WO2009010543A1

WO2009010543A1 - Device for reshaping hard and soft tissues of the jaw and dentition

Info

Publication number: WO2009010543A1
Application number: PCT/EP2008/059337
Authority: WO
Inventors: Philippe Tardieu; Veerle Pattijn
Original assignee: Materialise Dental N.V.
Priority date: 2007-07-16
Filing date: 2008-07-16
Publication date: 2009-01-22
Also published as: GB0713746D0

Abstract

Reshaping devices and methods of their production are described that: contain the outline of a new gingiva border; contain the outline of a tooth stripping operation; contain a planned bone contour; contain at least a part of an outline of a tooth set-up for verifying a tooth trimming operation; contain the full shape of new crowns; contain a shape of an existing dentition after trimming. The reshaping device may be either tooth-supported or mucosa-supported.

Description

DEVICE FOR RESHAPING HARD AND SOFT TISSUES OF THE JAW AND

DENTITION

FIELD OF THE INVENTION The current invention relates to dental treatments for achieving optimal aesthetical appearance, which are used for instance in case of crowded teeth, partially or fully edentulous dentitions, or aesthetically less pleasing tooth configurations. In these cases dental anatomical structures (e.g. soft tissue, bone crest, teeth) must be shaped/adapted according to a new configuration in order to result in an aesthetically pleasing dentition. The current invention also includes a device that can guide such reshaping, which is based on a computer simulation of the desired aesthetic end result (e.g. dentition, bone and surrounding soft tissues e.g. the gingiva). The present invention includes methods of designing and making the device and software for use in the design method.

BACKGROUND TO THE INVENTION

In aesthetic dental treatments it is very important that the teeth in the modified dentition have nice emergence profiles, which are determined by shape (typically scalloped) of the soft tissues forming the interdental papillae. Therefore - in most cases - the gingiva contour must be reshaped to correspond with the new tooth configuration.

Gingiva contouring may be accomplished by soft tissue excision or by flap procedures. The type of treatment depends on the amount of soft tissue reduction needed, the width of keratinized gingiva present and the need for osseous reshaping. Once the new tooth set-up is planned, the gingiva contour can be planned as well in function of the desired emergence profiles of the teeth. This new gingiva contour determines the desired level of the bone crest, since the distance between the gingiva and the crest of the bone is assumed to be constant (e.g. approximately 3 mm as reported in literature). This distance is known as the biological space. Thus, to achieve the desired gingival level, the bone crest should be reshaped according to the outline of the planned gingival level, at an offset of approximately 3 mm, unless the reshaping of the gingiva is limited and can be achieved by a gingivectomy. In clinical practice reshaping the bone crest and the gingiva in function of the desired tooth set-up is not so easy. Once a surgical flap has been opened for accessing the bone, the dental surgeon looses all reference points with respect to the gingiva contour, which makes it very difficult to reshape the bone in function of the planned gingiva border.

For fully dentate or partially edentulous jaws the preparation (e.g. trimming or stripping) of the teeth is an essential step and influences the aesthetics of the final tooth set-up (for example for orthodontics). According to current practices for prosthetics the dentist trims/strips the teeth and takes an impression, which is sent to the dental lab for creating the ceramic restoration. If trimming is not properly performed the dental lab will be forced to create a restoration which is not optimal with respect to aesthetics, or will be forced to ask the dentist to further trim the teeth and make a new impression. The current invention helps the dental surgeon in reshaping either the bone crest, the gingiva contour, or the teeth in function of the planned aesthetical tooth set-up.

SUMMARY OF THE INVENTION

The present invention provides a treatment planning arrangement for dental treatments of a patient, comprising: a workstation having a processing unit and a display unit, a memory able to store a virtual three-dimensional model of teeth and/or associated anatomical structures representing the dentition of a patient and the surrounding tissue, and software executable by the processing unit to allow display and manipulation of the model on the display unit, the software including navigation tools enabling a user to interactively manipulate the displayed model and to simulate a variety of dental operations, and apparatus for production of a reshaping device that contains the planned bone contour and/or the outline of the new gingiva border and/or modified outline of the teeth.

