Method for generation of opalescence in dental restorations

Abstract

To provide a new, efficient, and effective way of achieving opalescence in dental materials, and to provide dental materials and restorations having such opalescent qualities.SOLUTION: Disclosed herein are methods for creating opalescence in dental materials and restorations, compositions used in such methods, and the resultant dental materials and restorations. More particularly, the opalescence may be created by directly embedding opalescent particles into a matrix material. In some embodiments, photonic crystals are embedded in the dental material to achieve the opalescent effect. Photonic crystal particles may be embedded in dental materials matrices such as ceramics, composites, and polymers, and can generate opalescence in the materials. Some embodiments disclose compositions for applying the opalescence to a dental restoration.SELECTED DRAWING: Figure 1a

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of priority to U.S. Patent Application Serial No. 62 / 806,192, filed February 15, 2019, entitled "Method of Producing Opulence in Dental Restorations," the entire contents of which are incorporated herein by reference.

[0002] The present disclosure relates to dental materials and restorations, and methods for producing opalescence in such dental materials and restorations. More specifically, opalescence can be created by embedding opalescent particles directly into a matrix material. In some embodiments, photonic crystals are embedded in dental materials to achieve the opalescent effect. Photonic crystal particles can be embedded in dental material matrices, such as ceramics, composites, polymers, etc., to produce opalescence in the material. [Background technology]

[0003] Opalescence is a term that describes the optical characteristics of opal. The term refers to the change in color that can be seen when opal is viewed in different lighting situations; opal appears one color in reflected light and its complementary color in transmitted light. That is, light reflected from the opal's surface is one color, and light that passes through the opal is its complementary color.

[0004] Natural teeth have opalescence due to light scattering caused by hydroxyapatite nanocrystals. When incident light penetrates a tooth, blue light is preferentially scattered back to the side where the light strikes, giving the tooth a bluish-white appearance. However, in thin areas, light can pass through the tooth and is opalescent, so the areas through which the light penetrates appear red to orange in color. The opalescence of natural teeth comes from both the enamel and dentin, but the enamel is the primary source of opalescence.

[0005] Similarly, an opalescent effect can be created in dental materials by carefully controlling how light is scattered by that material. There are several known methods to achieve this effect, most of which require nanoscale particles to scatter the light.

[0006] One method of creating opalescent materials is by the nucleation and growth of nano-sized crystals in a matrix phase. By controlling the size of the crystals, the wavelength (and therefore color) of the scattered light can be modulated. However, achieving opalescence in this way requires very precise control of the temperature and hold times in the nucleation and growth cycles, and in the subsequent thermal cycles, or the opalescent effect will be lost. Therefore, this method is not suitable for all situations where opalescent materials may be required.

[0007] Another method involves mixing nanoparticles with a matrix material. This method has its own challenges; the nanoparticles must be well dispersed within the matrix, and they easily agglomerate during mixing or heat treatment. The agglomerated particles cause random scattering of light, resulting in a material that appears white and opaque, rather than the desired opalescence.

[0008] A different approach to producing opalescent substances, especially ceramic materials, uses nanoparticles as starting materials. With this technique, nano-sized powders are compressed and sintered like conventional ceramic powders. If the optical properties of the ceramic are suitable and the final grain size can be kept below 400 nm, opalescent ceramics can be produced. However, it is very difficult to keep the grain size small and uniform by using conventional sintering processes. Non-conventional sintering techniques such as hot isostatic pressing or plasma-assisted sintering, which are usually carried out at lower temperatures with lower hold times than conventional sintering, are required.

[0009] Applicant has invented a new, efficient and effective method for achieving opalescence in dental materials, and dental materials and restorations having such opalescent properties. This new method offers distinct advantages over the prior art. All of the above methods require much more careful control of manufacturing parameters such as time, temperature and particle size distribution than the method disclosed herein.

