Method for producing large polymerized dental material blocks

Abstract

Method for producing a three-dimensional dental material block from a dental, polymerizable material, wherein the material block is suitable for the production of dental prosthetic parts in a material-absorbing process, comprising the steps a) optional: adjusting the viscosity, b) Transferring the polymerizable dental material into a radiolucent three-dimensional casting or pressing mold, c) Planarizing at least one surface of the dental material in the three-dimensional casting or pressing mold to form a defined three-dimensional geometry of the material, wherein planarization is carried out by applying a transparent film or a planar transparent disc to the material to be polymerized in a three-dimensional casting or pressing mold open on one side, and the film or disc is subsequently subjected to pressure with a punch to planarize the surface, and / or d) Applying pressure to the polymerizable material in the three-dimensional casting or pressing mold by subjecting the polymerizable material to a pressure of 1.5 to 5 bar, e) Irradiation of the polymerizable dental material substantially from all sides with light in the UVNis range, forming polymerized outer surfaces of the dental material in the form of a solid outer shell of the dental material, wherein the shell is present in the defined three-dimensional geometry of the material, while the inner area of ​​the material is not polymerized or partially polymerized. f) optional removal of the dental material with a dimensionally stable shell with defined three-dimensional geometry from the casting or pressing mold, g) Heating the material with a solid shell, which is in a defined three-dimensional geometry, to 60 °C to 150 °C for at least 90 minutes, h) optional: Cooling of the fully polymerized material, i) Obtaining a dental, polymerized material block with a defined three-dimensional geometry.

Description

[0001] The invention relates to a method for the stress-free polymerization of larger three-dimensional dental material blocks according to claim 1, which are suitable for the production of dental prosthetic parts in a material-removing process and obtaining a material block which is substantially free of voids and is obtained substantially while maintaining the three-dimensional geometry established before the polymerization, in particular the substantially complete polymerization.

[0002] The state of the art is to use small blocks of material with a base area of ​​1 cm 2 and approximately 3 to 4 cm long, which are cured for a few seconds on both long sides. Alternatively, light curing in a water bath over a longer period of time has been disclosed.

[0003] When manufacturing composite milling discs from highly filled light-curing composites such as Charisma, Venus Diamond, Signum Ceramis, or Venus Pearl, it is to be expected that cracks and fissures will often occur during heat-curing alone due to tensions in the material, especially when producing blocks of a certain size. Light-curing is not an option due to the high layer thickness of the milling blank and the insufficient curing depth of the light-curing composite.

[0004] The object of the invention was to develop a process that allows the production of dental material blocks or material plates of a certain dimension that can be divided or cut into a plurality of small material blocks from which dental prostheses or parts thereof can be produced by means of a material-removing process. Likewise, a process was to be developed with which essentially stress-free dental material blocks can be produced, which are preferably free of stress-induced defects such as cracks. Furthermore, a process for the production of dental prosthetic composite milling blanks, in particular with a filler content of 50 to 95 wt. %, was to be developed in which stress-induced defects such as shrinkage cavities, cracks and fissures in the milling block do not occur during the production process.

[0005] WO2011 / 041182A1 relates to the production of multilayer dental articles in different casting molds. DE699 22 413 T2 relates to milling blanks in which cracks and discontinuities are found to be less than 1 mm, as well as a method for producing them. DE 601 30 139 T2 relates to a method in which filling material reacts with a second mold component, creating a chemical bond, and to a milling blank assembly with a holder. US 2013 / 0049241 A1 discloses a dental molded part and its production.

[0006] The objects were achieved by a method according to claim 1 and by the dental material blocks obtainable by the method according to claim 9 as well as by the use of a casting or pressing mold in this method according to claim 10 and the use of the dental material blocks according to claim 11.

