Dental Multicolor Blanks

Abstract

The present invention relates to a dental blank having first and second layers, each independently based on glass, glass ceramic, or ceramic, wherein the first and second layers are different in color and form an interface that runs obliquely. In this context, the term "based on" means that the first and second layers of the blank contain primarily glass, glass ceramic, or ceramic, relative to the total weight of all components of the layers. Preferably, the first and second layers are, independently of each other, made of glass, glass ceramic, or ceramic.

Description

[Technology Field]

[0001] The present invention relates to a dental blank that can very well mimic the optical properties of natural tooth material and, due to these properties, has very good mechanical properties, and is particularly suitable for the simple production of dental restorations with strict aesthetic requirements. [Background technology]

[0002] Developing blanks that meet diverse requirements for use in the field of dental technology is a major challenge. Such blanks must not only be easy to produce, but also easily molded to the desired shape and dimensions while still producing high-strength restorations. Finally, the blanks must already possess an appearance similar to that of natural tooth material, thus eliminating the need for complex veneering of subsequent restorations.

[0003] The use of multicolor blocks to reproduce the color and translucency gradient from dentin to tooth enamel, and their application in dental technology, is known from the latest technology. For example, EP 0 870 479 A2 describes a method for producing multicolor molded bodies to be further processed into dental restorations, comprising filling a press die with at least two different colored starting materials in the form of powders or granular materials and pressing them to form multicolor molded bodies.

[0004] In the case of such molded bodies, also called sintered blocks due to their conventional further sintering process, color gradients can be achieved relatively simply by sequentially introducing different colored starting materials into the extrusion die. However, to mimic the color and translucency gradients of natural teeth as accurately as possible, it is usually necessary to layer more than two layers. Furthermore, in the case of uniaxially pressed blocks, two or more layers can usually only be pressed in substantially horizontal layers. This has the further disadvantage that, in the case of separated layers, their interfaces remain visible in the final restoration. In the case of molar replacement, it is usually necessary to layer at least three layers to reproduce the natural color and translucency gradients. Basically, the following applies: the interfaces between layers are not very noticeable, and more layers are stacked on top of each other. Therefore, in the case of sintered blocks, it is generally necessary to make the transitions continuous, at least from the dentin to the incisal edge, in order to completely eliminate the transitions between individual layers. However, this typically requires complex filling devices, as described in WO2013 / 067994A1, for example.

[0005] The above method for producing uniaxially pressed sintered blocks allows for very good imitation of molars. However, reproducing anterior teeth is generally more difficult because the horizontally stacked blocks are not constructed like natural anterior teeth, where a translucent enamel layer covers a darker dentin core substantially across the entire tooth in the cervical-incisal direction.

[0006] Therefore, in addition to the substantially horizontal arrangement of layers of different colors, blocks in which the interfaces between layers of different colors take the shape of a parabola are also known. For example, WO2015 / 051095A1 describes its use for the production of such blanks and dentures.

[0007] However, in the case of multi-color blocks of known powder or granular material layers, such as zirconium oxide blocks, a sintering step is still required after the molding of the dental restoration to achieve the high strength essential for dental restorations, independently of the boundary layer trajectories between individual layers. However, this sintering involves significant shrinkage, which must be taken into consideration by the use of complex expansion molds. As a result, fit problems can arise as a result of the sintering process.

[0008] To avoid potential fit problems, in addition to sintered blocks, glass and glass-ceramic blocks, as well as their use for the production of dental restorations, are also generally known. These are produced by solid glass technology, i.e., by melting suitable starting components, casting the molten material in a suitable mold, and then heat-treating it as needed. In the case of these blocks, the post-molding sintering step can be omitted. However, such glass-ceramic blocks, such as lithium silicate glass-ceramic blocks, are usually monochromatic, and as a result, when used by dental technicians in the anterior tooth region, laminated materials must be added to mimic the natural tooth color gradient as well as possible. Adding laminated materials is a complex and costly process. Furthermore, the mechanical properties of laminated materials, such as strength, are generally lower than those of framework materials, and as a result, laminated materials often cause clinical defects in dental restorations. Therefore, a homogeneous monolithic high-strength glass-ceramic material, in which the dentin and incisal regions are made of the same material except for color and translucency, is generally desirable.

[0009] Solid glass blocks with glass layers of different colors can certainly be produced in different ways. For example, WO2014 / 124879A1 describes dental blanks having two or more layers of lithium silicate glass or lithium silicate glass ceramic of different colors, which can be obtained by bonding a monolithic layer in the form of a molten material to another monolithic layer of a different color. However, in the case of solid glass blocks, it is generally necessary to bond a very large number of layers, such as eight or more, to each other in order to achieve an apparent continuous gradient of color and translucency.

[0010] Therefore, in the case of known multicolor blanks, the use of multiple layers of different colors, or even a continuous color gradient, is necessary to mimic the color and translucency gradient of natural teeth as faithfully as possible and to avoid visible interfaces between individual layers. However, creating multiple layers of different colors is complex and not very economical, especially in the case of blocks produced by solid glass technology. In the case of multicolor blanks made from powder or granular material layers, so-called sintered blocks, there is a further problem that the necessary sintering can lead to fit issues after the dental restoration has been formed. Dental restorations produced from sintered blocks also generally have lower strength. [Prior art documents] [Patent Documents]

[0011] [Patent Document 1] European Patent Application Publication No. 0870479 [Patent Document 2] International Publication No. 2013 / 067994 [Patent Document 3] International Publication No. 2015 / 051095 [Patent Document 4] International Publication No. 2014 / 124879 [Overview of the Initiative] [Means for solving the problem]

[0012] According to the present invention, the above-mentioned problems are avoided. In particular, the object of the present invention is to provide a blank that is simple to produce and can be used to very well imitate the appearance of natural tooth material, can be simply given the shape of a desired dental restoration by machining, and can be converted after molding into a precise and high-strength dental restoration in which the interface between different layers is not visible, without substantial shrinkage.