[0010] Furthermore, all of the above methods achieve opalescence through highly controlled scattering of light by either second phase particles or grain boundaries, which increases the opacity of the material. As a result, it is not possible to achieve an opalescent effect in very thin sections of translucent material using these methods. The present invention is particularly well suited to creating translucent materials that exhibit opalescence at very thin (0.1 to 0.5 mm) thicknesses, such as those used in aesthetic dental restorations. Summary of the Invention

[0011] In the present disclosure, opalescence is achieved by incorporating photonic crystal particles into dental materials. Previously, dental materials were imparted with opalescence by controlling scattering through careful distribution of second phases or by precisely controlling the microstructure. The embodiments described herein do not rely on either of these ideas, but instead utilize photonic crystal particles that reflect light of a specific color rather than scattering a wide range of wavelengths. The intensity of reflected light by photonic crystals is much stronger than can be achieved by scattering. Thus, strong opalescence can be achieved even in very thin films, such as layers of glaze ceramics applied to dental restorations.

[0012] Some embodiments provide a dental material that includes one or more dental matrices; and one or more photonic crystals.

[0013] In some embodiments, the one or more dental matrices include a dental glaze, a dental porcelain, a dental ceramic, a dental composite, a dental resin, a dental polymer, or a combination thereof.

[0014] In some embodiments, the dental ceramic comprises at least one of alumina, zirconia, glass ceramic, leucite reinforced glass, glass infiltrated ceramic, or a mixture or solid solution of two or more thereof.

[0015] In some embodiments, the photonic crystal is a synthetic opal.

[0016] In some embodiments, the photonic crystal is a synthetic opal that is partially or fully infiltrated with a ceramic material, an organic material, an organic-inorganic hybrid material, or a mixture of two or more thereof.

[0017] In some embodiments, the permeable ceramic material comprises one or more of alumina, zirconia, titania, silica, yttria, zinc oxide, hafnia, tin oxide, indium oxide, ceria, niobium oxide, tantalum oxide, germanium oxide, gallium oxide, and scandium oxide.

[0018] In some embodiments, the permeable ceramic material comprises one or more materials that can be converted to alumina, zirconia, titania, silica, yttria, zinc oxide, hafnia, tin oxide, indium oxide, ceria, niobium oxide, tantalum oxide, germanium oxide, gallium oxide, scandium oxide, or a mixture or solid solution of two or more thereof when subjected to chemical treatment, heat treatment, light treatment, pressure treatment, or a combination of two or more treatments.

[0019] In some embodiments, the organic-inorganic hybrid material comprises one or more materials that can be converted to alumina, zirconia, titania, silica, yttria, zinc oxide, hafnia, tin oxide, indium oxide, ceria, niobium oxide, tantalum oxide, germanium oxide, gallium oxide, scandium oxide, or a mixture or solid solution of two or more thereof upon chemical treatment, heat treatment, light treatment, pressure treatment, or a combination of two or more treatments. In some embodiments, the organic material of the organic-inorganic hybrid material consists of one or more monomers or polymers, or a mixture of at least one monomer and one polymer.

[0020] In some embodiments, the photonic crystal is an inverse opal.

[0021] In some embodiments, the inverse opal is made of a ceramic material, an organic material, an organic-inorganic hybrid material, or a mixture of two or more thereof.

[0022] Some embodiments provide a method of making a dental material that includes combining one or more photonic crystals with one or more dental matrices.

[0023] In some embodiments, the one or more dental matrices are dental glazes, dental porcelains, dental ceramics, dental composites, dental resins, dental polymers, or combinations thereof.

[0024] In some embodiments, the dental ceramic comprises at least one of alumina, zirconia, glass ceramic, leucite reinforced glass, glass infiltrated ceramic, and mixtures or solid solutions of two or more thereof.

[0025] Some embodiments provide a composition for imparting opalescence to a dental restoration, the composition comprising a ceramic component, an opal component, and a liquid component.

[0026] In some embodiments, the composition comprises about 50-85% by weight ceramic component; about 1-20% by weight opal component; and the balance liquid component.

[0027] In some embodiments, the ceramic component is ceramic-based, present at about 50-85% by weight.

[0028] In some embodiments, the opal component is present at about 2-6% by weight.

[0029] In some embodiments, the opal component is present at about 6-12% by weight.

[0030] In some embodiments, the ceramic component is a glaze base present at about 50-65% by weight.

[0031] In some embodiments, the opal component is present at about 6-15% by weight.

[0032] Some embodiments include less than about 2% by weight of a viscosity modifier.

[0033] Some embodiments include less than about 1% by weight of a fluorescent agent.

