Method for preparing multicolored dental restorations - Patent application

Abstract

A method for preparing a multicolored dental restoration is described, in which glasses and glass-ceramics having different compositions are given the shape of the dental restoration, and in which a color change is achieved in the glasses and glass-ceramics by irradiating them with artificial electromagnetic radiation and subjecting them to a heat treatment. The method for preparing a multicolored dental restoration according to the invention is characterized in that a) a glass or glass-ceramic is given the shape of the dental restoration, and b) a color change is achieved in at least a portion of the glass or glass-ceramic by irradiating this portion with artificial electromagnetic radiation and subjecting this irradiated portion to a heat treatment.

Description

[Technical Field]

[0001] The present invention relates to a method for preparing multicolored dental restorations in which color variations are achieved in glass or glass-ceramics. [Background technology]

[0002] Glass-ceramics, such as lithium silicate glass-ceramics, are typically characterized by very good mechanical properties and are therefore widely used as materials for preparing dental restorations.

[0003] To produce dental restorations from glass ceramics, various molding methods are used, such as pressing processes, sintering, or machining. Molding using CAD / CAM processes has proven particularly advantageous, in which a digital model of the desired dental restoration is first created in a computer-aided process (computer-aided design). The desired dental restoration is then typically manufactured based on this model by machining, particularly by milling and grinding, in a similar computer-aided process (computer-aided manufacturing).

[0004] Glass ceramics are also generally suitable for producing dental restorations due to their advantageous optical properties, such as high translucency.

[0005] Typically, a dentist or dental technician selects the appropriate color and translucency for a patient from a stock of blanks. However, it is not possible for a dentist or dental technician to keep blanks available for all naturally occurring color values ​​and translucency grades. However, a wide range of choices should be available to keep the color and translucency deviations between natural teeth and dental restorations small.

[0006] However, natural teeth have complex coloring with color gradients and 3D color effects. In order to make dental restorations in a patient's dentition indistinguishable from the surrounding natural tooth material, it is necessary to imitate the complex coloring of natural teeth as realistically and individually as possible, particularly in the area of ​​the anterior teeth.

[0007] For example, monochromatic dental restorations can be given the desired optical properties by subsequent veneer application. For example, using the cutback technique, a body having the shape of a natural dentin core can first be milled from a complete anatomical crown. If necessary, layers of differently colored materials, which usually also have higher translucency, can be applied to a body that usually has low translucency. In this way, dental restorations that meet high aesthetic demands can be obtained. However, the drawback is that this method is very complicated, and the results are highly dependent on the skills of the dental technician. It would be desirable to provide a simpler coloring process that allows for the individual coloring of dental restorations to meet high aesthetic demands. Furthermore, the method should be quick and efficient to perform, be amenable to automation, and the results should be less dependent on the technical skills of the dental technician than with currently used methods.

[0008] It is also possible to paint monochromatic dental restorations so that the coloring resembles natural teeth. Like the cut-back technique, the results of this method are highly dependent on the skill of the dental technician. Another drawback is that a 3D color effect cannot usually be achieved when a dental restoration is painted, since the color is only applied to the surface of the restoration. The typical translucency gradient of natural teeth cannot be imitated by painting either. For these reasons, the aesthetic results of painted dental restorations are usually not satisfactory, especially for those to be used in the anterior region.

[0009] In light of the above-mentioned difficulties, various methods have been developed for preparing multicolored dental restorations with realistic coloring.

[0010] EP 1 900 341 A1 describes a multicolored molding made of variously colored layers, in which the color transition between the layers is imperceptible. The multicolored molding, from which multicolored dental restorations can be manufactured using a CAD / CAM process, is produced by dry pressing, debonding, and sintering correspondingly colored glass ceramic powders layered on top of each other. However, to produce individually colored dental restorations, the individually layered moldings must be produced in a complex manner.

[0011] A method is known from EP 3 178 462 A1 for producing multicolored ceramic dental restorations, in which a porous ceramic body is first loaded with a color pigment solution, and then the color pigment is dispersed non-uniformly within the ceramic by controlling one or more environmental parameters, such as humidity and / or pressure. The dental ceramic blanks produced are particularly suitable for processing using CAD / CAM.

[0012] WO 2013 / 122662 describes individually colored milling blocks for dental use and methods for preparing them. The milling blocks are produced in a rapid prototyping process based on the coloring desired for the dental restoration to be created. For example, materials that can be subjected to a hardening step by polymerization are built up in layers to form milling blocks, where each layer can be individually colored in the desired areas. The materials preferably used are typically based on (meth)acrylate composites and do not have the advantageous mechanical properties of lithium silicate glass ceramics. EP 0 153 026 A1, DE 10 2005 003 595 A1, DE 103 04 382 A1, and US Patent Application Publication No. 2016 / 0340228 A1 describe methods for preparing glasses and glass ceramics for use as optical components, such as optical waveguides. In particular, they disclose that the treatment of glass with light and heat is suitable for changing the refractive index of the glass or for forming crystalline nuclei within the glass. However, coloring, which is undesirable for the use of materials as optical waveguides, has also been observed. There is no indication that these methods can produce products that can meet the extremely high demands on optical and mechanical properties used in the dental field. [Prior art documents] [Patent documents]

[0013] [Patent Document 1] International Application No. 2013 / 122662 [Patent Document 2] European Patent Application Publication No. 0153026 Summary of the Invention [Means for solving the problem]

[0014] Starting from the above-mentioned drawbacks of known methods, the object of the present invention is to provide a method for preparing multicolored dental restorations that can achieve coloration in a simple manner. Furthermore, the method should be suitable for preparing individually colored dental restorations, where color variation is achieved in a controlled manner in the materials used, so that the prepared dental restorations have color gradations that model the color gradations of natural tooth materials. The method should be capable of being automated and, preferably, combined with an automated molding process. Multicolored dental restorations prepared using this method should also have advantageous translucency and advantageous mechanical properties, such as high strength and fracture toughness, and should also be chemically resistant and biocompatible.

[0015] This object is achieved by the methods according to claims 1 to 24. The invention is also directed to polychromatic dental restorations according to claim 25 and to uses according to claims 26 and 27.

[0016] The method for preparing a multicolored dental restoration according to the present invention comprises: a) giving the glass or glass ceramic the shape of the dental restoration; b) a color change is achieved in at least a portion of the glass or glass ceramic by irradiating said portion with artificial electromagnetic radiation and subjecting said irradiated portion to a heat treatment. It is characterized by:

[0017] Surprisingly, the method according to the present invention has been shown to enable the simple preparation of multicolored dental restorations, and polychromatism can be achieved in a targeted manner in glasses or glass ceramics, such as lithium silicate glasses or lithium silicate glass ceramics. Furthermore, it has been surprisingly found that continuous color gradations can be produced. Unlike many conventional methods, the application of coloring materials does not cause a color change, but the color change is achieved in glasses and glass ceramics, so even 3D color gradations can be realized.

[0018] Furthermore, the method surprisingly allows for easy color selection and coloring, which can also be automated and adapted to individual needs. Known automated processes for molding, such as CAD / CAM processes, can be included, thereby realizing comprehensive digitalization of the design and preparation of individually molded and individually colored dental restorations. Compared to traditional methods, such as painting or cutting back processes for dental restorations, such advanced digitalization and automation allows for quick and precise preparation, and the aesthetics of the result are less dependent on the technical skills of the person performing the preparation.

[0019] This method is also advantageous for dentists or dental technicians in terms of the storage and logistics of starting materials. According to the present invention, the desired coloring of a dental restoration can be achieved from several different starting materials, particularly from several types of blanks. Therefore, it is no longer necessary for dentists or dental technicians to maintain blanks or raw materials available in many commercially available color values ​​and translucency grades, or to order them as needed. Instead, maintaining blanks with only one color value available in various translucency grades may be sufficient for the dentist's or dental technician's usual needs. DETAILED DESCRIPTION OF THE INVENTION

[0020] A "color change" is achieved according to the present invention if, after step b) has been performed, the irradiated and heat-treated portion of the glass or glass-ceramic differs in at least one of color value, lightness, and translucency from the portion before step b) has been performed, preferably in at least one of color value and lightness. The terms "color" and "colored" therefore relate to the color value, lightness, and translucency of the material.

