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    • 专利摘要:
    raw block for machining dental prosthesis, process for its production and use. the present invention relates to a rough block for machining colored zirconia ceramic dental prosthesis having fluorescent properties, production processes of that rough block for machining and uses thereof, in particular for the production of zirconia ceramic dental restorations. the rough block for dental prosthesis machining having a shape that allows the rough block for dental prosthesis machining to be connected or fixed to a machining device, the rough block for dental prosthesis machining comprises a porous zirconia material, being that the porous zirconia material comprises zr oxide calculated as zro2: from about 80 to about 97% by weight, al oxide calculated as al2o3: from about 0 to about 0.15% by weight, oxide of y calculated as y2o3: from about 1 to about 10%, by weight, bi oxide calculated as bi2o3: from about 0.01 to about 0.20%, by weight, tb oxide calculated as tb2o3: from about 0.01 to about 0.8% by weight, and optionally one or two of the following oxides: er oxide calculated as er2o3: from about 0.01 to about 3.0% by weight, mn oxide calculated as mno2: from about 0.0001 to about 0.08% by weight, and the porous zirconia material does not comprise fe oxide calculated as fe2 03 in an amount of more than about 0.01%, by weight, with% by weight, with respect to the weight of the porous zirconia material.
    公开号:BR112016012730B1
    申请号:R112016012730-7
    申请日:2014-12-03
    公开日:2021-04-13
    发明作者:Michael Jahns；Hans R. Schnagl
    申请人:3M Innovative Properties Company；
    IPC主号:
    专利说明:

    Field of the Invention
    [001] The invention relates to a rough block for machining dental prosthesis ("dental mill blank") of colored zirconia ceramic having fluorescent properties, production processes of this rough block for machining and uses of it, in particular for the production of dental restorations of zirconia ceramic. Background of the Invention
    [002] The rough blocks for machining dental prosthesis made of zirconia ceramic are described in several documents and are also available for sale. The rough blocks for machining dental prosthesis from zirconia ceramic are typically used for the production of dental restorations (for example, crowns and bridges) by a machining process. The zirconia material from which the rough block for machining dental prosthesis is typically in a pre-sintered and porous stage that facilitates its machining. The obtained dental article is then sintered to its final density before being placed in the patient's mouth. Pure zirconia, however, is white and does not match the natural tooth color in a patient's mouth. To address this problem, machined zirconia material is typically treated with certain dyeing solutions prior to sintering. Most dyeing solutions, which are also available for sale, contain iron as a dye ion. Iron ions are apparently perfect for obtaining the desired tooth staining.
    [003] WO 2012/125885 A1 (3M) relates to a ceramic dental article comprising ZrO2 and Al2O3 and at least one component comprising Mn, Er or mixtures thereof. It is stated that the ceramic article demonstrates an improvement in aesthetic appearance compared to state-of-the-art ceramic articles.
    [004] WO 2013/022612 A1 (3M) refers to a dyeing solution to selectively treat the surface of dental ceramics, the solution comprising a solvent, an effect agent and a complexing agent, the effect being caused by the effect agent is dyeing, providing fluorescence or a combination of both. Metals considered useful include Fe, Mn, Er, Pr, Co and Bi.
    [005] US patent 2012/0012789 A1 (Yamada et al.) Describes a fluorescent zirconia material that comprises at least one type of Y2SiO5: Ce, Y2SiO5: Tb, (Y, Gd, Eu) BO3, Y2O3: EU, YAG: CE, ZnGa2O4: Zn and BaMgAl10O17: EU.
    [006] US patent 2008/0303181 A1 (Holand et al.) Describes a dental material toned to match natural dentition comprising ZrO2 stabilized with cerium oxide, a dyeing agent comprising one or more of Fe, Pr, Tb, Er, Nd, Eu, Yb and M, oxides thereof and combinations thereof.
    [007] US patent 2012/0214134 A1 (Khan et al.) Refers to a dental article that includes yttragonal stabilized tetragonal zirconia polycrystalline ceramics and up to about 0.15% by weight of one or more dyeing agents. one or more among: Fe, Er, Co, Pr, Tb, Cr, Nd, Ce, V, Eu, Ho, Ni and Cu, oxides thereof and combinations thereof.
    [008] The patent FR 2781366 A1 (Norton Desmarquest Fine Ceramics) describes a ceramic composition of yttrium-stabilized zirconium dioxide for dental prostheses stained with a mixture of pigments of iron oxide, bismuth oxide and cerium oxide.
    [009] US patent 8,541,329 B2 (Ivoclar) refers to compositions based on ZrO2 and raw blocks of simple and multiple color made of oxide ceramics. A preferred composition based on ZrO2 further contains Pr calculated as Pr2O3 in an amount of 0.0001 to 0.01% by weight, Fe calculated as Fe2O3 in an amount of 0.005 to 0.5% by weight, Tb calculated as Tb2O3 in an amount of 0.0001 to 0.1%, by weight, and Mn calculated as Mn2O3 in an amount of 0.0001 to 0.1%, by weight. And WO 2014/164199 A1 (3M) refers to a solution to color and fluoresce a dental zirconia article, the solution comprising a solvent, a coloring agent comprising ions selected from Tb, Er, Pr, Mn and combinations of these, a fluorescent agent comprising Bi, the solution not comprising Fe ions in an amount above about 0.05% by weight relative to the weight of the solution.
    [010] However, there is still room for improvement specifically with regard to requirements to be met that relate to modern dental materials. There is a growing demand from patients and dentists for aesthetic and durable dental restorations. Description of the Invention
    [011] An objective of the invention described in the present text can be seen in the supply of a rough block for machining dental prosthesis that can be used to produce highly aesthetic dental restorations. The dental restoration must not only match the natural color of the teeth, but must also have a shiny appearance. This object can be solved by the rough block for machining dental prosthesis described in the present text and processes related to its production.
    [012] In one embodiment, the present invention features a rough block for machining dental prosthesis that comprises a porous zirconia material and optionally means for connecting it to a machining device, the porous material of zirconia comprising - oxide of zirconia Zr calculated as ZrO2: from about 80 to about 97% by weight, - Al oxide calculated as Al2O3: from about 0 to about 0.15% by weight, - Y oxide calculated as Y2O3: from about 1 to about 10% by weight - Bi oxide calculated as Bi2O3: from about 0.01 to about 0.20% by weight - Tb oxide calculated as Tb2O3: from about 0, 01 to about 0.8% by weight, and optionally one or two of the following oxides: - Er oxide calculated as Er2O3: from about 0.01 to about 3.0% by weight, - Mn oxide calculated as MnO2: from about 0.0001 to about 0.08%, by weight,%, by weight, with respect to the weight of the porous zirconia material, the porous zirconia material does not comprise Fe oxide calculated o as Fe2O3 in an amount of more than about 0.01% by weight, or more than about 0.005 or more than about 0.001% by weight.
    [013] Dental prosthetic machining blocks generally have a shape that allows the dental prosthesis machining block to be connected or attached to a machining device.
    [014] The invention also relates to a process for the production of a crude block for machining dental prostheses as described in this text, the process comprising the steps of - mixing the powders of the respective oxides to obtain a powder mixture - and press the powder mixture into the shape of a rough block for machining dental prostheses.
    [015] Alternatively, the rough block for machining dental prosthesis can be produced by a process that comprises the steps of heat treatment or calcination of an airgel.
    [016] In addition, the present invention relates to a process for the production of a dental zirconia article, the process comprising the steps of - providing a rough block for machining dental prosthesis that comprises a porous zirconia material as described in this text, - placing the rough block for machining dental prosthesis in a machining device, - machining the porous zirconia material.
    [017] The invention also relates to a dental article obtainable by the process described in the present text. The term "dental article" means any article that is to be used in the dental or dental field, especially for the production of or as a dental restoration, a model of tooth and its parts. Examples of dental articles include crowns (including monolithic crowns), bridges, fillings, restorations, veneers, veneers, transfer crowns, bridge and crown structures, implants, supports, dental devices (for example, brackets, mouth tubes, clamps and buttons ), monolithic dental restorations (ie restorations that do not need to be veneered) and parts thereof.
    [018] The surface of a tooth is not considered a dental article.
    [019] A dental article should not contain components that are harmful to the patient's health and, therefore, it should be free of risky and toxic components that have the ability to migrate out of the dental article. “Crude block for dental prosthesis machining” means a solid block (three-dimensional article) of material from which a dental article, dental workpiece, dental support structure or dental restoration can and typically must be machined in any subtractive process, for example , in addition to machining, also by grinding, drilling, etc. A rough block for machining dental prosthesis has a geometrically defined shape and comprises at least one flat surface. A so-called “free-form surface” is not referred to as “geometrically defined”. In this regard, the shape of a dental restoration (for example, crown or bridge) itself is not called a rough block for machining dental prostheses. A rough block for dental machining can have a size of about 20 mm to about 30 mm in two dimensions, for example, it can have a diameter in that range, and it can have a certain length in a third dimension. A crude block for making a single crown can have a length of about 15 mm to about 30 mm, and a crude block for making bridges can have a length of about 40 mm to about 80 mm. A typical size of a rough block used to manufacture a single crown has a diameter of about 24 mm and a length of about 19 mm. In addition, a typical size of a crude block used for making bridges has a diameter of about 24 mm and a length of about 58 mm. In addition to the dimensions mentioned above, a rough block for machining dental prostheses can also be shaped like a cube, cylinder or cuboid. Larger rough blocks for machining prostheses can be advantageous if more than one crown or bridge is to be manufactured from a single rough block. For these cases, the diameter or length of a crude block of cylindrical or cuboid shape can be in the range of about 100 to about 200 mm, with a thickness being in the range of about 10 to about 30 mm.
    [020] “Zirconia article” means a three-dimensional article in which at least one of the dimensions x, y, z is at least about 5 mm, the article being composed of at least about 80% or at least about 90 or at least about 95% by weight of zirconia.
    [021] “Ceramics” means an inorganic, non-metallic material that is produced by the application of heat. Ceramics are rigid, porous and brittle and, in contrast to glass or glass ceramics, exhibit an essential and purely crystalline structure.
    [022] "Crystalline" means a solid composed of atoms positioned in a periodic pattern in three dimensions (that is, it has a long-range crystal structure as determined by X-ray diffraction). Crystal structures include cubic, monoclinic, tetragonal zirconia and mixtures thereof.
    [023] “Monolithic dental restoration” shall mean a ceramic dental article on the surface of which no coating (the color of the teeth) or veneer has been fixed. That is, the monolithic dental restoration is essentially comprised only of a material composition. However, if desired, a thin shiny finish layer can be applied.
    [024] “Glass” means an inorganic non-metallic amorphous material that is thermodynamically a sub-cooled and frozen melt material. Glass refers to a transparent, brittle, hard solid. Typical examples include sodium-calcium glass (soda-lime) and borosilicate glass. A glass is an inorganic fusion product that has been cooled to a rigid condition without crystallization. Most glasses contain silica as their main component and a certain amount of glass former. The porous ceramic dental material described in this text does not contain glass.
    [025] “Vitroceramics” means an inorganic non-metallic material where one or more crystalline phases are surrounded by a glass phase so that the material comprises a glass material and a ceramic material in a combination or mixture. It is formed like glass, and then produced to partially crystallize by heat treatment. Glass ceramics can refer to a mixture of oxides of lithium, silicon and aluminum.
    [026] The porous dental material described in this text does not contain glass ceramic. A "powder" means a dry volume composed of a large number of fine particles that can flow freely when agitated or tilted. A "particle" means a substance that is a solid and has a shape that can be geometrically determined. The shape can be regular or irregular. Particles can typically be analyzed for, for example, grain size and grain size distribution.
