Method and device for shortening denture teeth for dental prostheses

Abstract

Method for shortening prefabricated denture teeth for dental prostheses in the form of partial or complete dentures, wherein the method is characterized by the following steps: A) Creating or providing a virtual 3D model of a dental prosthesis with a virtual model of a prosthesis base (1) as a gingival imitation and with at least one virtual model of at least one machined prosthesis tooth (4) to be arranged in the prosthesis base (1) to replicate at least one tooth; B) Calculating a cervical volume (9) to be cut off from at least one prefabricated denture tooth (4) with known geometry by comparing the at least one virtual model of the at least one machined denture tooth (4) with at least one virtual model of the at least one prefabricated denture tooth (4) using a CAD method, wherein the cervical volume (9) to be cut off is located on a cervical side (8) of the at least one prefabricated denture tooth (4); C) Calculating at least one cutting surface for separating the cervical volume (9) to be cut off calculated in step B) from the at least one prefabricated denture tooth (4), wherein the at least one cutting surface includes an interface between the cervical volume (9) to be cut off from the at least one prefabricated denture tooth (4) and the respective remaining denture tooth (4); D) Fixing at least one prefabricated denture tooth (4) with a holder (12, 30), wherein the prefabricated denture tooth (4) consists of at least 90 wt% of a plastic in at least a cervical area; E) Removal of the cervical volume (9) to be cut off calculated in step B) from the at least one fixed prefabricated prosthetic tooth (4) by at least one cut with a laser beam (24), wherein the laser beam (24) is guided relative to the at least one fixed prosthetic tooth (4) and / or the prosthetic tooth (4) in the holder (12, 30) is guided relative to the laser beam (24) according to the at least one calculated cutting surface in step C).

Description

[0001] The invention relates to a method for shortening prefabricated denture teeth for dental prostheses. The dental prostheses are manufactured using the shortened denture teeth, and the dentures are produced in the form of partial or complete dentures. The invention also relates to a method for manufacturing dental prostheses in the form of partial or complete dentures, wherein the dentures comprise several denture teeth and a denture base imitating gingiva for placement on the gingiva, and wherein the denture teeth are fixed in the denture base. The invention further relates to a device for implementing such a method.

[0002] Alongside traditional craftsmanship, digital manufacturing methods are gaining increasing importance in dentistry. For several years now, dental prostheses and other dental components, such as crowns, bridges, and three-dimensional models of a patient's oral cavity, have been manufactured subtractively using CAD / CAM technologies via milling processes (CAM - Computer-Aided Manufacturing, CAD - Computer-Aided Design). CAD / CAM methods are also increasingly used in the fabrication and design of partial and complete dentures with a denture base that rests on the gingiva and supports or incorporates denture teeth.

[0003] Furthermore, generative CAM processes such as stereolithography and DLP (Digital Light Processing) are becoming increasingly important for polymer-based dental products such as temporary restorations, prostheses, orthodontic appliances, bite splints, drilling templates or dental models.

[0004] In the context of digital design of prosthetic work, especially partial or complete dentures, the construction is divided into a "white" tooth component (the denture teeth) and a colored denture base component (the denture base).

[0005] There are methods, such as those known from DE 10 2009 056 752 A1 or WO 2013 / 124 452 A1, in which a partial or complete dental prosthesis is digitally set up and produced using CAD / CAM processes. US 2018 / 0098829 A1 discloses a method for digitally modeling prosthetic teeth. Patent DE 103 04 757 B4 discloses a method for manufacturing dental prostheses in which the teeth are virtually set up in a virtual model and a prosthesis base is manufactured based on this virtual model. EP 2 742 906 A1 discloses a method in which a dental arch is connected to an impression material, the impression material being contained in a customized impression tray and containing an impression of the patient's oral cavity.The surface of the form with the dental arch is digitized, and then a virtual model of the dental arch is computationally positioned and oriented as appropriately as possible in the virtual model of the denture base.

[0006] DE 10 2017 108 592 B4 discloses a method for manufacturing denture teeth with parallel roots for inserting groups of denture teeth into a denture base with matching parallel tooth sockets. DE 10 2018 101 663 A1 describes a method for manufacturing a dental prosthesis in which a wax base for a wax prosthesis and the denture teeth inserted therein are subtractively machined basally, whereby the denture teeth are shortened more than the underside of the wax denture base.

[0007] WO 2016 / 091 762 A1 discloses a method for manufacturing a dental prosthesis in which a template is produced with which several prosthesis teeth can be attached to a denture base in the desired position and orientation relative to each other. The prosthesis teeth are shortened by basal grinding in a cervical area to achieve the desired occlusal height. WO 2016 / 110 392 A1 discloses a method for manufacturing a dental prosthesis in which a plastically deformable connecting element is inserted into tooth sockets of a denture base to allow manual correction of the alignment of the prosthesis teeth in the denture base. DE 102 16 590 A1 discloses a method for manufacturing prosthesis teeth from a ceramic by vaporizing or dissolving the ceramic with an ultrashort pulse laser.German patent DE 10 2008 019 694 B3 discloses a method and equipment for manufacturing ceramic dental components using a laser. The system is not suitable for processing plastic teeth. Dental components are produced by laser ablation from a solid ceramic body, with optical monitoring during the manufacturing process. The dental components are manufactured with an oversize to allow for subsequent surface finishing that is unattainable with the laser alone. This necessitates post-processing in the form of precision machining and smoothing. The method utilizes a high-power fiber laser exceeding 500 W, requiring safety devices. The scanner optics required for controlling the cutting path make the method and equipment expensive. Otherwise, clean ablation cannot be achieved with the system's vertical focus.