[0013] This objective is achieved by the blanks described in claims 1 to 18. The subject of the present invention is also a method for producing the blanks described in claims 19 to 21, a method for producing dental restorations described in claims 22 to 26, and the use of the blanks described in claim 27.

[0014] The dental blanks according to the present invention are independent of each other, glass, Glass ceramic, or ceramic It has first and second layers based on, The first and second layers are characterized by having different colors, forming an interface, and the interface extending diagonally.

[0015] In relation to the above, the term "based on" means that the first and second layers of the blank mainly contain glass, glass ceramic, or ceramic, relative to the total mass of all constituent components of the layers. Preferably, the first and second layers consist of glass, glass ceramic, or ceramic independently of each other.

[0016] Preferably, both the first and second layers are glass-based, glass-ceramic-based, or ceramic-based. More preferably, both the first and second layers are made of glass, glass-ceramic, or ceramic.

[0017] "Difference in color" means a difference in color tone in the narrow sense and / or a difference in translucency, opalescence or fluorescence. The term "translucency" describes the light transmittance. Color can be characterized in particular by its Lab values or by the shade guides customary in the dental industry. Furthermore, the difference in color between the first and second layers of the blank does not necessarily have to be recognizable to the human eye. Rather, the difference in color tone and / or translucency may only become visually recognizable for the first time after the sintering step or heat treatment.

[0018] Thus, the blank according to the invention is characterized in particular in that the desired color gradient is already provided by only two different-colored layers, and as a result, the color and translucency gradient of natural teeth, particularly front teeth, can be mimicked in the subsequent denture without the interfacial boundary between the layers being visible. This is surprisingly achieved, unlike in the case of a uniaxially pressed sintered block, by the interfacial boundary between the first and second layers extending obliquely rather than horizontally. This makes it possible to obliquely arrange a more translucent layer intended to mimic the incisal layer above a more opaque and darker-colored layer intended to mimic the dentin layer, and as a result, the color gradient of natural teeth, particularly front teeth, can be mimicked without the dividing boundary line between the layers being recognizable and the transition appearing continuous.

[0019] According to the invention, the presence of further layers is not excluded. However, the fewer layers the blank contains, the less laborious the preparation for the production of the blank becomes. Therefore, the blank according to the invention preferably does not have any further layers in addition to the first and second layers.

[0020] Preferably, the volume regions formed by the first and second layers are non-concentric. This means that these volume regions of the blank do not have the same center of gravity.

[0021] In a first cross-sectional plane passing through the blank and extending parallel to the insertion axis of the blank, it is even more preferable that the interfacial boundary between the first and second layers does not extend perpendicular to the insertion axis.

[0022] The term "insertion axis of the blank" refers to the axis in the cervical-incisal direction, and in particular, with respect to the case where the crown is produced from the blank, it describes the insertion direction with respect to the model of the denture produced from the blank. Thus, generally, the insertion axis of the blank substantially coincides with the longitudinal axis of the teeth of the denture produced therefrom. Thus, the insertion axis refers to the condition of each patient. In the case of a blank in the form of a block or cube, the insertion axis preferably becomes a straight line passing through the center of gravity of two opposing side surfaces of the blank, particularly two side surfaces opposing in the cervical-incisal direction. In the case of a blank in the form of a disc or cylinder, the insertion axis preferably extends perpendicular to the surface of the disc. According to one embodiment, when the blank has a holder of a processing device such as a holder of a CAD / CAM device, as described in more detail below, the insertion axis of the blank preferably extends perpendicular to the rotation axis of the holder.

[0023] In particular, it is preferable that the boundary surface of the first cross-sectional plane extends substantially straight. Thus, in a preferred embodiment, the blank according to the present invention is characterized in that the boundary surface between the first and second layers in the first cross-sectional plane extends substantially straight and is at an angle different from 90° with respect to the insertion axis.

[0024] Particularly preferred is a blank in which the boundary surface between the first and second layers in the first cross-sectional plane is at an angle of 20 to 80°, preferably 30 to 80°, with respect to the insertion axis. In the case of the locus of such a boundary surface, the natural color gradient of the front teeth can be particularly well mimicked.

[0025] In another embodiment, the boundary surface between the first and second layers in the first cross-sectional plane extends in an arc shape. Also in this embodiment, it is preferable that the boundary surface between the first and second layers in the first cross-sectional plane is at an angle different from 90° with respect to the insertion axis of the blank. Particularly preferably, the best-fit line passing through the line of the boundary surface in the first cross-sectional plane is at an angle of 20 to 80°, preferably 30 to 80°, with respect to the insertion axis of the blank so that the color gradient of the front teeth can be particularly well mimicked.

[0026] Regardless of whether the interface between the first and second layers in the first cross-sectional plane extends substantially straight or in an arc, the blank has first and second regions, the first region located on one side of the interface, e.g., above the interface, and acting to mimic the incisal edge of a tooth in a dental restoration produced from the blank, and the second region located on the opposite side of the interface, e.g., below the interface, and acting to mimic the dentin of a tooth in a dental restoration produced from the blank.

[0027] Furthermore, the axis of rotation of the blank is preferably substantially perpendicular to the insertion axis of the blank. Particularly preferably, the angle between the axis of rotation and the insertion axis in the first cross-sectional plane is 90°. In further embodiments, the angle between the axis of rotation and the insertion axis in the first cross-sectional plane is preferably 70–110°, particularly 80–100°, and particularly preferably about 90°. The term “axis of rotation of the blank” refers to the axis that is the center of rotation of the blank during machining for forming the desired dental restoration. If the blank has, for example, a holder for a CAD / CAM device, the axis of rotation of the blank coincides with the axis of rotation of the holder.