[0034] Some embodiments include less than about 2% by weight of a viscosity modifier; and less than about 1% by weight of a fluorescent agent. [Brief description of the drawings]

[0035] [Figure 1a] Figure 1a shows the light scattering effect of various materials. [Figure 1b] Figure 1b shows the light scattering effect of various materials. [Figure 1c] Figure 1c shows the light scattering effect of various materials. [Figure 1d] FIG. 1d illustrates the effect achieved by the methods and materials herein. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0036] According to the methods described herein, opalescence can be created by embedding opalescent particles directly into a matrix material. In particular, photonic crystals can be embedded into dental materials to achieve the opalescent effect. This disclosure relates to the use of photonic crystals as opalescent agents in dental materials.

[0037] Photonic crystal particles can be embedded in a dental material matrix, such as a ceramic, composite, or polymer, to produce opalescence in the material.

[0038] A crystal is a material in which atoms or molecules are arranged in a periodic pattern.

[0039] A photonic crystal is a regular structure in which the refractive index varies periodically on length scales comparable to the wavelength of the light of interest. Just as electrons are subject to a periodic potential in a conventional crystal, light experiences a periodic potential as it propagates through a photonic crystal. The periodic potential in a photonic crystal is due to a lattice of dielectric material, not atoms or molecules. Light in a photonic crystal is forbidden to propagate in certain directions within certain energies. In other words, light is reflected in certain directions. If the incident light is white light, light in a certain wavelength range is reflected. The angle and wavelength range are controlled by the effective refractive index and the periodicity. Depending on the number of dimensions in which the photonic crystal has periodicity, there are one-dimensional, two-dimensional, and three-dimensional photonic crystals.

[0040] Photonic crystals formed from colloidal particles are called colloidal crystals or synthetic opals. Synthetic opals can be made by packing colloidal particles into ordered structures. Packing can be done by sedimentation, controlled drying, selective deposition on pre-patterned sites, injection of droplets of a colloidal suspension into air or other immiscible liquid followed by drying, or centrifugation of the colloidal suspension. Centrifugation is the fastest way to make photonic crystals in large quantities. Silica and polymer spheres are most frequently used for synthetic opals.

[0041] In addition to synthetic opals, there are other types of photonic crystals that can be used to create opalescence effects. For example, synthetic opals can be used as a framework to create what are called "inverse opals." Inverse opals are created by infiltrating a synthetic opal with a different material (e.g., titania, silica, zirconia, or a polymer) and then removing the silica or polymer lattice by chemical dissolution or pyrolysis.

[0042] A third type of photonic crystal can be created by partially or completely infiltrating the lattice of a synthetic opal with a different material, for example titania, silica, zirconia or a polymer, but not inverting the structure by removing the synthetic opal.

[0043] The characteristic reflection color of a photonic crystal depends on the effective refractive index of the crystal and the periodicity of the lattice. Therefore, by changing the effective refractive index, either by infiltrating a synthetic opal or by inverting the opal, the characteristic reflection color of the crystal can be changed. Similarly, the periodicity of the crystal can be controlled by changing the diameter of the spheres used to create the crystal. Equation (1) is the equation for the reflection peak of a synthetic opal, a partially or fully infiltrated opal, or an inverse opal with a face-centered cubic lattice.

[0044]

number

[0045] where d is the lattice spacing, n eff is the effective refractive index, D is the particle diameter, Φ is the volume fraction of the particle, n p and m is the refractive index of the medium that fills the particles and voids. This formula provides guidance on how a desired reflected wavelength can be achieved by choosing the material and size of the spheres.

[0046] As described herein, synthetic opals and infiltrated synthetic opals were used to demonstrate the use of photonic crystals as opalescent agents in dental applications such as ceramics, composites, and polymers. The synthetic opals were formed by centrifugation of a silica sphere suspension.

[0047] General procedure for producing synthetic opals.

[0048] Silica spheres having either about 180 nm size or 220 nm size (other sizes can be used) and ethanol were added to each centrifuge tube to make a 20 wt% ethanol suspension of silica spheres. The size of the silica spheres affects the periodicity which affects the wavelength of the reflected light, so the silica spheres can be selected to any size based on the desired light. For example, silica spheres range in size from about 140 nm to about 370 nm.

