Method for producing a structured layer of a material for producing dental prostheses and device therefor - Patent application

Abstract

The present invention relates to a method for producing a synthetic resin object having a structured layer for producing a dental prosthesis, the method comprising the steps of: A) providing a first and a second PMMA-based compound that are uncured and have different colors; B) heating a first structured pressing surface to 90°C to 150°C; C) pressing the first PMMA-based compound with the heated first pressing surface, thereby resulting in a structured surface of the first PMMA-based compound; D) peeling off the first pressing surface; E) heating the first or second structured pressing surface to 90°C to 150°C; F) pressing the heated pressing surface with the first PMMA-based compound; The present invention also relates to an apparatus for carrying out the method, characterized in that: a) pressing a second PMMA-based compound with a pressing surface of the first PMMA-based compound, thereby resulting in a structured surface of the second PMMA-based compound; G) peeling off the pressing surface; H) overlapping the structured first and second PMMA-based compounds such that the structured surface of the second PMMA-based compound faces the structured surface of the first PMMA-based compound; and I) compressing the structured first PMMA-based compound together with the structured second PMMA-based compound to firmly bond the first and second PMMA-based compounds.

Description

[Technical field]

[0001] The present invention relates to a method for producing a structured layer of material for producing a dental prosthesis. The present invention further relates to an apparatus for carrying out said method.

[0002] The method is suitable for the permanent structuring of reactive mixtures, especially acrylate and methacrylate paste surfaces, and for the interlayer structured surfaces produced therefrom, which allows the production of natural-looking color transitions in the synthetic resin objects used for the production of dental prostheses, so that the dental prostheses have an appearance that is as natural as possible.

[0003] Dental prostheses are dentures (full or partial) or crowns and bridges that are intended to imitate or replace natural teeth.

[0004] The subtractive production of natural-looking dental prostheses made of composite resin or ceramic requires multiple material slices, the transitions between the individual layers being preferably not clearly defined and having a diffuse structure at the interfaces, in order to better correspond to the natural appearance of natural teeth.

[0005] US Patent No. 4,970,032 and US Patent No. 5,989,031 disclose multi-colored blanks for producing dental prostheses such as crowns. In this case, layers are arranged one on top of the other to give the dental prosthesis a natural appearance and to approximate natural teeth in terms of material stability and wear. Manufacturing methods include, for example, injection molding. However, this can result in undesirable, sharp, unnatural-looking interfaces.

[0006] From WO 2020 / 025795 and US 2020 / 0317561 A1, methods are known for producing ceramic blanks with color transitions, from which dental prostheses can be produced. The production of such ceramics and glass-ceramics, as well as their processing, is very costly. For this reason, production from synthetic resins is often preferred.

[0007] DE 10 2017 116 630 A1 discloses a method for producing a multi-layer sintered ceramic molded part with color transitions in order to produce color transitions that give a natural impression, where a separate partial densification of the green bodies of the ceramic slices to be joined together must be carried out before the green bodies of the ceramic slices to be joined together are joined.

[0008] From DE 102011055393, a multi-layer synthetic resin blank for the production of dental prostheses is known, in which liquid synthetic resin layers are applied to the profiled surface. These layers are then produced in a complex manner by a multi-component injection molding method. In this case, the synthetic resin layers are applied directly in liquid form. This method has the disadvantage that when the synthetic resin layers are applied, the structuring of the surface is lost or at least partially lost, since the structure begins to disappear or disappears due to the liquid synthetic resin layer. DE 102017122993 discloses a method for the production of a monochromatic polymerizable dental composite material, in which the parts of a multi-component mold for hot isostatic pressing can be heated. The method is aimed at preventing crack formation in monochromatic milling blocks. Color transitions and the composition of the milling blocks are not discussed, which would also interfere with the goal set in DE 102017122993, namely the production of milling blocks that are as uniform as possible.

[0009] From WO 2013 / 072287, a blank for an artificial tooth with a plurality of different color layers is known, in which two synthetic resin layers are filled into the cavity of an injection mold. By injecting a second synthetic resin layer into the same injection mold onto the not yet solidified first synthetic resin layer, the two synthetic resin layers are bonded to each other in such a way that a uniform color transition is promoted. A disadvantage in this regard is that the mixing nevertheless takes place along a uniform interface, whereby a dental prosthesis produced from such a blank has a straight linear structure that impairs the natural appearance of the denture. Furthermore, if highly crosslinked or viscous PMMA-based compounds are used, the miscibility of the synthetic resin is usually poor or almost nonexistent, so that in that case undesirable, unnatural-looking borders arise. Moreover, the described method is limited by its industrial implementation to thermoplastic processes only. This leads to significantly limited material properties in terms of functionality and resistance to polymerizable crosslinking reaction systems.

[0010] EP 3669818 A1 discloses a multicolor dental mill blank, which may be based on synthetic resin. The multicolor mill blank has several layers with rounded faces at the layer interfaces, called transition shapes. The layers can be joined to each other by overlapping, gluing or melting. The disadvantages of this are that the joining of the layers is laborious and, in the case of synthetic resins, the structure may be deformed when the second layer is poured in. In addition, it is necessary that the interfaces cannot form a predetermined breaking point, so that when joining synthetic resins, a prior crosslinking that is not complete is desirable, which has a negative effect on dimensional stability.

[0011] When unpolymerized slices are superimposed, more or less pronounced, sharp phase boundaries are produced, depending on the coloring of the individual layers. This affects the dental prosthesis subsequently produced from the polymerized synthetic resin object (blank) in the form of stripes. According to the prior art, a clearly defined shape can also be achieved by hardening the first layer before applying the second layer as a soft paste. This results in a clearly defined shape of the phase boundaries.