[0028] Therefore, a blank is preferred in which the interface between the first and second layers in the first cross-sectional plane is at an angle of 10 to 70°, preferably 10 to 60°, with respect to the axis of rotation. It has been found that such an angle between the interface between the first and second layers and the axis of rotation provides greater freedom in the design and placement of dental restorations on the blank, and as a result, complex 5-axis machining of the blank can be avoided.

[0029] Furthermore, the interface between the first and second layers extends in an arc shape, and more preferably, it curves convexly through a blank in the second cross-sectional plane that extends perpendicular to the first cross-sectional plane. The term “convexly curved” refers to the layer that is less translucent and therefore intended to mimic the dentin layer of the tooth being replaced. This means that the less translucent layer curves “outward” in the second cross-sectional plane, i.e., towards the more translucent layer. Also, the interface of this orbit between the first and second layers allows for particularly good mimicry of the natural color gradient of the anterior teeth. In particular, when reproducing anterior tooth crowns, the convex curvature with respect to the dentin layer allows for an apparent continuous transition between the dentin and the incisal edge, not only incisally but also mesially and distally.

[0030] In natural anterior teeth, the dentin in the incisal region protrudes with an incisal tubercle structure. Therefore, in order to particularly faithfully mimic anterior teeth, in the case of blanks according to the present invention, it is preferable that the interface between the first and second layers in the second cross-sectional plane has an incisal tubercle structure. The term "incisal tubercle" refers to a small projection or bump. Therefore, an incisal tubercle structure has a depression. In particular, it is advantageous that the incisal tubercle protrudes toward the cervical direction. Furthermore, it is advantageous that the incisal tubercle tapers toward the incisal edge. Therefore, according to a preferred embodiment, in the second cross-sectional plane, the interface preferably has a plurality of depressions, starting from its generally convex curved trajectory. Preferably, the depressions differ in width and depth from one another, and as a result, it is preferable that an irregular incisal tubercle structure exists. Furthermore, the incisal tubercle structure is preferably designed such that the depth of the depressions is 2 mm or less, preferably 0.1 to 0.5 mm. In one embodiment, the depth of one or all of the incisal tubercle structures is not constant and decreases along the spread of the interface perpendicular to the second cross-sectional plane. When the blank according to the present invention is used to manufacture a crown for the restoration of an anterior tooth, the interface preferably has two or three incisal tubercles.

[0031] Furthermore, a blank in which the first layer has a refractive index that differs from that of the second layer by 0.1 or less is preferred. This embodiment has the particular advantage that the interlayer separation interface is not visually perceptible. The refractive index may be determined by immersion using a refractive index solution or by a so-called Abbe refractometer. In the case of a blank based on lithium silicate glass ceramic, the above preferred difference between the refractive indices of the first and second layers is related to the lithium disilicate state, i.e., after heat treatment to form lithium disilicate, the refractive index of the first layer differs from that of the second lithium disilicate layer by 0.1 or less. As is known to those skilled in the art, the refractive index of glass or glass ceramic depends on its chemical composition and / or the crystalline phases that may exist. For example, an increase in the proportion of SiO2 in a glass based on SiO2 / CaO / MgO / Na2O / Al2O3 / K2O results in a decrease in the refractive index.

[0032] Furthermore, it is preferable that the blank according to the present invention has a mark that can be recognized by a CAD / CAM device, and that the position of the interface between the first and second layers can be determined with an accuracy of 0.1 mm in particular. The design of such a mark can be freely selected. For example, the mark may be in the form of a notch or projection and be applied to the edge or side of the blank. According to one embodiment, the mark is a notch applied directly to the interface between the first and second layers. Alternatively, the notch may be spaced away from the interface. In this regard, for example, in order to achieve a desired ratio of dentin to incisal layer, the reproducibility of the distance of the notch from the interface is important so that the restoration is placed at an accurate distance from the interface by the CAD / CAM device. During machining of the blank, the mark in the form of a notch can be recognized by a tactile method. In the case of the mark in the form of an engraving or colored mark, the mark can be captured by a camera or scanner. The description of the position of the interface between the first and second layers in relation to the mark can also be incorporated into a scannable QR code® or data matrix code. CAD / CAM equipment can calculate the optimal position of the restoration on the blank. Alternatively, especially if the trajectory of the layers on the blank is represented in the CAD software, the user can also manually move the position of the restoration to the desired area of ​​the blank using the CAD software.

[0033] In a particularly preferred embodiment, the blank according to the present invention has a combination of two or more of the preferred features described above. In particular, the blank is - The interface between the first and second layers in the first cross-sectional plane extends substantially straight or in an arc, at an angle different from 90° with respect to the insertion axis, and the angle of the best fit line passing through the interface in the first cross-sectional plane or the trajectory of the interface with respect to the insertion axis in the first cross-sectional plane is 20 to 80°, preferably 30 to 80°. - The axis of rotation of the blank in the first cross-sectional plane extends substantially perpendicular to the insertion axis, and the angle between the axis of rotation and the insertion axis in the first cross-sectional plane is preferably 70 to 110°, particularly 80 to 100°, and particularly preferably 90°. - The interface between the first and second layers in the first cross-sectional plane extends substantially straight or in an arc, at an angle different from 90° with respect to the axis of rotation, and the angle of the best fit line passing through the interface in the first cross-sectional plane or the trajectory of the interface with respect to the axis of rotation in the first cross-sectional plane is 10 to 70°, preferably 10 to 60°. - The interface between the first and second layers extends in an arc shape, and in particular, curves convexly through a blank in the second cross-sectional plane that extends perpendicular to the first cross-sectional plane. - The interface between the first and second layers in the second cross-sectional plane has a cut edge knot structure, and the cut edge knot structure is preferably designed such that, in at least a portion of the interface, the depth of the indentation of the cut edge knot structure is 2 mm or less, preferably 0.1 to 0.5 mm. - The first layer has a refractive index that differs from the refractive index of the second layer by 0.1 or less, and - The blank according to the present invention has markings that can be recognized by a CAD / CAM device, and the position of the interface between the first and second layers can be determined with an accuracy of 0.1 mm in particular. It is characterized by the following. [Brief explanation of the drawing]