[0008] For the production of denture teeth, it is possible to manufacture the necessary geometries individually, for example by milling or printing. In most cases, however, prefabricated components, such as prefabricated artificial denture teeth, are preferred. These offer fundamental advantages due to their excellent aesthetics, good material properties, and high manufacturing precision achieved through industrial processes.

[0009] Prefabricated denture teeth or denture tooth segments are available in a wide variety; however, not every application can be realized without modifying the product. In many cases, the prefabricated denture teeth need to be shortened in the cervical area or their thickness adjusted so that they remain within the defined external geometries of the future prosthesis and integrate well both functionally and aesthetically.

[0010] Several methods are known for the necessary processing. For example, prosthetic teeth positioned within a wax frame can be shortened. Alternatively, the prefabricated prosthetic teeth can be manually modified, although this requires the use of a pre-made fixing key. Other known methods involve subsequently shortening the inserted teeth and removing the excess material.

[0011] WO 2016 / 169 921 A1 discloses a device and a method for holding denture teeth, enabling cervical (basal) machining of prefabricated denture teeth. Another method for holding denture teeth for the purpose of cervical machining is known from WO 2017 / 093 432 A1. WO 2017 / 005 905 A1 proposes machining a set of denture teeth fixed in shrink film. The shrink film must be removed with the CAM device in the areas where the denture teeth are to be machined. US 2019 / 0 167 394 A1 discloses a template in which the denture teeth to be machined basally are covered in the areas that are not to be machined and thus shortened. The exposed areas of the basal ends of the denture teeth can be easily milled down manually using the template.

[0012] In the production of removable dentures, such as complete and partial dentures, which are manufactured using digital data and CAD design, there are technical solutions for separating the data of the denture base and the teeth. The denture base can be produced using either additive or subtractive manufacturing processes. Prefabricated denture teeth made of plastic, such as polymethyl methacrylate (PMMA), or individually manufactured denture teeth or dental arches made from the same materials are suitable options. In any case, the denture base must have sockets to accommodate these denture teeth, into which the denture teeth or dental arches are then attached in a subsequent manual manufacturing step, for example, by bonding.

[0013] For the process of digital full denture or partial denture manufacturing, it is necessary to shorten the prefabricated denture teeth cervically (basally) in order to adapt the tooth height of the denture teeth to the patient's jaw or to the patient's oral cavity situation.

[0014] Methods for this are known from EP 2 571 451 B1 and EP 2 666 438 A2, in which prefabricated denture teeth are embedded in wax in a holder and then milled cervically using a CAM process. The shortened denture teeth are then removed from the wax and inserted into a denture base and bonded in place to fabricate a dental prosthesis. A disadvantage of this method is that parts of the wax must be milled away along with the portions of the denture teeth being removed. It is necessary to shorten the denture teeth cervically to adapt the tooth height to the patient's jaw, i.e., to adjust the bite height of the dental prosthesis to the patient's needs. Furthermore, CAM milling machines are expensive and complex to operate and are not available in every dental laboratory.

[0015] All these methods have in common that they involve mechanical processing, which requires very stable fixation to achieve sufficient precision. This can be achieved by clamping in a holder system or by casting in a holding medium, such as wax. A disadvantage of processing the generally small denture teeth and denture tooth segments is that, due to the necessary accessibility of the cervical areas to be shortened, there are hardly any secure fixation surfaces available.

[0016] The object of the invention is to overcome the disadvantages of the prior art. In particular, it aims to provide a method and a device for precisely machining the cervical surface of prefabricated denture teeth in a way that is as easy, quick, and cost-effective as possible. This machining should result in minimal mechanical stress on the denture teeth, lower than that achieved with conventional milling methods. Furthermore, the machined surface should ideally have a roughness suitable for bonding the denture teeth. Finally, the invention should enable individual shaping in the cervical area, ensuring that the machined denture teeth are indexed in such a way as to define their precise position and orientation within the denture base.

[0017] The problems of the invention are solved by a method according to claim 1 and a device according to claim 12. Preferred variants are claimed by dependent claims 2 to 11 and 13 to 15.