[0012] In principle, the following options exist for the production of multi-layer mouldings: 1. Slices of a paste-like material are superimposed and subsequently polymerized, which results in clearly defined phase boundaries of an unnatural appearance; 2. Direct production from the still liquid phase by superimposing the still pourable mixture (this is only possible for methyl methacrylate systems), which allows a diffusive transition and therefore a visually pleasing result, but the problem here is that all stages have to be produced just in time, as the liquid mixture is not storable, and the processing times are limited, making this process difficult to implement on a large scale; 3. As in EP 3 669 818 A, individual polymerized layers are produced on a structured surface and then combined with a paste that has not yet polymerized, but the resulting structures in this case have the disadvantage that the phase boundaries must exactly correspond to the geometric pattern of the pressed structures, only slightly structured rounded surfaces can be pressed, since otherwise a persistent adhesion of the polymerized material would occur, the transitions are clearly noticeable and the visibility depends on the quality of the coloring, and the process is multi-stage and therefore laborious; and 4. Made from a number of layers which have little contrast with one another. This method gives good results but is very laborious as several layers have to be made first and the layers have to be made very thin.

[0013] The object of the present invention is to overcome the disadvantages of the prior art. In particular, it is desirable to find the possibility of providing a method and a device for inexpensively and conveniently producing a synthetic resin object that has a natural appearance in relation to the natural color transitions of teeth, from which a dental prosthesis with a natural impression can be produced by milling or machining.

[0014] The problem according to the invention is solved by a method according to claim 1 and by a device according to claim 15. Preferred variants are claimed by the dependent claims 2-14 as well as 16 and 17.

[0015] The object of the present invention is therefore achieved by a method for producing a synthetic resin object with a structured layer for producing a dental prosthesis, the method comprising the steps of: A) providing a first PMMA based compound and a second PMMA based compound, the first PMMA based compound being uncured and having a first color, and the second PMMA based compound being uncured and having a second color, the second color of the second PMMA based compound being different from the first color of the first PMMA based compound; B) heating the first structured press surface to a temperature between 90°C and 150°C; C) pressing the first PMMA-based compound with a heated first structured pressing surface, thereby generating a structured surface of the first PMMA-based compound; D) then peeling the first press surface from the structured first PMMA-based compound, whereby the structured surface of the first PMMA-based compound remains intact; and E) heating the first structured press surface to a temperature between 90°C and 150°C or heating the second structured press surface to a temperature between 90°C and 150°C; F) Heated 1. pressing the second PMMA-based compound against the structured press surface or a heated second structured press surface, thereby producing a structured surface of the second PMMA-based compound; G) then peeling the first press surface or the second press surface from the structured second PMMA-based compound, whereby the structured surface of the second PMMA-based compound remains intact; H) then superposing the structured second PMMA-based compound onto the structured first PMMA-based compound such that the structured surface of the second PMMA-based compound faces the structured surface of the first PMMA-based compound; and I) Thereafter, the structured first PMMA-based compound is compressed together with the structured second PMMA-based compound to firmly bond the first PMMA-based compound and the second PMMA-based compound. It is characterized by:

[0016] By PMMA-based compounds is understood a not completely crosslinked, fluid and moldable synthetic resin composed of polymethyl methacrylate (PMMA). PMMA-based compounds consist of 50-90% by weight of powdered polymer, for example PMMA, advantageously 60-70% by weight of PMMA, in particular PMMA bead polymer, and 10-50% by weight of monomers, advantageously 30-40% by weight of monomers, in particular (meth)acrylates, (meth)acrylate derivatives and / or crosslinkers, for example di- and polyfunctional (meth)acrylates.

[0017] The PMMA-based compound is advantageously rated at 10 kN / m 2 It is desirable that the material be plastically deformable under the above pressure.

[0018] A structured surface is understood within the meaning of the present invention to be a surface having macroscopic structures, whereby structures of preferably 1 mm to 3 mm can be provided.

[0019] In order for the synthetic resin object to be suitable for the production of dental prostheses, it must be made of a biocompatible material. Furthermore, it is desirable for the synthetic resin object to have a sufficient hardness after hardening for use in the chewing area of ​​the jaw. For this purpose, it is possible to provide that the fully hardened synthetic resin object has a Vickers hardness of at least 100HV10 according to DIN EN ISO 6507-1:2018 to DIN EN ISO 6507-4:2018.

[0020] Preferably, the PMMA-based compound used in the present invention is a highly crosslinked PMMA-based compound.As a result, it is possible to achieve high strength of the synthetic resin object and thus of the dental prosthesis made from the synthetic resin object.Therefore, this dental prosthesis is also suitable for replacing the occlusal surface.

[0021] The sequence of steps B) to D) and the sequence of steps E) to G) can be carried out simultaneously or in parallel.

[0022] A step J) of curing the structured first PMMA-based compound and the co-compressed second PMMA-based compound can be provided, which step J) advantageously takes place after step I).

[0023] The synthetic resin object is then ready for further processing into a dental prosthesis.

[0024] Furthermore, the uncured third PMMA-based compound is pressed with two heated structured press surfaces arranged opposite each other, thereby generating structured surfaces on both sides of the third PMMA-based compound, wherein the third PMMA-based compound has a third color different from the first color of the first PMMA-based compound and the second color of the second PMMA-based compound, and then the press surfaces are peeled off from the third PMMA-based compound structured on both sides, wherein the two structured surfaces of the third PMMA-based compound are kept intact; in step H), In this case, the structured third PMMA-based compound is disposed between the structured second PMMA-based compound and the structured first PMMA-based compound such that their structured surfaces are in contact with each other. In step I), the structured first PMMA-based compound is then compressed together with the structured second PMMA-based compound and the structured third PMMA-based compound disposed therebetween to firmly bond the first PMMA-based compound, the second PMMA-based compound and the third PMMA-based compound.

[0025] This results in natural looking multi-step transitions in synthetic resin objects, which can be easily produced by the present method.

