METHOD FOR PRODUCEING STRUCTURED LAYERS FOR MATERIALS FOR DENTURE MANUFACTURING AND DEVICE FOR THIS PURPOSE

Description

[0001] The invention relates to a method for producing structured layers in materials for dental prosthesis production. The invention further relates to a device for implementing such a method.

[0002] The process is suitable for the permanent structuring of pasty surfaces of reactive mixtures, particularly acrylates and methacrylates, and for the resulting structured surfaces between the layers. This allows natural-looking color transitions to be created in a plastic body used for the manufacture of dentures, giving the dentures the most natural appearance possible.

[0003] A dental prosthesis refers to prosthetic teeth for artificial dentures (full or partial dentures) as well as crowns and bridges that are intended to replicate or replace a natural tooth.

[0004] To produce natural-looking dentures made of plastic or ceramic using subtractive manufacturing processes, multilayered material discs are required. The transitions between the individual layers should not be sharply defined, but rather exhibit a diffuse structure at the interfaces to better match the natural appearance of natural teeth.

[0005] US 4970032 A and US 5989031 A disclose multicolored blanks for the production of dental prostheses, such as crowns. The layers are arranged one above the other to give the dental prosthesis a natural appearance and to approximate the stability and wear of the material to that of a natural tooth. Injection molding, for example, is mentioned as a manufacturing process. However, this can result in undesirable and unnatural-looking sharp interfaces. US 2016 / 0220337 A1 discloses a blank for the production of dental prostheses in which a core region with a different color is provided in a bed of a first material.

[0006] WO 2020 / 025795 A1 and US 2020 / 0317561 A1 disclose methods for producing a ceramic blank with color transitions, from which dental prostheses can be fabricated. The production of such ceramics and glass ceramics is very complex, as is their processing. Therefore, production from plastic is often preferred.

[0007] DE 10 2017 116 630 A1 discloses a method for producing a multi-layered, sintered ceramic white body with color transitions for creating natural-looking color transitions. In this method, separate partial densification of the green bodies of the ceramic discs to be joined together must take place before the green bodies are bonded. DE 10 2011 055 393 B4 discloses a multi-layered plastic blank for the production of dental prostheses, in which a liquid plastic layer is applied to a profiled surface. The layers are produced there using a complex multi-component injection molding process. The plastic layers are applied directly in liquid form. This process has the disadvantage that the surface structuring is lost, or at least partially lost, during the application of the plastic layer because the liquid plastic layer dissolves or dissolves the structures.DE 10 2017 122 993 B4 discloses a method for producing a monochrome polymerizable dental composite material, in which parts of a multi-part casting mold can be heated for hot isostatic pressing. The method is intended to prevent cracking in the monochrome milling blocks. Color transitions or the assembly of milling blocks are not addressed and would also be detrimental to the objective of DE 10 2017 122 993 B4, namely the production of milling blocks that are as homogeneous as possible.

[0008] WO 2013 / 072287 A1 discloses a blank for artificial teeth with several different color layers, in which two plastic layers are filled into cavities of an injection mold. By injecting the second plastic layer onto the not yet solidified first plastic layer into the same injection mold, the two plastic layers are intended to bond with each other in such a way that a homogeneous color transition is promoted. The disadvantage of this is that the mixing still takes place along a flat interface, meaning that dental prostheses made from such a blank will have a straight line structure that is detrimental to the natural appearance of the denture teeth. In addition, the miscibility of the plastics is usually poor or almost impossible when highly cross-linked or adhesive PMMA-based materials are used, resulting in undesirable, unnatural-looking parting lines.Furthermore, due to its technical implementation, the described process is limited exclusively to thermoplastic processes. This leads to significantly limited material properties in terms of function and resistance to polymerizable, crosslinking reactive systems.

[0009] EP 3 669 818 A1 discloses a dental multi-color milling blank that can be based on plastic. The multi-color milling blank has several layers with rounded surfaces in an interface between the layers known as the transition geometry. The layers can be joined by superimposing, gluing, or melting. The disadvantage of this is that joining the layers is complex, and with plastics, there is a risk that the structures will deform when the second layer is poured on. Furthermore, the interface should be prevented from forming a predetermined breaking point, so that incomplete prior crosslinking would be better when joining plastics, although this negatively impacts dimensional stability.

[0010] When unpolymerized disc-shaped bodies are stacked on top of each other, a more or less pronounced, sharp phase boundary results, depending on the coloring of the individual layers. This results in a striped pattern in the dental work subsequently fabricated from the polymerized plastic body (blank). According to the state of the art, a clearly defined geometry can also be achieved by curing a first layer before applying the second layer as a soft paste. This clearly defines the phase boundary.

[0011] In principle, the following options exist for the production of multi-layer molded bodies: 1. Layering pasty material discs and subsequent polymerization, which leads to sharply defined phase boundaries with an unnatural appearance; 2. Production directly from the still-liquid phase by layering still-pourable mixtures (this is only possible with methyl methacrylate systems), which leads to diffuse transitions and thus to a visually satisfactory result. However, the problem here is that the liquid mixtures cannot be stored, thus necessitating just-in-time production at all stages, and the processing time is also limited, making the process difficult to implement on a large scale; 3.Production of polymerised individual layers on a structured surface and subsequent combination with still unpolymerised paste analogous to EP 3 669 818 A1, whereby a structure is created which has the disadvantages that the phase boundary corresponds exactly to the geometric pattern of the pressed structure, that only slightly structured and rounded surfaces can be pressed, as otherwise retentive adhesion of the polymerised material occurs, that the transitions are sharply pronounced and visibility depends on the quality of the colouring and that the process is multi-stage and therefore more complex; and 4. Production from many layers with only very low contrast to one another, whereby this process leads to good results, but the effort is very high due to the large number of layers that have to be produced beforehand and the layers have to be made very thin.

