DE102023004830A1 - Method for producing a partial dental prosthesis, and a partial dental prosthesis produced by this method. - Google Patents

Abstract

The present invention relates to a method for the mechanical production of a partial dental prosthesis, consisting of at least one basal support (1), a model cast prosthesis with at least one retention grid (3), at least one artificial gingiva (4), and at least one dental crown (6). The invention also relates to a partial dental prosthesis produced by this method.

Description

The present invention relates to a method according to the preamble of patent claim 1. The invention also relates to a partial dental prosthesis produced by this method.

The common approach to creating and manufacturing partial dentures is a combination of digital and analog work. Typically, either the patient's oral cavity is scanned using an intraoral scanner, or an impression of the patient's jaw is taken, from which a negative impression is created as a plaster model and digitized using a commercially available dental scanner. Both options result in a virtual three-dimensional model of the patient's jaw as a digital dataset, which forms the basis for the virtual creation of a denture.

Methods for the digital setup of various dental components and their mechanical production using CAD-CAM technology (CAD = Computer-Aided Design; CAM = Computer-Aided Manufacturing) are known, among other things, from the DE 10 2009 056 752 A1 , the WO 2012/021816 A1 or the WO 2013 124 452 A1 basically known.

From the DE 103 04 757 B4 A method for producing dental prostheses is known in which a dental prosthesis is virtually positioned in a virtual model and the production of a prosthesis base takes place on the basis of the virtual model.

A partial denture usually consists of at least one dental crown and a cast denture, which secures the complete denture in the patient's mouth, as well as a basal support and artificial gingiva. Fixation is achieved by means of at least one clasp that grips an adjacent tooth and/or at least one secondary telescope, which is placed on a primary telescope. In this document, gingiva refers to the patient's gums. The basal support, together with the area of the retention grid of the cast denture and the artificial gingiva, is referred to as the denture saddle.

The DE 200 09 320 U1 describes such a partial denture with labial clasp.

The creation of a model cast prosthesis and a dental crown is usually done digitally with subsequent additive or subtractive manufacturing. In this document, digital creation refers to the virtual construction of a three-dimensional geometry as a CAD model using common dental CAD software such as exocad DentalCAD.

Depending on the material used to manufacture the crown, it can be permanently connected to the metal retention grid of the model cast prosthesis by soldering, screwing or gluing.

The EP 3 166 532 B1 discloses an extraoral method for the production of a dental prosthesis from a denture base and several denture teeth by, among other things, manually applying a fluid, viscous mass to the basal surface and creating a bond between the denture base and the denture teeth by curing the fluid, viscous mass.

For this purpose, the patient's virtual jaw model is usually manufactured from plastic using additive lithographic 3D printing. A thin plastic basal overlay is typically fabricated beneath the denture base, i.e., beneath the retention grid area of the metal model cast denture. For this purpose, a thin plastic plate is heated and manually applied over the tooth gap area of the patient's 3D-printed jaw model, where it is shaped. The basal overlay is necessary for a better feel on the natural gingiva and to make it easier to reline the entire denture at a later date, as the natural gingiva beneath a denture recedes over time.

All common methods for fabricating a partial denture have the significant disadvantage that a patient's digital jaw model must be available in analog form and therefore first fabricated. Furthermore, the manual creation of a basal support and the connection of the individual components of the partial denture require a high degree of sensitivity and involve considerable manual effort.

The invention is based on the object of eliminating all disadvantageous aspects in the production of commercially available partial dentures and of enabling the production of their components completely digitally and of producing them by means of mechanical manufacturing processes.

According to the invention, this object is achieved as stated in claim 1.

Advantageous further developments emerge from the subclaims and the description, in particular in conjunction with the drawings.

A method is created with which a partial dental prosthesis can be digitally created and individually adapted to the patient using at least one additive or subtractive manufacturing process.

Instead of a laborious and not exactly reproducible manual process, the invention creates a method for the digital creation and mechanical production of a partial dental prosthesis from the basal support to the dental crown, which significantly accelerates and facilitates the process.

In addition to the personnel and time required, the material consumption is significantly reduced, as the virtual jaw model of a patient no longer needs to be made of plastic. This saves resources, material and manufacturing costs, and optimizes the entire process chain.

