Glazing composition, sintering process and kit of parts for dental zirconia articles - Patent Application 20070122997

Abstract

The present invention relates to a glazing composition suitable for glazing the surface of a dental zirconia article. The glazing composition comprises a liquid, glass particles, and hydrophilic silica nanoparticles. The present invention also relates to a method for sintering a porous dental zirconia article with the glazing composition on its surface.

Description

[Technical Field]

[0001] The present invention relates to a glazing composition suitable for glazing the surface of a dental zirconia article, the glazing composition comprising a liquid, glass particles, and hydrophilic silica nanoparticles.

[0002] The present invention also relates to a method for sintering a porous dental zirconia article with a glazing composition on its surface. [Background technology]

[0003] Currently, dental restorations are typically manufactured by using one of the following approaches:

[0004] One approach is to use open-pore oxide ceramics that can be machined in the office or chairside.

[0005] However, after the milling process, a time-consuming heat treatment process is required to obtain a high-strength material, during which, for example, a glass material is infiltrated into the porous ceramic article to improve the article's strength.

[0006] Such methods are described, for example, in U.S. Patent Application Publication No. 2012 / 0064490(A1) (Rothbrust et al.). Infiltration of the pores of the open-pore oxide ceramic with an infiltrant is typically carried out in a vacuum to a depth of 2-90% of the thickness of the open-pore oxide ceramic. Infiltration depths in the range of 0.2-0.8 mm have been reported.

[0007] Another approach is to mill fully sintered zirconia.

[0008] The strength level of fully sintered zirconia is high compared to that of glass-ceramic materials. However, aesthetics may not be considered entirely satisfactory, and grinding itself is time-consuming. Furthermore, a glazing or polishing step is typically required to achieve the desired aesthetic gloss.

[0009] Such an approach is described, for example, in U.S. Patent Application Publication No. 2017 / 143456(A1) (Carden et al.), in which a fully sintered zirconia material is ground into a dental restoration in a chairside grinder.

[0010] Another approach is to use a pre-sintered zirconia material.

[0011] Zirconia dental restorations are made in a dental laboratory by machining a pre-sintered (porous) block into the desired shape, thereby accounting for shrinkage of the zirconia material during the subsequent firing process.

[0012] If after the firing step a particularly shiny, highly aesthetic dental restoration is desired, a second so-called glaze firing step is typically required.

[0013] Furthermore, glazing of zirconia restorations is often recommended to reduce the risk of wear on the opposing teeth and for aesthetic reasons.

[0014] In this regard, glass powder is manually applied to the surface of the sintered zirconia material, and both are fired at temperatures much lower than the sintering temperature of the porous zirconia material. The glass powder typically melts at temperatures below 900°C.

[0015] WO 2016 / 142234(A1) (Gebr.Brasseler) describes a mixture of substances for finishing zirconium dioxide dental restorations, which contains a so-called superflammable lithium silicate system and / or a feldspar system dispersed in an organic liquid. The heat treatment is typically carried out at temperatures of 850-950°C. The zirconium dioxide surface is described as preferably pore-free.

[0016] U.S. Patent Application Publication No. 2008 / 0241551(A1) (Zhang et al.) suggests a method for preparing a functionally graded glass / zirconia / glass sandwich material, comprising the steps of: a) applying certain powdered glass-ceramic compositions to accessible surfaces of a pre-sintered zirconia substrate; b) infiltrating the substrate with the glass-ceramic composition; and c) densifying the substrate by heating. The Examples section describes the glass-ceramic powder compositions used to infiltrate pre-sintered bodies of yttria-stabilized zirconia.

[0017] When such methods are applied to porous dental zirconia materials, the resulting articles do not meet the requirements of aesthetic dental restorations. Summary of the Invention

[0018] A problem observed in applying commercially available glazing compositions to the surface of dental zirconia articles is that the glazing compositions are sometimes difficult to handle, especially when the surface of the dental zirconia article is porous.

[0019] Thus, there is a need for improved glazing compositions, particularly glazing compositions that can be used to glaze porous dental zirconia articles.

[0020] The glazing composition and porous dental zirconia articles treated with the glazing composition should be easy to handle.

[0021] In addition, use of the glazing composition should ideally result in an aesthetic dental zirconia restoration.

[0022] It is also desirable to have a glazing composition in close proximity that can be co-fired with the porous dental zirconia article to which it is applied.

[0023] One or more of these objectives will be addressed by the present invention as described and claimed herein.

[0024] In one embodiment, the invention features a glazing composition for dental zirconia restorations, as described herein and claimed in the claims. The glazing composition includes a liquid, glass particles, and hydrophilic silica nanoparticles.

[0025] A further embodiment of the present invention is directed to a method of making a dental zirconia restoration as described and claimed herein, comprising the steps of providing a porous dental zirconia article, applying a glazing composition described herein to at least a portion of a surface of the porous dental zirconia restoration, and sintering the porous dental zirconia article with the glazing composition on its surface to final density.

[0026] A further embodiment of the present invention is directed to a dental restoration obtainable or obtainable by this method.

[0027] The present invention also relates to a kit-of-parts as described herein and claimed herein, comprising a glazing composition as described herein and claimed herein, a dental zirconia mill blank suitable for producing a dental restoration, and optionally the following items, alone or in combination: a sintering aid, an application tool for a surface treatment, a shade guide, a grinding aid, and a sintering oven.

[0028] The invention further features the use of hydrophilic silica nanoparticles as a binder to produce the glazing compositions described and claimed herein.

[0029] Unless otherwise defined, as used herein, the following terms have the meanings set forth below.

[0030] The term "dental article" refers to any article used in the field of dentistry, in particular dental restorations, and to the manufacture of these parts.

[0031] Dental articles typically have three-dimensional inner and outer surfaces, including convex and concave structures. Compared to other articles, such as porcelain or paving stones, dental articles are small and delicate. The thickness of dental articles can vary from very thin areas, such as the edges and rims (less than 0.1 mm), to much thicker areas, such as the occlusal region (up to 8 mm). The section bridging the crown portion in a dental bridge can have a thickness of up to 20 mm.

[0032] The outer surface typically has a generally convex shape, while the inner surface typically has a generally concave shape.

[0033] Typically, the dental articles described herein, after sintering, comprise or consist essentially of a polycrystalline ceramic material comprising yttrium-stabilized ZrO2.

[0034] Examples of dental articles include crowns (such as monolithic crowns), bridges, inlays, onlays, veneers, facings, copings, crown and bridge frameworks, implants, abutments, orthodontic appliances (e.g., brackets, buccal tubes, cleats, and buttons), monolithic dental restorations (i.e., restorations that do not require veneer bonding), and portions thereof.

[0035] Tooth surfaces are not considered dental articles.

[0036] Dental articles should not contain ingredients that are harmful to the patient's health and therefore are free of harmful and toxic ingredients that may migrate from the dental article.

[0037] "Dental mill blank" means a solid block of material (a three-dimensional article) from which a dental article, dental workpiece, dental supporting structure, or dental restoration can be, and typically is, machined by any subtractive method, such as milling, as well as grinding, drilling, etc.

[0038] A dental mill blank has a geometrically defined shape and at least one flat surface. So-called "free-form surfaces" are not considered "geometrically defined." In this regard, the shape of a dental restoration (e.g., a crown or bridge) itself is not considered a dental mill blank.

[0039] "Zirconia article" shall mean a three-dimensional article having at least one of the x, y, z dimensions of at least about 5 mm, the article being composed of at least 80% by weight, or at least 90% by weight, or at least 95% by weight, zirconia.

[0040] "Ceramic" means an inorganic, non-metallic material produced by the application of heat. Ceramics are typically hard, porous, and brittle and, in contrast to glasses or glass-ceramics, exhibit an essentially pure crystalline structure.

[0041] "Crystalline" means a solid composed of atoms arranged in a three-dimensional periodic pattern (i.e., having a long-range crystalline structure as determined by X-ray diffraction). Crystalline structures include tetragonal, monoclinic, and cubic zirconia, and mixtures thereof.

[0042] "Monolithic dental restoration" means a dental ceramic article that does not have a facing or veneer applied to its surface. That is, a monolithic dental restoration is essentially composed of only one material composition. However, a thin glazing layer may be applied if desired.

[0043] "Glass" refers to an inorganic, non-metallic, amorphous material that is thermodynamically supercooled to a liquid. Glass refers to a hard, brittle, transparent solid. Typical examples include soda-lime glass and borosilicate glass. Glass is the inorganic product of a fusion that has been cooled to a rigid state without crystallizing. Most glasses contain silica as their primary component and certain amounts of intermediate and modifier oxides, such as glass-forming ingredients.