[0012] The object of the invention is to overcome the disadvantages of the prior art. In particular, a method and device are to be found that can be used to produce a plastic body in a cost-effective and uncomplicated manner that has a natural appearance with regard to natural tooth color transitions, whereby natural-looking dentures can be milled or machined from the plastic body.

[0013] The objects of the invention are achieved by a method according to claim 1 and a device according to claim 15. Preferred variants are claimed in subclaims 2 to 14 and 16 and 17.

[0014] The objects of the invention are thus achieved by a method for producing a plastic body with structured layers for the production of dental prostheses, the method being characterized by the following steps: A) Providing a first PMMA-based mass and a second PMMA-based mass, wherein the first PMMA-based mass is uncured and has a first color, and wherein the second PMMA-based mass is uncured and has a second color, wherein the second color of the second PMMA-based mass differs from the first color of the first PMMA-based mass; B) Heating a first structured pressing surface to a temperature between 90°C and 150°C; C) Pressing the first PMMA-based mass with the heated first structured pressing surface, thereby creating a structured surface of the first PMMA-based mass; D) Subsequently detaching the first pressing surface from the structured first PMMA-based mass, wherein the structured surface of the first PMMA-based mass is retained;and E) heating the first structured pressing surface to a temperature between 90°C and 150°C or heating a second structured pressing surface to a temperature between 90°C and 150°C; F) pressing the second PMMA-based mass with the first heated structured pressing surface or the second heated structured pressing surface, thereby creating a structured surface of the second PMMA-based mass; G) subsequently detaching the first pressing surface or the second pressing surface from the structured second PMMA-based mass, wherein the structured surface of the second PMMA-based mass is retained; H) subsequently placing the structured second PMMA-based mass on top of the structured first PMMA-based mass such that the structured surface of the second PMMA-based mass is aligned in the direction of the structured surface of the first PMMA-based mass;and I) subsequently pressing the first structured PMMA-based mass with the second structured PMMA-based mass so that a firm bond is formed between the first PMMA-based mass and the second PMMA-based mass. ;

[0015] A PMMA-based composition is a not fully crosslinked, fluid, and moldable plastic made of polymethyl methacrylate (PMMA). The PMMA-based composition consists of 50 to 90 wt.% powdered polymers, such as PMMA, preferably 60 to 70 wt.% PMMA, in particular PMMA bead polymers, and 10 to 50 wt.% monomers, preferably 30 to 40 wt.% monomers, wherein the monomers particularly include (meth)acrylates, derivatives of (meth)acrylates, and / or crosslinkers, such as di- and polyfunctional (meth)acrylates.

[0016] The PMMA-based mass should preferably be plastically deformable at a pressure of 10 kN / m 2 or more.

[0017] For the purposes of the present invention, a structured surface is understood to mean a surface with a macroscopic structure. Structures between 1 mm and 3 mm in size can preferably be provided.

[0018] To be suitable for the production of dentures, the plastic body must be made of a biocompatible material. Furthermore, after curing, the plastic body should have sufficient hardness for use in the chewing area of ​​a jaw. For this purpose, the fully cured plastic body can have a Vickers hardness of at least 100 HV10 according to DIN EN ISO 6507-1:2018 to -4:2018.

[0019] The PMMA-based materials used in the present invention are preferably highly cross-linked PMMA-based materials. This allows for high strength of the plastic body and thus of the dentures made from the plastic body. The dentures are therefore also well suited for replacing chewing surfaces.

[0020] The sequence of steps B) to D) and the sequence of steps E) to G) can also be carried out simultaneously or in parallel.

[0021] It can be provided that a step J) curing of the structured first PMMA-based mass and the second PMMA-based mass pressed therewith, wherein step J) preferably takes place after step I).

[0022] This makes the plastic body ready for further processing into dentures.

[0023] Furthermore, it can be provided that a pressing of an uncured third PMMA-based mass takes place with two heated structured pressing surfaces arranged opposite one another, thereby creating a structured surface on both sides of the third PMMA-based mass, wherein the third PMMA-based mass has a third coloration that differs from the first coloration of the first PMMA-based mass and from the second coloration of the second PMMA-based mass, subsequent detachment of the pressing surfaces from the third PMMA-based mass structured on both sides, wherein the two structured surfaces of the third PMMA-based mass are retained, wherein in step H), the structured third PMMA-based mass is arranged between the structured second PMMA-based mass and the structured first PMMA-based mass, so that the structured surfaces abut one another,and wherein in step I) the subsequent pressing of the first structured PMMA-based mass with the second structured PMMA-based mass and with the third structured PMMA-based mass arranged therebetween takes place, so that a firm connection is made between the first PMMA-based mass, the second PMMA-based mass and the third PMMA-based mass.

[0024] This creates a multi-stage, natural-looking transition in the plastic body, which can be easily produced using the process.

[0025] Alternatively, it can be provided that in step H) a total of several further PMMA-based masses are arranged between the first structured PMMA-based mass and the structured second PMMA-based mass, wherein preferably the colorations of adjacent PMMA-based masses of the first, the second and the plurality of PMMA-based masses differ from one another, wherein before step H) each of the plurality of further PMMA-based masses is structured with two heated structured pressing surfaces arranged opposite one another, thereby creating a structured surface on both sides of the plurality of further PMMA-based masses, and thereafter the pressing surfaces are detached from the plurality of further PMMA-based masses structured on both sides, wherein the two structured surfaces of the plurality of further PMMA-based masses are retained,in step I), the subsequent pressing of the first structured PMMA-based mass with the second structured PMMA-based mass and with the several further structured PMMA-based masses arranged therebetween takes place, so that a firm connection is created between the first PMMA-based mass, the second PMMA-based mass and the several further structured PMMA-based masses arranged therebetween.

[0026] A separate pressing surface can be used for each of the structured surfaces of all PMMA-based materials, or a limited number of pressing surfaces can be used repeatedly, continuously, or permuted. It is preferable to always use different pressing surfaces for adjacent PMMA-based materials or layers produced from them. For this purpose, it is sufficient to always alternate between the first pressing surface and the second pressing surface.