    [027] "Density" means the ratio of an object's mass and volume. The density unit is typically g / cm3. The density of an object can be calculated, for example, by determining its volume (for example, when calculating or applying Archimedes' principle or method) and measuring its mass.
    [028] The volume of a sample can be determined based on the external dimensions as a whole of the sample. The sample density can be calculated from the measured sample volume and the sample mass. The total volume of the ceramic material can be calculated from the mass of the sample and the density of the material used. The total volume of cells in the sample is assumed to be the remainder of the sample volume (100% less the total volume of material).
    [029] An article is classified as an “absorbent” if it is able to absorb a certain amount of a liquid, comparable to a sponge. The amount of liquid that can be absorbed depends, for example, on the chemical nature of the article, the viscosity of the solvent, the porosity and the pore volume of the article. For example, a pre-sintered ceramic article, which is an article that has not yet been sintered to full density, is able to absorb a certain amount of liquid. Absorption of liquids is typically only possible if the article has an open pore structure.
    [030] A "porous material" refers to a material that comprises a partial volume that is formed by voids, pores or cells in the technical field of ceramics. Consequently, a “open cell” structure of a material is sometimes called an “open pore” structure, and a “closed cell” material structure is sometimes called a “closed pore” structure. It can also be seen that instead of the term “cell”, sometimes “pore” is used in this technical field. The categories of material structure “open cells” and “closed cells” can be determined for different porosities measured in samples of different materials (for example, using a “Poremaster 60-GT” mercury from Quantachrome Inc., USA) according to DIN 66133. A material that has an open cell or open pore structure can be passed through, for example, gases.
    [031] Typical values for an “open cell” material are typically about 15% and about 75% or between about 18% and about 75% or between about 30% and about 70%, or between about between 34% and about 67% or between about 40% and about 68% or between about 42% and about 67%.
    [032] The term “closed cell” refers to a “closed porosity”. Closed cells are cells that are not accessible from the outside and cannot be infiltrated by gases under ambient conditions. The "average connected pore diameter" means the average open cell pore size of a material. The average connected pore diameter can be calculated as described in the Examples section.
    [033] The term "calcination" refers to a process of heating solid material to expel at least 90 percent by weight of volatile chemically bound components (eg, organic components), (in comparison to, for example, drying, in which physically bound water is expelled by heating). Calcination is carried out at a temperature below the temperature required to conduct a pre-sintering step. The terms "sintering" or "burning" are used interchangeably. A pre-sintered ceramic article shrinks during a sintering step, that is, if a suitable temperature is applied. The sintering temperature to be applied depends on the ceramic material chosen. For ZrO2-based ceramics, a typical sintering temperature range is about 1100 ° C to about 1550 ° C. Sintering typically includes the densification of a porous material to a less porous material (or a material that has fewer cells) that has a higher density, in some cases, sintering may also include changes in the material phase composition (eg example, a partial conversion from an amorphous phase to a crystalline phase).
    [034] “Isotropic sintering behavior” means that the sintering of a porous body during the sintering process occurs essentially invariant with respect to the x, y and z directions. “Essentially invariant” means that the difference in sintering behavior with respect to the x, y and z directions is in the range of no more than about +/- 5% or +/- 2% or +/- 1%.
    [035] "Solution" means a solvent-containing composition with soluble components dissolved in itself. The solution is liquid at room temperature.
    [036] "Solvent" means any solvent that can dissolve the dyeing agent. The solvent must be chemically stable enough if combined with the dyeing agent. That is, the solvent must not be decomposed by the other components present in the composition.
    [037] "Soluble" means that a component (solid) can be completely dissolved in a solvent. That is, the substance has the ability to form individual molecules (such as glucose) or ions (with sodium cations or chlorine anions) when dispersed in water at 23 ° C. The solution process, however, can take some time, for example, it may be necessary to stir the composition for a few hours (for example, 10 or 20 hours).
    [038] “Dyeing ions” means ions that have an absorption in the spectrum visible to the human eye (for example, from about 380 to about 780 nm), which result in a tinted solution (visible to the human eye), if the dyeing ions are dissolved in water (eg 0.6 mol / l) and / or cause a dyeing effect on the zirconia article that was treated with the dyeing solution and then sintered.
    [039] A "fluorescent agent" means an agent that demonstrates fluorescence in the region of visible light (about 380 to about 780 nm).
    [040] "Sol" refers to a continuous liquid phase containing discrete particles having sizes in a range from 1 nm to 100 nm.
    [041] "Diafiltration" is a technique that uses ultrafiltration membranes to completely remove, replace, or lower the concentration of salts or solvents from solutions containing organic molecules. The process selectively uses permeable (porous) membrane filters to separate solution components and suspensions based on their molecular size.
    [042] The term “airgel” will mean a low-density three-dimensional solid (ie less than 20% of theoretical density). An airgel is a porous material derived from a gel, in which the liquid component of the gel has been replaced with a gas. Solvent removal is done, often in supercritical conditions. During this process the mesh does not shrink substantially and a highly porous, low density material can be obtained.
    [043] The term “tubular reactor” refers to the portion of a continuous hydrothermal reactor system that is heated (that is, the heated zone). The tubular reactor can be in any suitable shape. The shape of the tubular reactor is often selected based on the desired length of the tubular reactor and the method used to heat the tubular reactor. For example, the tubular reactor can be straight, U-shaped or spiral-wound. The inner portion of the tubular reactor may be empty or may contain deflectors, balls, or other known mixing techniques.
    [044] "Foundry" means a manufacturing process by which a liquid material (eg solution or dispersion) is poured into a mold, which contains a hollow cavity of the desired shape, and is then left to solidify.
    [045] By "machining" we can say grinding, crushing, cutting, carving or formatting a material by a machine. Lamination is usually faster and more cost-effective than grinding. A "machinable article" is an article that has a 3-dimensional shape and that has sufficient strength to be machined.
    [046] "Ambient conditions" means the conditions under which the solution of the invention is normally submitted during storage and handling. Ambient conditions can, for example, be a pressure of about 90 to about 110 kPa (about 900 to about 1,100 mbar), a temperature of about 10 to about 40 ° C and a relative humidity of about 10 to about 100%. In the laboratory, ambient conditions are set at about 20 to about 25 ° C and about 100 to about 102.5 kPa (about 1000 to about 1025 mbar).
    [047] A composition is "essentially or substantially free of" a certain component, if the composition does not contain said component as an essential feature. Thus, said component is not intentionally added to the composition as such or in combination with other components or ingredients of other components. A composition essentially free of a certain component usually contains absolutely nothing of the same. However, sometimes, the presence of a small amount of said component is not preventable, for example, due to the impurities contained in the raw materials used.
    [048] As used in the present invention, "one", "one", "o", "a", "at least one", "at least one", "one or more" and "one or more" are used interchangeably. The terms "understand" or "contain" and variations thereof do not have a limiting meaning in the way in which these terms appear in the description and claims. As also used in the present invention, the mention of numerical ranges with extremes includes all numbers contained in that range (for example, 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, 5 , etc.).
    [049] Adding an “(s)” to a term means that the term must include the singular and plural form. For example, the term "additives (s)" means an additive and more additives (for example, 2, 3, 4, etc.).
    [050] The term "comprises" also includes the more limited expression "consists essentially of" and "consists of".
    [051] Except where otherwise noted, all numbers that express quantities of ingredients, measurement of physical properties such as those described below and so on used in the specification and in the claims should be understood to be modified in all instances by the term “ about".
    [052] The problem with combining tooth-like color and tooth-like fluorescence so far was maintaining a high amount of bluish fluorescence while the natural tooth is usually yellowish or brown in color, thereby eliminating much of the blue color.
    [053] This problem, however, cannot be completely avoided. However, with special combinations of dyeing ions, the fluorescence effect can be optimized and a visible fluorescence in darker colors can be achieved more than before. Bismuth has been found to be a good additive to add fluorescence to dental zirconia, because it produces a naturally-looking fluorescence spectrum with maximum emission of blue light, but also with emission of green, yellow, orange and red light. Iron, however, as a dyeing agent, with its wide absorption bands, even if present in very low concentrations, eliminates almost all the fluorescence provided by the bismuth. The terbium, on the other hand, has narrower absorption bands and greater production of fluorescence light can be achieved. Thus, a combination of terbium and bismuth is sometimes preferred. The composition of tinting ions and bismuth ions described in the present text to be used for the manufacture of dental zirconia material is therefore advantageous in the sense that more traces of fluorescence in the material even if the zirconia material is tinted with darker colors .
    [054] In this way, it was discovered that the rough block for machining dental prostheses described in this text not only facilitates the manufacture or machining of restorations with toothache but also gives tooth-colored restorations a shiny and lustrous appearance. It has been found that by incorporating the bismuth ions into the rough block material for dental prosthesis machining, the rough block for dental prosthesis machining can be supplied with fluorescent properties. This, however, is only possible if there is nothing but just traces of iron ions present. In addition, it has been found that using at least one of the three ions of erbium, terbium and manganese dyeing, it is possible to provide rough blocks for machining dental prostheses in almost all tooth colors (according to the Vita ™ color guide). Thus, the processes for producing the raw block for machining dental prostheses described in this text are particularly advantageous from an economic point of view as only a limited number of oxides are required. It has also been discovered that the machined dental article (s) of the rough porous block (s) for dental prosthesis machining can be sintered to final density without negatively affecting physical and mechanical properties, such as bending force and / or distortion.
    [055] If desired, the respective dyeing oxides can be supplied in the form of batches of color which can further facilitate the mixing step.
    [056] In certain embodiments, the porous zirconia material meets at least one or more, sometimes all of the following parameters: (a) showing an N2 absorption and / or desorption isotherm with a hysteresis loop; (b) show an N2 absorption and desorption of isotherm type IV according to the IUPAC classification and a hysteresis loop; (c) show an N2 type IV absorption and desorption isotherm with an H1 type hysteresis loop according to the IUPAC classification; (d) showing an N2 type IV adsorption and desorption isotherm with a H1 type hysteresis loop according to the IUPAC classification in a p / p0 range of 0.70 to 0.95; (e) average diameter of the connected pore: from about 10 to about 100 nm or from about 10 to about 80 nm or from about 10 to about 70 nm or from about 10 to about 50 nm or about 15 to about 40; (f) average grain size: less than about 100 nm or less than about 80 nm or less than about 60 nm or about 10 to about 100 or about 15 to about 60 nm; (g) BET surface: from about 10 to about 200 m2 / g or from about 15 to about 100 m2 / g or from about 16 to about 60 m2 / g; (h) Biaxial flexural strength: from about 10 to about 40 or from about 15 to about 30 MPa; (i) dimension x, y, z: at least about 5 or at least about 10 or at least about 20 mm; (j) Vickers hardness: from about 25 (HV 0.5) to about 150 or from 35 to about 140 (HV 1).
    [057] It has been found that a combination of the following characteristics is particularly beneficial: (a) and (h), or (a) and (b) and (h), or (b) and (c), or (c), (e), (g) and (h). If desired, the characteristics above can be determined as described in the Examples section. Surprisingly, it was found that material showing an N2 adsorption and / or desorption of type IV isotherm (according to the IUPAC classification) and / or desorption adsorption isotherms with a hysteresis loop (especially in a p / p0 range of 0, 70 to 0.95) are particularly suitable.
    [058] The BET surface of porous zirconia materials described in the prior art is typically comprised in a range of 2 to 9 m2 / g, 2 / g, whereas the BET surface of the porous zirconia materials described in this text is, preferably above 10 m2 / g. The average grain size of the zirconia particles in the porous zirconia article described in this text is small compared to the average grain size of the commercially available prosthetic mill blanks.