[0044] The porous ceramic dental materials described herein are glass-free.

[0045] "Glass-ceramic" refers to an inorganic, non-metallic material in which one or more crystalline phases are surrounded by a glass phase, such that the material contains a combination or mixture of glass and ceramic materials. It is formed as a glass and then crystallized by a nucleation and crystallization heat treatment. Glass-ceramics can refer, for example, to mixtures of lithium oxide, silicon oxide, and aluminum oxide.

[0046] The porous dental materials described herein do not contain glass-ceramics.

[0047] The "Littleton softening point" of glass is the temperature at which the glass reaches 10 7.6 P (poise) (or 10 6.6 Pa * s), which is the lower boundary of the operating range in which the glass can change shape.

[0048] The "pour point" is the temperature at which the glass 5 P or 10 4 Pa* The viscosity of the glass is the temperature at which it reaches a viscosity of 1000 psi. This is the temperature at which the glass begins to flow, which can be activated by squeezing, foaming, or pulling. If desired, this viscosity can be measured with a rotating plate viscometer.

[0049] "Powder" means a dry bulk consisting of many fine particles that can flow freely when shaken or tilted.

[0050] "Particle" means a solid substance having a geometrically measurable shape. The shape can be regular or irregular. Particles can typically be analyzed, for example, with respect to particle size and particle size distribution.

[0051] "Density" refers to the ratio of mass to volume of an object. Density is typically measured in g / cm 3 The density of an object can be calculated, for example, by determining its volume (e.g., by calculation or by applying Archimedes' principle or method) and measuring its mass.

[0052] The volume of the sample can be determined based on the overall external dimensions of the sample. The density of the sample can be calculated from the measured sample volume and sample mass. The total volume of the ceramic material can be calculated from the sample mass and the density of the material used. The total volume of the bubbles in the sample is assumed to be the remainder of the sample volume (100% minus the total volume of the material).

[0053] "Porous material," in the ceramic arts, refers to a material that contains partial volumes formed by voids or pores.

[0054] Thus, an "open-celled" structure of a material is sometimes referred to as an "open-porous" structure, and a "closed-celled" material's structure is sometimes referred to as a "closed-pored" structure. Materials with an open-cell or open-porous structure can, for example, allow gas to pass through.

[0055] "Average connected pore diameter" refers to the average size of the open-cell pores of a material. Average connected pore diameter can be calculated as described in the Examples section.

[0056] The term "calcination" refers to the process of heating a solid material to remove at least 90 weight percent of volatile chemically bound components (e.g., organic components) (e.g., as opposed to a drying process in which physically bound water is removed by heating). Calcination is carried out at a temperature lower than that required to carry out a pre-sintering step.

[0057] The terms "sintering" and "firing" are used interchangeably. The porous ceramic article shrinks during the sintering process, i.e., when a suitable temperature is applied. The sintering temperature applied varies depending on the ceramic material selected. For ZrO2-based ceramics, a typical sintering temperature range is 1,100°C to 1,550°C. Higher temperatures may be required if sintering is performed at a high heating rate. Sintering typically involves densifying a porous material into a less porous material (or a material with fewer voids) with a higher density, and in some cases may involve a change in the material phase composition (e.g., partial conversion from an amorphous phase to a crystalline phase).

[0058] A dental zirconia article is classified as "pre-sintered" when the dental zirconia article has been treated with heat (in the temperature range of 900-1,100°C) for 1 to 3 hours to such an extent that the green fracture resistance of the dental ceramic in the "three ball punch test" is in the range of 15-55 MPa or 20-50 MPa, as measured in accordance with ISO 6872:2015.

[0059] Pre-sintered dental ceramics typically have a porous structure and their density (typically about 3.0 g / cm for yttrium-stabilized ZrO ceramics) 3 ) is used for fully sintered dental ceramic frameworks (typically about 6.1 g / cm for yttrium-stabilized ZrO2 ceramics). 3 ) is lower than

[0060] "Machining" means milling, grinding, cutting, carving, or shaping a material with a machine. Milling is usually faster and more cost-effective than grinding. A "machinable article" is an article that has a three-dimensional shape and is strong enough to be machined.

[0061] The term "capable of being combusted without leaving any residue" means that when about 200 mg of the component is heated to a temperature of about 750°C for about 1 minute at ambient pressure, no visible deposit (visible to the human eye) can be found.

[0062] That is, the components may be vaporized or burned to produce only gaseous components including carbon monoxide and water.

[0063] This can be determined, if desired, by visually (using only the human eye) inspecting the final dental restoration obtained after the firing step. The grayish appearance of the dental restoration can be an indicator of a dental composition that does not meet the above-mentioned characteristics. For example, the use of a composition containing a compound with a long carbon chain (e.g., a polymer with a carbon backbone) typically results in a dental restoration with a grayish appearance, which is undesirable.

[0064] "Ambient conditions" refers to the conditions to which the solution of the present invention is normally exposed during storage and handling. Ambient conditions may be, for example, a pressure of 900-1100 mbar, a temperature of 10-40°C, and a relative humidity of 10-100%. In the laboratory, ambient conditions are adjusted to 20-25°C and 1000-1025 mbar.

[0065] If a composition does not contain a particular component as an essential feature, the composition is "essentially or substantially free" of the component. Therefore, the component is not intentionally added to the composition, either alone or in combination with other components or ingredients of other components. A composition that is essentially free of a particular component usually does not contain that component at all. However, sometimes, the presence of a small amount of this component cannot be avoided, for example, due to impurities contained in the raw materials used.

[0066] As used herein, "a," "an," "the," "at least one," and "one or more" are used interchangeably. Also herein, the recitations of numerical ranges by endpoints include all numbers subsumed within that range (e.g., 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, 5, etc.).

[0067] The terms "comprise" or "contain" and variations thereof do not have a limiting meaning where these terms appear in the specification and claims. The term "comprise" is also intended to include the terms "consist essentially of" and "consists of."

[0068] Adding "(s)" to a term means that the term is to include the singular and the plural. For example, the term "additive(s)" means one additive as well as two or more additives (e.g., two, three, four, etc.).

[0069] Unless otherwise indicated, all numbers used in the specification and claims expressing quantities of ingredients, measurements of physical properties, e.g., those set forth below, are to be understood as being modified in all instances by the term "about."

[0070] "And / or" means either one or both. For example, expression component A and / or component B refers to component A only, component B only, or both component A and component B. DETAILED DESCRIPTION OF THE INVENTION

[0071] The glazing compositions described herein have been found to have several advantageous properties.

[0072] When glass particles are used to glaze porous dental zirconia articles, the fired glass has a slight white haze or the surface finish is not as smooth as desired.

[0073] Undesirable haze can be caused by chemical separation effects during firing or by the incorporation of air bubbles into the glaze layer.

[0074] Furthermore, the surface finish can sometimes appear dull, especially if the melting temperature of the glass in the glazing composition is too high or if the surface prepared during application of the glazing composition is too rough.

[0075] The present invention shows that the risk of these problems occurring can be reduced by using or adding hydrophilic nano-sized silica particles to the formulation of the glazing composition.

[0076] Without being bound to any particular theory, it is believed that the hydrophilic nano-sized silica particles help to obtain better packing of the glaze particles during application, thus reducing the risk of possible air inclusions.

[0077] It may also be possible that the nano-sized silica particles act as a lubricant between the glass particles contained in the glazing composition during firing, ensuring a suitable surface finish.

[0078] It has been observed that the nano-sized silica particles help to bond or secure the glass particles to the surface of the porous dental zirconia article, even when the liquid used to disperse the glass particles in the glazing composition is absorbed by the porous dental zirconia article to which the glazing composition is applied.

[0079] As a result, the treated outer surface of the porous dental zirconia article can be handled more easily, reducing the risk of accidentally removing the applied layer of glass particles, which improves robustness during handling prior to firing.

[0080] Surprisingly, it has also been observed that the presence of nano-sized silica particles does not adversely affect the aesthetics of the glaze, even when the melting temperature range of the silica particles does not perfectly match the melting temperature range of the glass of the glazing composition.

[0081] For certain embodiments, it has been observed that the aesthetics of the glaze can be further improved when nano-sized silica particles are added to the glazing composition, particularly with respect to gloss and haze.

[0082] Thus, it has been discovered that the addition or use of hydrophilic nano-sized silica particles can favorably affect the properties of dental glazing compositions.

[0083] The addition or use of hydrophilic nano-sized silica particles is particularly useful in producing glazing compositions that can be used during the so-called "single-step firing process," i.e., a process in which the porous dental zirconia article is sintered with the glazing composition on its surface.

