Lithium silicate glass ceramics comprising tin

Abstract

To provide lithium silicate glass ceramics containing tin, which are based on an acid-treated filler.SOLUTION: Lithium silicate glass ceramics and precursors thereof are described, which contain tin and are characterized by very good mechanical and optical properties and in particular can be used as restorative materials in dentistry. The lithium silicate glass ceramics according to the invention contain 0.01 to 4.5, preferably 0.03 to 3.0, particularly preferably 0.1 to 2.0, and most preferably 0.2 to 1.5 wt.% tin calculated as SnO2.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to lithium silicate glass ceramics containing tin, which are particularly suitable for use in dentistry, preferably for producing dental restorations, and to precursors for producing such glass ceramics. [Background technology]

[0002] Glass ceramics containing tin are known from the prior art.

[0003] European Patent Application Publication No. 1985591 describes glass ceramics that can be colored with metal colloids. Possible metal colloidal entities are compounds of the metals Au, Ag, As, Bi, Nb, Cu, Fe, Pd, Pt, Sb, and Sn. The glass ceramics are, in particular, lithium aluminosilicate glass ceramics or magnesium aluminosilicate glass ceramics containing a large amount of aluminum oxide in at least 18.0% by weight and significant amounts of antimony oxide and arsenic oxide which are harmful to health.

[0004] International Publication Nos. 03 / 050053 and 03 / 050051 describe antimicrobial glass ceramic powders that can be used in the field of dental care, for example, as components of mouthwash, toothpaste, or dental floss. To enhance antimicrobial properties, antimicrobially active ions such as Ag, Au, I, Ce, Cu, Zn, and Sn may be present. The glass ceramics have alkaline earth alkali silicates and / or alkaline earth silicates, particularly NaCa silicate and calcium silicate, as the main crystalline phase.

[0005] International Publication No. 2005 / 058768 discloses a lithium aluminosilicate glass ceramic body particularly suitable for the manufacture of cooking hobs. The body has a surface layer having a higher content of crystallization-promoting chemical elements from the group consisting of Zn, Cu, Zr, La, Nb, Y, Ti, Ge, V, and Sn. As the main crystalline phase, the glass ceramic contains a high-quartz solid solution phase.

[0006] European Patent Application Publication No. 1688397 describes lithium silicate glass ceramics containing a small amount of zinc oxide and a large amount of 2.0 to 5.0 wt% of a nucleating agent. The nucleating agent for forming lithium metasilicate is selected in particular from P2O5 and compounds of the elements Pt, Ag, Cu, and W, and is preferably P2O5. Thus, P2O5 is also used as a nucleating agent in all of the glass ceramics specifically disclosed, in addition to lithium silicate, and also results in the formation of lithium phosphate as a crystalline phase. However, lithium phosphate crystals may impair the mechanical and / or optical properties of the lithium silicate glass ceramic.

[0007] International Publication No. 2013 / 053866 describes lithium silicate glass ceramics containing tetravalent metal oxides such as tin oxide. Metals, particularly Ag, Au, Pt, and Pd, especially P2O5, are used as nucleating agents for the formation of lithium silicate. However, the use of P2O5 as a nucleating agent leads to the formation of lithium phosphate, which is undesirable as a crystalline phase. Furthermore, the glass ceramics contain only very small amounts of monovalent metal oxides K2O and Na2O, and preferably are substantially free of these metal oxides. European Patent Application Publication No. 3696149 describes fluorescent glass ceramics and glasses containing cerium and tin to produce fluorescence and P2O5 as a nucleating agent. In this context, tin is Ce 3+ and Ce 4+It helps to achieve the desired adjustment of the equilibrium with ions, thereby realizing the desired fluorescence and the desired discoloration of the glass-ceramic. The use of P2O5 as a nucleating agent may result in the presence of an undesirable phosphate crystal phase in the glass-ceramic.

Prior Art Documents

Patent Documents

[0008]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

Patent Document 6

Patent Document 7

Summary of the Invention

Means for Solving the Problems

[0009] In summary, known glass-ceramics do not possess the properties desirable for dental restorative materials or may result in the formation of undesirable crystal phases such as phosphate phases or cristobalite that can impair the mechanical and / or optical properties particularly desirable for restorative materials, and contain a large amount of P2O5.

[0010] Therefore, the present invention is based on the problem of providing a glass-ceramic having a very good combination of mechanical and optical properties. The glass-ceramic should also be easy to process into dental restorations and thus be excellently suitable as a restorative dental material.

