Fluorescent glass ceramics and glasses containing cerium and tin

Description

[0001] The present invention relates to glass ceramics and glasses containing cerium and tin, which are particularly suitable for the production of dental restorations whose fluorescence properties largely correspond to those of natural teeth. The invention also relates to a method for producing the glass ceramics and glasses according to the invention, as well as their use as dental materials and, in particular, for the production of dental restorations.

[0002] Glass ceramics are used in dentistry, particularly for the production of dental crowns and small bridges, due to their good mechanical and optical properties.

[0003] EP 0 916 625 A1 describes lithium disilicate glass ceramics containing lithium disilicate as the main crystal phase. Due to their high translucency and excellent mechanical properties, they are particularly suitable for dental applications, primarily for the fabrication of crowns and bridges. To match the color of the glass ceramic products to the natural tooth structure, the glass ceramics may contain color and fluorescent components, preferably selected from the group consisting of CeO₂, V₂O₅, Fe₂O₃, MnO₂, TiO₂, Y₂O₃, Er₂O₃, Tb₄O₇, Eu₂O₃, Yb₂O₃, Gd₂O₃, Nd₂O₃, Pr₂O₃, Dy₂O₃, Ag₂O, SnO₂, and Ta₂O₅.

[0004] WO 2015 / 173394 A1 describes glass ceramics that have SiO₂ as the main crystal phase and are also suitable for the fabrication of dental restorations. These glass ceramics may contain oxides of Sc, Mn, Fe, Co, Pr, Nd, Tb, Er, Dy, Gd, Eu, and Yb as coloring agents or fluorescent agents.

[0005] From W. Buchalla, "Comparative Fluorescence Spectroscopy Shows Differences in Non-Cavitated Enamel Lesions", Caries Res. 2005, 39, 150-156, it is known that natural teeth show a bluish-white fluorescence under ultraviolet light with wavelengths in the range of 400 to 650 nm.

[0006] Rukmani et al., J. Am. Ceram. Soc. 2007, 90, 706-711, describe the influence of V and Mn dyes on the crystallization behavior and optical properties of Ce-doped lithium disilicate glass ceramics. To produce the glass ceramics, a mixture of the starting materials SiO₂, ZrO₂, Li₂CO₃, K₂CO₃, MgCO₃, and Al(PO₃)₃ with CeO₂, V₂O₅, and MnO₂ is prepared. The mixture is melted at 1500°C in platinum crucibles, cooled, and then subjected to several heat treatments in a tube furnace with air supply.

[0007] WO 2014 / 081454 A1 and US 2010 / 083706 A1 describe glass ceramics for the manufacture of dental restorations, which may contain, among other things, cerium and tin.

[0008] However, it has been shown that the glasses and glass-ceramics known from the prior art exhibit insufficient fluorescence properties and, in particular, cannot adequately imitate the fluorescence properties of natural tooth material under UV light. As a result, dental restorations made from such glass-ceramics are recognizable as restorations, especially under the influence of UV light, or are perceived as gaps or defects.

[0009] Methods for producing glasses and glass ceramics with improved fluorescence properties have also been described.

[0010] WO 2015 / 173230 A1 describes a process for producing a lithium silicate glass or a lithium silicate glass-ceramic in which a melt of a starting glass containing cerium ions is subjected to reducing conditions. This is intended to reduce the Ce⁴⁺ ions contained in the starting glass wholly or partially to Ce³⁺ ions, which exhibit fluorescence in the wavelength range of 320 to 500 nm due to 5d→4f transitions. A corresponding process for producing a glass-ceramic with SiO₂ as the main crystal phase or a glass containing nuclei for the crystallization of SiO₂ is known from WO 2017 / 080853 A1.

[0011] A disadvantage of the known methods, however, is that the ratio of Ce³⁺ and Ce⁴⁺ ions can only be controlled to a limited extent. Furthermore, heat treatments under oxidizing conditions, such as sintering, can shift this ratio in favor of Ce⁴⁺ ions in the glasses and glass-ceramics produced in this way, which can significantly impair the fluorescence properties.

[0012] The invention is based on the objective of providing glass ceramics and glasses that exhibit fluorescence comparable to that of natural tooth material and are largely insensitive to heat treatments and oxidizing conditions, and are therefore particularly suitable for the production of dental restorations that not only possess good mechanical properties but can also largely imitate the fluorescence properties of natural tooth material at excitation wavelengths across the entire relevant UV range. In particular, the glass ceramics and glasses should also be suitable as mixture components for adjusting the fluorescence properties of other glasses and glass ceramics.

[0013] This problem is solved according to the invention by a glass or a glass-ceramic containing cerium and tin, which includes the following components: component % by weight SiO2 59.0 to 80.0 Al2O3 0.1 to 42.0 Cerium, calculated as CeO₂ 0.5 to 10.0 Tin, calculated as SnO 0.1 to 4.0 B2O3 another tetravalent oxide 0 to 5.0 Elements Me IV< O 2 0 to 4, 0, wherein the term "further oxide of tetravalent elements Me IV< O 2" means tetravalent oxides except for SiO 2 , CeO 2 , SnO 2 and TiO 2 and this Me IV< O 2 is in particular selected from ZrO 2 and / or GeO 2 and wherein the molar ratio of cerium, calculated as CeO 2 , to tin, calculated as SnO, is in the range of 10:1 to 1:1.

