MXPA00009093A - Dental crowns and/or dental bridges - Google Patents

Abstract

The invention relates to a method and a blank for producing artificial dental crowns (28) and/or dental bridges (38) which can fit on at least one prepared stump (10). The three-dimensional outer and inner surfaces (20, 22) of a positive model (46) of the base frame (14) for the dental crowns (28) and/or for the dental bridges (38) are scanned and digitized. The determined data is linearly expanded around a factor (f), said factor exactly compensating the sinter shrinkage, in all spatial directions. The data is also transmitted to the control electronics of at least one processing machine for processing the blank (48) made of porous ceramic, and the appropriate tool paths are derived therefrom. Material which is temporally decoupled from the digitization is removed from the blank (48) by means of control commands for the tools. Said material is removed until an enlarged finished form of the positive model (46, 47) is produced. This enlarged base frame is tightly sintered to the base frame (14) with direct final measures. Finally, the base frame (14) is individualized by enameling with a coating material (24) made of porcelain or plastic. An information code which is provided for the enlargement factor (f) and which can be detected by a mechanical or human sense organ is placed on the ceramic blank, the packaging thereof, a label or on an instruction leaflet.

Description

DENTAL CROWNS AND / OR DENTAL BRIDGES The invention relates to a process for the production of an artificial dental substitute that can be adjusted in at least one pre-prepared dental strut according to the preamble of claim 1. The invention also relates to a product blank porous ceramic for the realization of the process. Numerous methods are known for the production of synthetic crowns and / or dental bridges. In principle, after the dental preparation, a tooth mold or tooth roots, the dental environment and the jaw are produced. Manually by casting with plaster, a positive model of the situation of the mouth can be produced in which a skeletal structure of wax or plastic is professionally molded. When conventional techniques are used, with known processes such as the process to the loss wax, milling with copying 1: 1 or grinding, a model of the skeletal structure and metal can be produced when baking with porcelain. Also, due to the high risk of rejection in porcelain baking, aesthetic arrangements should be made, particularly in the cervical margin, and X-ray-based diagnostic procedures for crown tooth monitoring can no longer be used. . The so-called dental ceramic porcelains used in other processes, due to their poor mechanical properties, although suitable for dental crowns with low load, are not suitable for dental bridges. EP-B1 0389461 describes a process for the production of an artificial, artificial crown for setting to fit in a prepared dental cavity. The process is based on a mold or negative form of the situation in the patient's mouth. The setting dental crowns are milled by copying, enlarged, from a raw, ceramic, raw or pre-sintered material, and then sintered in dense. The dental crown according to EP-B1 0389461 is in principle a different product of a dental crown and dental bridge since the dental indication is different. The dental crowns are placed in dental cavities and are always formed convex with respect to the geometric shape. The dental crowns, also with bridges, fit into a dental tooth and have the shape of a lid. This gives defective, fine margins that are technologically difficult to work with. An essential feature of copying milling in accordance with EP-B1 0389461 is the contemporaneousness of scanning and transferring the scanning movement to a machining tool. Essentially this corresponds to the working method of a pantograph that has been used for a long time for amplifications of line drawings. The application area of EP-B1 0389461 is therefore restricted to dental substitute products, which are formed in a convex manner exclusively, such as, for example, incrustations, tooth crowns and coatings. EP-A2 580565 describes the artificial restoration of teeth with metallurgical powder production processes of a skeletal structure of high strength, dense, ceramic that is coated with dental porcelain. The shape of the dental preparation is recorded optically or mechanically in the mouth or in a dental mold. The cavities, that is, the inner surface, and their local relationship to each other, are produced, enlarged, from another material, for example plastic, using a computer controlled milling machine. The cavities of the skeletal structure are produced in a metallurgical powder process with this shape, that is, when pressing the powder on an enlarged, pre-produced dental tooth. The outer surface of the skeletal structure is also structured by pressing. The process for the production of the skeletal structure thus differs in principle from the production of a blank by removal of material. Finally, EP 0160797 describes a blank for the production of technical molded parts, dental. The body of the molded part to be machined has a closed tolerance section that can be formed as an annex. This annex, with reference surfaces or stops, serves as a support for the insertion of the blank in a clamp for machining by removal of material. The reference surfaces may contain information encoded, explorable by the machine tool, of the properties of the blank. The inventors have faced the task of creating a process of the type initially specified, which allows the production of dental crowns and / or completely ceramic dental bridges with a skeletal structure of a high strength ceramic product, sintered in dense for adjustment and fixation with adhesive and / or retentive of natural or artificial dental ragons. The process allows the production of crowns and / or dental bridges with an occlusion and cavitation surface of materials that shrink in the sintering, which have a perfect fit even with a filigree shape, that is, they do not require additional work. In addition, a blank of ceramic oxide material is provided which allows a precise, simple embodiment of the process. The task in relation to the process is solved according to the invention by the features of claim 1. Special and additional design forms of the process according to the invention are the subject matter of the dependent claims. Starting from a dental preparation of the tooth root, a mold is made that gives a negative model of the situation in the mouth of the patient, in particular the surface of the tooth root, the approximate surfaces of the adjacent tooth and the counter-bite. Before this molding, a positive mold is produced, usually of plaster. In the positive mold of the situation a separating lacquer is applied which takes into account a separation between the surface of the skeletal structure produced on the basis of the model and the tooth root. Then in the positive mold of the situation in the patient's mouth a model for the skeletal structure of wax or plastic can be produced. This method is known and used in technical dental practice for the production of skeletal, metallic structures for dental crowns and / or bridges. The process according to the invention follows this preliminary stage, known and completely digitizes the outer and inner surface of the model of the skeletal structure or the surface in the positive model. A positive model that incompletely reflects the situation in the mouth of the patient is preferably complemented with respect to the outer and inner three-dimensional surface by computer technology, which is important in particular in the area of bridge elements of the dental bridges. The result of digitalization and any computer technology complement is a digital description of the entire surface of the skeletal structure. Digitalisation can take place mechanically or optically. The processes for digitalization in the mouth of a patient in a prepared dental strut or model are known, for example, from US A-418312 (mechanical) and