Dental unit and method for producing a denture base

Description

[0001] The invention relates to a dental unit with an artificial tooth for insertion into a denture base and a method for producing a denture base.

[0002] Today, a high standard can be observed in the treatment of patients with partial or full dental dentures. The dentist prepares the intended situation on the patient, while the (partial) denture is usually fabricated in an external laboratory or an in-office laboratory by a dental technician according to the dentist's specifications. The quality of the denture depends largely on the craftsmanship of the dental technician, who must take the dentist's specifications into account when fabricating the denture, as well as the quality of these specifications.

[0003] Furthermore, preparing the patient for prosthetic treatment is often inconvenient. Examples include several appointments with the treating dentist, during which impressions of the situation to be treated must be taken, which serve as negative models for the dental technician. The subsequent additional impressions are time-consuming and often the reason for faulty prosthetic treatment. Typically, two or three impression sessions are required before the dental technician can begin the actual fabrication of the prosthesis.

[0004] WO2011 / 066895 A1 relates to a method for the automated production of dental prostheses, comprising the steps of providing a digital data set of the individual prosthesis to be produced, digital separation of the model into dental arch and gum, production of the dental arch from ceramic and plastic by means of milling technology or production of the prosthesis base by generative or abrasive methods from predominantly (meth)acrylate-based plastics, the connection of the dental arch and the gum by gluing or joining or a combination of gluing and joining.

[0005] EP 2 111 180 A1 relates to a method for producing a base part of an artificial denture or an artificial denture comprising a base part, comprising the step of shaping the base part using a rapid prototyping method, such as 3D lithography and in particular 3D laser lithography. Furthermore, a method for creating a data set indicating the shape of a base part of an artificial denture is disclosed, in which a gum area or a model thereof is scanned and / or a model of a base part is scanned and / or the shape of the base part is simulated on a computer.

[0006] EP 1 864 627 A2 discloses a method for producing dental prostheses based on a digitalized, virtual model that reproduces the jaw situation, comprising the steps of digital recording of the jaw situation and relationships, digital setup (automatic as an option), generation of a split negative mold (rapid manufacturing) from the data of the digital tooth setup, insertion of the prefabricated teeth / prefabricated tooth units into the opened negative molds, closing the negative molds, and filling the remaining cavities with denture plastic.

[0007] EP 1 444 965 A2 relates to a method for producing dental prostheses, comprising the steps of recording and digitizing (scanning) the 3-dimensional anatomical conditions in the oral cavity, if necessary recording and digitizing (scanning) the 3-dimensional data of bite templates including bite rims, if necessary recording the jaw data that is normally taken from the patient to adjust the articulator, processing the data set obtained in such a way that the relevant anatomical structures for a virtual tooth setup are determined and a virtual model is obtained as a data set, followed by the selection of the 3-D data sets of prefabricated, previously scanned teeth from a further data set, virtual setup of the teeth in the virtual model as a second data set and either followed by a transfer of the virtual setup to the model by means of either a positioning template (e.g.milled or rapid prototyped) or direct positioning of the prefabricated teeth on the model, fixation of the teeth on the model, attachment of the denture base or in another alternative, followed by direct fabrication of the denture base - according to the data of the virtual tooth setup - with positioning aids for the final correct positioning and fixation of the prefabricated teeth.

[0008] WO 2008 / 005432 A2 discloses a system for manufacturing at least a part of a prosthesis. The system comprises a three-dimensional scanning device for scanning a surface of a prosthesis template, and a computer-readable medium with a computer program for receiving data from the scanning device, a 3-dimensional model of the surface, and optionally modifying the 3-dimensional model and / or adding functions to the 3-dimensional model. The system also comprises processing for generating at least a part of the prosthesis from a selected material, taking the 3-dimensional model into account. The processing can be material-removing or material-building.