[0014] It has surprisingly been shown that the glass and glass-ceramic according to the invention exhibit improved fluorescence properties compared to the prior art, particularly under the influence of UV light, which are precisely and reproducibly adjustable and largely stable against heat treatments and oxidizing conditions.

[0015] Without being limited to a specific theory, it is assumed that an equilibrium is established in the glasses and glass ceramics according to the invention between Ce³⁺ / Ce⁴⁺ and Sn²⁺ / Sn⁴⁺. This stabilizes the ratio of Ce³⁺ and Ce⁴⁺ ions and largely prevents an undesirable shift of this ratio towards Ce⁴⁺ ions, for example during heat treatments, particularly under oxidizing conditions. Due to 5d→4f transitions, the Ce³⁺ ions exhibit fluorescence in the wavelength range of 320 to 500 nm, which is particularly suitable for imitating the fluorescence properties of natural tooth material. In addition, Ce⁴⁺ ions cause a yellowing of the glasses and glass ceramics. Thus, a particularly good imitation of the fluorescence and color properties of natural tooth material is enabled.

[0016] According to the invention, it is preferred that the glass and the glass-ceramic contain 59.0 to 77.0, in particular 59.0 to 76.0, preferably 64.0 to 75.0 and particularly preferably 70.0 to 74.0 wt.% SiO2.

[0017] Furthermore, it is preferred that the glass and the glass-ceramic contain 0.3 to 39.0, in particular 0.5 to 30.0, preferably 1.0 to 20.0, particularly preferably 1.5 to 10.0 and most preferably 2.0 to 6.0 wt.% Al 2 O 3.

[0018] Preferably the glass and the glass-ceramic contain 0.7 to 7.5, in particular 1.0 to 7.0, preferably 1.5 to 5.0 and particularly preferably 2.0 to 4.0 wt.% Cer, calculated as CeO 2 .

[0019] It is further preferred that the glass and the glass-ceramic contain 0.2 to 3.0, in particular 0.3 to 2.0 and preferably 0.4 to 1.0 wt.% tin, calculated as SnO.

[0020] It is also preferred that the molar ratio of cerium, calculated as CeO 2 , to tin, calculated as SnO, is in the range of 5:1 to 1:1, preferably 3:1 to 1:1 and particularly preferably 2:1 to 1:1.

[0021] In a particular embodiment, the glass and the glass-ceramic further contain terbium. Preferably, the glass and the glass-ceramic contain 0 to 2.0 wt.%, in particular 0.05 to 1.5 wt.%, more preferably 0.1 to 1.0 wt.%, and most preferably 0.3 to 0.7 wt.% terbium, calculated as Tb₄O₇. It has surprisingly been found that, according to the invention, glasses and glass-ceramics can be obtained by combining cerium ions and terbium ions, whose fluorescence and color properties can particularly well imitate those of natural tooth material. It is particularly surprising that, in the glasses and glass-ceramics according to the invention, the fluorescence caused by the cerium ions largely persists even in the presence of terbium ions, although a reduction or even extinction of the cerium ion-induced fluorescence in the presence of d-cells was observed in the prior art.

[0022] It is further preferred that the glass and the glass-ceramic contain 0 to 18.0, in particular 1.0 to 17.0, preferably 3.0 to 16.0 and particularly preferably 7.5 to 10.0 wt.% Li₂O. Li₂O serves in particular to improve the meltability of the starting glasses.

[0023] It is also preferred that the glass and the glass-ceramic contain further alkali metal oxide MeI<2O in an amount of 0 to 13.0, in particular 1.0 to 7.0 and preferably 3.0 to 5.0 wt.%. The term "further alkali metal oxide MeI<2O" means alkali metal oxide other than Li₂O, wherein this MeI<2O is in particular selected from Na₂O, K₂O, Rb₂O and / or Cs₂O, preferably selected from Na₂O and / or K₂O, and most preferably is K₂O. The glass and the glass-ceramic particularly preferably contain at least one and in particular all of the following further alkali metal oxides MeI<2O in the specified amounts: component % by weight Na₂O 0 to 8.0 K2O 0 to 5.0 Rb 2 O 0 to 7.0 Cs 2 O 0 to 13.0.

[0024] Furthermore, it is preferred that the glass and the glass-ceramic contain 0 to 22.0 wt.%, in particular 1.0 to 16.0 wt.%, preferably 2.0 to 10.0 wt.%, and most preferably 3.0 to 6.0 wt.% of further oxides of divalent elements Me II < O. The term "further oxides of divalent elements Me II < O" refers to divalent oxides with the exception of BaO and SnO, wherein these Me II < O are in particular selected from MgO, CaO, SrO, and / or ZnO. Particularly preferably, the glass and the glass-ceramic contain at least one, and in particular all, of the following oxides of divalent elements Me II < O in the specified amounts: component % by weight MgO 0 to 13, 0 CaO 0 to 4.0 SrO 0 to 3.0 ZnO 0 to 4.0.

[0025] Furthermore, it is preferred that the glass and the glass-ceramic contain 0 to 10.0, in particular 0 to 5.0 and preferably 0 to 1.0 wt% BaO and are most preferably essentially free of BaO.