[0021] The color value and lightness are determined in particular in accordance with DIN 6174. * a * The color can be characterized by the b-value or by a shade guide commonly used in the dental industry. Color measurements can be performed with a commonly used measuring device, such as the CM-3700d spectrophotometer (Konica Minolta). Examples of shade guides are the Vitapan classical® and Vita 3D Master®, both manufactured by VITA Zahnfabrik H. Rauter GmbH & Co. KG, and the Chromascop® manufactured by Ivoclar Vivadent AG.

[0022] The term "translucency" is the light transmission of a material, i.e. the ratio of the intensity of transmitted light to the intensity of incident light. Translucency can be determined in the form of a contrast value (CR value) according to British Standard 5612.

[0023] Virtually any color desired for the preparation of dental restorations can be achieved by the method of the present invention. In particular, the desired yellow shade (b * value) and red tint (a * Values) can be achieved in a controlled manner. Methods for determining the desired material color in the preparation of dental restorations are known in the state of the art, for example from WO 2018 / 162671.

[0024] The color achieved by the color change according to step b) has a b value of at least 4.00 as determined according to DIN 6174. * value and a of at least -1.00 * Furthermore, the color achieved by the color change preferably has a b value of 40.00 or less, as determined in accordance with DIN 6174. * Value and a below 25.00 * It is preferred that the value

[0025] In a preferred embodiment, the red coloration is achieved in at least one portion of the glass or glass-ceramic and the yellow coloration is achieved in at least one other portion of the glass or glass-ceramic.

[0026] It is further possible to combine the color change according to step b) of the method according to the invention with other coloring processes for preparing dental restorations, such as ionic coloring or the use of color pigments.

[0027] It is particularly preferred that the glasses and glass ceramics used in the process according to the invention comprise at least one oxidizing component and at least one reducing, coloring component.

[0028] The term "oxidizing component" refers to a component that can be oxidized by irradiation of the glass or glass ceramic in step b). Preferred oxidizing components are cerium ions, europium ions, erbium ions, copper ions, and mixtures thereof, in particular cerium ions. Ce 3+ is a particularly preferred oxidizing component.

[0029] In a preferred embodiment of the method according to the invention, the glasses and glass ceramics contain Ce, calculated as CeO, preferably in an amount of 0.01 to 1.5, in particular 0.03 to 1 wt. %. According to the invention, "Ce" denotes cerium in all oxidation states present in the glasses and glass ceramics.

[0030] Ce can be detected using UV / visible spectroscopy. 3+ The content of Ce in glass and glass ceramics can be determined using fluorescence spectroscopy. 4+ The Ce content is determined by the amount of Ce used in glass formation. 3+ The content can be taken into consideration when making the determination.

[0031] The term "reducible coloring component" refers to a component that can be reduced with a change in color. Preferred reducible coloring components are metal cations, such as Ag, Au, Cu, or combinations thereof, with Ag and / or Au cations being particularly preferred.

[0032] Metals such as Ag and Au can be present in glasses and glass ceramics in various oxidation states. Without further specification, according to the present invention, the terms "Ag" and "Au" refer to all oxidation states of these metals in glasses and glass ceramics, preferably to oxidation states 0 and 1.

[0033] In a preferred embodiment of the method according to the invention, the glasses and glass ceramics contain Ag, calculated as Ag2O, preferably in an amount of 0.0005 to 1.3, in particular 0.002 to 0.7% by weight.

[0034] In another preferred embodiment, the glasses and glass ceramics contain 0.0001 to 0.65, in particular 0.0003 to 0.25, particularly preferably 0.003 to 0.2% by weight of Au, calculated as AuO.

[0035] In a particularly preferred embodiment of the method according to the invention, the glasses and glass ceramics comprise Ce and Ag and / or Au.

[0036] When Ce and Ag are present in the glass and glass ceramic, particularly yellow coloring can be achieved in step b).When Ce and Au are present in the glass and glass ceramic, particularly red coloring can be achieved in step b).When Ce, Ag, and Au are present in the glass and glass ceramic, particularly yellow coloring and red coloring can be achieved in step b).

[0037] The amount of Ce, Ag, and Au in the glass and glass-ceramic, especially the amount of Ag and Au, can affect the color achieved by the color change. It has been found that more intense colors can usually be achieved through the use of higher amounts of Ag and / or Au.

[0038] Without being limited to one theory, it is assumed that the irradiation in step b) enables a redox reaction that can oxidize the oxidizable component and reduce the reducible coloring component. For example, when Ce and Ag are present in glass and glass-ceramics, electromagnetic radiation is assumed to enable the reaction according to the following equation: Ce 3+ +Ag + →Ce 4+ +Ag 0

[0039] It has been shown that heat treatment of the irradiated glass or glass-ceramic from step b) can lead to the formation of particles with reduced coloring components or to the accumulation of already existing such particles. These particles, which can exist in particular as "clusters" or "colloids," can contribute to the color of the glass and glass-ceramic. Such particles can be detected, for example, using transmission electron microscopy (TEM).

[0040] For example, it has been found that in glasses and glass-ceramics, particles bearing Ag typically achieve a yellow coloration, and particles bearing Au typically achieve a red coloration.

[0041] In other preferred embodiments, the glasses and glass-ceramics in which a color change is achieved in step b) contain Ag halides, such as AgCl, AgBr, and / or AgI. Such Ag halides can generally be detected qualitatively, for example, using NMR spectroscopy, transmission electron microscopy, or Raman spectroscopy.

[0042] In a preferred embodiment, the glasses and glass ceramics contain Cl, Br, and / or I, especially Cl, in an amount of 0.0001 to 0.9, particularly preferably 0.0005 to 0.7 wt. %. Typically, Cl, Br, and I are present in the glasses and glass ceramics in ionic form, preferably in the oxidation state −1. These halides are usually derived from the halides used as starting materials, such as Ag or Cu halides.

[0043] In other preferred embodiments, the glasses and glass-ceramics in which the color change is achieved in step b) contain 0.01 to 1.5 wt. % Ce, calculated as CeO, 0.0005 to 1.3 wt. % Ag, calculated as AgO, 0.06 to 0.5 wt. % Sb, calculated as SbO, and 0.01 to 0.15 wt. % Sn, calculated as SnO. This preferred glass and this preferred glass-ceramic can impart yellow and red coloring, with a higher Sb content typically achieving a stronger red coloring.

[0044] To achieve the color change, the glasses and glass ceramics are first irradiated in step b) with artificial electromagnetic radiation, where "artificial electromagnetic radiation" means, according to the invention, radiation emitted by an artificial radiation source.

[0045] The radiation irradiated onto the glass and glass ceramic can comprise portions with different wavelengths. If only a portion of the total radiation is suitable to bring about a color change, this is sufficient for the method according to the invention.

[0046] In a preferred embodiment, the glass and glass ceramic are irradiated with X-rays. The X-ray source used preferably has an anode material selected from the group consisting of Cu, Co, Cr, Fe, or Mo, in particular Cu. The irradiation can be achieved with X-ray energies of various spectral lines. The irradiation is preferably achieved with Kα radiation.

[0047] In another preferred embodiment, the glasses and glass-ceramics are irradiated with UV radiation. According to the present invention, "UV radiation" denotes electromagnetic radiation having a wavelength of 100 to 400 nm.

[0048] In a particularly preferred embodiment, the radiation has a wavelength of 380 nm or less, in particular in the range from 100 to 360 nm, particularly preferably in the range from 250 to 350 nm, most preferably in the range from 300 to 310 nm.