The dental operations may include any of, or any combination of: simulating a gingivectomy, indicating a desired crown length, allowing positioning of digital casts relative to each other by means of a bite registration, splitting mal-positioned teeth from the mucosa and repositioning, the movement of at least one tooth in the model relative to other teeth in the model to obtain a new dentition, and simulating stripping or reducing of one or more of the teeth to allow orthodontic tooth movement, resulting in a new gingiva contour.

The present invention also provides a method of digital treatment planning for a patient requiring dental treatment, using a workstation having a processing unit, a user interface including a display unit and software executable by said processing unit, comprising: obtaining and storing a three-dimensional virtual model of the dentition of the patient and surrounding soft tissue, displaying the virtual model on the display unit; simulating a variety of dental operations, and producing a reshaping device that contains the planned bone contour and/or the outline of the new gingiva border and/or modified outline of the teeth.

The dental operations may include any of, or any combination of simulating a gingivectomy, indicating a desired crown length, allowing positioning of digital casts relative to each other by means of a bite registration, splitting mal-positioned teeth from the mucosa and repositioning, the movement of at least one tooth in the model relative to other teeth in the model to obtain a new dentition, and simulating stripping or reducing of one or more of the teeth to allow orthodontic tooth movement, resulting in a new gingiva contour.

The present invention includes a computer program product, e.g. software, which when executed on a processor implements any of the methods of the present invention or provides an adapted workstation for carrying out any of the methods of the present invention. The computer program product may be stored on any suitable signal storage medium, such as solid state memory, tape memory, disk memory, e.g. a magnetic disk memory such as a hard disk, an optical disk such as a CD-ROM or DVD-ROM or may be stored in computer memory such as a RAM or transmitted over a network such as a Local Area Network or Wide Area Network, e.g. the Internet or an Intranet or Extranet.

The present invention also provides a reshaping device: containing the outline of a new gingiva border; or containing the outline of a tooth stripping operation; or containing a planned bone contour; or containing at least a part of an outline of a tooth set-up for verifying a tooth trimming operation; or containing the full shape of new crowns; or containing a shape of an existing dentition after trimming.

The reshaping device may be either tooth-supported or mucosa-supported.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention will be described, by way of example only, with reference to the accompanying drawings in which:

Figure 1 shows an example of a gingiva border reshaping guide (1); Figure 2 shows an example of a bone reshaping guide (2).

Figure 3 shows a computer based system for carrying out embodiments of the invention.

DESCRIPTION OF PREFERRED EMBODIMENTS

The present invention will be described with respect to particular embodiments and with reference to certain drawings but the invention is not limited thereto but only by the claims. Any reference signs in the claims shall not be construed as limiting the scope. The drawings described are only schematic and are non-limiting. In the drawings, the size of some of the elements may be exaggerated and not drawn on scale for illustrative purposes. Where the term « comprising » is used in the present description and/or claims, it does not exclude the presence of other elements or steps. Where an indefinite article is used when referring to a singular noun e.g. « a », « an » or « the », this includes a plural of that noun unless something else is specifically stated.

Furthermore, the terms first, second, third and the like in the description and/or in the claims are used for distinguishing between similar elements and not necessarily for describing a sequential or chronological order. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that the embodiments of the invention described herein are capable of operation in other sequences than described or illustrated herein. The current invention provides a device to transfer the new desired shape of dental anatomical parts (soft tissue, bone crest, teeth...) from the computer planning to the mouth of the patient, with the aim of obtaining an aesthetically pleasing dentition as well as a method of doing the same.

According to the invention the patient's dentition and surrounding soft tissue should be digitized. Then, using a software program an aesthetic virtual tooth set-up can be created. This virtual tooth set-up may be created by means of any suitable method of which one is obtaining digital versions of teeth from a virtual tooth library taking into account patient specific information (e.g. opposing dental arch, facial characteristics, patient requests...). Library teeth may represent morphological characteristics related to age, wear, gender, etc. They may have varying colour, shape and translucency, etc. Alternatively the teeth and soft tissue in the digitized model may be digitally manipulated (e.g. moved, reshaped, etc.). Another option is digitizing a physical model, e.g. a wax-up of the aesthetic virtual tooth set-up as made in a dental lab on the physical model of the patient's current dentition (or jaw in case of edentulous patients).