[0026] A glass and a glass-ceramic are preferred, containing 0 to 10.0, in particular 0.5 to 4.0, and preferably 1.0 to 2.5 wt.% of further oxides of trivalent elements Me III < 2 O 3. The term "further oxides of trivalent elements Me III < 2 O 3" refers to trivalent oxides with the exception of Al 2 O 3 and Ce 2 O 3, wherein this Me III < 2 O 3 is in particular selected from B 2 O 3, Y 2 O 3, La 2 O 3, Ga 2 O 3 and / or In 2 O 3, and preferably selected from B 2 O 3, Y 2 O 3 and / or La 2 O 3. The glass and the glass-ceramic particularly preferably contain at least one, and in particular all, of the following further oxides of trivalent elements Me III < 2 O 3 in the specified amounts: component % by weight B2O3 0 to 5, 0 Y2O3 0 to 3, 0 La 2 O 3 0 to 2, 0 Ga2O3 0 to 2, 0 In 2 O 3 0 to 1.0.

[0027] Furthermore, the glass and the glass-ceramic may contain additional oxides of tetravalent elements MeIVO2 in an amount of 0 to 4.0, in particular 0.5 to 4.0, and preferably 1.0 to 2.5 wt.%. The term "additional oxides of tetravalent elements MeIVO2" refers to tetravalent oxides with the exception of SiO2, CeO2, SnO2, and TiO2, wherein this MeIVO2 is particularly selected from ZrO2 and / or GeO2. The glass and the glass-ceramic particularly preferably contain at least one, and in particular all, of the following additional oxides of tetravalent elements MeIVO2 in the specified amounts: component % by weight ZrO 2 0 to 4, 0 GeO 2 0 to 4, 0.

[0028] Furthermore, it is preferred that the glass and the glass-ceramic contain 0 to 5.0, in particular 0 to 2.5 and preferably 0 to 1.0 wt% TiO2 and are most preferably essentially free of TiO2.

[0029] In a preferred embodiment, the glass and the glass-ceramic further contain oxides of pentavalent elements MeV2O5 in an amount of 0 to 8.0 wt.%, particularly 1.0 to 6.0 wt.%, more preferably 2.0 to 5.0 wt.%, and most preferably 3.0 to 4.0 wt.%, wherein this MeV2O5 is particularly selected from P2O5, V2O5, Ta2O5, and / or Nb2O5, more preferably selected from P2O5 and / or Ta2O5, and most preferably P2O5. P2O5 can particularly act as a nucleating agent. However, the presence of a nucleating agent is not essential according to the invention. Particularly preferably, the glass and the glass-ceramic contain at least one, and more preferably all, of the following further oxides of pentavalent elements MeV2O5 in the specified amounts: component % by weight P2O5 0 to 5, 0 V2O5 0 to 6, 0 Ta 2 O 5 0 to 5, 0 Nb 2 O 5 0 to 5, 0.

[0030] The glass and glass-ceramic may also contain 0 to 6.0 wt% oxide of hexavalent elements MeVI< O 3, wherein this MeVI< O 3 is in particular selected from WO 3 and / or MoO 3. Particularly preferably, the glass and glass-ceramic contain at least one and in particular all of the following oxides MeVI< O 3 in the specified amounts: component % by weight WO 3 0 to 6, 0 MoO 3 0 to 5, 0.

[0031] The glass and glass-ceramic may also contain oxides of other f-elements, such as oxides of Pr, Nd, Gd, Dy, Er and Yb, and in particular oxides of Er.

[0032] Furthermore, the glass and glass-ceramic may contain 0 to 5.0 and in particular 0 to 2.0 wt% fluorine.

[0033] Particularly preferred are a glass and a glass-ceramic comprising at least one and preferably all of the following components in the specified quantities: component % by weight SiO2 59.0 to 77.0 Al2O3 0.3 to 39.0 Cerium, calculated as CeO₂ 0.7 to 7.5 Tin, calculated as SnO 0.2 to 3.0 Terbium, calculated as Tb4O7 0 to 2.0 Li 2 O 0 to 18, 0 Me I< 2 O 0 to 13.0 Me II< O 0 to 22, 0 Me III < 2 O 3 0 to 10.0 Me IV< O 2 0 to 4, 0 Me V< 2 O 5 0 to 8.0 Me VI< O 3 0 to 6.0 fluorine 0 to 5.0,

[0034] where Me I< 2 O, Me II< O, Me III< 2 O 3 , Me IV< O 2 , Me V< 2 O 5 and Me VI< O 3 have in particular the meanings given above.

[0035] In a further particularly preferred embodiment, the glass and the glass-ceramic contain at least one and preferably all of the following components: component % by weight SiO2 59.0 to 77.0 Al2O3 0.3 to 39.0 Cerium, calculated as CeO₂ 0.7 to 7.5 Tin, calculated as SnO 0.2 to 3.0 Terbium, calculated as Tb4O7 0 to 2, 0 Li 2 O 0 to 18.0 Na₂O 0 to 8, 0 K2O 0 to 5.0 Rb 2 O 0 to 7.0 Cs 2 O 0 to 13.0 MgO 0 to 13.0 CaO 0 to 4.0 SrO 0 to 3.0 ZnO 0 to 4.0 BaO 0 to 10.0 B2O3 0 to 5.0 Y2O3 0 to 3.0 La 2 O 3 0 to 2.0 Ga2O3 0 to 2.0 In 2 O 3 0 to 1.0 ZrO 2 0 to 4.0 GeO 2 0 to 4.0 TiO2 0 to 5.0 P2O5 0 to 5.0 V2O5 0 to 6, 0 Ta 2 O 5 0 to 5.0 Nb 2 O 5 0 to 5.0 WO 3 0 to 6.0 MoO 3 0 to 5.0 He 2 O 3 0 to 1, 0 fluorine 0 to 5.0.

