by weight.
    An X-ray opacity of the nanoscale fillers of the dispersion or of the composite obtained from 50 to 1500% Al, in particular even in the range of 75 to 1000% Al and preferably in the range of 100 to 800% Al is particularly advantageous.
    Furthermore, the invention relates to a preparation process for providing a dispersion in particular as a precursor for a dental composite comprising a nanoscale mixed oxide as a filler and a matrix monomer by sol formation. In particular, a process for producing the above-described dispersions of the invention is provided.
    The production process according to the invention comprises the following process steps: a) Particle production as colloidal solution by formation of a sol b) Functionalization of the particles c) Purification of the reaction solution of undesired components d) Redispersion of the functionalized particles in the matrix monomer e) Preparation of the particle-matrix monomer dispersion In step a), the nanoscale mixed oxide particles are prepared by sol formation according to a sol-gel method, wherein the particles are present as a sol. For this purpose, an organic silicon precursor, for example in Te-traalkoxysilan in the presence of a metal salt MaXb is brought to water with reaction, wherein a base is used as the catalyst.
    For this purpose, according to one embodiment, first a solution A containing a silicon precursor and a metal salt dissolved in a solvent and a solution B containing a solvent and an aqueous basic solution are provided. In addition, one of the two solutions contains a sol-stabilizer. To start the reaction, solution A is added to solution B under convection. Preferably, solution B contains ammonia as the base. The solvents used in solution A and B are preferably a low-boiling alcohol such as ethanol, methanol or isopropanol.
    By thus taking place hydrolysis of the precursors, a corresponding sol is formed.
    The metal M is an X-ray opaque metal, i. the metal M has an atomic number greater than 36. The metal precursor used reacts with the metal oxide MOx contained in the mixed oxide.
    When using a precursor MaXb, the mixed oxide particles have a composition SiO 2 -MO x with variable proportions of SiO 2 and MO x and are X-ray opaque.
    To form the metal oxides MOx are used as precursors in place of metal alkoxides, which are usually very sensitive to air and moisture, the corresponding metals as metal salts of the form MaXb or their hydroxides used.
    On the one hand, this simplifies the reaction procedure, since the particle formation does not have to take place under protective gas. Furthermore, the metal salts are usually less expensive and also show good solubility in the solvents used.
    An embodiment of the invention provides for the use of the corresponding metal perchlorates as precursor. In particular, barium and strontium perchlorate have a good solubility in the solvents used.
    In another embodiment, metal hydroxides are used as precursors. These are at least partially neutralized by the addition of acids, in particular by the addition of methacrylic acids. The partially neutralized solutions have a weakly alkaline pH. Depending on the acid used, the metal hydroxides can also be completely neutralized.
    Furthermore, in step a), a sol stabilizer is used to stabilize the sol.
    By introducing a further, in particular a basic oxide into the silicate material system, the zero crossing of the zeta potential shifts to pH values of 8 to 9, while the zero crossing for pure SiO 2 is at a pH of 2. However, since the particle synthesis takes place at pH values of 8 to 9, in the case of mixed oxide particle synthesis, the particles formed in the process are largely free of surface charge and tend to agglomerate strongly, since now no repulsive electrostatic interactions, but only the attractive van der Waals forces between the particles are effective. However, the use of a sol stabilizer avoids the formation of agglomerates and thus also the formation of a precipitate as a result of steric stabilization of the particles. Thus, in the course of the particle synthesis, a colloidal solution is obtained, which can be converted into a nanoparticle-filled matrix monomer dispersion with the subsequent steps.
    As sol stabilizers, bulky silanes, i. Silanes can be used with a sterically demanding organic radical or protective colloids. In one embodiment of the invention, hydroxypropylcellulose is used as the protective colloid. If silanes are used as sol stabilizers, particle formation and surface modification can take place in a single step.