[0007] The objects were achieved according to the invention by placing a polymerizable dental material, such as preferably a dental composite, into a casting or pressing mold that is translucent at the wavelength of the photoinitiator(s), and curing it therein in a combined process of specific light-induced polymerization and defined thermal polymerization according to claim 1. It is advantageous if the dental material, such as a composite, is heated to a temperature at which the viscosity of the material is significantly reduced before being poured into the casting or pressing mold. This measure allows the dental material to flow better into the casting or pressing mold and fill the mold more completely. The selected temperature must be below the temperature at which the thermally induced polymerization starts.Therefore, the temperature selected for adjusting the viscosity depends on the thermal polymerization initiator used. When using dibenzoyl peroxide, for example, the dental material can be processed at a maximum of approximately 60–65°C for a maximum of two hours.

[0008] After flowing into the transparent three-dimensional casting or pressing mold, particularly into the hollow mold of the casting or pressing mold, the surface is planarized or smoothed by carefully pressing the surface with a planar stamp, so that the material acquires a defined three-dimensional geometry. The polymerizable material in the transparent casting or pressing mold can then be irradiated from all sides for 6 minutes with a suitable light source, such as a laboratory light lamp, preferably in a light oven such as an Egger light oven. Irradiation with UV / Vis light polymerizes or partially cures the material on the surface. Light curing corresponds to a pre-curing process in which an outer polymerized, closed shell forms in the dental material. The polymerized, cured shell of the dental material has a thickness of polymerized material of approximately 3 to 5 mm.However, the core of the dental material is still soft. The dental material is then removed from the mold, preferably with the outer shell closed. In the next step, the dental material, especially the composite material, is thermally polymerized for approximately 8 hours in an oven, such as a drying cabinet, at approximately 90°C to complete the thermal curing and thus the hardening of the milling block. The resulting material block is preferably fully polymerized.

[0009] The invention relates to a method for producing a three-dimensional dental material block, in particular a dental composite block, from a dental, polymerizable material, as well as a material block obtainable by the method, wherein the material block is suitable for producing dental prosthetic parts in a material-removing process, and the method comprises the steps a) optional: adjusting the viscosity, in particular to obtain a flowable material, b) transferring the polymerizable dental material into a radiolucent three-dimensional casting or pressing mold, in particular with a hollow mold, in particular into a PMMA or polycarbonate casting or pressing mold, preferably with a wall thickness of at least 5 mm to 30 mm, preferably 5 to 10 mm wall thickness, and preferably with the formation of a defined three-dimensional geometry of the material, c) Planarising at least one surface of the dental material in the three-dimensional casting or pressing mould, in particular in a mould open on one side, to form a defined three-dimensional geometry of the material, wherein the planarisation is carried out by applying a transparent film or a planar transparent disc to the material to be polymerised in a three-dimensional casting or pressing mould open on one side, and the film or disc is then subjected to pressure with a stamp to planarise the surface, and / or d) applying pressure to the polymerisable material in the three-dimensional casting or pressing mould, in particular the material is pressurised with a gas or gas mixture at a pressure of 1.5 to 5 bar, e) irradiating the polymerizable dental material from all sides with light in the UV / Vis range, in particular the material is irradiated with light from all sides simultaneously, forming polymerized outer surfaces of the dental material in the form of a solid outer shell of the dental material, wherein the shell is present in the defined three-dimensional geometry of the material, in particular of step b) or c), while the inner region of the material is not polymerized and / or partially polymerized, f) optionally removing the dental material with a dimensionally stable shell with a defined three-dimensional geometry from the casting or pressing mold, g) heating the material with a solid shell and defined three-dimensional geometry to 60 °C to 150 °C for at least 90 minutes, in particular at 70 to 95 °C for 6 to 10 hours, h) optionally cooling the fully polymerized material, i) Obtaining a dental, polymerized material block with a defined three-dimensional geometry. The polymerized material block is preferably fully polymerized.

[0010] In step b), the polymerizable dental material is preferably transferred into a radiolucent three-dimensional casting or pressing mold, wherein the casting or pressing mold preferably has at least a first edge length or a diameter of greater than or equal to 90 mm and at least a second and / or third edge length of greater than or equal to 20 mm of the mold for producing the material block, preferred molds are at least 148 x 210 mm, preferably at least 210 x 297 mm and for producing a material thickness / height of at least 20 mm, preferably 30 mm, 90 to 200 mm.