An important part of the virtually designed aesthetic tooth set-up is the gingiva contour, i.e. the border between the soft tissue and the tooth or teeth. Based on the planned tooth set-up and gingiva border, which may be shown to the patient for approval, dedicated devices can be manufactured to assist the dentist/surgeon in the transfer of the planning to the mouth of the patient.

The devices according to the invention have two main characteristics: (1) they will be supported by or anchored to fixed structures (implants, teeth or tooth stumps, bone, soft tissue...), and (2) they contain the outline of the planned shape for one or more of the following anatomical parts: soft tissue, bone crest, teeth. These characteristics will ensure a unique and correct positioning of the device in the mouth of the patient, allowing an accurate transfer of the planned shape (e.g. gingiva outline, labial tooth outline, incisal tooth outline...). The device can serve as a means either for visual control during the reshaping, or to delineate (draw) the new shape onto the anatomical part that must be reshaped, or to guide the reshaping tool.

The reshaping of the dental anatomical parts may include a reduction of the current shape (e.g. trimming, stripping, resection...) and/or a build-up (e.g. adding, veneering...) and/or a movement (e.g. orthodontic tooth movement...) to obtain the desired shape.

The device can be directly produced by means of computer aided manufacturing techniques, such as numerical control techniques of shaping devices, e.g. by milling, rapid prototyping, selective laser sintering, etc. Another method for manufacturing the device is by using computer aided manufacturing techniques to make a physical model of the planned dentition including one or more of the following components: teeth, bone, soft tissue, and using dental lab techniques for production of the device itself.

Based on the computer planning of the desired new tooth set-up and gingiva border the dentist/surgeon can determine whether or not the bone crest should be reshaped and whether or not a gingivectomy should be performed.

In case the bone crest needs to be reshaped, guides may be produced containing the outline of the planned bone crest shape. Typically this crestal bone contour may be determined by creating an offset at 3 mm towards the bone of the desired (planned) gingiva contour. These guides will aid the surgeon to trim the bone. Afterwards a guide containing the gingiva border will be used to reposition the soft tissue flap according to the aesthetically planned set-up.

If a gingivectomy is required, the desired soft tissue margin can be marked in the mouth of the patient. Alternatively, the guide itself may be used during the gingivectomy. Guides that outline the tooth set-up are used to verify if each tooth is sufficiently trimmed to ensure that a predetermined minimal space, required for the prosthetic reconstruction or tooth movement, is available. Typically the teeth are trimmed back with an offset of approximately 1 mm. However, based on the original tooth positions and their expected final positions according to the virtually created set-up it may be necessary to trim back the teeth further or not at all. In the software program used to create the aesthetic tooth set-up means may be included to verify whether or not the amount of trimming required exceeds a user-defined value. Such a value may differ in the mesio-distal, the bucco-lingual and the axial direction. Depending on the results of this verification a user may decide to extract one or more teeth and replace them with artificial elements.

According to another feature of the invention, the guides may also be used as a mold for the fabrication of a temporary prosthesis. Such a temporary device may be placed over the remaining dentition.

Illustrative examples

For example, in the case of a fully or partially dentate patient, having an aesthetically less pleasing tooth set-up, due to the occurrence of too short teeth, a typical dental treatment may be a crown lengthening procedure including a gingivectomy. Therefore an impression is taken from the patient's dentition and surrounding soft tissue. From this impression a plaster cast is poured to be scanned optically. This scanned in digital representation will result in a digital 3D model of the patient's dentition and surrounding tissue. Using computer planning software the gingivectomy is simulated by indicating the desired crown length. This will result in a new gingiva contour. To transfer this planning (which can be discussed with and approved by the patient) to the patient's mouth a reshaping device is produced by means of for example stereo lithography techniques. This reshaping device may either be tooth- supported or mucosa-supported, and will contain the outline of the new gingiva border. The reshaping device is positioned into the mouth of the patient and used either for marking the gingival excision line or for guiding the dental tool during the gingivectomy.

