FR3136957A1 - METHOD FOR DETERMINING AN ORTHODONTIC TREATMENT PLAN - Google Patents

Abstract

Method of entering information into a computer, said method comprising the following steps: 01) the user enters a first piece of information on the computer; 02) the computer analyzes said first piece of information, then prepares and displays it on the screen of the computer, a form page comprising an input field, presenting a request to the user to enter a second piece of information, whether the input field is displayed or not and/or the nature of the second information accepted by the input field depending on the first information entered by the user in the previous step;03) the user enters the second information on the computer by means of the input field;04) the computer uses the second information and preferably the first information to define an orthodontic treatment plan and/or to monitor the proper progress of orthodontic treatment. No abstract figure

Description

METHOD FOR DETERMINING AN ORTHODONTIC TREATMENT PLAN

The present invention relates to a method of determining an orthodontic treatment plan, which includes determining a complete orthodontic treatment plan or part of a complete orthodontic treatment plan.

The invention also relates to a computer program as well as a computer and a system for implementing this method.

Orthodontic treatment is intended to modify the arrangement of a user's teeth using orthodontic appliances.

Among orthodontic appliances, we distinguish orthodontic appliances with arch wires and brackets on the one hand, and orthodontic aligners on the other hand.

An orthodontic appliance with arch and brackets comprises brackets, or “brackets” , fixed to the teeth and connected together by means of an arch, conventionally made of a shape memory material. It exerts a rapid action on the movement of the teeth of the treated user.

A gutter, “align” in English, is classically presented in the form of a removable one-piece device, conventionally made of a transparent polymer material. It has a channel shaped so that several teeth of an arch, generally all the teeth of an arch, can be accommodated there. The shape of the channel is adapted to hold the channel in position on the teeth, while performing a corrective action on the positioning of certain teeth. An orthodontic splint has a slower initial action than an archwire and bracket brace. Advantageously, the gutter can however be replaced by the user himself. Additionally, gutters are more discreet than arch and tie devices.

Implementing orthodontic treatment requires the prior preparation of an orthodontic treatment plan in order to plan the steps of the upcoming orthodontic treatment. The orthodontic treatment plan thus defines times at which a check of the dental arch by a dental practitioner and/or a modification of an orthodontic appliance, for example a change of orthodontic appliance, for example an orthodontic splint, and/or a change of orthodontic arch wire, and/or fabrication of an orthodontic appliance is/are planned.

Classically, an orthodontic treatment plan is created by the dental practitioner with a computer. The computer allows him in particular to visualize a model of a dental arch and to modify this model to determine a possible evolution of the position and orientation of each tooth, compatible with the evolution of the position and the orientation of the other teeth, until reaching the desired arrangement for all the teeth in the arch. The dental practitioner thus succeeds in determining a series of digital three-dimensional models comprising a model representing said arch at the start of orthodontic treatment, a model representing said arch at the end of orthodontic treatment, and one or more "intermediate" models representing said arch at different times. intermediate times between the start and the end of the orthodontic treatment, the intermediate times being times at which a check of the arch by the dental practitioner and/or a modification of an orthodontic appliance and/or a manufacturing of an orthodontic appliance is /are planned. This series of models, or “deformation scenario”, and the intermediate moments thus define the orthodontic treatment plan.

Software for manipulating the arch model and generating an orthodontic treatment plan is well known. However, they require learning how the software works and require orthodontic skills. Creating an orthodontic treatment plan can be laborious and time-consuming.

Furthermore, this software can lead to orthodontic treatment plans leading to rapid tooth movements, potentially detrimental to the user's health.

There is an ongoing need for a method and system to improve the execution of an orthodontic treatment plan.

One aim of the invention is to meet this need.

According to a first main aspect,the invention provides a method for generating an orthodontic treatment plan for a user's dental arch, the method comprising the following successive steps:
a) generation or recovery of an “initial” model representing in three dimensions said dental arch at an initial instant, said initial model being divided into tooth models, and optionally a model of the gum, and
generation or recovery of a “final” model representing said dental arch with a “final” arrangement of the tooth models as desired at the end of the orthodontic treatment;
b) determination, by a computer, of a set of successive elementary deformations transforming, by moving the tooth models, the initial model into a final model, said elementary deformations each respecting a respective set of constraints, the models resulting from the successive elementary deformations being called “transition models”, the succession of all the successive transition models being called “basic deformation scenario”;
c) determination, by the computer,
- a duration, called “treatment duration”, to carry out, from the initial moment, the deformation of the dental arch following the basic deformation scenario until the final arrangement is obtained, at a moment final; And
- intermediate times between the initial and final times to carry out the deformation of the dental arch according to the basic deformation scenario, the intermediate times being times at which a check of the arch by a dental practitioner and/or a modification of an orthodontic appliance and/or the manufacture of an orthodontic appliance is/are planned,
the basic deformation scenario and said intermediate moments defining said orthodontic treatment plan, called “basic orthodontic treatment plan”.

The times at which it is expected, following the basic orthodontic treatment plan, that the dental arch will present a shape according to the transition models are called “transition times”.

As will be seen in more detail later in the description, the computer therefore creates, from the initial and final models alone, the basic orthodontic treatment plan quickly and automatically, that is to say without human intervention. The automation of the creation of orthodontic treatment plans can be advantageously optimized, in particular with metaheuristic methods, which makes it possible to achieve performances that are very difficult to achieve manually, in particular by avoiding collisions or ensuring tooth movements as regular as possible, or as quickly as possible.

Preferably, a method according to the first main aspect of the invention also has one or more of the following optional characteristics:
- in step a), said computer determines the final model from the initial model;
- in step a), to determine the final model, said computer
- analyzes the shape of the initial model so as to determine the curvature and length of the dental arch and define a base line having said curvature and said length, then,
- for each of a plurality of tooth models, preferably for each tooth model of the initial model, determines a position and an orientation of said tooth model relative to said baseline, preferably from predefined rules and/ or by assimilating the user's dental arch to a historical dental arch similar to the user's dental arch;
- preferably, prior to step a), said predefined rules are determined by statistical processing of historical data;
- in step b), said set of constraints includes prescription constraints imposed by the user, preferably to specify the relative importance that the user gives to the speed of the orthodontic treatment, and/or to the pain generated by orthodontic treatment, and/or comfort during orthodontic treatment, and/or cost of orthodontic treatment and/or aesthetic impact of orthodontic treatment and/or reliability of orthodontic treatment, i.e. say the probability that the orthodontic treatment will lead to the expected result, and/or a duration for wearing an orthodontic appliance, and/or a predetermined functional, orthodontic or therapeutic objective;
- in step b), the computer displays a dynamic form adapted to the entry, preferably by the user, of at least part of the information necessary for the definition of said set of constraints, in particular necessary for the definition prescription constraints;
- in step b), said set of constraints authorizes limited penetration of a tooth model into an adjacent tooth model, the limitation of said penetration preferably being determined by the possibility, preferably evaluated according to the rules of orthodontics, preferably by a dental practitioner, to file, during orthodontic treatment, at least one of the teeth modeled by said tooth models, in order to avoid a collision between said teeth resulting from said penetration;
- in step b), the computer implements an optimization algorithm, preferably a first optimization algorithm to determine a basic deformation scenario leading to a model as close as possible to the final model and/or a second optimization algorithm to determine a basic deformation scenario that best meets one or more prescriptions dictated by the user;
- in step b), the computer
- searches for a “coarse” deformation scenario with a rough initial model comprising less than 5000 points, preferably less than 2000 points, preferably less than 1000 points, preferably less than 500 points, preferably less than 100 points, and/ or more than 50 points, the initial coarse model resulting from a simplification of a fine initial model comprising more points than the initial coarse model, preferably comprising 1.1, or 1.5 or 2 or 5 or 10 or 100 times more points than the initial rough model, then
- completes, at least partially, the transition and final models, that is to say adds points to these models,
- determines whether, in the gross deformation scenario in which the transition and final models have been thus completed, tooth models collide unacceptablely, and,
in case of unacceptable collision, adds points to the initial rough model, preferably at least in the collision zones, preferably at least the points added to the transition and final models in the collision zones, or even with all the points added to the transitional and final models, and
- resumes said search with the initial rough model to which the points have been added, the cycling being preferably continued until a deformation scenario free of unacceptable collision is obtained, constituting the basic deformation scenario;
- at the start of step c), the computer
- determines, for each tooth model, the instant closest to the initial instant at which the tooth model can reach, following the basic deformation scenario determined in step b), its configuration in the final model , or “moment of end of journey”;
- determines, among all the tooth models, a tooth model having the end of path time furthest from the initial time, or “limiting tooth model”;
- sets the final instant as being the end instant of the path of the limiting tooth model;
- the computer preferably determines the end instant of movement of a tooth model, preferably of each tooth model, by dividing a distance representative of the movement of the tooth model during the basic deformation scenario, by a speed representative of the kinetic capacities of said tooth model;
- in step c), the computer determines the intermediate moments by dividing said treatment duration according to the capacity of one or more orthodontic appliances, preferably according to the capacity of orthodontic aligners, to move the modeled teeth by the tooth models, and/or by dividing said treatment duration into intervals of the same duration, each interval preferably corresponding to a duration of use of an orthodontic splint by the user intended for orthodontic treatment, or corresponding to a frequency for monitoring the proper progress of the orthodontic treatment, said frequency preferably being predetermined;
- the process comprises, after step c), the following first step d):
d) determination, by the computer, of a new deformation scenario, called “first smoothed deformation scenario”,
- in which the configuration of the limiting tooth model is, at any intermediate instant, preferably at any transition instant, that defined by the basic deformation scenario determined in step b), and
- in which a movement speed, preferably each movement speed, of at least one tooth model other than the limiting tooth model, or “slowed down tooth model”, is smoothed between the initial instant and the instant final, that is to say in which at least one speed parameter is reduced or optimized, preferably minimized,
the first smoothed deformation scenario and said intermediate moments defining a new orthodontic treatment plan, called “first smoothed orthodontic treatment plan”;
- the speed parameter is chosen from:
- the greatest value of a movement speed of said slowed tooth model reached between the initial instant and the final instant, and/or
- the difference between said largest value of said movement speed and the smallest value of said movement speed of said slowed tooth model between the initial instant and the final instant, and/or
- the variation of said speed of movement of said slowed tooth model, on average between the initial instant and the final instant;
- the first smoothed deformation scenario is determined so that the greatest value of said movement speed between the initial instant and the final instant is less than the greatest value of said movement speed between the initial instant and the final instant final instant in the basic deformation scenario determined in step b);
- the method comprises, after said first step d), one or more successive additional steps d), each additional step d) comprising the determination, by the computer, of an additional smoothed deformation scenario in which
- the limiting tooth model follows the path defined by the basic deformation scenario determined in step b), and
- the tooth model(s) slowed down from the step(s) d) prior to said additional step(s) follow the path(s) defined by the said smoothed deformation scenario(s) determined (s) in said previous step d) or in said previous steps d), respectively,
the additional smoothed deformation scenario being determined to reduce or optimize, preferably minimize said at least one speed parameter for at least one “additional” slowed tooth model different from the slowed tooth model(s) of the step(s) d) prior, respectively, between the initial instant and the final instant,
the orthodontic treatment plan thus modified being called “additional smoothed orthodontic treatment plan”;
- the tooth model slowed down during the first step d) or during an additional step d) is chosen according to a criterion of usefulness for the dental practitioner and/or the user, preferably according to the risk what does the application of the basic deformation scenario or the smoothed orthodontic treatment plan of step d) represent for the health of the user, respectively;
- the usefulness criterion defines a usefulness for limiting a risk to the user's health and/or for meeting the user's requirements;
- the tooth model slowed down during the first step d) or during an additional step d) is chosen according to the risk represented, for the health of the user, by the application of a high speed of movement, and in particular the application of a movement speed corresponding to the highest physiologically acceptable movement speed for the slowed tooth that it is modeling;
- the closer an additional step d) is to step c), the higher said risk is, that is to say that the computer proceeds as a priority to smoothing the movement speeds of the models of the teeth for which a movement rapid induces the highest risk;
- preferably, the method comprises a step d) for each tooth model, except the limiting tooth model;
- the method comprises, after step c) and, optionally after step d) or the additional step(s) d), the following step e):
e) design and manufacture of at least one orthodontic appliance according to the basic orthodontic treatment plan obtained at the end of step c) or according to the smoothed orthodontic treatment plan obtained at the end of step d) or a cycle of steps d);
- said orthodontic appliance is an orthodontic splint and the intermediate times are exclusively times at which a change of orthodontic splint is planned;
- said orthodontic appliance is an orthodontic arch and/or an auxiliary appliance and the intermediate times are exclusively times at which a change of orthodontic arch and/or auxiliary appliance is planned;
- said auxiliary device is chosen from a hook, a button, a cleat, an elastomeric chain, a spring, an elastic band and a mini-screw;
- said orthodontic appliance is an assembly comprising an orthodontic arch and fasteners for fixing said orthodontic arch on the teeth (“brackets” in English) and the intermediate moments are exclusively moments at which a change of the arch and/or a or several fasteners are provided;
- the computer presents the basic orthodontic treatment plan and/or the smoothed orthodontic treatment plan to a dental practitioner, for validation.