    [059] A small grain size can be beneficial in that it typically leads to a more homogeneous material (from a chemical perspective), which can also result in more homogeneous physical properties. Thus, the porous zirconia material described in this text can have a unique combination of characteristics, which facilitates a reliable production of highly aesthetic ceramic articles.
    [060] Useful ranges for the x, y and z dimensions include from about 5 to about 300 or from about 8 to about 200 mm. It has been found to be beneficial for certain properties if the porous zirconia material has a certain average connected pore diameter. The average connected pore diameter must be in a specific range. It shouldn't be too small and it shouldn't be too big either. Due to the nanoscale particle size and specific average connected pore diameter of the material used to produce the porous zirconia ceramic material of the rough block for dental prosthesis machining, this material has a different sintering behavior compared to the zirconia ceramic material of blocks for machining dental prostheses that are commercially available (eg LAVA ™ Frame from 3M ESPE) and other zirconia ceramics available in the dental market typically being produced by compacting and pressing zirconia powder (eg 3Y- zirconia powder) TZP by Tosoh Comp.).
    [061] The Vickers hardness of the material is typically in a specific range. If the Vickers hardness of the material is too low, the machining capacity could drop in quality (edge splintering of the workpiece) as well as in the ease of manual rework to individualize the frame of a dental restoration or a monolithic restoration as well. If the Vickers hardness of the material is too high, the wear of the machining tools can increase in an uneconomical range and the tool could break and destroy the workpiece. The biaxial flexural strength of the material is also typically in a specific range. It has been found that if the biaxial flexural strength of the material is too low, the material tends to crack during the lamination process or during manual finishing by a dental technician.
    [062] On the other hand, if the biaxial flexural strength of the material is too high, processing of the material by a laminating machine is often not possible with reasonable efforts. The used laminating tool or laminated material often tends to shatter or break. In this case, the molding of the material would have to be done by grinding, for example, using a Cerec ™ grinding machine (Sirona).
    [063] It has been found that a rough block for dental prosthesis machining having the characteristics described above is better machinable than the rough blocks for dental prosthesis machining available for sale, for example, produces less dust during the machining process.
    [064] The porous zirconia material of the rough block for machining dental prosthesis comprises - Zr oxide calculated as ZrO2: from about 80 to about 97% by weight, or from about 85 to about 95%, in weight, - Al oxide calculated as Al2O3: from about 0 to about 0.15% by weight, or from about 0 to about 0.10% by weight, - Y oxide calculated as Y2O3: from about 1 to about 10% by weight, or from about 4 to about 8% by weight, - Bi oxide calculated as Bi2O3: from about 0.01 to about 0.20% by weight , or from about 0.03 to about 0.15% by weight, - Tb oxide calculated as Tb2O3: from about 0.01 to about 0.8% by weight, or about 0, 01 to about 0.05%, by weight, and one or two of the following oxides: - Er oxide calculated as Er2O3: from about 0.01 to about 3.0%, by weight, or from about 0 .01 to about 2.0% by weight - Mn oxide calculated as MnO2: from about 0.0001 to about 0.08% by weight, or from about 0.001 to about 0.01% , by weight,% by weight , in relation to the weight of the porous zirconia material.
    [065] The following dye oxide combinations present in the zirconia material together with Bi2O3 have been found to be particularly useful: MnO2 and Tb2O3, Er2O3 and Tb2O3, where the combination of Er2O3 and Tb2O3 is sometimes preferred to obtain a better or enhanced color to the tooth. It is preferable that iron ions are absent or essentially absent. Thus, the zirconia material is essentially free of iron ions. However, sometimes due to production processes, it is inevitable that traces of iron ions are still present in the material. If, however, the iron ions content (calculated as oxide) is above the ranges described in this text, the desired shiny and shiny appearance of the dental article cannot be achieved properly. Without wishing to be bound by a certain theory, it is believed that using iron as a dyeing agent, the UV light needed to start fluorescence or the blue fluorescence light emitted, or both are being absorbed by the iron ions and thereby lost to the desired visual appearance.
    [066] According to another modality, the zirconia material is also essentially free of all or some of the following oxides: Fe, V, Mo, Cr, Co, Cu, Pr.
    [067] That is, these oxides are typically absent. Traces of a maximum of 0.01% by weight or a maximum of 0.005% by weight or a maximum of 0.001% by weight with respect to the weight of the porous zirconia material may, however, be permitted.
    [068] If traces are present, they are present in the following quantities: Fe oxide calculated as Fe2O3: less than about 0.01% by weight, or less than about 0.001% by weight, Cr calculated as Cr2O3: less than about 0.01% by weight or less than about 0.001% by weight Cu oxide calculated as CuO: less than about 0.01% by weight or less than about 0.001% by weight, the oxide of V calculated as V2O5: less than about 0.01% by weight, or less than about 0.001% by weight, the oxide of Mo calculated as Mo2O3: less than about 0.01% by weight or less than about 0.001% by weight Pr oxide calculated as Pr2O3: more than about 0.01% by weight or less than about 0.001% by weight weight,%, by weight, with respect to the weight of the porous zirconia material.
    [069] The porous zirconia material of the rough block for machining dental prosthesis is usually in the shape of a disk or block (for example, cuboid, cylinder). The rough block for dental prosthesis machining has a shape that allows the rough block for machining to be connected or attached to a machining device. Suitable formats are block or disk. Connecting or fixing the rough block for machining dental prosthesis to a machining device, especially to the clamping device of that device, can also be done by providing the rough block with suitable means, therefore. Suitable means include groove (s), recess (s), structure (s), notch (s), punch (s) and combinations thereof. In another embodiment, the rough block for machining dental prosthesis is fixed in or contained in a retention device. The retaining device containing the rough block for machining dental prostheses can then function as a means for fixing the rough block on a machining device.
    [070] The fixation of the raw block for machining prostheses in a retention device can be carried out by fixing, gluing, screwing and combinations thereof. Useful restraint devices include frames (open and closed) or tips. The use of a retention device can facilitate the production of the dental article with a machining device.
    [071] Examples of useful restraint devices are described in US 8,141,217 B2 (Gubler et al.), WO 02/45614 A1 (ETH Zurich), DE 203 16 004 U1 (Stuehrenberg), US 7,985,119 B2 (Basler and others) or WO 01/13862 (3M). The content of those documents which relate to the description of the retention device is hereby incorporated by reference.
    [072] According to one modality, the porous zirconia material of the rough block for machining dental prosthesis can be obtained through a process that includes the steps of - mixing the powders of the respective oxides to obtain a powder mixture and - press the powder mixture.
    [073] Mixing the oxide powders can be done by shaking the powders or placing the powders in a mill (eg ball mill) and machining the powders until a powder mixture is obtained. Other possible mixing equipment may include screens or granulators.
    [074] To facilitate the pressing step (s), pressing aids can be added, if desired. Suitable pressure aids include binders, lubricating additives and mixtures thereof. If desired, these aids can be added to the zirconia oxide powder being the main component of the powder mixture. Suitable metal oxide powders are available for sale from a number of suppliers, including Tosoh Company (Japan). If desired, other dye oxides (for example, MnO2 and / or Er2O3) can be added in the desired amounts alone or as a mixture of two or three of the oxides (i.e., as a batch of dye oxide powder). The powder mixture is then placed in a mold and pressed into the shape of a rough block for machining dental prostheses. The pressure to be applied is typically in the range of about 150 to about 200 MPa. Alternatively, the applied pressure is adjusted so that the pressed ceramic body reaches a certain density, for example, in the case of a zirconia ceramic, a density of about 2.8 g / cm3 to about 3.2 g / cm3. The article obtained after pressing the powder mixture can be machined or sliced to any desired shape.
    [075] According to another modality, the porous zirconia material of the rough block for machining dental prosthesis can be obtained by a process that comprises the step of heat treatment or calcination of a zirconia airgel. In addition to zirconia and yttria, airgel particles also contain at least the other oxides of Tb and Bi.
    [076] The zirconia airgel can typically be characterized by at least one of the following characteristics: a. comprise crystalline particles that have an average primary particle size in a range from 2 nm to 50 nm or from about 2 nm to about 30 nm or from about 2 to about 20 or from about 2 to about 15 nm ; B. crystalline zirconia particle content: at least about 85 mol%; ç. have an organic content of at least 3% by weight or within a range of about 3 to about 10% by weight; d. dimension x, y, z: at least about 5 or at least about 8 or at least about 10 or at least about 20 mm.
    [077] A combination of characteristics (a) and (b) or (a) and (c) or (a), (b) and (c) may be preferred. and.
    [078] Heat treatment to obtain porous zirconia material is typically done under the following conditions: • temperature: from about 900 to about 1100 ° C or from about 950 to about 1090 ° C; from about 975 to about 1080 ° C; • atmosphere: air or inert gas (for example, nitrogen, argon); • duration: until a density of about 40 to about 60% of the final density of the material has been reached.
    [079] Heat treatment or calcination can be carried out in one or more steps:
    [080] In a first heat treatment stage, a binder burn could be carried out to remove all organic additives from previous steps in the process to obtain the so-called “white body”. In a second stage of heat treatment, the strength and / or hardness of the white body can be adjusted to the needs of the continuation processes, such as machining. In the case of a machinable raw block, the sintering protocol must reflect the interaction of temperature with strength and / or hardness. If the temperature is too low, the hardness and / or strength of the resulting article could be too low. This can cause problems during a later machining step, for example, with respect to chipping. If, on the other hand, the temperature is too high, the hardness and / or resistance of the material can become too high. This can cause problems during a later machining step as well, for example, regarding the durability of the machining tool. The dwell time (that is, the time that the airgel is kept at that temperature) is also useful for tuning the strength and / or hardness to the specific needs of the chosen machining technology. The residence time, however, can also be in the range of about 0 to about 24 h or about 0.1 to about 5 h. If the residence time is too long, the rough blocks for dental prosthesis machining can become very difficult to be machined under reasonable conditions.
    [081] According to one embodiment, the porous zirconia material of the rough block for machining dental prosthesis of the porous zirconia article can be obtained through a process that includes the steps of: • providing a zirconia sol comprising a solvent and crystalline particles of oxides of Zr, Y, Bi and Tb, and optionally the oxides of Er and Mn, • optionally concentrate the zirconia sol to provide a concentrated zirconia sol, • mix the sol with a polymerizable organic matrix (for example example, adding a reactive surface modifier to the zirconia sol and, optionally, an initiator that is capable of forming modified particles with the polymerizable surface of the zirconia sol); • optionally melt the zirconia sol in a mold to provide a molten zirconia sol; • cure the polymerizable organic matrix of the zirconia sol to form a gel (sometimes also called the gelling step), • remove the solvent from the gel (for example, first removing water, if present, from the gel via a solvent exchange process to provide a gel that is at least partially dehydrated; followed by another extraction step in which the remaining solvent is extracted via supercritical extraction) to obtain the airgel, • optionally cut the airgel into smaller pieces, • heat the airgel to obtain, for example, a material or machinable article.
    [082] Producing porous ceramic zirconia material according to this process can be beneficial because it allows a more homogeneous distribution of dye and fluorescent oxides in the material, compared to a process using a mixing and machining approach. In addition, the general chemical composition of the porous ceramic zirconia material can be better controlled as the raw materials used typically contain less impurities. In addition, the risk that the material is contaminated by particles resulting from the machining equipment (eg machining spheres) used is reduced. The process of producing the porous ceramic zirconia material typically begins with the supply of a sol of ZrO2 particles. In the process of making these particles, salts of fluorescence agent Bi and dyeing agents Tb and optionally Er and / or Mn can be added.