[0084] The glazing compositions described herein are suitable for glazing dental zirconia restorations.

[0085] The glazing composition is a liquid.

[0086] The liquid is used to disperse or dissolve the ingredients contained in the glazing composition and may be used to adjust the viscosity and consistency of the composition according to the needs of the practitioner.

[0087] characteristics The nature of the liquid is not particularly limited, provided the desired results are not unachievable.

[0088] The liquid is typically a polar liquid, which is a liquid that is miscible with water.

[0089] Typically, suitable liquids have the following characteristics: Molecular weight (Mw): 18 to 1,000 g / mol, or 40 to 400 g / mol, Boiling point: 50~300℃, Viscosity: 1~2,000mPa * s, or 1 to 1,500 mPa * s(shear rate 50s -1 (measured at 23°C), does not contain polymerizable groups such as (meth)acrylate groups, epoxy groups, or carbon-carbon unsaturated groups; does not contain an element selected from S and P; can be characterized by at least one of:

[0090] The liquid should have a boiling point that allows it to evaporate without complications during the fast firing process or during a drying step that is optionally performed before the firing process begins.

[0091] The boiling point of the liquid should not be too high, otherwise the evaporation of the liquid during the firing process may not be fast enough, and the evaporation of the liquid should be completed before the glass material begins to melt and flow.

[0092] The boiling point of the liquid may also be adjusted by using a liquid with an appropriate molecular weight.

[0093] It is beneficial for the viscosity of the liquid to be such that the glass powder can be easily dispersed.

[0094] The liquid should not contain any components or chemical elements that may cause damage to the sintering furnace used in the fast firing process.

[0095] It may be preferable to use a liquid that does not contain halogen components (eg, F, Cl, Br).

[0096] Solvents that can be used include water or polyalcohols including ethylene glycol, polyethylene glycol, glycerol, and mixtures thereof.

[0097] The polyethylene glycols that can be used can be represented by the formula: R 1 O-(CH2-CH2-O) m -R 1 In the formula, R 1 is H, acyl, alkyl, aryl, alkylaryl, polypropyl glycol, polyTHF, preferably H, acetyl, methyl, ethyl, propyl, butyl, hexyl, octyl, nonyl, decyl, lauryl, tridecyl, myristyl, palmityl, stearyl, oleyl, allyl, phenyl, p-alkylphenyl, polypropylene glycol, polyTHF, and m is 2-20, preferably 2-15, and more preferably 2-8.

[0098] The average molecular weight (Mw) of the polyethylene glycol must be in the range of 100-1,000, preferably in the range of 100-700, and more preferably in the range of 100-400.

[0099] If desired, the average molecular weight (Mw) can be determined according to procedures known to those skilled in the art, for example as described in Arndt / Muller, Polymercharakterisierung, Hanse Verlag, 1996.

[0100] Most PEGs (polyethylene glycols) contain molecules with a molecular weight distribution, i.e., they are polydisperse. The size distribution can be statistically characterized by its weight-average molecular weight (Mw) and its number-average molecular weight (Mn), the ratio of which is called the polydispersity index (Mw / Mn). Mw and Mn can be measured by mass spectrometry.

[0101] Specific examples of water-miscible liquids that can be used include polyols (including polyvinyl alcohol), glycol ethers (e.g., diethylene glycol methyl ether, diethylene glycol ethyl ether), alcohols (1,2-propanediol, 1,3-propanediol, ethanol, (n- and iso-)propanol, glycerol), glycerol ethers, and mixtures thereof.

[0102] Specific examples of polyethylene glycols that can be used include PEG 200, PEG 285-315, PEG 380-420, PEG 570-630, PEG 950-1050.

[0103] In particular, water, glycerol, ethylene glycol, propylene glycol, and mixtures thereof have been found to be useful.

[0104] The water may be distilled, deionized, or plain tap water. Typically, deionized water is used.

[0105] According to one embodiment, the solvent is water. According to another embodiment, the solvent is different from water.

[0106] The liquid is typically in the following amounts: Lower limit amount: at least 50% by weight, or at least 60% by weight; Upper limit: 95% by weight or 90% by weight Range: 50% to 95% by weight, or 60% to 90% by weight, The weight percentages are based on the total weight of the composition.

[0107] The glazing compositions described herein include glass particles.

[0108] The nature and composition of the glass particles are not particularly limited, as long as the desired purpose is not rendered unachievable.

[0109] Suitable glass has the following characteristics: a) Viscosity: at least 10 in the temperature range of 1,300°C 4 Pa * s, b) Thermal expansion coefficient: 1×10 -6 K -1 ~10×10 -6 K -1 , or 2.5 × 10 -6 K -1 ~9×10 -6 K -1 , c) Surface tension: 210mN / m to 300mN / m at 1,300℃; d) Littleton softening point viscosity at temperatures between 1,100°C and 1,350°C; e) Pour point viscosity at temperatures between 1,300°C and 1,650°C; f) Particle size: 1μm~40μm(D 50 ), These can be explained by the above alone or in combination.

[0110] The following combinations of features may be preferred: a) and b), a) and c), a) and d), a) and f), a) and e), a), b) and c), a), b) and d), a), b) and e), a), b), d) and f).

[0111] The glass typically has a sufficiently high viscosity at the sintering temperature of the porous zirconia dental article so that the glass does not migrate into the pores of the porous zirconia dental article to a greater extent than desired. Viscosity ranges in the above ranges have been found to be useful.

[0112] It can be beneficial if the value of the thermal expansion coefficient of the glass is less than that of the zirconia material, which can help increase the compressive strength of the final dental restoration and facilitate providing a durable dental restoration.

[0113] The particle size of the glass particles should not be too large as this may adversely affect the melting behavior during the sintering process.

[0114] The use of smaller glass particles typically allows for a more homogeneous melting of the glass during the sintering process.

[0115] Ideally, the particle size of the glass powder is in a range that allows for homogeneous fusion of the glass powder during the sintering process of the porous zirconia dental article.

[0116] D 50 The particle size is typically in the range of 1 μm to 40 μm, or 2 μm to 30 μm. The particle size is typically in the range of 0.1 μm to 50 μm, or 0.25 μm to 40 μm.

[0117] If desired, particle size and viscosity can be measured or obtained as described in the Examples section.

[0118] The glass is typically a silica-based glass, and the SiO2 content of the glass is typically greater than 80% by weight, preferably in the range of 80% to 98% by weight.

[0119] According to one embodiment, the glass has the following composition: [Table 1] It is characterized by having either:

[0120] The amount is expressed as mole percent relative to the glass composition.

[0121] Glass typically consists of the following components: LiO in an amount greater than 0.1 mol %; F in an amount greater than 0.1 mol %; does not contain more than 0.1 mole percent of P2O5, alone or in combination.

[0122] The presence of these components can adversely affect properties such as the melting temperature, surface tension, or viscosity of the glass.

[0123] The glass particles are typically present in the following amounts: Lower limit amount: at least 5% by weight, or at least 8% by weight; Upper limit: maximum 50% by weight, or maximum 40% by weight, Range: 5% to 50% by weight, or 8% to 40% by weight, The weight percentages are based on the total weight of the composition.

[0124] The glazing compositions described herein include hydrophilic silica nanoparticles.

[0125] The nature of the hydrophilic silica nanoparticles is not particularly limited, as long as the desired purpose is not unattainable.

[0126] The addition of hydrophilic silica nanoparticles to the glazing composition has been found to help improve handling properties during and after application.

[0127] Without being bound by any particular theory, it is believed that the hydrophilic silica nanoparticles act as a binder or lubricant for the glass particles that are applied to the surface of the treated porous dental zirconia article.

[0128] Furthermore, when the liquid components of the glazing composition are absorbed by the porous dental zirconia article, the remaining solid components, particularly the glass particles, remain well-anchored to the surface of the porous dental zirconia article.

[0129] This effect can be observed when hydrophilic silica nanoparticles are used, but not when hydrophobic silica nanoparticles are used, which are typically surface treated, e.g., silane treated.

[0130] The hydrophilic silica nanoparticles are typically non-silane treated, ie, have a surface that has not been treated with a silanizing agent.

[0131] If desired, the hydrophilic silica nanoparticles may have the following characteristics: a) BET surface: 20m 2 / g~500m 2 / g, b) Particle size (D 50 ): 10 nm to 70 nm, either alone or in combination.

[0132] Suitable hydrophilic silica nanoparticles include pyrogenic or precipitated silica or silica dispersions.