Complete orthodontic treatment typically involves several phases. Each phase, or “partial orthodontic treatment”, can be the subject of an orthodontic treatment plan following a method according to the invention, the initial model representing the dental arch at the start of the phase considered and the final model representing said dental arch with an arrangement of the tooth models as desired at the end of said phase.

The invention thus also relates to a method for generating a plan for a complete orthodontic treatment of a dental arch of a user, the complete orthodontic treatment consisting of a succession of several partial orthodontic treatments each corresponding to a phase respective of the complete orthodontic treatment, the process comprising the following successive steps:
A') generation or recovery of a first “start of phase” model representing said dental arch at a time at the start of the first phase of the complete orthodontic treatment, said first model being divided into tooth models, and
generation or recovery of a last “end of phase” model representing said dental arch with a desired arrangement of tooth models at the end of the last phase of the complete orthodontic treatment, that is to say the end of the complete orthodontic treatment;
B') determination, preferably by a computer or by a computer-assisted dental practitioner, for each phase, from the first phase to the penultimate phase, of a respective end-of-phase model representing said dental arch with a desired arrangement of tooth models at the end of said phase;
C') for each phase, implementation of a process comprising steps a) to c), and preferably a step d), preferably a cycle of steps d), the initial model being the start model of said phase and the final model being the end model of said phase.

The method implemented in step C’) may include one or more of the optional characteristics described in this description.

The process of smoothing the speeds of tooth models mentioned above can be generalized.

According to a second main aspect,the invention thus relates to a method for generating a plan for a partial or complete orthodontic treatment of a user's dental arch, the method comprising the following successive steps:
A) preferably following step a),
- generation or recovery of an “initial” model representing in three dimensions said dental arch at an initial instant, said initial model being divided into tooth models, and
- generation or recovery of a “final” model representing in three dimensions said dental arch with a “final” arrangement of the tooth models as desired at a final moment marking the end of the orthodontic treatment, partial or complete;
B) for each tooth model,
- determination of a distance measuring a difference between the configurations of the tooth model in the initial model and in the final model;
- determination of the shortest possible duration for the tooth model to travel said distance, that is to say determination of the shortest movement duration to transit from the configuration of said tooth model in the initial model to the configuration of said tooth model in the final model, or “minimum travel time”;
C) identification of the tooth model which presents said longest minimum displacement duration, or “limiting tooth model”;
D) determination of a “first smoothed deformation scenario” according to which the initial model is transformed into a final model by moving the tooth models, the first smoothed deformation scenario being determined so as to minimize, for at least a first model of “idle” tooth different from the limiting tooth model, a speed parameter chosen from:
- the greatest value of a movement speed of said slowed tooth model reached between the initial instant and the final instant, and/or
- a speed representative of the speed of movement of said slowed tooth model, preferably an average speed between the initial instant and the final instant, and/or
- the difference between said largest value of said movement speed and the smallest value of said movement speed of said slowed tooth model between the initial instant and the final instant, and/or
- the variation of said speed of movement of said slowed tooth model, on average between the initial instant and the final instant.

Preferably, intermediate instants are determined, preferably the computer determines, preferably marking instants at which orthodontic splint changes are planned, the first smoothed deformation scenario and said intermediate instants defining a first smoothed orthodontic treatment plan.

The generation of the final model can be carried out, from the initial model, by a dental practitioner using a computer adapted to the manipulation of tooth models.

In one embodiment, the determination of the distance measuring a difference between the configurations of the tooth model in the initial model and in the final model is carried out without the need to have previously determined the arrangements of the teeth between the models initial and final, for example by comparing the initial and final models.

Preferably, however, in step B), a “basic deformation scenario” of said arch is determined, preferably a computer determines, the basic deformation scenario comprising a succession of intermediate models modeling said arch in three dimensions. intermediate instants between the initial instant and the final instant, the determination of said distance being a function of said basic deformation scenario, the distance being for example the distance traveled by one or more points of the tooth model following the scenario of basic deformation; Then
in step C), we determine, preferably a computer determines the limiting tooth model as the tooth model having, following the basic deformation scenario, the last one reaching its configuration in the final model.

The basic deformation scenario and the intermediate moments form a “basic orthodontic treatment plan”.

Smoothing can be carried out without necessarily having to define a base deformation scenario, but the prior generation of a base deformation scenario considerably improves the reliability or "predictability" of the orthodontic treatment plan, i.e. increases the likelihood that teeth will shift following the orthodontic treatment plan.

In one embodiment, to determine the base deformation scenario, the computer
- determines a set of successive elementary deformations transforming, by moving the tooth models, the initial model into the final model, said elementary deformations each respecting a respective set of constraints,
- determines, for each tooth model, said distance as a function of said set of elementary deformations, said distance preferably being the accumulation of the elementary distances traveled by a point or a plurality of points of the tooth model during the elementary deformations.

The basic deformation scenario and/or movement speeds of the tooth models can be determined by a dental practitioner using a computer suitable for handling the tooth models, for example by means of the software Treat described on the page https://en.wikipedia.org/wiki/Clear_aligners#cite_note-invisalignsystem-10.

The basic deformation scenario can alternatively be determined following step b).

Travel speeds can be calculated from
- distances measured by comparison of the initial and final models and/or distances determined from the basic deformation scenario, preferably determined following step b), and
- time intervals determined from the treatment duration, preferably determined following step c).

The first smoothed deformation scenario preferably results from a modification of a basic deformation scenario. Such a method can advantageously be used to smooth a classically defined basic orthodontic treatment plan, in particular with a view to orthodontic treatment with a set of orthodontic aligners. Indeed, such a plan is conventionally defined manually by the dental practitioner, using a computer, by manipulating the tooth models from an initial model to the final model.

The dental practitioner can also use software, for example Treat , capable of providing transition models and intermediate models. The dental practitioner can then modify these models, with the software recalculating the intermediate times accordingly.

The smoothing can alternatively relate to a basic deformation scenario determined by a computer, independently, as described according to the first main aspect of the invention.

Smoothing can be carried out by the computer, independently.

Preferably, the first tooth slowed down is, among all the teeth modeled in the initial model and apart from the limiting tooth modeled by the limiting tooth model, the tooth of the arch which it would be most useful to slow down, following a usefulness criterion defined by the dental practitioner and/or the user and with regard to the basic orthodontic treatment plan.

The first tooth slowed may be the tooth whose moving speed is most critical to the user's health

The first slowed tooth may for example be the tooth whose movement speed, following the basic orthodontic treatment plan, reaches a value closest to a predetermined “acceptable” value, in particular a value beyond which presents an unacceptable risk to the health of the user.

Preferably, a method according to the second main aspect of the invention also has one or more of the following optional characteristics:
- the intermediate times, preferably determined by the computer, are times at which a check of the arch by a dental practitioner and/or a modification of an orthodontic appliance and/or a manufacturing of an orthodontic appliance is/are planned €(s), preferably times when a change of orthodontic splint is planned;
- the first slowed tooth is, among all the teeth modeled in the initial model and apart from the limiting tooth modeled by the limiting tooth model, the tooth in the arch whose speed of movement is the most critical for the health of the tooth the user, for example the tooth whose rapid movement generates the highest risk for the user;
- the method comprises, after determining the first smoothed deformation scenario, the determination, preferably by a computer, of a second smoothed deformation scenario reducing, preferably minimizing the speed parameter for a second slowed tooth model, modeling a second slowed tooth, different from the limiting tooth model and the first slowed tooth model, preferably reducing, preferably minimizing the greatest value of the speed of movement reached between the initial instant and the final instant by said second model of slowed tooth, with the constraint that the limiting tooth model and the first slowed tooth model follow the paths defined by the first smoothed deformation scenario;
- preferably, the second slowed tooth is, among all the teeth modeled in the initial model and apart from the limiting tooth and the first slowed tooth, the tooth of the arch which it would be most useful to slow down, according to said utility criterion defined by the dental practitioner and/or the user and with regard to the first smoothed orthodontic treatment plan, preferably the tooth which leads to the lowest risk for the health of the user, said utility criterion preferably being identical to the utility criterion used to choose the first slowed tooth;
- the second slowed tooth is the tooth whose movement speed, following the first smoothed orthodontic treatment plan, reaches a value closest to a predetermined “acceptable” value, and in particular to a critical value for the health of the user ;
- the first smoothed deformation scenario, and optionally the second smoothed deformation scenario, is/are determined so as to respect:
- anatomical constraints preferably imposing an absence of penetration of a tooth model into an adjacent tooth model, and/or that the positions of one or more points of a tooth model are contained in a defined envelope around the tooth model, and/or that the translation speed of a tooth model in one direction and in one direction is less than an upper limit for a translation speed, and/or that the rotation speed of a tooth model tooth around an axis and in one direction is less than a high limit for a rotation speed; and or
- clinical constraints imposed by the rules of orthodontics and/or the dental practitioner, preferably imposing immobility of one or more tooth models, and/or imposing technical constraints to be respected in order to move a tooth model, and /or favoring movements relative to others, and/or imposing an order for moving the tooth models, and/or imposing a correct occlusion, and/or authorizing or prohibiting filing of the teeth, i.e. say authorizing or prohibiting penetration of a tooth model into an adjacent tooth model, and/or authorizing limited filing of the teeth, i.e. limiting the degree of penetration of a tooth model into a model adjacent tooth, and/or authorizing or prohibiting extraction of one or more teeth, and/or imposing a speed of movement of one or more teeth; and or
- prescription constraints imposed by the user due for example to a need for orthodontic treatment generating limited pain and/or having a limited duration and/or having a limited cost, and/or having a limited aesthetic impact and /or having minimal reliability, and/or involving a limited duration for wearing an orthodontic appliance, in particular a maximum duration for wearing an orthodontic splint or an arch appliance and brackets, and/or having a limited number of steps, and in particular limiting the number of orthodontic aligners necessary for the orthodontic treatment associated with the first smoothed deformation scenario, or optionally with the second smoothed deformation scenario, and/or having a predetermined number of steps, and/ or authorizing or prohibiting tooth filing, and/or authorizing limited tooth filing, and/or authorizing or prohibiting extraction of one or more teeth, and/or authorizing or prohibiting the use of one or more orthodontic appliances auxiliaries.

In general, the method preferably comprises the determination, preferably by a computer, successively for each of the tooth models considered as "slowed-down tooth model", apart from the limiting tooth model, a smoothed deformation scenario (first scenario of smoothed deformation for the first slowed tooth, second smoothed deformation scenario for the second slowed tooth, etc.), each time with the constraint that the limiting tooth model and the slowed tooth models following the previously defined smoothed deformation scenarios follow the paths defined by said previous smoothed deformation scenarios.

According to a third main aspect, the invention relates to a method of entering information into a computer, in particular as part of a method of generating a plan for an orthodontic treatment of a dental arch, preferably according to the first or second main aspect of the invention, preferably at least for entering prescription constraints, said entry method comprising the following steps:
01) a first user enters a first piece of information into the computer, for example in a first input field of a first form page displayed on a first screen of the computer;
02) the computer analyzes said first information, then prepares and displays, on a second screen of the computer, a second form page comprising a second input field presenting a request to a second user to enter second information , the display or not of the second input field and/or the nature of the second information accepted by the second input field depending on the first information entered by the first user in the previous step;
03) the second user enters the second information on the computer using the second input field,
04) preferably, the computer uses the second information and preferably the first information to define an orthodontic treatment plan and/or to monitor the proper progress of an orthodontic treatment.