[0049] The radiation was determined as spectrally weighted irradiance according to DIN EN 62471:2009-03 at a distance of 20 cm from the radiation source, in the wavelength range from 180 to 400 nm, of 1 mW / m 2 greater than 3 mW / m 2 more preferably 10 mW / m 2 greater than 100 mW / m 2 It is particularly preferred that the radiation be emitted by a radiation source having an effective irradiance greater than .

[0050] Preferably, a UV LED, a UV laser, an X-ray diffractometer or a mercury vapor lamp is used as the radiation source in step b).

[0051] In a preferred embodiment, the wavelength of the radiation is matched to the oxidizing components present in the glass and glass ceramic. For example, a wavelength in the region of about 310 nm has been shown to be advantageous when cerium ions are present in the glass and glass ceramic, while a wavelength of about 280 nm is advantageous when copper ions are present.

[0052] It has been found that the color change achieved according to step b) generally depends on the conditions of irradiation, in particular the duration of irradiation, the irradiance, and the wavelength of the radiation, and in particular it has been found that more intense colors can typically be achieved with higher irradiances or longer irradiation durations.

[0053] In some embodiments, the entire glass or glass-ceramic is irradiated in step b). To achieve polychromatism, different regions are typically irradiated under different conditions.

[0054] In a preferred embodiment, only a portion of the glass or glass ceramic is irradiated in step b). Although partial irradiation already imparts polychromatism to the glass or glass ceramic, different regions can also be irradiated under different conditions.

[0055] In the irradiation of glasses and glass ceramics, a small beam diameter can be advantageous for limiting the color change to a small area of ​​the glass or glass ceramic and thus closely mimicking the fine color gradations of natural tooth materials, while a large beam diameter can be advantageous for uniform irradiation of the glass or glass ceramic and can contribute to keeping the time required for the method short.

[0056] In a preferred embodiment, the radiation has a defined local focus. This focus can particularly preferably be directed to regions of the glass or glass ceramic that are not on the surface of the glass or glass ceramic. By focusing the radiation or by using several beam paths with defined focuses, it is possible to achieve a color change preferentially in the focused region in the glass or glass ceramic, while not achieving or hardly achieving any color change along the beam paths in the glass or glass ceramic.

[0057] A mold can be used during the irradiation of step b) to limit the irradiation to specific areas of the glass and glass ceramic and / or to attenuate the radiation.

[0058] To achieve the color change, at least one irradiated portion of the glass or glass ceramic is heat-treated in step b) of the method according to the invention. The heat treatment is preferably effected at a temperature in the range of 300 to 1000°C, in particular 400 to 950°C, particularly preferably 450 to 850°C.

[0059] In a preferred embodiment, the heat treatment is effected for a duration of up to 120 minutes, in particular up to 60 minutes.

[0060] It has been shown that the color achieved in the color change according to step b) generally depends on the conditions of the heat treatment. For example, it has been established that stronger and / or darker colors can usually be achieved using higher temperatures or longer durations. The temperature and duration required to achieve a particular color change usually interact with each other. In general, the duration to achieve a particular color change can be shortened at higher temperatures, and vice versa.

[0061] Glasses and glass ceramics are typically subjected to the heat treatment of step b) in a furnace. Suitable furnaces are, for example, furnaces of the Programat type manufactured by Ivoclar Vivadent AG.

[0062] In another preferred embodiment, the heat treatment in step b) is achieved with a laser, such as a UV laser, a VIS laser, or an IR laser, in particular an IR laser generating radiation with a wavelength greater than 5 μm, or a VIS laser generating radiation with a wavelength of 500 to 600 nm, particularly preferably 515 to 532 nm. The laser parameters (wavelength, pulse duration, pulse energy, continuous wave operation) are typically selected so that the glasses and glass ceramics are heated to the temperature required for the color change, but without evaporating or damaging them.

[0063] Laser heat treatment of glasses and glass ceramics is typically achieved only in selected regions of the glass or glass ceramic, thereby limiting the color change to selected regions, or different regions of the glass or glass ceramic can be subjected to heat treatment to different degrees. Laser heat treatment can be particularly advantageous for achieving complex three-dimensional color gradations or for changing the translucency of a material.

[0064] In a preferred embodiment, the heat treatment of the irradiated glass and irradiated glass ceramic in step b) also achieves crystallization of the glass or further crystallization of the glass ceramic, for example, of lithium metasilicate and / or lithium disilicate, and thus the overall duration of the method for preparing a dental restoration can be advantageously shortened.

[0065] In other embodiments, the heat treatment of step b) is accomplished in addition to the heat treatment carried out to form the desired crystals.

[0066] The irradiation and heat treatment of step b) can be carried out in one step or in separate steps.

[0067] Irradiation and heat treatment are typically carried out in separate process steps, where the glasses and glass ceramics are irradiated with a first radiation source and the irradiated glasses and glass ceramics are subsequently subjected to heat treatment, in particular with the aid of a second radiation source or another device such as a furnace.

[0068] However, it may be advantageous to carry out irradiation and heat treatment in one step. In this case, irradiation and heat treatment can be achieved simultaneously by different devices. Preferably, a UV laser is used for irradiation, and a furnace, a VIS laser, or a UV laser is used for heat treatment. However, irradiation and heat treatment can also be carried out in one device. For this purpose, it is typically necessary to irradiate the glass and glass ceramic with a very high irradiance so that the heat generated by radiation in the glass and glass ceramic is sufficient to achieve a color change.

[0069] If the irradiation and heat treatment are accomplished in separate process steps, the heat treatment can be carried out immediately after the irradiation.

[0070] On the other hand, in another preferred embodiment, the heat treatment is carried out in a step that is not immediately after irradiation. The color change after step b) of the method according to the invention can also be achieved if the irradiated glass or irradiated glass ceramic is stored and subsequently subjected to heat treatment, for example, after several days or weeks.

[0071] In another embodiment, in at least a part of the glass ceramic, this part is heated to at least 150 °C, preferably from 150 to 800 °C, particularly from 200 to 800 °C, particularly preferably from 300 to 700 °C, and it is irradiated at this temperature, whereby a color change is achieved. This embodiment is particularly suitable for achieving yellow or red coloring in the glass ceramic.

[0072] When the irradiation and heat treatment for achieving the color change, particularly yellow coloring, are carried out simultaneously, the heat treatment can, surprisingly, be carried out at a lower temperature than in the embodiment where the irradiation and heat treatment are carried out one after another. Therefore, achieving the color change by irradiation and simultaneous heat treatment enables shorter heating and cooling times and can reduce the energy consumption of the process.

[0073] In at least a part of the glass ceramic, first this part is subjected to a first irradiation at temperature T1, then it is subjected to a first heat treatment at temperature T2, then this part or another part of the glass ceramic is subjected to a second irradiation at temperature T3 and simultaneously to a second heat treatment, whereby a color change is achieved, and an embodiment where T1 < T2 and T3 < T2, preferably T1 < T3 < T2, is particularly preferred.

[0074] Preferably, T1 is less than 300°C, in particular not more than 200°C, particularly preferably not more than 150°C. It is further preferred that T2 is greater than 700°C, in particular at least 800°C, particularly preferably at least 850°C. T3 is preferably greater than 150°C, in particular greater than 200°C, particularly preferably at least 300°C. Furthermore, T3 is preferably less than 850°C, in particular less than 800°C, particularly preferably not more than 700°C. Preferably, T3 is in the range of from 200 to 800°C, particularly preferably from 300 to 700°C.

[0075] In this embodiment, the first irradiation and first heat treatment can particularly achieve a red coloring of the glass ceramic. In particular, a subsequent second irradiation, together with a simultaneous second heat treatment, can achieve a yellow coloring. The first and second irradiations can be performed on the same and / or different parts of the glass ceramic. In this way, it is possible to prepare glass ceramics with red and yellow colorings, in which the coloring can be achieved individually in each case at selected locations. This can be advantageous in an efficient process in which, after the first heat treatment at a temperature of T2, the ceramic is cooled to a temperature of T3 and then directly subjected to the second irradiation and second heat treatment.