[0011] In step e), the light source and / or the casting or pressing mold can rotate to enable uniform irradiation from all sides of the mold. The irradiation in step e) can preferably take place without separate cooling in a medium such as water. Irradiation preferably takes place from all sides simultaneously for at least 5 minutes to 60 minutes, preferably from all sides simultaneously for 5 to 15 minutes. The pretreatment according to the invention enables crack-free irradiation without simultaneous cooling. The shell obtained in step e) generally has a wall thickness of 3 to 5 mm, so that after irradiation in step e), the shell has the defined three-dimensional geometry of the material, while the inner region of the material is unpolymerized or partially polymerized. In step e), a dimensionally stable dental material with a shell in a defined three-dimensional geometry is preferably obtained.

[0012] The material blocks according to the invention should, on the one hand, be easy to cut and also be suitable for the production of dental prosthetic parts using a material-removing process, such as a milling process and / or grinding, drilling, material removal using laser energy, such as laser milling, by chipping off the material, and / or CAD / CAM milling and / or a process comprising various material-removing process steps. It is particularly preferred if the material-removing processes are CAD / CAM processes in which the material-removing processing is automated.

[0013] In order to convert the material blocks into an optimal geometry before polymerization, it has proven advantageous to planarize the polymerizable material transferred into the casting or pressing mold that is open on one side, in particular on the upper side. Therefore, planarization is preferably carried out in step c) by applying a film or a planar disc, both of which are preferably transparent, to the material to be polymerized in the three-dimensional casting or pressing mold that is open on one side. The film or disc is then subjected to pressure using a stamp to planarize the surface. The stamp used for planarization is preferably pressed onto the material at a pressure of at least 1 bar, preferably under a pressure of 1.2 to 5 bar, more preferably planarization is carried out using a stamp at a pressure of 2 to 5 bar.For this purpose, the stamp preferably has a geometry adapted to the casting or pressing mold with a planar underside.

[0014] To homogenize the dental polymerizable material prior to light-induced polymerization, the material is pressurized with a gas or gas mixture. Accordingly, it is preferred if, in step d), the polymerizable material in the three-dimensional casting or pressing mold is pressurized with a pressure, in particular a gas or gas mixture, of 1.5 to 5 bar; preferably, a pressure of 2 to 5 bar is used, particularly preferably 2 to 3 bar. The polymerizable material is treated with a gas or gas mixture under elevated pressure in order to minimize or eliminate any gaseous microinclusions, e.g., of air or gas, present in the material. Preferred gases or gas mixtures for treating the material under pressure include air, helium, and argon, with air being particularly preferred.

[0015] According to a particularly preferred embodiment of the invention, the irradiation of the polymerizable dental material is carried out essentially from all sides with light in the UV / Vis range in the range of approximately 380 nm - 500 nm, preferably as dual irradiation in the UV and Vis range, preferably the irradiation is carried out simultaneously from all sides of the three-dimensional geometry, for a period of time greater than or equal to 4 minutes to 4 hours, in particular greater than or equal to 5 minutes, preferably 5.5 minutes to 15 minutes.

[0016] The invention also relates to a method in which the irradiation of the polymerizable dental material takes place as dual irradiation and the at least two intensity maxima of the light from the radiation source(s) are in the UV and Vis range, in particular irradiation takes place with intensity maxima of the radiation source(s) from 350 nm to 390 nm and from 420 nm to 500 nm, particularly preferably with intensity maxima around 380 nm and 450 nm, preferably + / - 20 nm. In order to obtain a qualitatively particularly good and uniform polymerization of the outer shell, dual irradiation is particularly suitable.It is further particularly preferred if the irradiation takes place in a light oven, in particular in an internally mirrored light oven, particularly preferably in a light oven in which two to 20 radiation sources, preferably 4 to 15 radiation sources, with at least two intensity maxima of the radiation source(s) from 350 nm to 390 nm and from 420 nm to 500 nm, particularly preferably with intensity maxima around 380 nm and 450 nm. Particularly suitable radiation sources in an internally mirrored light oven are: 2 - 20 radiation sources with 9W each (450 nm) and 2 to 20 radiation sources with 9W each (380 nm).