    Furthermore, stabilization of the sol results in too rapid a reaction of the metal oxide precursor MOx precursor and thus segregation, i. Separate formation of SiO 2 and MOx particles avoided. Thus, the formation of a mixed oxide particle is made possible by the use of a suitable sol stabilizer.
    By the synthesis conditions selected in step a), the formation of the mixed oxide particles takes place in selbstorganisierenderweise. Preferably, in step a) ammonia or an ammoniacal solution is used as the base. Thus, the particles form a spherical geometry during the synthesis, so that it is possible to dispense with a separate rounding step in the course of the overall production process.
    Furthermore, occurs in the context of particle synthesis, only a sol formation, but not a gelation. Thus, no gelling step with subsequent drying and calcination is necessary to represent the desired mixed particles. Thus, the overall manufacturing process can be simplified.
    In the case of gelling and calcination processes, there is also the risk that the particles agglomerate, aggregate or sinter during the corresponding post-processing steps. The agglomerates or aggregates and sintering units formed must be broken up mechanically with considerable energy and time, whereby nanoclusters can be left behind, which can lead to an undesirable light scattering and thus to turbidity effects.
    In step b) there is a surface functionalization of the mixed oxides. In this case, the reaction solution provided in step a) is mixed with a functionalized silane after completion of the particle formation. The silane has polymerizable groups which can be copolymerized with the matrix monomer used. The introduction of the polymerizable group via a silane causes a surface modification with formation of covalent bonds. According to one embodiment, silanes of the formula ASiX3 or ARSiX2 are used, wherein X is hydrolyzable groups and group A is a copolymerizable functional group. Optionally, the silane may further comprise a non-hydrolyzable organic radical R. Preferably, the group X is selected from X = OR, halogen, NR "2 with R" = alkyl, aryl.
    When using a sterically demanding silane as a sol stabilizer carried particle formation and their surface modification in a common step.
    By copolymerizing the polymerizable groups of the mixed oxide with the matrix monomer thus a permanent chemical bond between filler and matrix monomer is achieved, which is particularly advantageous in view of the mechanical strength of the composite.
    Furthermore, the surface modification of the mixed oxide particles leads to an easier dispersibility of the filler particles in the matrix monomer [step dj).
    The coupling of the silanization agent to the surface of the mixed oxide takes place under the same reaction conditions as the particle formation in step a), so that no further work-up steps or changes in the reaction conditions must be carried out before the addition of the silane. Preferably, 3-methacryloxypropyltri-methoxysilane is used as the silanization agent.
    A further development of the invention additionally provides for the use of at least one further silane for surface modification with an organic, non-copolymerizable radical, in particular with an aliphatic radical. Preference is given to silanes of the formula.
    RSiX3 or RR'SiX2 used, where X is hydrolyzable groups and the groups R and R 'are non-hydrolyzable organic radicals. Preferably, the group X is selected from X = OR, halogen, NR "2 with R" = alkyl, aryl.
    Unlike the use of metal alkoxides falls in the inventive use of metal salts, the counterion or when using metal hydroxides, the corresponding base of the acid used in step a) as an undesirable component or by-product, which must be separated.
    Step c) of the production process according to the invention provides only separation of the counterion by ion exchange. Via an ion exchange process, the counterion or the corresponding base can be exchanged surprisingly easily for hydroxide ions. Thus, after step c), only the base added in solution B, e.g. Ammonia, water and the solvent used in step a) as undesirable by-products, which can be easily removed in a subsequent step e). In particular, the separation of the counterion can be carried out by filtering the reaction solution through an ion exchange resin.
    Since monomers are used as matrix monomers usually having a higher boiling point than the solvent used in step a), the particles can be dispersed from the thus prepared sol in the matrix monomer.
    Thus, it is not necessary to remove the solvent prior to dispersing the fillers in the matrix monomer in step d), which could lead to agglomeration or aggregation of the filler particles. The separation of solvent, water and base can thus be carried out in step e), for example by distillation processes.