    [083] In the ZrO2 particle sol, a surface modifying agent is preferably added, a cross-linkable surface modifying agent (for example, a radically reactive surface modifier). The ZrO2 particles having been superficially modified with a crosslinkable agent can be polymerized, if desired, to provide a composition comprising crosslinked ZrO2 particles. The crosslinkable surface modifying agent can be removed later, for example, during a calcination and / or pre-sintering step.
    [084] If desired, the sun is cast in a mold. The mold can have the negative shape of the block for machining dental prosthesis to be supplied. Due to the size reduction that can be caused by heat treatments of the material, the size of the mold is typically larger than the size of the rough block for machining the final dental prosthesis. The shape of the mold is not particularly limited.
    [085] The molten zirconia sol is typically treated with heat or radiation to initiate that of the reactive surface modifier. This process usually results in a gel.
    [086] If present and desired, water can be removed from the gel, at least partially. The remaining solvent from the gel / sol process described above is removed, for example, by supercritical extraction techniques resulting in an airgel (for example, in block form). If desired, the airgel can be cut into smaller pieces, for example, having the shape of the rough block for machining dental prosthesis.
    [087] Zirconia suns are dispersions of zirconia-based ceramic particles. Zirconia in zirconia-based ceramic particles is crystalline, and it has been observed to be cubic, tetragonal, monoclinic, or a combination thereof. Because the cubic and tetragonal phases are difficult to differentiate with the use of X-ray diffraction techniques, these two phases are typically combined for quantitative purposes and are called the cubic / tetragonal phase. “Cubic / tetragonal” or “C / T” is used interchangeably to refer to the most tetragonal cubic crystalline phases. The percentage of cubic / tetragonal phase can be determined, for example, by measuring the peak area of the X-ray diffraction peaks for each phase and using equation (I). % C / T = 100 (C / T) x (C / T + M) (I) In equation (I), C / T refers to the peak area of the diffraction peak for the cubic / tetragonal phase, M refers to the peak area of the diffraction peak for the monoclinic phase, and% C / T refers to the percentage, by weight, of the cubic / tetragonal crystalline phase. The details of X-ray diffraction measurements are described more fully in the Examples section below.
    [088] Typically, at least 50 (in some embodiments, at least 55, 60, 65, 70, 75, 80, 85, 90, or at least 95) percent, by weight, of the zirconia-based particles are present in the cubic or tetragonal crystalline structure (i.e., cubic crystalline structure, tetragonal crystalline structure, or a combination thereof). A higher content of the cubic / tetragonal phase is often desired.
    [089] The zirconia particles in the zirconia suns described here are typically primary particle size in the range of 2 nm to 50 nm (in some embodiments, 5 nm to 50 nm, 2 nm to 25 nm, 5 nm to 25 nm, 2 nm to 15 nm, or even 5 nm to 15 nm). Depending on how the zirconia-based particles are prepared, the particles may contain at least some organic material in addition to inorganic oxides. For example, if the particles are prepared using a hydrothermal approach, there may be some organic material attached to the surface of the zirconia-based particles. Although there is no desire to be bound by the theory, it is believed that the organic material originates from carboxylate species (anion, acid, or both) included in the raw material or formed as a by-product of hydrolysis and condensation reactions (this ie, organic material is often adsorbed on the surface of zirconia-based particles). For example, in some embodiments, the zirconia-based particles contain up to 15 (in some embodiments, up to 12, 10, 8, or even up to 6) percent by weight of organic material, based on the weight of the particles.
    [090] Although any of a variety of known methods can be used to obtain zirconia-based particles, they are preferably prepared using hydrothermal technology. In an exemplary embodiment, zirconia-based suns are prepared by hydrothermal treatment of solutions, aqueous suspensions of metal salt (for example, a zirconium salt, a yttrium salt, and an optional lanthanide element salt or a salt of aluminum) or a combination thereof.
    [091] Aqueous metal salts, which are selected to be water-soluble, are typically dissolved in the aqueous medium. The aqueous medium can be water or a mixture of water with other water-soluble or water-miscible materials. In addition, aqueous metal salts and other water-soluble or water-miscible materials that may be present are typically selected to be removable during subsequent processing steps and to be non-corrosive.
    [092] At least most of the salts dissolved in the raw material are usually carboxylate salts instead of halide salts, oxide-halide salts, nitrate salts, or oxynitrate salts. Although there is no desire to bind to the theory, it is believed that halide and nitrate anions in the raw material tend to result in the formation of zirconia-based particles that are predominantly of a monoclinic phase rather than the most desirable tetragonal or cubic. In addition, carboxylates and / or their acids tend to be more compatible with an organic matrix material compared to halides and nitrates. Although any carboxylate anion can be used, the carboxylate anion often has no more than 4 carbon atoms (for example, formate, acetate, propionate, butyrate, or a combination thereof). Dissolved salts are often acetate salts. The raw material can additionally include, for example, the corresponding carboxylic acid of the carboxylate anion. For example, raw materials prepared from acetate salts often contain acetic acid.
    [093] An exemplary zirconium salt is the zirconium acetate salt, represented by a formula such as ZrO ((4-n) / 2CH3COO) n + (-) n, in which n is in the range of 1 to 2. The ion Zirconium can be present in a variety of structures depending, for example, on the pH of the raw material. Methods of preparing zirconium acetate are described, for example, in WB Blumenthal, “The Chemical Behavior of Zirconium", p. 311-338, D. Van Nostrand Company, Princeton, NJ, USA (1958). Suitable aqueous solutions of zirconium acetate are commercially available, for example, from Magnesium Elektron, Inc., Flemington, NJ, USA, which contains, for example, up to 17 percent by weight of zirconium, up to 18 percent by weight of zirconium, up to 20 percent by weight of zirconium, up to 22 percent by weight, up to 24 percent by weight, up to 26 percent by weight, and up to 28 percent by weight of zirconium, with based on the total weight of the solution.
    [094] Similarly, yttrium salts, lanthanide element salts, and exemplary aluminum salts often have a carboxylate anion, and are commercially available. Because these salts are typically used in much lower concentrations than the zirconium salt, salts other than carboxylate salts (eg acetate salts) can also be useful (eg nitrate salts).
    [095] The total amount of the various salts dissolved in the raw material can be readily determined based on the total percentage of solids selected for the raw material. The relative quantities of the various salts can be calculated to provide the selected composition for the zirconia-based particles. Typically, the pH of the raw material is acidic. For example, the pH is usually less than 6, less than 5, or even less than 4 (in some modalities, it is in a range of 3 to 4).
    [096] The liquid phase of the raw material is typically predominantly water (ie, the liquid phase is a water-based medium). Preferably, the water is deionized to minimize the introduction of alkali metal ions, alkaline earth metal ions, or both in the raw material. Optionally, water-miscible organic cosolvents are included in the liquid phase in amounts, for example, up to 20 percent by weight, based on the weight of the liquid phase. Suitable co-solvents include 1-methoxy-2-propanol, ethanol, isopropanol, ethylene glycol, N, N-dimethylacetamide, and N-methylpyrrolidone.
    [097] When subjected to hydrothermal treatment, the various salts dissolved in the raw material undergo hydrolysis and condensation reaction to form the zirconia-based particles. These reactions are often accompanied by the release of an acidic by-product. That is, the by-product is often one or more carboxylic acids corresponding to the zirconium carboxylate salt plus any other carboxylate salt in the raw material. For example, if the salts are acetate salts, acetic acid is formed as a by-product of the hydrothermal reaction.
    [098] Any suitable hydrothermal reactor can be used for the preparation of the zirconia-based particles. The reactor can be a batch or continuous reactor. Heating times are typically shorter and temperatures are typically higher in a continuous hydrothermal reactor compared to a batch hydrothermal reactor. The time of hydrothermal treatments can be varied depending, for example, on the type of reactor, the temperature of the reactor, and the concentration of the raw material. The pressure in the reactor can be autogenous (that is, the water vapor pressure at the reactor temperature), it can be hydraulic (that is, the pressure caused by the pumping of a fluid against a restriction), or it can result from the addition of a inert gas such as nitrogen or argon. Suitable hydrothermal batch reactors are available, for example, from Parr Instruments Co., Moline, IL, USA. Some suitable continuous hydrothermal reactors are described, for example, in US Patent Nos. 5,453,262 (Dawson and others) and 5,652,192 (Matson and others); Adschiri et al., J. Am. Ceram. Soc., 75, 1019-1022 (1992); and Dawson, Ceramic Bulletin, 67 (10), 1673-1678 (1988).
    [099] In some modalities, the raw material is passed through a continuous hydrothermal reactor. As used herein, the term “continuous” with reference to the hydrothermal reactor system means that the raw material is continuously introduced and an effluent is continuously removed from the heated zone. The introduction of raw material and the removal of effluent typically occur in locations other than the reactor. Continuous insertion and removal can be constant or pulsed.
    [0100] The dimensions of the tubular reactor can be varied and in combination with the flow rate of the raw material, they can be selected to provide adequate residence times for the reagents in the tubular reactor. Any tubular reactor of suitable length can be used as long as the residence time and temperature are sufficient to convert zirconium into the raw material into zirconia-based particles. The tubular reactor often has a length of at least 0.5 meters (in some modalities, at least 1 meter, 2 meters, 5 meters, 10 meters, 15 meters, 20 meters, 30 meters, 40 meters, or even at least 50 meters). The length of the tubular reactor in some modalities is less than 500 meters (in some modalities, less than 400 meters, 300 meters, 200 meters, 100 meters, 80 meters, 60 meters, 40 meters, or even less than 20 meters).
    [0101] Tubular reactors with a relatively small internal diameter are sometimes preferred. For example, tubular reactors having an internal diameter of no more than about 3 centimeters are often used because of the rapid rate of heating of the raw material that can be achieved with these reactors. Also, the temperature gradient across the tubular reactor is smaller for reactors with a smaller internal diameter compared to those with a larger internal diameter. The larger the inner diameter of the tubular reactor, the more this reactor resembles a batch reactor. However, if the inner diameter of the tubular reactor is very small, there is an increased possibility that the reactor will become obstructed or partially obstructed during the operation resulting from the deposition of material on the reactor walls. The inner diameter of the tubular reactor is often at least 0.1 cm (in some embodiments, at least 0.15 cm, 0.2 cm, 0.3 cm, 0.4 cm, 0.5 cm, or even at least minus 0.6 cm). In some modalities, the diameter of the tubular reactor is not greater than 3 cm (in some modalities, not greater than 2.5 cm, 2 cm, 1.5 cm, or even greater than 1 cm; in some modalities, in a range from 0.1 to 2.5 cm, 0.2 cm to 2.5 cm, 0.3 cm to 2 cm, 0.3 cm to 1.5 cm, or even 0.3 cm to 1 cm).
    [0102] In a continuous hydrothermal reactor, the temperature and residence time are typically selected together with the dimensions of the tubular reactor to convert at least 90 mol percent of zirconium into the raw material into zirconia-based particles using a single hydrothermal treatment. That is, at least 90 mol percent of the zirconium dissolved in the raw material is converted into zirconia-based particles within a single passage through the continuous hydrothermal reactor system.
    [0103] Alternatively, for example, a multi-stage hydrothermal process can be used. For example, the raw material can be subjected to a first hydrothermal treatment to form an intermediate containing zirconium and a by-product such as a carboxylic acid. A second raw material can be formed by removing at least a portion of the by-product from the first hydrothermal treatment of the zirconium-containing intermediate. The second raw material can then be subjected to a second hydrothermal treatment to form a sol containing the zirconia-based particles. Additional details about this process are described, for example, in US patent No. 7,241,437 (Davidson et al.).