[0034] [Figure 1] For example, Figure 1 shows a schematic diagram of a multicolor blank 1 according to the present invention, having a first layer 3 and a second layer 5 of different colors that form an interface 7. The interface 7 extends in a first cross-sectional plane parallel to the insertion axis 8 and is represented in Figure 1 as a side surface 15 of the blank formed by edges 11 and 13 at an angle 16 with respect to the insertion axis 8. The insertion axis 8 in the first cross-sectional plane 15 extends perpendicular to the rotation axis 9 of the blank. The interface 7 in the first cross-sectional plane 15 extends at an angle 17 with respect to the rotation axis 9. In Figure 1, in a second cross-sectional plane represented by a side surface 23 formed by edges 19 and 21, the interface 7 extends in a convex curve and has an edge knot structure 25 with a recess 27. The blank 1 further has a holder 29 for fixing to a CAD / CAM device, as well as marks 31a and 31b that can be recognized by a CAD / CAM device, so that the trajectory of the interface 7 can be recognized by a CAD / CAM device.

[0035] [Figure 2] Figure 2 shows a schematic diagram of a further embodiment of the multicolor blank 1 in which the interface 7 between the first layer 3 and the second layer 5 in the cross-sectional plane 15 does not extend perfectly straight, but extends at least partially in an arc shape.

[0036] [Figure 3] Figure 3 shows a cross-section in the second cross-sectional plane 23, passing through the multicolor blank 1 shown in Figure 1. A generally convex curved trajectory can be seen at the interface 7 between the first layer 3 and the second layer 5. Edge knot structures 25, each having individual indentations 27, overlap this arc-shaped trajectory.

[0037] [Figure 4] Figure 4 shows a schematic diagram of a further embodiment of the blank 1 according to the present invention, in which the insertion shaft 8 extends perpendicular to the rotation axis of the holder 29. Furthermore, the position of the dental restoration 33 to be produced from the blank 1 is indicated on the blank 1, with a portion of the restoration 33, namely the portion intended to mimic the incisal edge of the anterior region of the restoration 33, located above the interface 7, and another portion of the restoration 33, namely the portion intended to primarily mimic the dentin layer, located below the interface 7. [Modes for carrying out the invention]

[0038] In further embodiments, the interface may be designed using color effects. This can prevent subsequent discoloration of dental restorations produced from the blank. The color effects can mimic, for example, enamel cracks, enamel plaques, or other features. Such color effects can be realized during the production of the blank, where the color effect is applied to the first layer before the second layer is applied to the first layer. 3D powder printing methods are also suitable for realizing color effects, where the effect is printed onto the blank and the blank is then sintered.

[0039] With respect to the blank material according to the present invention, the glass, glass ceramic, or ceramic is preferably selected from lithium silicate glass, lithium silicate glass ceramic, silicon dioxide glass, silicon dioxide glass ceramic, and / or zirconium oxide.

[0040] According to a first embodiment, the blank layer according to the present invention is preferably based on or composed of lithium silicate glass, lithium silicate glass with a core, or lithium metasilicate glass ceramic. Due to its relatively low strength, such a blank can be machined to give the shape of a desired dental restoration in a particularly simple manner. According to an alternative embodiment, the blank layer according to the present invention is based on lithium disilicate glass ceramic.

[0041] Particularly preferred are lithium silicate glass, lithium silicate glass with a core, lithium metasilicate glass ceramic or lithium disilicate glass ceramic, which consist of the following components: [Table 1] It contains at least one of the following, preferably all of them, in the indicated amounts, and the amounts of the components are calculated as oxides, as is common in the case of glass and glass ceramics.

[0042] Furthermore, lithium silicate glass, lithium silicate glass with a core, lithium metasilicate glass ceramic, or lithium disilicate glass ceramic preferably comprises the following components: [Table 2] It contains at least one of the following, in particular all of the indicated amounts: Here Me II O is a divalent oxide selected particularly from MgO, CaO, and / or SrO.

[0043] More preferred compositions of lithium silicate glass, lithium silicate glass with a core, lithium metasilicate glass ceramic, or lithium disilicate glass ceramic are described in EP 1 505 041 A1 and EP 1 688 398 A1.

[0044] In particular, a composition is preferred in which the amount of oxide of an element with atomic number 19 or greater in the first layer differs from the amount of oxide of an element with atomic number 19 or greater in the second layer by 2 wt.% or less, preferably 1.5 wt.% or less.

[0045] Surprisingly, it was found that the aforementioned preferred composition, and in particular the aforementioned preferred conditions regarding the amount of oxide with atomic number 19 or greater, makes it possible to provide first and second layers having nearly identical refractive indices despite their different colors. In this way, it is possible to provide blanks, and subsequently dentures, in which no dividing interface is visible between the layers.