[0133] Non-silane treated silica nanoparticles that can be used are also commercially available, such as Aerosil™ OX 50, Aerosil™ 200, Aerosil™ 380, Sipernat™ 160 (Evonik), and Levasil™ 50 / 50 (Akzo Nobel).

[0134] The hydrophilic silica nanoparticles are typically present in the following amounts: Lower limit amount: at least 0.1% by weight, or at least 0.2% by weight; Upper limit: maximum 5% by weight, or maximum 4% by weight, present in the range: 0.1% to 5% by weight, or 0.2% to 4% by weight; The weight percentages are based on the total weight of the composition.

[0135] In addition to the hydrophilic silica nanoparticles, the glazing composition can also contain hydrophobic silica nanoparticles.

[0136] Hydrophobic silica nanoparticles are typically silanized. These types of particles are often used as reinforcing fillers in silicone elastomers.

[0137] If present, the amount of hydrophobic silica nanoparticles should be adjusted so as not to negate the effect obtained from the non-silane treated silica nanoparticles.

[0138] Thus, when present, hydrophobic silica nanoparticles are typically present in a lesser amount compared to the hydrophilic silica nanoparticles (e.g., less than 50% by weight, or less than 40% by weight, or less than 30% by weight, or less than 20% by weight of the amount of hydrophilic silica nanoparticles).

[0139] Silane-treated silica nanoparticles that can be used are also commercially available, examples of which include HDK™ H2000, HDK™ 1303VP, HDK™ H3004, HDK™ H15, HDK™ H20, and HDK™ H30 (Wacker).

[0140] To distinguish between hydrophilic and hydrophobic silica nano-sized particles, the following test can be performed:

[0141] A small amount of water (eg, 1 ml) is added to a small amount of silica nanoparticles (eg, 0.5 g).

[0142] Silica nanoparticles are considered hydrophilic if they are easily wetted by water. Hydrophobic particles typically do not mix with water and will remain as a separate phase.

[0143] The weight ratio of glass powder to liquid in the glazing composition typically ranges from 1:1 to 1:15, or from 1:2 to 1:12.

[0144] The ratio of hydrophilic silica nanoparticles to glass particles is typically in the range of 1:40 to 1:5 or 1:30 to 1:10 by weight.

[0145] Such a ratio has been found to be advantageous.

[0146] The ratio of glass powder to liquid can be useful for adjusting the coating properties of the glazing composition.

[0147] The ratio of hydrophilic silica nanoparticles to glass particles can be used to adjust handling properties.

[0148] The glazing compositions described herein may also further comprise a rheological additive.

[0149] The addition of rheological additives can be advantageous as they can further improve the storage stability of the glazing composition and help prevent settling or separation.

[0150] Rheological additives can also help suspend solid particles (eg, glass particles) in the glazing composition.

[0151] The rheological additive is selected so that it can burn without leaving residue during the firing process.

[0152] Rheological additives that can be used or added include starch, methyl cellulose, ethyl cellulose, hydroxyl propyl cellulose, carboxymethyl cellulose, xanthan, and mixtures thereof.

[0153] Xanthan gum is a polysaccharide. It can be produced by a process involving the fermentation of glucose or sucrose using the bacterium Xanthomonas campestris. The backbone of the polysaccharide chain contains β-D-glucose units linked through the 1- and 4-positions. The side chains contain mannose and glucuronic acid. The entire chain consists of repeating modules of five sugar units. The molecular weight of xanthan typically ranges from 1 to 50 million, depending on the method by which it is prepared.

[0154] It has been found that by adding xanthan gum to a liquid, an increase in its viscosity can be observed, even when only small amounts are added, for example on the order of 1% by weight.

[0155] Methylcellulose is a methyl ether of cellulose, resulting from the replacement of some of the hydrogen atoms of the hydroxyl groups -OH of cellulose with methyl groups -CH3, forming -OCH3 groups.

[0156] Hydroxypropyl cellulose is an ether of cellulose in which some of the hydroxyl groups in the repeating glucose units are hydroxy-propylated to form -OCH2CH(OH)CH3 groups.

[0157] When present, rheological additives are typically present in the following amounts: Lower limit amount: at least 0.1% by weight, or at least 0.2% by weight; Upper limit: maximum 1% by weight, or maximum 0.8% by weight, present in a range of 0.1% to 1% by weight, or 0.2% to 0.8% by weight; The weight percentages are based on the total weight of the composition.

[0158] The glazing compositions described herein may also further comprise a colorant.

[0159] The addition of a coloring agent can be beneficial to enhance the visibility of the glazing composition during use, especially if the composition is clear or the same color as the zirconia restoration.

[0160] Thus, the practitioner can easily determine which portions of the surface of the dental article have already had the composition applied and which portions have not yet been treated and / or should remain untreated. The colorant, which is typically organic in nature, burns off during the subsequent sintering step and is therefore not incorporated into the dental article.

[0161] Examples of soluble colorants that can be used include Riboflavin (E101), Ponceau 4R (E124), Green S (E142), and Patent Blue V (E131).

[0162] When present, colorants are typically present in the following amounts: Lower limit amount: at least 0.001% by weight, or at least 0.01% by weight; Upper limit: maximum 0.5% by weight, or maximum 0.2% by weight, present in a range of 0.001% to 0.5% by weight, or 0.01% to 0.2% by weight; The weight percentages are based on the total weight of the composition.

[0163] The glazing composition is typically provided to the practitioner in a form that allows for simple application of the glazing composition to the surface of the porous dental zirconia article.

[0164] 5mPa * s~5,000mPa * s(23℃) or 10mPa * s~3,000mPa * Viscosities of the glazing composition in the range of 1000 psi (23°C) have been found to be useful.

[0165] If the viscosity is too high or too low, it will be more difficult to apply the glazing composition accurately and precisely, the thickness of the glazing layer may be either too thick or too thin, or the liquid of the composition will be absorbed too quickly or too slowly into the porous zirconia.

[0166] The pH value of the glazing composition is typically in the range of 6-9.

[0167] If desired, the pH value of the glazing composition can be determined by using moist pH-sensitive paper to which a small portion of the glazing composition is applied.

[0168] That is, the glazing composition is typically in the neutral or slightly basic range, based on the glass particles used. It typically does not contain acidic components.

[0169] The glazing composition contains the following amounts of each component: Liquid: 50% to 95% by weight, Glass particles: 4% to 50% by weight, Hydrophilic silica nanoparticles: 0.1% to 5% by weight, The weight percentages are based on the weight of the total composition.

[0170] The glazing composition also comprises the following amounts of each component: Liquid: 60% to 90% by weight, Glass particles: 8% to 40% by weight, Hydrophilic silica nanoparticles: 0.2% to 4% by weight, The weight percentages are based on the weight of the total composition.

[0171] The glazing compositions described herein typically do not contain ingredients that are harmful to the objectives being achieved.

[0172] Because the glazing composition is intended to be used to co-fire with the porous dental zirconia article, the glazing composition typically does not contain components such as glasses that have a low melting temperature range.

[0173] These glasses begin to melt before the pores of the dental zirconia article close and, therefore, before they diffuse into the surface area of ​​the dental zirconia article where they are sintered to an undesirable extent.

[0174] Thus, according to certain embodiments, the glazing compositions described herein typically comprise the following components: glass particles having a Littleton softening point viscosity at a temperature of 1,100°C or less in an amount greater than 1% by weight; 10% by weight at 1,300°C 3 Pa * The composition does not contain glass particles having a viscosity of less than 1000 psi, alone or in combination.

[0175] According to one embodiment, a suitable glazing composition comprises the following components: a liquid selected from water, alcohol, and mixtures thereof in an amount of 60% to 95% by weight; Glass particles in an amount of 4 to 40 wt. %; The glass particles have an average particle size of 1 μm to 30 μm, The glass of this glass particle is heated to 1,300°C for 10 4 Pa * s~10 7 Pa * glass particles having a viscosity of s; Hydrophilic silica nanoparticles in an amount of 0.1 to 5 wt. %; and the weight percentages are based on the weight of the total glazing composition.

[0176] According to a further embodiment, a suitable glazing composition comprises the following components: a liquid selected from water, alcohol, and mixtures thereof in an amount of 70% to 90% by weight; Glass particles in an amount of 9 to 30% by weight, The glass particles have an average particle size of 1 μm to 20 μm, The glass of this glass particle is heated to 1,300°C for 10 4 Pa * s~10 7 Pa * glass particles having a viscosity of s; and hydrophilic silane-untreated silica nanoparticles in an amount of 0.1 to 5 wt. %. and the weight percentages are based on the weight of the total glazing composition.