The second form page, used for entering the second information, may be a new page or result from an adaptation of the first page used in step 01) to enter the first information.

According to the invention, it belongs to a dynamic form.

As will be seen in more detail later in the description, a dynamic form comprising one or more said pages advantageously allows much more efficient entry than entry with a static form. It avoids laborious reading of input pages unsuitable for the second user. A dynamic form therefore speeds up entry by the second user. By making the situation easier to understand, it also limits the risk of incorrect entries.

A dynamic form closely guides the entry, which advantageously allows entry without assistance, and in particular without the dental practitioner. The entry can in particular be carried out remotely from the dental practitioner, and in particular with the mobile telephone of the first and/or second user. For example, if several photos must be acquired under different acquisition conditions, the form can request the entry of the first photo and only request the entry of the second photo after having analyzed the first photo and validated it.

The dynamic form is particularly useful when the computer is integrated into a mobile phone. It actually limits the exchange of information with the mobile phone.

The second form page may come from a refresh of the first form page, or be a new form page, in particular when the first form page does not belong to the same form as the second form page, for example example when the first form page was displayed more than 1 hour before the second form page.

The first user may be identical to the second user, and in particular be an individual for whom orthodontic treatment is in progress or to be planned. The first and second screens are then preferably identical. They can be, for example, the screen of the user's mobile phone.

The first user may be different from the second user. In particular, the first user may be a dental practitioner and the second user may be an individual for whom orthodontic treatment is in progress or to be planned. The first and second screens are then preferably different. They can be for example the screen of a PC at the dental practitioner and the screen of the user's mobile phone, respectively. This embodiment advantageously allows the first user to enter “professional” information, which the second user is unable to determine alone. For example, a dental practitioner can analyze the dental situation of the individual, for example by analyzing photos of the individual's mouth that the latter has sent to him with his telephone, and enter data characterizing this dental situation. The individual then has access to a form specifically adapted to their dental situation. More generally, this embodiment allows each user to enter information that the other user does not know, the input interface for a user depending on the inputs made by the other user.

In one embodiment, the first information and/or the second information defines a number of teeth to be moved and/or the number of teeth to be moved and/or kept immobile as part of a treatment plan orthodontics.

Preferably, a method according to the third main aspect of the invention also has one or more of the following optional characteristics:
- the second input field only accepts second information if it meets a criterion, for example only if it belongs to a predefined range or to a predefined list, said criterion depending on the first information;
- the format of the second input field depends on the first information;
- the first information comprises at least one photo, preferably at least one closed mouth photo and at least one photo and/or at least one panoramic and/or cephalometric radiograph, open mouth, preferably at least one closed mouth photo, at least an open mouth photo, at least one front view photo, at least one right view photo and at least one left view photo, the right and the left being relative to the first user;
- the computer analyzes said photo or photos and, depending on the result of said analysis, displays or not the second input field and/or determines the nature of the second information accepted by the second input field;
- as soon as the first information has been entered by the first user, the computer analyzes said first information and adapts the displayed page accordingly;
- the entry of the first information precedes the display of the second form page by less than 10 minutes;
- the first information and/or the second information are a prescription imposed by the first and/or second user expressing a need so that an orthodontic treatment to be planned generates limited pain and/or has a limited duration and/or has a cost limited, and/or has a limited aesthetic impact and/or has minimal reliability, and/or involves a limited duration for wearing an orthodontic appliance, and/or achieves a predetermined functional, orthodontic or therapeutic objective, in particular for define constraints for generating an orthodontic treatment plan according to the first and/or second main aspects of the invention.

Preferably, only the input fields for which an entry is necessary are displayed. That is, if an entry is not always necessary, the computer queries the first user to determine whether the corresponding entry field should be displayed.

For example, if the possibility of benefiting from anesthesia depends on the medical history of the second user, before displaying a second input field for the second user to enter their agreement or disagreement for anesthesia, the computer can display input fields for the first user to specify whether the second user has already had reactions to anesthesia, and only in the event of a negative response, display a second input field for the second user to enter their agreement or disagreement for anesthesia .

In addition to one or more input fields, a form page typically includes navigation buttons allowing you to display the previous page or the next page of the form, or to exit the form.

The first information and/or the second information may be of any nature, and in particular be photos of said dental arch, pictures acquired by X-ray radiography of said dental arch, data on an orthodontic treatment envisaged or in courses, models of said dental arch or views of models of said dental arch, or clinical prescriptions.

The first information and/or the second information may include information about the first and/or second user, for example data on the age or gender of the first user.

Preferably, it(s) comprise(s) photos, preferably extraoral, of at least one arch of the first user, preferably in the form of a film. Preferably, the photos include at least one open mouth photo, and at least one open mouth photo. Preferably, the photos include at least one front view photo, one right view photo and one left view photo, the right and left being relative to the user.

Preferably, the first information and/or the second information comprise(s) a clinical prescription defining a number of teeth to be moved and the number of teeth to be moved and/or kept immobile.

Preferably, the first information and/or the second information comprise(s) a definition of treatment objectives and/or a definition of a maximum number of orthodontic aligners for an orthodontic treatment to be planned.

The computer preferably includes a memory defining a set of conditional rules determining the second input field, directly or indirectly depending on the first information.

A conditional rule determining the second input field of the second information directly as a function of the first information is for example "if the first user has entered an age less than 12 years, display the second input field asking if the first user has lost her baby teeth.

Conditional rules determining the second input field indirectly as a function of the first information are for example "if the analysis of a photo of a dental arch of the first user reveals the presence of tartar, display the second input field requesting the date on which the first user underwent scaling. The photo constituting the first information needs to be analyzed in order to determine the presence of tartar. The second input field is only displayed if the analysis leads to tartar detection.

Preferably, the conditional rules also determine the presentation of the second input field, and more generally of the objects on the page comprising the second input field. For example, the presentation may be different depending on the age of the first user.

Conditional rules can be ordered in the form of a decision tree.

In one embodiment, the method comprises, for each first piece of information in a set of first pieces of information, a cycle of steps 01) to 03), said set of first pieces of information preferably comprising more than 10, more than 50, more of 100 and/or less than 1000 first pieces of information, the display or not of the input field of a step 02) of a said cycle and/or the nature of the second piece of information accepted by the input field of a step 02) of a said cycle depending not only on the first information entered by the user in step 01) of said cycle, but also on at least one first piece of information and/or at least one second piece of information entered ) during one or more previous cycles.

The process preferably comprises a single step 04).

The shape of the second input field is not limited.

To the extent that a feature according to one aspect of the invention is technically compatible with another main aspect of the invention, it can be applied to this other aspect of the invention.

In particular, the characteristics relating to smoothing described according to the first main aspect of the invention are potentially applicable to the second main aspect, and vice versa. In particular, some terms, such as "base deformation scenario" or "first smoothed deformation scenario" are used in the description of the two main aspects because they refer to similar objects, and possibly to the same objects when both main aspects apply. For these objects in particular, the characteristics according to the first main aspect of the invention are potentially applicable to the second main aspect, and vice versa.

The invention also relates to:
- a computer program including program code instructions for execution
- steps b) and c), preferably steps a), b) and c), and optionally the first step d) and preferably additional steps d), and preferably a design operation an orthodontic appliance for step e) and/or
- a step C') and preferably a step A') or B'), preferably a step A') and a step B') and a step C'), and /Or
- a step 02), that is to say for the display of a dynamic form according to the invention, and preferably an entry of the first information, and/or
- steps B), C) and D), and preferably A),
when said program is executed by said computer;
- a computer medium on which such a program is recorded, for example a memory or a CD-ROM, and
- a computer in which such a program is loaded,
- an assembly comprising a said computer and an apparatus for manufacturing an orthodontic appliance for the implementation of step e).

Preferably, the computer program includes program code instructions to automate any operations that can be automated.

Preferably, the computer program further includes program code instructions for cutting the initial model into tooth models and/or determining the final model from the initial model.

The invention also relates to a system comprising
- a three-dimensional scanner capable of producing a “raw” model of the arch of the first user, and
- a computer according to the invention, preferably optionally configured to transform said raw model into an initial model, optionally with the assistance of a dental practitioner.

Definitions

By “ user ” is meant any person for whom a method according to the invention is implemented, whether this person is sick or not.

By “dental practitioner”, we mean any dental practitioner in the broad sense, which includes in particular orthodontists and dentists.

A “ complete orthodontic treatment ” is a treatment intended to correct the arrangement of the teeth in a dental arch to a final position desired by the user. Orthodontic treatment that is part of a complete orthodontic treatment is called “partial”. Without specification, “orthodontic treatment” generically refers to complete or partial orthodontic treatment.

Orthodontic treatment requires the use of one or more orthodontic appliances. A retention treatment intended to maintain the teeth in a definitive position is not considered here as orthodontic treatment.

Orthodontic treatment is planned with a “ treatment plan ”. We thus distinguish between “orthodontic treatment” which designates a series of operations which take place in reality and the “treatment plan”, which is the result of the design of the orthodontic treatment. The treatment plan therefore precedes the corresponding orthodontic treatment.

Orthodontic treatment using orthodontic aligners is the implementation of a treatment plan that defines models for the dental arch in anticipated shapes, before orthodontic treatment, for different times during orthodontic treatment. Generating a treatment plan typically includes the design of one or more orthodontic aligners and their modeling. An example of aligner design is described in “ History of Orthodontics ,” by Basavaraj Subhashchandra Phulari. The treatment plan thus defines models for the orthodontic aligners implemented, these models being used to manufacture the corresponding orthodontic aligners. The modeling of orthodontic splints can be carried out automatically, by computer, or manually, traditionally by a dental practitioner.

More precisely, a series of models of the user's arch are conventionally determined, which represent consecutive arch configurations, and a series of corresponding orthodontic splint models, making it possible to manufacture orthodontic splints adapted to each modify the configuration. of the arcade from a configuration represented by one arcade model to the configuration represented by the next arcade model.

Each treatment plan therefore “corresponds” to an orthodontic treatment, models of the arch at the start and end of the associated orthodontic treatment, and, if orthodontic treatment is implemented, one or more orthodontic aligners designed to achieve a configuration of the dental arch conforming to the model of the dental arch at the end of orthodontic treatment.

An example of software for manipulating tooth models and creating a treatment plan is the Treat program, described at https://en.wikipedia.org/wiki/Clear_aligners#cite_note-invisalignsystem-10. US5975893A also describes creating a treatment plan.

An “ orthodontic appliance ” is a device adapted to the implementation of orthodontic treatment. An orthodontic appliance can be intended for therapeutic or prophylactic treatment, but also for aesthetic treatment.

An orthodontic appliance may in particular be an arch and bracket appliance, or an orthodontic splint, or an auxiliary appliance of the Carrière Motion type. The configuration of an orthodontic appliance can be determined in particular to ensure its fixation on the teeth, but also according to a desired positioning for the teeth. More precisely, the shape is determined so that, in the service position, the orthodontic appliance exerts constraints tending to move the treated teeth towards their desired positioning.

A 3D scanner, or “ scanner ”, is a device used to obtain a model of a dental arch.

The “ service position ” is the position of an orthodontic appliance, for example an orthodontic splint, when it has been fixed on the arch in order to treat this arch. Conventionally, the attachment of an orthodontic splint can be deactivated by the user, by simply pulling on the splint.

By “ computer ”, we mean a computer processing unit, which includes a set of several machines, having computer processing capabilities. This unit can in particular be integrated into a scanner, or into a mobile phone, or be a PC type computer or a server, for example a server remote from the user, for example be the "cloud" or a computer located at home. a dental practitioner.

Conventionally, a computer comprises in particular a processor, a memory, a man-machine interface classically comprising a screen, a communication module via the Internet, by WIFI, by Bluetooth® or by the telephone network. A computer program configured to implement, at least partially, a method of the invention is loaded into the computer's memory. The computer can also be connected to a printer.

In a method according to the invention, different computers communicating with each other can be implemented for different stages, or, preferably, the same computer is implemented for all stages. The computer is preferably integrated into a mobile phone.