[0018] The objects of the invention are thus solved by a method for shortening prefabricated denture teeth for dental prostheses in the form of partial or complete dentures, wherein the method is characterized by the following steps: A) Creating or providing a virtual 3D model of a dental prosthesis with a virtual model of a prosthesis base as a gum imitation and with at least one virtual model of at least one machined prosthesis tooth to be arranged in the prosthesis base to replicate at least one tooth; B) Calculating a cervical volume to be cut off from at least one prefabricated denture tooth with known geometry by comparing the at least one virtual model of the at least one machined denture tooth with at least one virtual model of the at least one prefabricated denture tooth using a CAD method, wherein the cervical volume to be cut off is located on a cervical side of the at least one prefabricated denture tooth; C) Calculating at least one cutting surface for separating the cervical volume to be cut off calculated in step B) from the at least one prefabricated denture tooth, wherein the at least one cutting surface includes an interface between the cervical volume to be cut off from the at least one prefabricated denture tooth and the respective remaining denture tooth; D) Fixing at least one prefabricated denture tooth with a holder, wherein the prefabricated denture tooth consists of at least 90% by weight of plastic in at least one cervical area; E) Removal of the cervical volume to be cut off calculated in step B) from the at least one fixed prefabricated prosthetic tooth by at least one cut with a laser beam, wherein the laser beam is guided relative to the at least one fixed prosthetic tooth and / or the prosthetic tooth in the holder is guided relative to the laser beam according to the at least one calculated cutting surface in step C).

[0019] Dental prostheses, including partial and complete dentures, are designed to replace completely lost teeth. They consist of at least one denture tooth and a denture base. The denture base is a gum imitation. A denture base can be placed on or attached to a toothless jaw. The denture tooth or teeth serve to replicate missing teeth and are intended primarily to restore the jaw's chewing function as well as its aesthetic appearance.

[0020] A denture tooth has a coronal and a cervical region. The cervical region is positioned opposite the coronal region. The coronal region comprises the biting surface (occlusal surface) of the denture tooth and the surrounding adjacent lateral areas and should preferably not be modified. The cervical region serves to anchor the denture tooth in the denture base and is located basally. For this purpose, the cervical region of a denture tooth can be inserted into a suitable socket in the denture base and connected to it.

[0021] It may be specified that the plastic is a polymethyl methacrylate plastic or a plastic made from a methacrylate copolymer.

[0022] In order to guide the laser beam relative to the at least one fixed prosthetic tooth and / or the prosthetic tooth in the holder relative to the laser beam according to the at least one calculated cross-sectional area in step C), the line formed by the laser beam is guided in such a way that the line passes completely through the at least one calculated cross-sectional area, whereby the line of the laser beam always lies in the cross-sectional area and in particular over the entire cross-sectional area.

[0023] Preferably, only one incision is made with the laser beam. However, it is also possible to reposition at least one prosthetic tooth at least once and then make another incision. Automated positioning of the prosthetic tooth can be used for this purpose.

[0024] The cutting surface may be designed to intersect the cervical axis of at least one prefabricated denture tooth, preferably being perpendicular or nearly perpendicular to the cervical axis. If the cutting surface is nearly perpendicular to the cervical axis of the at least one prefabricated denture tooth, the cutting surface should (on average) be inclined at no more than 30° to the cervical axis, preferably no more than 15°. The cervical axis extends from the coronal end to the cervical end of the denture tooth and preferably passes through the centroid of the respective denture tooth.

[0025] It is also possible for the cut surface to be wavy and / or stepped. This allows for indexing of at least one processed denture tooth on the cervical side. This ensures unambiguous positioning of the denture teeth in the denture base.

[0026] Preferably, the removal of the cervical volume to be cut off in step E) reduces the tooth height of at least one prosthetic tooth, particularly preferably by at least 1%. The tooth height corresponds to the length of the cervical axis within the volume of the prosthetic tooth.

[0027] The coronal side of at least one prosthetic tooth is preferably not cut and is especially preferably left unchanged.

[0028] It may be provided that at least one cross-sectional surface is realized by at least one cross-sectional plane.

[0029] Furthermore, it is provided that at least one of the cutting surfaces includes an interface between the cervical volume to be cut off from the at least one prefabricated prosthetic tooth and the remaining prosthetic tooth.

[0030] This allows the cervical volume to be removed in as few steps as possible.

[0031] Furthermore, it can be provided that in step B) the cervical volumes to be cut from several prefabricated denture teeth with known geometry are calculated, in step D) several prefabricated denture teeth are fixed, and in step E) the several prefabricated denture teeth are cut with the laser beam, wherein preferably the cutting surfaces in step B) are chosen such that each of the denture teeth processed in step E) receives an individual cervical shape.

[0032] This prevents confusion regarding the positions of the processed, prefabricated denture teeth when inserting them into a denture base with matching tooth sockets.

[0033] It may also be provided that at least one prefabricated prosthetic tooth consists entirely, or at least in a cervical area, of a plastic material.

[0034] This makes it possible, or at least significantly easier, to process at least one prosthetic tooth using laser cutting techniques.

[0035] It may also be stipulated that the plastic contains at least one inorganic pigment and / or at least one inorganic filler.

[0036] This can improve the optical appearance and mechanical properties of the prosthetic teeth.

[0037] The plastic preferably contains up to 5 wt%, and most preferably between 1 wt% and 5 wt% of the at least one inorganic pigment and / or the at least one inorganic filler.

[0038] This ensures that the cuts can still be made with conventional lasers, while at the same time improving the advantages in terms of the optical appearance and mechanical properties of at least one prosthetic tooth through pigments and fillers.

