DE102013203888B4 - A computer-implemented method for determining the attachment positions of a plurality of archwire engagement members of a dental appliance on associated teeth of a patient and displaying the teeth in linear juxtaposition - Google Patents

Abstract

Computer-implemented method for determining the attachment positions (P) of a plurality of engagement elements (22) for a wire arch (28) of a dental appliance on associated teeth (12) of at least one jaw (36, 38) of a patient,
characterized in that
on a display of a computer on the one hand an occlusal view (30) and - when the dental apparatus is arranged on the vestibular side of the teeth (12) - on the other hand a vestibular view (32) or - when the dental apparatus is arranged on the oral side of the Teeth (12) - secondly, an oral view (34) of a linear juxtaposition of the teeth (12) is displayed, in which views the engaging elements (22) are also shown.

Description

The invention relates to a computer-implemented method for determining the attachment positions of a plurality of engagement elements for a wire arch of a dental appliance, in particular a dental appliance permanently installed on the teeth, on associated teeth of a patient.

The use of dental appliances, such as dental braces, to correct misaligned teeth is well known in the prior art. In addition to the removable braces that were frequently used in the past, fixed braces are now increasingly being used. These include attacking elements known as “brackets” in technical terminology, which are fastened to the teeth, for example glued in place, and represent attacking points for corrective movements of the teeth. The adjusting forces required for the corrective movements are generated by a wire arch, which is connected to the brackets via engagement elements formed on them and referred to as “slots” in the technical jargon for force transmission. Usually, several archwires are engaged with the brackets one after the other at intervals of several weeks in order to gradually correct the misaligned teeth. The so-called bands are known as another type of attack element, but these are usually only used on molars.

From the DE 10 2011 085 915 A1 discloses a method of manufacturing an auxiliary device for attaching a plurality of engaging elements to an associated plurality of teeth of a patient. The known method also includes, inter alia, the step of determining the attachment positions of the engaging elements on the teeth, and the present invention is concerned with how this step can be carried out in a computer-implemented manner.

A well-known procedure of the type mentioned at the beginning is described on the website "www.lingualtechnik.de" of Lingualtechnik GmbH under the heading "Patients / Treatment process".

In the known method, starting from a plaster model of the actual position of the teeth, a plaster model of the desired position of the teeth is first created by sawing the plaster model of the actual position into individual plaster teeth by a dental technician and so Preserved plaster teeth are rearranged. This plaster model of the target position is then digitized by three-dimensional scanning. On the basis of the three-dimensional digital data model obtained in this way, a tailor-made attack element is then designed and manufactured for each patient with the aid of a computer. The archwire connecting the attachment elements is also custom-made for each patient, using a wire-bending robot.

This method is time-consuming and expensive due to the many steps to be carried out by a dental technician and the fact that the contact elements and the wire arch are custom-made for the respective patient.

The documents also refer to the state of the art DE 698 15 155 T2 and U.S. 2004/0 214 128 A1 pointed out.

It is therefore the object of the present invention to specify a method of the type mentioned at the outset that can be carried out in a simple and cost-effective manner.

• 1a) Erstellen eines dreidimensionalen digitalen Datenmodells der Ist-Stellung der Zähne des Patienten,
• 1b) Transformieren des dreidimensionalen digitalen Datenmodells der Ist-Stellung der Zähne in ein dreidimensionales digitales Datenmodell einer Soll-Stellung der Zähne,
• 1c) für jeden Zahn: Festlegen einer Anfangsposition des zugehörigen Angriffselements als Momentanposition dieses Angriffselements,
• 1d) für jeden Zahn: Durchführen einer Kollisionsprüfung für die jeweiligen Momentanpositionen der Angriffselemente,
• 1e) Verändern der Position wenigstens eines Angriffselements, falls die Kollisionsprüfung für wenigstens ein Angriffselement eine Kollision mit einem Zahn oder/und einem anderen Angriffselement oder/und dem Drahtbogen ergeben hat,
• 1f) Wiederholen der Schritte 1d) und 1e), bis die Kollisionsprüfung für keines der Angriffselemente eine Kollision ergibt oder ein vorbestimmtes Abbruchkriterium erreicht worden ist.

This object can be achieved by a computer-implemented method for determining the attachment positions of a plurality of ready-made contact elements for a substantially planar archwire or one that essentially follows the curve of Spee's curve of a dental apparatus on assigned teeth of at least one jaw of a patient, comprising the steps :

• 1a) Creation of a three-dimensional digital data model of the actual position of the patient's teeth,
• 1b) transforming the three-dimensional digital data model of the actual position of the teeth into a three-dimensional digital data model of a target position of the teeth,
• 1c) for each tooth: determining an initial position of the associated attacking element as the current position of this attacking element,
• 1d) for each tooth: carrying out a collision check for the respective current positions of the attacking elements,
• 1e) changing the position of at least one engaging element if the collision check for at least one engaging element has revealed a collision with a tooth and/or another engaging element and/or the arch wire,
• 1f) repeating steps 1d) and 1e) until the collision check does not result in a collision for any of the attack elements or a predetermined termination criterion has been reached.