As with previous methods, the basis for the inventive production of a partial denture is the electronic dataset of a virtual three-dimensional model of a jaw. This can be created, for example, by scanning a negative impression of a patient's upper or lower jaw using a commercially available dental scanner. Preferably, however, the dataset of a jaw is created using an intraoral scan of the patient's oral cavity.

The electronic data set of a jaw can now be imported into a dental CAD software such as exocad DentalCAD and, based on this, a dental crown can be created in the CAD module and positioned based on the insertion direction.

For better positioning, a digital articulator is conceivable, which, for example, uses artificial intelligence to simulate the chewing movement and automatically checks and determines the optimal position of the chewing surface of a crown.

A model cast prosthesis can then be created and positioned, for example, in the model casting module of exocad DentalCAD by specifying the insertion direction and the area of the retention grid. The retention grid can have various and even customized recess shapes, which can be defined and created, for example, in the expert mode of the exocad dental software. This can also be used to add so-called retention posts to create the desired retention pins. The distance between the underside of the retention grid of the model cast prosthesis and the surface of the natural gingiva of the tooth gap on the jaw model can also be specified. The distance is preferably four millimeters.

It is advantageous, for example, to create a dental crown before creating a model cast prosthesis in order to be able to adjust the width of the retention grid of this model cast prosthesis exactly to the width of the respective dental crown.

The resulting electronic dataset, consisting of the jaw model, the partial denture, and at least one crown, can then be imported, for example, into the dental CAD software OnyxCeph. There, the electronic dataset can be subtracted from, for example, a previously extruded model of the same dataset, resulting in the basal support, digitally created according to the invention and corresponding to the natural gingiva of the tooth gap in the jaw model. This also determines the position of the basal support, which can then be connected, for example, in exocad DentalCAD, to the previously created retaining pins.

Using, for example, two retaining pins of a basal support, at least one created and positioned dental crown and at least one retention grid of the created and positioned model cast prosthesis, at least one artificial gingiva can now be created and positioned, for example in the CAD module of exocad DentalCAD by adding a periodontal pocket and defining its area.

Subsequently, the components of a partial denture, consisting of at least one basal support, a model cast denture with at least one retention grid, at least one artificial gingiva and at least one dental crown, can be individually output and saved.

The production of a partial denture is particularly advantageous if its prosthetic saddle is adapted to the surface of the natural gingiva above the dental bone, also called os, of the patient's tooth gap and is created according to the geometric dimensions of the tooth gap.

The last step of the method according to the invention is the manufacture of the individual components of the partial dental prosthesis by means of at least one additive or at least one subtractive manufacturing process.

It is advantageous to design the procedure in which the basal support and the artificial Gingiva made of pink plastic, in particular polymethyl methacrylate (PMMA), polyethylene terephthalate (PET), polyamides (PA), printing resins of similar or identical composition to pro3dure printodent® GR 14.2 HI or DETAX FREEPRINT® denture impact or other common materials for lithographic 3D printing technology or subtractive processes.

Furthermore, for economic and material-specific reasons, it is advantageous to manufacture the model cast prosthesis additively, in particular by means of selective laser melting, from a medical stainless steel, in particular from a cobalt-chromium alloy.

During the design phase, it is important to consider that the metal model cast prosthesis has a groove in the transition area between the metal of the model cast prosthesis and the plastic of the artificial gingiva, for example, into which the plastic can protrude. Any remaining micro-gap between the different materials can be closed, for example, by the capillary action of the composite material.

If the patient is prone to intolerances, it is advantageous to manufacture the model cast prosthesis additively, particularly by means of selective laser melting, from titanium due to the biocompatible properties of the material.

Additive or subtractive manufacturing of the model cast prosthesis made of polyetheretherketone (PEEK) is also conceivable.

For economic reasons, it is also advantageous to manufacture the dental crown from plastic, especially polymethyl methacrylate (PMMA), using subtractive milling technology.

In principle, additive manufacturing, for example using lithographic 3D printing technology, or subtractive manufacturing using milling technology of at least individual components of a partial dental prosthesis made of ceramic materials such as zirconium dioxide is also conceivable.

The use of multi-material composites or, for example, plastic filled with ceramic particles to manufacture at least individual components of a partial denture is also conceivable. This could, for example, increase the strength characteristics and service life of the denture.