[0009] WO 2015 / 078701 discloses an artificial tooth for use in a denture base, which has a visible outer part and an inner part which, when inserted, is arranged within the denture base. The tooth is designed such that a tooth edge is formed between the outer part and the inner part. The tooth edge is designed such that a tooth edge is formed between the outer part and the inner part. The tooth edge is designed such that there is an angle change at it. In this respect, it is a clearly recognizable and defined edge or line. There is no continuous transition between the outer part and the inner part of the tooth at the tooth edge. Rather, there is a sudden change in the angle.Furthermore, the artificial tooth is designed such that the inner part is free of undercuts with respect to the insertion direction in which the tooth is inserted into the denture base. However, artificial teeth manufactured according to WO 2015 / 078701 have the disadvantage that a clearly defined tooth edge with a change in angle must always be present in order to manufacture the artificial tooth and insert it correctly into the denture base. Therefore, there is a need, particularly for such an automatic method for manufacturing a dental prosthesis, to also provide artificial teeth without a tooth edge with a change in angle.

[0010] An artificial tooth is known from US 2016 / 0095677. This document describes a virtual dataset for the tooth, which defines a virtual gingival line.

[0011] The object of the invention is to provide a dental unit with suitable artificial teeth in order to improve the manufacturing process of a denture base, whereby in particular an automated process for manufacturing a denture base is to be made possible.

[0012] The object is achieved by a dental unit according to claim 1 or a method for producing a denture base according to claim 5.

[0013] The inventive dental unit according to claim 1 comprises an artificial tooth for insertion into a denture base and a virtual data set of this tooth. When inserted into the denture base, the artificial tooth has a visible outer part and an inner part arranged within the denture base. The virtual data set of the tooth comprises data of the outer geometry and the surface geometry of the tooth, respectively.

[0014] The inner part of the artificial tooth must be designed in such a way that there are no undercuts in the direction of insertion or insertion of the tooth into the denture base. This significantly simplifies insertion. In particular, the creation of the cavity in the denture base, which accordingly also has no undercut in the direction of insertion, is significantly easier.

[0015] According to the invention, a virtual gingival line is formed in the virtual data set of the tooth, in the area without undercuts in the direction of the inner part. This defines the transition between the outer part, which is visible in the inserted state, and the invisible inner part of the tooth. Since the virtual gingival line is arranged in the undercut-free area of ​​the tooth, according to the invention, it is easy to insert the tooth into the denture base in the insertion or insertion direction. In extreme cases, the virtual gingival line can precisely describe the line from which the area begins where there is no longer any undercut, based on the insertion or insertion direction of the tooth into the denture base.

[0016] With the help of the dental unit according to the invention, it is thus possible to clearly define teeth that do not have a tooth edge where an angle change occurs. Furthermore, it is possible to position the virtual gingival line at different heights depending on the implanted condition of the tooth. For example, a gingival line can be positioned lower, corresponding to a rather older tooth with slightly receding gums. This allows for precise adaptation to the patient's situation in a very simple manner.

[0017] The artificial tooth according to the invention is further developed in such a way that the virtual gingival line is formed completely circumferentially. The virtual gingival line is thus a closed line. This is particularly advantageous for automated manufacturing processes such as CAD / CAM processes.

[0018] Furthermore, it is preferable that the artificial tooth be machined only on the outer part to customize its shape. This has the advantage of creating a clearly defined inner part, which is particularly important for automation, and thus allows the cavities in the denture base to be created automatically. The shape and depth of the cavities are thus clearly defined.

[0019] In the artificial tooth according to the invention, the inner part preferably has a minimum outer radius of at least 0.6 mm. The smallest radius present in the region of the inner part is thus 0.6 mm or more. This is particularly advantageous for the production of the cavity in a denture base. It is particularly preferred that the minimum outer radius is at least 1.0 mm and in particular at least 1.25 mm.

[0020] Furthermore, the inner part of the artificial tooth is asymmetrical. In particular, the inner part is not rotationally symmetrical. This prevents incorrect insertion into the denture base.

[0021] For the complete production of a prosthesis, a large number of teeth according to the invention are available in a library from which a specific set of teeth can be selected.