A patient having one or more mal-positioned teeth will typically be treated orthodontically to obtain an aesthetically pleasing dentition. Impressions are taken from the patient's upper and lower jaw as well as a bite registration. These impressions and bite registration may be digitized by means of volumetric scan such as with a micro CT scanner, resulting in 3D models (typically in stl-format). These 3D models are imported in a dedicated software package for visualization and simulation purposes. A first step is the positioning of both digital casts relative to each other by means of the bite registration, using any suitable algorithm of which N-point registration and global (point cloud based) registration algorithms are but two. In a next step the mal-positioned teeth are split from the mucosa and repositioned to obtain an aesthetically pleasing dental arch. It may be needed to strip (reduce) one or more of the teeth to allow the orthodontic tooth movement. This stripping operation is simulated within the software. Based on this computer planning (i.e. including simulation of tooth stripping operation) a reshaping device is designed and produced. This reshaping device will be supported on the tooth (as positioned before starting the orthodontic movement) and will contain the outline of the needed stripping operation. The tooth stripping operation in the mouth of the patient can be guided by the reshaping device itself, or by a marking indicated on the respective teeth by means of the reshaping device. After stripping the teeth the orthodontic tooth movement can be initiated.

In case of a fully or partially dentate patient having an aesthetically less pleasing tooth set-up due to the occurrence of crowded teeth, a typical dental treatment includes a prosthetic restoration. The patient's dentition and jawbone is digitized by taking a volumetric scan such as a CT scan of the patient's mouth. Using existing software, like for instance SimPlant (Materialise Dental NV), these volumetric images, e.g. CT images can be imported and 3D models of jawbone and teeth can be created digitally. Additional an optical scan of the plaster model of the patient's dentition made by means of an impression can be taken and will result in an accurate 3D surface model, e.g. a 3D model such as an stl-model of teeth and surrounding soft tissue. This stl- model is imported into the SimPlant project. Moreover a texture mapping algorithm may be used to colour the digital 3D model of teeth and soft tissue (plaster cast) based on a 2D intra-oral photograph, which will improve the visual representation of the gingiva border. Using computer planning software a new aesthetic tooth set-up is created based on a virtual teeth library and visualized, and the new gingiva contour is drawn as well. To obtain this new gingiva contour in reality it may be necessary to reshape the underlying bone crest. By making a certain offset such as a 3 mm offset of the gingiva contour towards the bone within the computer planning software, the desired bone contour is visualized. To transfer this new bone contour to the patient a reshaping device is produced that is supported on the patient's teeth and contains the planned bone contour. Based on the digital comparison of the new tooth set-up with the patient's existing tooth set-up the necessary reshaping of the teeth for the prosthetic restoration is determined, by taking into account a minimal required space for the prosthetic restoration. To transfer the new tooth shapes to the mouth of the patient one or more reshaping devices are produced containing outlines of the areas to be trimmed. These areas may then be marked on the patient's teeth and guide the dentist in trimming the teeth. Besides these also other reshaping devices may be made: (1) devices that contain the outline (partially) of the new planned tooth set-up and aid the surgeon in verifying the tooth trimming operation, and (2) devices that contain either the full shape of the new crowns (tooth set-up) or the shape of the existing dentition after trimming, which can together serve as moulds for creation of a temporary restoration. The reshaping devices may be made by any suitable CAD-CAM manufacturing technique such as by rapid prototyping.

Implementation

A treatment planning apparatus for dental treatments of a patient for use with the present invention may include a workstation having a processing unit and a display unit, a memory able to store a virtual three-dimensional model of teeth and/or associated anatomical structures representing the dentition of a patient and the surrounding tissue, and software executable by the processing unit to allow display and manipulation of the model on the display unit. The software may further include navigation tools enabling a user to interactively manipulate the displayed model and to simulate a variety of dental operations including simulating a gingivectomy and indicating a desired crown length, or to allow positioning of digital casts relative to each other by means of the bite registration, using any suitable algorithm of which N- point registration and global (point cloud based) registration algorithms are but two and then splitting the mal-positioned teeth from the mucosa and repositioning to obtain an aesthetically pleasing dental arch. This may include the movement of at least one tooth in the model relative to other teeth in the model to obtain a desired dentition.