[0076] Glasses and glass-ceramics suitable for the process according to the invention are usually produced from corresponding mixtures of suitable starting materials such as carbonates, oxides, phosphates and halides.

[0077] Preferably, Ce oxide, Ce carbonate, Ce halide, Ce sulfate, and / or Ce phosphate are used as the Ce-containing raw material. In particularly preferred embodiments, CeO2, CeCl3, CeF3, CeI3, CeBr3, Ce2(SO4)3, or combinations thereof are used as the Ce-containing raw material.

[0078] Glasses and glass ceramics preferably contain P2O5 in an amount of 0.5 to 11.0 wt%, particularly preferably 0.9 to 10 wt%, particularly preferably 0.9 to 8.0 wt%, even more preferably 2.0 to 8.0 wt%, and even more preferably 2.0 to 6.0 wt%. The crystallization that transforms glass into glass ceramics with a nucleating agent such as P2O5 typically proceeds via the volume crystallization mechanism. Therefore, the nucleating agent present in the glass is preferably homogeneously distributed within the glass. Further possible nucleating agents are TiO2, ZrO2, Nb2O5, metals such as Pt, Pd, Ag, and Au, or mixtures thereof.

[0079] It is also preferred that the glasses and glass ceramics contain 0 to 14.0, in particular 1.0 to 14.0, preferably 2.0 to 12.0, particularly preferably 2.0 to 10.0 wt. % Al2O3. The glasses and glass-ceramics preferably contain at least one, and preferably all, of the following components in the amounts specified: [Table A] The glasses and glass ceramics particularly preferably comprise at least one, and preferably all, of the following components in the amounts specified: [Table B]

[0080] In some embodiments, the glasses and glass-ceramics may contain, in addition to LiO, further alkali metal oxides, such as Me. I 2O in an amount of 0 to 13.0, preferably 0 to 12.0, particularly preferably 1.0 to 11.0% by weight, I 2O is selected from K2O, Na2O, Rb2O, and / or Cs2O.

[0081] In a preferred embodiment, the glasses and glass ceramics contain 1.0 to 12.0, in particular 1.0 to 10.0, particularly preferably 2.0 to 8.0, wt. % K2O.

[0082] Furthermore, the glasses and glass ceramics may contain from 0 to 6.0, preferably from 0 to 5.0, wt. % of other oxides of divalent elements Me II Preferably it contains O, and Me II O is selected from MgO, CaO, SrO, and / or ZnO.

[0083] The glasses and glass ceramics may contain from 0 to 2.0, preferably from 0 to 1.0, weight percent of other oxides of trivalent elements Me III 2O3, and more preferably Me III 2O3 is selected from B2O3, Y2O3, La2O3, and / or Er2O3.

[0084] Furthermore, the glasses and glass ceramics may contain from 0 to 2.0 wt. %, preferably from 0 to 1.0 wt. %, of other oxides of tetravalent elements Me IV Preferably, it contains O2, and Me IV O2 is selected from SnO2, ZrO2, and / or GeO2.

[0085] Additionally, the glasses and glass ceramics may contain from 0 to 2.0 wt. %, preferably from 0 to 1.0 wt. %, of other pentavalent oxides Me V 2O5, and Me V 2O5 is selected from V2O5, Ta2O5, and / or Nb2O5.

[0086] The glasses and glass ceramics contain from 0 to 7.5, preferably from 0 to 6.5, by weight, of oxides of hexavalent elements Me VI It is also preferred to include O3, Me VI O3 is selected from MoO3 and / or WO3.

[0087] Some of the above-mentioned components can act as colorants and / or fluorescent agents. The glasses and glass-ceramics can also contain additional colorants and fluorescent agents, such as colored metal oxides and / or color-matching pigments as are customary in the trade.

[0088] Typically, to produce the glass, the corresponding mixture of suitable starting materials is melted, in particular at a temperature of 1000 to 1800°C, preferably about 1400 to 1650°C, for a duration of 0.5 to 10 hours, and then cooled.

[0089] To achieve high homogeneity, the resulting glass melt can be poured into water to form granular glass material, which can then be melted again, and the melt can be poured into a mold to form a glass blank, a so-called solid glass blank or monolithic blank.

[0090] Cooling can be carried out in a controlled manner to allow for the relaxation of stresses in the glass associated with rapid temperature changes and to prevent distortion in the structure. For this purpose, the melt is usually poured into a preheated mold, for example at a temperature of 400°C, or cooled slowly in a furnace.

[0091] In a preferred embodiment, the color change is achieved in a glass that is a monolithic glass blank or in a glass-ceramic prepared from a monolithic glass blank.

[0092] The glasses used in the method according to the invention may contain nuclei for the formation of crystalline phases, also called "nucleus-containing glasses", and are usually precursors of the corresponding glass-ceramics. For example, lithium silicate glasses may contain nuclei for the formation of lithium metasilicate and / or lithium disilicate crystals.

[0093] The glass-ceramics used according to the invention can be prepared from the resulting glasses using heat treatments, which typically involve several heat treatments for nucleation and crystallization.

[0094] Typically, for example, a first heat treatment is used to form crystalline nuclei suitable for forming lithium metasilicate crystals to prepare lithium silicate glass ceramics. A second heat treatment is typically used to crystallize the lithium metasilicate, and a third heat treatment is typically used to convert the lithium metasilicate to lithium disilicate. Several steps, such as the nucleation and crystallization of lithium metasilicate, can occur during a single heat treatment. Suitable conditions, particularly suitable temperature ranges, heating rates, and treatment durations, are known in the art, for example, from DE 103 36 913 A1, for preparing lithium silicate glass ceramics.

[0095] In a preferred embodiment, the glass and glass ceramic for which the color change is achieved consist of only one glass and one glass ceramic, respectively. This particularly means that there are no mixtures of different glasses or glass ceramics. Such mixtures can occur, for example, when preparing dental restorations from powder compacts formed from multiple glass or glass ceramic powders.

[0096] It is also preferred that the glasses and glass ceramics in which a color change is achieved in step b) are selected from the group consisting of lithium silicate glasses, lithium aluminosilicate glasses, lithium silicate glass ceramics, lithium aluminosilicate glass ceramics, and quartz glass ceramics.

[0097] The crystalline phases present in glass ceramics can be determined by X-ray diffraction analysis (XRD). The mass of the crystalline phases can be determined, in particular, using the Rietveld method. A suitable method is described, for example, in M. Dittmer's doctoral thesis "Glasses and Glass-Ceramics in the System MgO-Al2O3-SiO2 with ZrO2 as Nucleating Agent" (Glasses and Glass-Ceramics in the System MgO-Al2O3-SiO2 with ZrO2 as Nucleating Agent), University of Jena, 2011.

[0098] In a preferred embodiment of the method according to the invention, the glass-ceramic irradiated in step b) comprises lithium metasilicate, lithium disilicate, low-temperature quartz or lithium aluminosilicate, preferably lithium disilicate or low-temperature quartz, as the predominant crystalline phase.

[0099] The term "predominant crystalline phase" refers to the crystalline phase that has the highest proportion by mass among all crystalline phases present in the glass-ceramic.

[0100] In a preferred embodiment, the glass ceramic comprises more than 5% by weight, preferably more than 10% by weight, particularly preferably more than 20% by weight, of lithium metasilicate relative to the total glass ceramic.

[0101] In another preferred embodiment, the glass ceramic comprises more than 10% by weight, preferably more than 30% by weight, particularly preferably more than 50% by weight, of lithium disilicate relative to the total glass ceramic.