EP, Bl 0054785 (optical). The essential disadvantage of the known mechanical digitalization is in the fixation of the mechanical scanning device to the patient, the safe handling of the device in the narrow cavity of the mouth is problematic. With optical digi zation devices, it is necessary to coat the tooth root with dust due to its translucent properties in order to prevent inaccuracies due to the partial and uncontrolled penetration of the light in the dental tooth that is to be measured. However, the application of a powder coating simultaneously increases the inaccuracy by the application of an almost non-uniform depth of powder in the tooth root. In the process according to the invention, the skeletal structure model is fastened with holding pins. The model of the attached skeletal structure is properly rotated in stages. A rotation of 180 ° allows a complete digitization of the occlusive and cavitally accessible surfaces of the skeletal structure model. The optimal working positions are determined in advance and controlled when the shaft is rotated. The surface dimensions of the skeletal structure model are enlarged linearly in all directions to compensate for shrinkage in sinteption. The enlargement factor f is derived from the relative density pR of the pre-produced blank and the achievable relative density ps after the interposition according to equation 1 The control orders for the machine with which the enlarged skeletal structure is completely produced and enlarged from the blank are generated from the data of the enlarged surface. Compared with the enlarged surface of the skeletal structure model, no machining allowance is required so that the subsequent shrinkage in the sintering of the precise final dimensions is achieved directly, thus retouching in the sintered state is avoided. in dense. Temporarily uncoupled from digitalization, a blank of porous ceramic material can now be formed by removal of material for the enlarged skeletal structure. For this, the blank can be fastened, for example, between two axes of a processing machine. The rotably mounted blank is machined by a suitable route, derived from a tool. The processing can take place mechanically, for example by means of the processes of production of milling or grinding with one or more tools, and / or optically with one or more beams, for example by laser beam. The machining can take place in one or more processing stages, for example, a rough machining first and then the final machining of the surfaces accessible by the tool. To change from the machined occlusive to the cavital, a change of position of the partially machined blank may be required. The axes that keep the piece blank can be rotated by the control programmed in steps and / or continuously, with a total of half a turn, a complete turn or several turns, including inverted turns. The material is preferably removed in a blank using milling tools with geometrically determined cuts at rotational speeds in the range of preferably 10,000 to 50,000 rpm, preferably an advance of > 0.5 mm, in particular 1-15 mm, and a feed rate of preferably > 3 cm / sec, in particular 3.5 - 10 cm / sec. The production of the skeletal structure, enlarged in relation to the positive model, the material of the blank is terminated by distal or median separation of the skeletal structure of the rest of the blank. At the points of separation, a slight manual retouching known as polishing may be required. The skeleton structure, enlarged, machined, finished is sintered in dense. Depending on the material used and the morphology of the powder, the temperatures normally vary in the range of 11,000 to 16,000 ° C. so that a density of 90 to 100% of the theoretically possible density can be achieved, preferably a density of 96 to 100% of the theoretically possible density, in particular more than 99% of the theoretically attainable density. During sintering, the synthetic structure shrinks linearly without additional deformation or distortion. This allows baking by sintering without also shrinking the sintering stub. The shrinkage S is calculated according to equation (1) from the relative density of the blank pR before sintering and the relative density attainable pR after sintering: After sintering, the shrunken ceramic skeletal structure is applied a porcelain or plastic coating in a conventional baking process at temperatures of 700 to 1100 ° C. One or more layers of porcelain or plastic can be applied. In this way, the dental crown or dental bridge is given an individual appearance. The dental crown or dental bridge is then attached to the tooth root prepared by cement where conventional preparation and cement fixing materials are used. The advantages of the process according to the invention can be summarized as follows: crowns and / or dental bridges, completely ceramic, sintered in dense, high quality and accurately dimensioned, can be produced in a low cost, simple and safe process. The homogenous or essential blanks for the safe and simple production process, - the dental crowns and / or dental bridges individualized to fit the prepared dental strips resist the high loads in the lateral area of the tooth and also meet the aesthetic requirements of the patient in the front area of the tooth. Particularly in the case of dental bridges, the purpose is high separation, that is, with a graceful shape between the elements of the bridge, a structure at least comparable to ceramic, metallic dental bridges, which is required by dentists for aesthetic, hygienic and phonetic reasons. With respect to the blank of porous ceramic material, the task is solved according to the invention since in the blank itself or its packaging, an attached label or a sheet of packaging instructions, a code of readable identification by machine or with human sensory organs, which contains data for the individual input of the factor of enlargement f of compensation. The porous blanks of ceramic material for the production of the skeletal structures for crowns and / or dental bridges can be made of various metal compositions, in particular from at least one metal oxide powder of the group consisting of A1203, Ti02 , MgO, Y2O3 and Zircon oxide mixed glass Zr1.xMex02- (-2) x where Me is a metal present in the form of oxide with a valence cation 2, 3 or 4 (n = 2, 3, 4 and 0) <; x < 1) and stabilizes the tetragonal and / or cubic zircon oxide phase. Additional details of the material composition of the blanks arise from dependent process claims 11 to 13. The blanks may also undergo thermal pre-treatment which is explained in more detail in dependent process claims 6 to 12. In each of the process steps for the production of a blank, the tolerances are applied, for example, in the temperature profile and the temperature fluctuations during the thermal pre-treatment of a blank. The enlargement factor f (equation 1) for the production of the skeletal structure of blanks is usually not a constant for the given reasons. Even if the blanks are made from one or the same material and are produced in the same production equipment with the same process, the magnification factor f is not constant. According to the invention, flexibility in the material and production tolerances can be achieved since the individual enlargement factor f for each blank is determined and distributed together with each blank. This is preferably achieved since the data for the enlargement factor f is applied to a blank itself, optically detectable, electromechanically or mechanically tactile, its packaging, an attached label or a sheet of packaging instructions. According to the simplest variant, the data for the manufacture of crowns and / or dental bridges can be read by the eye and can be made directly, or by means of an auxiliary program for the production of an enlarged design form of a positive model for a skeletal structure. Preferably, however, an identification system, known per se, is used, with which the data for the magnification factor f can be read and automatically converted into control commands for the tools.