Stripping (reducing) of one or more of the teeth may be performed to allow orthodontic tooth movement. This stripping operation is simulated within the software. These procedures will result in a new gingiva contour or a new tooth setup or an adapted bone contour.

The workstation may have access to a library of virtual, three-dimensional orthodontic or dental elements such as teeth, i.e. a memory may store a set of virtual, individual three-dimensional tooth objects, and the software allows a user to access these elements, place these elements in the model of the dentition of the patient at user optional, arbitrary positions, and to display simultaneously both the elements and the model. The software may be provided to display a screen permitting a user to provide, e.g. draw a new gingiva contour. To obtain this new gingiva contour in reality it may be necessary to reshape the underlying bone crest. By making a certain offset such as a 3 mm offset of the gingiva contour towards the bone within the computer planning software, the desired bone contour is visualized.

In addition apparatus is provided for production of a reshaping device that is supported on the patient's teeth and/or partly on the patient's mucosa and contains the planned bone contour and/or the outline of the new gingival border and/or modified outline of the teeth. The reshaping device contains the outline of the new gingiva border. For example the apparatus may be a rapid prototyping machine, e.g. an apparatus for carrying out stereo lithography. Based on the digital comparison of the new tooth set-up with the patient's existing tooth set-up the necessary reshaping of the teeth for the prosthetic restoration is determined, by taking into account a minimal required space for the prosthetic restoration. The reshaping devices are produced containing outlines of the areas to be trimmed.

Besides these also other reshaping devices may be made: (1) devices that contain the outline (partially) of the new planned tooth set-up and aid the surgeon in verifying the tooth trimming operation, and (2) devices that contain either the full shape of the new crowns (tooth set-up) or the shape of the existing dentition after trimming, which can together serve as moulds for creation of a temporary restoration.

In addition a scanning system may be provided for scanning of the dentition of the patient or a model of the dentition. A further part of the scanning system can comprise a device for intra-oral, in-vivo scanning of a human patient, e.g. using optical techniques. FIG. 3 is a schematic representation of a computing system and work station of the type described above which can be utilized with the methods and in a system according to the present invention including computer programs. A computer 150 is depicted which may include a video display terminal 159, a data input means such as a keyboard 155, and a graphic user interface indicating means such as a mouse 156. Computer 150 may be implemented as a general purpose computer, e.g. a UNIX workstation or a personal computer. Computer 150 includes a Central Processing Unit ("CPU") 151, such as a conventional microprocessor of which a Pentium processor supplied by Intel Corp. USA is only an example, and a number of other units interconnected via bus system 154. The bus system 154 may be any suitable bus system - FIG. 3 is only schematic. The computer 150 includes at least one memory. Memory may include any of a variety of data storage devices known to the skilled person such as random-access memory ("RAM"), read-only memory ("ROM"), non- volatile read/write memory such as a hard disc as known to the skilled person. For example, computer 150 may further include random- access memory ("RAM") 152, read-only memory ("ROM") 153, as well as a display adapter 1512 for connecting system bus 154 to a video display terminal 159, and an optional input/output (I/O) adapter 1511 for connecting peripheral devices (e.g., disk and tape drives 158) to system bus 154. Video display terminal 159 can be the visual output of computer 150, which can be any suitable display device such as a CRT -based video display well-known in the art of computer hardware. However, with a desk-top computer, a portable or a notebook-based computer, video display terminal 159 can be replaced with a LCD-based or a gas plasma-based flat-panel display. Computer 150 further includes user interface adapter 1510 for connecting a keyboard 155, mouse 156, optional speaker 157. Relevant data may be input directly into the computer using the keyboard 155 or from storage devices such as 158, after which a processor carries out a method in accordance with the present invention. For example memory stores a virtual three-dimensional model of teeth and/or associated anatomical structures representing the dentition of a patient and the surrounding tissue, and software is provided that is executable by the processing unit to allow display and manipulation of the model on the display device, the software including navigation tools enabling a user to interactively manipulate the displayed model and to simulate a variety of dental operations including any of simulating a gingivectomy, indicating a desired crown length, allowing positioning of digital casts relative to each other by means of a bite registration, splitting mal-positioned teeth from the mucosa and repositioning, the movement of at least one tooth in the model relative to other teeth in the model to obtain a new dentition, and simulating stripping or reducing of one or more of the teeth, (e.g. to allow orthodontic tooth movement, resulting in a new gingiva contour or a new tooth setup or an adapted bone contour). The software may include existing software, like for instance SimPlant (Materialise Dental NV), for importing CT images and with which 3D models of jawbone and teeth can be created digitally. Additional an optical scan of the plaster model of the patient's dentition made by means of an impression can be taken and resulting in an accurate 3D surface model, e.g. a 3D model such as an stl-model of teeth and surrounding soft tissue, that is imported into the SimPlant project. Moreover the software may include a texture mapping algorithm to colour the digital 3D model of teeth and soft tissue (plaster cast) based on a 2D intra-oral photograph, which will improve the visual representation of the gingiva border. Computer planning software can be provided to create a new aesthetic tooth set-up based on the virtual teeth library and visualized, and the new gingiva contour is drawn as well. The results of the method, i.e. for example a description of the reshaping device, may be transmitted to a further near or remote location, e.g. a CAD/CAM processing facility to manufacture the template in accordance with the details provided by computer 150 to allow production of a reshaping device that contains the planned bone contour and/or the outline of the new gingiva border and/or modified outline of the teeth. A CAD/CAM manufacturing unit 1516 may also be connected via a communications adapter 1517 to bus 154 connecting computer 150 to a data network such as the