    [0104] If a two-stage hydrothermal process is used, the percent conversion of the zirconium-containing intermediate is typically in the range of 40 to 75 mol percent. The conditions used in the first hydrothermal treatment can be adjusted to achieve conversion within this range. Any suitable method can be used to remove at least part of the by-product from the first hydrothermal treatment. For example, carboxylic acids, such as acetic acid, can be removed by a variety of methods such as vaporization, dialysis, ion exchange, precipitation, and filtration.
    [0105] When referring to a continuous hydrothermal reactor, the term "residence time" means the average duration of time that the raw material remains within the heated portion of the continuous hydrothermal reactor system.
    [0106] Any suitable flow of the raw material through the tubular reactor can be used as long as the residence time is long enough to convert the dissolved zirconium into zirconia-based particles. That is, the flow rate is often selected based on the residence time required to convert zirconium into the raw material into zirconia-based particles. Higher flow rates are desirable to increase speed and to minimize the deposition of materials on the walls of the tubular reactor. A higher flow rate can often be used when the reactor length is increased or when both the reactor length and diameter are increased. The flow through the tubular reactor can be laminar or turbulent.
    [0107] In some exemplary continuous hydrothermal reactors, the reactor temperature is in the range of 170 ° C to 275 ° C, 170 ° C to 250 ° C, 170 ° C to 225 ° C, 180 ° C to 225 ° C, 190 ° C to 225 ° C, 200 ° C to 225 ° C, or even 200 ° C to 220 ° C. If the temperature is higher than about 275 ° C, the pressure may be unacceptably high for some hydrothermal reactor systems. However, if the temperature is less than about 170 ° C, the conversion of zirconium in the raw material to zirconia-based particles can be less than 90 percent, by weight, using typical residence times.
    [0108] The effluent from hydrothermal treatment (ie, product from hydrothermal treatment) is a zirconia-based sol. The sol contains at least 3 percent by weight of dispersed, suspended zirconia-based particles, or a combination thereof in an aqueous medium.
    [0109] In some embodiments, zirconia-based particles may contain (a) 0 to 5 mol percent of a lanthanide element oxide, based on the total moles of inorganic oxide in the zirconia-based particles, and (b) 1 to 15 mol percent of yttrium oxide, based on the total moles of inorganic oxide in the zirconia-based particles.
    [0110] The zirconia-based particles are crystalline and have an average primary particle size of no more than 50 nanometers. In some embodiments, cerium oxide, magnesium oxide, ytterbium oxide, and / or calcium oxide can be used with or in place of yttria.
    [0111] In some embodiments, at least a portion of the water-based medium is removed from the sun based on zirconia. Any suitable medium to remove the water-based medium can be used. This water-based medium contains water and often contains carboxylic acids and / or their dissolved anions that are present in the raw material or that are by-products of the reaction that takes place inside the hydrothermal reactor. As used herein, the term "carboxylic acids and / or their anions" refers to carboxylic acids, carboxylate anions, or mixtures thereof. The removal of at least a portion of these carboxylic acids and / or their anions from the sun based on zirconia may be desirable in some modalities. The zirconia-based sol can be subjected, for example, to at least one among vaporization, drying, ion exchange, solvent exchange, diafiltration, or dialysis, for example, for concentration, removal of impurities or for compatibility with other components present In the sun.
    [0112] In some modalities, the zirconia sol (prepared by the hydrothermal process or other processes) is concentrated. Along with the removal of at least a portion of the water present in the effluent, the process of concentration or drying often results in vaporization of at least a portion of the dissolved carboxylic acids.
    [0113] In other modalities, for example, the zirconia-based sun can be subjected to dialysis or diafiltration. Both dialysis and diafiltration tend to remove at least a portion of the carboxylic acids and / or their dissolved anions. For dialysis, a sample of the effluent can be placed inside a membrane bag that is closed and then placed inside a water bath. Carboxylic acid and / or carboxylate anions diffuse out of the sample into the membrane pouch. That is, these species will diffuse out of the effluent through the membrane bag into the water bath to equalize the concentration inside the membrane bag for the concentration in the water bath. The water in the bath is typically replaced several times to lower the concentration of species in the pouch. A membrane pouch is typically selected, which allows the diffusion of carboxylic acids and / or their anions but does not allow the diffusion of zirconia-based particles out of the membrane pouch.
    [0114] For diafiltration, a permeable membrane is used to filter the sample. The zirconia particles can be retained by the filter if the pore size of the filter is properly chosen. Carboxylic acids and / or their dissolved anions pass through the filter. Any liquid that passes through the filter is replaced with fresh water. In a continuous diafiltration process, the sample is often diluted to a predetermined volume and then concentrated back to the original volume by ultrafiltration. The dilution and concentration steps are repeated one or more times until the carboxylic acids and / or their anions are removed or lowered to an acceptable concentration level. In a continuous diafiltration process, which is often called a constant volume diafiltration process, fresh water is added at the same rate as the liquid is removed through filtration. The carboxylic acids and / or their dissolved anions are in the liquid that is removed.
    [0115] Although most of the yttrium and lanthanum, if present, are incorporated into the crystalline zirconia particles, there is a fraction of these metals that can be removed during the diafiltration or dialysis process. The actual composition of a sun after diafiltration may be different from that before dialysis.
    [0116] A zirconia-based sol comprises dispersed and / or suspended zirconia-based particles (i.e., dispersed, suspended, or a combination thereof) in an aqueous / organic matrix. In some embodiments, the zirconia-based particles can be dispersed and / or suspended in the organic matrix without any additional surface modification. The organic matrix can be added directly to the sun based on zirconia. Also, for example, the organic matrix can be added in the sun based on zirconia after treatment to remove at least some of the water, after treatment to remove at least some of the carboxylic acids and / or their anions, or after both treatments. The organic matrix that is added often contains a polymerizable composition that is substantially polymerized and / or cross-linked to form a gel.
    [0117] In some embodiments, the zirconia-based sun can be subjected to a solvent exchange process. An organic solvent having a higher boiling point than water can be added to the effluent. Examples of organic solvents that are suitable for use in a solvent exchange method include 1-methoxy-2-propanol and N-methylpyrrolidone. The water can then be removed by a method such as distillation, rotary evaporation, or oven drying. Depending on the conditions used to remove the water, at least a portion of the carboxylic acid and / or its dissolved anion can also be removed. Another organic matrix material can be added to the treated effluent (that is, another organic matrix material can be added to the zirconia-based particle suspended in the organic solvent used in the solvent exchange process).
    [0118] In some embodiments, zirconia-based suns are treated with a surface modifying agent to improve compatibility with the organic matrix material. Surface modifying agents can be represented by the formula A-B, in which group A is able to bond to the surface of a zirconia-based particle and B is a compatibility group. Group A can be attached to the surface by adsorption, formation of an ionic bond, formation of a covalent bond, or a combination thereof. Group B can be reactive or non-reactive and often tends to impart characteristics to the zirconia-based particles that are compatible (that is, miscible) with an organic solvent, with other organic matrix material (for example, monomer, oligomers, or polymeric material), or both. For example, if the solvent is non-polar, group B is typically selected to also be non-polar. Suitable B groups include linear or branched hydrocarbons that are aromatic, aliphatic, or both aromatic and aliphatic. Surface modifying agents include carboxylic acids and / or their anions, sulfonic acids and / or their anions, phosphoric acids and / or their anions, phosphonic acids and / or their anions, silanes, amines, and alcohols. Suitable surface modifying agents are further described, for example, in PCT application publication No. WO 2009/085926 (Kolb et al.), The description of which is incorporated herein by reference.
    [0119] A surface modifying agent can be added to the zirconia-based particles using conventional techniques. The surface modifying agent can be added before or after removing at least a portion of the carboxylic acids and / or their anions from the sun based on zirconia. The surface modifying agent can be added before or after removing zirconia-based water from the sun. The organic matrix can be added before or after the surface modification or simultaneously with the surface modification. Various methods of adding the surface modifying agent are further described, for example, in WO 2009/085926 (Kolb et al.), The description of which is incorporated herein by reference.
    [0120] Surface modification reactions can occur at room temperature (for example, 20 ° C to 25 ° C) or at an elevated temperature (for example, up to about 95 ° C). When surface modifying agents are acids such as carboxylic acids, zirconia-based particles can typically be modified on their surface at room temperature. When the surface modifying agents are silanes, the zirconia-based particles are typically modified on their surface at elevated temperatures.
    [0121] The organic matrix typically includes a polymeric material or a precursor to a polymeric material such as a monomer or an oligomer having a polymerizable group and a solvent. The zirconia-based particles can be combined with the organic matrix using conventional techniques. For example, if the organic matrix is a precursor to a polymeric material, zirconia-based particles can be added before the polymerization reaction. Composite material containing a precursor to a polymeric material is often formatted prior to polymerization.
    [0122] Representative examples of monomers include monomers based on (meth) acrylate, monomers based on styrene, and monomers based on epoxide. Representative examples of reactive oligomers include, polyesters having (meth) acrylate groups, polyurethanes having (meth) acrylate groups, polyethers having (meth) acrylate groups, or acrylics. Representative examples of polymeric material include polyurethanes, poly (meth) acrylates, and polystyrenes.
    [0123] Zirconia-based suns are typically solidified by gelation. Preferably, the gelling process allows large gels to be formed without cracking and that gels can be further processed without crack induction. For example, preferably, the gelation process leads to a gel having a structure that will not flatten when the solvent is removed. The gel structure is compatible with and stable in a variety of solvents and conditions that may be required for supercritical extraction. In addition, the gel structure needs to be compatible with supercritical extraction fluids (for example, supercritical CO2). In other words, the gels must be sufficiently stable and strong to withstand drying, in order to produce stable gels and give materials that can be heated to burn pre-sintered, organic and densified materials without inducing cracks. Preferably, the resulting gels have a relatively small and uniform pore size to assist sintering them to high density at low sintering temperatures. However, preferably the pores of the gels are large enough to allow gaseous products of burnt organic materials to escape without causing cracking of the gel. In addition, the gelation step allows the control of the resulting gel density to assist the subsequent processing of the gel such as supercritical extraction, burning of organic compounds, and sintering. It is preferred that the gel contains the minimum amount of organic material or polymer modifiers.
    [0124] The gels described here contain zirconia-based particles. In some embodiments, gels contain at least two types of zirconia-based particles varying in crystalline phases, composition, or particle size. We have found that particulate gels can cause less contraction compared to gels made from alkoxides that experience significant and complicated condensation and crystallization reactions during further processing. The crystalline nature allows combinations of different crystalline phases at a nanoscale. Applicants have observed that the formation of a gel by polymerizing these reactive particles gives strong, resilient gels. Applicants have also found that the use of mixtures of suns with crystalline particles can allow for the formation of stronger and more resilient gels for further processing. For example, applicants have observed that a gel comprising a mixture of cubic and tetragonal zirconia particles was less susceptible to cracking during the stages of supercritical extraction and burning of organic material.
    [0125] The gels comprise organic material and crystalline metal oxide particles, in which the crystalline metal oxide particles are present in a range of 3 to 20 percent volume, based on the total volume of the gel, where at least 70 (in some modalities, at least 75, 80, 85, 90, 95, 96, 97, 98, or even at least 99; in a range of 70 to 99, 75 to 99, 80 to 99, or even 85 to 99 ) mol percent of the crystalline metal oxide is ZrO2. Optionally, the gels can also include sources of amorphous non-crystalline oxide.