[0046] Lithium silicate glass is typically produced by melting a suitable starting material. This glass can be converted to nucleated lithium silicate glass by heat treatment. The nuclei are suitable for the crystallization of lithium metasilicate and / or lithium disilicate. The nucleated lithium silicate glass can be converted to lithium metasilicate glass ceramic by heat treatment.

[0047] Finally, lithium metasilicate glass ceramics can be converted to high-strength lithium disilicate glass ceramics by further heat treatment. Therefore, lithium silicate glass, lithium silicate glass with a core, and lithium metasilicate glass ceramics are precursors to lithium disilicate glass ceramics.

[0048] A blank containing lithium metasilicate crystals as the main crystalline phase of the lithium metasilicate glass ceramic is more preferably a blank containing more than 5 vol.%, preferably more than 10 vol.%, and especially preferably more than 20 vol.% of lithium metasilicate crystals. The term "main crystalline phase" refers to the crystalline phase that has the highest volume proportion compared to other crystalline phases.

[0049] In further embodiments, a glass ceramic-based blank is preferred, containing a lithium silicate crystalline phase, particularly a lithium metasilicate or lithium disilicate crystalline phase, in addition to a further crystalline phase, preferably an SiO2 crystalline phase such as low-temperature quartz. Particularly preferred is such a blank having the following components: [Table 3] It contains at least one of the following, preferably all of them in the indicated amounts: Here Me I 2O is selected from the group consisting of K2O, Na2O, Rb2O, Cs2O and mixtures thereof, Me II O is selected from the group consisting of CaO, MgO, SrO, ZnO and mixtures thereof, Me III2O3 is selected from the group consisting of Al2O3, B2O3, Y2O3, La2O3, Ga2O3, In2O3, and mixtures thereof.

[0050] In the case of such glass ceramics, the molar ratio of SiO2 to Li2O is preferably in the range of 2.2 to 3.8. Furthermore, the lithium disilicate content in the glass ceramic is preferably more than 20 wt.%, preferably 25 to 55 wt.%. The low-temperature quartz content is also preferably 0.2 to 28 wt.%. A more preferable glass ceramic containing a low-temperature quartz crystal phase in addition to the lithium silicate crystal phase is described in EP 3 315 641.

[0051] In a preferred embodiment, the blank according to the present invention has a monolithic layer of lithium silicate glass, a monolithic layer of lithium silicate glass having a core, a monolithic layer of lithium metasilicate glass ceramic, or a monolithic layer of lithium disilicate glass ceramic.

[0052] The term "monolithic" refers to a continuous layer, and therefore distinct from discontinuous layers such as layers of particles, for example, layers of powder or granular material. The monolithic layers used in this invention may also be referred to as solid layers of glass and glass ceramics.

[0053] The presence of a monolithic layer in the blank according to the first aspect of the present invention also contributes to the fact that it can be converted into a desired high-strength dental restoration by heat treatment without substantial shrinkage. In contrast, discontinuous layers present in conventional blanks, such as pressed layers of powder or granular material, must be sintered to a higher density to produce the final dental restoration. However, this high-density sintering results in substantial shrinkage. Therefore, in order to produce a precisely fitting dental restoration, an enlarged form of the restoration must be produced first, and then this enlarged form is sintered to a higher density. However, such a procedure is complex and prone to failure. Furthermore, in each case, a precise determination of the initial enlargement ratio is required, which depends, among many, on precise sintering conditions and the type of blank used.

[0054] According to a second aspect, the blank layer according to the present invention is preferably based on or composed of silicon dioxide glass, silicon dioxide glass with a nucleus, or silicon dioxide glass ceramic. In particular, a blank in which the layer is based on or composed of silicon dioxide glass ceramic is preferred. Such a blank can be given the shape of a desired dental restoration relatively simply by machining, even in a fully crystallized form. In this case, post-machining heat treatment is no longer necessary, which is particularly advantageous for such a blank.

[0055] Particularly preferred are silicon dioxide glass, silicon dioxide glass with a core, or silicon dioxide glass ceramic, which comprises the following components: [Table 4] It contains at least one of the following, preferably all of them in the indicated amounts: Here Me I 2O is selected in particular from Na2O, K2O, Rb2O and / or Cs2O; Me II O is selected in particular from MgO, CaO, SrO and / or ZnO; Me III2O3 is selected particularly from Al2O3, B2O3, Y2O3, La2O3, Ga2O3 and / or In2O3; Me IV O2 is selected particularly from ZrO2, GeO2, CeO2, TiO2 and / or SnO2; Me V 2O5 is selected particularly from V2O5, Ta2O5 and / or Nb2O5; Me VI O3 is selected particularly from WO3 and / or MoO3.

[0056] Particularly preferably, the silicon dioxide glass ceramic contains SiO2, particularly low-temperature quartz, cristobalite or a mixture thereof, as the main crystal phase.

[0057] More preferably, the silicon dioxide glass, the silicon dioxide glass having a core, or the silicon dioxide glass ceramic is described in WO2015 / 173394A1.

[0058] The blank according to the second aspect preferably has a monolithic layer of silicon dioxide glass, a monolithic layer of silicon dioxide glass having a core, or a monolithic layer of silicon dioxide glass ceramic.

[0059] According to the third aspect, the first and second layers of the blank according to the present invention preferably contain un-sintered zirconium oxide or pre-sintered zirconium oxide.

[0060] Particularly preferably, the blank according to the third aspect contains at least one, preferably all, of the following components in the amounts indicated.

Table 5

[0061] The blanks according to the present invention, including blanks according to the first, second, and third embodiments of the present invention, preferably exist in the form of a block, a cube, a disc, or a cylinder having a cylindrical or elliptical base. In these forms, they can be further machined particularly concisely into a desired dental restoration. Particularly preferably, the blanks according to the present invention exist in the form of a block.