[0036] The invention also relates to precursors with a corresponding composition from which the glass-ceramic according to the invention can be produced by heat treatment. These precursors are a correspondingly composed glass (also referred to as a starting glass) and a correspondingly composed glass with nuclei. The term "corresponding composition" means that these precursors contain the same components in the same quantities as the glass-ceramic, wherein the components, with the exception of fluorine, are calculated as oxides, as is customary for glasses and glass-ceramics.

[0037] The invention also relates to a glass according to the invention which contains nuclei for crystallization. By heat-treating the glass according to the invention, the glass according to the invention with nuclei can first be produced, which in turn can be transformed into the glass-ceramic according to the invention by further heat treatment.

[0038] The invention also relates to a method for producing the glass or glass ceramic according to the invention, in which the tin is used in divalent form and in particular as SnO.

[0039] The glass according to the invention is produced in particular by melting a mixture of suitable starting materials, such as carbonates, oxides, phosphates and fluorides, at temperatures of in particular 1500 to 1800°C for 0.5 to 10 hours. To achieve particularly high homogeneity, the resulting molten glass can be poured into water to form glass granules, and the resulting granules can then be remelted.

[0040] The molten glass can then be poured into molds, such as steel or graphite molds, to produce glass blanks, also known as solid glass blanks or monolithic blanks. These monolithic blanks are typically first stress-relieved, for example by holding them at 450 to 600°C for 5 to 120 minutes.

[0041] It is also possible to re-immerse the molten glass in water to produce granules. These granules can then be ground and, if necessary, further components added before being pressed into a blank, a so-called powder pellet. Finally, the granulated glass can also be processed into a powder.

[0042] The glass can then be heat-treated to produce glass containing nuclei. This is also referred to as the nucleation process. The invention is therefore also directed to a method for producing glass with nuclei, in which the glass is subjected to heat treatment at a temperature of 450 to 600°C, and in particular 500 to 550°C, for a duration of, in particular, 5 to 120 minutes, and preferably 10 to 60 minutes.

[0043] The glass containing nuclei can then be used to form the glass ceramic according to the invention by heat treatment. The invention is therefore also directed to a method for producing the glass ceramic according to the invention, in which the glass, in particular the glass containing nuclei, is subjected to at least one heat treatment at a temperature of 700 to 950°C for a duration of, in particular, 5 to 120 minutes and preferably 10 to 60 minutes.

[0044] The glass according to the invention or the glass according to the invention with nuclei can, for example, be in the form of a solid glass blank or a powder compact and subjected to at least one heat treatment.

[0045] The at least one heat treatment carried out in the inventive method can also be carried out in the context of hot pressing, in particular of a solid glass blank, or in the context of sintering, in particular of a powder.

[0046] Thus, in a preferred embodiment, the invention relates to a method for producing the glass ceramic according to the invention, wherein (a) Powder of the glass according to the invention, optionally after the addition of further components, such as other glasses, glass ceramics and / or pressing aids, is pressed into a powder pellet, and (b) the powder pellet is subjected to heat treatment at a temperature of 700 to 950°C for a duration of in particular 5 to 120 min.

[0047] In a further preferred embodiment, the invention relates to a method for producing the glass ceramic according to the invention, wherein (a') the molten glass is formed into a glass blank, in particular by pouring it into a mold, and (b') the glass blank is subjected to heat treatment at a temperature of 700 to 900°C for a duration of in particular 5 to 120 min.

[0048] In both preferred embodiments of the method according to the invention, nucleation may optionally be carried out before the heat treatment in step (b) or (b').

[0049] The invention further relates to a glass and a glass ceramic according to the invention, which have a whitish-blue fluorescent color in the CIE color space.

[0050] The glasses and glass-ceramics according to the invention, containing cerium and tin, are particularly suitable as mixture components for adjusting the fluorescence properties of other glasses and glass-ceramics. A glass or glass-ceramic containing the glass or glass-ceramic according to the invention, containing cerium and tin, therefore constitutes a further object of the invention. A glass or glass-ceramic containing the glass or glass-ceramic according to the invention, containing cerium and tin, is particularly preferred in an amount of 0.1 to 50 wt.%, in particular 0.2 to 40 wt.%, preferably 0.5 to 30 wt.%, particularly preferably 1 to 20 wt.%, and most preferably 5 to 10 wt.%.