In connection with the present invention, the term “assembled” is used in the sense used from "series-produced", ie exactly according to the understanding of the term, which can also be found in the dictionary. A “ready-made attacking element” is accordingly a mass-produced attacking element, ie an attacking element that is available as standard on the market and has been manufactured without knowing the individual shape of the patient's teeth. However, the term “made-up” does not exclude the selection of an attachment element that is suitable for a specific tooth of the patient or a specific tooth position situation of the patient from a large number of ready-made attachment elements. Furthermore, the term “ready-made engagement element” also includes the fact that it is made up of components, for example a base component having the contact surface for the tooth and an engagement component having the slot, which were selected from a large number of ready-made components.

The use of ready-made attack elements, which can therefore be provided cost-effectively, is made possible by the collision check that is used. In the known method, such a collision check is not required, since collisions can be avoided from the outset through the computer-aided production of patient-specific attachment elements and a patient-specific wire bow with a suitable three-dimensional profile. Ready-made wire arches, on the other hand, are usually essentially flat and their width is preferably changed only in the plane in which they run. However, it is also common to bend them slightly out of this plane so that they essentially follow the curve of Spee. However, the radius of curvature of Spee's curve is in the range of the distance from the contact surface of the teeth of the upper and lower jaw to the center of the orbit. It is therefore relatively large, so that slight deviations from the exact course of Spee's curve have no influence on the treatment result or can be corrected without further ado over the course of the treatment, which lasts several weeks. In any event, the radius of curvature is much greater than that of the prior art custom archwires which utilize radii of curvature less than the mesio-distal extent of the patient's smallest tooth.

It should be noted that the course of the archwire used which is essentially flat or essentially follows Spee's curve represents an additional boundary condition which, compared to the prior art, limits the number of freely selectable degrees of freedom when positioning the attack elements and thus the risk of entails collisions.

According to a first variant, the collision status determined as part of the collision check can only be a binary value that indicates whether the attack element considered in each case collides with something else or not. According to a second variant, however, it is also possible to provide additional information about how many and/or what type of other elements the attacking element collides with. For example, the collision status "0" can indicate that there is no collision, while the collision status "1" indicates a collision with another attacking element or the collision status "2" indicates a collision with a tooth of the same jaw and/or the other jaw . Furthermore, the collision status "12" can indicate that there is a collision with both another attacking element and with a tooth. It goes without saying that these are merely examples that can be expanded and/or modified as desired. For example, another collision status can also be determined, which indicates whether a collision occurs between a tooth of the other jaw and the wire arch (e.g. collision status "3") when the two jaws are in the closed position, i.e. the teeth of both jaws are in occlusal contact.

Finally, it is also possible to determine the strength of the collision. This can be done, for example, by determining the volume of the overlapping or interlocking spatial areas of the colliding elements.

As part of the collision check, it may also be necessary to replace at least one of the plurality of engaging elements with another ready-made engaging element or even to remove it completely, i.e. not to provide at least one of the teeth with an engaging element. The latter can be necessary, for example, for teeth with an extreme misalignment that require special treatment. It should be noted that replacing an attacking element with another attacking element and also removing an attacking element entirely are considered to be “changing the position of the attacking element”.

A further simplification compared to the known method results from the fact that the setup, i.e. the target position of the patient's teeth, is determined with computer assistance on the basis of the three-dimensional digital data model of the actual position of the patient's teeth.

Overall, the method can thus be carried out more easily and more cost-effectively in comparison to the known method.

The collision check can be carried out for the actual position and/or the target position of the teeth. If the collision check is carried out for both the actual position and the target position of the teeth, this increases the certainty that the entire treatment will be collision-free. Of course, to be on the safe side, the collision status can also be determined for at least one further tooth position along the treatment path from the actual position to the target position of the teeth.

There are various options for changing the position of an attack element for which the determined collision status indicates a collision with at least one other element:

According to a first option, the engagement element can be moved in the mesio-distal direction, i.e. at a substantially constant distance from the incisal edge or occlusal surface of the respective tooth. The orientation of the engaging element relative to the wire arch preferably remains unchanged in order to be able to prevent the mesio-distal movement from also making it necessary to deform the wire arch.

According to a second possibility, the distance of the engaging element from the incisal edge or occlusal surface of the tooth can be changed, i.e. the engaging element can be moved in the incisal or occlusal direction or in the gingival direction.