[0039] According to a further development of the inventive method, it can be provided that a laser head for generating the laser beam and / or an optic is moved in order to move the laser beam relative to the at least one fixed prosthetic tooth.

[0040] This allows the laser beam to be guided to create the desired cut even with a stationary laser and at least one fixed prosthetic tooth.

[0041] It may also be possible to use a CO2 laser to generate the laser beam.

[0042] Furthermore, it can be provided that the laser beam has a power of less than 1 kW, preferably a power between 4 W and 400 W, and particularly preferably a power between 20 W and 200 W.

[0043] The power here refers to the power emitted by the laser with the laser beam (beam power) and not to the power absorbed by the laser.

[0044] This allows at least one prosthetic tooth to be cut quickly and precisely, without the need for additional post-processing of the laser cut surface and without the risk of the processed prosthetic tooth cracking or breaking due to thermal stresses in the material caused by the energy input.

[0045] Alternatively, it may be provided that, in step D), the at least one prefabricated prosthetic tooth is clamped with the holder to fix it in place.

[0046] This enables a stable hold for at least one prefabricated prosthetic tooth, so that movement of at least one prefabricated prosthetic tooth against the laser beam is also possible.

[0047] The holder may be provided with a negative mold for receiving at least one prefabricated prosthetic tooth, preferably having a negative mold that fits coronal areas of the at least one prefabricated prosthetic tooth and / or the negative mold being made of an elastic material, in particular rubber or silicone.

[0048] This further simplifies the processing of the at least one prefabricated denture tooth. The elastic material must be soft enough so that the at least one prefabricated denture tooth can be manually inserted into the negative mold. The at least one prefabricated denture tooth cannot be damaged in the process.

[0049] The problems underlying the present invention are also solved by a method for manufacturing dental prostheses in the form of partial or complete dentures, the dental prostheses comprising several denture teeth and a denture base as a gingival imitation for placement on gingiva, wherein the denture teeth are fixed in the denture base, wherein the method comprises one of the previously described methods according to the invention and the method additionally comprises a step F): F) fixing the at least one denture tooth processed in step E) in at least one suitable tooth socket of a denture base, wherein preferably the at least one prefabricated denture tooth is glued into the at least one suitable tooth socket of the denture base.

[0050] This enables the complete production of a dental prosthesis.

[0051] It may be provided that no further processing of the cut surface produced with the laser beam takes place before the at least one prosthetic tooth processed in step E) is fixed in the prosthetic base.

[0052] This makes the process particularly easy, quick and cost-effective to implement.

[0053] The problems underlying the present invention are further solved by a device for implementing a method according to the invention, the device comprising a calculation module for performing the calculations of method steps B) and C), a holder for fixing at least one prefabricated prosthetic tooth in a unique position, a laser to generate a laser beam, a controllable motion device with which the laser beam of the laser is movable relative to the holder by making the holder movable against the laser and / or making the laser movable against the holder and / or making the laser beam movable against the holder by means of a movable head or movable optics, and a control system for controlling a movement sequence of the movement device, such that the laser beam of the laser is movable relative to the holder according to the calculation according to step C) of the calculation module, so that the at least one prosthetic tooth fixed in the holder in the unique position is cut on the cervical side with the laser beam according to the cutting surface.

[0054] The device may preferably include an automatic setup system for changing the prefabricated denture teeth to be trimmed.

[0055] The movement device may preferably have at least one motor, in particular at least one electric motor.

[0056] The calculation module is preferably programmed to perform the calculations of process steps B) and C).

[0057] It may be provided that the laser is a CO2 laser with a power of less than 1 kW, preferably with a power between 4 W and 400 W, particularly preferably with a power between 20 W and 200 W.

[0058] The power here refers to the power emitted by the laser with the laser beam (beam power) and not to the power absorbed by the laser.

[0059] This allows at least one prosthetic tooth to be cut quickly and precisely without the need for additional post-processing of the laser cut surface.

[0060] Furthermore, the holder may include a negative mold for receiving the at least one prefabricated denture tooth, preferably having a negative shape that fits the coronal areas of the at least one prefabricated denture tooth and / or the negative mold being made of an elastic material, in particular rubber or silicone.

[0061] This simplifies the processing of at least one prefabricated denture tooth.

[0062] It can also be provided that the laser beam of the laser is movable with the controllable motion device in such a way that a cut with a profile can be produced, in particular with a step profile and / or a wave profile.

[0063] This allows for the creation of individualized shapes that permit unambiguous positioning in a prosthetic base.

[0064] The invention is based on the surprising discovery that prefabricated denture teeth, which consist essentially of a plastic material, can be shortened with a laser beam by making cuts in a cervical area to achieve the desired bite height and occlusion of a dental prosthesis manufactured with them. For this purpose, the laser-treated denture teeth are connected to a denture base. The laser beam not only allows the cut to be made so precisely that fine-tuning is unnecessary, but it also creates a surface roughness on the cut surfaces that is particularly suitable for bonding the treated denture teeth. The laser beam can also be used to easily index the cervical areas of the denture teeth, so that each treated denture tooth fits precisely into only one tooth socket and thus into exactly one position in the denture base.Furthermore, this allows the position of the denture teeth within the denture base to be predetermined. This prevents incorrect positioning and alignment of the denture teeth.