[0027] This creates a multi-stage, natural-looking transition in the plastic body, which can be easily produced using the process.

[0028] Preferably, it can be provided that the plurality of further PMMA-based masses are between two and twenty further PMMA-based masses, particularly preferably between two and ten further PMMA-based masses.

[0029] It can also be provided that the pressing of the first PMMA-based mass in step C) with the heated first structured pressing surface and the pressing of the second PMMA-based mass in step F) with the first structured pressing surface or with the heated structured second pressing surface takes place with a pressure between 10 kN / m 2< and 500 kN / m 2<, preferably with a pressure between 10 kN / m 2< and 100 kN / m 2<, particularly preferably with a pressure between 10 kN / m 2< and 50 kN / m 2<.

[0030] This ensures that the fluid first PMMA-based mass and the fluid second PMMA-based mass are moldable at a consistency suitable for processing and that their surfaces can be structured in the desired manner, so that the desired transitions are created in a simple manner.

[0031] Furthermore, it can be provided that the pressing of the third PMMA-based mass or the further PMMA-based masses with the two heated structured pressing surfaces arranged opposite one another takes place with a pressure between 10 kN / m 2< and 500 kN / m 2<, preferably with a pressure between 10 kN / m 2< and 100 kN / m 2<, particularly preferably with a pressure between 10 kN / m 2< and 50 kN / m 2<.

[0032] This ensures that each of the fluid PMMA-based masses used can be molded at a consistency suitable for processing and that their surfaces can be structured in the desired manner, so that the desired transitions are created easily.

[0033] According to a preferred development, it can be provided that the pressing of the first PMMA-based mass in step C) with the heated first structured pressing surface and the pressing of the second PMMA-based mass in step G) with the heated first structured pressing surface or with the heated second structured pressing surface takes place for a period of time between 1 s and 50 s, preferably for a period of time between 5 s and 30 s, wherein preferably and if present the pressing of the third PMMA-based mass or the several further PMMA-based masses with the two heated structured pressing surfaces arranged opposite one another takes place for a period of time between 1 s and 50 s, preferably for a period of time between 5 s and 30 s.

[0034] This ensures that the surface structuring of the PMMA-based masses formed with the respective pressing surface(s) is retained even after the PMMA-based masses have been bonded together, thus creating a natural-looking transition between the layers of the PMMA-based mass.

[0035] It can also be provided that the first structured pressing surface and / or the second structured pressing surface is or are heated during pressing, preferably all structured pressing surfaces used are heated during pressing.

[0036] Preferably and if applied, the two opposing structured pressing surfaces are also heated during pressing.

[0037] This can prevent cooling of the structured pressing surface(s) during the forming of the surface of the PMMA-based mass being processed.

[0038] Furthermore, it can be provided that the first structured pressing surface and / or the second structured pressing surface, preferably all structured pressing surfaces used, have structures with a profile height between 1 mm and 5 mm, preferably with a profile height between 2 mm and 3 mm.

[0039] Preferably and if applied, the two opposing structured pressing surfaces also have structures with a profile height between 1 mm and 5 mm, preferably with a profile height between 2 mm and 3 mm.

[0040] Structures with this profile height allow the interface to be blurred, which results in a particularly natural-looking transition in the coloration with regard to color transitions in teeth.

[0041] Furthermore, it can be provided that for pressing in step I) a pressure between 10 kN / m 2< to 500 kN / m 2< is applied, preferably between 10 kN / m 2< to 50 kN / m 2< is applied.

[0042] This ensures that the PMMA-based layers are firmly joined together and gas inclusions can be pressed out of the material.

[0043] Preferably, it can further be provided that the first structured pressing surface and / or the second structured pressing surface, preferably all structured pressing surfaces used, have a honeycomb structure or a plurality of peaks protruding from the pressing surface or have a plurality of pyramid-shaped or conical elevations protruding from the pressing surface, wherein preferably the protruding peaks or the protruding pyramid-shaped or conical elevations are arranged periodically in the pressing surface.

[0044] Preferably, and if applied, the two opposing structured pressing surfaces also have a plurality of peaks protruding from the pressing surface or a plurality of pyramid-shaped or conical elevations protruding from the pressing surface.

[0045] This allows the first structured pressing surface or the structured pressing surfaces to be manufactured in a simple and cost-effective manner and the color transitions produced from the PMMA-based masses are uniformly diffused and thus natural across the entire interface.

[0046] It can also be provided that the first structured pressing surface and / or the second structured pressing surface, preferably all structured pressing surfaces used, consist of silicone or are coated with silicone or consist of a metal, in particular of a stainless steel, wherein preferably the metal is coated, particularly preferably coated with Teflon or silicone.

[0047] Preferably, and where used, the two opposing structured pressing surfaces are also made of silicone or metal, optionally with a coating.

[0048] These materials are easy to form into structured press surfaces. Metals have high thermal conductivity, and silicone has poor adhesion to the fluid PMMA-based materials.

[0049] Furthermore, it can be provided that the PMMA-based masses have a viscosity between 1 Pa s and 1000 Pa s at the time of their application and at a temperature of 20 °C.

[0050] The viscosity can be determined using a viscometer according to EN ISO 3219.

[0051] This viscosity ensures suitable dimensional stability for the structured surfaces of the PMMA-based materials. This prevents the surface structure from dissolving when the pressing surfaces are removed, thus preventing the color transition from becoming a flat interface.