[0011] This problem is solved by the lithium silicate glass ceramics described in claims 1 to 12 and 15. Similarly, the present invention is subject to the starting glass described in claims 13 to 15, the methods described in claims 16, 17, and 20, and the uses described in claims 18 and 19. This application provides, for example, the following items: (Reclaim) (Item 1) Lithium silicate glass ceramic containing 0.02 to 4.5, preferably 0.03 to 3.0, particularly preferably 0.1 to 2.0, and most preferably 0.2 to 1.5 wt% tin, calculated as SnO2. (Item 2) A glass ceramic according to any one of the above items, comprising 65.0 to 89.0, preferably 68.0 to 83.0, particularly preferably 75.0 to 81.0, and most preferably 77.0 to 80.0% by weight of SiO2. (Item 3) A glass ceramic according to any one of the above items, comprising 10.0 to 21.0, preferably 11.0 to 20.0, particularly preferably 13.0 to 19.0, and most preferably 14.0 to 18.0% by weight of Li2O. (Item 4) A glass ceramic according to any one of the above items, containing less than 3.0, preferably less than 2.0, particularly preferably less than 1.0, and most preferably less than 0.1% by weight of P2O5. (Item 5) 0 to 7.0, preferably 1.0 to 6.0 wt% of monovalent element oxides Me selected from K2O, Na2O, Rb2O, Cs2O, and mixtures thereof. I A glass ceramic containing 2O, as described in any one of the above items. (Item 6) A glass ceramic according to any one of the above items, comprising 0 to 6.0, preferably 1.0 to 5.0, more preferably 1.2 to 4.5, even more preferably 1.5 to 4.0, and most preferably 1.5 to 2.5% by weight of K2O. (Item 7) 0 to 15.0, preferably 0 to 10.0, and particularly preferably 0 to 8.0 wt% of divalent element oxides Me selected from the group consisting of CaO, MgO, SrO, ZnO, and mixtures thereof. II A glass ceramic containing O, as described in any one of the above items. (Item 8) Me2O3, a trivalent element oxide selected from Al2O3, B2O3, Y2O3, La2O3, and mixtures thereof, in a weight of 0 to 12.0, preferably 0.1 to 10.0, and particularly preferably 1.0 to 8.0% by weight. III A glass ceramic containing 2O3, as described in any one of the above items. (Item 9) A glass ceramic according to any one of the above items, comprising 0.1 to 6.0, preferably 1.0 to 5.0, more preferably 1.5 to 4.0, and most preferably 1.5 to 3.0 wt% Al2O3. (Item 10) A glass ceramic according to any one of the above items, comprising lithium disilicate or lithium metasilicate as the main crystalline phase, preferably lithium disilicate as the main crystalline phase. (Item 11) A glass ceramic according to any one of the above items, comprising 1.0 to 50.0% by weight, preferably 1.5 to 45.0% by weight, and particularly preferably 2.0 to 40.0% by weight of lithium metasilicate crystals. (Item 12) A glass ceramic according to any one of the above items, comprising 50.0 to 90.0, preferably 55.0 to 85.0, and particularly preferably 60.0 to 80.0% by weight of lithium disilicate crystals. (Item 13) A starting glass containing the glass-ceramic components described in any one of the above items. (Item 14) A starting glass according to any one of the above items, comprising a nucleus for crystallization of lithium metasilicate and / or lithium disilicate. (Item 15) The glass ceramic and the starting glass are in the form of a powder, granules, blank, or dental restoration, as described in any one of the items, the glass ceramic and the starting glass described in any one of the items. (Item 16) A method for producing a glass ceramic according to any one of the above items, comprising subjecting the starting glass according to any one of the above items to at least one heat treatment, particularly in the range of 800 to 1050°C, preferably 850 to 1020°C. (Item 17) (a) The starting glass is subjected to heat treatment at a temperature of 400 to 600°C, particularly 430 to 550°C, more preferably 440 to 520°C to form a starting glass with a nucleus. (b) The starting glass having the nucleus is subjected to heat treatment at a temperature of 800 to 1050°C, particularly 850 to 1020°C, to form a lithium silicate glass ceramic. A method using any one of the above items. (Item 18) The use of a glass ceramic or a starting glass as described in any one of the preceding items, preferably as a dental material for covering a dental restoration, and particularly preferably for producing a dental restoration. (Item 19) Use for producing any one of the items, wherein the glass ceramic or the starting glass is given the shape of a desired dental restoration, in particular a bridge, inlay, onlay, veneer, abutment, partial crown, crown, or facet, by pressing or machining. (Item 20) A method for producing dental restorations, particularly bridges, inlays, onlays, veneers, abutments, partial crowns, crowns, or facets, comprising pressing or machining a glass ceramic or starting glass described in any one of the preceding items to give the desired shape of the dental restoration, particularly in a CAD / CAM process. (Item 21) A composition comprising a glass ceramic as described in any one of the above items, or a starting glass as described in any one of the above items, which is used as a dental material, preferably for coating a dental restoration, and particularly preferably as a dental material for producing a dental restoration. (Item 22) A composition according to any one of the items for producing a dental restoration, wherein the glass ceramic or the starting glass is given the shape of a desired dental restoration, in particular a bridge, inlay, onlay, veneer, abutment, partial crown, crown, or facet, by pressing or machining. [Brief explanation of the drawing]