By “computer form” we mean a set of pages, that is to say made up of one or more pages, which are displayed on a computer screen and which allow the user to enter information.

A form is "dynamic" when it adapts based on information relating to the user previously acquired, on the displayed page or on previously displayed pages, for example by means of the dynamic form. It is therefore not predefined like a static questionnaire which asks for the same information, in the same way, regardless of the information previously entered, particularly by the user.

An area of a page of a form used so that the user can enter information into the computer is called an “input field” . An input field can be for example:
- a multiple choice question, for example with check boxes;
- an input area for text or a number;
- a cursor to move;
- a button to click on;
- an ordered set of buttons and/or check boxes and/or elements to select, for example of the “dental map” type, or “teeth map”, as shown in the .

The adjectives “first” and “second” are used to distinguish the input fields of the first and second form pages. The first and second input fields may be different or identical, for example if the first information only leads to modifying the appearance of the first input field.

By “ model ” we mean a digital three-dimensional model. A model is made up of a set of voxels, or “points”. A model can for example be of the type .stl or .Obj, .DXF 3D, IGES, STEP, VDA, or Point clouds. Advantageously, such a model, called “3D”, can be observed from any angle.

An “ arch model ” is a three-dimensional digital model that represents an arrangement of a user's teeth. Preferably, the model of an arch also represents other organs of the mouth, and in particular the gums.

The number of points of an arcade model is not limited. In one embodiment, an arch model, and in particular a final model, includes only the points strictly necessary for defining the arrangement of the teeth.

A “ tooth model ” is a three-dimensional digital model of a tooth in a user's arch. A model of an arch can be cut so as to define tooth models for at least a portion of the teeth, preferably for all of the teeth represented in the model of the arch. The tooth models are therefore models within the arch model. There shows an example view of an arch model divided into tooth models 32, only the tooth models being represented. There are computer tools for manipulating the tooth models of an arch model. These tools make it possible to impose constraints, in particular to limit the movements of the tooth models to realistic movements, for example to prevent adjacent tooth models from interpenetrating.

The number of points of a tooth model is not limited. In one embodiment, a tooth model includes only the points strictly necessary to define its configuration. In one embodiment, it has points likely to collide with other tooth models.

A point of a tooth model of the initial model is "matched" with a point of a tooth model of the final model (or a transition model) if the deformation scenario modifies the position of the point of the model of tooth of the initial model so that it merges substantially with that of the point of the tooth model of the final model at the final time (or from the transition model to the transition time).

According to the international convention of the International Dental Federation, each tooth in a dental arch, and therefore each tooth model, has a predetermined “ tooth number” . The tooth numbers defined by this convention are recalled on the .

A “ remarkable point ” is a point on an arch or tooth model that can be identified, for example the top of the tooth or at the tip of a cusp, an interdental contact point, it is that is, of a tooth with an adjacent tooth, for example a point mesial or distal to the incisal edge of a tooth, or a point at the center of the crown of the tooth, or "barycenter".

The “ cutting ” of an arch model into “tooth models” is an operation making it possible to delimit and make autonomous the representations of the teeth (tooth models) in the arch model. There are computer tools for manipulating the tooth models of an arch model. An example of software for manipulating tooth models is the Treat program, described at https://en.wikipedia.org/wiki/Clear_aligners#cite_note-invisalignsystem-10.

When an arch model is cut into tooth models, it is also possible to cut other models, for example a gum model.

The function of a “ reference frame ” is to serve as a basis for locating points in space, in particular for measuring a distance or for measuring an orientation or position, for example of a tooth model. A reference frame can for example be a three-dimensional reference frame, for example orthonormal. To determine an arrangement of the teeth of an arch model or a configuration of a tooth of the arch, a fixed reference frame with respect to the arch model is used. The reference frame can for example have its origin in the center of the user's oral cavity.

The “ configuration ” of a tooth or tooth model refers to its position and orientation in the frame of reference.

A “ deformation scenario ” is a set of chronologically ordered transition patterns. It is therefore the succession of transition models. It can be seen as a kind of 3D movie showing how the arcade model deforms in the space between the initial model and the final model.

The “ fragmentation ” of a deformation scenario consists of defining the intermediate moments, that is to say, specifying the moments at which, when the deformation scenario takes place, a check of the dental arch by a dental practitioner and /or a modification of an orthodontic appliance, in particular a change of orthodontic splint for orthodontic treatment with orthodontic splints, and/or the manufacture of an orthodontic appliance must be carried out.

An “orthodontic treatment plan” includes a deformation scenario and the intermediate times defined for this deformation scenario.

A “ stage ” is a period of the orthodontic treatment plan defined between the initial instant and the first intermediate instant, between two consecutive intermediate instants or between the last intermediate instant and the final instant.

A phase can typically include between 2 and 150 steps. For example, to correct a drift after orthodontic treatment to correct a malocclusion, or “relapse”, 2 or 3 orthodontic aligners may be sufficient. A complex malocclusion correction phase can require several dozen orthodontic aligners.

The “ pathway ” of a tooth model following a deformation scenario is the set of successive representations of the tooth model in the transition models of the deformation scenario. It can be considered as a kind of 3D movie showing how the tooth model moves in space, in translation and/or rotation, between the initial instant and the final instant. The determination of a deformation scenario by displacement of the tooth models thus involves the search for a set of paths for the models of the teeth of the arch.

The “ kinetic capabilities ” of a tooth model define the highest physiologically acceptable values for the movement speeds of that tooth model.

A greater physiologically acceptable value for a speed of a tooth model is therefore a speed beyond which a risk appears for the health of the user, for example a risk of tooth loosening. It depends on the nature of the tooth, or the tooth number. For example, an incisor accepts movement speeds greater than a molar.

A higher physiologically acceptable value for a tooth model speed can be defined based on the number of the tooth modeled, in particular on the basis of statistical data. It can also depend on the user, for example to take into account the presence of stops.

A greater physiologically acceptable value for a speed also depends on the type of movement considered, rotation or translation, and the direction of the movement considered, for example regression or intrusion. Preferably, the largest physiologically acceptable values are therefore defined for several movement speeds.

The “ movement speeds ” of a tooth model include a translation speed, for example the modulus of the speed vector, and a rotation speed.

To account for the different behavior of a tooth depending on the type of movement, movement speeds may include:
- the translation speeds along the different axes of a fixed reference frame relative to the arch model, of a point linked to the tooth model, preferably the barycenter of the tooth model, and
- the rotational speeds of the tooth model around each of said axes.

To take into account the different behavior of a tooth depending on the direction of movement, the movement speeds can also include said speeds in translation and in rotation by distinguishing each time the direction of the speed, for example to distinguish egression and the intrusion.

A movement speed of a tooth model corresponds to an anticipated movement speed for the modeled tooth, following an orthodontic treatment plan.

We “smooth” a deformation scenario when we reduce, preferably minimize, a speed parameter, preferably chosen from:
- the greatest value of a movement speed of said slowed tooth model reached between the initial instant and the final instant, and/or
- a speed representative of the speed of movement of said slowed tooth model, preferably an average speed between the initial instant and the final instant, and/or
- the difference between said largest value of said movement speed and the smallest value of said movement speed of said slowed tooth model between the initial instant and the final instant, and/or
- the variation of said speed of movement of said slowed tooth model, on average between the initial instant and the final instant.

A “ representative speed ” of a tooth model is a speed determined from one or more movement speeds of said tooth model, for example the module of the vector of the speed in translation of the barycenter of the tooth model, or of the vector of the rotational speed of a remarkable point on the surface of the tooth model.

A “ representative distance ” of the movement of a tooth model is a distance calculated from the movement of one or more points of the tooth model and/or one or more points linked to the tooth model, such as its barycenter. The length of the path traveled by the centroid of a tooth model following a deformation scenario is an example of a representative distance. Another example of a representative distance is the Euclidean distance between the centroid position of a tooth model in the final model and in the initial model.

A “ correct occlusion ” is an arrangement of the teeth of the two dental arches which allows contact of these two arches acceptable according to the rules of orthodontics. In particular, with correct occlusion, the cusps of the upper arch teeth do not contact the cusps of the lower arch teeth when the mouth is closed. The teeth in the two arches “fit together,” with the cusps of the teeth in one arch penetrating the grooves or interdental spaces of the teeth in the other arch.

By “ image ” we mean a two-dimensional image, such as a photograph or an image taken from a film. An image is made up of pixels.

By “ image of an arcade ”, “view of an arcade”, “representation of an arcade”, “scan of an arcade”, or “model of an arcade”, we mean an image, a view, a representation, scan or model of all or part of said dental arch, preferably representing at least 2, preferably at least 3, preferably at least 4 teeth. There shows an example view of an arcade model with 5000 points.

“ Metaheuristic” methods are known optimization methods. They are preferably chosen from the group formed by
- evolutionary algorithms, preferably chosen from evolution strategies, genetic algorithms, differential evolution algorithms, distribution estimation algorithms, artificial immune systems, Shuffled Complex Evolution path recomposition, simulated annealing, ant colony algorithms, particle swarm optimization algorithms, taboo search, and the GRASP method;
- the kangaroo algorithm, the Fletcher and Powell method, the noise method, stochastic tunneling, random hill climbing, the cross-entropy method, and
- hybrid methods between the metaheuristic methods cited above.

A “ statistical processing ” is a processing which, applied to a set of so-called “historical” data, makes it possible to determine characteristics specific to this set, for example an average, a standard deviation, or a median value. Statistical processing tools are well known to those skilled in the art.

“ Deep learning devices ” , called “deep learning” algorithms, are also well known to those skilled in the art. They include “neural networks” or “artificial neural networks”.

Those skilled in the art know how to choose and train a neural network according to the task to be performed. In particular, a neural network can be chosen from:
- networks specialized in image classification, called “CNN” (“Convolutional neural network”), for example AlexNet (2012), ZF Net (2013), VGG Net (2014), GoogleNet (2015), Microsoft ResNet ( 2015) Network (Imagenet & CIFAR-10), Google: Inception (V3, V4),
- networks specialized in the localization and detection of objects in an image, called “Object Detection Networks”, for example R-CNN (2013), SSD (Single Shot MultiBox Detector: Object Detection network), Faster R-CNN ( Faster Region-based Convolutional Network method: Object Detection network), Faster R-CNN (2015), SSD (2015), RCF (Richer Convolutional Features for Edge Detection) (2017), SPP-Net, 2014, OverFeat (Sermanet et al .), 2013, GoogleNet (Szegedy et al.), 2015, VGGNet (Simonyan and Zisserman), 2014, R-CNN (Girshick et al.), 2014, Fast R-CNN (Girshick et al.), 2015, ResNet (He et al.), 2016, Faster R-CNN (Ren et al.), 2016, FPN (Lin et al.), 2016, YOLO (Redmon et al.), 2016, SSD (Liu et al.), 2016, ResNet v2 (He et al.), 2016, R-FCN (Dai et al.), 2016, ResNeXt (Lin et al.), 2017, DenseNet (Huang et al.), 2017, DPN (Chen et al.) .), 2017, YOLO9000 (Redmon and Farhadi), 2017, Hourglass (Newell et al.), 2016, MobileNet (Howard et al.), 2017, DCN (Dai et al.), 2017, RetinaNet (Lin et al. ), 2017, Mask R-CNN (He et al.), 2017, RefineDet (Zhang et al.), 2018, Cascade RCNN (Cai et al.), 2018, NASNet (Zoph et al.), 2019, CornerNet ( Law and Deng), 2018, FSAF (Zhu et al.), 2019, SENet (Hu et al.), 2018, ExtremeNet (Zhou et al.), 2019, NAS-FPN (Ghiasi et al.), 2019, Detnas (Chen et al.), 2019, FCOS (Tian et al.), 2019, CenterNet (Duan et al.), 2019, EfficientNet (Tan and Le), 2019, AlexNet (Krizhevsky et al.), 2012
- networks specialized in image generation, for example Cycle-Consistent Adversarial Networks (2017), Augmented CycleGAN (2018), Deep Photo Style Transfer (2017), FastPhotoStyle (2018), pix2pix (2017), Style-Based Generator Architecture for GANs (2018), SRGAN (2018).

The list above is not exhaustive.