    [0126] In some embodiments, the gels described here, crystalline metallic oxide particles have an average primary particle size in the range of 5 nanometers to 50 nanometers (in some embodiments, in the range of 5 nanometers to 25 nanometers, 5 nanometers to 15 nanometers, or even 5 nanometers to 10 nanometers). Typically, the average primary particle size is measured using the X-ray diffraction technique. Preferably, the particles are not agglomerated, but it is possible that particles with some degree of aggregation may also be useful.
    [0127] Exemplary sources of ZrO2, Y2O3 and Al2O3 include crystalline zirconia-based sols prepared by any suitable means. The suns described above are particularly well suited. Y2O3 and Al2O3 can be present in zirconia-based particles, and / or present as separate colloidal particles or soluble salts.
    [0128] In some embodiments, for the gels described here, the crystalline metallic oxide particles comprise a first plurality of particles, and a second different plurality of particles (that is, it is distinguishable by medium composition, phase (s), microstructure, and / or size).
    [0129] Typically, the gels described here have an organic content that is at least 3 (in some embodiments, at least 4, 5, 10, 15, or even at least 20) percent by weight, based on the total weight of the gel. In some embodiments, the gels described here have an organic content in a range of 3 to 30, 10 to 30, or even 10 to 20, percent by weight, based on the total weight of the gel.
    [0130] Optionally, the gels described herein comprise at least one of Y2O3 (for example, in which a range of 1 to 15, 1 to 9, 1 to 5, 6 to 9, 3.5 to 4.5, or even 7 to 8 mole percent of the crystalline metal oxide is Y2O3), La2O3 (for example, up to 0.5 mole percent of La2O3), or Al2O3 (for example, up to 0.5 mole percent of Al2O3).
    [0131] In an exemplary gel, the crystalline metallic oxide comprises a range of 1 to 5 mol percent of Y2O3 and a range of 0 to 2 mol percent of La2O3 and a range of 93 to 97 mol percent of ZrO2. In another exemplary gel, the crystalline metallic oxide comprises in a range of 6 to 9 mol percent of Y2O3, and in a range of 0 to 2 mol percent of La2O3 and in a range of 89 to 94 mol percent of ZrO2. In another example gel, the crystalline metallic oxide comprises a range of 3.5 to 4.5 mol percent of Y2O3 and a range of 0 to 2 mol percent of La2O3 and a range of 93.5 to 96.5 mol per percent of ZrO2. In another example gel, the crystalline metallic oxide comprises a range of 7 to 8 mol percent of Y2O3 and in a range of 0 to 2 mol percent of La2O3 and a range of 90 to 93 mol percent of ZrO2. In some embodiments, the amount of optional oxide (s) (optional) is an amount ranging from about 10 ppm to 20,000 ppm. In some embodiments, it is desirable to have sufficient oxides present so that the crack-free crystalline metallic oxide articles are tooth-colored.
    [0132] An exemplary method for making gels described herein comprises providing a first zirconia sol comprising crystalline metal oxide particles having an average primary particle size no larger than 15 nanometers (in some embodiments, in a range of 5 nanometers to 15 nanometers) nanometers), in which at least 70 (in some modalities, at least 75, 80, 85, 90, 95, 96, 97, 98, or even at least 99; in a range of 70 to 99, 75 to 99, 80 to 99, or even 85 to 99) mol percent of the crystalline metal oxide is ZrO2. The sun is optionally concentrated to provide a concentrated zirconia sun.
    [0133] A co-solvent, surface modifiers and optional monomers are added under agitation to obtain a well-dispersed sun. Also, a radical initiator (for example, thermal initiator or ultraviolet (UV) initiator) is added to the radically polymerized superficially modified zirconia sol.
    [0134] The resulting sol is optionally purged with N2 gas to remove oxygen. The resulting sol can be gelled by actinic radiation or by heating to at least one temperature for a time sufficient to polymerize the modified zirconia sol with a radically polymerizable surface comprising the radical initiator to form a gel. Typically the resulting gel is a strong, translucent gel. In some embodiments, the suns for preparing the airgel described herein comprise zirconia-based particles that have their surface modified with a radically polymerizable surface treatment modifier / agent.
    [0135] Exemplary radically polymerizable surface modifiers include acrylic acid, methacrylic acid, beta-carboxyethyl acrylate, and mono-2- (methacryloxyethyl) succinate. An exemplifying modifying agent to impart both polar character and reactivity to nanoparticles containing zirconia is mono succinate (methacryloxypoliethylene glycol). Exemplary polymerizable surface modifiers can be reaction products of polymerizable monomers containing hydroxyl with cyclic anhydrides such as succinic anhydride, maleic anhydride and phthalic anhydride. Exemplary hydroxyl-containing polymerizable monomers include hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, hydroxybutyl acrylate, and hydroxybutyl methacrylate. Acyloxy-functional and methacryloxy-functional poly (ethylene oxide), and acyloxy-functional and methacryloxy-functional poly (propylene oxide) can also be used as the polymerizable monomers containing hydroxyl. Exemplifying polymerizable silanes include alkyltrialoxyalkylsilanes, methacryloxyalkyltrialcoxysilanes or acryloxyalkyltrialcoxysilanes (for example, 3-methacryloxypropyltrimethoxysilane, 3-acryloxypropyltrimethoxysilane (3-methacryloxy) propylmethyl; methacryloxyalkylalkylalkoxysilanes or acryloxyalkylalkylalkoxysilanes (for example, 3 - (methacryloxy) - propyldimethylethoxysilane); mercaptoalkyltrialkoxysilanes (for example, 3-mercaptopropyltrimethoxysilane); aryltrialcoxysilanes (for example, styylethyltrimethoxysilane); vinylsilanes (for example, vinylmethyldiethoxysilane, vinylldimethylethoxysilane, vinylmethyldiethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltriacethoxysilane, vinyltriisopropoxysilane, vinyltrimethoxysilane and vinyltris (2-methoxyethoxy) ssilane).
    [0136] Methods for adding a surface modifying agent to nanoparticles containing zirconia are known in the art. The surface modifying agent can be added, for example, before or after any removal of at least a portion of the carboxylic acids and / or their anions from the sun containing zirconia. The surface modifying agent can be added, for example, before or after removing sun water containing zirconia. The organic matrix can be added, for example, after the surface modification or at the same time as the surface modification.
    [0137] In an exemplifying embodiment, the gel is formed by radical polymerization of the modified particles on its surface and optional monomers. Polymerization can be initiated by any suitable means such as thermal initiators, actinic radiation, UV initiators. Exemplary thermal initiators include (2,2'-azobis (2-methylbutyronitrile) (available, for example, under the trade name “VAZO 67” from EI du Pont de Nemours & Co., Wilmington, DE, USA), azobisisobutyronitrile ( available, for example, under the trade name “Vazo 64” from EI du Pont de Nemours & Co.), 2,2'-azodi- (2,4-dimethylvaleronitrile (available, for example, under the trade name “Vazo 52 ”from EI du Pont de Nemours & Co.), and 1,1'-azobis (cyclohexanecarbonitrile) (available, for example, under the trade name“ Vazo 88 ”from EI du Pont de Nemours & Co. Peroxides and hydroperoxides (eg benzoyl peroxide and lauryl peroxide) can also be useful. Initiator selection can be influenced, for example, by the choice of solvent, solubility and desired polymerization temperature. 2,2'- azobis (2-methylbutyronitrile) available from EI du Pont de Nemours & Co. under the designation c “VAZO 67”).
    [0138] Exemplary UV initiators include 1-hydroxy-cyclohexyl-benzophenone (available, for example, under the trade name “IRGACURE 184” from Ciba Specialty Chemicals Corp., Tarrytown, NY, USA), 4- (2-hydroxyethoxy) phenyl- (2-hydroxy-2-propyl) ketone (available, for example, under the trade name “IRGACURE 2529” from Ciba Specialty Chemicals Corp.), 2-hydroxy-2-methylpropiophenone (available, for example, under the trade name “DAROCURE D111” from Ciba Specialty Chemicals Corp. and bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide (available, for example, under the trade name “IRGACURE 819” from Ciba Specialty Chemicals Corp.) .
    [0139] Liquid or solvent in the gel can be exchanged with a second liquid, for example, by soaking the gel in the second liquid for a time sufficient to allow an exchange to occur. For example, water present in a gel can be removed by soaking the gel in a dry solvent (for example, dry ethanol).
    [0140] Aerogels described here are formed by removing solvent from the zirconia gels described here without excessive shrinkage (for example, not greater than about 10%). The gel structure must be strong enough to withstand at least some shrinkage and cracking during drying (solvent removal).
    [0141] Aerogels can be prepared by drying gels via supercritical extraction. In some embodiments, aerogels are prepared by drying gels under supercritical conditions of the solvent used in the preparation of the gel.
    [0142] In some airgel types described here, crystalline metallic oxide particles have an average primary particle size in the range of 2 nm to 50 nm (in some embodiments, 5 nm to 50 nm, 2 nm to 25 nm, 5 nm to 25 nm, 2 nm to 15 nm, or even 5 nm to 15 nm).
    [0143] Typically, the airgel described here has an organic content that is at least 3 (in some embodiments, at least 4, 5, 10, 15, or even at least 20) percent by weight, based on the total weight of the airgel. In some embodiments, the airgel described here has an organic content in a range of 3 to 30, 10 to 30, or even 10 to 20 percent, by weight, based on the total weight of the airgel.
    [0144] Optionally, the airgel described here comprises at least one of Y2O3 (for example, in a range of 1 to 15, 1 to 9, 1 to 5, 6 to 9, 3.5 to 4.5, or even 7 to 8 mol percent of the crystalline metal oxide is Y2O3), AI2O3, (for example, up to 0.5 mol percent of Al2O3). An exemplary airgel comprises in a range of 1 to 5 mol percent of the crystalline metallic oxide is Y2O3, and in a range of 0 to 2 mol percent of the crystalline metallic oxide is La2O3 and in a range of 93 to 99 mol percent of the crystalline metallic oxide is ZrO2. Another exemplary airgel comprises in a range of 6 to 9 mol percent of the crystalline metallic oxide is Y2O3 and in a range of 0 to 2 mol percent of the crystalline metallic oxide is La2O3 and in a range of 89 to 94 mol percent of the oxide crystalline metallic is ZrO2. In another exemplary airgel the crystalline metallic oxide comprises in a range of 3.5 to 4.5 mol percent of Y2O3 and in a range of 0 to 2 mol percent of the crystalline metallic oxide is La2O3 and in a range of 93.5 to 96.5 mol percent ZrO2. In another exemplary airgel the crystalline metallic oxide comprises in a range of 7 to 8 mol percent of Y2O3, and in a range of 0 to 2 mol percent of the crystalline metallic oxide is La2O3 and in a range of 90 to 93 mol percent of ZrO2. In some embodiments, it is desirable to have sufficient oxides present so that the crack-free crystalline metallic oxide articles are tooth-colored.
    [0145] The airgel described here typically has a percentage by volume of oxide in a range of 3 to 20 (in some embodiments, 3 to 15, 3 to 14, or even 8 to 14) percent. Airgel with lower volume percentages of oxide tends to be very fragile and crack during supercritical drying or subsequent processing. Airgel with higher oxide content tends to crack when burning organic material because it is more difficult for volatile by-products to escape the denser structure.
    [0146] In some modalities, airgel described here has a surface area in the range of 100 m2 / g to 300 m2 / g (in some modalities, 150 m2 / g to 250 m2 / g) and a continuous pore channel size in a range from 10 nm to 20 nm. In some embodiments, the airgel structure described herein is a composite of oxide particles, 3 nm to 10 nm (in some embodiments 4 nm to 8 nm) in size and organics composed of acetate groups and polymerized monomers. The amount of organic material is typically 10 to 20 weight percent of the airgel.