[0017] The irradiation in step e) forms a preferably outer, closed shell of the polymerized material in the three-dimensional geometry of the dental material. The dental material with the shell is preferably dimensionally stable and has a defined three-dimensional geometry that approximately corresponds to the casting or pressing mold. The shell preferably has a thickness of greater than or equal to 2 to 15 mm; preferably, the shell has a thickness of polymerized material of greater than or equal to 2 to 10 mm, particularly preferably 3 to 6 mm, and further preferably 3 to 4 mm.

[0018] In one process step, e.g., f), the dental material is preferably removed from the casting or pressing mold with a dimensionally stable shell and a defined three-dimensional geometry. Alternatively, the subsequent thermal treatment can also take place in the casting or pressing mold.

[0019] In one process step, e.g. j), the dental, polymerized material block obtained in i) with a defined three-dimensional geometry is divided into greater than or equal to 50 milling blocks, each having at least one edge length of greater than or equal to 10 mm, in particular less than or equal to 25 mm, preferably less than or equal to 20 mm. Preferably, two to three edge lengths of the cuboid-shaped milling blocks are greater than or equal to 10 mm. The division can be carried out by shearing, laser cutting, sawing or other measures known to the person skilled in the art. It is particularly preferred if the material block is divided into greater than or equal to 90 milling blocks, preferably greater than or equal to 160 milling blocks, each having at least one edge length of greater than or equal to 10 mm, and in particular less than or equal to 20 mm, preferably less than or equal to 25 mm. The milling blocks are preferably in the form of cuboids.Preferably, all edge lengths of the cuboids are greater than or equal to 10 mm, especially greater than or equal to 12 mm, and less than or equal to 25 mm. Thus, milling blocks can be produced in the form of cuboids with an area of ​​14 x 14 mm or 15 x 15 mm and a height of 17 to 18 mm.

[0020] In process step g), the material from step e) with a solid shell and defined three-dimensional geometry is heated to 60°C to 150°C for at least 90 minutes. The thermal polymerization is preferably carried out in the temperature range from 70°C to 100°C, preferably from 70 to 95°C, particularly preferably from 80°C to 95°C, further preferably from 85 to 95°C, preferably around 90°C + / - 2.5°C. The thermal polymerization is carried out in the aforementioned temperature range for greater than or equal to 2 hours, preferably from 2 to 12 hours. In particular, at 70°C to 95°C for 2 to 12 hours. In order to produce particularly stress-free material blocks, in particular material blocks with an edge length of greater than or equal to 90 mm and at least a second edge length of greater than or equal to 20 mm, a thermal treatment of 80 to 95 °C for 5 to 12 hours has proven to be effective, in particular for 7 to 9 hours, preferably for 8 hours at 90 °C + / - 2.5 °C.According to a particularly preferred alternative, in step g) heating is carried out at 70 °C to 95 °C for 2 to 12 hours, in particular the dental material in step g) is heated in an oven.

[0021] Following the thermal polymerization step, in step h), the material can cool in the furnace for a defined period of time. To produce particularly stress-free material blocks, it is preferred if the cooling takes place in the furnace, which is then shut down after step g). Preferably, the furnace is shut down, allowing the material to cool slowly in the furnace.