[0102] In other preferred embodiments, the ceramic comprises lithium disilicate as the predominant crystalline phase and low-temperature quartz as the other crystalline phase, or low-temperature quartz as the predominant crystalline phase and lithium disilicate as the other crystalline phase.

[0103] In a preferred embodiment of the method according to the invention, the glass-ceramic irradiated in step b) comprises, in addition to lithium metasilicate and / or lithium disilicate, one or more other crystalline phases selected from lithium aluminosilicate, lithium orthophosphate, apatite, low-temperature quartz, cristobalite, diopside, wollastonite, scheelite and powellite, particularly preferably low-temperature quartz and / or lithium aluminosilicate.

[0104] In step a) of the method according to the invention, the glass and glass ceramic are given the shape of the desired dental restoration. It is particularly preferred that the glass and glass ceramic are given the shape of the dental restoration in step a) by pressing or machining.

[0105] Forming can involve pressing glasses and glass ceramics at high temperatures and pressures, for example in the form of a partially pre-sintered lithium silicate blank, to obtain the desired shape. During pressing, the materials used are transformed into a viscous state so that they can flow under the influence of high pressure into the desired shape.

[0106] In a preferred embodiment, the shaping in step a) is achieved by machining. Machining is typically achieved by material removal processes such as milling and grinding. Glass ceramics, particularly lithium silicate glass ceramics, containing lithium metasilicate or lithium disilicate, particularly preferably containing lithium metasilicate as the main crystalline phase, are preferably used for machining. The use of lithium silicate glass ceramics that are not primarily crystallized to form lithium disilicate offers the advantage of simpler machining and less mechanical wear. After machining such partially crystallized materials, the latter are typically subjected to heat treatment to achieve further crystallization, preferably to form lithium disilicate.

[0107] The machining is preferably accomplished by a CAD / CAM process. Glass ceramics, such as lithium silicate glass ceramics, can be used, especially in the form of blanks. The shape of these blanks can be adapted to the type of machine used for machining.

[0108] In another preferred embodiment of the method, the color change step is combined with a CAD / CAM process. Therefore, the method according to the present invention includes a process in which information about the color design of the dentition is further recorded and processed in the CAD step. Based on a 3D model that also takes into account the processed color information, a dental restoration can be modeled that has not only the desired shape but also the desired color design. The dental restoration can be manufactured based on this model in the CAM step. Glass and glass ceramic, preferably in the form of a blank, are typically shaped by machining, irradiated according to step b), and subjected to heat treatment. Irradiation is preferably achieved in areas that already have the shape of the desired dental restoration. However, it may also be desirable to perform machining for shaping after the color change has been achieved according to step b).

[0109] Dental restorations with individual shapes and individual colorings can therefore be produced in an automated process. Such CAD / CAM processes with coloring are very attractive because they allow the desired dental restoration to be quickly provided to the patient. Strictly speaking, as in the case of conventional CAD / CAM processes, the dentist can perform so-called chairside procedures.

[0110] In a particularly preferred embodiment of the method according to the invention, the dental restoration is a bridge, an inlay, an onlay, a veneer, an abutment, a partial crown, a crown, or a shell.

[0111] Steps a) and b) of the method according to the invention can be carried out in any desired order. The method can further comprise several shaping steps and / or several color change steps.

[0112] In embodiments, the glasses and glass-ceramics are given the shape of the desired dental restoration before or after irradiation or before or after heat treatment.

[0113] In other embodiments, the glasses and glass-ceramics are given the shape of the desired dental restoration during the irradiation and heat treatment steps necessary for the color change.

[0114] The present invention further relates to a multicolored dental restoration obtainable by the method according to the invention described above.

[0115] Multicolored dental restorations prepared by the method according to the invention are typically characterized by a substantially continuous color gradation, i.e., a color gradation with spatial resolution in the micrometer or nanometer range, whereas multicolored dental restorations prepared by conventional methods according to the prior art typically have differently pigmented color layers with layer thicknesses in the millimeter range.

[0116] Multicolored dental restorations prepared by the method according to the invention generally have advantageous mechanical properties. A high lithium disilicate content in the prepared dental restorations is usually desirable due to superior mechanical properties, such as high strength.

[0117] In a preferred embodiment, the dental restorations prepared by the method according to the invention have a biaxial strength of at least 200 MPa, in particular at least 250 MPa, particularly preferably at least 300 MPa, and / or at least 1.5 MPa m 0.5 It has a fracture toughness of

[0118] In a preferred embodiment, the glass and glass ceramic of the dental restoration in which a color change is achieved consist of only one glass and only one glass ceramic, respectively, which means that there are in particular no mixtures of different glasses or glass ceramics in the dental restoration.

[0119] Dental restorations prepared by the method according to the invention preferably have an acid solubility of 100 μg / cm according to ISO 6872 2 Less than 50 μg / cm 2It has high chemical resistance, less than

[0120] The present invention also relates to the use of a glass or glass ceramic as a dental material, in particular for preparing a polychromatic dental restoration, in which a color change is achieved in at least a part of the glass or glass ceramic by irradiating said part with artificial electromagnetic radiation and subjecting said irradiated part to a heat treatment.

[0121] In particular, the present invention also relates to the use of glasses or glass ceramics as dental materials, in which the glasses and glass ceramics are subjected to the above-mentioned method. All glasses and glass ceramics described in relation to the method according to the present invention are also suitable for the use of glasses or glass ceramics according to the present invention. All process steps and process parameters described in relation to the method according to the present invention can also be performed and selected in the use according to the present invention.

[0122] The present invention will now be described in more detail with reference to examples. [Example]

[0123] Glasses with the chemical compositions specified in Tables 1 to 5A were prepared. For this purpose, the corresponding batches of raw materials, such as oxides, carbonates, phosphates, and halides, were melted at melting temperatures (T) between 1000 and 1650°C. s ) and melting duration (t s ), the glass melt was prepared over two melting temperatures (T S1 , T S2 ) and two melting durations (t s1 , t s2 ) was carried out in a two-step process.

[0124] The components of the glasses and glass-ceramics are calculated as oxides, as is customary for glasses and glass-ceramics, unless otherwise indicated.

[0125] Polychrome dental restorations were prepared from glasses using the process according to the invention and the conditions specified in Tables 6 to 16 were used for irradiation and heat treatment. In Tables 6 to 16 the following meanings apply: T g glass transition temperature, T s melting temperature, t s Melting duration, T N nucleation temperature, t N nucleation duration, QT mercury vapor lamp, TQ 150 type high pressure Hg lamp (Heraeus, Hanau, Germany), LED light source, model LCS-0310-03-23 ​​(Mightex Systems, Ontario, Canada) or model M300L4 (ThorLabs Inc., NJ, USA), σ B Biaxial strength, determined by ISO 6872 (2008).

[0126] The process steps shown in Tables 6 through 16 are listed in their chronological order, with the process steps listed at the top of each table occurring earlier than the process steps listed further down.

[0127] A Programat type furnace manufactured by Ivoclar Vivadent AG was used for all heat treatments given in the examples.

[0128] The crystalline phase of the glass-ceramic was determined using X-ray diffraction analysis.

[0129] The color value of the produced glass-ceramic (L * a * b) was determined using a CM-3700d spectrophotometer (Konica-Minolta) in the measurement range of 400–700 nm. The CR value (transparency) was determined according to British Standard BS 5612. [Table 1] [Table 2] [Table 3] [Table 4] [Table 5] [Table 5A]

[0130] (Examples 1 to 8) Color changes in glass due to mercury vapor lamp irradiation and heat treatment. Heat treatment for the formation of crystal nuclei was first carried out on the lithium silicate glasses of Examples 1 to 5. The nucleus-containing glasses were then subjected to irradiation for 15 to 60 minutes with a mercury vapor lamp (TQ150 type high-pressure Hg lamp, Heraeus, Hanau, Germany) and heat treatment for 15 to 60 minutes at 470 to 610°C. The conditions used in each case, the color achieved by irradiation and heat treatment, and the determined crystalline phase of the resulting glass-ceramic are specified in Table 6. A nucleation duration of 0 minutes means that the glass, after pouring, is transferred into a furnace set at the nucleation temperature and cooled there without a holding time.