    [0147] Aerogels described herein can be made, for example, by providing a first zirconia sol comprising crystalline metallic oxide particles having an average primary particle size of up to 50 nm (in some embodiments, 2 nm to 50 nm, 5 nm at 25 nm, 2 nm at 15 nm, or even 5 nm at 15 nm), where at least 70 (in some embodiments, at least 75, 80, 85, 90, 95, 96, 97, 98, or even at minus 99; in a range of 70 to 99, 75 to 99, 80 to 99, or even 85 to 99) mol percent of the crystalline metal oxide is ZrO2. The first zirconia sol is then optionally concentrated to obtain a concentrated zirconia sol. A co-solvent, surface modifiers and optional monomers are added while stirring to obtain a well-dispersed sun, where the co-solvent is optional).
    [0148] A radical initiator (eg, ultraviolet (UV) initiator or thermal initiator) is added to the modified zirconia sol with radically polymerizable surface. Optionally, the resulting sol is purged with N2 gas to remove oxygen. The resulting sol is then gelled by radiation with actinic radiation or by heating to at least one temperature and for a time sufficient to polymerize the modified zirconia sol with a radically polymerizable surface comprising the radical initiator to form a gel. Typically the resulting gel is a strong, translucent gel. The water, if present, is then removed from the gel via exchange for alcohol to obtain a gel that is at least partially drained. The gel is then converted to an airgel by removing the alcohol, if present, from the partially drained gel via supercritical extraction to obtain the airgel.
    [0149] In an exemplary embodiment, removing the first liquid solvent from the at least partially drained gel comprises replacing the first liquid solvent with a second liquid solvent, then slowly increasing the temperature and pressure of the at least partially drained gels until they are obtained supercritical conditions for the second solvent, then slowly release the pressure to about 100 kPa (1 bar) to obtain the monolithic airgel.
    [0150] In some embodiments, the complete exchange of the first liquid solvent with the second solvent is carried out under supercritical conditions. In some embodiments, the first liquid solvent is miscible with the second solvent. This method comprises placing at least partially dehydrated gel in a pressure vessel with sufficient volume of the first liquid solvent to fully immerse the gel, pumping the second solvent into the autoclave at a temperature above the critical temperature of the second solvent until a pressure greater than the critical pressure of the second solvent is reached, maintain the supercritical pressure in the pressure vessel long enough to complete the solvent exchange by pumping an additional amount of the second solvent into the pressure vessel while simultaneously bleeding the mixture of the first and second solvents to a separating vessel, then slowly releasing the pressure to 100 kPa (1 bar) to supply the monolithic airgel. Typically, the second solvent is carbon dioxide.
    [0151] The invention also relates to a kit of parts comprising the rough block for machining dental prosthesis described in this text and one of the following components: - instructions for use, - fastening means or devices for reversibly fixing or connecting the raw machining block to a machining device, or combinations thereof.
    [0152] The instructions for use typically contain information on machining processes and parameters to be applied and also sintering conditions useful for sintering the machined article to final density.
    [0153] The process of producing the zirconia ceramic dental article comprises the steps of a) providing the rough block for machining dental prosthesis comprising the porous zirconia material, b) placing the rough block for machining dental prosthesis in a device machining, c) machining the porous zirconia material to obtain a machined porous zirconia ceramic dental article.
    [0154] The machining step is typically being done with or using a rolling or grinding device. These devices are commercially available with, for example, 3M ESPE (LAVA ™ Form) or Sirona (CEREC ™ inLab CAD / CAM). The machining step can be done with a machining, drilling, cutting, sculpting or grinding device.
    [0155] Useful rolling parameters include: - rolling speed of the rolling tool: 5,000 to 40,000 revolutions / min; - feed rate: 20 to 5,000 mm / min; - lamination cutter diameter: 0.8 to 4 mm.
    [0156] The process of producing the dental zirconia article can also comprise the step of sintering the article obtained by machining the raw block for machining porous zirconia dental prosthesis.
    [0157] Sintering will result in a zirconia dental article, sometimes also called a crystalline metallic oxide article.
    [0158] If performed, the firing or sintering step must be performed under conditions that result in an acceptable dental ceramic article having a tooth-like color (for example, a color that fits the Vita ™ shade guide.
    [0159] Useful sintering conditions can be characterized by one or more of the following parameters: - temperature: from about 900 to about 1500 ° C or from 1000 to about 1400 ° C or from about 1100 ° C to about 1350 ° C or about 1200 ° C to about 1400 ° C or about 1300 ° C to about 1400 ° C or about 1320 ° C to about 1400 ° C or about 1340 ° At about 1350 ° C. - atmosphere: air or inert gas (for example, nitrogen, argon); - duration: until a density of about 95 or about 98 or about 99 to about 100% of the final density of the material has been reached. - residence time: from about 1 to about 24 h or from about 2 to about 12 h; - pressure: ambient pressure.
    [0160] One oven that can be used is the Lava ™ Therm (3M ESPE) available for sale.
    [0161] During the firing process, the porous dental article is sintered to its final shape, thus being subjected to changes regarding size, density, hardness, flexural strength and / or grain size.
    [0162] The residence time (that is, the time that the article is kept at that temperature) is not really critical. The residence time can be zero. The residence time, however, can also be in the range of about 0 to about 24 hours or about 0.1 to about 5 hours.
    [0163] The firing temperature and dwell time (that is, the length of time during which a specific temperature is maintained) are typically correlated. A higher temperature typically requires only a short residence time. Thus, the residence time can last from about 0 (for example, if the firing temperature is about 1,550 ° C) to about 10 h (for example, if the firing temperature is about 1,100 ° C) or from about 0.1 to about 8 h.
    [0164] In general, the sintering or firing conditions are adjusted in such a way that the sintered dental ceramic article has a density equal to or greater than about 98% compared to the theoretically obtainable density.
    [0165] The invention is also directed to the dental article obtainable or obtained by the process described in the present text. The ceramic dental article can be in the shape of a crown, bridge, inner layer, top layer, veneer, veneer, transfer, crown and bridge structure, implant, support, orthodontic appliances (for example, brackets, mouth tubes, braces and buttons) and parts of it. The rough block for machining dental prostheses described in this text can be used to produce monolithic dental restorations.
    [0166] The ceramic dental article after a sintering step can normally be characterized by one or more of the features presented below: • density: fully sintered at least about 98.5 (in some modes 99, 99.5, 99 , 9 or even at least 99.99) percent theoretical density • Vickers hardness: from about 450 MPa to about 2200 MPa, or from about 500 MPa to about 1800 MPa.HV (2); • Tetragonal phase of the phase content: from about 1 to about 100%, by weight, or from about 10 to about 100%, by weight; cubic phase: from about 30 to about 100% by weight, or from about 50 to about 90% by weight; • Biaxial flexural strength: from about 450 MPa to about 2200 MPa, or from about 500 MPa to about 2000 MPa.
    [0167] A preferred modality of the rough block for machining dental prosthesis described in this text can be characterized as follows:
    [0168] A rough block for machining dental prosthesis having the shape of a block or disk, the rough block for machining dental prosthesis comprising a porous zirconia material and means for connecting it to a machining device, • being that the porous zirconia material comprises • Zr oxide calculated as ZrO2: from about 80 to about 97% by weight, • Al oxide calculated as Al2O3: from about 0 to about 0.15% by weight , • Y oxide calculated as Y2O3; from about 1 to about 10% by weight • Bi oxide calculated as Bi2O3: from about 0.01 to about 0.20% by weight • Tb oxide calculated as Tb2O3: from about 0 , 01 to about 0.8% by weight, and optionally one or two of the following oxides: • Er oxide calculated as Er2O3: from about 0.01 to about 3.0% by weight, • oxide of Er Mn calculated as MnO2: from about 0.0001 to about 0.01% by weight,% by weight, with respect to the weight of the porous zirconia material, the porous zirconia material does not comprise • a glass, glass ceramics or lithium disilicate and • Fe oxide calculated as Fe2O3 in an amount of more than about 0.01% by weight or more than about 0.005% by weight or more than about 0.001 % by weight, and the porous zirconia material is characterized by the following parameters: • show an adsorption and desorption isotherm of N2 with a hysteresis loop of type H1 according to the IUPAC classification, especially in a range of p / p0 from 0.70 to 0.95; • BET surface: from about 10 to about 200 m2 / g; • Resistance to biaxial flexion: from about 10 to about 40 MPa; • dimension x, y, z: at least about 5 mm; • Density: about 30 to about 95% of theoretical density; • Shrinkage: isotropic.
    [0169] All components used in the dental composition of the invention must be sufficiently biocompatible, that is, the composition must not produce a toxic, harmful or immunological response in living tissue.
    [0170] The dental article described in this text does not typically contain components or additives that impair the intended purpose to be achieved with the invention. Thus, components or additives added in an amount that ultimately results in a non-tooth-colored dental article are not normally contained in the dental article. Typically, an article is characterized as not being tooth color if it cannot be assigned a color using the Vita ™ color coding system, known to the person skilled in the art. In addition, components that will reduce the mechanical strength of the dental restoration to a degree, where mechanical failure will occur, are also not normally included in the dental article.
    [0171] The zirconia ceramic dental article does not contain glass, glass ceramic materials, lithium disilicate ceramic materials or combinations thereof.
    [0172] The production of the zirconia material described in this text does not typically also require the application of a hot isostatic pressure (HIP) step.
    [0173] The complete description of the patents, patent documents and publications cited in the present disclosure are hereby incorporated, in their entirety, by way of reference as if each were individually incorporated. Various modifications and alterations in the context of this invention will become evident to those skilled in the art, without departing from the character and scope of this invention. The specification, examples and data above provide a description of the manufacture and use of the compositions and methods of the invention. The invention is not limited to the modalities presented in the present invention. The person skilled in the art will appreciate that many alternative modalities of the invention can be carried out without deviating from the character and scope of the invention.
    [0174] The following examples are given to illustrate, but not limit, the scope of this invention. All parts and percentages are by weight, unless otherwise indicated. EXAMPLES
    [0175] Except where otherwise noted, all parts and percentages are weight based, all water is deionized water and all molecular weights are weight average molecular weights. In addition, except where otherwise indicated, all experiments were conducted under ambient conditions (23 ° C; 101.3 kPa (1013 mbar). Measurements Ion concentration
    [0176] If desired, the ion concentration can be determined by X-ray fluorescence spectrometry (XRF). Some XRF devices offer the possibility to directly measure ion concentrations in liquid solutions, for example, ZSX Primus II from Rigaku, Japan. Fluorescence
    [0177] The fluorescence properties can be determined using an optical configuration comprising the following parts (particularly suitable for sharp emission bands): Gas chromatograph America G-Light as a light source, irradiation light of about 409 nm wavelength, an Ulbricht sphere, optical fiber from Topsensor Systems as a light conductor and an A / D converter. A sample that is disk-shaped (diameter> 10 mm, thickness 1.0 mm) can be used to cover the opening of the Ulbricht sphere. The light emission spectrum of the sample can be measured during trans-illumination with excitation radiation (violet light). Excitation radiation of shorter wavelengths is also suitable for fluorescence measurements.
    [0178] Another option is to measure the remission spectrum of the samples, for example, with a spectrophotometer (for example, Color i7; X-Rite). Normally, two measurements are made: a remission spectrum with the use of irradiation, for example, from the D65 light source that includes the UV range and a remission spectrum with irradiation, for example, from the D65 light source excluding the range of UV. Subsequently, both spectra are subtracted from each other, where the production curve shows the effect (s) of fluorescence. The area between 410 nm and 540 nm is defined as the area of fluorescence, while the area between 550 nm and 710 nm is defined as the background. The signal strength of the background area is subtracted from the signal strength of the fluorescence area to obtain the relative fluorescence intensity.