[0049] The size and reflectance of the silica spheres determine the reflected wavelength (and therefore the reflected color). The suspension was sonicated to break up the silica sphere agglomerates. Centrifugation at low speed was performed to remove large agglomerates from the suspension. The supernatant suspension was decanted and transferred to another centrifuge tube. It was sonicated again and centrifuged at high speed to form the synthetic opal. The ethanol was decanted and the synthetic opal was dried at room temperature. The dried synthetic opal was heated at 600°C for 4 hours to allow consolidation of the opal. The synthetic opal was then further processed to prepare the opalescent dental material.

[0050] In its most general sense, the method herein incorporates synthetic opals, ie, photonic crystals, into dental materials through blending and other techniques.

[0051] Some methods include the use of glazing powders. Glazing powders are uncolored, transparent glazing porcelains of appropriate firing temperature. Any glazing powder suitable for use in dental restorations can be used. In some cases, synthetic opals can be incorporated into the glaze paste product.

[0052] In some embodiments, the photonic crystals can be mixed with a glazing powder, to which an organic liquid can be added later to obtain a paste.

[0053] In other embodiments, photonic crystals can be added to existing paste glaze products.

[0054] Glazing powder or paste glaze products, including but not limited to layering materials, glazing materials, and structure building materials, are suitable for use with dental restorations.

[0055] In some embodiments, the photonic crystal powder can be incorporated into any dental ceramic, polymer, resin, composite, or other dental material.

[0056] Examples 1 and 5 below describe how to make a glaze that can impart opalescence properties when applied to a zirconia restoration and fired. Heat treated opal obtained from the general procedure was ground into a powder. Opal powders smaller than 63 μm were further ground into smaller particles in an ethanol suspension. The particles were dried. Opal powder and glazing powder were mixed in a ratio of about 1:9 parts by weight. A range of about 1:1 to about 1:199 by weight can be used. In some embodiments, the range is about 1:2 to about 1:99. In some embodiments, the range is about 1:3 to about 1:49. The mixed powders were made into a paste and applied to the zirconia restoration. The glaze layer containing the opal particles was fired according to the firing schedule for the glaze.

[0057] In Examples 2 and 6, the heat treated opal chunks (i.e., agglomerated) were infiltrated with titania as follows: The chunks were soaked in titanium isopropoxide for 2-10 hours and dried. In some embodiments, the chunks were placed in isopropoxide for about 4 hours. The dried chunks were heated at 600°C for 1 hour to obtain titania infiltrated opal chunks. The titania infiltrated opal chunks were ground into a powder. The titania infiltrated opal powders smaller than 63 μm were further ground into smaller particles in an ethanol suspension. The particles were dried. The titania infiltrated opal powder and the glazing powder were mixed in a ratio of about 1:9 parts by weight. A range of about 1:1 to about 1:199 by weight can be used. In some embodiments, the range is about 1:2 to about 1:99. In some embodiments, the range is about 1:3 to about 1:49. The mixed powders were made into a paste and applied to the zirconia restoration. The glaze layer containing the opal particles was fired according to the glaze firing schedule.

[0058] In Examples 3 and 8, the heat treated opal chunks were subjected to double titania infiltration. The heat treated opal chunks were infiltrated with titanium isopropoxide for 2-10 hours and dried. In some embodiments, the chunks were left in isopropoxide for about 4 hours. The dried chunks were heated at 600°C for 1 hour to obtain titania infiltrated opal chunks. The titania infiltrated opal chunks were subjected to the titania infiltration process once again. In some embodiments, the infiltration step can be repeated 2 to 5 times. The double infiltrated chunks were ground into powder. Opal powders smaller than 63 μm were further ground into smaller particles in an ethanol suspension. The particles were dried. The titania double infiltrated opal powder and glazing powder were mixed in a ratio of about 1:9 parts by weight. A range of about 1:1 to about 1:199 by weight can be used. In some embodiments, the range is about 1:2 to about 1:99. In some embodiments, the range is from about 1:3 to about 1:49. The mixed powders were made into a paste and applied to the zirconia restoration. The glaze layer containing the opal particles was fired according to the firing schedule for the glaze.

[0059] In Examples 4 and 8, the heat treated opal chunks were subjected to dual titania infiltration and hydrolysis of titanium isopropoxide prior to post heat treatment. The heat treated opal chunks were infiltrated with titanium isopropoxide for 2-10 hours and allowed to dry. In some embodiments, the chunks were left in the isopropoxide for about 4 hours.