[0022] In the method according to the invention for producing a denture base, at least one artificial tooth according to the invention is virtually embedded in a virtual denture base or a virtual gingiva. In the next step, a cavity edge is defined such that it at least partially, in particular completely, overlaps with the virtual gingival line. Preferably, the virtual gingival line is transferred to the denture base to define the cavity edge. This continues to be done virtually, so that a virtual cavity edge is created for the at least one tooth according to the invention in the virtual denture base. Preferably, the cavity edge is congruent with the virtual gingival line in the case of a completed denture with the inserted artificial tooth. After defining the at least one cavity edge, the real denture base is produced by creating a cavity in a denture base body.This is achieved, in particular, by milling out the cavity. The cavity is preferably manufactured using a CAD / CAM process. According to the invention, the cavity edge serves to define a tool movement for CAM processes. The cavity edge serves as a limit curve for creating the milling strategy. The milling paths are generated in CAM from the limit curve and the known cavity geometry. For the manufacturing process, the required milling process parameters (speed, feed, lateral and depth infeed, etc.) known from the state of the art are defined.

[0023] It is particularly preferred that the virtual cavity edge be defined by virtually subtracting the tooth from the virtual denture base. This allows for a simple transfer of the virtual gingival line to the virtual denture base, thus defining the cavity edge.

[0024] In a particularly preferred embodiment, the cavity to be created in the denture base, particularly using CAD / CAM technology, is designed to complement the underside or inner part of the tooth. This allows an adhesive gap to be defined that has a constant width or thickness across the entire adhesive surface. This has the advantage of ensuring extremely precise and clearly defined insertion of the tooth into the cavity. Furthermore, due to the clearly defined adhesive gap, the volume of the adhesive gap is also clearly defined, allowing a predetermined amount of adhesive to be introduced into the cavity, thus preventing adhesive from being squeezed out in the area of ​​the cavity or tooth edge. This has the advantage that the post-processing steps are simplified or can possibly be eliminated entirely.

[0025] In order to enable good automation, it is particularly preferred that the cavities in the denture base are designed in such a way that no undercuts occur in the direction of insertion or insertion of the tooth.

[0026] The cavities are preferably created using a cutting tool such as a milling tool. It is preferred that the tool has a machining radius equal to or greater than the minimum outer radius of the inner part of the artificial tooth. For example, a milling head has a diameter of 1.2 mm if the minimum outer radius of the inner part is at least 0.6 mm.

[0027] It is particularly preferred that several teeth, in particular all teeth of a dental arch, are virtually embedded in the virtual prosthesis base using the method according to the invention described above with reference to one tooth. Accordingly, it is preferred that all associated cavity edges are defined, in particular, by virtual subtraction, and then, as described above with reference to one tooth, all associated cavities are preferably produced using a CAD / CAM process.

[0028] Before embedding the at least one tooth according to the invention into a virtual prosthesis base, the following method steps can preferably be carried out: Recording of an oral patient situation by means of an impression or digital recording, if necessary digitization of the oral patient situation, selection of the teeth forming the dental prosthesis from an ideally calculated setup according to a corresponding setup concept of teeth or groups of teeth, whereby a virtual setup of the teeth is obtained which is virtually positioned in a space that takes into account the recorded patient situation, virtual embedding of the teeth arranged in the virtual setup in a virtual prosthesis base.

[0029] The setup concept is developed specifically for each patient, for example by a treating physician.

[0030] Partial or full dentures are removable, partially removable or fixed dentures.

[0031] The impression of the situation in the patient's mouth (patient situation) can be created, in particular, using impression materials. According to the invention, the impression can be advantageously used for the initial impression, the second impression (functional impression), and bite registration.

[0032] In the method according to the invention, the impression can be taken using conventional devices, so-called impression trays. An impression tray that allows for mucosal-congruent support is particularly suitable. The marginal areas should be reduced. The impression tray should be able to accommodate impression material and be capable of accommodating a vertical mechanism for bite adjustment as well as posterior geometries for bite fixation.

[0033] In one embodiment of the present invention, the digital recording of the patient situation is carried out by means of imaging, in particular optical, methods such as camera recording, computer tomography, ultrasound.

[0034] In a further embodiment of the method according to the invention, the library contains designs of dental arches, tooth shapes, tooth sizes, tooth shapes, sizes, and combinations thereof, as can be found, for example, in VITA Form Cards No. 1694 and No. 1756. Complete setups and / or modular setups for all bite classes according to Angle are preferably included in the library. If desired, the library can also contain designs of the gingiva in different age characteristics.