Training a neural network consists of confronting it with a learning base containing information on the two types of object that the neural network must learn to “correspond”, that is to say to connect one to the other.

Training can be done from a learning base made up of recordings each comprising a first object of the first type and a second corresponding object, of the second type.

Alternatively, training can be done from a learning base made up of recordings each comprising either a first object of the first type, or a second object of the second type, each recording however comprising information relating to the type of object it contains. Such training techniques are for example described in the article by Zhu, Jun-Yan, et al. “ Unpaired image-to-image translation using cycle-consistent adversarial networks. ”

Training the neural network with these recordings teaches it to provide, from any object of the first type, a corresponding object of the second type.

The quality of the analysis carried out by the neural network depends directly on the number of recordings in the learning base. Preferably, the learning base includes more than 10,000 records and/or less than 10,000,000 records.

“Understand”, “include” or “present” must be interpreted broadly, without limitation, unless otherwise indicated.

Other characteristics and advantages of the invention will appear further on reading the detailed description which follows and on examining the appended drawing in which:
- there schematically illustrates a method according to the first main aspect of the invention;
- there represents an example of a model acquired with a portable scanner integrated into a mobile phone and comprising 5000 points;
- [ ] there represents an example of an arch model divided into tooth models, referenced 32 (only the tooth models are represented);
- there illustrates the numbering of teeth used in the dental field;
- [ ] there schematically illustrates a method according to the second main aspect of the invention;
- [ ] there schematically illustrates a form page for a method according to the third main aspect of the invention;
- [ ] there schematically illustrates a method according to the third main aspect of the invention;
- there represents an example of a dental card usable in a dynamic form according to the invention.

Other details and advantages of the invention are provided in the detailed description which follows, provided for illustrative and non-limiting purposes.

detailed description

The method according to the first and second aspects of the invention aims to generate a plan for orthodontic treatment which extends between an initial moment and a final moment. It can plan a complete or partial orthodontic treatment, that is to say insufficient to achieve, on its own, the desired configuration for the user.

A partial orthodontic treatment corresponds to a phase of a complete orthodontic treatment, for example a distalization phase intended to separate the teeth in order to then be able to reposition them, or a phase of alignment of the barycenters of the teeth following the curve of the arch who wear them, or a phase of rotation of the teeth around their barycenters.

In one embodiment, the method is implemented several times, for each of the phases of a complex orthodontic treatment.

In step A'), the computer determines the initial model for the first phase, or "first phase start model". This model represents the dental arch before the start of complex orthodontic treatment. The computer cuts it into tooth models, as in step a).

The computer, preferably a computer-assisted dental practitioner, also determines the final model for the last phase, or "last end-of-phase model", as in step a). This model represents the dental arch as desired at the end of complex orthodontic treatment.

In step B'), the computer or a computer-assisted dental practitioner determines, by moving the tooth models, the end-of-phase models for each phase until the penultimate phase, the model end of phase of the last phase having been determined in step A').

The end of phase model of a phase represents an objective to be achieved at the end of said phase. The start-of-phase pattern of a phase is the end-of-phase pattern of the phase that precedes it in time.

In a preferred embodiment, the computer defines the end-of-phase models, except possibly the last one, from the first start-of-phase model and the last end-of-phase model. To this end, we first teach the rules of orthodontics necessary to define the phases.

For example, in the previous example, after determining which tooth models need to be moved, by comparing the first phase start model and the last phase end model, the computer can move the tooth models. tooth of the first model at the start of the phase until they are sufficiently spaced apart so that their centroids can then be aligned following the curve of the arch, then rotated on themselves so that the extrados of the tooth models are substantially aligned. The model obtained can be considered as the first end-of-phase model.

Based on this model, the computer can then move the tooth models to align them with the curve of the arch. The resulting model can be considered as the second end-of-phase model.

Starting from this model, the computer can then rotate the tooth models to align their extrados faces. The resulting model can be considered as the third end-of-phase model.

To find end-of-phase patterns, the computer can use optimization algorithms, particularly simulated annealing.

In step C'), the computer implements, for each phase, a method according to the first and/or second aspect(s) of the invention. For each occurrence of this process, the initial model used is the start model of said phase and the final model used is the end model of said phase.

We now describe in detail an example of a method according to the first embodiment. In this example, we consider that the orthodontic treatment to be planned has only one phase.

In step a), we generate the initial and final models.

Initial model

The initial model is a digital three-dimensional model representing the teeth to be moved, in their arrangement on the dental arch planned at the start of orthodontic treatment, that is to say at the initial moment.

The initial model is preferably prepared from measurements made on the user's teeth or on a physical model of their teeth, for example a plaster model.

The initial model is then preferably produced less than a month before the initial moment, preferably less than 2 weeks, preferably less than a week before the initial moment, so that it corresponds well to the arrangement of the teeth at the start of orthodontic treatment.

The initial model is preferably created by means of a professional device, for example by means of a 3D scanner, preferably implemented by a dental practitioner, for example by an orthodontist or an orthodontic laboratory. In an orthodontic practice, the user or the physical model of their teeth can be advantageously arranged in a precise position and the professional device can be perfected. This results in a very precise initial model. The initial model preferably provides information on the positioning of the teeth with an error less than 5/10 mm, preferably less than 3/10 mm, preferably less than 1/10 mm.

In one embodiment, the arrangement of the teeth could have evolved between the time of initial model generation and the initial time. The initial model may, for example, have been generated more than a month or more than two months before the initial moment. The initial model is then updated, preferably deformed, preferably by a movement of one or more tooth models, to match the arrangement of the teeth at the initial time. In particular, the initial model can be distorted to correspond to one or more photos of the dental arch taken less than a week before the initial moment.

The number of points of the initial model is preferably greater than 5,000, 10,000 or 15,000 and/or less than 100,000. It then accurately represents the teeth. However, the computer manipulation of an initial model can be slowed down if the number of points is high.

In one embodiment, the initial model has less than 5,000 points, or even less than 1000 points, which makes it possible to accelerate the implementation of the process. In particular, the time required to generate a deformation scenario, in particular following the first optimization algorithm described below, depends on the number of points of the initial model used to determine the first distance.

An initial model comprising less than 5000 points, or “coarse model”, may in particular result from a simplification of a fine initial model, preferably acquired with a 3D scanner, for example comprising more than 10,000 or 20,000 points. The number of points of the initial model is preferably greater than 1,000 and/or less than 500,000.

In one embodiment, the simplification of an initial model results from a random selection of points on the surface of the initial model. In one embodiment, the initial model includes all the points which correspond to a point in the final model. Preferably, the initial model only includes points which correspond to a respective point of the final model. In one embodiment, the initial model does not include points whose position cannot be affected by the orthodontic treatment. In one embodiment, the initial model only includes a set of points strictly sufficient to define the position and orientation in space of each tooth model. For example, for each tooth model, it only has three remarkable non-aligned points. Preferably, said set of points also includes points likely to collide with adjacent tooth models, for example points of a tooth model which, in the initial model, are close to an adjacent tooth model .

A match can be established between the tooth models in the fine model and in the coarse model, which allows, if a deformation scenario has been generated with a coarse initial model and thus includes coarse transition models, to reconstruct models fine, high-precision transitions, for example usable to manufacture an orthodontic splint.

To deform an initial model, it is cut to generate a digital three-dimensional model for each tooth, or “tooth model”. Then the tooth models are moved.

Preferably, the initial model is also cut to generate a digital three-dimensional model for the gum, or "initial gum model".

Final model

The final model is a digital three-dimensional model representing the user's teeth in their arrangement on the dental arch as desired at the end of orthodontic treatment, that is to say at the final, future moment. It is therefore a theoretical model.

The objective of the final model is to provide the information necessary to define the orientation and position of each tooth in the arch at the final moment. The final model may be less accurate than the initial model. The position of a tooth model can in fact be defined by the position of a remarkable point of this tooth model, for example by the position of its barycenter. The orientation of a tooth model can be defined by two non-parallel vectors, whose common origin is for example the barycenter of the tooth model. Three remarkable points, for example the barycenter and two points not aligned with the barycenter of a tooth model can therefore be sufficient to define the configuration of a tooth. The final model can thus be made up of a set comprising, for each tooth model, coordinates of three remarkable points of this tooth model.

Determining the positioning of a tooth is for example described in the article “Dense Representative Tooth Landmark/axis Detection Network on 3D”, by Guangshun Wei, Zhiming Cui, Jie Zhu, Lei Yang, Yuanfeng Zhou, Pradeep Singh, Min Gu , Wenping Wang, https://arxiv.org/pdf/2111.04212v2.pdf.

The final model may result from a deformation of the initial model by displacement of tooth models.

It can be conventionally determined by a dental practitioner, by moving tooth models, for example with the Treat program, described on the page https://en.wikipedia.org/wiki/Clear_aligners#cite_note-invisalignsystem-10.

In a preferred embodiment, in step a), the computer analyzes the initial model and deduces a final model. No manipulation of the tooth model is then necessary to define the final model. In one embodiment, however, the dental practitioner imposes constraints, for example depending on the orthodontic treatment envisaged.

In one embodiment, a computer memory contains a “historical” database comprising a set of records, each record associating an initial historical model and a final historical model. The historical initial and final models may in particular be models representing tooth arrangements of historical users at the beginning and end of “historical” orthodontic treatments.

The analysis of the initial model by the computer can then consist of
- search, in the database, for the closest historical initial model, that is to say which presents the form closest to that of the initial model for which we are looking for a final model, then
- choose, for said final model, the final historical model associated with the closest initial historical model.

The user's dental arch is thus assimilated to the closest historical initial model and it is considered that the associated final historical model can also be used for the user.

A historical database can also be used to train one or more neural networks to provide the position and/or orientation of the tooth models in the final model. For example, we can provide
- as input, records each containing a tooth number and data defining a configuration of a tooth bearing said number for a historical user, and
- at output, records each containing a tooth number and data defining an ideal configuration of a tooth bearing said number.

In particular, we can use a network specialized in image classification among those mentioned above.

In one embodiment, the computer uses predefined rules to transform the initial model into a final model. The predefined rules can for example specify that, in the final model, the teeth must be aligned, specify a gap between the vertices of adjacent tooth models, or specify an orientation for each tooth.

In one embodiment, the initial model is analyzed to
- determine a curved base line following the curvature of the arch, for example connecting the barycenters of the teeth, as well as the length of the arch, for example the length of the base line;
- determine, on said baseline, the theoretical position and orientation of each tooth, according to predefined rules.

The algorithms making it possible to determine a baseline and the configuration of the teeth are well known, in particular for the production of panoramic images by tomography. In particular, we can use a mean square value, with a typical function of ax ⁴ +bx ² +c = 0.

The predefined rules can for example specify, depending on the length and curvature of the arch, how the different teeth should be distributed and oriented along said baseline.

The predefined rules can for example be obtained by statistical processing of historical data providing, as a function of the length and curvature, said distribution and said orientation of “historical” teeth of historical arches of historical users.

The computer can advantageously determine the final model very quickly, without human intervention.

Algorithms for comparing the shapes of two models are well known. For example, we know the ICP or “Iterative closest point” algorithm, described in particular in the online encyclopedia Wikipedia .

In a preferred embodiment, the initial model of the arch is cut to generate an initial gum model, and it is checked whether the arrangement of the tooth models in the final model is compatible with the initial gum model. This verification can be carried out by a dental practitioner and/or by a computer, independently or controlled by an operator, for example a dental practitioner. Preferably, it is checked whether the tooth models in the final model penetrate the initial gum model and/or whether a physiologically unrealistic gap has arisen between the tooth models in the final model and the initial gum model. In the case of such a penetration or space, the initial gum model is transformed into a final gum model so as to eliminate said penetration or space.

In step b ), the computer determines a series of successive deformations of the initial model leading to a final model.

The models resulting from successive elementary deformations before reaching the final model are called “transition models”. Each transition model therefore represents the arrangement of the teeth at a respective transition moment.

The number of transition models is preferably greater than 3, preferably greater than 10 and/or less than 1000. It is preferably determined so that no point of the arch model moves more than 1000 µm , 500 µm or 100 µm between two consecutive transition models and/or so that at least one point of the arch model moves more than 10 µm, 50 µm or 100 µm between two consecutive transition models. The precision of the deformation scenario is improved.