[0131] After irradiation of the nucleus-containing glasses and subsequent heat treatment, yellow and red colorings were found in the glass-ceramics. Furthermore, it was observed that, for example, in the glass-ceramics of Examples 1 and 2, longer irradiation resulted in stronger and darker colorings.

[0132] It can also be seen from a comparison of Examples 3 to 5 that the color achieved by the color change depends on the temperature of the heat treatment. The heat treatment of Example 4, which was achieved at a higher temperature compared to Examples 3 and 5, resulted in a stronger and darker coloration in the glass-ceramic than in the glass-ceramics of Examples 3 and 5.

[0133] A decrease in translucency was observed in the glass-ceramic of Example 4 after irradiation and heat treatment.

[0134] From a comparison of the colors of the irradiated and heat-treated areas of the glass-ceramics of Examples 6 and 8, it is clear that stronger and darker colors could be achieved with longer irradiation.

[0135] The glass-ceramics prepared in Examples 1 to 5 contained 0.12 wt. % AgO, compared to 0.25 wt. % AgO present in the glass-ceramics of Examples 6 to 8. The colors produced in the glass-ceramics of Examples 2 and 6 demonstrate that more intense colors can be achieved when the glass or glass-ceramic contains higher amounts of Ag.

[0136] The color change was achieved in the glass and glass ceramic of Example 7 in two steps, each involving one irradiation and one heat treatment. The first color change involved irradiating the nucleus-containing glass with a mercury vapor lamp and heat treating it. The heat treatment for the first color change also resulted in crystallization of the nucleus-containing glass. The glass ceramic formed in this process was again irradiated with an LED light source (LCS-0310-03-23 ​​Mightex Systems, ON, Canada) and subjected to further heat treatment to achieve the color change and further crystallization. [Table 6]

[0137] Examples 9 to 12 Color change of glass due to irradiation with 300 nm LED and heat treatment The lithium silicate glasses of Examples 9 to 12 were irradiated with radiation having a wavelength of 300 nm for 15 minutes using an LED (M300L4, ThorLabs Inc., NJ, USA).

[0138] The irradiated glasses were subjected to heat treatments specified in Table 7. The colors resulting from color changes in the resulting glass-ceramics are also specified in Table 7. Various colorations were found in Examples 9 through 11 in the glass-ceramics containing CeO2, Ag, Sb2O3, Ag, Sb2O3, and SnO. A brown-yellow coloration was observed in Example 12, whose irradiated glass contained Ce, Ag, and Cl.

[0139] Examples 13 to 18 Color changes in glass-ceramics containing Ce, Ag, and Cl upon irradiation with LED and heat treatment The lithium silicate glasses of Examples 13 to 18 were first subjected to heat treatment for nucleation and heat treatment for crystallization. The glass ceramics were irradiated with an LED (LCS-0310-03-23, Mightex Systems, ON, Canada) for 15 minutes, and the radiation contained a portion with a wavelength of 310 nm. The irradiated glass ceramics were then subjected to further heat treatment. The colors achieved by the color change are also specified in Table 7.

[0140] A very high biaxial strength of 604±104 MPa, favorable for use as a dental material, was determined for the glass-ceramic produced in Example 16.

[0141] Examples 19 to 21 Color changes in glass-ceramics due to irradiation with LED or mercury vapor lamps and heat treatment The lithium silicate glasses of Examples 19 to 21 were first subjected to heat treatment for nucleation and heat treatment for crystallization. The glass ceramics were then irradiated with an LED (LCS-0310-03-23, Mightex Systems, ON, Canada) or a mercury vapor lamp for 15 minutes and then subjected to further heat treatment. The colors achieved by the color change are specified in Table 8. Examples 22 to 27 Color change in glass-ceramics crystallized using two heat treatments due to irradiation with LEDs and heat treatment

[0142] The lithium silicate glasses of Examples 22 to 27 were first subjected to one heat treatment for nucleation and two heat treatments for crystallization. The glass-ceramics were irradiated with an LED (LCS-0310-03-23, Mightex Systems, ON, Canada) for 15 minutes and then subjected to further heat treatment.

[0143] For the glass-ceramics of Examples 23 and 24, a darker color could be achieved by a longer duration heat treatment after irradiation.

[0144] For the glass-ceramics of Examples 23 and 25, darker and more intense colors could be achieved by higher temperature heat treatment after irradiation. [Table 7] [Table 8]

[0145] (Examples 28 to 30) Color changes in glass-ceramics containing Ag and Cl or Br or I upon irradiation with LED and heat treatment Glasses were produced using AgCl, AgBr, or AgI as raw materials and subjected to one heat treatment for nucleation and two heat treatments for crystallization. The glass-ceramics were irradiated and subjected to another heat treatment. [Table 9]

[0146] A yellow coloration was observed in the glass-ceramics of Examples 28 to 30 after irradiation and heat treatment.

[0147] Examples 31 to 53 Colour changes in glass-ceramics containing Ce and Au and optionally Ag The compositions of Examples 31 and 32 contained Ce and Au. Examples 33 to 53 also contained Ag in addition to Ce and Au.

[0148] The lithium silicate glass was prepared by a two-step melting process, where the first step was carried out at 1000°C for 30 minutes and the second step was carried out at 1450°C for 60 minutes. The lithium silicate glass was then subjected to a heat treatment for nucleation at 480°C for 10 minutes.

[0149] After the first heat treatment for crystallization, Examples 31 to 39 were subjected to irradiation with an LED light source (LCS-0310-03-23, Mightex Systems, ON, Canada) at 310 nm and 400 mA. The irradiated glass-ceramics were subjected to further heat treatment, and the color was determined.

[0150] Examples 31 and 32 These examples show that reddish coloration can be achieved by irradiation and heat treatment of glass-ceramics containing Ce and Au. A more intense red coloration could be achieved with a higher Au content.

[0151] Examples 33 to 35 These examples show that more intense coloration can be achieved by longer heat treatment after irradiation of glass-ceramics containing Ce, Au, and Ag. It can be particularly observed that longer heat treatment results in a more intense red coloration.

[0152] Examples 36 to 38 In these examples, it was found that higher temperature heat treatment after irradiation achieved more intense coloration, in particular, more intense red coloration was found at higher temperatures.

[0153] Examples 40 to 53 were first subjected to two heat treatments for crystallization, and then irradiated with a 310 nm, 400 mA LED light source (LCS-0310-03-23, Mightex Systems, ON, Canada). The irradiated glass-ceramics were subjected to further heat treatments, and the color was determined.

[0154] Examples 40 to 42 These examples show that stronger coloration, especially stronger red coloration, can be achieved by longer heat treatment after irradiation of glass-ceramics containing Ce, Au, and Ag.

[0155] Examples 42 to 44 In these examples, it was found that higher temperature heat treatment after irradiation achieved stronger coloration of glass-ceramics containing Ce, Au, and Ag. In particular, stronger red coloration was found at higher temperatures.

[0156] Examples 45 to 47 Comparison of these examples with Examples 42 to 44 shows that the desired color effect can be achieved if the heat treatment of the irradiated glass-ceramic is accomplished for a shorter duration but at a higher temperature. More intense coloration, especially more intense red coloration, can also be achieved with higher temperatures.

[0157] (Examples 48 to 50 and Examples 51 to 53) These examples show that more intense coloration can be achieved with longer irradiation durations, especially a more intense red coloration was observed with longer irradiation durations. [Table 10] [Table 11] [Table 12]

[0158] (Examples 54 to 74 and 76 to 78) Color changes in glass-ceramics due to irradiation with LEDs and heat treatment The glasses of these examples were first subjected to heat treatment for nucleation and heat treatment for crystallization. The glass-ceramics were irradiated with an LED light source (LCS-0310-03-23, Mightex Systems, ON, Canada) and subjected to further heat treatment.