[0012] [Figure 1] The four small glass-ceramic plates obtained are shown. [Modes for carrying out the invention]

[0013] Lithium silicate glass ceramics and their precursors, which contain tin and are characterized by very good mechanical and optical properties, and can be used particularly as dental restorative materials, are described. The lithium silicate glass ceramic according to the present invention is characterized by containing 0.01 to 4.5, preferably 0.03 to 3.0, particularly preferably 0.1 to 2.0, and most preferably 0.2 to 1.5% by weight of tin, calculated as SnO2. Surprisingly, the glass ceramic according to the present invention exhibits a favorable combination of mechanical and optical properties desirable for restorative dental materials. The glass ceramic has high strength and fracture toughness, which allows for easy shaping of dental restorations, particularly through machining.

[0014] Surprisingly, the use of P2O5 as a conventional nucleating agent in lithium silicate glass ceramics is not necessarily required to achieve these properties. In the glass ceramics according to the present invention, it is assumed that the present tin acts as a nucleating agent. Furthermore, the fact that even small amounts of tin are effective is particularly surprising.

[0015] The glass ceramic according to the present invention may also have a very large amount of lithium silicate crystalline phase, for example, more than 65% by weight, and it is again assumed that the tin present as a nucleating agent is essentially responsible for this. Such high content lithium silicate crystalline phase is not normally possible to produce when P2O5 is used as a nucleating agent.

[0016] The glass ceramic according to the present invention preferably has only a very small amount of further crystalline phase, such as lithium phosphate or cristobalite. The formation of large amounts of such further crystalline phases frequently occurs with the use of large amounts of P2O5 as a nucleating agent, which has been common until now, and these further crystalline phases can have a negative effect on the mechanical and / or optical properties of the lithium silicate glass ceramic. Furthermore, lithium is consumed by the formation of lithium phosphate crystals and is therefore no longer available for the formation of lithium silicate. In particular, lithium silicate plays an essential role due to the excellent mechanical properties of lithium silicate glass ceramic. Therefore, the glass ceramic according to the present invention is advantageous in this respect as well.

[0017] The glass ceramic according to the present invention contains SiO2 in a particularly large amount of 65.0 to 89.0, preferably 68.0 to 83.0, most preferably 75.0 to 81.0, and most preferably 77.0 to 80.0% by weight.

[0018] The glass ceramic according to the present invention preferably further contains Li2O in an amount of 10.0 to 21.0, preferably 11.0 to 20.0, more preferably 13.0 to 19.0, and most preferably 14.0 to 18.0% by weight. Li2O is also assumed to lower the viscosity of the glass matrix and thus promote the crystallization of the desired crystal phase.

[0019] The glass ceramic preferably contains an oxide of a monovalent element, Me I 2O, selected from the group consisting of K2O, Na2O, Rb2O, Cs2O, and mixtures thereof, in an amount of 0 to 7.0, preferably 1.0 to 6.0% by weight.

[0020] The glass ceramic contains at least one, particularly all, of the following oxides of monovalent elements Me I 2O: [Table 2] <000… in the amounts shown is particularly preferred.

[0021] In a particularly preferred embodiment, the glass ceramic according to the present invention contains K2O in an amount of 1.0 to 5.0, preferably ......

[0022] Furthermore, the glass ceramic preferably contains an oxide of a divalent element, Me II O, selected from the group consisting of CaO, MgO, SrO, ZnO, and mixtures thereof, in an amount of 0 to 15.0, preferably 0 to 10.0, and most preferably 0 to 8.0% by weight.

[0023] In another preferred embodiment, the glass ceramic contains less than 2.0% by weight of BaO. In particular, the glass ceramic is substantially free of BaO.

[0024] Preferably, the glass ceramic contains at least one, particularly all, of the following oxides of divalent elements Me II O: [Table 3] It contains the amount shown.

[0025] A trivalent element oxide Me selected from the group consisting of Al2O3, B2O3, Y2O3, La2O3, and mixtures thereof, in an amount of 0 to 12.0, preferably 0.1 to 10.0, most preferably 1.0 to 8.0 wt% from Al2O3, B2O3, Y2O3, La2O3, and mixtures thereof. III Glass ceramics containing 2O3 are even more preferred.