Each elementary deformation must respect a set of constraints. The constraints include:
- anatomical constraints, for example to impose that, during elementary deformation, a tooth model cannot penetrate an adjacent tooth model, and/or that the positions of one or more points of a tooth model must be contained in a defined envelope around the tooth model, and/or that the translation speed of a tooth model in one direction and in one direction must remain less than a defined upper limit for a translation speed, and/ or that the rotational speed of a tooth model around an axis and in one direction must remain less than a defined upper limit for a rotational speed;
- preferably, clinical constraints imposed by the rules of orthodontics and/or the dental practitioner, for example imposing, during elementary deformation, immobility of one or more tooth models, for example due to a gum problem, bone density or the presence of one or more dental implants, and/or imposing technical constraints to be respected in order to move a tooth model, for example due to the orthodontic appliances available, and/or favoring movements in relation to others, and/or imposing an order for moving the tooth models, and/or imposing a correct occlusion, and/or authorizing or prohibiting filing (in English “stripping”) of the teeth, and/or authorizing a limited filing of the teeth, and/or authorizing or prohibiting an extraction of one or more teeth, and/or imposing a movement of one or more teeth as homogeneous as possible, that is to say limiting as much as possible the variations in movement speeds of one or more teeth, and/or imposing an upper limit for a movement speed of one or more teeth, and/or imposing the presence of one or more phases and/or an order of execution of said phases;
- preferably, prescription constraints imposed by the user due for example to a need for orthodontic treatment generating limited pain and/or having a limited duration and/or having a limited cost, and/or having a number of limited steps and/or having a predetermined number of steps, and/or authorizing or prohibiting filing of teeth, and/or authorizing limited filing of teeth, and/or authorizing or prohibiting extraction of one or more teeth , and/or authorizing or prohibiting the use of one or more auxiliary orthodontic appliances.

The set of constraints imposed on an elementary deformation can be different depending on the arch model on which the elementary deformation is applied, or “model to be deformed”, namely the initial model or a transition model. For example, the possible positions and orientations for a tooth model can be limited by the presence of adjacent tooth models, whose positions and orientations can themselves be modified with each elementary deformation.

In one embodiment, the set of constraints includes constraints which can lead to an elementary deformation not directly applicable in reality. In particular, the constraint set may allow limited penetration of one tooth model into an adjacent tooth model. The resulting elementary deformation then requires, to be operational, a filing of one or both teeth whose tooth models penetrate one into the other. Preferably, the computer informs the dental practitioner of the need to perform such filing.

All or part of the constraints can be determined from information entered by the user, preferably by means of a dynamic form. There illustrates an example page of such a form. There illustrates the use of a dynamic form according to the third main aspect of the invention.

The user can in particular specify
- a maximum number of orthodontic aligners for orthodontic treatment, that is to say a maximum number of intermediate moments;
- the numbers of the teeth which must remain immobile during orthodontic treatment, in particular by clicking on the boxes bearing the numbers of these teeth.

There represents for example a dental card. The user can select one or more teeth by clicking on the representation of the number of said teeth on this map.

The page shown on the further allows the user to specify treatment objectives, which can be used by the computer to determine a model of the arch at the end of orthodontic treatment.

The determination of the elementary deformations, and therefore of the deformation scenario, is preferably carried out by means of a computer program called “generator”, implemented by the computer.

Preferably, the initial model is cut by the computer. Cutting the initial model to determine the models of the organs it represents is a well-known operation. Preferably, the initial model is cut to define at least the parts which represent the teeth, or “tooth models”. The tooth models can be defined as described, for example, in international application PCT/EP2015/074896.

To determine an elementary deformation, the generator moves tooth models, while respecting all the constraints. The elementary deformations include, and are preferably exclusively, movements of tooth models.

The determination of an elementary deformation is fast, even if the tooth models are moved randomly, in particular if the number of points of the initial model is small. However, determining a deformation scenario can be very long.

To speed up the search for a deformation scenario, the generator can implement rules used by dental practitioners to generate an orthodontic treatment plan. For example, he can
- promote movements of the tooth models according to the shortest or fastest path towards the final model, taking into account one or more tooth models, for example by defining said path as the sum of the paths traveled by several models of tooth, preferably taking into account all tooth models, and
- only deviate from this path in the event of a collision with an adjacent tooth model.

Preferably, the generator implements a first optimization algorithm, preferably a metaheuristic method, preferably evolutionary, preferably by simulated annealing. The first optimization algorithm can in particular be chosen from the algorithms listed above in the definition of metaheuristic methods.

The first optimization algorithm can implement the following steps:
i) creation of a scenario “to be tested”, that is to say application, to the initial model, of a set of successive elementary deformations “to be tested”, preferably exclusively by moving tooth models, so as to to obtain an arcade model “to test”;
ii) determination of a first distance measuring a difference in shape between the model to be tested and the final model:
iii) comparison of said first distance to a first threshold so as to obtain a first score for the scenario to be tested;
iv) if the first score is insufficient, for example greater than a first predetermined minimum score, modification of the scenario to be tested and return to step i).

The cycle of steps i) to iv) is thus repeated until the score of the scenario to be tested is satisfactory, that is to say the model to be tested can be considered sufficiently close to the final model. The scenario to be tested can then be considered as a “deformation scenario”.

In step i), the scenario to be tested can be generated randomly.

It is preferably created taking into account the scores obtained in previous cycles, for example to avoid applying elementary deformations which do not produce good scores. Preferably, the creation of a test scenario is guided by rules used by dental practitioners to generate an orthodontic treatment plan. For example, the scenario to be tested can be chosen to favor movements of the tooth models according to the shortest path towards the final model and only deviate from this path in the event of collision with an adjacent tooth model.

In step i), the scenario to be tested can in particular be the scenario to be tested from the previous cycle to which an additional elementary deformation is added. In other words, the model to be tested results from an additional elementary deformation applied to the model to be tested from the previous cycle. The scenario to be tested thus “extends” from one cycle to the next until an acceptable scenario is reached. In one embodiment, such construction of the deformation scenario is stopped if said first distance becomes greater, with a predetermined difference, possibly zero, than that of a scenario to be tested previously determined.

In step ii), said first distance is for example the sum of the Euclidean distances between points of the model to be tested and the corresponding points of the final model.

In step iii), the first score can for example be the inverse of the difference between said first distance and the first threshold. The first threshold can be zero, so that the cycle of steps i) to iv) leads to the final model.

Preferably, the generator generates several arch deformation scenarios then chooses the one which minimizes a distance with an ideal deformation scenario, for example inducing a minimum total deformation. Such a deformation scenario is called an “optimal deformation scenario”.

More preferably, the generator implements a second optimization algorithm in order to search for an optimal deformation scenario. The second optimization algorithm is preferably a metaheuristic method, preferably evolutionary, preferably by simulated annealing. The second optimization algorithm can in particular be chosen from the algorithms listed above in the definition of metaheuristic methods.

The second optimization algorithm can implement the following steps:
i') creation of a deformation scenario “to be tested”, preferably by means of the first optimization algorithm;
ii') measurement of a second distance measuring a difference between the deformation scenario to be tested and an ideal arch deformation scenario;
iii') comparison of said second distance to a second threshold so as to obtain a second score for the deformation scenario to be tested, the second score being able for example to be the inverse of the difference between said second distance and the second threshold;
iv') if the second score is insufficient, for example greater than a second predetermined minimum score, modification of the deformation scenario to be tested and return to step i').

The cycle of steps i') to iv') is thus repeated until the score of the deformation scenario to be tested is satisfactory, that is to say the deformation scenario to be tested can be considered sufficiently close of the ideal deformation scenario. The deformation scenario to be tested is then an “optimal” deformation scenario.

The second distance can for example be the cumulative Euclidean distance traveled by a set of points of the initial model, for example all the points of the initial model, during the deformation scenario to be tested. This Euclidean distance is preferably minimal in an ideal deformation scenario, so that the second threshold can for example be zero and the second score equal to the second distance. The set of points preferably comprises one, preferably more than 1, more than 2 points for at least one tooth model of the initial model, preferably at least two, preferably at least 3 tooth models of the initial model, preference for each tooth model of the initial model. The second distance can give weights greater than the Euclidean distances traveled by certain points, for example by points belonging to tooth models representing teeth whose movement must be particularly limited.

If the second threshold is zero, the second distance can define the second score. Step iii’) is then unnecessary. It is therefore optional.

Preferably, the second distance takes into consideration one or more prescriptions dictated by the user. For example, the user may have completed a computer questionnaire in the computer to specify these prescriptions, for example to specify the relative importance he gives to the speed of the orthodontic treatment, and/or to the pain generated by the treatment. orthodontic treatment, for example measured by a pain coefficient, and/or comfort during orthodontic treatment, for example measured by a comfort coefficient, and/or the cost of orthodontic treatment.

Comfort can in particular refer to the aesthetic impact of orthodontic treatment.

In one embodiment, the second distance therefore depends on the duration and/or a pain coefficient and/or a comfort coefficient and/or a cost associated with the deformation scenario to be tested. The duration, the pain coefficient and the cost are preferably minimal in an ideal deformation scenario, so that the basis for comparison of these criteria can be for example equal to 0. The comfort coefficient is maximum in the deformation scenario ideal, so that the basis for comparison of this criterion can be for example the maximum possible value for this coefficient.

The allocation of a duration (or a duration coefficient normalizing the duration) and/or a pain coefficient and/or a comfort coefficient and/or a cost (or a coefficient cost normalizing the cost) to a deformation scenario to be tested can be determined, by a dental practitioner or, preferably, by an evaluation module programmed in the computer implementing rules conventionally applied by dental practitioners or determined by the computer using statistical processing. The deformation scenario to be tested can for example be compared to historical arch deformation scenarios from a database in order to determine a similar historical deformation scenario, and inherit information on duration, pain coefficient, the comfort coefficient and/or cost.

The criteria (duration, pain coefficients, comfort coefficient, cost) for historical arch deformity scenarios can be evaluated from surveys carried out among people who have been treated according to said historical arch deformity scenarios and/or from dental practitioners who performed these treatments.

A neural network can also be trained to assign a duration (or a duration coefficient) and/or a pain coefficient and/or a comfort coefficient and/or a cost (or a cost coefficient) to a deformation scenario. to test. We can in particular use a network specialized in image classification among those cited above, not trained to provide probabilities of occurrence of different predefined classes, but trained to provide a value in an infinite set of values, c 'that is to say a continuous value. For training, we can thus provide a deformation scenario, or preferably only the initial and final models, as input and a duration (or a duration coefficient), a pain coefficient, a comfort coefficient or a cost ( or a cost coefficient) associated with this deformation scenario.

For example, if
- L_idesignates the distance traveled by a point Pi of a tooth model of the arch following the deformation scenario to be tested,
-k₁designates a weight for a duration coefficient, for example between 1 and 10, preferably provided by the user, depending on the importance he attaches to the speed of orthodontic treatment,
-k₂designates a weight for a pain coefficient, for example between 1 and 10, preferably provided by the user, depending on the importance he gives to the pain that orthodontic treatment will eventually inflict on him,
-k₃designates a weight for a comfort coefficient, for example between 1 and 10, preferably provided by the user, depending on the importance he attaches to comfort during orthodontic treatment, and
-k₄designates a weight for a cost coefficient, for example between 1 and 10, preferably provided by the user, depending on the importance he gives to the cost which will be generated by the orthodontic treatment,
- C designates a prescription factor taking into account the duration coefficients C₁, and/or pain C₂and/or comfort C_{3 ,}and/or cost C₄, associated(s) with a deformation scenario to be tested, for example equal to a polynomial function of these coefficients, for example equal to (k₁*VS₁+k₂*VS₂+ k₃*VS₃+ k₄*VS₄),
the second distance and/or the second score could be for example:
- the sum ofL _i , for a set of N points “i”, N being preferably greater than 10 ; Or
- the product of the sum ofL _i , for a set of N points “i”, by the prescription coefficient.

In one embodiment, we first search for a deformation scenario, preferably an optimal deformation scenario, with a rough initial model, for example containing 100 points. Then we complete the initial, transition and final models in order to check the absence of unacceptable collision, i.e. one that cannot be removed by filing, in the case where filing is authorized. In the event of an unacceptable collision, that is to say if the computer notes that the deformation scenario includes an interpenetration of adjacent tooth models beyond an acceptable limit, points are added to the initial model, and we renews said search with the simplified initial model of the previous cycle to which the points have been added.