[0062] In a more preferred embodiment, the blank according to the present invention has a holder for fixing to a processing device. The holder allows the blank to be fixed to a processing device, in particular, such as a milling device or a grinding device. The holder is usually in the form of a nail, and the holder is preferably made of metal or plastic.

[0063] The present invention also relates to a method for producing blanks according to the present invention.

[0064] A method for producing a blank according to the present invention in a first aspect, i.e., a blank having a layer of lithium silicate glass, lithium silicate glass with a core, or lithium metasilicate glass ceramic, particularly a monolithic layer, or a blank according to the present invention in a second aspect, i.e., a blank having a layer of silicon dioxide glass, silicon dioxide glass with a core, or silicon dioxide glass ceramic, particularly a monolithic layer, (a1) To provide in a mold a first layer of lithium silicate glass, lithium silicate glass with a core, lithium metasilicate glass ceramic, silicon dioxide glass, silicon dioxide glass with a core, or silicon dioxide glass ceramic having a viscosity of at least 6.6 Pa·s, (b1) Forming the surface of the first layer to bring about the desired trajectory of the interface between the first and second layers of the blank, and (c1) Applying a second layer of lithium silicate glass, lithium silicate glass with a core, lithium metasilicate glass ceramic, silicon dioxide glass, silicon dioxide glass with a core, or silicon dioxide glass ceramic to the surface of the first layer. It is characterized by the following.

[0065] Particularly preferably, in step (a1), a first layer of glass, particularly lithium silicate glass or silicon dioxide glass, is provided in the mold.

[0066] The shaping of the surface of the first layer in step (b1) may preferably be achieved by pressing with a structured counter die, for example, a die made from graphite. Because the strength of the glass preferably used in steps (a1) and (b1) is relatively low, a small pressing force, for example less than 10 MPa, is sufficient to achieve the desired shaping.

[0067] Furthermore, in step (c1), it is preferable that the molded first layer is coated with a second layer of glass, particularly lithium silicate glass or silicon dioxide glass. This coating can be carried out, for example, by glass casting.

[0068] It is even more preferable that the blank is not subjected to any heat treatment for forming a crystalline phase between the formation of the interface and the coating with the material of the second layer. Rather, it is preferable that, following step (c1), the complete blank is subjected to a heat treatment for forming a crystalline phase, such as lithium metasilicate glass ceramic or silicon dioxide glass ceramic.

[0069] Alternatively, the blank according to the first or second embodiment may be produced by gradually filling a press die with starting material in powder form.

[0070] A third aspect of the present invention, namely a method for producing a blank having a layer of zirconium oxide, is: (a2) To provide a first layer of unsintered or dispersed zirconium oxide in the mold, (b) Forming the surface of the first layer to bring about the desired trajectory of the interface between the first and second layers of the blank, and (c2) Coating the surface of the first layer with a second layer of unsintered or dispersed zirconium oxide. It is characterized by the following.

[0071] The term "dispersed" refers to zirconium oxide homogeneously distributed in a suspension in a liquid medium, such as aqueous or organic solvent. The viscosity of the suspension is preferably high so that the molded shape of the surface is maintained after molding in step (b2).

[0072] Particularly preferable, following step (c2), the complete blank is subjected to heat treatment to provide a pre-sintered blank, thus improving machinability and precision in subsequent machining for the production of dental restorations.

[0073] Due to these properties, the blanks according to the present invention are particularly suitable for further processing into dental restorations.

[0074] Therefore, the present invention also relates to a method for producing dental restorations, (d1) A blank according to the first aspect of the present invention is given the shape of a dental restoration by machining, (e1) Perform at least one heat treatment to convert lithium silicate glass, lithium silicate glass with a core, or lithium metasilicate glass ceramic into lithium disilicate glass ceramic, (f1) If necessary, finish the surface of the resulting dental restoration. Alternatively, in an alternative embodiment, (d2) The blank according to the second aspect of the present invention is given the shape of a dental restoration by machining, (e2) Heat treatment as necessary to convert silicon dioxide glass or silicon dioxide glass with nuclei into silicon dioxide glass ceramic, or to increase the crystal content of silicon dioxide glass ceramic, (f2) If necessary, finish the surface of the resulting dental restoration. Alternatively, in an alternative embodiment, (d3) A blank according to a third aspect of the present invention is given the shape of a dental restoration by machining, (e3) Perform at least one heat treatment to convert unsintered or pre-sintered zirconium oxide into high-density sintered zirconium oxide, (f3) If necessary, finish the surface of the dental restoration. Regarding the method.

[0075] Dental restorations formed as desired can be easily milled from a blank according to the present invention by machining. According to a first aspect of the present invention, a blank having a layer of lithium silicate glass or lithium metasilicate glass ceramic with a core (step (d1)) is used, according to a second aspect, a blank having a layer of silicon dioxide glass ceramic (step (d2)) is used, or according to a third aspect of the present invention, a blank having a layer of pre-sintered zirconium oxide (step (d3)) is used.

[0076] Machining is typically carried out by material removal processes, particularly milling and / or grinding. Machining is preferably performed using computer-controlled milling and / or grinding devices. Particularly preferably, machining is performed during the CAD / CAM process.

[0077] In step (e1), the blank is subjected to heat treatment to bring about controlled crystallization of lithium disilicate, and thus the formation of lithium disilicate glass ceramic. The heat treatment is carried out at a temperature of 750 to 950°C, preferably 800 to 900°C. The heat treatment is carried out for a period of 1 to 30 minutes, preferably 2 to 15 minutes.