[0026] Glass ceramics are oxides of the following trivalent elements: Me III At least one type of 2O3, especially all of them: [Table 4] It is particularly preferable to include the amount shown.

[0027] In a particularly preferred embodiment, the glass ceramic contains 0.1 to 6.0, preferably 1.0 to 5.0, more preferably 1.5 to 4.0, and most preferably 1.5 to 3.0 wt% Al2O3.

[0028] Furthermore, 0 to 9.0, particularly preferably 0 to 7.0 wt%, of tetravalent element oxides Me selected from the group consisting of ZrO2, TiO2, GeO2, and mixtures thereof. IV Glass ceramics containing O2 are preferred.

[0029] Particularly preferred is the glass ceramic being an oxide of the following tetravalent element Me IV At least one type of O2, especially all of them, [Table 5] It contains the amount indicated by [the symbol].

[0030] In another preferred embodiment, the glass ceramic contains 0 to 10.0, preferably 0 to 8.0 wt% of a pentavalent element oxide Me selected from the group consisting of Ta2O5, Nb2O5 and mixtures thereof. V Contains 2O5.

[0031] Particularly preferred is the glass ceramic being an oxide of the following pentavalent element Me V At least one type of 2O5, especially all of them: [Table 6] It contains the amount shown.

[0032] The glass ceramic according to the present invention may also preferably contain less than 3.0, preferably less than 2.0, more preferably less than 1.0, and most preferably less than 0.1% by weight of P2O5. In a further preferred embodiment, the glass ceramic is substantially free of P2O5.

[0033] In another embodiment, the glass ceramic contains 0 to 7.0, preferably 0 to 6.0 wt% of a hexavalent element oxide Me selected from the group consisting of WO3, MoO3, and mixtures thereof. VI Contains O3

[0034] Particularly preferred is the following oxide Me VI At least one type of O3, especially all of them: [Table 7] It contains the amount indicated by [the symbol].

[0035] In further embodiments, the glass ceramic according to the present invention contains 0 to 1.0, particularly 0 to 0.5% by weight of fluorine.

[0036] At least one, preferably all, of the following ingredients: [Table 8] (In the table, Me I 20, Me II O, Me III 203, Me IV O2, Me V 2O5, and Me VI O3 has the meaning given above. Glass ceramics containing the amount shown are particularly preferred.

[0037] In another particularly preferred embodiment, the glass ceramic comprises at least one, preferably all, of the following components: [Table 9] Contains in the indicated amount.

[0038] Some of the above components may act as colorants and / or fluorescent agents. The glass ceramics according to the present invention may further contain other colorants and / or fluorescent agents. These are in particular selected from further inorganic pigments and / or oxides of elements d and f, such as oxides of Mn, Fe, Co, Pr, Nd, Tb, Er, Dy, Eu, and Yb, or metals, preferably Ag, Cu, and Au.

[0039] In preferred embodiments of glass ceramics, the molar ratio of SiO2 to Li2O is in the range of 1.5 to 4.0, preferably 1.7 to 3.5, and more preferably 2.0 to 3.0.

[0040] The glass ceramic according to the present invention more preferably contains lithium disilicate or lithium metasilicate as the main crystalline phase, and more preferably lithium disilicate as the main crystalline phase.

[0041] The term "principal crystalline phase" refers to the crystalline phase that has the highest weight proportion of all crystalline phases present in the glass ceramic. The amount of the crystalline phase is determined, in particular, by the Rietveld method. A suitable procedure for quantitative analysis of the crystalline phase using the Rietveld method is described, for example, in the paper by M. Dittmer, “Glaser und Glaskeramiken im System MgO-Al2O3-SiO2mit ZrO2als Keimbildner”, University of Jena 2011.

[0042] The glass ceramic according to the present invention preferably contains at least 1.0% by weight, preferably at least 1.5% by weight, and particularly preferably at least 2.0% by weight of lithium metasilicate crystals. Particularly preferably, the glass ceramic according to the present invention contains 1.0 to 50.0% by weight, preferably 1.5 to 45.0% by weight, and particularly preferably 2.0 to 40.0% by weight of lithium metasilicate crystals.

[0043] In another embodiment, the glass ceramic according to the present invention preferably contains at least 50.0% by weight, preferably at least 55.0% by weight, and particularly preferably at least 60.0% by weight of lithium disilicate crystals. Particularly preferably, the glass ceramic according to the present invention contains 50.0 to 90.0% by weight, preferably 55.0 to 85.0% by weight, and particularly preferably 60.0 to 80.0% by weight of lithium disilicate crystals.