[0052] The objects underlying the present invention are also achieved by a method for producing dental prostheses, wherein the method comprises a method as described above and the method is additionally characterized by the following step: K) machining one dental prosthesis or several individual dental prostheses out of the fully cured plastic body according to method steps A) to I) and optionally J), wherein a tooth axis of the dental prosthesis or tooth axes of the several individual dental prostheses runs or run from a basal end of the dental prosthesis or the dental prostheses, wherein the dental prosthesis or the dental prostheses are subtractively machined out of the plastic body in such a way that the tooth axis or the tooth axes run or run through several layers of the PMMA-based masses of the plastic body and wherein the machining is preferably carried out with the aid of a subtractive CAM method.

[0053] This further completes the procedure and results in dentures with a natural appearance.

[0054] The objects underlying the present invention are also achieved by a device for implementing such a method, the device comprising at least one structured pressing surface and a base plate, wherein the at least one structured pressing surface is heatable, and / or at least two structured pressing surfaces arranged opposite one another which are heatable, at least two containers containing at least two differently colored fluid PMMA-based masses or at least two containers containing the starting components for producing at least two differently colored fluid PMMA-based masses, and a press for pressing at least two structured PMMA-based masses stacked on top of one another together.

[0055] The device is directly suitable for producing the structured PMMA-based masses for the production of a layered plastic body as a blank for milling out dental prostheses.

[0056] The different colors of the fluid PMMA-based masses can be achieved by using different colorants (such as different color pigments) or by using different concentrations of the same colorant. The starting components for producing the at least two differently colored fluid PMMA-based masses can be, for example, a cement powder and a monomer liquid for producing a fluid PMMA cement, and at least one liquid or powder colorant for coloring the fluid PMMA cement. The PMMA-based masses are then produced by mixing the cement powder with the monomer liquid and one of the colorants. The colorant can be added in different concentrations for differently colored PMMA-based masses, or different colorants can be added.

[0057] It can be provided that the device has a circumferential boundary wall which is arranged on the base plate and in which the at least one structured pressing surface is movable or which is arranged around the at least two structured pressing surfaces arranged opposite one another.

[0058] This prevents the PMMA-based masses from leaking out laterally in an uncontrolled manner and allows a compact design of the device to be achieved.

[0059] Furthermore, it can be provided that the device additionally has at least one filling device for applying the fluid PMMA-based masses to the base plate or between the two structured pressing surfaces arranged opposite one another, wherein preferably the at least one filling device is suitable and provided for filling the PMMA-based masses within the circumferential boundary (if present).

[0060] This allows a standardized filling of the device with fluid PMMA-based masses, thus ensuring a consistent quality of the layered plastic body.

[0061] The invention is based on the surprising discovery that heated, structured pressing surfaces make it possible to create at least temporarily durable structures in fluid PMMA-based masses. When combined with another structured PMMA-based mass, these structures create a diffuse and thus natural-looking transition between different colorations of the PMMA-based masses. By pressing such pre-structured PMMA-based masses, the sufficiently stable surface structures are pushed into one another and do not completely dissolve again, thus maintaining a natural-looking boundary line in the resulting plastic body.

[0062] The processes according to the invention allow for the permanent pre-structuring of pasty surfaces without adhesion of PMMA-based material to the structured pressing surfaces. Unlike other processes, this also enables, for the first time, a more pronounced structuring and an enlargement of the phase boundary zone in PMMA-based materials. These are the particular characteristics of the products manufactured using this process.

[0063] Depending on the texture and the application, very diffuse phase boundaries can be created, but sharply defined transitions can also be achieved if necessary. The process according to the invention ensures a slight hardening of the treated surfaces, which also has a positive effect on potential demixing processes at the phase boundaries.

[0064] It was found in the present patent application that structuring the pasty surfaces of methacrylates such as PMMA using normal mechanical tools, for example by pressing with structured metal surfaces, is not possible due to the high stickiness of the materials.

[0065] The viscoelastic behavior of PMMA-based materials also leads to a significant recovery effect, so that the surface structure created disappears or is at least significantly weakened.

[0066] By placing the structured second PMMA-based mass on top of the structured first PMMA-based mass or by inserting the third PMMA-based mass or the further PMMA-based masses so that the structured surfaces of adjacent PMMA-based masses are aligned with each other, as per step H), the encoding of adjacent PMMA-based masses can optionally be influenced by a defined alignment of the surfaces to each other. The exact positioning of the PMMA-based masses relative to each other is usually a random product—which is desirable due to the natural appearance. The structure can be achieved by extensive flattening or even direct encoding while preserving the impression geometries.

[0067] According to the invention, pressing surfaces with a distinct, even sharp-edged structure are used during production, such as, for example, and preferably, pyramid-shaped points with a height of 2 mm to 3 mm, similar to mechanical files. By heating the structured pressing surfaces to temperatures between 90°C and 150°C, preferably between 100 and 140°C, before pressing, dimensional stability of the freshly structured surfaces can be achieved. Preferably, the pasty materials are pressed onto the surfaces for approximately 5 s to 30 s under a defined pressure of between 10 and 500 kN / m².

[0068] In the following, exemplary embodiments of the invention are explained with reference to nine schematically illustrated figures and a flowchart, without, however, limiting the invention. In the following: Figure 1: the sequence of a method according to the invention with a device according to the invention as five superimposed schematic partial sectional views of the device according to the invention for implementing a method according to the invention, Figure 2 : a schematic perspective view of a second heatable structured press plate for implementing a method according to the invention, Figure 3 : a schematic detailed view of a press plate structured with the second Figure 2 shaped surface of a PMMA-based mass, Figure 4 : a schematic detailed view as a detail enlargement of the structured surface of a third heatable structured press plate for implementing a method according to the invention, Figure 5 : a schematic cross-sectional view of the structure of the third structured press plate according to Figure 4 , Figure 6: a schematic perspective partial view of a fourth heatable structured press plate for implementing a method according to the invention, Figure 7 : a schematic plan view of a structured surface of a PMMA-based mass formed with a heated structured press plate according to a method according to the invention, Figure 8 : an enlargement of a cross-section of an interface between two PMMA-based masses bonded together by a method according to the invention with different colors during short pressing, Figure 9 : an enlargement of a cross-section of another interface between two PMMA-based masses bonded together by means of a method according to the invention, with different coloration after prolonged pressing, and Figure 10 : the sequence of a method according to the invention for producing a plastic body with structured layers for the production of dental prostheses as a flow diagram.