[0051] The glass or glass-ceramic according to the invention, containing cerium and tin, can be used, in particular, as a component of an inorganic-inorganic composite or in combination with a variety of other glasses and / or glass-ceramics, wherein the composites or combinations can be used, in particular, as dental materials. The composites or combinations are especially preferably available in the form of sintered blanks.Examples of other glasses and glass-ceramics for the production of inorganic-inorganic composites and combinations are found in DE 43 14 817 A1, DE 44 23 793 C1, DE 44 23 794 C1, DE 44 28 839 A1, DE 196 47 739 A1, DE 197 25 552 A1, DE 100 31 431 A1, EP 0 827 941 A1, EP 0 916 625 A1, WO 00 / 34196 A2, EP 1 505 041 A1, EP 1 688 398 A1, EP 2 287 122 A1, EP 2 377 831 A1, EP 2 407 439 A1, WO 2013 / 053863 A2, WO 2013 / 053864 A2, WO 2013 / 053865 A2, WO 2013 / 053866 A2, WO 2013 / 053867 A2, WO 2013 / 053868 A2, WO 2013 / 164256 A1, WO 2014 / 170168 A1, WO 2014 / 170170 A2, WO 2015 / 067643 A1, WO 2015 / 155038 A1, WO 2015 / 173394 A1, WO 2016 / 120146 A1, WO 2017 / 032745 A1, WO 2017 / 055010 A1 disclosed. These glasses and glass ceramics belong to the silicate, borate, phosphate or aluminosilicate group.Preferred glasses and glass-ceramics are of the SiO₂-Al₂O₃-K₂O type (with cubic or tetragonal leucite crystals), SiO₂-B₂O₃-Na₂O type, alkali silicate type, alkali zinc silicate type, silicophosphate type, and / or SiO₂-ZrO₂ type. Lithium silicate glass-ceramics are particularly preferred, especially glass-ceramics containing lithium metasilicate or lithium disilicate as the main crystal phase and optionally further crystal phases such as apatite, diopside, quartz, and / or wollastonite, as well as glass-ceramics containing SiO₂, particularly in the form of low-temperature quartz, as the main crystal phase. By mixing such glasses or glass-ceramics with the glasses and / or glass-ceramics according to the invention containing cerium and tin, the fluorescence properties can be adjusted as desired.

[0052] The glass ceramics and glasses according to the invention, particularly in the form of composites and combinations thereof, are available especially in the form of powders, granules, or blanks of any shape and size, e.g., monolithic blanks such as plates, cuboids, or cylinders, or compressed powders, in unsintered, partially sintered, or fully sintered form. In these forms, they can be easily further processed, e.g., into dental restorations. They can also be available in the form of dental restorations such as inlays, onlays, crowns, partial crowns, bridges, veneers, shells, or abutments.

[0053] Dental restorations, such as inlays, onlays, crowns, partial crowns, bridges, veneers, shells, or abutments, can be produced from the glass ceramics and glasses according to the invention, particularly in the form of composites and combinations thereof. The invention therefore relates to their use as dental materials and, in particular, their use for the production of dental restorations. It is preferred that the glass ceramic or the glass be given the shape of the desired dental restoration by pressing or machining.

[0054] Compression molding is typically carried out under increased pressure and temperature. It is preferred that compression molding is performed at a temperature of 700 to 1150°C, and particularly at 700 to 1000°C. Furthermore, it is preferred that compression molding be carried out at a pressure of 10 to 30 bar. During compression molding, the desired deformation is achieved through the viscous flow of the material used. The glass according to the invention, the glass according to the invention with nucleation sites, and preferably the glass-ceramic according to the invention can be used for compression molding. The glasses and glass-ceramics according to the invention can be used, in particular, in the form of blanks of any shape and size, e.g., solid blanks or powder compacts, e.g., in unsintered, partially sintered, or fully sintered form.

[0055] Machining is typically carried out by material removal processes, particularly milling and / or grinding. It is especially preferred that machining is performed within the framework of a CAD / CAM process. The glass according to the invention, the glass with nuclei according to the invention, and the glass-ceramic according to the invention can be used for machining. The glasses and glass-ceramics according to the invention can be used, in particular, in the form of blanks, e.g., solid blanks or powder compacts, e.g., in unsintered, partially sintered, or densely sintered form. The glass-ceramic according to the invention is preferably used for machining. The glass-ceramic according to the invention can also be used in a form that is not yet fully crystallized, which has been produced by heat treatment at a lower temperature.This offers the advantage of easier machining and thus the use of simpler machining equipment. After machining such a partially crystallized material, it is regularly subjected to further heat treatment to induce further crystallization.

[0056] The glass ceramics and glasses according to the invention, particularly in the form of composites and combinations, are also suitable as coating materials for, for example, ceramics, glass ceramics, and metals. The invention is therefore also directed to the use of the glasses or glass ceramics according to the invention for coating, in particular, ceramics, glass ceramics, and metals.

[0057] The invention also relates to a method for coating ceramics, glass ceramics and metals, in which glass ceramic or glass according to the invention, in particular in the form of composites and combinations, is applied to the ceramic, glass ceramic or metal and exposed to a temperature of at least 600°C.

[0058] This can be achieved in particular by sintering and preferably by pressing. In sintering, the glass-ceramic or glass is applied to the material to be coated, such as ceramic, glass-ceramic, or metal, in the usual manner, e.g., as a powder, and then sintered. In the preferred pressing process, the glass-ceramic or glass according to the invention, e.g., in the form of powder pellets or monolithic blanks, is pressed onto the material at an elevated temperature, e.g., 700 to 1150°C and particularly 700 to 1000°C, and under pressure, e.g., 10 to 30 bar. The methods and the press furnace described in EP 231 773 can be used for this purpose. Suitable commercial furnaces are the Programat type furnaces from Ivoclar Vivadent AG, Liechtenstein.

[0059] Due to the properties of the glass ceramics and glasses according to the invention described above, they are particularly suitable for use in dentistry. The invention therefore also relates to the use of the glass ceramics or glasses according to the invention, particularly in the form of composites and combinations, as dental materials and especially for the production of dental restorations or as coating materials for dental restorations, such as crowns, bridges, and abutments.