[0035] The method according to the invention advantageously enables the adaptation of the dental arch to the individual jaw arch width of the patient by taking into account virtual hinges which are extended by a function in the form of a movement element (inward and outward movement), for example between teeth 11 and 21 in the upper jaw and teeth 31 and 41 in the lower jaw. The design of the gingiva can be individualized virtually, for example by inserting palatal folds or adjusting the A-line and the etchings. For the palatal folds, stored virtual models of the folds are preferably inserted into the virtual model of the prosthesis. In this case, it can be expedient to individually modify the models according to the design of the prosthesis, for example by stretching or compressing them or by mapping them onto the palate surface.The etching is modified by virtually changing the material thickness near the A-line; the A-line itself can be displayed and changed as a curve or boundary line in the virtual model.

[0036] These procedural steps are described in detail in PCT / EP2013 / 062279.

[0037] The invention is explained in more detail below using a preferred embodiment with reference to the accompanying drawings.

[0038] They show: Fig. 1 is a schematic perspective side view of an artificial tooth according to the invention, Fig. 2 is a schematic perspective rear view of an artificial tooth according to the invention, Fig. 3 is a schematic perspective top view of a cavity in a denture base, Fig. 4 is a schematic sectional view of a tooth inserted into the cavity base, and Fig. 5 is a perspective view of a denture base with partially inserted artificial teeth.

[0039] To produce a complete denture, i.e. a denture base into which artificial teeth are inserted, the following steps are carried out: Recording of an oral patient situation by means of an impression or digital recording, if necessary digitization of the oral patient situation, selection of the teeth forming the dental prosthesis from an ideally calculated setup according to a corresponding setup concept of teeth or groups of teeth, whereby a virtual setup of the teeth is obtained which is virtually positioned in a space that takes the recorded patient situation into account, virtual embedding of the teeth arranged in the virtual setup in a virtual gingiva or virtual prosthesis base, production of the real prosthesis.

[0040] This procedure is described in particular in PCT / EP2013 / 062279.

[0041] This method is further developed according to the invention in such a way that artificial teeth designed according to the invention are used. A corresponding library therefore contains a large number of teeth designed according to the invention. These teeth have different sizes, shapes, etc. A common feature of the artificial teeth according to the invention is, in particular, the design of a virtual gingival line.

[0042] At the Figs. 1 and 2The virtual gingival line 10 is shown in the example of a tooth, which is an incisor. The artificial tooth shown as an example has an outer part 12 and an inner part 14. The outer part 12 is separated from the inner part 14 by the virtual gingival line 10. When the artificial tooth is inserted into the denture base, the outer part 12 is arranged outside the denture base and is visible. The inner part 14 is arranged inside the denture base when inserted and is therefore not visible.

[0043] The virtual gingival line 10 is designed as a self-contained, circumferential line. This virtual gingival line 10 is created with the aid of the virtual dataset of the tooth in the direction of the inner part 14 in the undercut-free area. The virtual gingival line is located in the undercut-free area. The undercut-free area is defined by a line 16. Line 16 defines the boundary of the undercut-free area in the insertion or insertion direction. Figure 1 Below line 16, there is no longer an undercut relative to the insertion direction (arrows 17) into the denture base. An undercut is made above line 16.

[0044] For the production of a denture base 20 ( Fig. 3), the individual teeth are first subtracted from a virtual denture base. A denture base 20 with a corresponding cavity 22 for each tooth can thus be virtually created. The virtual denture base 20 thus has a cavity 22 that is delimited by a cavity edge 24. The cavity edge 24 is created by the virtual subtraction of the tooth from the denture base 20 and corresponds to the virtual gingival line 10.

[0045] The cavities 22 in the denture base 20 are preferably manufactured using CAD / CAM processes. These processes utilize the cavity edge 24 to define the milling paths or the movement paths of other tools. This enables a very precise and automatic production of the cavities 22.

[0046] Since the inner part 14 of the teeth is in an insertion direction 26 ( Fig. 4) of the teeth into the cavities 22 has no undercuts, simple assembly or simple insertion / gluing into the cavities 22 is possible. The cavities 22 also have no undercut in the corresponding insertion direction 26. The insertion direction 26 runs essentially perpendicular to the denture base. With the denture positioned in the patient's oral cavity, the insertion direction would run essentially vertically.