    Thus, a nanoparticle-filled matrix monomer dispersion is obtained which, in the present form, can be used as the end product or as the base component in a further formulation as a precursor for a dental filler. In addition, a homogeneous distribution of the mixed oxide particles in the monomer is achieved by the inventive production process, which also has a positive effect on the physical and mechanical properties of the cured composite. The ratio of filler to the matrix monomer as a dispersant depends on the desired solids content of the composite.
    One embodiment provides for the use of acrylates, in particular methacrylates, for example bis-GMA or TEG-DMA as matrix monomer. The use of co-monomers is possible. For example, process parameters, such as, for example, the viscosity of the monomer matrix mixture and the material properties of the polymerized composites, can be influenced by the type and amount of the particular co-monomers used.
    The preparation process provides for the preparation of a nanoparticle dispersion without a detour via a powder intermediate stage. On the one hand, this offers the advantage that the unavoidable formation of agglomerates, which is pronounced in powder production, in particular with nanoparticles, and the associated redispersing step can be circumvented. Furthermore, eliminates the need for handling nanoscale powders safety technology.
    The manufacturing method also makes it possible to set the refractive index of the mixed oxide Si02-M0x by selecting the type of X-ray opaque metal and amount of Metallprecursors used. Thus, an adjustment of the refractive index of the filler to the refractive index of the matrix monomer used is possible. As a result, for example, turbidity effects of the composite can be avoided and its optical properties can be optimized.
    In particular, the use of barium or strontium as radiopaque metal is advantageous both in terms of radiopacity and refractive index adjustment as well as in view of the handling of the respective precursors in the production process. Barium perchlorate or a barium hydroxide partially neutralized with a suitable acid are preferably used as precursors.
    The preparation of the dispersion is preferably carried out as a one-pot synthesis. Thus, the procedural effort is minimized.
    A further development of the production method according to the invention provides for the use of two metal precursors MaXb and M'cXd of different metals M and M '. The ternary mixed oxide formed according to this development has a composition according to the formula SiO 2 -MO x MOy with variable proportions of the individual oxides. According to one embodiment, the ternary mixed oxide contains silicon oxide, barium oxide and strontium oxide.
    Preference is given as a silicon precursor silane according to the formula SiX4 with 4 hydrolyzable groups X selected from the group X = OR, halogen, NR2 (R = alkyl, aryl), H], preferably a tetraalkoxysilane selected from the group consisting of tetramethyl orthosilicate [TMOS, Si (OCH3) 4], tetraethylorthosilicate [TEOS, Si (OC2H5) 4], tetrapropoxysilane [Si (OC3H7) 4] and / or a silane according to the formula RSiX3 with 3 hydrolyzable groups X selected from the group X = OR, Halogen, NR2 (R = alkyl, aryl), H] and a non-hydrolyzable organic side group R used.
    Preferred solvents are low-boiling alcohols, in particular ethanol.
    The dispersions obtained in step e) can be used as a precursor for a dental composite. Another embodiment provides that the dispersions obtained in steps) are mixed or mixed with further components, for example initiators, further monomers or filler particles.
    By polymerization, the dispersions cure to form the corresponding composite. The dispersions can be used, for example, by being filled in dental cavities or applied to the tooth surface. Furthermore, the dispersions can be introduced into a mold and cured.
    DETAILED DESCRIPTION OF THE INVENTION The invention will be explained in more detail below with reference to the following FIGS. 1 to 5 and to the region of the listed exemplary embodiments.
    Brief Description of the Figures [0078] In the drawings:
    1 is a schematic representation of a first embodiment of the Flerstellungsverfahrens,
    2 shows a schematic illustration of a second embodiment of the flanging method, in which the mixed oxide particles have a further surface modification in addition to the copolymerizable group,
    3 shows a schematic representation of the transfer of the dispersion according to the invention into a dental composite,
    Fig. 4 is a schematic representation of the transfer of the dispersion prepared according to FIG. 2 in a dental composite and
    5 shows a schematic representation of the conversion of a dispersion with additional, functionalized mixed oxide particles into a dental composite.