According to a third possibility, the distance between the engagement element and the tooth surface can be changed.

Of course, with all three possibilities, the area over which the attacking element can be moved is limited. For example, a predetermined distance limit value can be defined for the third option, which must not be exceeded with regard to the stability of the fastening of the engaging element on the tooth surface as the distance between the engaging element and the tooth surface increases. Furthermore, for the movement of the engaging element in the mesio-distal direction (first option) and/or in the incisal direction or occlusal direction (second option), taking into account the curvature of the tooth surface, limits of the permissible area of the tooth surface within which the engaging element may be arranged , to be determined. The gum line forms a natural border for movements in the gingival direction (second option). In the incisal direction, when determining the limit of the permissible range, the teeth of the respective other jaw can also be taken into account, preferably in such a way that a collision with them in the desired position is ruled out from the outset.

As already mentioned above, a fourth possibility can be used to check whether the collision or collisions can be avoided by using another ready-made attack element.

A fifth possibility may also consist in checking whether an extension of the permitted movements in the gingival direction to areas below the gingival margin, preferably by up to 1 mm below the gingival margin, would make it possible to avoid collisions. This fifth possibility makes use of the fact that the enamel of the tooth crown, on which the engaging element can be attached, extends to a few millimeters below the gum line. In principle, this further possibility could also be viewed as an extension of the second possibility. However, because it requires working in an environment that is difficult to keep dry, it is considered a separate option.

Since the three-dimensional digital data model of the teeth does not allow statements to be made about the course of the tooth surface below the gum line, this course must be modeled in order to use the fifth option. According to a first variant, one can extrapolate the profile of the tooth surface below the gum line starting from the adjacent visible surfaces. According to a second variant, however, any existing X-ray data, preferably three-dimensional X-ray data, can also be adopted. Finally, according to a third variant, it is also possible to estimate the course on the basis of model teeth from a tooth database.

Finally, a sixth possibility can be to dispense with the attachment of the engagement element altogether or at least for the actual position and to subject the tooth in question to special treatment.

Finally, with the oral arrangement of the engagement elements and detection of at least one collision with the archwire, this archwire can be replaced by another. It should be noted here that in the case of an oral arrangement, so-called “mushroom” archwires are usually used, which have a step in both archwire legs at a point corresponding to the position between the third and fourth tooth, or “double mushroom” archwires are used, which also correspond to the position between the fifth and sixth tooth in both archwire legs the position have a step. The steps each run in the archwire plane or in the archwire surface following Spee's curve.

When implementing these options, any gaps that may arise between the tooth surface and a fastening surface of the engagement element intended for attachment to the tooth surface can be filled by the adhesive mediating the attachment when the engagement element is actually attached to the tooth.

In a development, it is advantageous if it is first checked whether an existing collision can be remedied by moving the engaging element in the mesio-distal direction (first option). The movement of the attacking element in the mesio-distal direction has the advantage that all other attacking elements can maintain their respective positions.

If this is not successful, the next step is to check whether an existing collision can be remedied by changing the distance between the attacking element and the incisal edge or occlusal surface of the tooth (second option). The engagement elements assigned to the other teeth of the same jaw must also be moved in order not to have to deform the essentially flat archwire into a three-dimensional shape that deviates from the flat profile or the curve of Spee, which causes forces on the teeth that are difficult to predict and would result in a treatment outcome that is difficult to predict. The movement in the incisal or gingival direction according to the second option can initially only be carried out by a predetermined distance. Then, for the new inciso-gingival position, it can again be checked whether a movement in the mesio-distal direction according to the first possibility leads to freedom from collision. If this is not the case, the engaging elements can be moved again by the predetermined increment in the inciso-gingival direction. If the collision strength was determined as part of the collision check, the attacking element can be arranged in the inciso-gingival direction as the starting point for the renewed collision check at that mesio-distal position for which the collision strength was lowest at the last inciso-gingival level .

If the second option is not successful either, the next step is to check whether an existing collision can be remedied by changing the distance between the contact element and the tooth surface (third option). Here too, as described above for the second option, the procedure can be step-by-step, and here too the starting position for the renewed collision check can be selected as a function of the collision severity last determined.

Even if the distance from the tooth surface changes, at least some of the engaging elements that are associated with the other teeth in the same jaw must also be moved. Care must be taken here that the orientation of the engaging elements relative to the respectively associated tooth surface is not changed or not changed too much in order to prevent excessive torque being exerted on the tooth. Analogous considerations also apply in the case of an attacking element approaching the tooth surface and/or in the event of a change in the distance of an attacking element assigned to another tooth from its tooth surface.