[0078] In step (e2), the blank is subjected to heat treatment as necessary. However, in the case of a silicon dioxide glass ceramic-based blank, it is preferable that the heat treatment in (e2) is omitted. Such a method is particularly simple and cost-effective, and therefore particularly preferred.

[0079] In step (e3), the blank is subjected to heat treatment to result in the formation of a high-density sintered zirconium oxide ceramic. The heat treatment is carried out at a temperature of 1050 to 1600°C, preferably 1450 to 1550°C. The heat treatment is carried out for a period of 0 to 240 minutes, preferably 5 to 180 minutes, and most preferably 30 to 120 minutes, the term “period” relating to the holding time at the maximum temperature.

[0080] Step (e1), (e2), or (e3) results in a dental restoration having layers of lithium disilicate ceramic, silicon dioxide ceramic, or zirconium oxide ceramic, which possess excellent mechanical properties and high chemical stability. Furthermore, due to the multiple layers of different colors, the dental restoration allows for excellent imitation of the optical properties of natural tooth material, such as the color gradient from dentin to the incisal edge. Finally, by utilizing steps (d1) to (f1) or (d2) to (f2), the restoration can also be produced from the blank according to the present invention without substantial shrinkage. This is particularly due to the fact that the blank according to the present invention, in the first and second embodiments, has a monolithic layer and does not have discontinuous layers such as powder or granular material layers, thereby eliminating sintering and associated shrinkage after molding. Therefore, by using the blank according to the present invention, dental restorations with precisely desired dimensions can be produced in a particularly simple manner. In the case of a blank according to the third aspect of the present invention, the problem of sintering shrinkage occurring in step (e3) can be solved in such a way that the first and second layers have substantially the same total shrinkage rate during step (e3). Such a setting of total shrinkage rate can be done so that the starting and final densities before and after heat treatment are the same in both layers in either case. In particular, with respect to the initiation of sintering, the individual layers can be matched to each other by their composition, in particular by the addition of sintering activators and / or inhibitors. Due to the oblique trajectory of the interface between the first and second layers, the fit of the dental restoration produced is determined by the fit of the first layer of the blank according to the present invention, which mimics the dentin layer and is less affected by the different sintering shrinkage behaviors that may occur in the individual layers than in the case of conventional blanks with a horizontal layer arrangement, and therefore by sintering shrinkage.

[0081] The dental restorations produced by the present invention are preferably selected from crowns, abutments, abutment crowns, inlays, onlays, veneers, facets, and bridges, as well as overstructures for the framework of multi-component restorations, which may consist of, for example, oxide ceramics, metals, or dental alloys.

[0082] In steps (f1), (f2), and (f3) as needed, the surface of the dental restoration may be further finished. In particular, it is possible to perform glaze firing at a temperature of 700–850°C or polish the restoration. In addition, a laminated material made from glass and / or glass ceramic may be applied.

[0083] Due to the specific properties of the blanks described in the present invention, the blanks are particularly suitable for producing dental restorations. Accordingly, the present invention also relates to the use of blanks for the production of dental restorations, particularly crowns, abutments, abutment crowns, inlays, onlays, veneers, facets and bridges, and superstructures. The use of blanks according to the present invention for the production of dentures in the anterior region, such as anterior crowns, is particularly preferred.

Claims

1. Independently of each other, Glass, Glass ceramic, or ceramic A dental blank comprising first and second layers based on wherein the blank is in the form of a block; and wherein the first layer and the second layer are different in color and form an interface, the interface extending obliquely to an axis of rotation, the axis of rotation being an axis about which the blank rotates during machining to form a desired dental restoration; wherein in a first cross-sectional plane through the blank, extending parallel to the insertion axis of the blank and parallel to the sides of the blank, the interface plane has an angle of 10 to 70° with respect to the axis of rotation, wherein the insertion axis is an axis extending in a cervical-incisal direction by passing through the centers of gravity of two opposing sides of the blank; and wherein the angle between the insertion axis and the rotation axis of the blank in the first cross-sectional plane is 70 to 110°; where: (i) the interface in the first cross-sectional plane extends substantially straight, and the interface in the first cross-sectional plane is at an angle of 20 to 80 degrees relative to the insertion axis; or (ii) the boundary surface in the first cross-sectional plane extends in an arc, and a best-fit line passing through the arc-shaped boundary surface in the first cross-sectional plane is at an angle of 20 to 80 degrees relative to the insertion axis; blank.

2. 2. The blank of claim 1, wherein in a first cross-sectional plane through the blank that extends parallel to the insertion axis of the blank, the interface has an angle of 10 to 60 degrees with respect to the axis of rotation.

3. 3. The blank of claim 1, wherein in a first cross-sectional plane through the blank that extends parallel to an insertion axis of the blank, the interface does not extend perpendicular to the insertion axis.

4. 4. The blank of claim 2 or 3, wherein the boundary surface in the first cross-sectional plane extends substantially straight, and the boundary surface in the first cross-sectional plane is at an angle of 30 to 80 degrees relative to the insertion axis.

5. 4. The blank of claim 2 or 3, wherein the boundary surface in the first cross-sectional plane extends in an arc, and a best fit line passing through the arc-shaped boundary surface in the first cross-sectional plane is at an angle of 30 to 80 degrees relative to the insertion axis.

6. 6. The blank according to claim 2, wherein the angle between the insertion axis and the rotation axis of the blank in the first cross-sectional plane is between 80 and 100 degrees.

7. 7. The blank of claim 2, wherein the interface surface extends in an arc through the blank in a second cross-sectional plane that extends perpendicular to the first cross-sectional plane.

8. The blank of claim 7 , wherein the interface at the second cross-sectional plane has an incisal knot structure.

9. 9. The blank of claim 8, wherein the incisal node structure comprises an indentation having a depth of 2 mm or less.