    1 shows a schematic representation of an embodiment of the method according to the invention for producing a corresponding dispersion 10 of nanoscale mixed oxide particles 6 in a monomer matrix 9. In step a), the formation of the sol 3 takes place first. For this, the solutions 1 and 2 are mixed , Solutions 1 and 2 are solutions A and B already described above, solution 1 (solution A) comprising a silicon precursor and a salt of a radiopaque metal M, a sol stabilizer (not shown), and solvent 4 and solution 2 (Solution B) an aqueous base (not shown) and also the solvent 4 contains. The reaction mixture is stirred until completion of particle formation. The sol 3 thus obtained contains nanoscale mixed oxide particles 5 in the solvent 4 and also undesirable reaction products from step a) (not shown). In the subsequent step b), the surface modification of the mixed oxide particles 5 is carried out with a silane 25. In this embodiment, the silane 25 has a formula X3SiA, where the functionality A is a group copolymerizable with the matrix monomer. The group X is a hydrolyzable group and is preferably selected from X = OR, halogen, NR "2 with R" = alkyl, aryl.
    The mixed oxide particles 6 thus obtained have a covalently bonded functionality A which is copolymerizable with the matrix monomer 9 fed in step d). The degree of modification of the functionalized mixed oxide particles 6 can be adjusted via the amount of silane 25 added in step b). In step c), a separation of undesired sol constituents via an ion exchanger. The thus prepared sol 8 is redispersed in matrix monomer 9 in step d). Subsequently, solvent 4, water and base (not shown) are removed and the dispersion 10 is obtained.
    Fig. 2 shows schematically a further embodiment of the manufacturing method. Here, in step b), in addition to the silane 25, a silane 26 with a further, non-polymerizable functionality B is used. The mixed oxide particles 12 thus have in addition to copolymerizable groups A functionalities B. Here, too, modification degrees can be set via the molar amount of the silanes 25 and 26 used.
    FIG. 3 shows a schematic representation of the transfer of a dispersion 10 according to the invention into a corresponding dental composite 16. By irradiation of light of a suitable wavelength, the polymerization of the matrix monomer 9 takes place, so that a resin matrix 18 is obtained. This results in a copolymerization of matrix monomer 9 with the functional groups A of the mixed oxide particles 6, so that in the dental composite 16, the mixed oxide particles 17 are covalently bonded to the resin matrix 18. Depending on the degree of modification of the mixed oxide particles 6a, these can also act as crosslinker 17a.
    4 schematically shows the transfer of a further embodiment of a nanoscale dispersion 19 into a corresponding dental composite 21. The mixed oxide particles 20, 20a of the dispersion have, in addition to copolymerizable groups A, a further functionality B which is unreactive under the polymerization conditions and thus also present in the cured dental composite 21. Thus, the physical and mechanical properties of the dental composite 21 can be influenced by the group B of the mixed oxide particles 22. Thus, for example, modification of the mixed oxide particles with flexible side chains as functionality B counteracts embrittlement of the dental composite 21.
    Fig. 5 shows schematically another possibility for flexibilization of the dental composite. In this embodiment, more mixed oxide particles 23 are added to the sol 4 containing Mischoxidpartikei 6 with a copolymerizable functionality A. The functional group B of the second Mischoxidpartikei 23 is not reactive under the reaction conditions of the polymerization. After the dispersion has hardened, the dental composite 21 thus contains both mixed oxide particles 17 covalently bound to the resin matrix and functionalized mixed oxide particles 20 which are not covalently bonded into the resin matrix 22.
    EXAMPLES Example 1 Dispersion of SiO 2 -BaO Nanoparticles in a Bis-GMA / TEG-DMA Matrix Using Barium Perchlorate as Precursor and Hydroxypropyl Cellulose as Solstabilizer Step a) Particle synthesis Solution A: 8 g anhydrous Barium perchlorate are dissolved in 238 ml of ethanol. To stabilize the solution, 1.2 ml of acety-laceton be added. Subsequently, the solution is added 26.8 ml of TEOS.