In the case of the third possibility of movement, it must also be taken into account that the stability of the fastening of the engaging element on the tooth surface decreases as the distance between the engaging element and the tooth surface increases.

The above-explained process of positioning the engaging elements can, for example, run automatically, with the various options for changing the position of the engaging element being used one after the other according to a predetermined sequence. As part of the application of at least one of the options, preferably all options, the respective attacking element can be moved step by step, with the increment of the movement being fixed or variable. Furthermore, a collision check can preferably be carried out after each step in order to determine whether collisions could be avoided. If collision avoidance is determined, the automated positioning of the attack elements is terminated. If a collision avoidance can still not be determined when the limits of the permissible movement range of a specific movement possibility are reached, then another movement possibility can be examined with regard to its collision avoidance potential. If all possible movements have been checked without success, the automated positioning of the attacking elements is ended. The latter represents a possibility for the predetermined termination criterion.

After completion of the automated positioning process, the treating dentist can be given the opportunity to influence the position of each individual attack element again “manually”, ie by means of appropriate ones Inputs via an input device of the computer, for example a keyboard, a pointer input device, ie a computer mouse, a trackball, a touchpad or the like, or another suitable input device. A collision check is preferably carried out after each manual entry.

In principle, it is also possible to dispense with the automated positioning and to carry out the positioning exclusively manually, as has been explained above. It is even conceivable to give the treating dentist the option of switching back and forth between the automated and the manual positioning mode.

It should be added at this point that the FA point of the respective tooth can preferably be used as the starting position for the engaging elements in the automated and/or manual positioning of the engaging elements.

It should also be added that the brackets used initially can either be selected automatically, for example depending on the dimensions of the respective tooth. However, it is also possible for the treating dentist to select them.

To make it easier for the treating dentist to record the positioning of all attack elements, it is proposed according to the invention that the computer display shows an occlusal view on the one hand and a vestibular view on the other when the dental apparatus is arranged on the vestibular side of the teeth or when the dental apparatus is arranged on the oral side of the teeth is displayed an oral view of a linear juxtaposition of the teeth, in which views the attacking elements are also shown.

The linear juxtaposition of the teeth can be, for example, a linear development of the desired position of the teeth, in which not only the teeth but also the spaces between the teeth are shown to scale. However, it is also possible to dispense with the true-to-scale representation of the interdental spaces and to represent the teeth in a linear juxtaposition without spacing or in a linear juxtaposition with a fixed, predetermined width of the interdental spaces. The alignment of the teeth in the vestibular or oral view is preferably carried out in such a way that the FA points of all teeth are arranged at the same height, while the teeth in the occlusal view are preferably aligned in such a way that the target contact points of all teeth are on one straight lines are arranged.

Advantageously, the collision status of the contact elements can also be displayed in the occlusal view and the vestibular or oral view. The collision status of an attack element can be identified, for example, by appropriate highlighting, for example coloring. For example, attacking elements in which there is a collision can be displayed in a signal color, for example red, so that, in particular when the teeth and the attacking elements in which there is no collision, and possibly the gums, are displayed in neutral tones, such as shades of grey, catch the eye and are therefore easily recognizable to the viewer.

Furthermore, the gums can also be shown in the occlusal view and the vestibular or oral view.

In a development of the invention, it is proposed that the teeth and/or the attacking elements, and possibly the gums, are displayed in a representation simulating the real appearance based on the three-dimensional digital data model of the target position. This depiction, which simulates nature, can be kept in shades of gray in the manner of a black-and-white photograph in order to increase the contrast, for example to the elements of the attack where there is a collision. In principle, however, it is also possible to represent the teeth only in a stylized manner. The stylized representation can be, for example, a representation of the tooth outline, in particular in the manner of a pencil sketch. The tooth outline can be derived from the three-dimensional digital data model. However, it is also possible to use a tooth outline that is independent of the three-dimensional digital data model.

To further facilitate the detection of the display, the occlusal view can be displayed above the vestibular or oral view when displaying the target position of the teeth of the upper jaw and below the vestibular or oral view when displaying the target position of the teeth of the lower jaw. Furthermore, when displaying both the target position of the teeth of the upper jaw and the target position of the teeth of the lower jaw, the vestibular or oral view of the teeth of the upper jaw can be displayed above the vestibular or oral view of the teeth of the lower jaw.

In order to be able to change the position of each individual contact element manually, the occlusal and vestibular or oral views can be assigned selection areas for selecting the tooth, the type of movement and the direction of movement and, if desired, the amount of movement. The desired designations of the tooth, the type of movement and the direction of movement and, if necessary, the amount of movement can be entered into these selection areas via a keyboard or, for example menu-supported, via a pointer input device. However, in order to be able to change the position of an engaging element with as few inputs as possible, it is preferred if a separate selection area is provided for each direction of movement of each type of movement of each tooth, which can be selected using the pointer input device, with each selection event, for example each mouse click, preferably one Triggers movement of the associated attack element by a predetermined amount of movement.