Internet, an Intranet, a Local or Wide Area network (LAN or WAN), or a CAN. The manufacturing unit 1516 may receive an output value or support descriptor file directly from computer 150 running a computer program for support design in accordance with the present invention or a value or descriptor file derived from such an output of computer 150. Alternatively, the unit 1516 may receive the relevant design data indirectly on a suitable signal storage medium such as a diskette, a replaceable hard disc, an optical storage device such as a CD-ROM or DVD-ROM, a magnetic tape or similar. Computer 150 also includes a graphical user interface that resides within machine- readable media to direct the operation of computer 150. Any suitable machine -readable media may retain the graphical user interface, such as a random access memory (RAM) 152, a read-only memory (ROM) 153, a magnetic diskette, magnetic tape, or optical disk (the last three being located in disk and tape drives 158). Any suitable operating system and associated graphical user interface (e.g., Microsoft Windows, Linux) may direct CPU 151. In addition, computer 150 includes a control program 1517 that resides within computer memory storage 1516. Control program 1517 contains instructions that when executed on CPU 151 allow the computer 150 to carry out the operations described with respect to any of the methods of the present invention.

Those skilled in the art will appreciate that the hardware represented in FIG. 3 may vary for specific applications. For example, other peripheral devices such as optical disk media, audio adapters, or chip programming devices, such as PAL or EPROM programming devices well-known in the art of computer hardware, and the like may be utilized in addition to or in place of the hardware already described. In the example depicted in FIG. 3, the computer program product for carrying out the method of the present invention can reside in any suitable memory. However, it is important that while the present invention has been, and will continue to be, that those skilled in the art will appreciate that the mechanisms of the present invention are capable of being distributed as a computer program product in a variety of forms, and that the present invention applies equally regardless of the particular type of signal bearing media used to actually carry out the distribution. Examples of computer readable signal bearing media include: recordable type media such as floppy disks and CD ROMs and transmission type media such as digital and analogue communication links.

Accordingly, the present invention also includes a software product which when executed on a suitable computing device carries out any of the methods of the present invention. Suitable software can be obtained by programming in a suitable high level language such as C and compiling on a suitable compiler for the target computer processor.