[0026] Also, in step H), a plurality of further PMMA-based compounds are arranged together between the structured first PMMA-based compound and the structured second PMMA-based compound, and the colors of the adjacent PMMA-based compounds, the first PMMA-based compound, the second PMMA-based compound and the plurality of PMMA-based compounds, are preferably different from each other; and before step H), each of the plurality of further PMMA-based compounds is structured with two heated structured press surfaces arranged opposite each other, thereby forming structured surfaces on both sides of the plurality of further PMMA-based compounds. and then peeling the pressing surface away from the two double-sided structured further PMMA-based compounds, while the two structured surfaces of the further PMMA-based compounds are kept intact; and in step I), it is then possible to provide for compressing the structured first PMMA-based compound together with the structured second PMMA-based compound and the structured further PMMA-based compounds arranged therebetween, to firmly bond the first PMMA-based compound with the second PMMA-based compound and the further PMMA-based compounds arranged therebetween.

[0027] A separate press surface may be used for each structured surface of every PMMA-based compound, or a limited number of press surfaces may be used repeatedly, consecutively or sequentially. Preferably, different press surfaces are always used for adjacent PMMA-based compounds or layers produced therefrom. It is sufficient that the first and second press surfaces are always used alternately.

[0028] This results in natural looking multi-step transitions in synthetic resin objects, which can be easily produced by the present method.

[0029] Preferably, it is possible to provide that the plurality of further PMMA-based compounds is between 2 and 20 further PMMA-based compounds, particularly preferably between 2 and 10 further PMMA-based compounds.

[0030] The pressing of the first PMMA-based compound in step C) with the heated first structured pressing surface and the pressing of the second PMMA-based compound in step F) with the first structured pressing surface or the heated second structured pressing surface are carried out at a pressure of 10 kN / m 2 ~500kN / m 2 Pressure of 10 kN / m 2 ~100kN / m 2 , particularly preferably 10 kN / m 2 ~50kN / m 2 It is also possible to provide for the pressure to be

[0031] This makes it possible to ensure that the first and second fluid PMMA-based compounds are moldable with a consistency suitable for processing and that their surfaces can be structured as desired, so that the desired transition occurs easily.

[0032] Further pressing of a third or further PMMA-based compound with two heated structured pressing surfaces arranged opposite each other was performed at a pressure of 10 kN / m 2 ~500kN / m 2 Pressure of 10 kN / m 2 ~100kN / m 2 , particularly preferably 10 kN / m 2 ~50kN / m 2 It is possible to provide for the pressure to be

[0033] This makes it possible to ensure that each of the applied fluid PMMA-based compounds is moldable with a consistency suitable for processing and that their surfaces can be structured as desired, so that the desired transitions occur easily.

[0034] According to a preferred development, it is possible to provide that the pressing of the first PMMA-based compound in step C) with the heated first structured pressing surface and the pressing of the second PMMA-based compound in step G) with the heated first structured pressing surface or with the heated second structured pressing surface is carried out for a period of 1 s to 50 s, preferably 5 s to 30 s, wherein advantageously and if present, the pressing of the third PMMA-based compound or a number of further PMMA-based compounds with two heated structured pressing surfaces arranged opposite each other is carried out for a period of 1 s to 50 s, preferably 5 s to 30 s.

[0035] This makes it possible to ensure that the surface structuring of the PMMA-based compounds formed by each pressing surface is retained even after bonding of the PMMA-based compounds together, thus resulting in a natural-looking transition between the layers of PMMA-based compounds.

[0036] It is also possible to provide that the first structured pressing surface and / or the second structured pressing surface are heated during pressing, advantageously providing that all structured pressing surfaces used are heated during pressing.

[0037] Therefore, advantageously, and if used, the two structured pressing surfaces facing each other are also heated during pressing.

[0038] This makes it possible to prevent cooling of the structured pressing surface during shaping of the surface of the respectively processed PMMA-based compound.

[0039] It can further be provided that the first structured pressing surface and / or the second structured pressing surface, advantageously all structured pressing surfaces used, have structures with a profile height of 1 mm to 5 mm, preferably a profile height of 2 mm to 3 mm.

[0040] Thus, advantageously, and also when used, two structured pressing surfaces facing each other have structures with a profile height of 1 mm to 5 mm, preferably 2 mm to 3 mm.

[0041] Structures with this profile height allow for blurring of the interface, resulting in a color transition that is particularly natural looking with respect to tooth color transitions.

[0042] Furthermore, for compression in step I), 10 kN / m 2 ~500kN / m 2 , preferably 10 kN / m 2 ~50kN / m 2 It is possible to provide for the application of a pressure of

[0043] This achieves a strong bond between the PMMA-based layers and allows the gas inclusions to be forced out of the material.

[0044] It can furthermore be provided that the first structured pressing surface and / or the second structured pressing surface, advantageously all structured pressing surfaces used, have a honeycomb structure or have a plurality of peaks protruding from the pressing surface or have a plurality of pyramidal or conical ridges protruding from the pressing surface, preferably the protruding peaks or the protruding pyramidal or conical ridges being arranged periodically on the pressing surface.

[0045] Thus, advantageously, and if used, two structured pressing surfaces facing each other have a plurality of peaks projecting from the pressing surfaces or a plurality of pyramidal or conical protuberances projecting from the pressing surfaces.

[0046] This allows the first structured press surface or the structured press surface to be manufactured easily and cheaply, and the color transition produced from the PMMA-based compound is uniformly diffused across the interface and therefore natural.

[0047] It is also possible for the first structured pressing surface and / or the second structured pressing surface, advantageously all structured pressing surfaces used, to consist of silicone or be coated with silicone or to consist of metal, in particular stainless steel, preferably the metal being coated, particularly preferably coated with Teflon or silicone.

[0048] Advantageously, and if used, the two structured pressing surfaces facing each other therefore consist of silicone or of metal, optionally with a coating.

[0049] These materials can be molded well onto the structured press surface: metals have high thermal conductivity, and silicones have low adhesion to fluid PMMA-based compounds.