Advantageously, after each selection event, the collision status of the attacking elements corresponding to the new positions of the attacking elements can also be calculated.

Furthermore, it is preferred if the display of the positions of the attacking elements and their collision status is updated synchronously after each selection event for both displays, i.e. both for the occlusal display and for the vestibular or oral display.

In addition to the selection areas assigned to the individual teeth, at least one further selection area can also be provided, which is assigned to a group of teeth comprising a plurality of teeth. For example, selection areas can be assigned to the vestibular or oral view, which enable a joint movement of all attacking elements in the inciso-gingival direction. With an oral arrangement of the contact elements and a “mushroom”-type wire arch, the occlusal representation can also have three groups of teeth, each of which is assigned common selection surfaces for changing the distance of the contact elements from the tooth surface. When using an archwire of the "double mushroom" type, five such groups of teeth can even be defined.

In order to be able to prevent the treating dentist from moving the contact elements to impermissible positions when manually influencing the positions of the contact elements, the areas of permissible positions can also be displayed at least in the vestibular or oral view, but preferably also in the occlusal view , for example in the form of areas that differ, preferably in terms of color, from the depiction of the teeth. Furthermore, a warning signal, for example a change in the color of these areas, can be displayed if an attempt is made to leave a range of permissible positions during the manual positioning of the attack elements.

Furthermore, at least one further selection area can be provided, which enables the selection of the type of attack element used. Not providing an attack element for a respective tooth can represent one of the selection options.

In the event that there should be a plurality of constellations according to which the attacking elements can be positioned without collision, a boundary condition can be specified on the basis of which it is decided which of the collision-free constellations is selected. This boundary condition can consist, for example, in arranging the engaging elements in such a way that the sum of the distances between the positions of the engaging elements and the FA point of the respective associated tooth is minimized. Another possible boundary condition could be to arrange the engagement elements as close as possible to the cutting edges or chewing surfaces of the teeth in order to increase the leverage of the wire arch and thus be able to reduce the treatment time.

In a development of the invention it is proposed that in addition to the occlusal view and the vestibular or oral view of the linear juxtaposition of the teeth, a perspective view of the actual position of the teeth and/or a perspective view of the target position of the teeth is also displayed. This perspective representation of the actual and/or the desired position of the teeth can preferably be a representation that can be rotated freely about all spatial axes.

It should also be added that when using an essentially planar archwire, after the end of the positioning of the attack elements, an image of the archwire can be printed out on a scale of 1:1. This printout can serve as a template for the treating dentist, which makes it easier for him to expand or narrow the archwire correctly.

Finally, it should also be added that the attacking elements can actually be attached to the tooth surfaces as is shown in FIG DE 10 2011 085 915 has been explained, ie with the help of a transmission mask.

• 1: eine schematische Darstellung des Gebisses eines Patienten, wie es der Kieferorthopäde zu Beginn der Behandlung vorfindet (Ist-Stellung der Zähne);
• 2: eine schematische Darstellung eines digitalen 3D-Modells der Ist-Stellung der Zähne;
• 3: eine schematische Darstellung eines digitalen 3D-Modells der Soll-Stellung der Zähne;
• 4: eine schematische Darstellung eines digitalen 3D-Modells der Soll-Stellung der Zähne einschließlich digitaler 3D-Modelle der Brackets;
• 5: eine schematische Darstellung eines digitalen 3D-Modells der Ist-Stellung der Zähne einschließlich digitaler 3D-Modelle der Brackets;

The invention will be explained in more detail below with reference to the drawing using an exemplary embodiment in which brackets are arranged as contact elements on the patient's teeth. It shows:

• 1 : a schematic representation of a patient's dentition as found by the orthodontist at the beginning of the treatment (actual position of the teeth);
• 2 : a schematic representation of a digital 3D model of the actual position of the teeth;
• 3 : a schematic representation of a digital 3D model of the desired position of the teeth;
• 4 : a schematic representation of a digital 3D model of the desired position of the teeth including digital 3D models of the brackets;
• 5 : a schematic representation of a digital 3D model of the actual position of the teeth including digital 3D models of the brackets;

With reference to the 1 until 5 First of all, the basic course of the preparatory work is to be explained which are required in order to design a dental apparatus which is to be permanently installed on a patient's teeth for the actual position of the patient's teeth.

In 1 shows the actual position of the teeth 12 of the dentition 10 of a patient whose nose and mouth are indicated only roughly schematically.