Claims

1. A treatment planning arrangement for dental treatments of a patient, comprising: a workstation having a processing unit and a display unit, a memory able to store a virtual three-dimensional model of teeth and/or associated anatomical structures representing the dentition of a patient and the surrounding tissue, and software executable by the processing unit to allow display and manipulation of the model on the display unit, the software including navigation tools enabling a user to interactively manipulate the displayed model and to simulate a variety of dental operations including any of simulating a gingivectomy, indicating a desired crown length, allowing positioning of digital casts relative to each other by means of a bite registration, splitting mal-positioned teeth from the mucosa and repositioning, the movement of at least one tooth in the model relative to other teeth in the model to obtain a new dentition, and simulating stripping or reducing of one or more of the teeth, and apparatus for production of a reshaping device that contains the planned bone contour and/or the outline of the new gingiva border and/or the modified outline of the teeth.

2. A treatment planning arrangement according to claim 1, wherein the simulating stripping or reducing of one or more of the teeth is to allow orthodontic tooth movement resulting in a new gingiva contour or a new tooth setup or an adapted bone contour.

3. A treatment planning arrangement according to claim 1 or 2, the workstation having access to a library of virtual, three-dimensional orthodontic or dental elements such as teeth, and the software is adapted to allow a user to access these elements, place these elements in the model of the dentition of the patient at user optional, arbitrary positions, and to display simultaneously both the elements and the model.

4. A treatment planning arrangement according to any previous claim; wherein the software allows display of a screen permitting a user to provide a new gingiva contour.

5. A treatment planning arrangement according to claim 4; wherein a screen is provided to obtain the new gingiva contour by reshaping the underlying bone crest in the model.

6. A treatment planning arrangement according to claim 5, wherein the software is adapted a make an offset of the gingiva contour towards the bone and to visualize the bone contour.

7. A treatment planning arrangement according to any of claims 3 to 6, wherein a memory stores a set of virtual, individual three-dimensional tooth objects.

8. A method of digital treatment planning for a patient requiring dental treatment, using a workstation having a processing unit, a user interface including a display unit and software executable by said processing unit, comprising: obtaining and storing a three-dimensional virtual model of the dentition of the patient and surrounding soft tissue, displaying the virtual model on the display unit; simulating a variety of dental operations including any of simulating a gingivectomy, indicating a desired crown length, allowing positioning of digital casts relative to each other by means of a bite registration, splitting mal-positioned teeth from the mucosa and repositioning, the movement of at least one tooth in the model relative to other teeth in the model to obtain a new dentition, and simulating stripping or reducing of one or more of the teeth, and producing a reshaping device that contains the planned bone contour and/or the outline of the new gingiva border and/or modified outline of the teeth.

9. A method according to claim 8, wherein the simulating stripping or reducing of one or more of the teeth is to allow orthodontic tooth movement resulting in a new gingiva contour or a new tooth setup or an adapted bone contour.

10. A method according to claim 8 or 9, the workstation having access to a library of virtual, three-dimensional orthodontic elements such as teeth, further comprising allowing a user to access these elements, place these elements in the model of the dentition of the patient at user optional, arbitrary positions, and displaying simultaneously both the elements and the model.

11. A method according to any of the claim 8 to 10; further comprising displaying a screen and that allows a user to provide a new gingiva contour.

12. A method treatment according to claim 11; wherein providing the screen to obtain the new gingiva contour includes reshaping the underlying bone crest in the model.

13. A method according to claim 12, further comprising making an offset of the gingiva contour towards the bone and visualizing the bone contour.

14. A reshaping device obtainable by any of the methods 8 to 13 or by use of the arrangement of any of claims 1 to 7.

15. A reshaping device that contains the outline of a new gingiva border.

16. A reshaping device that contains the outline of a tooth stripping operation.

17. A reshaping device that contains a planned bone contour.

18. A reshaping device that contains at least a part of an outline of a tooth set-up for verifying a tooth trimming operation.

19. A reshaping device that contains the full shape of new crowns.

20. A reshaping device that contains a shape of an existing dentition after trimming.

21. A reshaping device according to any of claims 15 to 20 that is either tooth- supported or mucosa- supported.