[0050] It is further possible to provide that the PMMA-based compound has a viscosity of 1 Pa·s to 1000 Pa·s at the time of use and at a temperature of 20°C.

[0051] Here, the viscosity can be measured by a viscometer according to EN ISO 3219.

[0052] This viscosity provides adequate dimensional stability for the structured surface of PMMA-based compounds, which prevents the surface structure from being lost when the pressed surface is peeled off, resulting in a uniform interface for the color transition.

[0053] The problem underlying the present invention is also solved by a method for producing a dental prosthesis, which method includes the method described above and further comprises the steps of: K) machining one or more individual dental prostheses from the fully cured synthetic resin object according to method steps A) to I) and optionally J), wherein a tooth axis of the one or more individual dental prostheses extends from the base end of the dental prostheses, the dental prostheses being subtractively machined from the synthetic resin object such that the tooth axis passes through several layers of the PMMA-based compound of the synthetic resin object, preferably wherein the machining is performed by a subtractive CAM process.

[0054] This further perfects the method and results in a natural looking dental prosthesis.

[0055] The problem underlying the present invention is also solved by an apparatus for carrying out the method, which comprises at least one structured pressing surface and a bottom plate, where at least one structured pressing surface is heatable and / or at least two structured pressing surfaces arranged opposite each other and which are heatable, at least two containers with at least two fluid PMMA-based compounds pigmented in different colors or at least two containers with starting components for producing at least two fluid PMMA-based compounds pigmented in different colors, and a press for compressing together at least two structured PMMA-based compounds stacked one on top of the other.

[0056] The device is directly suitable for the production of structured PMMA-based compounds for producing layered synthetic resin objects as blanks for cutting out dental prostheses.

[0057] The different colors of the PMMA-based fluid compounds can be achieved by different colorants (such as various color pigments), but also by different concentrations of the same colorant. The starting components for producing at least two PMMA-based fluid compounds colored in different colors can be, for example, cement powder and monomer liquid for producing a PMMA-based fluid cement, and at least one liquid or powder colorant for coloring the PMMA-based fluid cement. In that case, the PMMA-based compounds are produced by mixing the cement powder with one of the monomer liquids and colorants, where the colorant can be added in different concentrations or different colorants can be added to color each PMMA-based compound in a different color.

[0058] Here, it can be provided that the device comprises a peripheral boundary wall arranged on the bottom plate, within which at least one structured pressing surface is movable, or that the peripheral boundary wall is arranged around at least two structured pressing surfaces arranged opposite each other.

[0059] This makes it possible to prevent the PMMA-based compound from leaking out uncontrollably in the lateral direction and achieve a compact design of the device.

[0060] It can further be provided that the apparatus further comprises at least one filling unit for applying the fluid PMMA-based compound onto the bottom plate or between two structured pressing surfaces arranged opposite each other, advantageously the at least one filling unit being suitable and provided for filling the PMMA-based compound within the peripheral boundary (if present).

[0061] This allows for a standardized filling of the equipment with the fluid PMMA-based compound and therefore ensures a consistent quality of the layered synthetic resin objects.

[0062] The invention is based on the surprising finding that by using a heated structured pressing surface it is possible to generate at least temporarily durable structures in a fluid PMMA-based compound, which structures, when combined with further structured PMMA-based compounds, cause diffuse and therefore natural-looking transitions of different colors of the PMMA-based compounds. By compressing such pre-structured PMMA-based compounds, the sufficiently stable surface structures fit together and do not completely disappear and revert to their original state, so that the natural-looking boundary elongation is maintained in the synthetic resin object thus generated.

[0063] The method according to the invention allows the pasty surface to be permanently pre-structured without the material of the PMMA-based compound sticking to the structured press surface. In contrast to other methods, this also allows for the first time a stronger structuring of the PMMA-based compound and an expansion of the phase boundary region. These are special features of the products produced by this method.

[0064] Depending on the characteristics and implementation of the texture, very diffuse phase boundaries can be produced, but if necessary it is also possible to produce clearly defined transitions. The method according to the invention causes a slight solidification of the treated surface, which further has a positive effect on possible segregation events at the phase boundaries.

[0065] In the present patent application it has been found that structuring a pasty surface of a methacrylate such as PMMA by pressing with a conventional mechanical tool, for example a structured metal surface, is not possible due to the high tack of the material.

[0066] Furthermore, the viscoelastic behavior of PMMA-based compounds leads to a significant reset effect, so that the structures created on the surface disappear or at least become significantly weaker.

[0067] By means of step H), the second structured PMMA-based compound is superimposed on the first structured PMMA-based compound, or a third or further PMMA-based compound is inserted so that the structured surfaces of adjacent PMMA-based compounds are aligned with each other, the blurring of adjacent PMMA-based compounds can be arbitrarily influenced by a predetermined alignment of the surfaces. The precise positioning of each PMMA-based compound with respect to each other is usually a random product, which is desirable for a natural appearance. The structure can range from extensive flattening to direct blurring while retaining the cast shape.

[0068] According to the invention, for example and preferably, pressing surfaces with well-defined and sharp structures, such as pyramidal apexes with a height of 2 mm to 3 mm, as well as mechanical sanding, are used during production. By heating the structured pressing surface to a temperature of 90° C. to 150° C., preferably 100° C. to 140° C. before pressing, dimensional stability of the freshly structured surface can be achieved. Preferably, the pressing of the pasty material onto the surface is performed with a force of 10 to 500 kN / m 2 This is done for about 5 to 30 seconds at the specified pressure.