[0069] Figure 1 shows the sequence of a method according to the invention with a device according to the invention as five schematic partial cross-sectional views of the device according to the invention for implementing a method according to the invention arranged one above the other.

[0070] The device can have a base plate 1 and a boundary wall 2, wherein the boundary wall 2 can rest on the base plate 1 as a ring in the manner of a springform pan or can be fastened to the base plate 1. The device can further have a filling device 3. The filling device 3 can have a pipe 4 and a container 5. A fluid first PMMA-based mass 6 can be applied to the base plate 1 in a defined amount using the filling device 3. The filling device 3 can for this purpose be constructed, 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 mass 6. This situation is shown in the top illustration of the Figure 1 shown. The fluid first PMMA-based mass 6 has a first color, for example, a light tooth color.

[0071] The upper surface of the first PMMA-based mass 6 opposite the base plate 1 can be structured using a stamp 7 with a previously heated structured pressing surface 8. For this purpose, the pressing surface 8 can form a surface of the stamp 7. The pressing surface 8 can have a temperature between 100°C and 140°C during pressing of the first PMMA-based mass 6, wherein the temperature can preferably be adapted to the material of the first PMMA-based mass 6. To heat the structured pressing surface 8, an electrical resistance heater (not shown) can be arranged in the stamp 7. The temperature of the structured pressing surface 8 can preferably be adjusted. It can also be provided that the temperature of the structured pressing surface 8 is measured and / or regulated using a temperature sensor (not shown).

[0072] The heated pressing surface 8 is pressed onto the still fluid first PMMA-based mass 6 for several seconds, thereby creating a structured surface 10 on the first PMMA-based mass 6. This situation is shown in the second figure from the top of the Figure 1 shown. Subsequently, the stamp 7 with the structured pressing surface 8 is released from the structured surface 10 of the first PMMA-based mass 6. The structure of the structured surface 10 of the first PMMA-based mass 6 is retained, since the heat transferred from the stamp 7 solidifies the first PMMA-based mass 6. This situation is shown in the third figure from the top of the Figure 1 shown.

[0073] The device can further comprise a second filling device (not shown). In the same way as the first PMMA-based mass 6, a fluid second PMMA-based mass 12 can be structured with the device using the base plate 1, the boundary wall 2, and the punch 7 with the heated, structured pressing surface 8 on one side. The fluid second PMMA-based mass 12 has a second color, for example, a dark tooth color, which differs from the color of the first PMMA-based mass 6. The structured second PMMA-based mass 12 can then be placed with its thus structured surface 14 onto the structured surface 10 of the first structured PMMA-based mass 6. This situation is shown in the fourth figure from the top of the Figure 1shown. Instead of using the stamp 7 with the pressing surface 8, a second stamp (not shown) with a differently shaped pressing surface can also be used, so that the second PMMA-based mass 12 receives a different surface structure than the first PMMA-based mass 6.

[0074] Optionally, at least one third PMMA-based mass (not shown) structured on two opposite sides can be inserted between the structured first PMMA-based mass 6 and the structured second PMMA-based mass 12. The structuring of the two opposing structured surfaces of the third PMMA-based mass can be carried out using two heated pressing surfaces arranged opposite one another. For this purpose, the base 1 can, for example, be replaced by another stamp (not shown) with a pressing surface, which is constructed analogously to the stamp 7 with the pressing surface 8, such as the stamp 27 according to Figure 2 .

[0075] Subsequently, the structured first PMMA-based mass 6 and the structured second PMMA-based mass 12, and optionally the at least one structured third PMMA-based mass arranged therebetween, can be joined together by pressing. For this purpose, a press 16 can be used, which presses the PMMA-based masses 6, 12 against each other and against the base plate 1. This situation is shown in the bottom figure after Figure 1 shown. A force between 1 and 10 tons can be applied.

[0076] After curing, a plastic body is created consisting of the two cured PMMA-based materials 6, 12 bonded together via the structured surfaces 10, 14. This plastic body can be removed from the device to produce dentures with a natural appearance using a subtractive process.

[0077] In this way, a multi-layered plastic body with a multitude of interlocking PMMA-based materials can be produced. The structuring creates a natural-looking interface between the PMMA-based materials, as in the Figures 8 and 9 is shown.

[0078] Figure 2 shows a schematic perspective view of a second heatable structured press plate for implementing a method according to the invention and Figure 3 shows a schematic detailed view of a press plate structured with the second Figure 2shaped surface of a PMMA-based mass 37. The structured pressing plate is a stamp 27. The stamp 27 can have a flat cylindrical shape. One side of the stamp 27 is designed as a heatable structured pressing surface 28, with which the PMMA-based mass 37 can be shaped. For this purpose, a plurality of four-sided pyramid-shaped peaks 29 can be arranged on the structured pressing surface 28. The pyramid-shaped peaks 29 are arranged as a periodic grid on the structured pressing surface 28. The stamp 27 can be made of a metal, such as stainless steel. In addition, an electrical resistance heater (not shown) can be arranged inside the stamp 27 or outside on its side opposite the structured pressing surface 28, with which the structured pressing surface 28 can be heated. The peaks of the pyramid-shaped peaks 29 protrude between 2 mm and 3 mm from their base.

[0079] The stamp 27 can be incorporated into a heating device, allowing thermostat-controlled heating of the pressing plates. With this configuration, the PMMA-based mass 37 can be structured. The PMMA-based mass 37 then has a structured surface 38, which is shaped as a negative of the structured pressing surface 28. Accordingly, the structured surface 38 has a plurality of periodically juxtaposed pyramid-shaped depressions 39. Several such structured PMMA-based masses 37 with different colors can be placed on top of one another with the structured surface 38 and subsequently pressed together.