[0177] According to a further embodiment, a suitable glazing composition comprises the following components: a liquid selected from water, alcohol, and mixtures thereof in an amount of 60% to 90% by weight; Glass particles in an amount of 9 to 40% by weight, The glass particles have an average particle size of 1 μm to 20 μm, The glass of this glass particle is heated to 1,300°C for 10 4 Pa * s~10 7 Pa * s viscosity, The glass is a silica-based glass; Hydrophilic silica nanoparticles in an amount of 0.1 to 5 wt. %; and the weight percentages are based on the weight of the total glazing composition.

[0178] According to a further embodiment, a suitable glazing composition comprises the following components: a liquid selected from water, alcohol, and mixtures thereof in an amount of 60% to 95% by weight; Glass particles in an amount of 4 to 40 wt. %; The glass particles have an average particle size of 1 μm to 20 μm, The glass of this glass particle is heated to 1,300°C for 10 4 Pa * s~10 7 Pa * s viscosity, Hydrophilic silica nanoparticles in an amount of 0.1 to 5 wt. %; wherein the weight percent is based on the weight of the total glazing composition; The glass has the following composition: [Table 2] wherein the amount is expressed as mole % based on the glass composition.

[0179] The glazing compositions described herein can be obtained by mixing the respective components. If desired, mixing can be carried out by using a high speed mixing device or blender.

[0180] The glazing compositions described herein are typically provided to the practitioner in a suitable receptacle, such as a liquid vessel, bottle, tube, or flask.

[0181] The glazing compositions described herein can be provided as a dispersion, a paste, or a spray.

[0182] The present invention also relates to a method for producing a dental zirconia restoration by sintering a porous dental zirconia article.

[0183] Sintered porous dental zirconia articles are typically made as follows.

[0184] A porous dental mill blank is provided that is machined to obtain a porous zirconia dental article.

[0185] The machining step can be performed by milling, drilling, cutting, carving, or grinding equipment.

[0186] These devices are commercially available, for example, from Roland (DWX Mill) or Sirona (CEREC™ inLab CAD / CAM).

[0187] If the machining is done by milling, useful milling parameters include: Milling tool rotation speed: 5,000~40,000 rpm, Feed rate: 20 to 5,000 mm / min, and / or Milling cutter diameter: 0.8 to 4 mm.

[0188] If desired, the machined porous dental zirconia restoration is cleaned to remove any grinding dust, for example, using pressurized air.

[0189] When a porous dental zirconia mill blank is used to manufacture a porous dental zirconia article, the material of the porous dental zirconia mill blank is the same as the material of the porous dental zirconia article.

[0190] Porous dental zirconia mill blanks typically have the shape of a block or disk.

[0191] When the porous zirconia dental mill blank has the shape of a block, the porous zirconia dental mill blank typically has the following dimensions: x dimension: 12~45mm or 15~40mm, y dimension: 12 to 70 mm, or 15 to 60 mm, z dimension: 10 to 30 mm or 15 to 25 mm.

[0192] When the porous dental zirconia mill blank has the shape of a disk, the porous dental zirconia mill blank typically has the following dimensions: x, y dimensions: 90~110mm or 95~105mm, z dimension: 5 to 35 mm or 10 to 30 mm.

[0193] The attachment or fastening of the dental zirconia mill blank to the machining equipment, in particular to the clamping fixtures of such equipment, may also be achieved by providing the blank with suitable means for this purpose.

[0194] Suitable means include a frame, a notch, a protrusion, a mandrel, and combinations thereof.

[0195] In another embodiment, the dental zirconia mill blank is secured to or contained within a holding device, which can then serve as a means for mounting the blank to a machining device.

[0196] The fixation of the dental zirconia mill blank to the holding device can be affected by clamping, gluing, screwing, and combinations thereof.

[0197] Useful retention devices include frames (openable) or protrusions, or mandrels. The use of retention devices can facilitate the manufacture of dental articles by machining equipment.

[0198] Examples of useful holding devices are described in U.S. Pat. No. 8,141,217 B2 (Gubler et al.), WO 02 / 45614 A1 (ETH Zurich), DE 20316004 U1 (Stuehrenberg), U.S. Pat. No. 7,985,119 B2 (Basler et al.) or WO 01 / 13862 (3M), the contents of which relating to the description of holding devices are incorporated herein by reference.

[0199] The porous zirconia mill blank can be manufactured as follows.

[0200] The porous zirconia material of dental mill blanks is It can be obtained by a method including the steps of mixing powders of the oxides contained in the material to obtain a powder mixture, and pressing the powder mixture.

[0201] Mixing of the oxide powders can be achieved by shaking the powders or by placing the powders in a mill (e.g., a ball mill) and grinding the powders until a homogeneous powder mixture is obtained. Further possible mixing devices include sieves or granulators.

[0202] To facilitate the pressing process, a pressing aid can be added if desired.

[0203] Suitable pressing aids include binders, lubricants, and mixtures thereof.

[0204] If desired, these additives can be added to the zirconia powder which is the main component of the powder mixture.

[0205] Suitable metal oxide powders are commercially available from a variety of sources, including Tosoh Corporation (Japan).

[0206] The powder mixture is then placed in a mold and pressed into the shape of a dental mill blank.

[0207] The applied pressure is typically in the range of 150-300 MPa, or the applied pressure is adjusted to a level that will allow the pressed ceramic body to have a particular density, e.g., 2.8 g / cm for zirconia ceramic. 3 ~3.5g / cm 3 or 2.85 g / cm 3 ~3.35g / cm 3 is set to reach a density of

[0208] After pressing the powder mixture, the resulting article can be machined or sliced ​​into any desired shape.

[0209] If desired, a calcination step can be carried out.

[0210] In a further step, the pressed composition is subjected to a heat treatment in order to obtain a porous dental mill blank.

[0211] The temperature of the heat treatment is typically within the range of 800 to 1,100°C or 900 to 1,000°C.

[0212] The heat treatment is typically applied for a length of time of 30 to 70 hours or 35 to 60 hours.

[0213] Porous zirconia dental mill blanks are typically provided to customers in a form that allows for mounting of the dental mill blank in a milling machine.

[0214] Either the top or bottom surface of a porous zirconia dental mill blank typically contains marking elements (eg, printed or engraved) that facilitate proper orientation of the dental mill blank in a milling machine.

[0215] The porous dental zirconia article to be sintered is typically prepared according to the following parameters: a) Density: 2.85g / cm 3 ~3.35g / cm 3 , a) BET surface: 5m 2 / g~12m 2 / g, or 5.5m 2 / g~11m 2 / g, either alone or in combination.

[0216] The use of a porous dental zirconia article having a BET surface in the ranges described above has been found to be advantageous for ensuring adequate sintering activity of the material before and during the heat treatment process, particularly during the first heat treatment step having a high heating rate.

[0217] Adequate sintering activity may be necessary to obtain zirconia articles that exhibit the desired translucency within short sintering times.

[0218] Without being bound by any particular theory, it is believed that if the BET surface is too high, many pores will be present in the sintered porous dental zirconia article, which can adversely affect sintering of the article and make it more difficult to achieve a dental zirconia article with adequate strength and / or translucency.

[0219] On the other hand, if the BET surface is too low, the porous zirconia article may not have adequate sintering activity, which may adversely affect the sintering behavior (e.g., sintering shrinkage, outgassing of residual sintering aids) of the porous dental zirconia article during the first heat treatment step.

[0220] Alternatively, or in addition to the BET surface, density may be used to characterize the material of a porous dental zirconia restoration, as density is often related to the total pore volume.

[0221] When referring to a BET surface, it is meant that the surface of the porous zirconia article is not the surface of the powder used to make the article.

[0222] Alternatively, or in addition, the material of the porous dental zirconia article may have the following parameters: a) Biaxial flexural strength: determined according to ISO6872:2015 applying a three-ball punch test adapted for measurement in the porous state (measurement setup: 3.6 mm punch diameter, loading rate 0.1 mm / min, sample thickness 2 mm, support ball diameter 6 mm, diameter of supporting sphere 14 mm) 15-55; b) Vickers hardness: 15 to 150 (HV 0.5) or 20 to 140 (HV 0.5), c) Thermal expansion coefficient: 8.5 x 10 -6 K -1 ~11.5×10 -6 K -1 , either alone or in combination.

[0223] The following combinations of features may be preferred: a) and b), a) and c), a), b) and c).

[0224] If desired, each property can be measured as described in the Examples section.