[0047] The cavity 22 is designed to be complementary to the inner part, so that an exact position definition of the tooth in the cavity 22 is provided. By a complementary design of the inner part 14 and the cavity 22, a bonding gap 28 ( Fig. 4 ) that has a constant width across its entire surface. Therefore, the volume of the adhesive gap and thus the required amount of adhesive are precisely known.

[0048] In Fig. 4, in which the tooth and also the denture base 20 are shown in section, the virtual gingival line 10 is also shown. The part of the virtual gingival line 10 shown as a solid line runs in front of the drawing plane with respect to the section surface of the tooth, and the part shown as a dashed line runs behind the drawing plane.

[0049] For the complete manufacture of a prosthesis, several cavities 22 are provided in the prosthesis base 20 ( Fig.5 ). A clearly defined amount of adhesive is first applied to the individual cavities, and then the corresponding teeth are inserted into the cavities 22 in the insertion direction 26. When the teeth are inserted, the cavity edge 24 and the virtual gingival line 10 lie one above the other.

Claims

1. Tooth unit comprising an artificial tooth for insertion into a denture base (20) and a virtual data set of the tooth, the artificial tooth having an outer part (12) visible in the inserted state and an inner part (14) arranged inside the denture base (20) in the inserted state, and the inner part (14) being designed to be non-symmetric, the inner part being designed such that relative to a direction of insertion in which the artificial tooth is inserted into the denture base (20), no undercuts are present at the inner part, the virtual data set of the tooth corresponding to its outer geometry, and the virtual data set of the artificial tooth having a virtual gingiva line (10) in the region which is free of undercuts in the direction of the inner part (14), said gingiva line defining the transition from the outer part (12) to the inner part (14), the artificial tooth having no tooth edge at which a change of angle occurs and the virtual gingiva line (10) extends completely circumferentially.

2. Tooth unit of claim 1, characterized in that the virtual gingiva line (10) is arranged depending on the desired appearance of a certain tooth.

3. Tooth unit of claim 1 or 2, characterized in that the inner part (14) is designed to be rotationally non-symmetric.

4. Tooth unit of one of clams 1 to 3, characterized in that the inner part (14) has a minimum outer radius of at least 1.0 mm and particularly preferred at least 1.25 mm.

5. Method for producing a denture base using a tooth unit according to one of claims 1 to 4, comprising the following steps: virtual embedding of at least one tooth of the tooth unit into a virtual denture base (20), transferring the virtual gingiva line (10) onto the denture base to define a cavity edge (24), and producing the real denture base (20) by forming at least one cavity (22) in a denture basic body.

6. Method for producing a denture base of claim 5, wherein the cavity edge (24) is defined by virtual subtraction of the tooth from the virtual denture base (20).

7. Method for producing a denture base of claim 5 or 6, wherein the cavity (22) is made using CAD / CAM methods, the cavity edge (24) serving to define a tool movement.

8. Method for producing a denture base of one of claims 5 to 7, wherein, for forming a bonding gap (28) of constant width, the cavity (22) is produced to be complementary to the lower side of the tooth, and / or wherein the cavities (22) are produced free of undercuts in the direction of insertion (26) of the tooth.

9. Method for producing a denture base of one of claims 5 to 8, wherein a tool, in particular a milling tool, for forming the cavities (22) has a working radius that is equal to or greater than the minimum outer radius of the inner part (14) of the artificial tooth to be inserted into the cavity.

10. Method for producing a denture base of one of claims 5 to 9, wherein a plurality of teeth, in particular all teeth of a dental arch are embedded in a virtual manner, all associated cavity edges (24) are defined and all associated cavities (22) are produced.

11. Method for producing a denture base of one of claims 5 to 10, wherein, prior to the virtual embedding of the at least one tooth, at least the following steps are performed: determining an oral situation of a patient by making impressions or by digital imaging, possibly, digitizing the oral situation of a patient, selecting the teeth forming the dental prosthesis from an ideally calculated arrangement according to a corresponding arrangement concept of the teeth or of sets of teeth, whereby a virtual arrangement of the teeth is obtained that is positioned virtually in a space that gives consideration to the patient's situation determined, virtually embedding the teeth set up in the virtual arrangement into a virtual denture base.