Design Examples A skeletal structure is prepared for a dental bridge for adaptation to a dental preparation, from stabilized Zr02 powder containing 5.1% by weight of Y203 and slight impurities, giving a total of 0.05% by weight, of Al203, Si02, Fe203 and Na20. The main particle size is in sub-microns around 0.3 μm. The blanks are pressed isostatically around 300 MPa and in the raw state, the outer material layer less than 2 mm thick is removed by milling. After pre-processing, the diameter is 22 mm and the height is 47 mm. The density is determined as 3.185 g / cm3. The machined blank is pre-sintered for approximately 120 minutes at about 850 ° C. After the burning of the bonding agents, the relative density is 3089 g / cm 3 determined after pre-sintering. A mold of the situation in the mouth of a patient is produced with silicon mass, in particular a negative mold of the tooth root prepared with the preparation edge and approximate surfaces of the adjacent tooth is produced. A positive shape is produced when molding a mass of plaster. To create a separation of cement, the two prepared dental strips are uniformly coated on the surface with separating lacquer and the forming surface structured in this way. The skeletal structure of wax is positively molded in this positive form of the situation in the patient's mouth. The wax model of the skeletal structure is held between two axes and then in a serpentine form the occlusively accessible surface is mechanically scanned first and then, after rotation of the wax model by 180 °, the cavitally accessible surface. The result is a digital description of the entire surface of the skeletal structure. The digital description is linearly extended by the enlargement factor f 1.2512 calculated in formula (1) and from this the control orders for the processing machine are generated, taking into account the processing tools used for machining in rough and end of the skeletal structure, orders that are then transferred to the processing machine. The final milling tools with rough surface have a diameter of 13 mm for machining in rough and 1.5 mm diameter for machining in fine. The partially machined blank gripped between two axes is rotated about 180 ° so that the surface of the skeletal structure can be produced in a complete and enlarged manner from the blank. Then, the skeletal structure is separated from the remaining blank, the points of separation in the skeletal structure are smoothed by milling, and the skeletal structure is carefully cleaned of the dust residue. The enlarged skeletal structure of Zr02 with Y203 is then sintered around 1500 ° C.