To simplify the assembly and insertion of the components of a partial denture and to ensure virtually error-free assembly, it is proposed to provide the basal support with retaining pins or fixing elements whose horizontal cross-sectional areas correspond to the recesses in the retention grid of the partial denture, and the retaining pins or fixing elements extend through these recesses. Furthermore, it is proposed to provide the artificial gingiva on the underside with depressions or recesses that correspond to and enclose the portion of the retaining pins or fixing elements of the basal support that extends above the retention grid. Furthermore, the dental crown has a recess on the underside that corresponds to the shape of the artificial tooth stump on the upper side of the artificial gingiva or the retaining pins.

Preferably, the basal support is provided with at least two cylindrical support pins, which prevent horizontal twisting or displacement of the upper prosthesis component in the X and Y directions. This can also be achieved, for example, by using at least one cuboid-shaped or oval-cylindrical support pin due to the angular or oval cross-sectional area. However, it is advisable to distribute the horizontal forces across multiple pins to reduce the load on a single pin and maintain a positive fit through additional pins, even if one pin breaks off.

It is also advantageous to provide the basal support with at least one fixation element, which, in contrast to the aforementioned retaining pins, not only provides a positive connection but also a force-locking clamp or click connection with the artificial gingiva of the prosthesis or, alternatively, with the dental crown. This also prevents vertical displacement in the Z-direction and thus ensures the desired positioning.

For reasons of space, the retaining pins or fixing elements are preferably positioned centrally on the basal support along the alveolar ridge corresponding to the retention holes of the model cast prosthesis and the recesses of the artificial gingiva below the tooth crown.

In addition, the retaining pins or fixing elements preferably have grooves which, when the components of a partial denture, which have previously been provided with a preferably liquid composite, are put together, form a reservoir for the excess composite and at the same time serve as an additional retention surface, resulting in a more resistant composite with greater strength after the composite has hardened.

Thus, the invention ensures that the basal support, the model cast prosthesis, the artificial gingiva and the dental crown can be placed on top of each other and fixed by at least one positive connection and permanently connected by means of adhesive bonding.

The positive fit between the retaining pins of the basal support and the recesses of the retention grid as well as the artificial gingiva and, if applicable, the dental crown allows the curing of an adhesive, including its capillary action, to take place properly and ensures the bonding of the basal support with the artificial gingiva and the model cast prosthesis and, if applicable, the dental crown until the adhesive has completely cured.

To bond the components of a partial denture, a 0.03 mm, but a maximum of 0.05 mm thick adhesive layer is recommended, for example with the dual-curing BLUE FIX double crown adhesive Gold, which is already taken into account as an adhesive gap during the virtual creation of the partial denture in the CAD software.

To bond the components of a partial denture, it is further proposed to use a resin for lithographic 3D printing, which may also have been used to create the artificial gingiva and/or the basal support. This resin can be applied, for example, with a brush or dosing syringe and then cured with a suitable light source.

As an alternative to bonding using dental cementation, the components of a partial denture can also be bonded using cold polymerization, for example using PMMA-containing plastics.

It is also advantageous, especially when bonding the basal support, to use an adhesive that can be removed without residue, for example, in an ultrasonic bath. This allows, for example, the basal support to be separated from the remaining components of the partial denture after some time, in the case of normal receding of the natural gingiva, and to be made thicker to accommodate the receding.

The basis for this could, for example, be an impression taken by the dentist in the patient's mouth, with the impression material depicting the space between the underside of the basal support and the surface of the receding natural gingiva. The impression of the basal addition can then be digitized by scanning it using a standard dental scanner. The resulting virtual three-dimensional model can then be attached to the underside of the data set of the basal support known from production and digitally connected using standard CAD software. This newly created data set can then be manufactured, preferably using additive manufacturing. The appropriately relined basal support can now form a positive connection with the remaining components of the partial denture and be permanently bonded using adhesive.

Alternatively, after some time, in the case of the usual receding of the natural gingiva, the patient's jaw can be digitized without the partial denture, for example, using intraoral scanning. The resulting digital jaw model can then be additively manufactured from plastic, for example, using lithographic 3D printing. The space between the underside of the basal support and the surface of the receding natural gingiva can then be manually filled on the plastic model, for example, with pink plastic. The relined part of the basal support can now be bonded to the partial denture and cured in a light curing unit.