[0060] The dried chunks were soaked in water to hydrolyze the titanium isopropoxide and then heated at 600 °C for 1 h to produce titania-infiltrated opal chunks. The hydrolysis of titanium isopropoxide can prevent the generation of carbon residue after heat treatment. The titania-infiltrated opal chunks were subjected to the titania infiltration and hydrolysis process once again.

[0061] In some embodiments, the infiltration step may be repeated 2 to 5 times. The doubly infiltrated chunks were ground into a powder. Opal powders smaller than 63 μm were further ground into smaller particles in an ethanol suspension. The particles were dried. The titania doubly infiltrated opal powder and glazing powder were mixed in a ratio of about 1:9 parts by weight. A range of about 1:1 to about 1:199 by weight can be used. In some embodiments, the range is about 1:2 to about 1:99. In some embodiments, the range is about 1:3 to about 1:49. The mixed powders were made into a paste and applied to the zirconia restoration. The glaze layer containing the opal particles was fired according to the firing schedule for the glaze. EXAMPLES

[0062] Example 1: 180 nm milled opal powder with dental glazing powder 7 g of silica spheres with a size of about 180 nm and 28 g of ethanol were added to each centrifuge tube to make a 20 wt% suspension of silica spheres in ethanol. The suspension was sonicated to break up the agglomerates of silica spheres. Centrifugation at low speed was performed to remove larger particles from the suspension. The supernatant suspension was decanted and transferred to another centrifuge tube. It was sonicated again and centrifuged at high speed to form synthetic opal. The ethanol was decanted and the synthetic opal was dried at room temperature. The dried synthetic opal was heated at 600°C for 4 hours to consolidate the opal. The heat-treated opal obtained by the general procedure was crushed into powder. The opal powder less than 63 μm was further crushed in ethanol suspension to make smaller particles. The particles were dried. 5 g of opal powder was mixed with 45 g of glazing powder. The mixed powder was made into a paste and applied to the zirconia restoration. The glaze layer containing the opal particles was fired according to the firing schedule of the glaze.

[0063] Example 2: Titania penetration of synthetic opals - 180 nm 7 g of silica spheres with a size of about 180 nm and 28 g of ethanol were added to a centrifuge tube to make a 20 wt% suspension of silica spheres in ethanol. The suspension was sonicated to break up the agglomerates of silica spheres. Centrifugation at low speed was performed to remove larger particles from the suspension. The supernatant suspension was decanted and transferred to another centrifuge tube. Sonication was performed again and centrifugation at high speed to form synthetic opal. The ethanol was decanted and the synthetic opal was dried at room temperature. The dried synthetic opal was heated at 600°C for 4 hours to consolidate the opal. The heat treated opal chunks were infiltrated with titania as follows: The chunks were immersed in titanium isopropoxide for 4 hours and dried. The dried chunks were heated at 600°C for 1 hour. The titania infiltrated chunks were ground into powder. The titania infiltrated opal powders smaller than 63 μm were further ground in ethanol suspension to smaller particles. The particles were dried. 5 g of titania infiltrated opal powder was mixed with 45 g of glazing powder. The mixed powder was made into a paste and applied to the zirconia restoration. The glaze layer containing the opal particles was fired according to the firing schedule for the glaze.

[0064] Example 3: Dual titania infiltration of synthetic opals 7 g of silica spheres with a size of about 180 nm and 28 g of ethanol were added to a centrifuge tube to make a 20 wt% suspension of silica spheres in ethanol. The suspension was sonicated to break up the agglomerates of silica spheres. Centrifugation at low speed was performed to remove larger particles from the suspension. The supernatant suspension was decanted and transferred to another centrifuge tube. It was sonicated again and centrifuged at high speed to form synthetic opal. The ethanol was decanted and the synthetic opal was dried at room temperature. The dried synthetic opal was heated at 600°C for 4 hours to consolidate the opal. The heat treated opal chunks were infiltrated with titania as follows: The chunks were immersed in titanium isopropoxide for 4 hours and dried. The dried chunks were heated at 600°C for 1 hour. The titania infiltrated chunks were subjected to the titania infiltration process once again. The doubly infiltrated chunks were ground into powder. Opal powders smaller than 63 μm were further ground in an ethanol suspension to smaller particles. The particles were dried. 5 g of the dried titania doubly infiltrated opal powder was mixed with 45 g of glazing powder. The mixed powder was made into a paste and applied to the zirconia restoration. The glaze layer containing the opal particles was fired according to the firing schedule of the glaze.