After sintering, a relative density of 6.050 g / cm3 is reached, which corresponds to practically 100% of the maximum attainable density. The skeletal structure shrunk by 20.07% in the sintering can be adjusted to the positive model of the situation in the patient's mouth without additional retouching. The skeletal structure is then individualized by baking in porcelain layers at temperatures between 700 and 1100 ° C and then fixed with adhesive in the patient's mouth with phosphate cement. Using the design examples shown in the drawings that are the subject of the dependent patent claims, the invention is explained in more detail.

Schematically these show: Figure 1 a longitudinal section through a dental strut, natural with a dental crown, artificial, Figure 2 an enlarged detail of area A, according to Figure 1, Figure 3 a longitudinal section through of two dental strips with a three-part dental bridge, Figure 4 an occlusive view of the skeletal structure of a dental bridge, Figure 5 a cavital view of the skeletal structure of a dental bridge, Figure 6 the fixation situation of a model of skeletal structure for digitalization, Figure 7 the clamping situation for a blank not machined, Figure 8 the clamping situation before separation of a blank produced, and Figure 9 the clamping situation for digitizing a skeletal structure model of a dental crown. A dental strut 10 shown in Figure 1 has the pulp 12 for a nerve, not shown. This tooth root is natural and vital, in other forms of design, the dental root 10 can be structured naturally and not vitally and artificially in an implant. The tooth root 10 does not have a solomy. A skeletal structure 14 of dense sintered ceramic material is fixed in cement 10 with cement. This skeletal structure 14 has in the direction of a varnish 18 a defective, thin margin 16 which is essentially more difficult to produce and to decorate with filigree than a known dental crown of laying with exclusively convex surfaces. The outer surface 20 of the skeletal structure 14 runs convexly and can be worked in an occlusive manner, which corresponds greatly to the state of the art. The concave inner surface 22 of the skeletal structure 14 is machined in a cavital manner which, in particular in view of the defective, thin margin 16, is extremely difficult. With the present invention this problem can be solved by the use of completely ceramic material. To form a dental, artificial crown, a coating material 24 is applied in the skeletal structure 14 until the original, natural shape of the tooth is reproduced. The skeletal structure 14 is individzed with coating material 20, that is, faced with plastic porcelain material. In the enlarged area A, according to Figure 2, it is clear that additional layers are formed on both sides of the skeletal structure 14 of dense sintered ceramic material. In the direction of the dentin 11 is a cement layer 26 for adhesive fixation of the skeletal structure 14 to the dental spike 10. The coating material 24 is shown as only a relatively thin layer, it can be essentially thicker and structured with the formation of the interior surfaces 42 and thus form a dental crown 28. The surface 30 of the natural tooth root 10 is formed by dental preparation. The surface 30 runs to the preparation edge 32 in which is the fine, defective margin 16 of the skeletal structure 14. A dental strut 10 depicted on the left in Figure 3 corresponds greatly to that of Figure 1. A dental strut 10 not vital depicted on the right in Figure 3 has a lower residue of dentin 11 in which an artificial tooth root 34 anchored by a tang 36 in the dead pulp 12 is placed. In both dental strips 10, a three-part dental bridge 38 is adhesively fixed with a layer of cement 26 (Figure 2). This dental bridge 38 comprises two dental crowns 28 and a bridge element 40 which serves as a substitute for the substance of the lost tooth. Another skeletal structure 14 of three parts of high strength dense sintered ceramic material is individzed when faced with porcelain or plastic coating material 24. This coating material has an outer surface 42 which corresponds as much as possible to that of the natural, original tooth 10. According to a design form not shown, a dental bridge 38 may have more than two dental support strips 10 and / or several support elements 40. As already indicated, the dental support strips 10 can also be implants with artificial dental stringers. In the occlusive view in Figure 4, there is shown a skeletal structure 14 of three parts, with convex surface 20, exterior, in Figure 5 a cavital view of this skeletal structure 14 of a dental bridge with the inner concave surface 22.