[0060] The invention therefore also relates to a method for manufacturing a dental restoration, in particular an inlay, onlay, crown, partial crown, bridge, veneer, shell or abutment, in which the glass ceramic or glass according to the invention, in particular in the form of composites and combinations, is given the shape of the desired dental restoration by pressing, sintering or machining, in particular within the framework of a CAD / CAM process.

[0061] The invention will be explained in more detail below using examples that do not limit it. Examples

[0062] A total of 17 glasses according to the invention were produced with the compositions specified in Table I, wherein the oxidation states of the oxides listed refer to the oxidation states of the raw materials used. The glasses were crystallized to glass-ceramics according to Table II. Here, Tg represents the glass transition temperature, determined by DSC; TS and tS represent the temperature and time used for melting; TN and tN represent the temperature and time used for nucleation; TC and tC represent the temperature and time used for crystallization; and TSinter and tSinter represent the temperature and time used for sintering.

[0063] In the examples, initial glass batches with the compositions specified in Table I were first melted on a scale of 100 to 200 g from common raw materials at temperature TS for a duration t S. Glass frits were then produced by pouring the molten glass batches into water. The four process variants A) to D) listed below were used for further processing of the glass frits: A) Production of sintered powder compacts

[0064] In Examples 1 to 3 (according to the invention) and 4 (comparison), the fluorescence of the obtained glass frits was visually determined under a UV lamp. All glass frits exhibited fluorescence.

[0065] The resulting glass frits were then milled in a zirconia mill to a particle size of < 112 µm. Approximately 4 g of this powder were pressed into cylindrical blanks and subjected to heat treatment at temperature TN for a duration tN, allowing nucleation to occur. Subsequently, the blanks were sintered under vacuum in a sintering furnace (Programat® from Ivoclar Vivadent AG) at temperature Tsinter and a holding time of tsinter to form dense glass-ceramic bodies. The fluorescence of the resulting glass-ceramic bodies was visually determined under a UV lamp. All bodies exhibited fluorescence.

[0066] The examples were repeated, with sintering taking place in air. While in examples 1 to 3 according to the invention only a slightly reduced fluorescence was obtained compared to sintering in a vacuum, no significant fluorescence could be observed in comparative example 4 (no tin). B) Solid glass blocks

[0067] In Examples 5 to 15 (according to the invention) and 16 (comparative), the obtained glass frits were remelted at temperature TS for a duration t S. The resulting melts of the starting glass were then poured into a graphite mold to produce solid glass blocks. The glass monoliths were subsequently annealed at temperature TN for a duration t N, allowing nucleation to occur. The fluorescence of the glass monoliths was then visually determined under a UV lamp. All glass monoliths, with the exception of comparative example 16 (no tin), exhibited fluorescence.

[0068] In Examples 6 to 15 (according to the invention) and 16 (comparative), the glass monoliths were then heated to a temperature TC for a duration t C to form glass ceramics. The fluorescence of the resulting glass ceramics was again determined visually under a UV lamp. All glass ceramics, with the exception of comparative example 16 (no tin), showed fluorescence. C) Glass fries

[0069] In examples 17 and 18, the fluorescence of the obtained glass frits was visually determined under a UV lamp. All glass frits showed fluorescence. D) Glass according to the invention as a mixing component