[0044] The glass ceramics according to the present invention are characterized in particularly good mechanical and optical properties and can be formed by heat treatment of a corresponding starting glass or a corresponding starting glass with a nucleus. Therefore, these materials serve as precursors to the glass ceramics according to the present invention.

[0045] The type and, in particular, the amount of the formed crystalline phase can be controlled by the composition of the starting glass and the heat treatment applied to produce glass ceramics from the starting glass. Examples demonstrate this by changing the composition of the starting glass and the heat treatment applied.

[0046] The glass ceramic has a high biaxial fracture strength, preferably at least 150 MPa, and particularly preferably at least 250 MPa. The biaxial fracture strength was determined according to ISO 6872 (2008) (piston-on-three-ball test).

[0047] The glass ceramic is preferably at least 1.5 MPa·m 0.5 Particularly preferably at least 2.0 MPa·m 0.5 Most preferably at least 2.5 MPa·m 0.5 It also possesses high fracture toughness. Fracture toughness was determined according to ISO 6872 (2015) (SEVNB method).

[0048] Furthermore, the glass ceramic is preferably 100 g / cm³ 2 It has high chemical stability, measured as acid solubility of less than ISO 6872 (2015).

[0049] The specific combination of properties present in the glass ceramic according to the present invention further enables its use as a dental material, particularly as a material for producing dental restorations.

[0050] The present invention also relates to precursors of corresponding compositions from which glass ceramics according to the present invention can be produced by heat treatment. These precursors are appropriately configured starting glass and starting glass having appropriately configured nuclei. The term "corresponding composition" means that these precursors contain the same composition as the glass ceramic in the same amounts, and the components are calculated as oxides, as is common in glass and glass ceramics, with the exception of fluorine.

[0051] Therefore, the present invention also relates to a starting glass containing the components of the glass ceramic according to the present invention.

[0052] Therefore, the starting glass according to the present invention particularly contains appropriate amounts of SiO2, Li2O, and tin, which are necessary for forming the glass ceramic according to the present invention. Furthermore, the starting glass may contain other components shown above with respect to the glass ceramic according to the present invention. All such embodiments are also preferred to the components of the starting glass that are shown to be preferred to the components of the glass ceramic according to the present invention.

[0053] It is particularly preferable that the starting glass takes the form of a monolithic blank obtained by casting the molten starting glass into a mold.

[0054] The present invention also relates to such starting glasses, which include nuclei for the crystallization of lithium silicate, particularly lithium metasilicate and / or lithium disilicate.

[0055] Starting glass is produced by melting a mixture of suitable starting materials, particularly carbonates, oxides, and halides, at a temperature of approximately 1500 to 1800°C for 0.5 to 4 hours. In particular, SnO or SnO2 can be used as a starting material for tin. The molten material can then be poured into water to produce frit. The resulting glass frit is melted again, especially to achieve high homogeneity.

[0056] Next, the molten material is poured into a mold to produce a blank of starting glass, also known as a solid glass blank or monolithic blank.

[0057] A further precursor starting glass with nuclei can be initially produced by heat treatment of the starting glass. Then, the lithium silicate glass ceramic according to the present invention can be produced by heat treatment of this further precursor. Alternatively, the glass ceramic according to the present invention can be formed by heat treatment of the starting glass.

[0058] It is preferable to subject the starting glass to a heat treatment at a temperature of 400 to 600°C, particularly 430 to 550°C, and especially preferably 440 to 520°C, for a duration of 5 to 120 minutes, particularly 10 to 60 minutes, in order to produce a starting glass with nuclei for the crystallization of lithium silicate.

[0059] It is even more preferable to subject the starting glass or starting glass with a nucleus to a heat treatment at a temperature of 800 to 1050°C, preferably 850 to 1020°C, particularly for a duration of 5 seconds to 120 minutes, preferably 1 minute to 100 minutes, more preferably 5 minutes to 60 minutes, and even more preferably 10 minutes to 30 minutes, in order to produce the glass ceramic according to the present invention.

[0060] Accordingly, the present invention also relates to a method for producing glass ceramics according to the present invention, comprising subjecting a starting glass or a starting glass having a nucleus to at least one heat treatment in the range of 800 to 1050°C, preferably 850 to 1020°C, for a duration of 5 seconds to 120 minutes, preferably 1 minute to 100 minutes, more preferably 5 minutes to 60 minutes, and even more preferably 10 minutes to 30 minutes.

[0061] At least one heat treatment carried out by the method according to the present invention may also be carried out in the process of hot pressing of a starting glass according to the present invention or a starting glass according to the present invention having a nucleus, in particular of a solid glass blank, or in particular of a powder sintering process.