Both variants ensure that the partial denture according to the invention can be adjusted at any time in accordance with the receding gums after some time in the event of normal receding gums.

• 1 zeigt den Querschnitt einer partiellen Zahnprothese, welche über der natürlichen Gingiva 8 und dem Os 9 positioniert ist und dessen basale Auflage 1 mit einem Halterungsstift 2 versehen ist, der mit dem Retentionsgitter 3 und der künstlichen Gingiva 4 formschlüssig verbunden ist.
• 2 zeigt ebenfalls den Querschnitt einer partiellen Zahnprothese, welche über der natürlichen Gingiva 8 und dem Os 9 positioniert ist und dessen basale Auflage 1 mit einem Halterungsstift 2 versehen ist, der mit allen Bestandteilen der partiellen Zahnprothese formschlüssig verbunden ist.
• 3 zeigt eine basale Auflage 1 mit zwei Halterungsstiften 2, die mittig entlang des Kieferkamms positioniert sind und jeweils eine ovale Grundfläche 10, sowie jeweils drei Rillen 11 an der Mantelfläche aufweisen.
• 4 zeigt eine basale Auflage 1 in der Vorderansicht, deren Halterungsstift 2 drei Rillen 11 an der Mantelfläche aufweist.

The invention will be described in more detail below with reference to four drawings. They show:

• 1 shows the cross-section of a partial denture, which is positioned over the natural gingiva 8 and the bone 9 and whose basal support 1 is provided with a holding pin 2, which is positively connected to the retention grid 3 and the artificial gingiva 4.
• 2 also shows the cross-section of a partial denture, which is positioned over the natural gingiva 8 and the os 9 and whose basal support 1 is provided with a holding pin 2, which is positively connected to all components of the partial denture.
• 3 shows a basal support 1 with two holding pins 2, which are positioned centrally along the alveolar ridge and each have an oval base 10 and three grooves 11 on the lateral surface.
• 4 shows a basal support 1 in the front view, the holding pin 2 of which has three grooves 11 on the lateral surface.

More precisely, 1 the cross-section of a completely digitally created partial dental prosthesis, the basal support 1 of which is positioned on the natural gingiva 8 above the bone 9 and has a holding pin 2 which projects through a precisely dimensioned recess in the retention grid 3 of the model cast prosthesis and projects form-fittingly into the precisely dimensioned depression on the underside of the artificial gingiva 4. On the upper side, the artificial gingiva 4 has an artificial tooth stump 5 which projects into the precisely dimensioned depression of the tooth crown 6. The thicker dividing lines both between the basal support 1 and the retention grid 3 of the model cast prosthesis and between the retention grid 3 and the artificial gingiva 4, as well as between the artificial gingiva 4 and the tooth crown 6 indicate individual adhesive layers 7, each with a layer thickness of up to 0.05 mm.

It would also be advantageous to design the partial denture in such a way that the retaining pin 2 extends not only through the retention hole of the retention grid 3, but also through a recess in the artificial gingiva 4 and into the recess of the denture. This ensures that all essential components of a partial denture are directly connected to the basal support 1, at least in a form-fitting manner, and permanently fixed by means of adhesive.

Furthermore, 2 a completely digitally created partial dental prosthesis in cross-section, the basal support 1 of which is created in such a way that its holding pin 2 protrudes through a precisely dimensioned recess in the retention grid 3 of the model cast prosthesis as well as through a precisely dimensioned recess in the artificial gingiva and protrudes into the precisely dimensioned depression on the underside of the tooth crown. The thicker dividing lines between the basal support 1 and the retention grid 3 of the model cast prosthesis as well as between the retention grid 3 and the artificial gingiva 4, as well as between the artificial gingiva 4 and the tooth crown 6 also mark the individual adhesive layers 7, each with a layer thickness of up to 0.5 mm, preferably up to 0.05 mm.

The basic edition 1 from 3 is digitally created in such a way that it has two holding pins 2, which are positioned centrally along the alveolar ridge and each have an oval base 10 and several grooves 11 on the outer surface in order to create, in addition to the positive connection, an optimal adhesive, material-fit connection with, in this embodiment, at least two provided tooth crowns 6 and a dimensionally accurate artificial gingiva 4 as well as the retention grid 3 of the model cast prosthesis.

The front view of a basal support 1 is shown in 4 shown, wherein the holding pin 2 has three grooves on the outer surface in order to enable the best possible adhesive connection with other components of the partial denture.