The first step in the process is to create a three-dimensional digital data model 14 (hereinafter: "digital 3D data model") of this actual position of the teeth 12 (see 2 ).

According to a first variant of the method, conventional techniques can be used for this purpose. For example, in a first sub-step, an impression of the actual position of the teeth 12 can be made in order to obtain a negative real model of the actual position of the teeth 12, and in a second sub-step this negative real model can be cast to create a positive real model of the actual position of the teeth 12 to get. In a third sub-step, this positive real model can then be scanned in order to obtain the desired digital 3D model 14 of the actual position of the teeth. Since these techniques are known per se, they will not be explained in more detail here.

According to an alternative method variant, however, it is also possible to create the digital 3D model 14 of the actual position of the teeth 12 directly by three-dimensional scanning of the patient's dentition 10, for example using a hand-held scanner.

The great advantage of the method according to the invention is that up to the insertion of the braces, including the attachment of the brackets to the patient's teeth 12, all further steps can be carried out without the patient having to be present, with the treating dentist carrying out a number of the tasks to be carried out further steps can be delegated to assistant staff. In particular, this reduces chair time and thus the costs incurred for the treatment.

In a second step, based on the digital 3D data model 14 of the actual position of the teeth 12 obtained in the first step, the treating dentist creates a digital 3D data model 16 of the target position of the patient's teeth 12, ie the tooth position as the treatment at the end of which is to be achieved (see 3 ). For this purpose, if necessary, each individual tooth 12 in the digital 3D model is moved translationally and/or rotationally, if necessary in all three spatial directions and/or around all three spatial axes, until it is positioned as desired.

Then, in a third step, the digital 3D data model of the target position of the teeth 12 is modified by arranging the brackets 22 virtually on the teeth 12 of the digital 3D data model. How this can be done with computer support is the subject of the present invention. The modified digital 3D data model of the target position of the teeth 12 is in 4 labeled 18.

Finally, in a fourth step, the modified digital 3D data model 18 of the target position of the teeth 12 is recalculated into a modified digital 3D data model 20 of the actual position of the teeth 12, which is 5 is shown. This backward calculation takes place in that the transformation movement carried out in the second step is reversed again for each individual tooth 12 . It is of particular importance that the brackets 22 are in the modified digital 3D data model 20 of the actual position of the teeth 12 at exactly the positions at which they have to be fastened on the patient's teeth 12 .

Based on the modified digital 3D data model 20 of the actual position of the teeth 12 can then be referred to in the DE 10 2011 085 915 described manner an auxiliary device for attaching the brackets are created on the teeth of the patient. In this regard be therefore on the description of DE 10 2011 085 915 referred.

The following is with reference to the 6 until 9b it will be explained how the step of determining the attachment positions of the brackets 22 on the patient's teeth 12 can be carried out with the aid of a computer.

First, the attending physician must select on the computer whether the dental apparatus is to be placed on the vestibular side or the oral side of the teeth 12 . A suitable starting position P0 on the associated teeth 12 must then be selected for each of the brackets 22 .

If the brackets 22 are arranged on the vestibular side, the FA points 24 on the tooth surfaces 12a of the teeth 12, for example, can be selected as the starting positions P0 for the brackets (see Fig 6 ). This selection can either be made by the doctor treating you on the computer or automatically specified by the computer. As a further aid, the computer can use the digital 3D data of the teeth 12 to determine a bracket setting surface 26 for each individual tooth. This bracket setting surface 26 can, for example, include all those connected points of the tooth surface 12a which are arranged around the FA point 24 and at which the curvature of the tooth surface 12a does not exceed a predetermined limit value. In this way, it can be ensured that no section of the attachment surface of the bracket 22 protrudes so far from the tooth surface 12a that the stability of the attachment of the bracket 22 to the tooth 12 would be jeopardized.

If one also takes into account that the brackets 22 can not only be displaced along the tooth surface 12a, but also that their distance from the tooth surface 12a can be changed, a permissible maximum distance from the tooth surface 12a can also be determined, so that from the two-dimensional bracket setting surface 26 becomes a three-dimensional bracket setting volume. Since only two-dimensional views of the bracket setting volume are shown both in the accompanying figures and in the display on a computer screen, both the three-dimensional bracket setting volume and the two-dimensional bracket setting surface 26 are often not precisely referred to as bracket setting area.

In order to make it easier for the attending physician to see the positioning of all brackets 22 at a glance, a so-called "panoramic view" of the patient's teeth 12 is displayed on the computer screen (see Fig 7 and 8th ). This panoramic view results from a linear juxtaposition of the teeth 12, in which the spaces between the teeth need not be shown to scale. The panoramic view preferably includes an occlusal view 30 of the teeth 12 and, when the dental apparatus is arranged on the vestibular side of the teeth 12, a vestibular view 32 ( 7 ) or if the dental apparatus is placed on the oral side of the teeth, an oral view 34 of the teeth 12 ( 8th ).