[0065] Example 4: Dual titania infiltration of synthetic opals and hydrolysis of titania precursors prior to post-thermal treatment 7 g of silica spheres with a size of about 180 nm and 28 g of ethanol were added to a centrifuge tube to make a 20 wt% suspension of silica spheres in ethanol. The suspension was sonicated to break up the agglomerates of silica spheres. Centrifugation at low speed was performed to remove larger particles from the suspension. The supernatant suspension was decanted and transferred to another centrifuge tube. It was sonicated again and centrifuged at high speed to form synthetic opal. The ethanol was decanted and the synthetic opal was dried at room temperature. The dried synthetic opal was heated at 600°C for 4 hours to consolidate the opal. The heat-treated opal chunks were infiltrated with titania as follows: The chunks were immersed in titanium isopropoxide for 4 hours and dried. The dried chunks were soaked in water for 4 hours to hydrolyze the titanium isopropoxide and heated at 600°C for 1 hour. The titania infiltrated chunks were subjected to the titania infiltration and hydrolysis process once again. The doubly infiltrated chunks were ground to a powder. Opal powder smaller than 63 μm was further ground in an ethanol suspension to smaller particles. The particles were dried. 5 g of the dried opal powder doubly infiltrated with titania was mixed with 45 g of glazing powder. The mixed powder was made into a paste and applied to the zirconia restoration. The glaze layer containing the opal particles was fired according to the firing schedule for the glaze.

[0066] Example 5: 220 Milled Opal Powder with Dental Glazing Powder 7 g of silica spheres with a size of about 220 nm and 28 g of ethanol were added to a centrifuge tube to make a 20 wt% suspension of silica spheres in ethanol. The suspension was sonicated to break up the agglomerates of silica spheres. Centrifugation at low speed was performed to remove larger particles from the suspension. The supernatant suspension was decanted and transferred to another centrifuge tube. Sonication was performed again and centrifuged at high speed to form synthetic opal. The ethanol was decanted and the synthetic opal was dried at room temperature. The dried synthetic opal was heated at 600°C for 4 hours to consolidate the opal. The heat treated opal was crushed into powder. Opal powders smaller than 63 μm were further crushed into smaller particles in an ethanol suspension. The particles were dried. 5 g of opal powder was mixed with 45 g of glazing powder. The mixed powder was made into a paste and applied to the zirconia restoration. The glaze layer containing the opal particles was fired according to the firing schedule of the glaze.

[0067] Example 6: Titania penetration of synthetic opals - 220 nm 7 g of silica spheres with a size of about 220 nm and 28 g of ethanol were added to a centrifuge tube to make a 20 wt% suspension of silica spheres in ethanol. The suspension was sonicated to break up the agglomerates of silica spheres. Centrifugation at low speed was performed to remove larger particles from the suspension. The supernatant suspension was decanted and transferred to another centrifuge tube. Sonication was performed again and centrifugation at high speed to form synthetic opal. The ethanol was decanted and the synthetic opal was dried at room temperature. The dried synthetic opal was heated at 600°C for 4 hours to consolidate the opal. The heat treated opal chunks were infiltrated with titania as follows: The chunks were immersed in titanium isopropoxide for 4 hours and dried. The dried chunks were heated at 600°C for 1 hour. The titania infiltrated chunks were ground into powder. The titania infiltrated opal powders smaller than 63 μm were further ground in ethanol suspension to smaller particles. The particles were dried. 5 g of titania infiltrated opal powder was mixed with 45 g of glazing powder. The mixed powder was made into a paste and applied to the zirconia restoration. The glaze layer containing the opal particles was fired according to the firing schedule for the glaze.