[0225] If the Vickers hardness of the material is too low, the machinability may be adversely affected (edge ​​chipping or breakage of the workpiece) and, moreover, the ease of manual reworking to individualize dental restorations or frames of monolithic restorations may be impaired.

[0226] If the Vickers hardness of the material is too high, it can increase wear on the machine tool and shorten tool life to unacceptable levels, or the tool can break and destroy the work piece.

[0227] It has been found that if the biaxial bending strength of a material is too low, the material is prone to cracking during milling, during manual finishing by the dental technician, or during firing.

[0228] On the other hand, if the biaxial bending strength of the material is too high, milling the material is often impossible with proper practice. The milling tools used or the milled material may tend to chip or break. In such cases, shaping of the material has had to be achieved by grinding, for example, using a Cerec™ grinding machine (Sirona).

[0229] The material of the porous zirconia dental article includes a ceramic component and a stabilizing component.

[0230] Optionally, colored and fluorescent components may be present.

[0231] The ceramic component is typically selected from oxides of Zr, Hf, Al and mixtures thereof.

[0232] Therefore, in addition to zirconia, the porous zirconia dental mill blank material typically contains oxides of Hf and optionally oxides of Al, typically in minor amounts.

[0233] The stabilizing component is typically selected from oxides of Y, Mg, Ca, Ce, and mixtures thereof (eg, Y2O3, MgO, CaO, CeO2), with the oxide of Y being preferred.

[0234] If present, the coloring components are typically selected from oxides of Fe, Mn, Cr, Ni, Co, Er, Pr, Tb, Nd, in particular oxides of Mn, Er, Pr, Tb, Co and mixtures thereof (e.g. MnO2, Er2O3, Tb4O7, CoO).

[0235] When present, the fluorescent agent is typically selected from oxides, hydroxides, and mixtures thereof of Bi.

[0236] The ceramic component is typically present in an amount of 80-95 wt%, or 85-95 wt%, or 90-95 wt%, based on the weight of the porous dental mill blank.

[0237] The stabilizing component is typically present in an amount of 3 to 12 wt. %, or 5 to 10 wt. %, or 6 to 10 wt. %, based on the weight of the porous dental mill blank.

[0238] When present, the coloring component is typically present in an amount of 0.01 to 2 wt. %, or 0.02 to 1.5 wt. %, or 0.03 to 1.2 wt. %, based on the weight of the porous dental mill blank.

[0239] When present, the fluorescent agent is typically present in an amount of 0 to 1 wt %, or 0.005 to 0.8 wt %, or 0.01 to 0.1 wt %, based on the weight of the porous dental mill blank.

[0240] The weight percentages are calculated based on the amount of each oxide or ceramic component, stabilizing component, coloring component, and fluorescent agent.

[0241] To obtain an aesthetic dental article, the following concentrations have been found to be useful: Ceramic component: 80 to 95% by weight, or 85 to 95% by weight, stabilizing component: 3 to 12% by weight, or 5 to 11% by weight; Coloring component: 0 to 2% by weight, or 0.01 to 1.5% by weight, Fluorescent agent: 0 to 1% by weight, or 0.005 to 0.8% by weight, The weight percentages are based on the weight of the porous dental mill blank.

[0242] According to one embodiment, the material of the porous dental zirconia mill blank is: ZrO2 content: 70 to 98 mol%, or 80 to 97 mol%, HfO2 content: 0 to 2 mol%, or 0.1 to 1.8 mol%, Y2O3 content: 1 to 15 mol%, or 1.5 to 10 mol%, or 2 to 5 mol%, Al2O3 content: 0 to 1 mol%, or 0.005 to 0.5 mol%, or 0.01 to 0.1 mol% can be characterized by

[0243] According to a further embodiment, the material of the porous dental zirconia mill blank is: ZrO2 content: 90-98 mol%, HfO2 content: 0 to 2 mol%, Y2O3 content: 3-5 mol%. Al2O3 content: 0 to 0.1 mol% It is characterized by:

[0244] It has been found that a higher Y2O3 content typically results in an increase in the cubic phase in the zirconia ceramic material after the material is sintered to final density. A higher cubic phase content may contribute to better translucency.

[0245] The porous dental zirconia article materials described herein may contain about 3, 4, or 5 mole percent yttria, and these materials are sometimes referred to as 3Y-TZP, 4Y-TZP, or 5-YTZP materials.

[0246] These materials have been found to be particularly useful in producing aesthetic zirconia restorations in the firing process described herein.

[0247] In another embodiment, the material of the porous dental zirconia article is: ZrO2+HfO2: 90~95% by weight, Y2O3: 4~10% by weight, Al2O3: 0~0.15% by weight, Colored oxide: 0.01~2% by weight, where the weight percentages are based on the weight of the porous dental zirconia article.

[0248] Although the presence of alumina is not required, the presence of small amounts of alumina can be beneficial as it can contribute to better hydrothermal stability of the zirconia article after sintering.

[0249] However, too much alumina can adversely affect the translucency of the sintered zirconia article.

[0250] Thus, alumina may be present in an amount of 0 to 0.15 wt%, or 0 to 0.12 wt%, or 0 to 0.1 wt%.

[0251] The material of the porous zirconia dental article typically does not contain the following components, alone or in combination, in an amount greater than 1 wt. % based on the weight of the material of the porous zirconia dental article, before undergoing a firing process using a glass-containing surface treatment agent: glass or glass ceramic, oxides of Si, Fe, K, Na.

[0252] The presence of these elements can adversely affect the overall performance of the porous dental zirconia article during machining or sintering of the machined article.

[0253] Firing or sintering the pre-sintered zirconia article with the glazing composition can be done by using a conventional sintering protocol or by using a rapid sintering protocol.

[0254] The typical sintering protocol is as follows: Sintering temperature: 1,350℃~1,600℃ Duration: 50 minutes to 360 minutes Heating rate: 1℃ / min~30℃ / min can be characterized by

[0255] The rapid sintering protocol is as follows: Sintering temperature: 1,450℃~1,600℃ Duration: 10 to 40 minutes Heating rate: 60℃ / min~420℃ / min can be characterized by

[0256] A rapid sintering protocol typically includes the following segments: First heat treatment segment: heating rate of 3-7 K / s, duration: not more than 8 minutes; Second heat treatment segment: heating rate of 0.2-1.0 K / s or 0.3-0.6 K / s, duration: 25 min or less; Third heat treatment segment: heating rate of about 0 K / s, duration: 8 minutes or less, or 5 minutes or less, or 3 minutes or less; Cooling segment: Cooling rate ≥ 3K / sec, duration ≤ 6 minutes.

[0257] The use of a rapid sintering protocol is sometimes preferred as it allows the production of dental zirconia restorations in a shorter period of time and with less labor.

[0258] An oven that can be used in the methods described herein is commercially available from Dentsply Sirona (SpeedFire™).

[0259] A suitable furnace is also described in WO 2017 / 144644 ​​A1 (Sirona). This furnace is for carrying out heat treatment of dental replacement parts and comprises an induction coil, a duplicating heater, an insulating layer, and a furnace chamber. Furthermore, the furnace has a cooling system for controlling the internal temperature of the furnace chamber.

[0260] The present invention further relates to zirconia dental restorations obtainable or obtainable by the methods described herein.

[0261] Sintered dental zirconia articles obtained by the methods described herein typically have the following properties: a) density: at least 98.5 (in some embodiments, about 99, 99.5, 99.9, or even at least about 99.99) percent of theoretical density; b) Biaxial flexural strength: 500 to 1,500 MPa, or 800 to 1,400 MPa, measured in accordance with ISO 6872:2015; c) Vickers hardness: 450 MPa to 2,200 MPa, or 500 MPa to 1,800 MPa HV(2); d) phase content tetragonal phase: 10 to 80% by weight, or 20 to 70% by weight, or 40 to 70% by weight; e) cubic phase content: 10 to 80% by weight, or 20 to 70% by weight, or 30 to 60% by weight; f) Transmittance: 25% or more when measured on a sample having a thickness of 1 mm in reflection mode at a wavelength of 450 nm to 800 nm; g) Tooth color may be characterized by the following alone or in combination:

[0262] The following combinations of features may be preferred: a) and b), a) and c), a), d), and e), or a), b), d), e), and f).

[0263] If desired, each property can be measured as described in the Examples section.

[0264] These characteristics refer to dental zirconia articles that are sintered without a glazing composition.

[0265] The shape of the sintered dental zirconia article is not particularly limited.

[0266] Sintered dental zirconia articles typically have the shape of a dental bridge, veneer, facing, coping, crown, abutment, monolithic dental restoration, or portion thereof.

[0267] The present invention also relates to a kit of parts.