[0069] Exemplary embodiments of the present invention are described below with reference to nine schematic diagrams and one flow chart, which are not intended to be limiting of the present invention. [Brief description of the drawings]

[0070] [Figure 1] FIG. 2 shows a sequence of the method according to the invention using the device according to the invention as five schematic, superimposed partial cross-sectional views of the device according to the invention for carrying out the method according to the invention. [Diagram 2] FIG. 2 is a schematic perspective view of a second heatable structured pressing plate for carrying out the method according to the invention. [Diagram 3] FIG. 3 is a schematic detail view of the surface of a PMMA-based compound molded with the second structured press plate according to FIG. 2. [Figure 4]FIG. 2 is a schematic detail view as a cross-sectional enlargement of the structured surface of a third heatable structured pressing plate for carrying out the method according to the invention. [Diagram 5] FIG. 5 is a schematic cross-sectional view of the structure of the third structured pressing plate according to FIG. 4. [Figure 6] FIG. 2 is a schematic partial perspective view of a fourth heatable structured press plate for carrying out the method according to the invention. [Figure 7] 1 is a schematic top view of a structured surface of a PMMA-based compound molded using a heated structured press plate according to a method according to the present invention. FIG. [Figure 8] FIG. 2 is an enlarged cross-section of the interface of two PMMA-based compounds of different colors bonded together in a relatively short press by the method according to the invention. [Figure 9] FIG. 2 is an enlarged cross-section of a further interface of two PMMA-based compounds with different colors that are bonded together in a relatively long press by the method according to the invention. [Figure 10] 2 shows a sequence of the method according to the invention for producing a synthetic resin object with a structured layer for producing a dental prosthesis as a flow chart.

[0071] FIG. 1 shows a sequence of the method according to the invention using the device according to the invention as five schematic, superimposed, partial cross-sectional views of the device according to the invention for carrying out the method according to the invention.

[0072] The device can comprise a base plate 1 and a boundary wall 2, which can be placed on the base plate 1 as a ring in the manner of a springform or can be fixed to the base plate 1. The device can further comprise a dosing unit 3. The dosing unit 3 comprises a tube 4 and a container 5. By means of the dosing unit 3, a defined amount of a first PMMA-based compound 6 in fluid form can be applied to the base plate 1. For this purpose, the dosing unit 3 can be configured, for example, as a dosing device in the manner of a soap dispenser in order to dispense a defined amount of the first PMMA-based compound 6. This situation is shown in the upper diagram of FIG. 1. The first PMMA-based compound 6 in fluid form has a first color, for example a light tooth color.

[0073] The upper side of the first PMMA-based compound 6 facing the bottom plate 1 can be structured by means of a stamper 7 with a preheated structured pressing surface 8. For this purpose, the pressing surface 8 can form the surface of the stamper 7. The pressing surface 8 can have a temperature of 100° C. to 140° C. when pressing the first PMMA-based compound 6, which temperature can advantageously be adapted to the material of the first PMMA-based compound 6. To heat the structured pressing surface 8, an electric resistance heater (not shown) can be arranged in the stamper 7. The temperature of the structured pressing surface 8 is advantageously adjustable. It can also be provided that the temperature of the structured pressing surface 8 is measured and / or controlled by a temperature sensor (not shown).

[0074] The heated pressing surface 8 is pressed against the still fluid first PMMA-based compound 6 for a few seconds, thereby generating a structured surface 10 on the first PMMA-based compound 6. This situation is shown in the second diagram from the top in FIG. 1. The stamper 7 with the structured pressing surface 8 is then peeled off from the structured surface 10 of the first PMMA-based compound 6. Here, the solidification of the first PMMA-based compound 6 is achieved by the heat transferred by the stamper 7, so that the structure of the structured surface 10 of the first PMMA-based compound 6 remains intact. This situation is shown in the third diagram from the top in FIG. 1.

[0075] The device may further comprise a second filling unit (not shown). Similar to the first PMMA-based compound 6, the fluid second PMMA-based compound 12 may be structured by the device with the base plate 1, the boundary wall 2 and a stamper 7 having a heated structured pressing surface 8 on one side. The fluid second PMMA-based compound 12 has a second color different from the color of the first PMMA-based compound 6, for example a dark tooth color. The structured second PMMA-based compound 12 may then be placed on the structured surface 10 of the structured first PMMA-based compound 6 with its surface 14 thus structured. This situation is shown in the fourth view from the top of FIG. 1. Instead of using a stamper 7 with a pressing surface 8, a second stamper (not shown) with a different shape of the pressing surface may also be used, whereby the second PMMA-based compound 12 has a different surface structure from the first PMMA-based compound 6.

[0076] Optionally, at least one third PMMA-based compound (not shown) structured on two opposite faces can be inserted between the structured first PMMA-based compound 6 and the structured second PMMA-based compound 12. The structuring of the two mutually opposite structured faces of the third PMMA-based compound can be carried out by means of two heated pressing surfaces arranged opposite each other. For this purpose, for example, the bottom part 1 can be replaced by a further stamper (not shown) with a pressing surface configured similarly to the stamper 7 with the pressing surface 8, such as for example the stamper 27 according to FIG. 2.

[0077] The structured first PMMA-based compound 6 and the structured second PMMA-based compound 12, and optionally at least one structured third PMMA-based compound arranged therebetween, can then be joined to one another by pressing. For this purpose, a press 16 can be used, which presses the PMMA-based compounds 6, 12 against one another and against the bottom plate 1. This situation is shown in the bottom diagram according to Fig. 1. For this purpose, a force of 1 to 10 tonnes can be applied.

[0078] After hardening, a synthetic resin object is thus produced, consisting of two hardened PMMA-based compounds 6, 12, which are bonded to one another via the structured surfaces 10, 14. This synthetic resin object is removed from the apparatus and from it a dental prosthesis with a natural appearance can be produced by subtractive methods.

[0079] In this way, multi-layered synthetic resin objects can be produced with interlocking PMMA-based compounds. The structuring results in natural-looking interfaces between the PMMA-based compounds in the synthetic resin, as shown in Figures 8 and 9.