Figure 6 shows two axes 44 driven synchronously, co-axially tapering at the end in a holding peg 45. Fastened thereon is a model 46 of skeletal structure of three parts of a dental bridge 38 (Figure 3 ) in occlusal view. The shafts 44 with the terminal holding pins 45 can be moved axially and can be rotated synchronously about a pre-set angle. After the digitalisation of the occlusive side of model 46 of the skeletal structure, the axes 44 are rotated around 180 ° and the cavital side is also digitalized. Figure 7 shows a blank 48 of the pressed ceramic powder, rotatably held between two axes 44. Directly on the blank 48 a machine-readable information code C is applied with data for the enlargement factor f, in FIG. the present case an electronically or optically readable barcode. The information code C serves, for example, as identification. For the production of the blank 48, the powder or colloid is processed into raw blanks by means of known methods of ceramic formation. Known processes for the production of ceramic raw bodies are described, for example, in WO 94/02429 and 94/24064. For reasons of production technology, geometrically simple structures such as cylinders or cubes are preferred for the blanks. Prior to the preliminary processing, the blank 48 can be subjected to a heat treatment. This is preferably carried out at temperatures in the range from 50 to 200 ° C, in particular from 90 to 150 ° C, for a duration of preferably 2 to 20 hours, in particular from 2 to 6 hours. Immediately after, the blank 48 can be further processed with removal of material to give the enlarged, skeletal structure 14. The outer layer 50 in particular is removed if the blank 48 is produced by pressing, molding or forming processes. injection, in order to remove any of the density gradients existing in the cover of an external material. The additional, conventional production processes for the blanks 48 are cold isostatic pressing, uniaxial pressing, slip casting, die casting, injection molding, extrusion, rolling and DCC (direct condensate molding). Prior to further processing in the enlarged skeletal structure 14, the blank 48 can undergo pre-sintering which is preferably carried out between 0.5 and 6 hours at a temperature of at least 450 ° C, in particular at a temperature range of 600 to 1200 ° C. The blanks in practice are usually made of a metal oxide powder from the group consisting of A1203, Ti02, MgO, Y203 and a mixed zircon oxide crystal Zr1_xMex02 - (-2) x where Me is a metal that is present in the oxide form as a bi-di- or tetravalent cation and stabilizes the tetragonal and / or cubic phase of the zircon oxide. A formula for which zircon oxide is mixed n = 2, 3 or 4 and 0 = x = l. In a specially designed form, the metal oxide powder is mixed with an organic binding agent, preferably from at least one of the class of polyvinyl alcohol alcohols (PVA), polyacrylic acids (PAA), celluloses, pol iet ilengl icoles and / or thermoplastics. Suitably, the proportion of the binding agent is in the range of 0.1 to 45% volume, preferably in the range of 0.1 to 5% by volume. Figure 8 shows in an occlusive view, the fixation situation after processing, but before the separation of the enlarged skeletal structure 14 from the remaining residue 52 of the blank 48. Figure 9 shows in cavital view the situation of digital paral ation of a model 47 of skeletal structure for a dental crown.

Claims (15)