10. A blank according to any one of claims 1 to 9, wherein the first layer has a refractive index that differs from the refractive index of the second layer by no more than 0.

1.

11. A blank according to any one of the preceding claims, comprising markings that can be recognised by a CAD / CAM device and with which the position of the interface can be determined with an accuracy of 0.1 mm.

12. 12. The blank according to claim 1, wherein the glass, the glass ceramic or the ceramic is selected from lithium silicate glass, lithium silicate glass ceramic, silicon dioxide glass, silicon dioxide glass ceramic, and / or zirconium oxide.

13. The first and second layers, independently of one another, comprise: lithium silicate glass, a lithium silicate glass with a nucleus, or Lithium metasilicate glass ceramic Based on The lithium silicate glass, the lithium silicate glass with a core, or the lithium metasilicate glass ceramic comprises the following components: 【Table 6】 13. The blank of claim 12, comprising at least one or all of the following in the amounts indicated:

14. 14. The blank of claim 13, wherein the amount of oxides of elements having an atomic number of 19 or greater in the first layer differs from the amount of oxides of elements having an atomic number of 19 or greater in the second layer by no more than 2 wt.

15. The first and second layers, independently of one another, comprise: Silicon dioxide glass, a silicon dioxide glass with a nucleus, or Silicon dioxide glass ceramic Based on The silicon dioxide glass, the cored silicon dioxide glass, or the silicon dioxide glass ceramic comprises the following components: 【Table 7】 and containing at least one or all of the following in the amounts indicated: Here, Me Ｉ ２ O is Na ２ O.K. ２ O, Rb ２ O and / or Cs ２ O; ＩＩ O is selected from MgO, CaO, SrO and / or ZnO; Me ＩＩＩ ２ O ３ is Al ２ O ３ , B ２ O ３ , Y ２ O ３ , La ２ O ３ , Ga ２ O ３ and / or In ２ O ３ selected from: Me ＩＶ O ２ is ZrO ２ , GeO ２ , CeO ２ , TiO ２ and / or SnO ２ selected from: Me Ｖ ２ O ５ is V ２ O ５ , Ta ２ O ５ and / or Nb ２ O ５ selected from: Me ＶＩ O ３ Is WO ３ and / or MoO ３ 13. The blank of claim 12, wherein the blank is selected from:

16. 16. The blank of any one of claims 13 to 15, wherein the first and second layers are monolithic.

17. The first and second layers, independently of one another, comprise: Unsintered zirconium oxide, or Pre-sintered zirconium oxide 13. The blank of claim 12, comprising:

18. A blank according to any one of claims 1 to 17, comprising a holder for a processing device.

19. 19. A method for the production of a blank according to any one of claims 1 to 18, comprising the steps of: (a) providing a first layer based on glass, glass ceramic, or ceramic; (b) shaping a surface of the first layer to provide a desired trajectory of the interface between the first and second layers of the blank; (c) applying a second layer based on glass, glass ceramic or ceramic to the surface of the first layer; method.

20. 17. A method for producing a blank having a layer of lithium silicate glass, a lithium silicate glass with a nucleus, a lithium metasilicate glass ceramic, a silicon dioxide glass, a silicon dioxide glass with a nucleus, or a silicon dioxide glass ceramic according to any one of claims 13 to 16, comprising: (a1) providing a first layer of lithium silicate glass, cored lithium silicate glass, lithium metasilicate glass ceramic, silicon dioxide glass, cored silicon dioxide glass, or silicon dioxide glass ceramic in a mold, the first layer having a viscosity of at least 6.6 Pa s; (b1) shaping a surface of the first layer to provide a desired trajectory of the interface of the first and second layers of the blank; (c1) applying a second layer of lithium silicate glass, cored lithium silicate glass, lithium metasilicate glass ceramic, silicon dioxide glass, cored silicon dioxide glass or silicon dioxide glass ceramic to the surface of the first layer; method.

21. 18. A method for the production of a blank with a layer of zirconium oxide according to claim 17, comprising the steps of: (a2) providing a first layer of green or dispersed zirconium oxide in a mold; (b2) shaping a surface of the first layer to provide a desired trajectory of the interface of the first and second layers of the blank; (c2) coating a second layer of unsintered or dispersed zirconium oxide on the surface of the first layer; method.

22. 1. A method for the production of a dental restoration, comprising: (d) giving the blank according to any one of claims 1 to 18 the shape of the dental restoration by machining; (e) optionally, performing at least one heat treatment; (f) optionally finishing the surface of the resulting dental restoration; method.

23. (d1) giving the shape of the dental restoration to the blank according to any one of claims 13 to 14 and 16 by machining; (e1) carrying out at least one heat treatment to convert the lithium silicate glass, the lithium silicate glass containing nuclei, or the lithium metasilicate glass ceramic into a lithium disilicate glass ceramic, (f1) optionally finishing the surface of the resulting dental restoration; 23. The method of claim 22.

24. (d2) giving the shape of the dental restoration to a blank having a layer of zirconium oxide according to claim 17 by machining; (e2) carrying out at least one heat treatment to convert the green or pre-sintered zirconium oxide into densely sintered zirconium oxide; (f2) optionally finishing the surface of the resulting dental restoration; 23. The method of claim 22.

25. 25. The method according to any one of claims 22 to 24, wherein the machining is performed using a computer-controlled milling and / or grinding device.

26. 26. The method of any one of claims 22 to 25, wherein the dental restoration is selected from the group consisting of a crown, an abutment, an abutment crown, an inlay, an onlay, a veneer, a facet, a bridge, and a superstructure.

27. Use of a blank according to any one of claims 1 to 18 for the production of a dental restoration.

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