[0022] The optional adjustment of the viscosity before transferring the dental polymerizable material into the casting or pressing mold can be achieved by heating the material to 60 to 65 °C. In any case, the temperature for adjusting the viscosity should be below the temperature at which the thermally induced polymerization is started. Preferably, the temperature is at least 10 °C below the temperature at which the thermally induced polymerization starts. The dental material can preferably have the following viscosity or be adjusted to a viscosity with η of 1 10 5 Pa · s to 5.0 · 10 8 Pa · s, preferably a viscosity of f η of 5 · 10 5 Pa s up to 2.0 10 8 Pa · s, particularly preferably η of 8 · 10 5 Pa s up to 2.0 10 8 Pa · s. The storage modulus of the polymerizable material can be between G* = 2 · 10 3 up to 10 · 10 5lay.

[0023] To produce the material blocks according to the invention, casting or pressing molds, in particular with a hollow mold, made of PMMA (polymethyl methacrylate) or polycarbonate (PC) are preferably used. The molds can be cylindrical PMMA casting or pressing molds, in particular with a hollow mold, with a PMMA base, e.g. in the form of cylindrical shells made of PMMA. The molds can also have rectangular or square dimensions in plan view. Suitable, for example, are casting or pressing molds with at least one hollow mold that are in the shape of a cuboid in which two surfaces are larger than or equal to DIN A5, in particular larger than or equal to DIN A4, and the remaining edge length is at least 20 mm, preferably larger than or equal to 30 mm, larger than or equal to 40 mm, 50 mm, or larger than or equal to 60 mm. It is also possible to produce cuboids in which at least four surfaces are larger than or equal to DIN A5, in particular larger than or equal to DIN A4.Other suitable geometries for the hollow form in casting or compression molds include cylindrical, rod-shaped, or cube-shaped shapes. Alternatively, the casting or compression mold can be made of another transparent material such as polycarbonate.

[0024] The hollow mold can preferably correspond to the three-dimensional, defined geometry of the shell with a defined three-dimensional geometry of the material, preferably the geometry of the dental, polymerized material block with a defined three-dimensional geometry. It is particularly preferred if the material block with a defined three-dimensional geometry has a volume shrinkage of less than or equal to 1-3 vol% relative to at least one edge length of the hollow mold.

[0025] The process is particularly preferably carried out using casting or compression molds with a transparency of greater than 95%, in particular made of PMMA or polycarbonate or glass, such as quartz glass or commercially available glass. According to a particularly preferred alternative, the process according to the invention is carried out using casting or compression molds whose material has a refractive index of 1.3 to 1.8, in particular 1.48 to 1.50.

[0026] The wall thickness of the casting or compression molds used in the process should preferably be in the range of 5 to 30 mm, more preferably 5 to 10 mm. Irradiation preferably takes place directly in the PMMA or polycarbonate casting or compression mold, in particular without the use of a water bath, without water cooling of the casting or compression mold, or any other cooling medium surrounding the casting or compression mold.

[0027] According to the method according to the invention, material blocks with a defined three-dimensional geometry can be produced or are obtainable which essentially have no gaseous microinclusions or voids larger than 0.05 mm, preferably the voids or gaseous microinclusions are less than or equal to 100 µm, particularly preferably less than or equal to 50 µm, further preferably less than or equal to 20 µm.

[0028] The polymerized material blocks with a defined three-dimensional geometry produced or obtainable by the process according to the invention preferably have at least one first edge length or a diameter greater than or equal to 90 mm and preferably have at least one second edge length greater than or equal to 20 mm, in particular greater than or equal to 90 mm to 200 mm. In particular, cuboids can be obtained in which two surfaces are greater than or equal to DIN A5 (21 cm × 14.8 cm) or greater than or equal to DIN A4 (21 cm × 29.7 cm) and the remaining edge lengths are greater than or equal to 20 mm, preferably greater than or equal to 30 mm, and more preferably greater than or equal to 40 to 60 mm.

[0029] In the method according to the invention, a composite material can be used as the dental polymerizable material, which comprises (i) 50 to 95 wt.% inorganic fillers comprising a) silicon dioxide, preferably silicic acid; zirconium dioxide and / or mixtures comprising at least the two aforementioned oxides, and b) dental glasses whose average particle sizes are in the range of 0.2 to 10 µm, (ii) 5 to 50 wt.% monomer mixture, (iii) 0 to 2 wt.% of initiators comprising photoinitiators, at least one thermally activatable radical initiator, such as peroxides, (iv) 0 to 2 wt% stabilizers, additives, the total composition being 100 wt%.