In a preferred embodiment, the initial model of the arch is cut so as to generate an initial gum model, and, successively for each transition model, it is checked whether the arrangement of the tooth models in the transition model is compatible :
- with the initial gum model, for the first transition model, or
- with the gum model in the previous transition model, for the following transition models.

This verification can be carried out by a dental practitioner and/or by a computer, independently or controlled by an operator, for example a dental practitioner. Preferably, it is checked whether the tooth models in the considered transition model penetrate the gum model and/or whether a physiologically unrealistic gap has arisen between the tooth models and the gum model. In the case of such a penetration or space, the gum model is modified so as to eliminate said penetration or space. Each transition model thus presents a representation of the gum compatible with the arrangement of the tooth models.

At the stage vs ), the computer determines the final instant for the scenario determined in step b).

For this purpose, the deformation scenario can for example be compared to historical arch deformation scenarios from a database providing, for each historical arch deformation scenario, the associated treatment duration.

The duration of the scenario, and therefore the final instant, can then be determined from the duration of a similar historical deformation scenario, for example chosen as equal to the duration of the similar historical deformation scenario.

The stages of orthodontic treatment in the deformation scenario resulting from stage b) are marked by the intermediate moments at which a check of the arch by a dental practitioner and/or a modification of an orthodontic appliance worn by the user and /or an orthodontic appliance intended for the user must be manufactured.

Modification of an orthodontic appliance worn by the user may consist of modifying the structure or shape of this appliance, or replacing it with a new orthodontic appliance. In one embodiment, the intermediate times are the times at which orthodontic aligner replacements are scheduled.

The intermediate moments are preferably moments when a change of orthodontic splint is planned.

The intermediate instants can be chosen so that the time interval between two consecutive intermediate instants, preferably between any two consecutive intermediate instants, is in a predetermined range, preferably is constant and/or is equal to the maximum duration of use of orthodontic appliance, for example the duration of use of an orthodontic splint.

The transition models at intermediate times are the “intermediate models”.

The number of intermediate models is preferably less than 0.1 times the number of transition models. It is preferably greater than or equal to 1 and/or less than 150.

In one embodiment, the number of intermediate models is equal to the number of transition models.

Preferably, the intermediate times and the final time are determined according to the movements of the tooth models following the deformation scenario and the orthodontic appliances envisaged. The possibilities of moving the teeth following the different possible movements in translation and rotation are in fact different depending on the number of the tooth considered and the orthodontic appliance considered. For example, due to the capabilities of the polymer used to manufacture orthodontic splints, a translation for the intrusion or egression of a tooth between two stages can be limited to less than 0.1 mm, a rotation can be limited to less than 3° degrees of rotation, tip or torque, etc. These constraints linked to the properties of orthodontic aligners make it possible, by knowing the necessary movements between the initial model and the final model, to calculate intermediate times and a final time compatible with orthodontic aligners and orthodontic treatment.

The way of determining the intermediate moments and the final moment is not restrictive. The rules classically used by dental practitioners to choose the most suitable intermediate moments can be applied by the computer.

In a preferred embodiment, the computer proceeds as follows:

The initial model is divided into tooth models and the elementary deformations of the deformation scenario result from displacement of the tooth models, in translation and/or rotation. Preferably, the number of each tooth represented in the initial model is identified when cutting the initial model, by labeling carried out by an operator or, preferably, by shape recognition carried out by the computer, for example by means of a neural network. Such shape recognition carried out by the computer is well known to those skilled in the art.

A tooth has kinetic displacement capacities which are different depending on the nature of this tooth. In particular, the greatest physiologically acceptable values of movement speeds, in translation or in rotation of a tooth, according to the different directions of space, depend on the number of the tooth. These displacement capacities make it possible to define constraints for each set of constraints imposed for each elementary deformation. In particular, these constraints can set, for each tooth model, upper limits for speeds of movement, in translation and in rotation, according to the different axes of a frame of reference, for example an orthonormal reference, fixed in relation to the skull of the user. The upper limit of a movement speed may in particular be the greatest physiologically acceptable value for this speed.

The kinetic movement capacities of the teeth can be determined by statistical analysis, in particular by analysis of panoramic x-rays and/or cephalometric x-rays of historical users. They can also be determined by analysis of panoramic x-rays and/or cephalometric x-rays of the user implementing the method. In one embodiment, kinetic tooth movement capacities are determined by statistical analysis of historical data, that is to say relating to historical users, then the values obtained are refined according to the user for whom we implements the process, for example to take into account its bone density per tooth and/or the condition of its gums.

From a computer table giving, for each tooth number, the upper limits of the speeds of movement, in translation and in rotation, according to the different axes of the frame of reference, the computer can therefore determine said upper limits for each tooth model .

Furthermore, for a deformation scenario, the “pathway” of a tooth model includes all the configurations of the tooth model from the initial model to the final model, that is to say in the initial models , transitional and final. It is thus possible to determine the distance traveled in space by each point of a tooth model during the deformation scenario. It is also possible to determine the angular sector traveled, around each of the three axes of the frame of reference, by each tooth model during the unfolding of the deformation scenario.

For each tooth model, considering that it moves at the highest possible movement speeds while respecting the constraints, that is to say as much as possible at the upper limits of these speeds defined by the constraints, it is thus possible to determine the smallest possible duration for this tooth model to modify its configuration from the initial model to the final model, following the deformation scenario.

The tooth model that imposes the longest duration is called the “limiting tooth model” because the deformation scenario cannot be performed any faster. This duration, which is the duration of the orthodontic treatment plan, can be added to the initial moment to determine the final moment and it is possible to date each moment of the deformation scenario.

The limiting tooth model can be defined by analysis of the paths of the different tooth models, following the deformation scenario, preferably by computer. Alternatively, the limiting tooth model can be predefined, for example because it is classically identified as limiting for orthodontic treatment.

The deformation scenario is then fragmented so that the limiting tooth model can follow its path, the intermediate moments defining the fragmentation being determined according to the capabilities of the orthodontic appliance(s) to implement the deformation scenario. For example, it is possible to define the times at which the orthodontic appliance worn by the user must be adapted so that the limiting tooth model can follow its path.

In particular, in the context of orthodontic treatment using orthodontic aligners, an orthodontic aligner only allows limited movement of a tooth. For example, its limited elasticity can impose a displacement of any point of any tooth always less than a limit of approximately 1 mm, or even always less than 0.5 mm. In other words, as soon as a point on a tooth has moved 1 mm since the orthodontic splint was installed, the orthodontic splint must be changed. Knowledge of the tooth movement capabilities possible with an orthodontic splint thus makes it possible to determine the intermediate moment at which the orthodontic splint must be changed.

For example, for an orthodontic treatment in which a molar must move 3 mm and a canine must move 4 mm, the upper limit for the speed of movement of the molar being 1 mm per month and that of the canine being 2 mm per month, it takes at least 3 months to move the molar and 2 months to move the canine. The molar model is therefore the limiting tooth model and the duration of orthodontic treatment is 4 months. The intermediate times can be chosen to mark each time a movement of 1 mm since the previous time (intermediate or initial) if the orthodontic aligners are adapted to ensure a movement of 1 mm each. The intermediate times are therefore, if t ₀ is the initial time, to be at t ₀ + 1 month, t ₀ + 2 months, and t ₀ + 3 months.

The orthodontic treatment plan thus defined may, however, impose a path for a model of a molar which is very rapid, leading to pain for the user and/or an increased risk for the health of the user. The following step d), and the second main aspect of the invention make it possible to respond to this problem.

In step d), optional, in a particularly advantageous embodiment, the generator, preferably the first and second optimization algorithms, is/are used to search for a new deformation scenario, preferably optimal, called "smoothed". ", but with, for each elementary deformation, a new set of constraints imposing
- for the limiting tooth model, compliance with the path determined according to the deformation scenario determined in step b), and
- for at least for a tooth model other than the limiting tooth model, called “slowed down tooth model”, a reduction, preferably an optimization of a said speed parameter.

Preferably, the new set of constraints imposes upper limits for movement speeds lower than those obtained following the orthodontic treatment plan resulting from step c). In other words, the set of constraints imposes that the speeds of said slowed tooth model, modeling a “slowed down tooth”, cannot reach the maximum values that the nature of said other tooth would authorize. For example, it imposes, for one or more of the slowed tooth movement speeds, an upper limit lower than the upper limit imposed to establish the orthodontic treatment plan resulting from step c).

Smoothing advantageously makes it possible to improve the predictability of the treatment, that is to say, to increase the conformity between the orthodontic treatment plan and its subsequent translation in the user's mouth.

Preferably, we limit the amplitude of the speed variation during the movement of the slowed tooth during the duration of the treatment, that is to say we reduce the difference between the highest speed and the lowest speed. lowest achieved during the duration of treatment. For this purpose, the computer can also impose one or more minimum values at one or more speeds of the slowed tooth model, that is to say low limits for said speeds.

More preferably, the computer calculates at least one average speed of the slowed tooth model according to the deformation scenario obtained at the end of step c), for example an average speed of a point in translation or rotation around of an axis, on average over the duration of the orthodontic treatment plan resulting from step c). The set of constraints then imposes that the instantaneous speed of said slowed tooth model cannot vary by more than a certain percentage of said average speed, for example by more than +/- 20% or +/- 10%. Advantageously, the movement of said slowed tooth model is thus more regular.

The deformation scenario thus smoothed advantageously limits the risks for the user.

Smoothing can be performed for several teeth simultaneously when the new set of constraints imposes that the speeds of several slowed-down tooth models cannot reach the maximum values that the nature of the teeth they model would allow.

In a preferred embodiment, smoothing is carried out successively for several slowed tooth models.

At each iteration of step d), the computer adds to the constraints compliance with a new path for a tooth model whose path was not imposed during previous steps d). Smoothing is preferably done tooth by tooth, preferably starting with the teeth where rapid movement is most likely to be detrimental to the user. In other words, preferably, the first smoothing operations concern the teeth whose rapid movement is the most detrimental for the user.

In the example above, the generator can thus search for a smoothed deformation scenario, preferably optimal, as described above, by requiring that the tooth model modeling the molar respects the path determined following the deformation scenario determined at step b) and that the instantaneous speed of the tooth model modeling the canine does not exceed the upper limit defined for a canine by more than 10%, at any time. It then searches for a new smoothed deformation scenario, preferably optimal, as described above, by requiring that said tooth models modeling said canine and said molar respect their respective paths determined according to the previous smoothed deformation scenarios and that the speed instantaneous of a tooth model modeling for example an incisor does not exceed, for example, by more than 10% the upper limit defined for an incisor, at any time.

The smoothing can be repeated for each tooth. If smoothing is not successful, the speed constraint, for example limiting the speed variation to less than 10% of the average speed, can be reduced. It is also possible to resume smoothings carried out previously, by reducing the speed constraints for these previous smoothings.

In one embodiment, the computer implements an optimization algorithm in order to test several sets of constraints to be imposed for the elementary deformations, and to deduce an optimally smoothed deformation scenario, that is to say in which the highest values achieved for the speeds of the slowed tooth model are the lowest possible. The amplitude of the range of possible speeds is advantageously reduced to a maximum.

The computer can also or alternatively present the different smoothed deformation scenarios to a dental practitioner so that the latter can choose the smoothed deformation scenario that they prefer. The dental practitioner's selection criteria can also be programmed into the computer so that the computer can choose a deformation scenario.

In step e ), subsequent to step c), and possibly in step d), the intermediate models are used to design and manufacture one or more orthodontic appliances, for example one or more orthodontic aligners. The design can be done by the computer, possibly with a dental practitioner. Manufacturing can be carried out by any suitable manufacturing machine.

As is now clear, the invention makes it possible to carry out a partial or complete orthodontic treatment plan very quickly. Tests have shown that a deformation scenario can be determined by the computer in less than 10 minutes, then broken down by the computer to obtain a good quality treatment plan, which meets the user's requirements. Smoothing speeds also helps limit the risks to the user's health.

Smoothing process

The smoothing process described above can advantageously be generalized to a process comprising steps A) to D), illustrated in the .