[0062] In a further preferred embodiment, the starting glass or starting glass with a nucleus can first be subjected to a heat treatment at a temperature of 550 to 800°C, preferably 600 to 800°C, for a duration of 5 seconds to 120 minutes, preferably 1 minute to 100 minutes, most preferably 5 minutes to 60 minutes, and even more preferably 10 minutes to 30 minutes, in order to produce the glass ceramic according to the present invention having lithium metasilicate as the main crystalline phase.

[0063] Next, the glass ceramic according to the present invention, having lithium metasilicate as the main crystalline phase, can be subjected to further heat treatment to convert the lithium metasilicate crystals into lithium disilicate crystals, and in particular, the glass ceramic according to the present invention having lithium disilicate as the main crystalline phase can be formed. Preferably, the glass ceramic is subjected to further heat treatment at a temperature of 800 to 1050°C, preferably 850 to 1020°C, particularly preferably 900 to 1020°C, for a duration of particularly 5 seconds to 120 minutes, preferably 1 minute to 100 minutes, particularly preferably 1 minute to 60 minutes, even more preferably 5 to 30 minutes, and most preferably 5 to 20 minutes.

[0064] The conditions suitable for a given glass ceramic can be determined, for example, by performing X-ray diffraction analysis at various temperatures.

[0065] The glass ceramics and glass according to the present invention exist, in particular, in the form of powders, granules, or blanks of any shape and size, such as monolithic blanks, such as plates, cuboids, or cylinders, or in the form of powder compressions, in an unsintered, partially sintered, or densely sintered form. In these forms, they can be easily further processed, for example, into dental restorations. However, they can also take the form of dental restorations such as inlays, onlays, crowns, veneers, facets, or abutments.

[0066] Dental restorations, such as bridges, inlays, onlays, crowns, veneers, facets, or abutments, can be produced from glass ceramics and glass according to the present invention. Therefore, the present invention also relates to their use in the production of dental restorations. In this context, it is preferable that the glass ceramic or glass be given the shape of the desired dental restoration by pressing, particularly by machining.

[0067] Pressing is typically carried out under increased pressure and temperature. Pressing is preferably carried out at a temperature of 700 to 1200°C. Pressing is even more preferably carried out at a pressure of 2 to 10 bar. During pressing, the desired change in shape is achieved by the viscous flow of the material used. Starting glass according to the present invention, starting glass with a nucleus according to the present invention, and glass ceramics according to the present invention can be used for pressing. In particular, the glass and glass ceramics according to the present invention can be used in the form of blanks of any shape and size.

[0068] Machining is typically carried out by a material removal process, particularly by milling and / or grinding. Machining is particularly preferably carried out by a CAD / CAM process. Starting glass, nucleated starting glass, and glass ceramic according to the present invention can be used for machining. Preferably, nucleated starting glass or glass ceramic according to the present invention, having lithium metasilicate as the main crystalline phase, is used. In this context, glass and glass ceramic according to the present invention can be used in particular in the form of blanks.

[0069] Due to the aforementioned properties of the glass ceramics and glass according to the present invention, they are particularly suitable for use in dentistry. Therefore, an object of the present invention is also to use the glass ceramics or glass according to the present invention as dental materials, preferably to produce dental restorations such as bridges, inlays, onlays, veneers, abutments, partial crowns, crowns, or facets.

[0070] Therefore, the present invention also relates to a method for producing dental restorations, particularly bridges, inlays, onlays, veneers, abutments, partial crowns, crowns, or facets, wherein the desired shape of the dental restoration is given to glass ceramic or glass according to the present invention by pressing or machining, particularly by a CAD / CAM process.

[0071] The present invention will be described in more detail below using non-limiting embodiments. [Examples]

[0072] (Examples 1 to 49 - Composition and Crystalline Phases) A total of 49 types of glass and glass ceramics according to the present invention, having the compositions shown in Table 1, were produced by melting the corresponding starting materials to produce the starting glass, followed by a heat treatment to control crystallization.

[0073] The applied heat treatment and the properties of the resulting glass ceramic are shown in Table 1. The following meanings apply. T g Glass transition temperature determined by DSC T s and t s Temperature and time applied to melt the starting glass T Kb and t Kb Temperature and time applied for nucleation of the starting glass T C1 and t C1 Temperature and time applied for the first crystallization T C2 and t C2 Temperature and time applied for the second crystallization K IC Fracture toughness measured according to ISO 6872 (2015) (SEVNB method) Chemical stability was measured as mass loss according to ISO 6872 (2015). σ Biax Biaxial fracture strength measured according to ISO 6872 (2015) (piston-on-three-ball test)

[0074] In the examples, starting glass having the composition shown in Table 1 was first prepared from common raw materials in quantities of 100 to 200 g, T S At the temperature t sThe melting occurred over the duration of the temperature, and very good melting was possible without bubbles or streaks. Glass frit was prepared by pouring the starting glass into water, and if necessary, a second melting was performed at temperature T s de t s This process was carried out over a specified duration to homogenize the material. The resulting molten material from the starting glass was then poured into a graphite mold to produce a monolithic glass block.