[0070] A glass frit obtained according to Example 19 was ground and mixed in varying amounts (5, 10, 20, and 30 wt% based on the mixture) with a ground glass powder having a composition according to WO 2015 / 173394 A1. Approximately 4 g of each of these mixtures were then pressed into cylindrical blanks and sintered in a sintering furnace (Programat® from Ivoclar Vivadent AG) at a temperature of 860°C for a holding time of 60 min to form dense glass-ceramic bodies. The fluorescence was then visually determined under a UV lamp. All obtained bodies exhibited fluorescence. Table I Example 1 2 3 4** 5 6 7 8 9 10 composition % by weight Weight -% % by weight Weight -% Weight -% Weight -% % by weight Weight -% Weight -% Weight -% SiO2 73, 8 73,4 70, 8 73,3 63,7 73,2 73,2 73,4 73, 8 76,2 Al2O3 2, 6 2, 6 2, 5 2, 6 5, 4 0, 5 2, 6 2, 6 2, 6 2, 7 CeO 2 1, 3 1, 8 0, 9 - 7, 3 4, 4 1, 8 1, 8 1, 8 0, 9 Ce 2 O 3 * - - - 2, 4 - - - - - - SnO 0, 5 0, 5 0, 3 - 2, 8 1, 4 0, 5 0, 5 0, 5 0, 2 Li 2 O 9, 0 8, 9 7, 9 8, 9 15, 8 7, 9 8, 9 8, 9 8, 6 8, 9 Na₂O - - - K2O 3, 2 3, 2 3, 4 3, 2 5, 0 3, 5 3, 2 3, 2 3, 2 3, 3 MgO 2, 4 2, 4 1, 7 2, 4 - 1, 7 2, 4 2, 4 2, 7 2, 8 CaO - - 3, 0 - - 3, 0 - - - - SrO - - - - - - - - - - ZnO 3, 5 3, 5 - 3, 5 - - 3, 5 3, 5 0, 7 0, 7 B2O3 - - - - - - - - 0, 6 0, 6 Y2O3 - - - - - - - - - - La 2 O 3 - - - - - - - - - - GeO 2 - - 1, 4 - - - - - - - ZrO 2 - - 1, 0 - - - - - - - P2O5 3, 3 3, 3 3, 4 3, 3 - 3, 6 3, 3 3, 3 3, 2 3, 3 V2O5 - - - - - - 0, 1 - - - Ta 2 O 5 - - 3, 7 - - - - - 1, 9 - He 2 O 3 - - - - - - 0, 1 - - - Tb 4 O 7 0, 4 0, 4 - 0, 4 - 0, 8 0, 4 0, 4 0, 4 0, 4 F - - - - - - - - - - Σ 100,0 100,0 100, 0 100,0 100,0 100,0 100,0 100,0 100,0 100,0 Table I Example 11 12 13 14 15 16** 17 18 19 composition % by weight % by weight % by weight % by weight % by weight % by weight % by weight % by weight % by weight SiO2 74, 1 73, 8 73, 8 71, 8 70, 8 76, 5 64, 6 63, 9 73, 9 Al2O3 2, 6 2, 6 2, 6 2, 6 2, 5 2, 7 4, 0 5, 0 0, 5 CeO 2 1, 8 1, 8 1, 8 4, 4 0, 9 0, 9 1, 9 1,7 4, 4 Ce 2 O 3 * - - - - - - - - - SnO 0, 5 0, 5 0, 5 0, 5 0, 3 - 0, 7 0, 7 1, 4 Li 2 O 8, 7 8, 6 8, 9 8, 7 7, 9 9, 2 16, 0 3, 2 8, 0 Na₂O - - - - - - - 7, 4 - K2O 3, 2 3, 2 3, 2 3, 1 3, 4 3, 3 3, 8 4, 6 3, 5 MgO 2, 7 2, 7 2, 4 2, 3 1, 7 3, 0 1, 8 0, 5 1, 7 CaO - - - - 3, 0 - 3, 3 1, 8 3, 0 SrO - - - - - - - 2, 4 - ZnO 0, 7 0, 7 35 3, 4 - 0, 7 - 3, 5 - B2O3 0, 6 0, 6 - - - - - 4, 0 - Y2O3 - 1 9 - - - - - - - La 2 O 3 1, 4 - - - - - - - - GeO 2 - - - - 1, 4 - - - - ZrO 2 - - - - 1, 0 - - - - P2O5 3, 3 3, 2 3, 3 3, 2 3, 4 3, 3 3, 9 - 3, 6 V2O5 - - - - - - - - - Ta 2 O 5 - - - - 3, 7 - - - - He 2 O 3 - - - - - - - - - Tb 4 O 7 0, 4 0, 4 - - - 0, 4 - - - F - - - - - - - 1, 3 - Σ 100,0 100, 0 100,0 100,0 100,0 100,0 100,0 100,0 100,0 * used as cerium(III) acetylacetonate; ** comparison Table II Example 1 2 3 4** 5 6 7 8 9 10 T g [°C] 469 488 TS [°C] 1600 1600 1600 1600 1650 1650 1600 1600 1600 1600 t S [min] 120 120+120 60 120 240 60 120+120 120+120 120+120 120 TN [°C] 500 500 500 500 490 520 500 500 500 500 t N [min] 60 20 20 60 120 10 60 60 60 60 TC [°C] - - - - - 850 820 820 820 820 t C [min] - - - - - 10 30 30 30 30 T Sinter [°C] 860 860 860 860 - - - - - - t Sinter [min] 30 60 60 30 - - - - - - Fluorescent glass blue intense blue blue and white blue blue blue and white blue intense blue blue blue Fluorescence glass ceramic blue blue blue and white blue blue and white blue intense blue blue blue Table II Example 11 12 13 14 15 16** 17 18 T g [°C] 435 445 TS [°C] 1600 1600 1600 1600 1600 1600 1600 1600 t S [min] 120 120 120+120 120+120 60 120 120 60 TN [°C] 500 500 490 500 500 500 - - t N [min] 60 60 10 10 10 60 - - TC [°C] 820 820 820 820 810 820 - - t C [min] 30 30 30 30 60 30 - - T Sinter [°C] - - - - - - - - t Sinter [min] - - - - - - - - Fluorescent glass blue blue intense blue intense blue blue and white no blue blue Fluorescence glass ceramic blue blue intense blue pale blue blue and white no ** Comparison

Claims

1. Glass or glass ceramic with cerium and tin content, which comprise the following components: Componentwt.-%SiO259.0 to 80.0Al2O30.1 to 42.0Cerium, calculated as CeO20.5 to 10.0 4.0Tin, calculated as SnO0.1 toB2O30 to 5.0further oxide of tetravalentelements MeIVO20 to 4.0, wherein the term "further oxide of tetravalent elements MeIVO2" denotes tetravalent oxides with the exception of SiO2, CeO2, SnO2 and TiO2 and this MeIVO2 is selected in particular from ZrO2 and / or GeO2, and wherein the molar ratio of cerium, calculated as CeO2, to tin, calculated as SnO, lies in the range of from 10:1 to 1:1.

2. Glass or glass ceramic according to claim 1, which comprise 59.0 to 77.0, in particular 59.0 to 76.0, preferably 64.0 to 75.0 and particularly preferably 70.0 to 74.0 wt.-% SiO2.