In 7 and 8th 1 is a panoramic view of both the teeth 12 of the maxilla 36 and the teeth 12 of the mandible 38 with the occlusal view 30 of the teeth 12 of the maxilla 36 above the vestibular 32 and oral views 34 of the teeth 12 of the maxilla 36 and the occlusal 30 view of the teeth 12 of the lower jaw 38 below the vestibular view 32 or oral view 34 of the teeth 12 of the lower jaw 38 are arranged. The brackets 22 and the bracket setting surfaces 26 are also shown.

The representation of the teeth 12 in the 7 and 8th is roughly in black and white. It goes without saying, however, that they can also be displayed in a representation simulating the real appearance of the teeth 12 and, if desired, also of the gums, whether in color or in shades of gray like a black-and-white photograph.

Next, a collision check is performed for the initial positions P0 of the brackets 22, i.e. the computer calculates whether there is a collision between the brackets 22 and one or more other elements, namely another bracket 22 and/or a tooth 12 and/or an arch wire 28. a collision occurs. If there is a collision for one of the brackets 22, this is displayed in the panorama view. For example, the relevant bracket 22 can be marked in color. For example, a bracket displayed in red can be easily recognized in a display of the teeth, possibly the gums, and the other brackets in gray tones. The strength of the collision can also be displayed, for example through the color intensity.

The collision check is preferably carried out both for the actual position and for the desired position of the teeth 12 . If there is no collision in either of the two positions, the certainty that there will be no collision in any intermediate position along the treatment path from the actual position to the desired position is relatively high. To be on the safe side, it can also be used for a or several intermediate positions, a collision check can be carried out.

If there is at least one collision, it is necessary in the further course of determining the attachment positions P of the brackets 22 on the teeth 12 to shift the brackets 22 within their respective bracket setting areas 26 with the aim of avoiding collisions. The options for relocation have already been described in detail at the beginning. This discussion is hereby referred to to avoid repetition.

The shifting of the brackets 22 can, for example, be carried out manually by the attending physician, i.e. interactively on the screen. For this purpose, each tooth 12 is assigned a plurality of buttons, namely the buttons 40 and 42 for the shift in the mesio-distal direction, the buttons 44 and 46 for the shift in the inciso-gingival direction and the buttons 48 and 50 for the shift from the Tooth surface 12a away or toward this. Each mouse click on one of these buttons causes the associated bracket 22 to be displaced in the respective direction by a predetermined distance. It is understood that the displacement of a bracket 22 in the mesio-distal direction is displayed simultaneously both in the occlusal view 30 and in the vestibular view 32 or the oral view 34 .

After each movement of a bracket 22, a collision check is carried out again and the result is displayed in the panorama view. In this way, the attending physician can immediately recognize the effects of his entries and correct them if necessary.

It should also be noted that the panoramic view according to 7 also includes additional buttons, namely buttons 52 and 54, by means of which all brackets 22, which are associated with the teeth 12 of one and the same jaw 36, 38, can be moved by the predetermined distance in the inciso-gingival direction. However, this button can also be omitted, since when one of the buttons 44, 46 for the inciso-gingival movement of a bracket 22 is clicked, the brackets 22 assigned to the other teeth 12 of the same jaw 36 or 38 are also moved by the predetermined distance to create a three-dimensional To avoid deformation of the archwire 28.

Buttons 56 and 58 are also provided for moving all of the brackets 22 away from and toward tooth surfaces 12a associated with teeth 12 of the same jaw 36 and 38, respectively.

In addition, it should be pointed out that with an oral arrangement of the dental apparatus, wire arches 28' of the so-called "mushroom type" (see 9a ) can be used. The step 28'a, which these wire arches 28' have, represents a further degree of freedom which, as in 8th shown, in the panoramic view results in the provision of further buttons 60 and 62, by means of which the height of the step 28'a between the individual wire arch sections 28'b and 28'c can be varied. In the case of using a 28” archwire of the “double mushroom type” (see 9b ) can also be sent to the in 8th additional buttons can be provided with 64 marked positions.

It should also be added that each tooth 12 can be assigned a further button and/or input area, not shown for the sake of clarity in the drawing, via which the attending physician can specify whether a tooth 12 is assigned a bracket 22 or not, and if so yes, which type of bracket 22 is assigned to tooth 12. In this way, if no positioning of the brackets 22 can be found within the predetermined bracket setting areas 26 for which there is no collision, at least one bracket 22 can be replaced by another type of bracket. Furthermore, no bracket 22 at all can be assigned to at least one tooth 12 . This at least one tooth 12 must then be subjected to a special treatment.