[0080] FIG. 2 shows a schematic perspective view of a second heatable structured pressing plate for carrying out the method according to the invention, and FIG. 3 shows a schematic detailed view of the surface of a PMMA-based compound 37 molded with the second structured pressing plate according to FIG. 2. The structured pressing plate is a stamper 27. The stamper 27 can have a flat cylindrical shape. One side of the stamper 27 is designed as a heatable structured pressing surface 28, by means of which the PMMA-based compound 37 can be molded. For this purpose, a plurality of four-sided pyramidal apexes 29 can be arranged from the structured pressing surface 28. The pyramidal apexes 29 are arranged on the structured pressing surface 28 as a periodic lattice. The stamper 27 can be made of metal, for example stainless steel. Furthermore, an electric resistance heater (not shown) can be arranged inside the stamper 27 or on its external side facing the structured pressing surface 28, by means of which the structured pressing surface 28 can be heated. The tip of pyramidal apex 29 protrudes from the base by 2 mm to 3 mm.

[0081] The stamper 27 may be integrated into a heating device so as to allow thermostatically controlled heating of the press plate. With this setup, a PMMA-based compound 37 can be structured. The PMMA-based compound 37 then has a structured surface 38 molded as a negative of the structured press surface 28. The structured surface 38 thus has a number of periodically juxtaposed pyramidal depressions 39. A number of such structured PMMA-based compounds 37 with different colors can be placed on top of each other with their structured surfaces 38 and then pressed together.

[0082] Figure 4 shows a schematic detail as a cross-sectional enlargement of the structured surface 48 of a third heatable structured pressing plate 47 for carrying out the method according to the invention, and Figure 5 shows a schematic cross-sectional view of the structure of the third structured pressing plate 47 in this respect. The pressing plate 47 has a honeycomb-like structuring in the form of honeycomb-shaped (hexagonal) depressions 49 tapering towards the bottom. As a result, the PMMA-based compound structured thereby has the negative of the structured surface 48 shown in Figures 4 and 5. The depth of the honeycomb-shaped depressions is 2 mm to 3 mm.

[0083] FIG. 6 shows a schematic partial perspective view of a fourth heatable structured pressing plate 57 for carrying out the method according to the invention. The structured pressing plate 57 is configured like a stamper. One side of the structured pressing plate 57 can be designed as a circular heatable structured pressing surface 58, by means of which PMMA-based compounds can be molded. For this purpose, a plurality of four-sided pyramidal depressions 59 can be arranged from the structured pressing surface 58. The pyramidal depressions 59 are arranged on the structured pressing surface 58 as a periodic square lattice. The pyramidal depressions have a depth of 2 mm to 3 mm. The structured pressing plate 57 can have a protruding edge 60 that surrounds the structured pressing surface 58 at its edge. The structured pressing plate 57 can consist of a temperature-stable synthetic resin, for example silicone. Additionally, an electric resistance heater (not shown) may be located inside the structured press plate 57 or on the outside of the structured press plate 57 facing the structured press surface 58, and the electric resistance heater may heat the structured press surface 58. A silicone structured press plate 57 is easy and inexpensive to manufacture. However, silicone as a material does not have the same fatigue strength and therefore the same manufacturability as most metals, especially steel. Therefore, according to the present invention, it is preferred to construct the structured press surface from a metal, especially steel.

[0084] 7 shows a schematic top view of a structured surface 68 of a PMMA-based compound 67 molded using a heated structured press plate according to the method of the present invention. From the structured surface 68 rises a number of pyramidal depressions 69 periodically arranged in a square lattice. Depression 69 is a tip that is 2mm to 3mm from the bottom. Backwards A number of such structured PMMA-based compounds 67 having different colors can be placed on top of each other with structured surface 68 and then compressed together.

[0085] Figure 8 shows an enlarged cross-section of an interface of two PMMA-based compounds with different colours bonded together in a relatively short press by the method according to the invention, and Figure 9 shows an enlarged cross-section of a further interface of two PMMA-based compounds with different colours bonded together in a relatively long press by the method according to the invention. The images were taken with a LEICA DMS 1000 microscope at 4-6x magnification.

[0086] To produce the layered composite, a standard dental material (Flexecure Dentin dental material, Kulzer GmbH) as a first PMMA-based compound was heated at a temperature of 115° C. with a flow rate of 450 cm 2 The pressing was performed with a pressure of about 100 kg of pressing force over a period of 20 to 70 seconds, using a structured pressing surface 38, as partially shown in FIG.

[0087] After pressing, the structured PMMA-based compound was bonded, compressed and polymerized.

[0088] In the following, an exemplary method is described on the basis of the device according to the invention as described in Fig. 1. The exemplary method sequence is illustrated in the flow chart according to Fig. 10. However, the description can easily be transferred to other exemplary embodiments.

[0089] In operation 100, a first PMMA-based compound 6 in fluid form having a first color can be provided. In parallel with this, in operation 101, a second PMMA-based compound 12 in fluid form having a second color can be provided, and optionally, in operation 102, at least one third PMMA-based compound in fluid form having a third color can be provided.

[0090] In operation 103, which follows operation 100, a first PMMA-based compound 6 in fluid form can be applied to a surface, such as for example the surface of the soleplate 1. Similarly, in operation 104, which follows operation 101, a second PMMA-based compound 12 in fluid form can be applied to a surface, such as for example the surface of the soleplate 1. Similarly, in operation 105, which follows optional operation 102, at least one third PMMA-based compound in fluid form can be introduced between the two heated structured pressing surfaces.

[0091] Work step 103 can be followed in work step 106 by structuring of the surface 10 of the first PMMA-based compound 6 by means of a heated pressing surface 8. Similarly, work step 104 can be followed in work step 107 by structuring of the surface 14 of the second PMMA-based compound 12 by means of the heated pressing surface 8 or another pressing surface, and optionally work step 105 can be followed in work step 108 by structuring of two opposite surfaces of at least one third PMMA-based compound by means of two heated structured pressing surfaces.