[0080] Figure 4 shows a schematic detailed view as a detail enlargement of a structured surface 48 of a third heatable structured press plate 47 for implementing a method according to the invention and Figure 5a schematic cross-sectional view of the structure of the third structured press plate 47. The press plate 47 has a honeycomb structure in the form of honeycomb-shaped (hexagonal) depressions 49 that taper conically towards a bottom. A PMMA-based mass structured therewith therefore has a negative of the Figures 4 and 5 shown structured surface 48. The depth of the honeycomb-shaped depressions is between 2 mm and 3 mm.

[0081] Figure 6shows a schematic perspective partial view of a fourth heatable structured pressing plate 57 for implementing a method according to the invention. The structured pressing plate 57 is constructed like a stamp. One side of the structured pressing plate 57 can be designed as a circular, heatable structured pressing surface 58, with which a PMMA-based mass can be formed. For this purpose, a plurality of four-sided pyramid-shaped depressions 59 can be arranged on the structured pressing surface 58. The pyramid-shaped depressions 59 are arranged as a periodic square grid on the structured pressing surface 58. The pyramid-shaped depressions are between 2 mm and 3 mm deep. The structured pressing plate 57 can have a protruding edge 60 that encloses the structured pressing surface 58 at its edge. The structured pressing plate 57 can be made of a temperature-stable plastic, such as silicone.Additionally, an electrical resistance heater (not shown) can be arranged inside the structured pressing plate 57 or outside on the side of the structured pressing plate 57 opposite the structured pressing surface 58, with which the structured pressing surface 58 can be heated. Structured pressing plates 57 made of silicone are simpler and more cost-effective to manufacture. However, silicone as a material does not have the same fatigue strength and thus the same suitability for production as most metals, and in particular steel. Therefore, the construction of the structured pressing surfaces made of metal, and in particular steel, is preferred according to the invention.

[0082] Figure 7shows a schematic plan view of a structured surface 68 of a PMMA-based mass 67 formed with a heated structured press plate according to a method according to the invention. A plurality of pyramid-shaped depressions 69, arranged periodically next to one another in a square grid, protrude from the structured surface 68. The tips of the pyramid-shaped depressions 69 protrude between 2 mm and 3 mm from their base. Several PMMA-based masses 67 structured in this way, with different colors, can be placed on top of one another with the structured surfaces 68 and then pressed together.

[0083] Figure 8 shows an enlargement of a cross-section of an interface between two PMMA-based masses bonded together by a method according to the invention with different colors during short pressing and Figure 9shows an enlarged cross-section of another interface between two PMMA-based materials bonded together using a method according to the invention, with different coloration after a comparatively longer pressing period. The images were taken with a LEICA DMS 1000 microscope at four to six times magnification.

[0084] To produce the composite layer, standard dental material (Flexecure Dentin dental material, Kulzer GmbH) was pressed as the first PMMA-based material at a temperature of 115°C for a duration of between 20 s and 70 s at a pressure of approximately 100 kg on an area of ​​450 cm². The pressing was carried out using a structured pressing surface 38, as shown in detail in Figure 4 is shown.

[0085] Following pressing, the structured PMMA-based masses were combined, pressed and polymerized.

[0086] In the following, an exemplary procedure is described using the Figure 1 The sequence of the exemplary method is shown in the flow chart according to Figure 10 However, the description can easily be applied to other embodiments.

[0087] In a work step 100, a first fluid PMMA-based mass 6 having a first color can be provided. In parallel, in a work step 101, a second fluid PMMA-based mass 12 having a second color can be provided, and optionally, in a work step 102, at least one third fluid PMMA-based mass having a third color can be provided.

[0088] In a work step 103 following work step 100, the first fluid PMMA-based mass 6 can be applied to a surface, such as, for example, the surface of the base plate 1. Analogously, in a work step 104 following work step 101, the second fluid PMMA-based mass 12 can be applied to a surface, such as, for example, a surface of the base plate 1. Analogously, in a work step 105 following the optional work step 102, the at least one third fluid PMMA-based mass can be introduced between two structured, heated pressing surfaces.

[0089] In a work step 106 following work step 103, a surface 10 of the first PMMA-based mass 6 can be structured with the heated pressing surface 8. Similarly, in a work step 107 following work step 104, a surface 14 of the second PMMA-based mass 12 can be structured with the heated pressing surface 8 or another pressing surface, and optionally in a work step 108 following work step 105, two opposing surfaces of the at least one third PMMA-based mass can be structured with the two structured, heated pressing surfaces.

[0090] Subsequently, in a work step 109 following work step 106, the pressing surface 8 can be detached from the first PMMA-based mass 6. Likewise, in a work step 110 following work step 107, the pressing surface 8 or the other pressing surface can be detached from the second PMMA-based mass 12. In the optional phase of the process, in an optional work step 111 following optional work step 108, the two pressing surfaces can be detached from the at least one third PMMA-based mass.

[0091] Following these work steps, in a work step 112, the structured second PMMA-based mass 12 can now be arranged on the structured first PMMA-based mass 6, such that the two structured surfaces 10, 14 of the structured first PMMA-based mass 6 and the structured second PMMA-based mass 12 are aligned with one another. Alternatively, the at least one structured third PMMA-based mass can also be arranged between the structured first PMMA-based mass 6 and the structured second PMMA-based mass 12, such that the two structured surfaces 10, 14 of the structured first PMMA-based mass 6 and the structured second PMMA-based mass 12 are aligned with one another.

[0092] Subsequently, in a work step 113, all PMMA-based masses 6, 12 arranged on top of one another are pressed together and the PMMA-based masses 6, 12 are cured.

[0093] In a work step 114, the resulting, hardened and layered plastic body can be removed.