According to the invention, the basal supports of the 1 , 2 , 3 and 4 Particularly preferably, they are manufactured layer by layer using additive manufacturing technology, in particular using lithographic 3D printing technology. Preferably, subtractive manufacturing processes can also be used.

List of reference symbols

1

Basal support

2

retaining pin

3

Retention grid

4

artificial gingiva

5

artificial tooth stump

6

dental crown

7

adhesive layer

8

natural gingiva

9

Os

10

oval base

11

groove

QUOTES CONTAINED IN THE DESCRIPTION

This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 10 2009 056 752 A1 [0003]
• WO 2012/021816 A1 [0003]
• WO 2013 124 452 A1 [0003]
• DE 103 04 757 B4 [0004]
• DE 200 09 320 U1 [0006]
• EP 3 166 532 B1 [0009]

Claims (10)

A method for producing a partial dental prosthesis consisting of at least one basal support (1), a model cast prosthesis with at least one retention grid (3), at least one artificial gingiva (4), and at least one dental crown (6), comprising the following steps: - Creating an electronic data set for a virtual three-dimensional model of a jaw to which a partial dental prosthesis is to be attached, - Virtually creating and positioning at least one dental crown (6), - Virtually creating and positioning a model cast prosthesis with at least one retention grid (3), - Virtually creating and positioning at least one basal support (1) between the natural gingiva (8) of the tooth gap of a digital jaw model and the retention grid (3) of a model cast prosthesis, - Virtually creating and positioning at least one artificial gingiva (4) corresponding to the surface of the retention grid (3) of a model cast prosthesis and the underside of at least one dental crown (6), - Manufacturing the components of a partial Dental prosthesis by means of at least one additive or subtractive manufacturing process according to the virtually created data sets based on the jaw model. Method according to the preceding claim, characterized in that the basal support (1) is produced and positioned in such a way that it forms at least one positive connection or at least one force-fitting connection with at least one of the further components of a partial dental prosthesis. Method according to the preceding claim, characterized in that the basal support (1) is produced and positioned in such a way that its underside rests on the natural gingiva (8) of the tooth gap and that it has at least one holding pin (2) or at least one fixing element which either projects through at least one dimensionally accurate recess in the retention grid (3) and projects at least positively into at least one depression in the artificial gingiva (4) or projects through at least one dimensionally accurate recess in the retention grid (3) and the artificial gingiva (4) and projects at least positively into at least one depression in the tooth crown (6). Method according to one of the preceding claims, characterized in that the artificial gingiva (4) is created and positioned in such a way that it covers the area of the retention grid (3) and has at least one dimensionally accurate depression or recess on the underside, which encloses the part of the at least one holding pin (2) or fixing element of the basal support (1) extending above the retention grid (3). Method according to one of the preceding claims, characterized in that the components of a partial dental prosthesis are produced and positioned in such a way that an adhesive gap for an adhesive layer (7) of up to 0.5 mm, preferably up to 0.05 mm, is taken into account both between the basal support (1) and the retention grid (3) of the model cast prosthesis, as well as between the retention grid (3) and the artificial gingiva (4), and between the artificial gingiva (4) and the tooth crown (6). Method according to one of the preceding claims, characterized in that the basal support (1) is created digitally by means of CAD software by subtracting a first electronic data set, consisting at least of a jaw model and a model cast prosthesis, from a second, previously downwardly extruded CAD model of the same data set or from another CAD object which fills at least the intermediate area between the jaw model and the retention grid of the model cast prosthesis of the first electronic data set. Method according to one of the preceding claims, characterized in that the basal support (1) is manufactured layer by layer by means of additive manufacturing technology, in particular by means of lithographic 3D printing technology. Partial dental prosthesis, characterized in that it is produced according to at least one of the methods claims 1 until 7 is manufactured. Partial dental prosthesis according to one of the preceding claims, characterized in that the basal support (1) is made of at least one ceramic or polymerized material, or of a multi-material composite of at least one polymerized material component with ceramic or metallic components. Partial dental prosthesis according to one of the preceding claims, characterized in that the basal support (1) is detachable from the remaining part of the prosthesis and can be renewed, or replaced by a polymerized or ceramic Material addition can be expanded and adapted to a changing oral cavity situation.

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