[0092] Thereafter, in operation 109 following operation 106, press surface 8 can be peeled off from first PMMA based compound 6. Similarly, in operation 110 following operation 107, press surface 8 or another press surface can be peeled off from second PMMA based compound 12. In any flow of the method, optional operation 108 can be followed in optional operation 111 by peeling off two press surfaces from at least one third PMMA based compound.

[0093] After these working steps, now, in working step 112, the structured second PMMA-based compound 12 can be placed on the structured first PMMA-based compound 6 such that the two structured surfaces 10, 14 of the structured first PMMA-based compound 6 and the structured second PMMA-based compound 12 are aligned with each other. Alternatively, at least one structured third PMMA-based compound can also be placed between the structured first PMMA-based compound 6 and the structured second PMMA-based compound 12 such that the two structured surfaces 10, 14 of the structured first PMMA-based compound 6 and the structured second PMMA-based compound 12 are aligned with each other.

[0094] Then, in operation step 113, all the PMMA based compounds 6, 12 arranged in a stack are compressed together and the PMMA based compounds 6, 12 are cured.

[0095] In operation 114, the resulting hardened layered synthetic resin body can be removed.

[0096] Then, in optional step 115, at least one dental prosthesis may be milled from the hardened layered synthetic resin body using a subtractive process, such as, for example, a CAM mill.

[0097] The features of the invention disclosed in the foregoing description, in the claims, the drawings and the exemplary embodiments may be essential for the realization of the invention in its various embodiments, both individually and in any combination thereof. [Explanation of symbols]

[0098] 1 Bottom plate 2 Boundary wall 3 Filling Unit 4 tubes 5 containers 6 PMMA compounds 7. Stamper 8 Structured Press Surface 9. Stamper 10 Structured surface 12 Second PMMA compound 14 Structured Surface 16 Press Machine 27 Stamper 28 Structured Press Surface 29 Pyramid-shaped apex 37 Structured PMMA-based compounds 38 Structured Surface 39 Pyramid-shaped depression 47 Press plate 48 Structured Press Surface 49 Honeycomb-like depressions 57 Press plate 58 Structured Press Surface 59 Pyramid-shaped depression 60 Edge 67 Structured PMMA-based compounds 68 Structured Surface 69 Pyramid-shaped depression 70 First PMMA Compound 72 Second PMMA Compound 74 Interface 80 First PMMA Compound 82 Second PMMA Compound 84 Interface 100 Operation Step: Providing a first PMMA-based compound in a fluid state having a first color 101 Operation step: Providing a second PMMA-based compound in a fluid state having a second color 102 Optional operation step: Providing at least one fluid third PMMA-based compound having a third color. 103 Operation Step: Application of a fluid first PMMA-based compound to the surface 104 Operation Step: Application of a fluid second PMMA-based compound to the surface 105 Optional working step: introduction of at least one fluid third PMMA-based compound between the two heated structured press surfaces. 106 Working step: Structuring the surface of the first PMMA-based compound using a heated press surface 107 Working step: Structuring the surface of the second PMMA-based compound using a heated press surface 108 Optional working step: structuring of two opposing surfaces of at least one third PMMA-based compound using two heated structured press surfaces. 109 Work process: Peeling of the press surface from the first PMMA compound 110 Operation: Peeling of the press surface from the second PMMA-based compound 111 Optional work step: Peeling off the two press surfaces from at least one third PMMA-based compound. 112 Work step: placing a structured second PMMA-based compound on the structured first PMMA-based compound so that the two structured surfaces of the structured first and second PMMA-based compounds are aligned with each other, or placing at least one structured third PMMA-based compound between the structured first PMMA-based compound and the structured second PMMA-based compound so that the two structured surfaces of the structured first and second PMMA-based compounds are aligned with each other. 113 Working process: Compression of all the PMMA-based compounds placed in layers together and hardening of the PMMA-based compounds 114 Work process: Removal of hardened layered synthetic resin object 115 Optional work step: Production of at least one dental prosthesis from a hardened layered synthetic resin object

Claims

1. 1. A method for producing a synthetic resin object having a structured layer for producing a dental prosthesis, said method comprising the steps of: A) providing a first PMMA based compound and a second PMMA based compound, the first PMMA based compound being uncured and having a first color, the second PMMA based compound being uncured and having a second color, the second color of the second PMMA based compound being different from the first color of the first PMMA based compound; B) heating the first structured press surface to a temperature of from 90°C to 150°C; C) pressing the first PMMA-based compound with a heated first structured pressing surface, thereby generating a structured surface of the first PMMA-based compound; D) thereafter, peeling the first press surface from the structured first PMMA-based compound, wherein the structured surface of the first PMMA-based compound remains intact; and E) heating the first structured pressing surface to a temperature of from 90° C. to 150° C. or heating the second structured pressing surface to a temperature of from 90° C. to 150° C.; F) pressing the second PMMA-based compound with a heated first structured pressing surface or a heated second structured pressing surface, thereby generating a structured surface of the second PMMA-based compound; G) thereafter, peeling the first press surface or the second press surface from the structured second PMMA-based compound, wherein the structured surface of the second PMMA-based compound remains intact; H) then superposing a structured second PMMA-based compound onto the structured first PMMA-based compound such that the structured surface of the second PMMA-based compound faces the structured surface of the first PMMA-based compound; and I) thereafter, compressing the structured first PMMA-based compound together with the structured second PMMA-based compound to form a strong bond between the first PMMA-based compound and the second PMMA-based compound; A method comprising:

2. J) curing the structured first PMMA-based compound and the co-compressed second PMMA-based compound.

2. The method according to claim 1, characterized in that step J) is carried out after step I).

3. pressing an uncured third PMMA-based compound with two heated structured press surfaces arranged opposite each other, thereby generating structured surfaces on both sides of the third PMMA-based compound, wherein the third PMMA-based compound has a third color different from the first color of the first PMMA-based compound and the second color of the second PMMA-based compound, and then peeling the press surfaces away from the third PMMA-based compound structured on both sides, while the two structured surfaces of the third PMMA-based compound are kept intact; and in step H), 3. The method according to claim 1 or 2, wherein the structured third PMMA-based compound is disposed between the structured second PMMA-based compound and the structured first PMMA-based compound such that the structured surfaces are in contact with each other, and in step I), the structured first PMMA-based compound is then compressed together with the structured second PMMA-based compound and the structured third PMMA-based compound disposed therebetween to firmly bond the first PMMA-based compound, the second PMMA-based compound and the third PMMA-based compound.