    Solution B: 278 ml of ethanol are mixed with 29 ml of a 25% NH 4 OH solution and 3 g of hydroxypropylcellulose (HPC) are added as a sol stabilizer. The solution is stirred until the sol stabilizer has dissolved.
    To start the reaction, solution A is added rapidly to solution B with vigorous stirring. Subsequently, the reaction mixture is stirred for 24 h. As a result of particle formation, the solution gradually becomes cloudy.
    Step b): Surface modification For the silanization of the particles synthesized in step a), 2.8 ml of 3-methacryloxypropyltrimethoxysilane (MPTMS) are added to the reaction solution. The reaction solution is stirred again for 24 h.
    Steps): Separation of the counterion To remove the perchlorate ions present in the reaction mixture, the solution is filtered through a column filled with 50 g of Lewatit M500 OH ion exchanger. The ion exchanger is loaded with hydroxide ions so that during the filtration of the solution, perchlorate ions are removed and exchanged for hydroxide ions.
    Step d): Dispersing the Particles in the Matrix Monomer The reaction solution ion-exchanged in step c) is added to 90 g of a mixture of bis-GMA and TEG-DMA with a mixing ratio of 1: 1.
    Step e): Working Up of the Reaction Solution The components of ammonia, ethanol and water present in the solution are removed from the mixture by vacuum distillation on a rotary evaporator. What remains is a 10% dispersion of the silanized SiO 2 -BaO 2 nanoparticles with a bis-GMA / TEG-DMA as matrix monomer.
    Example 2 Dispersion of SiO 2 -BaO Nanoparticles with a Mixture of Bis-GMA / TEG-DMA as Matrix Monomer Using 3-Methacryloxypropyltrimethoxysilane (MPTMS) as Solvent Stabilizer Step a) and b): Particle synthesis and silanization Solution A: 8 g of anhydrous barium perchlorate are dissolved in 214 ml of ethanol. To stabilize the solution 1.2 ml of acetylacetone are added. Thereafter, 12.3 ml of TEOS are added to the solution. Subsequently, the solution is mixed with 13.1 ml of 3-methacryloxypropyltrimethoxysilane (MPTMS).
    Solution B: 252 ml of ethanol are mixed with 26 ml of a 25% NH 4 OH solution.
    To start the reaction, solution B is added rapidly to solution A with vigorous stirring. Subsequently, the reaction mixture is stirred for 24 h. As a result of particle formation, the solution gradually becomes cloudy.
    Steps): Separation of the counterion To remove the perchlorate ions present in the reaction mixture, the solution is filtered through a column filled with 50 g Lewatit M500 OH ion exchanger. The ion exchanger is loaded with hydroxide ions, so that removed during the filtration of the solution perchlorate ions and replaced in exchange for hydroxide ions.