It should also be added that in the panorama view of the 7 and 8th Furthermore, the gum 66 can be shown, the gum edge 66a in 7 for only one tooth 12 is indicated by dashed lines. A further possibility of avoiding collisions consists in shifting the boundary of the bracket setting regions 26 on their gingival side below the gum line 66a, as has already been described above.

Finally, it should also be added that in addition to the panoramic view of the teeth 12, the digital 3D data models 18, 20 of the actual and target positions of the teeth 12, supplemented by the brackets 22, can also be displayed, as shown in FIGS 4 and 5 are shown. In this case, it is preferred if these representations can be rotated freely, so that they can be viewed from all desired directions.

Claims (16)

Computer-implemented method for determining the attachment positions (P) of a plurality of engagement elements (22) for an archwire (28) of a dental appliance ture on associated teeth (12) of at least one jaw (36, 38) of a patient, characterized in that on the one hand an occlusal view (30) and - when the dental apparatus is arranged on the vestibular side of the teeth (12 ) - on the other hand a vestibular view (32) or - when the dental apparatus is arranged on the oral side of the teeth (12) - on the other hand an oral view (34) of a linear juxtaposition of the teeth (12), in these views Furthermore, the attack elements (22) are shown. procedure after claim 1 , characterized in that the collision status of the contact elements (22) is also shown in the occlusal view (30) and the vestibular view (32) or the oral view (34). procedure after claim 1 or 2 , characterized in that the gums (66) are also shown in the occlusal view (30) and the vestibular view (32) or the oral view (34). Procedure according to one of Claims 1 until 3 , characterized in that the teeth (12) and/or the engaging elements (22) and/or the gum (66) in a manner based on the three-dimensional digital data model (16) of the target position, the appearance of the real teeth (12) simulated representation are displayed. Procedure according to one of Claims 1 until 4 , characterized in that the occlusal view (30) when displaying the target position of the teeth (12) of the upper jaw (36) above the vestibular view (32) or the oral view (34) and when displaying the target position of the Teeth (12) of the lower jaw (38) is displayed below the vestibular view (32) or the oral view (34). Procedure according to one of Claims 1 until 5 , characterized in that the vestibular view (32) or the oral view (34) of the teeth (12) of the upper jaw (36) above the vestibular view (32) or the oral view (34) of the teeth (12) of the lower jaw (38) is displayed. Procedure according to one of Claims 1 until 6 , characterized in that the occlusal and vestibular or oral views (30, 32, 34) have selection areas (40, 42, 44, 46, 48, 50) for selecting the tooth or/and the type of movement or/and the direction of movement or/ and the amount associated with the movement. Procedure according to one of Claims 1 until 7 , characterized in that a separate selection area (40, 42, 44, 46, 48, 50) is provided for each direction of movement of each type of movement of each tooth (12), which can be selected by means of a pointer input device of the computer. procedure after claim 7 or 8th , characterized in that at least one further selection surface (52, 54, 56, 58) is provided, which is assigned to a group of teeth comprising a plurality of teeth (12). Procedure according to one of Claims 7 until 9 , characterized in that after each selection event the collision status of the attacking elements (22) corresponding to the new positions of the attacking elements (22) is calculated. Procedure according to one of Claims 1 until 10 , characterized in that the display of the positions (P) of the attacking elements (22), preferably also their collision status, is updated synchronously for both displays (30 and 32 or 34) after each selection event. Procedure according to one of Claims 1 until 11 , characterized in that at least in the vestibular view (32) or the oral view (34), the ranges (26) of permissible positions (P) for arranging a respective engagement element (22) are displayed, for example in the form of surfaces that differ, preferably in color, from the representation of the teeth (12). Procedure according to one of Claims 7 until 12 , characterized in that at least one further selection area is provided, which allows the selection of the type of engagement element (22) used. Procedure according to one of Claims 1 until 13 , characterized in that in the event that there is a plurality of constellations, according to which the attack elements (22) are collision-free positionable, one of the collision-free constellations is selected on the basis of a predetermined boundary condition. Procedure according to one of Claims 1 until 14 , characterized in that in addition to the occlusal view (30) and the vestibular view (32) or oral view (34) of the linear juxtaposition of the teeth (12) there is also a perspective view of the actual position (14) of the teeth (12) or/and a perspective view of the desired position (16) of the teeth (12) is displayed. Procedure according to one of Claims 1 until 15 , characterized in that when using a substantially planar archwire (28) after the end of the positioning of the engagement elements (22), an image of the archwire (28) is printed out on a scale of 1:1.

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