[0268] The kit of parts includes a glazing composition as described herein and a dental zirconia mill blank.

[0269] The kit of parts typically provides the physician with instructions for use.

[0270] The instructions include hints on what the parts kit is intended to be used for, how it should be machined, and what sintering conditions should be applied.

[0271] If desired, a parts kit may be provided containing the following items: sintering aids, application equipment for surface treatment agents, Optionally, a shade guide, optionally, a grinding aid; optionally a sintering oven, may further include one or more of:

[0272] Sintering aids include, for example, sintering beads and other devices suitable for mechanically supporting the article being sintered during the sintering process.

[0273] Application implements include, for example, brushes, brush pens, sponges, and spray guns.

[0274] Further embodiments of the present invention are outlined below.

[0275] Embodiment 1: 1. A method for producing a dental zirconia restoration, comprising: providing a porous dental zirconia article; applying a glazing composition described herein to at least a portion of a surface of a porous dental zirconia restoration; and sintering the porous dental zirconia article with the glazing composition on its surface to final density; The porous dental zirconia article comprises: Biaxial flexural strength: 15-55, measured according to ISO6872:2015 Density: 2.85g / cm 3 ~3.35g / cm 3 , characterized by The glazing composition comprises: Liquid: 60% to 95% by weight, Glass particles: 4% by weight to 40% by weight, Hydrophilic nano-sized silica particles: 0.1% by weight to 5% by weight, wherein the weight percentages are based on the weight of the total composition.

[0276] Embodiment 2: 1. A method for producing a dental zirconia restoration, comprising: providing a porous dental zirconia article; applying a glazing composition described herein to at least a portion of a surface of a porous dental zirconia restoration; and sintering the porous dental zirconia article with the glazing composition on its surface to final density; The porous dental zirconia article comprises: Biaxial flexural strength: 15-55, measured according to ISO6872:2015 Density: 2.85g / cm 3 ~3.35g / cm 3 , characterized by The glazing composition comprises: Liquid: 60% to 95% by weight, Glass particles: 4% by weight to 40% by weight, Hydrophilic silica nanoparticles: 0.1% by weight to 5% by weight, wherein the weight percent is based on the weight of the entire composition; Sintering is carried out under the following conditions: Sintering temperature: 1,350℃~1,600℃ Duration: 50 minutes to 360 minutes The method is carried out by applying a heating rate of 1°C / min to 30°C / min.

[0277] Embodiment 3: 1. A method for producing a dental zirconia restoration, comprising: providing a porous dental zirconia article; applying a glazing composition described herein to at least a portion of a surface of a porous dental zirconia restoration; and sintering the porous dental zirconia article with the glazing composition on its surface to final density; The porous dental zirconia article comprises: Biaxial flexural strength: 15-55, measured according to ISO6872:2015 Density: 2.85g / cm 3 ~3.35g / cm 3 , characterized by The glazing composition comprises: Liquid: 60% to 95% by weight, Glass particles: 4% by weight to 40% by weight, Hydrophilic silica nanoparticles: 0.1% by weight to 5% by weight, wherein the weight percentages are based on the weight of the total composition; Sintering is carried out under the following conditions: Sintering temperature: 1,450℃~1,600℃ Duration: 10 to 40 minutes The method is carried out by applying a heating rate of 60°C / min to 420°C / min.

[0278] The entire disclosures of all patents, patent documents, and publications cited herein are incorporated by reference in their entireties, as if each were individually incorporated. Various modifications and variations to the present invention will be apparent to those skilled in the art without departing from the scope and spirit of the invention. The above specification, examples, and data provide a description of the manufacture and use of the compositions and methods of the invention. The invention is not limited to the embodiments disclosed herein. Those skilled in the art will recognize that many alternative embodiments of the invention can be made without departing from the spirit and scope of the invention.

[0279] The following examples are presented to illustrate the present invention. [Example]

[0280] Unless otherwise indicated, all parts and percentages are by weight, all water is deionized (DI), and all molecular weights are weight average molecular weight. Furthermore, unless otherwise indicated, all experiments were conducted under ambient conditions (23° C., 1013 mbar).

[0281] method BET surface The BET surface of a porous article is typically measured as follows: total pore volume and average pore diameter can be analyzed using N2 adsorption isotherms and BET surface area analysis. Approximately 0.1-2 g samples were cut from larger samples, if necessary, to fit into straight tubes. All samples were vacuum degassed at 120°C for >1 hour before analysis. Samples were then analyzed by N2 gas adsorption and desorption using a Belsorb II (distributed by Robotherm Prazisionsmesstechnik, Bochum, Germany) with a 9 mm cell, 2 cm bulb, and 5 mm glass rod. At liquid nitrogen temperatures, adsorption data points are collected between 0.1 and 0.99 p / p0, and desorption data points are collected between 0.99 and 0.5 p / p0. The specific surface area S is calculated by the BET method with p / p0 0.25 to 0.3 (for details, refer to Chapter 12 on the calculation of Belsorb Analysis Software User Manual Operating Manual, Chapter 12, Bel Japan.INC).

[0282] How to measure translucency (TL) If desired, the translucency of a ceramic article can be evaluated by the following procedure: provide a test specimen in the shape of a disk with a thickness of approximately 1±0.05 mm and a measurement area of ​​at least 12 mm in diameter. To prepare the test specimen, the pre-sintered sample is sawed into wafers with a thickness of approximately 1.3 mm using a dry cutting saw. The parallel large faces of the wafer are ground using silicon carbide abrasive paper (P2500). The ground sample is sintered in a suitable furnace into a sintered sample with a thickness of 1±0.05 mm. The sintered sample is measured as fired using a spectrophotometer (X-Rite Color i7, Grand Rapids, USA) in reflection mode against white and black backgrounds to obtain the opacity of the material. The translucency is calculated according to T=1-opacity. A higher translucency value indicates a higher light transmittance and a lower opacity.

[0283] If desired, L * a * b* The value can be determined in addition to the opacity using the same device.

[0284] Particle size (suitable for micro-sized particles) If desired, particle size distribution, including mean particle size, was determined using a Cilas 1064 (FA. Quantacrome) particle size detection device.

[0285] porosity If desired, porosity can be determined as follows: Porosity = (1 - (density of porous material / density of sintered material)) x 100. The density of a porous material can be calculated by dividing the weight by the volume. The volume can be obtained by geometric measurement.

[0286] density If desired, the density of the sintered material can be measured by the Archimedes method. This measurement is performed on a precision balance (e.g., "BP221S" from Sartorius AG, Göttingen, Germany) using a density measurement kit (e.g., "YDK01" from Sartorius AG). In this procedure, the sample is first weighed in air (A) and then immersed in water (B). The water is a 0.05 wt. % Tenside solution (e.g., "Berol 266" from Fa. Hoesch). The density is calculated using the formula ρ = (A / (AB))ρ, where ρ is the density of water. The relative density can be calculated by reference to the theoretical density (ρ) of the material. rel =(ρ / ρt)100.

[0287] Glass viscosity / surface tension If desired, the viscosity and surface tension of the glass can be calculated from SciGlass using software tools. More specifically, the following software tool was used to calculate the properties of the glass compositions described herein: SciGlass Professional, Version 7.12, Model Priven 2000.

[0288] Viscosity of the composition If desired, the viscosity of the composition was measured using a Physica MCR301 rheometer (Anton Paar, Graz, Austria) with a cone / plate geometry at a constant shear rate of 616 s while rotating at 23°C. -1 The diameter of the cone / plate is 25 mm and the gap is set to 0.05 mm.

[0289] Haze and gloss determination The haze and gloss of the glaze of the sintered dental zirconia article can be evaluated under standardized lighting conditions (light box Spectramax™ III from X-rite, lighting set to daylight D65).

[0290] Determining the effectiveness of binders The binder effectiveness of the hydrophilic binder component was evaluated as follows: A portion of the glazing composition was applied to the surface of a porous zirconia sample. After 5 seconds, the sample was touched with a finger (3 times).

[0291] Sticking of glass particles of the glazing composition to the finger was considered a negative result, while lack of sticking was considered a positive result.

[0292] Determining the homogeneity of glazing compositions and sintered zirconia articles If desired, the homogeneity of the sintered glass (e.g., the presence of bubbles) can be analyzed by dark-field illumination microscopy.

[0293] material

[0294] [Table 3]

[0295] Method for preparing a glazing composition The components of the composition were mixed using a magnetic stirrer.