[0065] The present invention thus enables direct precision cutting with the laser beam to the final dimension with high surface quality; material removal to the final dimension is not necessary. The method according to the invention can be used to cut prefabricated denture teeth made of PMMA-based plastics containing inorganic pigments and fillers. The present invention also makes it possible for a laser beam, acting as a cutting laser, to move over the static, prefabricated denture tooth. This advantageously allows for direct perpendicular cuts with the laser beam. Furthermore, it is particularly advantageous that the cutting path is predefined and can be implemented precisely according to a stored specification without verification or control measurements.For cutting prefabricated denture teeth with a laser beam, it may be sufficient to cut off a portion in the cervical area to achieve the desired tooth height. Furthermore, the inventive method allows for the direct use of a CO2 laser with a movable head.

[0066] It was also surprisingly found that a medium focus for the laser is sufficient to implement the inventive method and that clean cuts are possible even with thicknesses between 10 mm and 20 mm.

[0067] The invention provides a method for shortening prefabricated denture teeth, preferably prefabricated denture teeth made of PMMA and methacrylate copolymers, with high precision, without the aforementioned disadvantages. The prefabricated denture teeth can particularly preferably contain up to 5% by weight of pigments and / or inorganic fillers. With larger proportions of inorganic fillers or pigments, performing the at least one cut with the laser beam becomes more complex, for example, by requiring the use of a laser with higher power.

[0068] To implement the method according to the invention, software for defining the cutting surfaces and cutting planes with the laser beam, a laser, preferably a CO2 laser, with a power output between 20 W and 200 W, and a controllable motion device can be used. The controllable motion device can be used to position and move the at least one prosthetic tooth relative to the laser beam or vice versa. The controllable motion device serves as an alignment system and can be implemented, for example, by a robot arm or other 3-dimensionally movable fixtures.

[0069] The prosthetic teeth can be cut with high speed and a straight, uniform cut using a laser. The cut surfaces are precisely defined. No mechanical forces are generated that could alter the positioning of at least one prefabricated prosthetic tooth in its holder. The surfaces of the cut are slightly roughened after cutting, which can offer additional advantages during subsequent integration (for example, during bonding) into the denture base.

[0070] The methods and apparatus according to the present invention can be used for defined on-site shortening in the dental laboratory or, alternatively, for industrial shortening at the manufacturer of the prefabricated denture teeth, optionally coupled with a service for individual processing. For example, the laboratory could digitally transmit the required geometries to the manufacturer, who would then shorten the prefabricated denture teeth according to the specifications using a method according to the invention and provide the processed (shortened) denture teeth to the customer in the exact required shape.

[0071] Exemplary embodiments of the invention are explained below with reference to five schematically represented figures and a flowchart, without, however, limiting the invention. These figures show: Fig. 1: A schematic perspective view of a denture base or a virtual model of a denture base for a complete dental prosthesis to treat an edentulous maxilla, Fig. 2: a schematic perspective view of a set of provisional denture teeth or a virtual model of denture teeth for a complete dental prosthesis to treat an edentulous maxilla, Fig. 3: a schematic representation of an exemplary device according to the invention for implementing a method according to the invention for shortening prefabricated denture teeth, Fig. 4: A schematic top view of a holder for positioning prefabricated denture teeth, Fig. 5: a schematic cross-sectional view of the bracket according to Fig. 4 with inserted prefabricated denture teeth, the cut being perpendicular to the top view Fig. 4 runs, and Fig. 6: the process of a method according to the invention for shortening prefabricated denture teeth and for producing a dental prosthesis.

[0072] In some cases, the same reference symbols are used for similar parts and areas, even when the versions differ. This applies particularly to prosthetic teeth 4 and their components and virtual models. In all cross-sectional views, cut surfaces are shown hatched.

[0073] Fig. Figure 1 shows a schematic perspective view of a denture base 1 or a virtual model of the denture base 1. The denture base 1 can be used for support or attachment to the gingiva. The denture base 1 can be designed to mimic gingiva. The denture base 1 can be made of a pink-tinted plastic. The color and transparency can be chosen to match the appearance of gingiva. On one side of the denture base 1, a number of tooth sockets 2 can be provided for the fixation of denture teeth (in Fig. (1 not shown) is provided. The denture base 1 can have a palatal plate 3, which is framed in a U-shape by the arch that replicates the gingiva on the alveolar ridge. A denture base for a mandible would accordingly not have a palatal plate 3 and would instead have a recess for the tongue.

[0074] Fig. Figure 2 shows a perspective view of a set of denture teeth 4, or rather, a virtual model of the denture teeth 4. The virtual model of the denture teeth 4 and the denture base 1 can be obtained from a virtual model of a dental prosthesis by computationally splitting the virtual model of the dental prosthesis into the virtual model of the denture base 1 and the virtual model of the denture teeth. The denture teeth 4 can then be inserted into the denture base 1 according to... Fig. 1. The prosthetic teeth 4 may be present individually, as is the case in the Fig. 2 shown and is preferred according to the invention, so that the prosthetic teeth 4 are then individually available and not connected to each other.