[0030] According to a preferred alternative, the dental glasses can be present with at least two different fractions of average particle sizes in the range of 0.2 to 10 µm.

[0031] The invention also relates to a dental material block which has no cavities, cracks, or voids with a dimension greater than or equal to 0.05 mm, preferably less than or equal to 100 µm, particularly preferably less than or equal to 50 µm, further preferably less than or equal to 20 µm. The invention also relates to a material block which has at least one first edge length or a diameter of greater than or equal to 90 mm and at least one second edge length of greater than or equal to 20 mm. Material blocks measuring 148 x 210 mm, preferably 210 x 297 mm, and a material thickness / height of at least 20 mm, preferably 30 mm, 90 to 200 mm are preferred.

[0032] The polymerized material block is further characterized in that it has substantially the same defined geometry as the polymerizable dental material in the casting or pressing mold, in particular in step c), d) and / or e), in particular in step c) or d). Thus, the polymerized material block preferably has approximately the same geometry as the recess of the casting or pressing mold, wherein the height of the material block on the side on which the planarization took place can vary.

[0033] Through the prolonged light curing according to the invention, preferably for at least 4 minutes simultaneously from all sides, the polymerizable dental material acquires a solid, dimensionally stable outer shell, which already has the defined three-dimensional geometry of the material. Therefore, according to the invention, the dental material with the solid shell can be removed from the casting and / or pressing mold and subsequently thermally treated in the oven.

[0034] Preferably, the polymerized material block, relative to the polymerizable dental material in the defined geometry in step c) or d), exhibits a shrinkage of less than 1-3 vol% with respect to the first edge length or a diameter of 90 mm. A shrinkage of less than or equal to 1-3 vol% with respect to the second edge length of greater than or equal to 20 mm is also preferred.

[0035] The invention also relates to the use of a polymerized block of material which has at least one edge length or a diameter of greater than or equal to 90 mm and at least a second edge length of greater than or equal to 20 mm for producing at least two smaller blocks of material, in particular by dividing the block of material at least once, preferably by cutting, sawing or dividing it by other measures known to those skilled in the art. According to the method of the invention, DIN A5 or DIN A4 sized sheets with a thickness of 10 to 50 mm, preferably 20 to 50 mm, can be produced, which can then be divided, for example, into milling blocks in the form of cuboids with an area of ​​14 x 14 mm or 15 x 15 mm and a height of 17 to 18 mm. In this way, over 200 smaller blocks of material for use as a milling block can be produced from one DIN A4 sized sheet, for example over 200 smaller material blocks or milling blocks can be cut.

[0036] The material blocks produced according to the invention or the material blocks that can be produced from them can then be processed in an abrasive process to form dental prosthetic parts or parts thereof, in particular composite blocks can be produced and processed in a CAD / CAM process by milling, drilling and / or by means of a laser in an abrasive process, such as laser milling.

[0037] Embodiments explain the invention in more detail without limiting the invention to these objects. Fig. 1: A translucent PMMA casting or pressing mold according to the invention. Fig. 2: PMMA mold filled with polymerizable dental material. Fig. 3: Planarizing the surface of the material Fig. 4: All-round light curing with formation of the shell in the polymerizable material. Fig. 5: Polymerized material block. Fig. 6: Bridge milled from the material block Fig. 7a and Fig. 7b: non-inventive material blocks of the same material that was purely thermally cured. Fig. 8: Representation of a cut material block according to the invention with different magnifications of the cut surface.