[0068] Example 7: Dual titania penetration of synthetic opals - 220 nm 7 g of silica spheres with a size of about 220 nm and 28 g of ethanol were added to a centrifuge tube to make a 20 wt% suspension of silica spheres in ethanol. The suspension was sonicated to break up the agglomerates of silica spheres. Centrifugation at low speed was performed to remove larger particles from the suspension. The supernatant suspension was decanted and transferred to another centrifuge tube. It was sonicated again and centrifuged at high speed to form synthetic opal. The ethanol was decanted and the synthetic opal was dried at room temperature. The dried synthetic opal was heated at 600°C for 4 hours to consolidate the opal. The heat treated opal chunks were infiltrated with titania as follows: The chunks were immersed in titanium isopropoxide for 4 hours and dried. The dried chunks were heated at 600°C for 1 hour. The titania infiltrated chunks were subjected to the titania infiltration process once again. The doubly infiltrated chunks were ground into powder. Opal powders smaller than 63 μm were further ground in an ethanol suspension to smaller particles. The particles were dried. 5 g of the dried titania doubly infiltrated opal powder was mixed with 45 g of glazing powder. The mixed powder was made into a paste and applied to the zirconia restoration. The glaze layer containing the opal particles was fired according to the firing schedule of the glaze.

[0069] Example 8: Dual titania infiltration of synthetic opals and hydrolysis of titania precursors prior to post-heat treatment - 220 nm 7 g of silica spheres with a size of about 220 nm and 28 g of ethanol were added to a centrifuge tube to make a 20 wt% suspension of silica spheres in ethanol. The suspension was sonicated to break up the agglomerates of silica spheres. Centrifugation at low speed was performed to remove larger particles from the suspension. The supernatant suspension was decanted and transferred to another centrifuge tube. It was sonicated again and centrifuged at high speed to form synthetic opal. The ethanol was decanted and the synthetic opal was dried at room temperature. The dried synthetic opal was heated at 600°C for 4 hours to consolidate the opal. The heat-treated opal chunks were infiltrated with titania as follows: The chunks were immersed in titanium isopropoxide for 4 hours and dried. The dried chunks were immersed in water for 4 hours to titanium isopropoxide and heated at 600°C for 1 hour. The titania infiltrated chunks were once again subjected to the titania infiltration and hydrolysis process. The doubly infiltrated chunks were ground to a powder. Opal powder smaller than 63 μm was further ground in an ethanol suspension to smaller particles. The particles were dried. 5 g of the dried opal powder doubly infiltrated with titania was mixed with 45 g of glazing powder. The mixed powder was made into a paste and applied to the zirconia restoration. The glaze layer containing the opal particles was fired according to the firing schedule for the glaze.

[0070] The opals described above can be incorporated into dental products that are applied to restorations to achieve the desired aesthetics. In particular, these formulations can achieve the desired aesthetics at significantly thinner thicknesses than conventional materials.

[0071] Some embodiments provide a composition for imparting opalescence to a dental restoration, the composition comprising: about 50-85% by weight of a ceramic component; about 0-2% by weight of a viscosity modifier; about 2-15% by weight of an opal component; about 0-1% by weight of a fluorescent agent; and the balance a liquid component.

[0072] In some embodiments, the ceramic component is ceramic-based, present at about 50-85% by weight.

[0073] In some embodiments, the opal component is present at about 2-6% by weight.

[0074] In some embodiments, the opal component is present at about 6-12% by weight.

[0075] In some embodiments, the ceramic component is a glaze base present at about 50-65% by weight.

[0076] In some embodiments, the opal component is present at about 6-15% by weight.

[0077] In some embodiments, such dental products are structure-building compositions comprising: Approximately 50-85% by weight of base ceramic; about 0-2% by weight of a viscosity modifier; Approximately 2-12% opal by weight; Approximately 0-1% fluorescent agent; and the remaining liquid component.

[0078] In some embodiments, such dental products are structure-building compositions comprising: Approximately 50-85% by weight of base ceramic; about 0-2% by weight of a viscosity modifier; Approximately 2-6% by weight of opal; approximately 0-1% of fluorescent agent; and the remaining liquid component.

[0079] Other embodiments are traditional glazes that do not add substantial structure, such dental products include: Approximately 50-85% by weight of glaze base; about 0-2% by weight of a viscosity modifier; Approximately 6-16% opal by weight; Approximately 0-1% fluorescent agent; and the remaining liquid component.

[0080] The base ceramic is an unpigmented, unopacified dental porcelain of a firing temperature appropriate for the system being used. It is consistent with the dental matrix described above.

[0081] The glaze base is an unpigmented, transparent glazing porcelain with a firing temperature appropriate to the system being used. It is consistent with the glazes described above.