[0159] These examples show that color changes can be achieved using irradiation and heat treatment of glass-ceramics with distinct compositions, such as those with low (Example 54) or high (Example 55) P2O5 contents, high Ce and Ag contents (Example 57), or ZrO2 contents (Example 61).

[0160] Examples 71 and 77 These examples demonstrate that the color change achieved by irradiation and heat treatment can be combined with other coloring processes. The Er2O3 present in the compositions of Examples 71 and 77 introduced into the glass-ceramics produced a slight red coloration, but the overall color of the glass-ceramics irradiated and heat-treated according to the present invention was yellow. The red coloration of the glass-ceramics of Examples 71 and 77 was observed by a * The values ​​were determined by a * The values ​​were higher compared to glass-ceramics without red coloring components, such as Example 70.

[0161] Example 78 The chemical resistance of the glass ceramic according to Example 78 according to ISO 6872 (2008) was 18 μg / cm 2 This resulted in an acid solubility of .

[0162] (Examples 80 to 90) Color changes in low-temperature quartz and lithium aluminosilicate glass-ceramics The glasses were produced in a two-step melting process and subjected to heat treatment for nucleation. After heat treatment for crystallization, color change was performed by irradiation and heat treatment to determine the resulting crystalline phase.

[0163] The examples also show that color changes can be achieved by irradiation and heat treatment of glass-ceramics having low-temperature quartz or lithium aluminosilicate as the predominant crystalline phase. [Table 13] [Table 14] [Table 15]

[0164] Example 91 Color changes due to irradiation with X-rays and heat treatment The glass ceramic is subjected to a nucleation duration t N A glass ceramic was prepared according to Example 74, except that the time was 10 minutes. After heat treatment for crystallization, Li2Si2O5 was determined as the main crystalline phase, and Li3PO4 and low-temperature quartz were determined as secondary crystalline phases. The glass ceramic was irradiated with Cu-Kα radiation for 2 hours using an X-ray diffractometer (D8 Advance, Bruker, Karlsruhe, Germany) with an operating voltage of 40 kV. After irradiation with high-energy radiation, which already involves thermal effects, a slight yellow coloration of the glass ceramic was already observed. The yellow coloration was strengthened by subsequent heat treatment (750 °C, 10 minutes).

[0165] (Examples 92 to 110) Color change through one-step coloring process The glasses were prepared by a two-step melting process and subjected to heat treatment for nucleation. The glasses of Examples 92 to 99 were subjected to two heat treatments, and the glasses of Examples 100 to 110 were subjected to one heat treatment for crystallization to prepare glass-ceramics.

[0166] For glass-ceramics, the color change was achieved in a one-step process by heating the glass-ceramics at temperatures ranging from 200 to 800° C. and irradiating them in the heated state. The heat treatment and color change process parameters, as well as the resulting colors and crystalline phases determined in the colored glass-ceramics, are shown in Tables 15A and 15B.

[0167] The examples show that color changes can be achieved in glass-ceramics by irradiation and heat treatment, also in a one-step process, in which the heated ceramic is irradiated.

[0168] Furthermore, the examples show that yellow coloring or red or pink coloring can be achieved in glass ceramics using a one-step coloring process. A lower temperature is typically required to achieve yellow coloring than to achieve red coloring. The coloring intensity can be controlled, for example, by the amount of Ag, Au, and / or Ce and the temperature during irradiation. [Table 15A] [Table 15B]

[0169] Example 111 Preparation of multicolored glass-ceramics in a three-step coloring process A glass was prepared according to Example 40, heated at 480°C for 10 minutes for nucleation, and then subjected to two heat treatments for crystallization: the first heat treatment was carried out at 550°C for 60 minutes, and the second heat treatment was carried out at 850°C for 7 minutes.

[0170] The glass ceramic was then subjected to a three-step coloring process. First, red coloring was achieved by irradiating the glass ceramic at 100 °C for 15 min (310 nm LED, 400 mA) in the first step, followed by a heat treatment in the second step. The heat treatment was carried out at 850 °C for 10 min, with heating and cooling rates of 60 K min−1.-1 In a third step, a yellow coloration was further achieved in the red-colored glass ceramic. For this purpose, the glass ceramic was irradiated at 500°C for 10 minutes (310 nm LED, 400 mA) in a manner similar to Examples 91 to 109. Different regions of the glass ceramic were at least partially subjected to the first and second irradiations.

[0171] The resulting glass-ceramic exhibited red and yellow coloration after the third step, with differently irradiated parts of the glass-ceramic exhibiting different colors. In the polychromatic glass-ceramic, the crystalline phases lithium disilicate (Li2Si2O5) and lithium phosphate (Li3PO4) were determined.

[0172] (Comparative Examples 75 and 79) No irradiation of glass or glass ceramic The lithium silicate glasses of Comparative Examples 75 and 79 were subjected to heat treatment for nucleation and heat treatment for crystallization. Unlike glasses and glass ceramics that were further exposed to irradiation and heat treatment, the glass ceramic produced in Comparative Example 75, for example, was not colored. [Table 16]