    Step d): dispersing the particles in the matrix monomer
    权利要求:
    Claims (15)
    [1]
    The reaction solution ion-exchanged in step c) is added to 90 g of a mixture of bis-GMA and TEG-DMA with a mixing ratio of 1: 1. Step e): Working up of the reaction solution The volatile components ammonia, ethanol and water present in the solution are removed from the mixture by vacuum distillation on a rotary evaporator. What remains is a 10% dispersion of the silanized SiO 2 -baO nanoparticles with a bis-GMA / TEG-DMA as matrix monomer. Example 3: Use of Ba (OH) 2 as BaO Precursor Step a) and b): Particle Synthesis and Silanization 220 ml of ethanol are introduced into a reaction vessel and, with stirring, first 12, Add 3 ml of tetraethylorthosilicate and 13.1 ml of 3-methacryloxypropyltrimethoxysilane (MPTMS), then add 1.4 ml of methacrylic acid to stabilize the solution. Finally, the mixture is also treated, while stirring, with 71.5 ml of saturated baryta water (i.e., 4.6% strength aqueous Ba (OH) 2 solution). Solution B: 256 ml of ethanol are mixed with 85 ml of a 2 molar NH 3 solution in ethanol. To start the reaction, solution B is added rapidly to solution A with vigorous stirring. Subsequently, the reaction mixture is stirred for 24 h. As a result of particle formation, the solution gradually becomes cloudy. Steps): Separation of the counterion To remove the methacrylates present in the reaction mixture, the solution is filtered through a column filled with 50 g of Lewatit M500 OH ion exchanger. The ion exchanger is loaded with hydroxide ions, so that removed during the filtration of the solution methacrylates and replaced in exchange for hydroxide ions. Step d): Dispersing the Particles in the Matrix Monomer To the reaction solution ion-exchanged in step c) is added 40 g of a mixture of bis-GMA and TEG-DMA with a mixing ratio of 1: 1. Steps): Working up of the reaction solution The volatile components ammonia, ethanol and water present in the solution are removed from the mixture by vacuum distillation on a rotary evaporator. What remains is a 20% dispersion of the silanized SiO 2 -to-BaO nanoparticles with a bis-GMA / TEG-DMA as matrix monomer. Example 4: Synthesis of a commercial system with SiO 2 particles as Comparative Example A commercially available sol of 50% by weight SiO 2 in TEG-DMA is mixed with bis-GMA in a ratio of 2: 1. The resulting dispersion has a solids content of 33%. Example 5: Polymerization of the Nanocomposites The dispersions obtained in Examples 1 to 4 are mixed with a mixture of camphorquinone and ethyl dimethylaminobenzoate and then cured under UV light. Subsequently, the optical properties of the cured, i. polymerized composites on a Hunterlab Colorquest colorimeter. The results are summarized in Table 1. Table 1: Summary of optical properties

    claims
    A dispersion for use as a precursor for a dental composite containing a filler and a matrix monomer having at least one polymerizable group, said filler comprising nanoscale mixed oxide particles, said mixed oxide particles containing silicon and at least one radiopaque metal M having an atomic number Z> 36 in oxidic form and wherein the mixed oxide particles contain at least one covalently bonded, polymerizable group which can be copolymerized with the polymerizable group of the matrix monomer.
    [2]
    2. Dispersion according to the preceding claim, wherein the matrix monomer at least one acrylate, preferably a methacrylate, more preferably a methacrylate selected from the group methyl, ethyl, butyl, benzyl, furfuryl or phenyl (meth) acrylate, bisphenol A-di (meth) acrylate, bis-GMA, ezhoxyliert.es bisphenol A di (meth) acrylate, UDMA, di-, tri- or tetraethylene glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol tetra (meth) acrylate , Butanediol di (meth) acrylate, 1,10-decanediol di (meth) acrylate or 1,12-dodecanediol di (meth) acrylate or a mixture thereof.
    [3]
    3. Dispersion according to one of the preceding claims 1 to 2, wherein the mixed oxide silicon and a metal M having an atomic number Z> 36 in oxidic form according to the formula SiO 2 -M0x and / or a metal M 'with an atomic number Z> 36 in oxidic Contains form according to the formula Si02-M0x-MOy.
    [4]
    4. Dispersion according to one of the preceding claims 1 to 3, wherein the filler particles have an average particle size in the range of 5 to 100 nm, preferably from 10 to 70 nm and particularly preferably from 20 to 50 nm.
    [5]
    5. Dispersion according to one of the preceding claims 1 to 4, wherein the polymerizable group of the mixed oxide particles of the filler is a vinylic group, in particular an acrylate, preferably a methacrylate, more preferably a 3-methacryloxypropyl - (MPTM) group.
    [6]
    6. Dispersion according to one of the preceding claims 1 to 5, wherein the filler content is 10 to 70 wt .-% of the dispersion, preferably 20 to 60 wt .-% of the dispersion and particularly preferably 30 to 50 wt .-% of the dispersion.