[0075] In the Fig. 1 and Fig. 2. No distinction is made between the virtual models of the denture base 1 and the denture teeth 4 on the one hand, and the physical denture base 1 and the physical denture teeth 4 on the other, since both look the same in the schematic representation. Fig. 1 and Fig. Figure 2 shows both the virtual models of the denture base 1 and the denture teeth 4, as well as a physical denture base 1 that was manufactured using the virtual model of the denture base 1, and physical denture teeth 4 that were shortened using a method according to the invention based on the virtual model of the denture teeth 4.

[0076] The denture teeth 4, or the physical denture teeth 4 shortened based on the virtual model of the denture teeth 4 (the modified denture teeth 4), are preferably made of a tooth-colored plastic. The plastic may contain ceramic or inorganic fillers. Each denture tooth 4 can have a coronal surface 6 (occlusal surface) and a cervical surface 8 (basal surface). The cervical surface 8 can be bonded into the recesses formed by the tooth sockets 2 in the denture base 1 to fabricate the denture. The tooth sockets 2 can be indexed so that the modified denture teeth 4 with a matching cervical surface can only be inserted into the denture base 1 in a specific orientation, and each modified denture tooth 4 fits exactly into only one tooth socket 2.

[0077] The tooth sockets 2 can preferably fit the basal counterparts on the cervical side 8 of the processed denture teeth 4 in such a way that the processed denture teeth 4 can be inserted into the recesses formed by the tooth sockets 2 and are held there by a press fit.

[0078] The Fig. Figure 3 shows a schematic representation of an exemplary device according to the invention for implementing a method according to the invention for shortening prefabricated denture teeth 4. The prefabricated denture teeth 4 are shortened on a cervical side 8. For this purpose, a cervical volume 9 of the prefabricated denture tooth 4 can be cut off.

[0079] The device can include a calculation module 10 in which the cervical volume 9 to be cut off is calculated using virtual models. The prefabricated denture tooth 4 can be positioned using a holder 12. For this purpose, the holder 12 can include at least one pump 14, several suction tubes 16, and several suction cups 18. The prefabricated denture tooth 4 can be positioned with the holder 12 during the procedure. It is also possible for the prefabricated denture tooth 4 to be moved with the holder 12 against the rest of the device. The holder 12 can additionally include a robotic arm (not shown) with which the denture tooth 4 can be moved.

[0080] The device comprises a laser 20. The laser 20 can be a CO2 laser with an output power (radiation power) of 100 W. A head 22 for deflecting a laser beam 24 generated by the laser 20 can be arranged on the laser 20. Movable optical parts of the head 22, or the entire head 22, can be moved by a motion device 26, such as a motor, or comprising at least one motor. This allows the laser beam 24 to be moved relative to the holder 12 and the prefabricated prosthetic tooth 4 held by it. The holder 12 preferably holds the prefabricated prosthetic tooth 4 on a coronal side 6 so that the laser beam 24 does not strike the holder 12.

[0081] The motion device 26 can be controlled by a controller 28, so that the movement sequence of the laser beam 24 is controlled by the controller 28. The controller 28 is connected to the calculation module 10. This allows the controller 28 to control the movement sequence of the laser beam 24 according to the calculations performed by the calculation module 10. The position of the prefabricated prosthetic tooth 4 is determined and known by the holder 12. It is possible to additionally measure the exact position and use this information from the controller 28 to ensure precise guidance of the laser beam 24 relative to the prefabricated prosthetic tooth 4.

[0082] The control unit 28 can also be connected to the holder 12 to switch the holding function on and off and / or to move the holder 12 against the laser beam 24.

[0083] Alternatively to the one in Fig. Instead of the bracket 12 shown in the 3, a simpler bracket 30 can also be used, as shown in the Fig. 4 and Fig. Figure 5 shows the holder 30. It can be made of an elastic material such as rubber or silicone, or of another easily elastically deformable material, such as foam or similar. The elastically deformable material of the holder 30 should be dimensionally stable enough that the weight of the denture teeth 4 does not cause the holder 30 to deform to such an extent that the positions of the denture teeth 4 within the holder 30 change and thus become inaccurate. The holder 30 can have several recesses 32 for receiving denture teeth 4. The denture teeth 4 can be inserted into the recesses 32 with their coronal side 6 facing forward, whereby the walls of the recesses 32 deform elastically and then conform laterally to the denture teeth 4. This allows the denture teeth 4 to be held in the holder 30.The receptacles 32 are shorter than the height of the denture teeth 4, so that the cervical surface 8 of the denture teeth 4 protrudes and can be processed with the laser beam 24. Since no significant force is exerted on the denture teeth 24 by the laser beam 24, the denture teeth 4 remain in the desired position. Therefore, a very easily elastically deformable material, such as foam, can be used as the material for the holder 30. The location and position of the receptacles 32 in the holder 30 are known and fixed, so the location and position of the denture teeth 4 fixed therein are also known.