[0075] The temperature of the obtained glass block, T Kb Duration t Kb The first heat treatment over a certain temperature resulted in the relaxation of the glass and the formation of nucleated glass. These nucleated glasses were formed at temperature T C1 Duration t C1 Further heat treatment by [method] crystallized, forming a glass ceramic having lithium metasilicate or lithium disilicate as the main crystalline phase, as determined by X-ray diffraction studies at room temperature. In some cases, temperature T C2 Duration t C2 Further heat treatment was carried out to obtain a glass ceramic having lithium disilicate as the main crystalline phase.

[0076] In Examples 9 and 38, glass frit was produced by pouring the starting glass into water. These frits were crushed, sieved, and subsequently sintered at the temperatures and times shown in Table 1.

[0077] The amount of the crystalline phase was determined by X-ray diffraction. For this purpose, each glass-ceramic powder was prepared by grinding and sieving (<45 μm) and mixed with Al2O3 (Alfa Aesar, product number 42571) as an internal standard in a ratio of 80 wt% glass-ceramic to 20 wt% Al2O3. The mixture was slurryed with acetone to achieve the best possible mixture. The mixture was then dried at approximately 80°C. Diffraction maps were then recorded using a Bruker D8 Advance diffractometer with CuKα radiation and a step size of 0.014°2θ in the range of 10 to 100°2θ. These diffraction maps were then analyzed using Bruker's TOPAS 5.0 software with the Rietveld method. The proportion of each phase was determined by comparing the peak intensity with the Al2O3 intensity.

[0078] To determine the biaxial fracture strength according to ISO 6872(2015) (piston-on-three-ball test), holders were bonded to blocks of relaxed and nucleated glass, and these blocks were subsequently machined using a CAD / CAM grinding unit (Sirona InLab). The grinding process was carried out using diamond-coated grinding tools. The resulting plates were subjected to the heat treatments shown in the table, namely, first crystallization and, if necessary, second crystallization, and the crystallized plates were then polished to a thickness of 1.2 ± 0.2 mm using a diamond wheel. The biaxial fracture strength was determined for the test specimens thus prepared.

[0079] High biaxial fracture strengths ranging from over 179 to 524 MPa were determined for the generated glass ceramics.

[0080] Fracture toughness was determined according to ISO 6872 (2015) (SEVNB method), ranging from 2.6 to 3.1 MPa·m. 0.5 High fracture toughness in the specified range was determined for the produced glass ceramics.

[0081] Chemical stability testing was conducted according to ISO 6872 (2015), and the resulting glass ceramic was 100 g / cm³. 2 It showed an acid solubility of less than [value missing].

[0082] Dental crowns were fabricated from the generated glass and glass ceramic materials using CAD / CAM-assisted machining, and these crowns were subjected to final crystallization under the conditions shown in Table 1 as needed.

[0083] (Example 50 - Comparison) In this example, a tin-free starting glass was prepared by melting the corresponding starting material, and this glass was subsequently heat-treated to crystallize it.

[0084] The manufacturing method was the same as that described for the preparations of Examples 1 to 49. The composition used, the heat treatment applied, and the properties of the resulting glass ceramics are also shown in Table 1.

[0085] Figure 1 shows four small plates of the obtained glass ceramic. In these tin-free samples, cracks can be seen due to uncontrolled crystal growth. [Table 1-1] [Table 1-2] [Table 1-3] [Table 1-4] [Table 1-5]

Claims

1. SnO ２ % tin, calculated as 0.02 to 4.5, preferably 0.03 to 3.0, particularly preferably 0.1 to 2.0, most preferably 0.2 to 1.5 wt. % tin.

2. 65.0 to 89.0, preferably 68.0 to 83.0, particularly preferably 75.0 to 81.0, most preferably 77.0 to 80.0 wt. % SiO ２ 2. The glass-ceramic of claim 1, comprising:

3. 10.0 to 21.0, preferably 11.0 to 20.0, particularly preferably 13.0 to 19.0, most preferably 14.0 to 18.0 wt. % Li ２ 2. The glass-ceramic of claim 1 , comprising O.