[0173] The glass ceramic according to Comparative Example 79 was similar to the glass ceramic according to Example 74, with a melting point of 2.46 MPa m 0.5 Fracture toughness (K according to the SEVNB method as described in ISO 6872 of 2008) IC value). In an embodiment of the present invention, for example, the following items are provided: (Item 1) 1. A method for preparing a multicolored dental restoration, comprising: a) giving the glass or glass ceramic the shape of the dental restoration; b) A method in which a color change is achieved in at least a portion of the glass or glass-ceramic by irradiating said portion with artificial electromagnetic radiation and subjecting said irradiated portion to a heat treatment. (Item 2) 2. The method according to item 1, wherein the irradiation and heat treatment of step b) are carried out in one step. (Item 3) 3. The method according to claim 1 or 2, wherein the glass and the glass ceramic comprise at least one oxidizing component and at least one reducing coloring component. (Item 4) The glass and the glass ceramic contain Ce and CeO 2 4. The method according to any one of items 1 to 3, wherein the hydroxybenzoate is present in an amount of preferably 0.01% to 1.5% by weight, in particular 0.03% to 1% by weight, calculated as (Item 5) The glass and the glass ceramic contain Ag, 2 5. The method according to any one of items 1 to 4, wherein the amount of 0.0005% to 1.3% by weight, in particular 0.002% to 0.7% by weight, calculated as O. (Item 6) The glass and the glass ceramic contain Au, 2 6. The method according to any one of items 1 to 5, wherein the compound is present in an amount of preferably 0.0001% to 0.65% by weight, in particular 0.0003% to 0.25% by weight, particularly preferably 0.003% to 0.2% by weight, calculated as O. (Item 7) 7. The method according to any one of items 1 to 6, wherein the glass and the glass ceramic contain Ce and Ag and / or Au. (Item 8) 8. The method according to any one of items 1 to 7, wherein the glasses and glass ceramics contain Cl, Br, and / or I, in particular Cl, in an amount of 0.0001 wt. % to 0.9 wt. %, particularly preferably 0.0005 wt. % to 0.7 wt. %. (Item 9) The glass and the glass ceramic are 2 O 5 in particular in an amount of 0.5 to 11.0% by weight, preferably 0.9 to 10.0% by weight, particularly preferably 0.9 to 8.0% by weight, more preferably 2.0 to 8.0% by weight, even more preferably 2.0 to 6.0% by weight. (Item 10) The glass and the glass ceramic contain 1.0 to 12.0% by weight, in particular 1.0 to 10.0% by weight, particularly preferably 2.0 to 8.0% by weight of K. 2 10. The method of any one of items 1 to 9, comprising O. (Item 11) The glass and the glass ceramic contain 0 to 14.0% by weight, in particular 1.0 to 14.0% by weight, preferably 2.0 to 12.0% by weight, particularly preferably 2.0 to 10.0% by weight of Al. 2 O 3 11. The method according to any one of items 1 to 10, comprising: (Item 12) The glass and the glass ceramic have the following composition: Table C 12. The method according to any one of items 1 to 11, comprising at least one, preferably all, of the following in the amounts indicated: (Item 13) 13. The method according to any one of items 1 to 12, wherein the radiation has a wavelength of less than or equal to 380 nm, in particular in the range of 100 nm to 360 nm, particularly preferably in the range of 250 nm to 350 nm, and most preferably in the range of 300 nm to 310 nm. (Item 14) 14. The method according to any one of items 1 to 13, wherein the heat treatment is carried out at a temperature in the range of from 300°C to 1000°C, in particular from 400°C to 950°C, particularly preferably from 450°C to 850°C. (Item 15) 15. The method according to any one of the preceding items, wherein the heat treatment is carried out for a duration of up to 120 minutes, in particular up to 60 minutes. (Item 16) 14. The method according to any one of items 1 to 13, wherein the color change is achieved in at least a part of the glass ceramic by heating this part to at least 150°C, preferably from 150°C to 800°C, in particular from 200°C to 800°C, particularly preferably from 300°C to 700°C, and irradiating it at this temperature. (Item 17) At least a portion of the glass ceramic is first heated to a temperature T 1 and then subjected to a first irradiation at a temperature T 2 and then subjecting this or another portion of the glass-ceramic to a first heat treatment at a temperature T 3 A color change is achieved by subjecting the material to a second irradiation at T and simultaneously subjecting it to a second heat treatment, where T 1 <T 2 And T 3 <T 2 Preferably, T 1 <T 3 <T 2 17. The method of any one of items 1 to 13 or 16, wherein (Item 18) 18. The method according to any one of the preceding claims, wherein a yellow coloration is achieved in at least one part of the glass or glass ceramic and a red coloration in another part of the glass or glass ceramic. (Item 19) 19. The method according to any one of items 1 to 18, wherein the glasses and glass ceramics are selected from the group consisting of lithium silicate glasses, lithium aluminosilicate glasses, lithium silicate glass ceramics, lithium aluminosilicate glass ceramics, and quartz glass ceramics. (Item 20) 20. The method of claim 19, wherein the glass-ceramic comprises lithium metasilicate, lithium disilicate, low-temperature quartz, or lithium aluminosilicate as the predominant crystalline phase. (Item 21) 21. The method according to any one of items 1 to 20, wherein the glass and the glass-ceramic in which the color change is achieved consist of only one glass and glass-ceramic, respectively. (Item 22) 22. The method according to any one of the preceding items, wherein the glass and the glass ceramic are given the shape of the dental restoration by pressing or machining. (Item 23) 23. The method according to item 22, wherein the machining is performed by a CAD / CAM process. (Item 24) 24. The method of any one of items 1 to 23, wherein the dental restoration is a bridge, an inlay, an onlay, a veneer, an abutment, a partial crown, a crown, or a facet. (Item 25) 25. A multicolored dental restoration obtainable by the method according to any one of items 1 to 24. (Item 26) 1. Use of a glass or glass ceramic as dental material, in particular for preparing a polychromatic dental restoration, in which a color change is achieved in at least a part of the glass or glass ceramic by irradiating said part with artificial electromagnetic radiation and subjecting said irradiated part to a heat treatment. (Item 27) 27. Use according to item 26, wherein the glass and the glass ceramic are subjected to the method according to any one of items 1 to 24.

Claims

1. 1. A method for preparing a multicolored dental restoration, comprising: a) giving the glass or glass ceramic the shape of the dental restoration; b) a color change is achieved in at least a portion of the glass or glass-ceramic by irradiating said portion with artificial electromagnetic radiation and subjecting said irradiated portion to a heat treatment; wherein the glass and the glass ceramic are ２ O ５ , comprising at least one oxidizing component and at least one reducing coloring component; the radiation has a wavelength of 380 nm or less; method.

2. The method of claim 1 , wherein the irradiation and the heat treatment of step b) are performed in one step.

3. The method of claim 1 or 2, wherein the glass and the glass ceramic contain Ce.

4. 4. The method of claim 1, wherein the glass and the glass ceramic comprise Ag.

5. The method of claim 1 , wherein the glass and the glass-ceramic comprise Au.

6. 6. The method according to claim 1, wherein the glass and the glass ceramic contain Ce and Ag and / or Au.

7. 7. The method according to claim 1, wherein the glass and the glass ceramic contain Cl, Br, and / or I.

8. The glass and the glass ceramic are ２ O ５ 8. The method of claim 1, wherein the amount of the hydroxybenzoate is from 0.5% to 11.0% by weight.

9. The glass and the glass ceramic contain 1.0 to 12.0 wt. % K. ２ The method of any one of claims 1 to 8, comprising:

10. The glass and the glass ceramic contain 0 to 14.0 wt. % Al ２ O ３ 10. The method of claim 1, comprising:

11. The glass and the glass ceramic have the following components: Table C 11. The method of claim 1, comprising at least one of the following in the amounts indicated:

12. 12. The method of claim 1, wherein the radiation has a wavelength in the range of 100 nm to 360 nm.

13. 13. The method according to any one of claims 1 to 12, wherein the heat treatment is carried out at a temperature in the range of from 300°C to 1000°C.

14. 14. The method according to any one of claims 1 to 13, wherein the heat treatment is carried out for a duration of up to 120 minutes.

15. 13. The method according to any one of claims 1 to 12, wherein the color change is achieved in at least a portion of the glass ceramic by heating said portion to at least 150°C and irradiating it at this temperature.

16. In at least a portion of the glass ceramic, the portion is first heated to a temperature T １ and then subjected to a first irradiation at a temperature T ２ and then subjecting this or another portion of the glass-ceramic to a first heat treatment at a temperature T ３ A color change is achieved by subjecting the film to a second irradiation at T １ <T ２ And T ３ <T ２ 16. The method of any one of claims 1 to 12 or 15, wherein

17. 17. The method according to claim 1, wherein a yellow coloration is achieved in at least one portion of the glass or glass ceramic and a red coloration in another portion of the glass or glass ceramic.

18. 18. The method of any one of claims 1 to 17, wherein the glass and the glass ceramic are selected from the group consisting of lithium silicate glasses, lithium aluminosilicate glasses, lithium silicate glass ceramics, lithium aluminosilicate glass ceramics, and quartz glass ceramics.

19. 20. The method of claim 18, wherein the glass-ceramic comprises lithium metasilicate, lithium disilicate, low-temperature quartz, or lithium aluminosilicate as a predominant crystalline phase.

20. 20. The method according to any one of claims 1 to 19, wherein the glass and the glass-ceramic in which the color change is achieved consist of only one glass and glass-ceramic, respectively.

21. 21. The method according to any one of claims 1 to 20, wherein the glass and glass ceramic are given the shape of the dental restoration by pressing or machining.

22. The method of claim 21 , wherein the machining is performed in a CAD / CAM process.

23. 23. The method of any one of claims 1 to 22, wherein the dental restoration is a bridge, an inlay, an onlay, a veneer, an abutment, a partial crown, a crown, or a facet.

24. A multicolored dental restoration obtainable by the method according to any one of claims 1 to 23.

25. 1. Use of a glass or glass ceramic as a dental material, wherein a color change is achieved in at least a part of said glass or said glass ceramic by irradiating said part with artificial electromagnetic radiation and subjecting said irradiated part to a heat treatment, wherein said glass and said glass ceramic are selected from the group consisting of P ２ O ５ , at least one oxidizing component and at least one reducing coloring component, said radiation having a wavelength of 380 nm or less.

26. 26. Use according to claim 25, wherein the glass and the glass ceramic are subjected to the method according to any one of claims 1 to 23.

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