[0084] The denture teeth 4 in the holder 30 can therefore be precisely cut and shortened with the laser beam 24. The cervical side 8 protrudes from the holder 30 and can thus be easily processed or cut by the laser beam 24. The cervical volume 9 to be cut off on the cervical side 8 of the prefabricated denture teeth 4 can be removed with the laser beam 24. A step 34 in the form of at least a bend can be created. This step 34 can be selected differently for each of the prefabricated denture teeth 4 in order to achieve an indexing of the processed denture teeth 4, which allows for unambiguous positioning of the processed denture teeth 4 in the denture base 1.

[0085] The device may preferably include an automatic setup system (not shown) for changing the prefabricated denture teeth 4 to be trimmed.

[0086] The following is an example procedure based on the one described with Fig. Section 3 of the inventive device is explained. The sequence of the exemplary method is shown in the diagram according to Fig. Figure 6 is shown. However, the description can easily be applied to other embodiments.

[0087] In a first step, existing CAD data for the shape of a dental prosthesis can be imported. The data can be stored in a memory accessible to the calculation module 10 and, if applicable, the control unit 28. A data interface (not shown) may be provided for this purpose, allowing the CAD data to be imported into the device. The CAD model of the dental prosthesis can be generated using virtual models of prefabricated denture teeth, which are positioned in a denture base adapted to the patient's oral cavity. Such methods are known from the prior art.

[0088] In a second step, using file splitting, a CAD model of the prosthetic teeth 4 and a CAD model of the prosthetic base 1 can be created from the imported CAD data.

[0089] In a third step 102, the shape of the denture teeth 4 according to the CAD model of the dental prosthesis can be compared with the shape of the prefabricated denture teeth 4. Using calculation module 10, the cervical volume 9 to be cut off from the prefabricated denture teeth 4 can be calculated from this.

[0090] Prefabricated denture teeth available in varying degrees of reduction can also be used. This method allows the selection of denture teeth with the smallest cervical volume from a number of prefabricated denture teeth of different lengths and the same coronal shape. The known shapes of these prefabricated denture teeth can then be used to calculate the cervical volume to be removed from the prefabricated denture teeth.

[0091] After the third work step 102, a fourth work step 103 can be performed, in which a movement sequence of the laser beam 24 is calculated using the calculation module 10. A known position and orientation of the prefabricated prosthetic teeth 4, held in the holder 12, 30, is assumed. This data is subsequently used by the controller 28 to control the movement device 26.

[0092] In a fifth work step 104, the movement device 26 can be controlled with the help of the control 28 so that the laser beam 24 separates the cervical volume 9 to be cut off from the pre-made prosthetic tooth 4.

[0093] Subsequently, in a sixth step (105), the cervically shortened denture tooth 4 can be removed. The procedure can be repeated until all denture teeth 4 have been shortened. The procedure can also be performed recursively. For example, after the sixth step (105), the procedure can be continued with the third step (102) or with the fifth step (104) to shorten another prefabricated denture tooth 4.

[0094] Optionally, following the sixth work step 105, the processed prosthetic tooth 4 can then be glued into a suitable tooth socket 2 of a prosthesis base 1 in a seventh work step 106 to produce a dental prosthesis.

[0095] The features of the invention disclosed in the preceding description, as well as in the claims, figures and embodiments, can be essential for the realization of the invention in its various embodiments, both individually and in any combination. Reference symbol list 1 Prosthetic base 2 tooth sockets 3 Palate plate 4 prosthetic teeth 6 Coronal side 8 Cervical side 9 Cervical volume to be removed 10 Calculation module 12 bracket 14 Pump 16 Intake manifold 18 suction cups 20 lasers 22 heads 24 laser beam 26 Movement device 28 Control 30 bracket 32 recording 34th level Step 100: Reading in existing data on the shape of a dental prosthesis Step 101: Creating a virtual model of the denture teeth Step 102: Calculating the cervical area to be removed Step 103: Calculating the movement sequence of the laser beam Step 104: Controlling the movement of the laser beam according to the calculation Step 105: Removing the processed, shortened denture tooth Step 106: Connecting the prosthetic tooth to a prosthetic base