4. less than 3.0, preferably less than 2.0, particularly preferably less than 1.0, most preferably less than 0.1 wt. % P ２ O ５ 2. The glass-ceramic of claim 1, comprising:

5. 0 to 7.0, preferably 1.0 to 6.0 wt. % K ２ O, Na ２ O, Rb ２ O, Cs ２ Oxides of monovalent elements selected from the group consisting of O, and mixtures thereof. Ｉ ２ 2. The glass-ceramic of claim 1 , comprising O.

6. 0 to 6.0, preferably 1.0 to 5.0, more preferably 1.2 to 4.5, even more preferably 1.5 to 4.0, and most preferably 1.5 to 2.5 wt. % K ２ 2. The glass-ceramic of claim 1 , comprising O.

7. 0 to 15.0, preferably 0 to 10.0, particularly preferably 0 to 8.0 wt. % of oxides of divalent elements selected from the group consisting of CaO, MgO, SrO, ZnO, and mixtures thereof, Me ＩＩ 2. The glass-ceramic of claim 1 , comprising O.

8. 0 to 12.0, preferably 0.1 to 10.0, particularly preferably 1.0 to 8.0 wt. % Al ２ O ３ , B ２ O ３ , Y ２ O ３ , La ２ O ３ and mixtures thereof. ＩＩＩ ２ O ３ 2. The glass-ceramic of claim 1, comprising:

9. 0.1 to 6.0, preferably 1.0 to 5.0, more preferably 1.5 to 4.0, and most preferably 1.5 to 3.0 wt. % Al ２ O ３ 2. The glass-ceramic of claim 1, comprising:

10. 2. The glass-ceramic according to claim 1, comprising lithium disilicate or lithium metasilicate as the predominant crystalline phase, preferably lithium disilicate as the predominant crystalline phase.

11. 2. The glass-ceramic according to claim 1, comprising 1.0 to 50.0 wt. %, preferably 1.5 to 45.0 wt. %, particularly preferably 2.0 to 40.0 wt. % of lithium metasilicate crystals.

12. 2. The glass-ceramic according to claim 1, comprising 50.0 to 90.0, preferably 55.0 to 85.0, particularly preferably 60.0 to 80.0 wt.-% lithium disilicate crystals.

13. A starting glass comprising the components of a glass-ceramic according to any one of claims 1 to 9.

14. 14. The starting glass of claim 13, comprising nuclei for the crystallization of lithium metasilicate and / or lithium disilicate.

15. 13. The glass ceramic according to claim 1 or the starting glass comprising components of the glass ceramic according to claim 1, wherein the glass ceramic and the starting glass are in the form of a powder, granules, a blank, or a dental restoration.

16. 13. A method for producing a glass ceramic according to any one of claims 1 to 12, comprising subjecting a starting glass comprising the components of a glass ceramic according to any one of claims 1 to 9 to at least one heat treatment, in particular in the range of 800 to 1050°C, preferably 850 to 1020°C.

17. (a) subjecting the starting glass to a heat treatment at a temperature of from 400 to 600°C, in particular from 430 to 550°C, more preferably from 440 to 520°C, to form a nucleated starting glass; (b) subjecting the starting glass with said nuclei to a heat treatment at a temperature of 800 to 1050°C, in particular 850 to 1020°C, to form a lithium silicate glass ceramic; 17. The method of claim 16.

18. 13. Use of a glass ceramic according to any one of claims 1 to 12 or of a starting glass comprising components of a glass ceramic according to any one of claims 1 to 9 as a dental material, preferably for coating dental restorations, particularly preferably for producing dental restorations.

19. 19. Use for producing a dental restoration according to claim 18, wherein the glass ceramic or the starting glass is given the shape of the desired dental restoration, in particular a bridge, an inlay, an onlay, a veneer, an abutment, a partial crown, a crown or a facet, by pressing or machining.

20. 13. A method for producing a dental restoration, in particular a bridge, inlay, onlay, veneer, abutment, partial crown, crown or facet, comprising giving a glass ceramic according to any one of claims 1 to 12 or a starting glass comprising components of a glass ceramic according to any one of claims 1 to 9 the shape of the desired dental restoration by pressing or machining, in particular in a CAD / CAM process.

21. 13. A composition comprising a glass ceramic according to any one of claims 1 to 12 or a starting glass comprising components of a glass ceramic according to any one of claims 1 to 9, for use as a dental material, preferably for coating dental restorations, particularly preferably for producing dental restorations.

22. 22. A composition according to claim 21 for producing a dental restoration, wherein the glass ceramic or the starting glass is given the shape of a desired dental restoration, in particular a bridge, an inlay, an onlay, a veneer, an abutment, a partial crown, a crown or a facet, by pressing or machining.

Images