[0296] Glass Preparation Method Glass powders G1, G2, and G3 were prepared as follows: Each oxide was weighed and filled into a PP bottle. IPA was added until a slurry was obtained. Zirconia grinding media was added, and the mixture was rolled on a roller mill overnight. The mixture was sieved into a plastic Petri dish and allowed to dry. The dried powder was filled into an alumina crucible and calcined at 800°C for 2 hours. The calcined powder was filled into a Pt / Rh crucible, heated to 1,550°C, and held at 1,550°C for 2 hours. The molten glass was rapidly cooled by quenching in DI water. The glass was crushed and ball milled to obtain a crushed glass powder with an average particle size of 2.5 μm.

[0297] The glass powder used had the following composition and properties:

[0298] [Table 4]

[0299] Method for preparing zirconia articles Mill blank samples were made from 4Y-TZP powder with the following composition: ZrO2: 90.71 wt%, Y2O3: 7.24 wt%, Al2O3: 0.06 wt%.

[0300] The following steps were applied: filling the powder composition into a mold, applying pressure (200 MPa) to the powder charge, demolding the compact, and applying a heat treatment at 970° C. for about 2 hours. Plaques were cut to a thickness of 1.3 mm from the heat-treated mill blank samples (dimensions 19.5 mm × 39.5 mm × 16.0 mm).

[0301] How to apply The composition to be tested was applied with a brush onto one-half of the surface of a porous zirconia sample plaque. The plaque was allowed to dry for 3 minutes before being placed in a fast firing oven (Dentsply Sirona).

[0302] Firing Process The surface treated test samples were heat treated using a CEREC SpeedFire™ furnace from Dentsply Sirona according to the following sintering protocol: RT~400℃: Heating rate: 5.3℃ / sec 400℃~1350℃: Heating rate: 5.3℃ / sec 1350℃~1580℃: Heating rate: 0.5℃ / sec; Hold for 120 seconds 1580℃~1000℃: Heating rate: -3.2℃ / sec; Hold for 10 seconds 1000℃~950℃: Heating rate: -0.3℃ / sec

[0303] After cooling, the samples were examined for haze and gloss.

[0304] Invention Example 1 A slurry was made by mixing 0.700 g of glycerol, 0.002 g of silane-treated fumed silica (HDK-H2000), 0.018 g of non-silane-treated fumed silica (Ox50), <0.001 g of colorant E142, and 0.280 g of G1 glass powder. The viscosity of this composition was measured to be 150 mPa. * The slurry was applied as described in the Application Methods and then sintered using the sintering program described. The resulting platelets were translucent and the glaze thereon had a smooth surface finish with only slight haze.

[0305] Comparative Example 1 A slurry was made by mixing 1.750 g of glycerol, 0.025 g of silane-treated fumed silica (HDK-H2000), <0.001 g of colorant E142, and 0.750 g of G1 glass powder. The resulting restoration was translucent, the glaze appeared quite hazy, and had a smooth surface finish.

[0306] Comparative Example 2 A slurry was made by mixing 0.700 g of glycerol, 0.020 g of silane-treated fumed silica (HDK-H2000), <0.001 g of food coloring E142, and 0.280 g of G1 glass powder. The viscosity of this composition was measured to be 2,214 mPa. * The resulting plaques were translucent and the glaze had a smooth surface finish with only slight haze.

[0307] Invention Example 2 A slurry was made by mixing 18,000 g of deionized water, 0.075 g of xanthan, 0.074 g of non-silane treated fumed silica (Ox50), 0.001 g of food coloring E142, and 1.850 g of G1 glass powder. The viscosity of this composition was measured to be 16 mPa. * The resulting restoration was translucent and the glaze appeared transparent and had a glossy, smooth surface finish.

[0308] Comparative Example 3 A slurry was made by mixing 18,000 g of deionized water, 0.075 g of xanthan, 0.001 g of food coloring E142, and 1.924 g of G1 glass powder (a high melting point glaze material). The viscosity of this composition was measured to be 16 mPa. * The resulting restoration was translucent and the glaze appeared transparent but had a partially matte surface finish with little gloss.

[0309] Composition and Results

[0310] [Table 5]

[0311] The use of hydrophilic silica nanoparticles helps to anchor the glass particles to the surface of the porous dental zirconia article, and when touching the outside of the dental restoration, very few glass particles are left on the fingers.

[0312] High melting point glaze materials tend to be hazy, which can be improved by adding silica nanoparticles to the glazing composition.

[0313] High melting point glaze materials can be dull, which can be improved by adding silica nanoparticles to the glazing composition.

Claims

1. 1. A glazing composition for a porous dental zirconia article, comprising: Liquid and glass particles containing 80% to 98% by weight of SiO 2 ; Hydrophilic silica nanoparticles characterized by: Not silane treated, A particle size (D 50 ) of 10 nm to 70 nm, and BET surface area of ​​20 m 2 / g to 500 m 5 / g and wherein the hydrophilic silica nanoparticles are present in an amount of 0.1% to 5% by weight based on the weight of the glazing composition.

2. A glazing composition as described in claim 1, wherein the hydrophilic silica nanoparticles and the glass particles are present in a weight ratio of 1:40 to 1:

5.

3. The glazing composition of claim 1 , wherein the liquid is a polar liquid selected from water, alcohols, polyols, and combinations thereof.

4. The glass particles have the following characteristics: being present in an amount of 5 to 40 wt. %; Viscosity: at least 10 at a temperature of 1,300°C ４ Pa ＊ s, Thermal expansion coefficient: 1 x 10 －６ K －１ ~10 x 10 －６ K －１ , Surface tension: 210 mN / m to 300 mN / m at 1,300°C, Littleton softening point viscosity at temperatures between 1,100°C and 1,350°C; Pour point viscosity at temperatures between 1,300°C and 1,650°C; Particle size (D) ５０ ): 1μm~40μm, 10. The glazing composition of claim 1, characterized by: alone or in combination, the weight percentages being based on the weight of the glazing composition.

5. The glass particles have the following composition: Table 1 10. The glazing composition of claim 1, characterized by having any of the following:

6. The glazing composition comprises: the liquid in an amount of 60% to 95% by weight, The glass particles in an amount of 4% to 40% by weight 10. The glazing composition of claim 1, wherein the weight percentages are based on the weight of the glazing composition.

7. Features include: Viscosity: 10 mPa at 23°C ＊ s~3,000mPa ＊ s, pH value: 6-9, The glazing composition of claim 1 characterized by:

8. The method of claim 7, wherein the liquid is selected from water, an alcohol, a polyol, and combinations thereof and is present in an amount of 60% to 95% by weight; the glass particles are present in an amount of 4% to 40% by weight; The glass particles have a particle size (D ５０ ) The glass of the glass particles is 10 ４ Pa ＊ s to 10 ７ Pa ＊ characterized by a viscosity of s, The glazing composition of claim 1 , wherein the weight percentages are based on the weight of the glazing composition.

9. The glazing composition of claim 1, wherein the glass particles further comprise B 2 O 3 , Al 2 O 3 , or a combination thereof.

10. 1. A method for making a dental zirconia article, comprising: providing a porous dental zirconia article; applying a glazing composition according to any one of claims 1 to 9 to at least a portion of the surface of a porous dental zirconia restoration; and c) sintering the porous dental zirconia article with the glazing composition on its surface to final density.

11. The porous dental zirconia article has the following characteristics: Biaxial bending strength: 15-55, measured according to ISO6872:2015 Vickers hardness: 15 to 150 (HV0.5), 11. The method of claim 10, characterized by:

12. sintering the porous dental zirconia article under the following conditions: For normal sintering, Sintering temperature: 1,350°C to 1,600°C, Duration: 50 to 360 minutes, Heating rate: 1℃ / min - 30℃ / min, For high speed sintering, Sintering temperature: 1,450°C to 1,600°C, Duration: 10 to 40 minutes Heating rate: 60℃ / min - 420℃ / min, The method according to claim 10, characterized by any one of the following:

13. providing a porous dental zirconia article having a biaxial flexural strength of 15 to 55 as measured in accordance with ISO 6872:2015; applying a glazing composition according to any one of claims 1 to 9 to at least a portion of the surface of the porous dental zirconia restoration; sintering the porous dental zirconia article with the glazing composition thereon to final density; The method of claim 10, comprising:

14. A parts kit, A glazing composition according to any one of claims 1 to 9; a dental zirconia mill blank suitable for producing dental restorations; Optionally, alone or in combination: sintering aids application equipment for surface treatment agents, Shade guide, Grinding aids, sintering oven, Includes parts kit.

15. Use of hydrophilic silica nanoparticles as a binder to produce a glazing composition described in any one of claims 1 to 9 in a method for producing a dental zirconia article.

Images