3. Glass or glass ceramic according to claim 1 or 2, which comprise 0.3 to 39.0, in particular 0.5 to 30.0, preferably 1.0 to 20.0, particularly preferably 1.5 to 10.0 and most preferably 2.0 to 6.0 wt.-% Al2O3.

4. Glass or glass ceramic according to any one of claims 1 to 3, which comprise 0.7 to 7.5, in particular 1.0 to 7.0, preferably 1.5 to 5.0, and particularly preferably 2.0 to 4.0 wt.-% cerium, calculated as CeO2.

5. Glass or glass ceramic according to any one of claims 1 to 4, which comprise 0.2 to 3.0, in particular 0.3 to 2.0 and preferably 0.4 to 1.0 wt.-% tin, calculated as SnO.

6. Glass or glass ceramic according to any one of claims 1 to 5, in which the molar ratio of cerium, calculated as CeO2, to tin, calculated as SnO, lies in the range of from 5:1 to 1:1, preferably 3:1 to 1:1 and particularly preferably 2:1 to 1:1.

7. Glass or glass ceramic according to any one of claims 1 to 6, which comprise 0 to 2.0, in particular 0.05 to 1.5, preferably 0.1 to 1.0, and particularly preferably 0.3 to 0.7 wt.-% terbium, calculated as Tb4O7.

8. Glass or glass ceramic according to any one of claims 1 to 7, which comprise 0 to 18.0, in particular 1.0 to 17.0, preferably 3.0 to 16.0, and particularly preferably 7.5 to 10.0 wt.-% Li2O.

9. Glass or glass ceramic according to any one of claims 1 to 8, which comprise 0 to 10.0, in particular 0 to 5.0 and preferably 0 to 1.0 wt.-% BaO, and which are most preferably substantially free from BaO.

10. Glass or glass ceramic according to any one of claims 1 to 9, which comprise at least one and preferably all of the following components in the specified amounts: Componentwt.-%SiO259.0 to 77.0Al2O30.3 to 39.0Cerium, calculated as CeO20.7 to7.5Tin, calculated as SnO0.2 to 3.0Terbium, calculated as Tb4O70 to 2.0Li2O0 to 18.0MeI2O0 to 13.0 MeIIO0 to 22.0MeIII2O30 to 10.0MeIVO20 to 4.0MeV2O50 to 8.0MeVIO30 to 6.0Fluorine0 to5.0, wherein MeI2O is selected in particular from Na2O, K2O, Rb2O and / or Cs2O, MeIIO is selected in particular from MgO, CaO, SrO and / or ZnO, MeIII2O3 is selected in particular from B2O3, Y2O3, La2O3, Ga2O3 and / or In2O3, MeIVO2 is selected in particular from ZrO2 and / or GeO2, MeV2O5 is selected in particular from P2O5, V2O5, Ta2O5 and / or Nb2O5 and MeVIO3 is selected in particular from WO3 and / or MoO3.

11. Glass according to any one of claims 1 to 10, which comprises nuclei for the crystallization.

12. Glass or glass ceramic, which comprise the glass or the glass ceramic with cerium and tin content according to any one of claims 1 to 11, preferably in an amount of from 0.1 to 50 wt.-%, in particular 0.2 to 40 wt.-%, preferably 0.5 to 30 wt.-%, particularly preferably 1 to 20 wt.-% and more preferably 5 to 10 wt.-%.

13. Glass or glass ceramic according to any one of claims 1 to 12, wherein the glass and the glass ceramic are present in the form of a powder, a granulate, a blank or a dental restoration.

14. Process for the preparation of the glass or the glass ceramic according to any one of claims 1 to 13, in which the tin is used at least partially in divalent form and in particular as SnO.

15. Process for the preparation of the glass ceramic according to any one of claims 1 to 10, 12 and 13, in which the glass according to any one of claims 1 to 13 is subjected to at least one heat treatment at a temperature of from 700 to 950°C for a duration of in particular 5 to 120 min, preferably 10 to 60 min.

16. Process according to claim 15, in which (a) powder of the glass, optionally after the addition of further components, is pressed to form a powder compact, and (b) the powder compact is subjected to a heat treatment at a temperature of from 700 to 950°C, for a duration of in particular 5 to 120 min, or (a') melt of the glass is shaped to form a glass blank, in particular by pouring into a mould, and (b') the glass blank is subjected to a heat treatment at a temperature of from 700 to 900°C, for a duration of in particular 5 to 120 min.

17. Use of the glass or of the glass ceramic according to any one of claims 1 to 11 as blending component for setting the fluorescence of a glass or of a glass ceramic.

18. Use of the glass or of the glass ceramic according to any one of claims 1 to 13 as dental material and in particular for the preparation of dental restorations.

19. Use according to claim 18, wherein the glass or the glass ceramic is given the shape of the desired dental restoration, in particular inlay, onlay, crown, partial crown, bridge, veneer, facet or abutment, by pressing, sintering or machining, in particular in a CAD / CAM process.

20. Process for the preparation of a dental restoration, in particular inlay, onlay, crown, partial crown, bridge, veneer, facet or abutment, in which the glass or the glass ceramic according to any one of claims 1 to 13 is given the shape of the desired dental restoration by pressing, sintering or machining, in particular in a CAD / CAM process.