    [7]
    7. dental composite obtained by curing the dispersion according to any one of claims 1 to 6.
    [8]
    8. A process for the preparation of a dispersion, wherein the dispersion contains a nanoscale mixed oxide having at least one polymerizable group as a filler and a matrix monomer and is obtained by sol formation, and subsequent curing of the precursor, characterized in that a) nanoscale composite oxide particles of SiO 2 with a radiopaque metal oxide of a metal M with an atomic number Z> 36 starting from at least one silicon precursor and a metal salt MaXb or a metal hydroxide Ma (OH) b, wherein the metal hydroxide is at least partially neutralized by addition of an organic acid HA; b) the mixed oxides prepared in step a) are functionalized by means of the polymerizable groups, c) the counterion X or the corresponding base of the organic acid used in step a) is removed from the reaction solution, d) the filler particles functionalized in step b) Dispersed matrix monomer, e) the dispersion is prepared, wherein in step a) first a solution A and a solution B is provided, wherein the solution A is a solvent, an organic silicon precursor and a radiopaque metal M in salt form or as a hydroxide and the Solution B, a solvent, an aqueous base and a sol stabilizer and the solution B is added with stirring to the solution A and the reaction solution is stirred to complete the particle formation, wherein subsequently added in step b) for functionalization, a silane having a polymerizable group and wherein in step e) solvent l, water and base are removed.
    [9]
    9. The method according to claim 8, wherein the solution A as a silicon precursor silane according to the formula SiX4 with 4 hydrolyzable groups X selected from the group X = OR, halogen, NR "2 R" = alkyl or aryl, preferably a tetraalkoxysilane selected from Group consisting of tetramethyl orthosilicate [TMOS, Si (OCH3) 4], tetraethyl ortho-silicate [TEOS, Si (OC2H5) 4], tetrapropoxysilane [Si (OC3H7) 4] and / or a silane according to the formula RSiX3 with 3 hydrolyzable groups X selected from the group X = OR, halogen, NR "2 R" = alkyl, aryl and a non-hydrolyzable organic side group R is used.
    [10]
    10. The method according to any one of claims 8 to 9, wherein the solution A, a further metal salt M'cXb or hydroxide of a radiopaque metal M 'with an atomic number Z> 36 is added.
    [11]
    11. The method according to any one of claims 8 to 10, wherein in the solutions A and B, an alcohol, preferably an alcohol selected from the group consisting of ethanol, methanol or isopropanol, is used as the solvent.
    [12]
    12. The method according to any one of claims 8 to 11, wherein in solution A as the sol stabilizer, a silane with a sterically demanding organic radical and / or a protective colloid, preferably a cellulose, particularly preferably hydroxypropylcellulose is used.
    [13]
    13. The method according to any one of claims 8 to 12, wherein in step b) additionally a silane with an organic, non-copolymerizable radical, preferably a silane of the formula RSiX3 or RR'SiX2 with hydrolyzable groups X selected from the group X = OR, halogen , NR "2 with R" = alkyl, aryl, and non-hydrolyzable organic radicals R and / or R 'is used.
    [14]
    14. Use of the dispersion according to any one of claims 1 to 6 as a precursor for a dental composite.
    [15]
    15. Use of the dental composite according to claim 7 for the production of dental fillings or dental prostheses.
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    同族专利:
    公开号 | 公开日
    US9724275B2|2017-08-08|
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    KR102226777B1|2021-03-11|
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    法律状态:
    2017-10-13| PK| Correction|Free format text: BERICHTIGUNG ERFINDER |
    2017-12-15| PK| Correction|Free format text: BERICHTIGUNG: ERFINDER UND PATENTANSPRUECHE. |
    优先权:
    申请号 | 申请日 | 专利标题
    DE102013100546.2A|DE102013100546A1|2013-01-18|2013-01-18|Dispersions of nanoscale dental glass particles and process for their preparation|
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