[0094] In an optional work step 115, at least one dental prosthesis can then be milled out of the hardened layered plastic body using a subtractive process, such as a CAM milling machine. List of reference symbols

[0095] 1Bottom plate 2Boundary wall 3Filling device 4Pipe 5Container 6PMMA-based mass 7Pump 8Structured pressing surface 9Pump 10Structured surface 12Second PMMA-based mass 14Structured surface 16Press 27Pump 28Structured pressing surface 29Pyramidal tips 37Structured PMMA-based mass 38Structured surface 39Pyramidal depression 47Press plate 48Structured pressing surface 49Honeycomb depression 57Press plate 58Structured pressing surface 59Pyramidal depression 60Edge 67Structured PMMA-based mass 68Structured surface 69Pyramidal depression 70First PMMA-based mass 72Second PMMA-based mass 74Interface 80First PMMA-based mass 82Second PMMA-based mass 84Interface 100Work step: Providing a first fluid PMMA-based mass with a first color 101Work step: Providing a second fluid PMMA-based mass with a second color 102Optional work step:Providing at least one third fluid PMMA-based mass with a third color 103 Work step: Applying the first fluid PMMA-based mass to a surface 104 Work step: Applying the second fluid PMMA-based mass to a surface 105 Optional work step: Introducing the at least one third fluid PMMA-based mass between two structured heated pressing surfaces 106 Work step: Structuring a surface of the first PMMA-based mass with a heated pressing surface 107 Work step: Structuring a surface of the second PMMA-based mass with a heated pressing surface 108 Optional work step: Structuring two opposite surfaces of the at least one third PMMA-based mass with the two structured heated pressing surfaces 109 Work step: Detaching the pressing surface from the first PMMA-based mass 110 Work step: Detaching the pressing surface from the second PMMA-based mass 111 OptionalWork step: Detaching the two pressing surfaces from the at least one third PMMA-based mass 112 Work step: Arranging the structured second PMMA-based mass on the structured first PMMA-based mass such that the two structured surfaces of the structured first and second PMMA-based masses are aligned with each other, or arranging the at least one structured third PMMA-based mass between the structured first PMMA-based mass and the structured second PMMA-based mass such that the two structured surfaces of the structured first and second PMMA-based masses are aligned with each other 113 Work step: Pressing all PMMA-based masses arranged on top of each other and curing the PMMA-based masses 114 Work step: Removing the cured layered plastic body 115 Optional work step: Manufacturing at least one dental prosthesis from the cured layered plastic body

Claims

1. A method for producing a plastics body with patterned layers for producing dental prostheses, wherein the method having the following steps: A) providing a first PMMA-based compound (6, 37, 67, 70, 80) and a second PMMA-based compound (12, 37, 67, 72, 82), wherein the first PMMA-based compound is uncured and has a first coloration and wherein the second PMMA-based compound is uncured and has a second coloration, wherein the second coloration of the second PMMA-based compound differs from the first coloration of the first PMMA-based compound; B) heating of a first patterned pressing surface (8, 28, 48, 58) to a temperature of between 90°C and 150°C; C) pressing of the first PMMA-based compound with the heated first patterned pressing surface, wherein a patterned surface (10, 38, 68) of the first PMMA-based compound is obtained in this manner; D) subsequent detachment of the first pressing surface from the patterned first PMMA-based compound, wherein the patterned surface of the first PMMA-based compound is retained; and E) heating of the first patterned pressing surface to a temperature of between 90°C and 150°C or heating of a second patterned pressing surface (8, 28, 48, 58) to a temperature of between 90°C and 150°C; F) pressing of the second PMMA-based compound with the heated first patterned pressing surface or the heated second patterned pressing surface, wherein a patterned surface (14, 38, 68) of the second PMMA-based compound is obtained in this manner; G) subsequent detachment of the first pressing surface or the second pressing surface from the patterned second PMMA-based compound, wherein the patterned surface of the second PMMA-based compound is retained; H) subsequent laying of the patterned second PMMA-based compound on the patterned first PMMA-based compound, such that the patterned surface of the second PMMA-based compound is oriented toward the patterned surface of the first PMMA-based compound; and I) subsequent compression molding of the first patterned PMMA-based compound with the second patterned PMMA-based compound, such that a solid bond is created between the first PMMA-based compound and the second PMMA-based compound.

2. The method according to Claim 1, characterized by step J) curing of the patterned first PMMA-based compound and the second PMMA-based compound compression molded therewith, wherein step J) preferably proceeds after step I).

3. The method according to any one of the preceding claims, characterized in that pressing of an uncured third PMMA-based compound proceeds with two heated patterned pressing surfaces arranged opposite one another, wherein a patterned surface is consequently obtained on both sides of the third PMMA-based compound, wherein the third PMMA-based compound has a third coloration which differs from the first coloration of the first PMMA-based compound and from the second coloration of the second PMMA-based compound, subsequent detachment of the pressing surfaces from the third PMMA-based compound patterned on both sides, wherein the two patterned surfaces of the third PMMA-based compound are retained, wherein in step H) the patterned third PMMA-based compound is arranged between the patterned second PMMA-based compound and the patterned first PMMA-based compound, such that the patterned surfaces lie against one another, and wherein in step I) subsequent compression molding of the first patterned PMMA-based compound with the second patterned PMMA-based compound and with the third patterned PMMA-based compound arranged therebetween proceeds such that a solid bond is created between the first PMMA-based compound, the second PMMA-based compound and the third PMMA-based compound.