[0038] Fig. Figure 1 shows a PMMA casting or pressing mold according to the invention, which is open at one side to allow the polymerizable dental material to flow in or be introduced as a kneadable paste. Fig. 2 shows the PMMA mold filled with a polymerizable dental material. Fig.3, the dental material in the PMMA mold is planarized with a stamp on the top side by pressing the stamp onto the surface of the polymerizable material with a defined pressure. Preferably, a transparent film or a transparent planar disc, preferably made of PMMA, is placed between the stamp and the surface of the polymerizable material. Subsequently, the material is pressurized with a gas or gas mixture in a pressure vessel to eliminate gaseous micro-inclusions. Light curing on all sides is required. Fig. 4. After light curing, the thermal polymerization according to the invention takes place at 90 °C for 8 hours. The resulting polymerized material block is shown in Fig. 5 and in Fig. 6 shown.

[0039] Fig. 7a and Fig.7b: Non-inventive material blocks of the same material that were cured by annealing the material for 8 hours at 90 °C. The cured material exhibits large cracks or cavities larger than 0.5 cm. Overall, it is also noticeable that the polymerized material blocks do not exhibit their original, defined geometry after annealing, but are significantly distorted. The top view clearly shows that the material blocks no longer exhibit their original circular geometry.

[0040] Fig.Figure 8 shows a sectioned block of material and various sections (1, 2, 3, 4, and 5) at 200x magnification, as well as a larger section at 5x and 20x magnification. Figures 1 to 5 show the scale for 200 micrometers. The magnifications show that the block of material hardened using the inventive method, despite its large dimensions of over 90 mm wide, exhibits no distortions, gaseous inclusions, or cavities, whereas the purely thermally hardened blocks of the same dimensions are inherently distorted and exhibit large cracks and cavities. Example:

[0041] According to the invention, this object is achieved by placing the composite in a mold that is translucent at the wavelength of the photoinitiator. Advantageously, the composite is first heated to a temperature at which the viscosity of the material is significantly reduced, in order to facilitate better flow into the mold. However, the temperature must not be so high that thermally induced polymerization begins. This depends on the thermal polymerization initiator used. When using, for example, dibenzoyl peroxide, maximum temperatures of approximately 60–65°C for a maximum period of 2 hours have proven to be advantageous.

[0042] After flowing into the transparent mold and leveling the surface through careful pressing, the material is irradiated on all sides in a suitable laboratory light lamp, such as an Egger light oven, for 6 minutes, and the surface is partially cured. After this pre-curing process, the material is covered by a partially cured "skin" of approximately 5 mm, although the core is still soft. The dimensionally stable, light-cured composite material is removed from the PMMA mold and then placed in a drying cabinet at approximately 90°C for approximately 8 hours to complete the thermal curing and thus the hardening of the milling block.

[0043] UV / Vis: 380 nm to 500 nm for 6 minutes, at 23°C ambient temperature; 5 tubes of Osram dulux S-Blue 71 blue 9W (450 nm) and 5 tubes of Osram dulux S-Blue 78 blue 9W (380 nm), particularly in a light oven with an internal mirror; Thermal polymerization: in a preheated oven at 90°C for 8 hours. Cooling took place in the oven, which was then switched off. Comparison of material parameters Test specimen made of light-curing paste Test specimen milled from milling block manufactured according to the invention charisma Charisma + Peroxide Flexural strength [MPa] 144 145 Young's modulus [MPa] 9543 11747 Hardening 8 min. both sides Palatray CU 6 min. Egger light oven and 8 h 90°C drying cabinet

[0044] The respective test specimen sizes correspond to the specifications of DIN 4049. The determination of the flexural strength [MPa] and the Young's modulus [MPa] was carried out according to DIN 4049.