In step A), to generate or recover the initial and final models, we preferably proceed following step a).

In step B), the definition of the measured distance for a tooth model can be arbitrary.

For example, after superimposing the initial and final models so that the immobile parts of the arch merge, we can measure
- the Euclidean distance between a point of the initial model, in particular a remarkable point, for example the barycenter, and the corresponding point of the final model;
- the cumulative Euclidean distance between several points, preferably remarkable, of the initial model and the corresponding points of the final model.

A distance resulting from simple measurements measuring the difference in configurations of the tooth model between the initial model and the final model, for example the sum of Euclidean distances between points on the tooth model in the initial model and the corresponding points on the tooth model in the final model, advantageously limits the calculations to find the limiting tooth. In one embodiment, no deformation scenario is determined before the first smoothed deformation scenario.

After having superimposed the initial and final models so that the immobile parts of the arch merge, we can for example measure the distance traveled by one or more points, preferably remarkable, following a basic deformation scenario between the model and the final model, preferably as defined according to the first main aspect of the invention.

The distance traveled for a set of points of the tooth model following a basic deformation scenario, as for step d), is more complex since it requires defining said basic deformation scenario, preferably following a step b ). However, it is more precise and advantageously limits the risk of error when determining the limiting tooth.

The distance measurement is preferably carried out by a computer, independently.

The travel time of the distance for a tooth model can be roughly estimated, for example by dividing the distance measured for a tooth model by a constant speed set for said tooth model. The speed assigned to a tooth model is preferably determined as a function of the number of the tooth modeled and/or as a function of the physiological possibilities of movement of the tooth modeled.

In an advantageous embodiment, the speed assigned to a tooth model is variable depending on the moment considered. In particular, it can increase from the initial instant, for example for more than 5 days from the initial instant, and/or it can decrease as an estimate of the final instant approaches, for example example at least during the 5 days preceding the estimation of the final instant. Preferably, it is lower for times close to the initial time and the estimate of the final time.

Said constant speed may be a speed representative of one or more speeds of movement of one or more points of the tooth model. It can for example be the module of the vector of the translation speed of the barycenter of the tooth model.

The travel time of the distance for a tooth model can be evaluated more finely. For example, the speed of a tooth model can be variable, and in particular depend on the nature of the displacement considered, and therefore depend on the displacement considered during a path of the tooth model between its configurations in the initial and final models. The path of a tooth model can be determined by establishing a basic deformation scenario following step b).

The elementary duration between two successive configurations of the tooth model can for example be determined by dividing the elementary distance traveled by this tooth model between these two configurations by a speed determined for this elementary distance. The duration of travel of the distance measuring the difference between the configurations of the tooth model in the initial model (initial configuration) and in the final model (final configuration) can then be the sum of the elementary durations determined between the different successive configurations since the initial configuration until final configuration.

The duration of the distance travel is preferably carried out by a computer, autonomously, that is to say without human intervention, preferably by the computer which implemented the previous step.

In step C), we then compare the durations determined for each tooth model, then we retain the limiting tooth model, associated with the longest duration. The movement of the limiting tooth that it models sets the shortest possible duration for orthodontic treatment.

The duration associated with the limiting tooth model defines the duration of orthodontic treatment. It can be added to the initial instant in order to define the final instant.

The comparison of durations is preferably carried out by a computer, independently, preferably by the computer which implemented the previous steps.

In a preferred embodiment, for each tooth model and for each type of movement (intrusion/egression, mesialization/distalization, lingualization/vestibularization, tip, torque and rotation) a distance to be covered between the initial configuration and the final configuration, and we divide this distance by the maximum speed. The longest duration determines the limiting tooth pattern.

In step D), the computer determines the first smoothed deformation scenario, preferably so as to reduce, preferably minimize, a said speed parameter.

Preferably, the computer determines the first smoothed deformation scenario so as to reduce, preferably minimize, between the initial instant and the final instant, the greatest value of at least one movement speed reached for at least one tooth model other than the limiting tooth model, or “first idle tooth model”.

The first slow tooth model models a “slowed first tooth”. The first slowed tooth is preferably, among all the teeth modeled in the initial model and apart from the limiting tooth modeled by the limiting tooth model, the tooth of the arch whose speed of movement is the most critical for health of the user, that is to say the tooth whose rapid movement generates the highest risk for the user.
In one embodiment, the computer determines the first smoothed deformation scenario to slow down all tooth models other than the limiting tooth model.

Whatever the embodiment, step D) is preferably repeated by changing each time the tooth model which is slowed down, imposing on each occurrence of step D) that the tooth models having been slowed down during of previous steps D) follow the path defined during these previous steps D), as described for step d).

The order in which the tooth models are successively slowed down is preferably determined according to usefulness criteria defined by the dental practitioner and/or the user.

After step D), the method may include a step e) of design and manufacture of at least one orthodontic appliance, in particular an orthodontic splint, according to the first smoothed orthodontic treatment plan.

In step A), the computer recovers an initial model resulting from a scan of the user's arch, with an optical scanner.

The dental practitioner assisted by the computer, or the computer independently, determines a final model.

In steps B) and C), the dental practitioner assisted by the computer, or the computer autonomously, searches for a basic deformation scenario between the initial and final models as described in step b), that is- i.e. paths for each of the tooth models. Then it determines the limiting tooth model and the final instant according to the paths (to determine the distance traveled) and the kinetic capacities (to determine the duration of travel of the distance) of the tooth models.

Alternatively, the computer-assisted dental practitioner, or the computer autonomously, does not determine a basic deformation scenario, but determines the limiting tooth model by comparing distances between the initial and final configurations of the different tooth models. .

Once the limiting tooth model has been identified, the process preferably tries to make the other tooth models move as slowly as possible.

In step D), the dental practitioner assisted by the computer, or the computer independently, chooses the “slowed down tooth model”, preferably the tooth model whose slowing down is the most useful for health and/or or to meet user requirements.

To determine the first smoothed deformation scenario, the computer searches for a set of successive elementary deformations transforming, by moving tooth models, the initial model at the initial instant into the final model at the final instant, and minimizing the parameter of speed for the slow tooth model. It preferably implements a conventional optimization algorithm, preferably a metaheuristic method, preferably chosen from the methods described above.

The cost function to be minimized may in particular be the greatest speed of movement reached by the slowed tooth model between the initial instant and the final instant. This speed can be determined as being the greatest instantaneous speed between these instants, the instantaneous speed being calculable by dividing a distance between two successive configurations of a tooth model by the time interval between these two configurations.

In a substantially equivalent manner, the optimization can also be carried out by defining the sets of constraints imposed for the elementary deformations so that they all impose that the instantaneous speed (for said speed of movement) between two successive elementary deformations is less than one determined value. The computer then searches for a deformation scenario respecting these sets of constraints then, if successful, reduces said determined value. Iteratively, the computer can thus succeed in determining the lowest possible value for the upper limit of the movement speed between the initial instant and the final instant which makes it possible to define a deformation scenario. This deformation scenario is then a first smoothed deformation scenario.

Preferably, steps D) are then renewed, successively for other slowed tooth models, prioritizing the tooth models whose slowing is the most useful for health and/or to meet the prescriptions of the user.

The intermediate moments can be defined, preferably at the end of the process, depending on the action capabilities of the orthodontic appliance(s) envisaged for the orthodontic treatment.

In a preferred embodiment, when determining a smoothed deformation scenario, configurations are imposed at certain times for tooth models.

In particular, for the determination of the first smoothed deformation scenario, the sets of constraints impose configurations on the limiting tooth model. The imposed configurations are preferably “transition” configurations in transition models of a basic deformation scenario, preferably configurations at intermediate times.

Likewise, for the determination of the second smoothed deformation scenario at the second occurrence of step D), the sets of constraints impose configurations on the limiting tooth model and the first slowed tooth model. The imposed configurations are preferably “transition” configurations in transition models of the first smoothed deformation scenario, preferably configurations at intermediate times. We proceed in a similar manner for the following occurrences of step D).

Preferably, steps B) to D) are carried out autonomously by a computer.

In one embodiment, smoothing is performed to improve an existing orthodontic treatment plan.

A dental technician or practitioner defines an orthodontic treatment plan with a computer, preferably in a conventional way, for example with the Treat software, starting from the initial model, by moving the tooth models from the initial model to a desired configuration at the end of orthodontic treatment. It thus determines the intermediate times, in particular for orthodontic splint changes, the final time and a “conventional” deformation scenario comprising the intermediate models of the dental arch at the intermediate times.

From these data, preferably determined in a conventional manner, the computer can implement steps B) to D), preferably autonomously. The dental practitioner or technician thus has a solution allowing him to perfect the orthodontic treatment plan he has established.

As is now clear, the method according to the invention allows the computer to spread out as much as possible, in the time interval between the initial instant and the final instant, the progression of the tooth models, i.e. that is, to smooth the movement of the tooth models as much as possible by reducing the instantaneous speeds of movement of the tooth models as much as possible.

Of course, the invention is not limited to the embodiments described in detail above.

Claims (14)

Method for defining an orthodontic treatment plan and/or for monitoring the proper progress of orthodontic treatment, said method comprising the following steps:
01) a first user enters first information on a first screen of a computer;
02) the computer analyzes said first information, then prepares and displays, on a second screen of the computer, a form page comprising an input field presenting a request to a second user to enter second information, l display or not of the input field and/or the nature of the second information accepted by the input field depending on the first information entered by the first user in the previous step;
03) the second user enters the second information on the computer using the input field;
04) the computer uses the second information and preferably the first information to define said orthodontic treatment plan and/or to monitor the proper progress of said orthodontic treatment,
the first user may be identical or different from the second user, the first screen may be identical or different from the second screen. Method according to the preceding claim, in which the first information and/or the second information
- define(s) a constraint for orthodontic treatment of the second user, preferably to express a need so that an orthodontic treatment to be planned generates limited pain and/or has a limited duration and/or has a limited cost and/or has a limited aesthetic impact and/or has minimal reliability, and/or involves a limited duration for wearing an orthodontic appliance, and/or achieves a predetermined functional, orthodontic or therapeutic objective, and/or
- is/are an image representing, at least partially, a dental arch of the first user. Method according to any one of the preceding claims, wherein said computer is integrated into a mobile telephone of the second user. Method according to the preceding claim, in which the first user acquires an image, preferably a photo, representing at least part of one of his dental arches with said mobile phone, then enters said image as said first information. Method according to the immediately preceding claim, in which the first user enters said image as first information, then the computer analyzes said image and, depending on the result of said analysis, displays or not the input field and/or determines the nature of the second information accepted by the input field. Method according to any one of the two immediately preceding claims, in which the first user acquires, as said image, at least one closed mouth photo and at least one open mouth photo, preferably at least one closed mouth photo, at least one photo open mouth, at least one photo seen from the front, at least one photo seen from the right and at least one photo seen from the left. Method according to any one of the three immediately preceding claims, in which the first user acquires, as said image, at least one closed-mouth panoramic and/or cephalometric radiograph and at least one open-mouth photo, preferably at least one closed-mouth photo. , at least one open mouth photo, at least one front view photo, at least one right view photo and at least one left view photo Method according to any one of the preceding claims, in which the first information and/or the second information defines a number of teeth to be moved and/or the number of teeth to be moved and/or kept immobile in the frame of an orthodontic treatment plan. Method according to any one of the preceding claims, in which the input field only accepts second information if it belongs to a predefined range or to a predefined list, said range or said list depending on the first information. Method according to any one of the preceding claims, in which the format of the input field depends on the first information. Method according to any one of the preceding claims, in which, as soon as a first piece of information has been entered by the first user, the computer analyzes said information and accordingly adapts the page displayed on said first screen. Method according to any one of the preceding claims, comprising, for each first piece of information of a plurality of first pieces of information, a cycle of steps 01) to 03), displaying or not the input field of a step 02) of a said cycle and/or the nature of the second information accepted by the input field of a step 02) of a said cycle depending not only on the first information entered by the user in step 01) of said cycle, but also at least one first piece of information and/or at least one second piece of information entered during one or more previous cycles. Method according to any one of the preceding claims, wherein the second user is the first user. Computer into which is loaded a program comprising program code instructions for executing a method according to any one of the preceding claims when said program is executed by said computer.