    [0179] Choosing this measurement method may be preferable, because it also produces color information about the sample (that is, L * a * b * values).
    [0180] Alternatively, samples can be placed in a UV light box used for inspection of, for example, thin layer chromatography plates. If desired, fluorescence can be detected by the human eye as well as by illuminating the sample against the black background. Average Grain Size
    [0181] If desired, the average grain size can be determined with the Line Intercept Analysis. FESEM micrographs at 70,000 times magnification are used to measure grain size. Three or four micrographs taken from different areas of the sintered body are used for each sample. The horizontal lines, which are spaced at approximately equal intervals across the height of each micrograph, are drawn. The numbers of grain contour intercepts observed on each line are counted and used to calculate the average distance between the intercepts. The average distance for each line is multiplied by 1.56 to determine the grain size and this value is measured against all lines for all micrographs of each sample. Density
    [0182] If desired, the density of the sintered material can be measured by an Archimedes technique. Measurements are made on a precision scale (identified as “AE 160” from Mettler Instrument Corp., Hightstown, NJ, USA) using a Density Determination Kit (identified as “ME 33360” from Mettler Instrument Corp .). In this procedure, the sample is first weighed in air (A), then immersed in water (B). The water is distilled and deionized. A drop of a wetting agent (obtained under the trade name “TERGITOL-TMN-6” from Dow Chemical Co., Danbury, CT, USA) is added to 250 ml of water. The density is calculated using the formula p = (A / (A-B)) p0, where p0 is the water density. The relative density can be calculated with reference to the theoretical density (pt) of the material, prel = (p / pt) 100. Vickers Hardness
    [0183] If desired, Vickers hardness can be determined according to ISO 843-4 with the following modifications: The sample surface is ground using silicon carbide grinding paper (P400 and P1200). The test forces are adjusted up to the hardness level of the samples. Test forces used were between 0.2 kg and 2 kg and were applied for 15 s each indentation. A minimum of 10 indentations are measured to determine the average Vickers hardness. The tests can be carried out with a Leco M-400-G hardness tester (Leco Instrumente GmbH). Resistance to biaxial flexion
    [0184] If desired, the biaxial flexural strength can be determined according to ISO 6872 (2008) with the following modifications: The sample is sawn in 1 to 2 mm thick inserts using a dry cutting saw . The diameter of the samples must be between 12 and 20 mm. Each insert is centered on a support of three steel balls with a support diameter of 14 mm. The puncture diameter in contact with the insert is 3.6 mm. The puncture is pushed into the insert at a rate of 0.1 mm per minute. A minimum of 6 samples are measured to determine the average strength. The tests can be conducted on an Instron 5566 universal testing machine (Instron Deutschland GmbH). Example of Invention 1:
    [0185] A composition of sol containing Zr oxide (92.3% by weight; calculated as ZrO2), Y oxide calculated as Y2O3 (7.10% by weight), Er oxide calculated as Er2O3 (0, 41%, by weight), Tb oxide calculated as Tb2O3 (0.11%, by weight), Bi oxide calculated as Bi2O3 (0.066%, by weight), Mn oxide calculated as MnO2 (0.00038%, in weight) was prepared with a hot tube reactor using the respective metal acetates.
    [0186] The sun was concentrated and the water was partially replaced by a TFF process. The concentrated sol was solidified by mixing 60.57 g sol, 2.88 g acrylic acid, 1.475 g N-hydroxyethyl acrylamide, 1.88 g ethanol, Vazo initiator, filling the mixture in PP syringes and curing at 50 ° C for 4 hours.
    [0187] The gels were removed from the syringes and immersed in pure ethanol to exchange the water for ethanol in the gels. The gels were then supercritically extracted with CO2. After that, the gels were de-agglutinated and pre-sintered. After slicing the cylindrical blocks into disks, they were sintered to full density. A more detailed description of the process can be found, for example, in US patent 2013/055432 (3M). The resulting zirconia material showed a color similar to B3 or B4 on the Vita ™ Classical scale and is fluorescent under UV light. Invention Example 2
    [0188] To achieve a calculated composition of 99.109% by weight of Zr oxide (calculated as ZrO2), 0.574% by weight of Er oxide (calculated as Er2O3), 0.250% by weight of oxide of Zr Tb (calculated as Tb4O7), 0.066% by weight of Bi oxide (calculated as Bi2O3) and 0.00081% by weight of Mn oxide (calculated as MnO2), bonded ZrO2 powder (TZP), mixture ZrO2 / Er2O3 powder (2.18%, by weight, Er2O3 powder), Tb4O7 powder, Bi2O3 powder, and ZrO2 / MnO2 powder mixture (0.035%, by weight, MnO2 powder) were mixed by intense agitation and then pressed into cylindrical blocks applying a pressure of 200 MPa. The blocks were de-agglomerated, pre-sintered, sliced into discs and then sintered to full density.
    [0189] The resulting zirconia material showed a similar color to B3 on the Vita ™ Classical scale and is fluorescent under UV light. Comparative example 1:
    [0190] To achieve a calculated composition of 99.466% by weight of Zr oxide (calculated as ZrO2), 0.346% by weight of Er oxide (calculated as Er2O3), 0.028% by weight of oxide of Zr Fe (calculated as Fe2O3), 0.159% by weight of Bi oxide (calculated as Bi2O3) and 0.00120% by weight of Mn oxide (calculated as MnO2), agglutinated ZrO2 powder (TZP), mixture ZrO2 / Er2O3 powder (11.435% by weight of Er2O3 powder oxide), ZrO2 / Fe2O3 powder mixture (1.435% by weight of Fe2O3 powder), ZrO2 / Bi2O3 powder mixture (0.224 % by weight of Bi2O3 powder) and ZrO2 / MnO2 powder mixture (0.33% by weight of MnO2 powder) were mixed by intense stirring and then pressed into cylindrical blocks. The blocks were de-agglomerated, pre-sintered, sliced into discs and then sintered to full density.
    [0191] The resulting zirconia material showed a similar color to B3 on the Vita ™ Classical scale and is only weakly fluorescent under UV light. In comparison to the Example of Invention 2, the tooth color is brighter, but the fluorescence is less. Results / Findings
    [0192] The iron-based zirconia material and bismuth doping in an amount as in the comparative example above was not sufficiently fluorescent for dental applications when the iron concentration was at the level of an A1 tooth color on the Vita ™ scale Classical or above (for example, A3, B3). In comparison to this, the shade of terbium and doping of bismuth can produce darker tones (for example, tooth color B3 on the Vita ™ Classical scale) while maintaining a high degree of fluorescence.
    权利要求:
    Claims (8)
    [0001]
    1. Crude block for dental prosthesis machining, CHARACTERIZED by the fact that it has a shape that allows the rough block for dental prosthesis machining to be connected or fixed to a machining device, the rough block for dental prosthesis machining comprising a material porous zirconia, the porous zirconia material comprising the oxides of Zr calculated as ZrO2: from about 80 to about 97% by weight, Al oxide calculated as Al2O3: from 0 to about 0.15% by weight, Y oxide calculated as Y2O3: from 1 to about 10% by weight, Bi oxide calculated as Bi2O3: from 0.01 to about 0.20% by weight, Tb oxide calculated as Tb2O3: from 0.01 to about 0.8% by weight, the porous zirconia material not comprising Fe oxide calculated as Fe2O3 in an amount of more than about 0.01% by weight,% by weight with respect to the weight of the porous zirconia material.
    [0002]
    2. Crude block for machining dental prosthesis, according to claim 1, CHARACTERIZED by the fact that the porous zirconia material is defined by at least one or all of the following parameters: show an adsorption isotherm and nitrogen desorption with loop hysteresis; show an H1 type hysteresis circuit according to the IUPAC classification; show an adsorption and desorption isotherm of N2 with a hysteresis loop in a p / p0 range of 0.70 to 0.95; average connected pore diameter: from about 10 to about 100 nm; average grain size: less than about 100 nm; BET surface: from about 10 to about 200 m2 / g; resistance to biaxial flexion: from about 10 to about 40 MPa; dimension x, y, z: at least about 5 mm; Vickers hardness: from about 25 to about 150; density: about 30 to about 95% of theoretical density.
    [0003]
    3. Crude block for machining dental prostheses, according to claim 1 or 2, CHARACTERIZED by the fact that it is shaped like a disk or a block.
    [0004]
    4. Crude block for machining dental prostheses, according to any one of claims 1 to 3, CHARACTERIZED by the fact that it does not comprise at least one or all of the following components: Fe oxide calculated as Fe2O3 in an amount of more than about of 0.005% by weight, Cr oxide calculated as Cr2O3 in an amount of more than about 0.01% by weight, Cu oxide calculated as CuO in an amount of more than about 0.01% by weight, oxide of Cr V calculated as V2O5 in an amount of more than about 0.01% by weight, Mo oxide calculated as Mo2O3 in an amount of more than about 0.01% by weight, Pr oxide calculated as Pr2O3 in an amount of more than about 0.01% by weight,% by weight, with respect to the weight of the porous zirconia material.
    [0005]
    5. Crude block for machining dental prosthesis, according to claim 1, CHARACTERIZED by the fact that it does not comprise at least one or all of the following components: glass, glass ceramic, lithium disilicate ceramic, or combinations or mixtures of themselves.
    [0006]
    6. Crude block for machining dental prosthesis, according to claim 1, CHARACTERIZED by the fact that it comprises means or retention devices to connect it reversibly to a machining device, the means being selected from groove (s) , notch (s), structure (s), recess (s), punch (s), frame (s), tip (s) and combinations thereof.
    [0007]
    7. Crude block for machining dental prosthesis, according to claim 1, CHARACTERIZED by the fact that it has the shape of a block or disk, the crude block for machining dental prosthesis comprising a porous zirconia material and a connector to connect the same to a machining device, the porous zirconia material comprising: a glass, glass ceramic or lithium silicate material the porous zirconia material being defined by the following parameters: show an adsorption and desorption isotherm with N2 type H1 hysteresis, according to the IUPAC classification in a p / p0 range of 0.70 to 0.95; BET surface: from about 10 to about 200 m2 / g; resistance to biaxial flexion: from about 10 to about 40 MPa; dimension x, y, z: at least about 5 mm; density: about 30 to about 95% of theoretical density, where the connector comprises groove (s), recess (s), structure (s), notch (s), tip (s) or combinations thereof.
    [0008]
    8. Crude block for machining dental prosthesis, according to claim 1, CHARACTERIZED by the fact that it also comprises one or two of the following oxides: Er oxide calculated as Er2O3: from about 0.01 to about 3.0 % by weight, and Mn oxide calculated as MnO2: from about 0.0001 to about 0.08% by weight.
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    法律状态:
    2020-04-28| B06U| Preliminary requirement: requests with searches performed by other patent offices: procedure suspended [chapter 6.21 patent gazette]|
    2021-02-09| B09A| Decision: intention to grant [chapter 9.1 patent gazette]|
    2021-04-13| B16A| Patent or certificate of addition of invention granted|Free format text: PRAZO DE VALIDADE: 20 (VINTE) ANOS CONTADOS A PARTIR DE 03/12/2014, OBSERVADAS AS CONDICOES LEGAIS. |
    优先权:
    申请号 | 申请日 | 专利标题
    EP13195607|2013-12-04|
    EP13195607.0|2013-12-04|
    PCT/US2014/068317|WO2015084931A1|2013-12-04|2014-12-03|Dental mill blank, process for production and use thereof|
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