4. The method according to Claim 1 or 2, characterized in that in step H) overall a plurality of further PMMA-based compounds are arranged between the first patterned PMMA-based compound and the patterned second PMMA-based compound, wherein the colorations of adjacent PMMA-based compounds of the first, second and plurality of PMMA-based compounds preferably differ from one another, wherein before step H) each of the plurality of further PMMA-based compounds is patterned with two heated patterned pressing surfaces arranged opposite one another, wherein a patterned surface is consequently obtained on both sides of the plurality of further PMMA-based compounds, and the pressing surfaces are subsequently detached from the plurality of further PMMA-based compounds patterned on both sides, wherein the two patterned surfaces of the plurality of further PMMA-based compounds are retained, in step I) subsequent compression molding of the first patterned PMMA-based compound with the second patterned PMMA-based compound and with the plurality of further patterned PMMA-based compounds arranged therebetween proceeds such that a solid bond is created between the first PMMA-based compound, the second PMMA-based compound and the plurality of further PMMA-based compounds arranged therebetween.

5. The method according to any one of the preceding claims, characterized in that pressing of the first PMMA-based compound in step C) with the heated first patterned pressing surface and pressing of the second PMMA-based compound in step F) with the first patterned pressing surface or with the second heated patterned pressing surface proceeds with a pressure of between 10 kN / m2 and 500 kN / m2, preferably with a pressure of between 10 kN / m2 and 100 kN / m2, particularly preferably with a pressure of between 10 kN / m2 and 50 kN / m2.

6. The method according to Claim 3 or 4, characterized in that pressing of the third PMMA-based compound or of the further PMMA-based compounds with the two heated patterned pressing surfaces arranged opposite one another proceeds with a pressure of between 10 kN / m2 and 500 kN / m2, preferably with a pressure of between 10 kN / m2 and 100 kN / m2, particularly preferably with a pressure of between 10 kN / m2 and 50 kN / m2.

7. The method according to any one of the preceding claims, characterized in that pressing of the first PMMA-based compound in step C) with the heated first patterned pressing surface and pressing of the second PMMA-based compound in step G) with the heated first patterned pressing surface or with the heated second patterned pressing surface proceeds for a period of between 1 s and 50 s, preferably for a period of between 5 s and 30 s, wherein preferably and if present, pressing of the third PMMA-based compound or of the plurality of further PMMA-based compounds with the two heated patterned pressing surfaces arranged opposite one another proceeds for a period of between 1 s and 50 s, preferably for a period of between 5 s and 30 s.

8. The method according to any one of the preceding claims, characterized in that the first patterned pressing surface and / or the second patterned pressing surface is or are heated during pressing, preferably all the patterned pressing surfaces used are heated during pressing.

9. The method according to any one of the preceding claims, characterized in that the first patterned pressing surface and / or the second patterned pressing surface, preferably all the patterned pressing surfaces used, have patterns with a profile height of between 1 mm and 5 mm, preferably with a profile height of between 2 mm and 3 mm.

10. The method according to any one of the preceding claims, characterized in that a pressure of between 10 kN / m2 and 500 kN / m2, preferably of between 10 kN / m2 and 50 kN / m2 is applied for the compression molding in step I).

11. The method according to any one of the preceding claims, characterized in that the first patterned pressing surface and / or the second patterned pressing surface, preferably all the patterned pressing surfaces used, have a honeycomb pattern or a plurality of peaks projecting from the pressing surface or a plurality of pyramidal or conical protrusions projecting from the pressing surface, wherein the projecting peaks or the projecting pyramidal or conical protrusions are preferably arranged periodically in the pressing surface.

12. The method according to any one of the preceding claims, characterized in that the first patterned pressing surface and / or the second patterned pressing surface, preferably all the patterned pressing surfaces used, consist of silicone or are coated with silicone or consist of a metal, in particular of a stainless steel, wherein the metal is preferably coated, particularly preferably coated with Teflon or silicone.

13. The method according to any one of the preceding claims, characterized in that the PMMA-based compounds have a viscosity of between 1 Pa·s and 1000 Pa·s at their time of use and at a temperature of 20°C.

14. A method for producing dental prostheses, wherein the method comprises a method according to any one of the preceding claims and the method is additionally characterized by the following step: K) carving out of a dental prosthesis or a plurality of individual dental prostheses from the completely cured plastics body after method steps A) to I) and optionally J), wherein a tooth axis of the dental prosthesis or tooth axes of the plurality of individual dental prostheses extends or extend from a basal end of the dental prosthesis or dental prostheses, wherein the dental prosthesis or the dental prostheses are subtractively carved out from the plastics body in such a manner that the tooth axis or the tooth axes extends or extend through a plurality of layers of the PMMA-based compounds of the plastics body and wherein carving out preferably proceeds with the assistance of a subtractive CAM process.

15. A device for implementing a method according to any one of the preceding claims, the device comprising at least one patterned pressing surface (8, 28, 48, 58) and a base plate (1), wherein the at least one patterned pressing surface (8, 28, 48, 58) is heatable, and / or at least two patterned pressing surfaces (8, 28, 48, 58) arranged opposite one another which are heatable, at least two containers (5) containing at least two differently colored fluid PMMA-based compounds (6, 12, 37, 67, 70, 72, 80, 82) or at least two containers (5) containing the starting components for producing at least two differently colored fluid PMMA-based compounds (6, 12, 37, 67, 70, 72, 80, 82), and a press (16) for compression molding together at least two patterned PMMA-based compounds (6, 12, 37, 67, 70, 72, 80, 82) stacked on one another.

16. The device according to Claim 15, characterized in that the device has a circumferential boundary wall (2) which is arranged on the base plate (1) and in which the at least one patterned pressing surface (8, 28, 48, 58) is movable or which is arranged around the at least two patterned pressing surfaces (8, 28, 48, 58) arranged opposite one another.

17. The device according to Claim 15 or 16, characterized in that the device additionally has at least one filling means (3) for applying the fluid PMMA-based compounds (6, 12, 37, 67, 70, 72, 80, 82) onto the base plate (1) or between the two patterned pressing surfaces (8, 28, 48, 58) arranged opposite one another, wherein the at least one filling means (3) is preferably suitable and provided for filling the PMMA-based compounds (6, 12, 37, 67, 70, 72, 80, 82) within the circumferential boundary (2).