1. Process for the production of an artificial edentulous substitute of pressed fine ceramic powder that can be adjusted in at least one prepared tooth root, where taking into account the shrinkage, the interior surface of a completely ceramic skeletal structure of biologically compatible material is calculated, where the geometric conditions in the patient's mouth are scanned and digitized, the linear enlarged data in all directions by an enlargement factor (f) that compensates in a precise way the sintering shrinkage, are transferred to the electronic control components of at least a processing machine and suitable tool paths are derived from this, the enlarged design shape of the sintered skeleton structure dense to the direct final dimensions and then individualized upon coating with a porcelain or plastic coating material characterized in that based on the scan and digit ali ation of a positive model of the situation in the mouth of the patient, taking into account the sintering shrinkage, an enlarged design form of the skeletal structure with an inner and outer surface is produced by the removal of material from a rough piece , where the control commands are sent to a suitable machine tool for the production of the enlarged design form of the skeletal structure of the blank decoupled temporarily from the digitalization. The process according to claim 1, characterized in that a positive model that incompletely reflects the situation in the mouth of the patient is complemented by computer technology in relation to the outer and / or inner three-dimensional surface, particularly in the area of bridge elements of dental bridges. The process according to claim 1 or 2, characterized in that the enlargement factor of the positive model of a skeletal structure is established based on the material composition and powder properties, preferably according to the Formula f = \ where pR is the relative density of the pre-produced blank and ps is the achievable relative density after sintering. The process according to any of claims 1 to 3, characterized in that the dental crowns and / or dental bridges are formed with defective, fine margins. The process according to any of claims 1 to 4, characterized in that the enlarged, machined skeletal structure is sintered at a density ps of 90 to 100% of the theoretically possible density, and preferably a density ps of 96 at 100% of the theoretically possible density, and in particular at a ps density of more than 99% of the theoretically possible density. 6. The process according to any of claims 1 to 5, characterized in that a blank or pre-sintered blank of fine, pressed, ceramic powder is used, where the pre-sintering preferably takes place only after the pre-sintering. the removal of the outer layer of material. The process according to any of claims 1 to 6, characterized in that the blank is processed mechanically and / or optically, where a rough machining takes place first and then a final machining. The process according to any of claims 1 to 7, characterized in that the preform is subjected to a heat treatment at temperatures in the range of 50 to 200 ° C, preferably 90 to 150, before the pre-treatment. ° C, for a duration of 2 to 20 hours, preferably from 2 to 6 hours. The process according to claim 8, characterized in that the blank after the heat treatment is further processed with removal of the material in the enlarged skeletal structure. The process according to any of claims 1 to 9, characterized in that the blank, before further processing in the enlarged skeletal structure suffers pre-sensing for 0.5 to 6 hours at a temperature of at least 450 ° C, preferably in the range of 600 to 1200 ° C. The process according to any of claims 1 to 10, characterized in that a blank of at least one of the metal oxide powders of the group consisting of A1203, Ti02, MgO, Y203 and zircon oxide mixed glass Zrx_xMex02 - (-2) x where Me is a metal that is present in the oxide form as a bi-di- or tetravalent cation (n = 2, 3, 4 and 0 <; x < 1) and stabilizes the tetragonal and / or cubic zircon oxide phase. 1

2. The process according to any of claims 1 to 11, characterized in that the metal oxide powder with an organic binding agent is used, preferably from at least one of the class of polyvinyl alcohol (PVA) alcohols. , polyacrylic acids (PAA), celluloses, pol iet ilenglucoles and / or thermoplastics. The process according to claim 12, characterized in that the proportion of the binding agent is in the range of 0.1 to 45% by volume, preferably in the range of 0.1 to 5% by volume. 14. The blank of porous ceramic material for carrying out the process according to any of claims 1 to 13, characterized in that, in the blank from which the material itself is to be removed, or its packaging is applies an attached label or a packing instructions sheet, a machine readable information code with human sensory organs, with data for the individual input of compensation enlargement factor. 15. The blank according to claim 14, characterized in that the applied identification code can be detected optically, electromechanically or mechanically-tactile. SUMMARY OF THE INVENTION The invention relates to a method and a blank for producing dental crowns (28) and / or artificial bridges (38) that can be adjusted in at least one prepared stub (10). The three-dimensional exterior and interior surfaces (20, 22) of the positive model (46) of the base frame (14) for the dental crowns (28) and / or for the dental bridges (38) are scanned and digitized. The determined data expands in a linear way around a factor (f), this factor that compensates in an exact way the shrinkage in the sintering, in all the spatial directions. The data is also transmitted to the electronic control components of at least one processing machine for the processing of the blank 48 made of porous ceramic material, and appropriate routes for the tools are derived from it. The material that is temporarily decoupled from the digitalisation is removed from the blank by means of control commands for the tools. This material is removed until a finished, enlarged form of the positive model is produced (46, 47). This enlarged base frame is hermetically sintered to the base frame (14) with direct final measurements. Finally, the base frame (14) is individualized by varnish with a coating layer (24) made of porcelain or plastic. An information code that is provided for the enlargement factor (f) and that can be detected by a human or mechanical sensory organ is placed in the ceramic blank, the packaging thereof, or the label or instruction sheet .