Claims

[1] A method for producing a three-dimensional dental material block from a dental, polymerizable material, wherein the material block is suitable for producing dental prosthetic parts in a material-removing process, comprising the steps a) optional: adjusting the viscosity, b) Transferring the polymerizable dental material into a radiolucent three-dimensional casting or pressing mold, c) Planarizing at least one surface of the dental material in the three-dimensional casting or pressing mold to form a defined three-dimensional geometry of the material, wherein the planarization is carried out by applying a transparent film or a planar transparent disc to the material to be polymerized in a three-dimensional casting or pressing mold that is open on one side, and the film or disc is then subjected to pressure with a stamp to planarize the surface, and / or d) applying pressure to the polymerisable material in the three-dimensional casting or pressing mould by subjecting the polymerisable material to a pressure of 1.5 to 5 bar, e) irradiating the polymerizable dental material essentially from all sides with light in the UV / Nis range, forming polymerized outer surfaces of the dental material in the form of a solid outer shell of the dental material, wherein the shell is present in the defined three-dimensional geometry of the material, while the inner region of the material is not polymerized or partially polymerized, f) optionally removing the dental material with a dimensionally stable shell with a defined three-dimensional geometry from the casting or pressing mold, g) heating the material with a solid shell having a defined three-dimensional geometry to 60 °C to 150 °C for at least 90 minutes, h) optional: cooling of the fully polymerized material, i) Obtaining a dental, polymerized material block with defined three-dimensional geometry. [2] Method according to claim 1, characterized by, that I) the polymerisable dental material is irradiated essentially from all sides with light in the UVNis range for a period of time of between 4 minutes and 4 hours, in particular between 5 minutes and 5 minutes, and / or II) the casing in step e) has a thickness of greater than or equal to 2 to 15 mm, preferably greater than or equal to 2 to 10 mm, particularly preferably 3 to 6 mm, further preferably 3 to 4 mm. [3] Method according to claim 1 or 2, characterized by that the irradiation of the polymerizable dental material takes place as dual irradiation with intensity maxima of the light from the radiation source in the UV and in the Vis range, in particular irradiation takes place with intensity maxima of the radiation source from 350 nm to 390 nm and from 420 to 500 nm, preferably with intensity maxima around 380 nm and 450 nm. [4] Method according to one of claims 1 to 3, characterized bythat the polymerizable dental material is transferred into a radiation-permeable, three-dimensional casting or pressing mold with a hollow mold, wherein the hollow mold has the shape of a cuboid in which two surfaces are larger than or equal to DIN A5 (21 cm x 14.8 cm), in particular larger than or equal to DIN A4 (21 cm x 29.7 cm), and the remaining edge lengths are at least 20 mm. [5] Method according to one of claims 1 to 4, characterized by that in step g) the material with a solid shell, which has a defined three-dimensional geometry, is heated to 70 °C for at least 90 minutes. [6] Method according to one of claims 1 to 3, characterized by that the polymerized material block with defined three-dimensional geometry a) has at least one first edge length or a diameter of greater than or equal to 90 mm and at least one second edge length of greater than or equal to 20 mm, or b) is in the form of a cuboid with two faces larger than or equal to DIN A5, in particular larger than or equal to DIN A4, and the remaining edge length being at least 20 mm. [7] Method according to one of claims 1 to 6, characterized by that the three-dimensional casting or pressing mold is made of polymethyl methacrylate. [8] Method according to one of claims 1 to 7, characterized by that the resulting dental, polymerized material block with a defined three-dimensional geometry is divided into more than or equal to 50 milling blocks which have at least one edge length of more than or equal to 10 mm. [9] Dental material block obtainable by a method according to one of claims 1 to 7, wherein the material block has no cavities, cracks or voids which have an extension of greater than or equal to 0.05 mm in one dimension, wherein the material block has at least a first edge length or a diameter of greater than or equal to 90 mm and at least a second edge length of greater than or equal to 20 mm. [10] Use of a three-dimensional casting or pressing mould in a method according to one of claims 1 to 8 in the form of a hollow mould made of polymethyl methacrylate or polycarbonate for producing a dental material block cured by means of radiation, in particular by means of UV / Vis radiation, and at an elevated temperature. [11] Use of a polymerized material block obtainable according to one of claims 1 to 7 or according to claim 8, which has at least one edge length or a diameter of greater than or equal to 90 mm and at least a second edge length of greater than or equal to 20 mm for producing at least two smaller material blocks, in particular by dividing the material block at least once.

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