4. In step H), a plurality of further PMMA-based compounds are arranged together between the structured first PMMA-based compound and the structured second PMMA-based compound, wherein the colors of the adjacent PMMA-based compounds, the first PMMA-based compound, the second PMMA-based compound and the plurality of PMMA-based compounds, are different from each other, and before step H), each of the plurality of further PMMA-based compounds is structured with two heated structured press surfaces arranged opposite each other, whereby structured surfaces are generated on both sides of the plurality of further PMMA-based compounds, and then 3. The method according to claim 1 or 2, characterized in that the pressing surface is peeled off from the two double-sided structured further PMMA-based compounds, while the two structured surfaces of the further PMMA-based compounds are kept intact, and in step I), the structured first PMMA-based compound is then compressed together with the structured second PMMA-based compound and the structured further PMMA-based compounds arranged therebetween, to firmly bond the first PMMA-based compound with the second PMMA-based compound and the further PMMA-based compounds arranged therebetween.

5. The pressing of the first PMMA-based compound in step C) with the heated first structured pressing surface and the pressing of the second PMMA-based compound in step F) with the first structured pressing surface or the heated second structured pressing surface are carried out at a pressure of 10 kN / m ２ ~500kN / m ２ 5. The process according to claim 1, wherein the process is carried out at a pressure of 0.1 to 1000.

6. The third or further PMMA-based compound is pressed with two heated structured press surfaces arranged opposite each other at a pressure of 10 kN / m. ２ ~500kN / m ２ 5. The process according to claim 3 or 4, wherein the process is carried out at a pressure of

7. 7. The method according to claim 1, wherein the pressing of the first PMMA-based compound in step C) with the heated first structured pressing surface and the pressing of the second PMMA-based compound in step G) with the heated first structured pressing surface or with the heated second structured pressing surface is carried out for a period of 1 s to 50 s, with the pressing of a third PMMA-based compound or a number of further PMMA-based compounds, if present, with two heated structured pressing surfaces arranged opposite each other being carried out for a period of 1 s to 50 s.

8. 8. The method according to claim 1, wherein the first structured pressing surface and / or the second structured pressing surface are heated during pressing.

9. 9. The method according to claim 1, wherein the first structured pressing surface and / or the second structured pressing surface has structures with a profile height of 1 mm to 5 mm.

10. For the compression in step I), 10 kN / m ２ The method according to any one of claims 1 to 9, wherein a pressure of up to 500 kN / m 2 is applied.

11. 11. The method according to claim 1, wherein the first structured pressing surface and / or the second structured pressing surface has a honeycomb structure or has a plurality of peaks protruding from the pressing surface or has a plurality of pyramidal or conical ridges protruding from the pressing surface, the protruding peaks or the protruding pyramidal or conical ridges being periodically arranged on the pressing surface.

12. 12. The method according to claim 1, wherein the first structured pressing surface and / or the second structured pressing surface is made of silicone or is coated with silicone or is made of metal, the metal being coated.

13. 13. The method according to claim 1, wherein the PMMA-based compound has a viscosity of from 1 Pa·s to 1000 Pa·s at the time of use and at a temperature of 20°C.

14. A method for producing a dental prosthesis, comprising the steps of: K) machining one or more individual dental prostheses from the synthetic resin object fully cured by the method steps A) to I) and, if present, J), wherein the tooth axis of the one or more individual dental prostheses extends from the base end of the dental prostheses, and wherein the dental prostheses are subtractively machined from the synthetic resin object such that the tooth axis passes through the layers of the PMMA-based compound of the synthetic resin object. A method comprising:

15. 15. An apparatus for carrying out the method according to any one of claims 1 to 14, said apparatus comprising: at least one structured pressing surface (8, 28, 48, 58) and a bottom plate (1), wherein said at least one structured pressing surface (8, 28, 48, 58) is heatable and / or at least two structured pressing surfaces (8, 28, 48, 58) arranged opposite each other and which are heatable, At least two containers (5) containing at least two fluid PMMA-based compounds (6, 12, 37, 67, 70, 72, 80, 82) pigmented in different colors or at least two containers (5) containing starting components for producing at least two fluid PMMA-based compounds (6, 12, 37, 67, 70, 72, 80, 82) pigmented in different colors, and A press (16) for compressing together at least two structured PMMA-based compounds (6, 12, 37, 67, 70, 72, 80, 82) stacked one on top of the other. An apparatus comprising:

16. 16. The device according to claim 15, further comprising a peripheral boundary wall (2) arranged on the bottom plate (1), within which the at least one structured pressing surface (8, 28, 48, 58) is movable or which is arranged around the at least two structured pressing surfaces (8, 28, 48, 58) arranged opposite each other.

17. 17. Apparatus according to claim 15 or 16, characterized in that the apparatus further comprises at least one filling unit (3) for applying the fluid PMMA-based compound (6, 12, 37, 67, 70, 72, 80, 82) onto the base plate (1) or between the two structured pressing surfaces (8, 28, 48, 58) arranged opposite each other, the at least one filling unit (3) being suitable and provided for filling the PMMA-based compound (6, 12, 37, 67, 70, 72, 80, 82) into the peripheral boundary (2).

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