[0082] The viscosity modifier is any thickening agent suitable for use in the system being used. A viscosity modifier can be optionally added to control the consistency of the paste. The addition of the viscosity modifier aids in the formation of the paste and helps impart flow properties such as shear thinning, thixotropy, and / or shear thinning, if desired. The viscosity modifier can be selected from one or more of precipitated silica, fumed silica, polyethylene glycol, polyacrylic acid, salts of polyacrylic acid, polyvinyl alcohol, gums, saccharides, and organosilicones.

[0083] Opal component refers to synthetic opals as described herein.

[0084] The liquid component provides a vehicle for the glaze base and is removed during the baking process. Suitable liquid components include at least one liquid selected from C1-C6 monoalcohols, C1-C6 diols, C1-C6 triols, tripropylene glycol, polyethylene glycol, polypropylene glycol, and water.

Claims

1. A dental material, One or more dental matrices made of one or more dental ceramics, One or more colloidally assembled photonic crystals, wherein the colloidally assembled photonic crystals are colloidally assembled silica synthetic opals partially or completely permeated with one or more ceramics, and Contains liquid components, A dental material wherein the silica-synthetic opal is present in an amount of approximately 1 to 20% by weight of the dental material.

2. The dental material according to claim 1, wherein the dental ceramic comprises at least one of alumina, zirconia, glass ceramic, leucite-reinforced glass, glass-impregnated ceramic, and mixtures or solid solutions of two or more of these.

3. The dental material according to claim 1, wherein the penetrating ceramic material comprises one or more of the following: alumina, zirconia, titania, yttria, zinc oxide, hafnia, tin oxide, indium oxide, ceria, niobium oxide, tantalum oxide, germanium oxide, gallium oxide, and scandium oxide.

4. The dental material according to claim 1, wherein the penetrating ceramic material comprises one or more materials that can be converted to alumina, zirconia, titania, yttria, zinc oxide, hafnia, tin oxide, indium oxide, ceria, niobium oxide, tantalum oxide, germanium oxide, gallium oxide, scandium oxide, or mixtures or solid solutions of two or more thereof by chemical, thermal, light, pressure treatment, or a combination of two or more treatments.

5. A method for manufacturing dental materials, Assembling silica-synthetic opal, partially or completely impregnated with one or more ceramics, into a colloidal structure. A method comprising bonding one or more colloidally assembled silica synthetic opals with one or more dental materials comprising one or more dental ceramics and a liquid component, wherein the silica synthetic opal is present in an amount of about 1 to 20% by weight of the dental material.

6. The method according to claim 5, wherein the dental ceramic comprises at least one of alumina, zirconia, glass ceramic, leucite-reinforced glass, glass-impregnated ceramic, and mixtures or solid solutions of two or more thereof.

7. The method according to claim 5, wherein the penetrating ceramic material comprises one or more of the following: alumina, zirconia, titania, yttria, zinc oxide, hafnia, tin oxide, indium oxide, ceria, niobium oxide, tantalum oxide, germanium oxide, gallium oxide, and scandium oxide.

8. The method according to claim 5, wherein the penetrating ceramic material comprises one or more materials that can be converted by chemical, thermal, optical, pressure treatment, or a combination of two or more treatments, to alumina, zirconia, titania, yttria, zinc oxide, hafnia, tin oxide, indium oxide, ceria, niobium oxide, tantalum oxide, germanium oxide, gallium oxide, scandium oxide, or mixtures or solid solutions of two or more thereof.

9. The dental material according to claim 1, wherein the weight ratio of one or more colloidally assembled photonic crystals to one or more dental matrices is about 1:2 to about 1:

49.

10. The dental material according to claim 1, wherein the silica synthetic opal is present in an amount of about 2 to 6% by weight of the dental material.

11. The dental material according to claim 1, wherein the silica synthetic opal is present in an amount of about 6 to 12% by weight of the dental material.

12. The method according to claim 5, wherein the weight ratio of one or more colloidally assembled photonic crystals to one or more dental matrices is about 1:2 to about 1:

49.

13. The method according to claim 5, wherein the silica synthetic opal is present in the dental material in an amount of about 2 to 6% by weight.

14. The method according to claim 5, wherein the silica synthetic opal is present in the dental material in an amount of about 6 to 12% by weight.

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