Claims

[1] Method for shortening prefabricated denture teeth for dental prostheses in the form of partial or complete dentures, the method being characterized by the following steps: A) Creating or providing a virtual 3D model of a dental prosthesis with a virtual model of a prosthesis base (1) as a gingival imitation and with at least one virtual model of at least one machined prosthesis tooth (4) to be arranged in the prosthesis base (1) to replicate at least one tooth; B) Calculating a cervical volume (9) to be cut off from at least one prefabricated denture tooth (4) with known geometry by comparing the at least one virtual model of the at least one machined denture tooth (4) with at least one virtual model of the at least one prefabricated denture tooth (4) using a CAD method, wherein the cervical volume (9) to be cut off is located on a cervical side (8) of the at least one prefabricated denture tooth (4); C) Calculating at least one cutting surface for separating the cervical volume (9) to be cut off calculated in step B) from the at least one prefabricated denture tooth (4), wherein the at least one cutting surface includes an interface between the cervical volume (9) to be cut off from the at least one prefabricated denture tooth (4) and the respective remaining denture tooth (4); D) Fixing at least one prefabricated denture tooth (4) with a holder (12, 30), wherein the prefabricated denture tooth (4) consists of at least 90 wt% plastic in at least a cervical area; E) Removal of the cervical volume (9) to be cut off calculated in step B) from the at least one fixed prefabricated prosthetic tooth (4) by at least one cut with a laser beam (24), wherein the laser beam (24) is guided relative to the at least one fixed prosthetic tooth (4) and / or the prosthetic tooth (4) in the holder (12, 30) is guided relative to the laser beam (24) according to the at least one calculated cutting surface in step C). [2] Method according to claim 1, characterized by , that at least one cross-sectional surface is realized by at least one cross-sectional plane. [3] Method according to any of the preceding claims characterized by, that in step B) several cervical volumes (9) to be cut from several prefabricated denture teeth (4) with known geometry are calculated, in step D) several prefabricated denture teeth (4) are fixed and in step E) the several prefabricated denture teeth (4) are cut with the laser beam (24), wherein preferably the cutting surfaces in step B) are chosen such that each of the denture teeth (4) processed in step E) receives an individual cervical shape. [4] Method according to any of the preceding claims characterized by , that at least one prefabricated prosthetic tooth (4) is made entirely or at least in a cervical area of ​​plastic. [5] Method according to claim 4 characterized bythat the plastic has at least one inorganic pigment and / or at least one inorganic filler, wherein preferably the plastic has up to 5 wt%, and most preferably between 1 wt% and 5 wt% of the at least one inorganic pigment and / or the at least one inorganic filler. [6] Method according to any of the preceding claims characterized by , that a head (22) of a laser (20) is used to generate the laser beam (24) and / or an optic is moved to move the laser beam (24) relative to the at least one fixed prosthetic tooth (4). [7] Method according to any of the preceding claims characterized by , that a CO2 laser is used to generate the laser beam (24) and / or the laser beam (24) has a power of less than 1 kW, preferably a power between 4 W and 400 W, particularly preferably a power between 20 W and 200 W. [8] Method according to any of the preceding claims, characterized by , that to fix the at least one prefabricated prosthetic tooth (4) in step D) the at least one prefabricated prosthetic tooth (4) is clamped with the holder (12, 30). [9] Method according to claim 8 characterized by that the holder (30) has a negative shape for receiving the at least one prefabricated prosthetic tooth (4), wherein preferably the negative shape has a negative shape that fits coronal areas of the at least one prefabricated prosthetic tooth (4) and / or the negative shape is made of an elastic material, in particular rubber or silicone. [10] Method for manufacturing dental prostheses in the form of partial or complete dentures, the dental prostheses comprising several denture teeth (4) and a denture base (1) as a gingival imitation for placement on gingiva, wherein the denture teeth are fixed in the denture base (1), the method comprising a method according to one of the preceding claims and the method further characterized by the following steps: F) Fixing the at least one prosthetic tooth (4) processed in step E) into at least one suitable tooth socket (2) of a prosthetic base (1), preferably the at least one prefabricated prosthetic tooth (4) being glued into the at least one suitable tooth socket (2) of the prosthetic base (1). [11] Method according to any of the preceding claims characterized by, that no further processing of the cut surface produced with the laser beam (24) takes place before the at least one prosthetic tooth (4) processed in step E) is attached to the prosthetic base (1). [12] Device for implementing a method according to one of the preceding claims, comprising the device a calculation module (10) for performing the calculations of process steps B) and C). a holder (12, 30) for fixing at least one prefabricated prosthetic tooth (4) in a unique position, a laser (20) to generate the laser beam (24), a controllable motion device (26) with which the laser beam (24) of the laser (20) is movable relative to the holder (12, 30) by making the holder (12, 30) movable relative to the laser (20) and / or making the laser (20) movable relative to the holder (12, 30) and / or making the laser beam (24) movable relative to the holder (12, 30) by means of a movable head (22) or a movable optic, and a control (28) for controlling a movement sequence of the movement device (26), such that the laser beam (24) of the laser is movable relative to the holder (12, 30) according to the calculation according to step C) of the calculation module (10), so that the at least one prosthetic tooth (4) fixed in the holder (12, 30) in the unique position is cut on the cervical side (8) with the laser beam (24) according to the cutting surface. [13] Device according to claim 12, characterized bythat the laser (20) is a CO2 laser with a power of less than 1 kW, preferably with a power between 4 W and 400 W, particularly preferably with a power between 20 W and 200 W. [14] Device according to claim 12 or 13, characterized by that the holder (30) comprises a negative mold for receiving the at least one prefabricated prosthetic tooth (4), wherein preferably the negative mold has a negative shape that fits coronal areas of the at least one prefabricated prosthetic tooth (4) and / or the negative mold is made of an elastic material, in particular rubber or silicone. [15] Device according to any one of claims 12 to 14, characterized by , that the laser beam (24) of the laser (20) is movable with the controllable motion device (26) in such a way that a cut with a profile can be produced, in particular with a step profile and / or a wave profile.

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