METHOD FOR CONTROLLING THE POSITIONING OF ORTHODONTIC ATTACHMENTS

Abstract

A method for testing an orthodontic appliance comprising a set of brackets fixed to a patient's dental arch, in a first arrangement of the brackets, and a first archwire attached to said brackets, the method comprising the following steps: 1') receiving a first representation of the brackets depicting said brackets in the first arrangement of the brackets; 2') evaluating, by computer, based on the first representation of the brackets, the compatibility of the first arrangement of the brackets with an archwire to be tested, intended to be attached to said brackets after the first archwire; 3') depending on the compatibility, displaying, by the computer, an information message. No abbreviated figure.

Description

Title of the invention: METHOD FOR CONTROLLING THE POSITIONING OF ORTHODONTIC BRACES technical field

[0001] The present invention relates to the control of the positioning of orthodontic brackets, in particular to verify that they are correctly fixed on a patient's teeth or that they are correctly arranged to receive a new orthodontic arch.

[0002] The invention also relates to a computer program as well as a computer and a system for implementing such control. Previous technique

[0003] Orthodontic treatment is intended to modify the arrangement of the teeth of a patient's dental arch, by means of an orthodontic appliance.

[0004] Among orthodontic appliances, a distinction is made between archwire and bracket orthodontic appliances on the one hand, and orthodontic aligners on the other.

[0005] An orthodontic appliance with an archwire and brackets comprises brackets fixed to the teeth and connected to each other by means of an orthodontic archwire, typically made of a shape-memory material, inserted into grooves formed in the brackets. An orthodontic archwire connects teeth to each other and advantageously exerts a rapid action on the movement of these teeth.

[0006] Classically, throughout the treatment, the practitioner uses several different orthodontic arches which he places and removes from the slots of the brackets according to a predefined sequence.

[0007] Treatment typically begins with an initial alignment phase during which the teeth are aligned horizontally and then vertically. The practitioner typically chooses archwires made of a highly flexible alloy, with a small diameter (the diameter of the archwire does not completely fill the slots of the brackets) and a round cross-section.

[0008] During a second phase, the teeth are subjected to torque. For this purpose, subsequent archwires are generally larger in diameter, square or rectangular in cross-section, and made of a more rigid alloy. The last archwire used in orthodontic treatment, that is, the last archwire specified in the orthodontic treatment plan, is called a "full-size" archwire. It is typically sized to fill the bracket slots almost completely. The last archwire is thus mounted with minimal or no play in the slots. It has the greatest mechanical force. strong on the teeth and is intended for a final movement of the teeth towards their alignment at the end of treatment.

[0009] The times for implementing the steps of an orthodontic treatment (times at which the arches must be changed) are generally planned empirically (every 8 weeks on average).

[0010] Classically, an orthodontic treatment plan is drawn up by the dental practitioner. The orthodontic treatment plan defines the sequence of orthodontic arches that he wants to use (materials, section, shape, diameter, manufacturer), the working technique that he practices (MBT, Rickets, etc.), the type of brackets that he uses (position of the bracket, shape of the groove, material, with or without auxiliary devices, manufacturer).

[0011] The orthodontic treatment plan may also define an arrangement of teeth aimed at the end of treatment, and preferably a representation of the teeth thus aligned in the form of a digital model.

[0012] The practitioner can also determine a series of digital models comprising a model representing the patient's arch at the beginning of orthodontic treatment, and a model representing said arch at the end of orthodontic treatment. Unlike aligner treatments, it is difficult to predict one or more intermediate models representing said arch at intermediate times between the beginning and the end of orthodontic treatment, the intermediate times being times at which the archwire in the patient's mouth must be changed.

[0013] However, many discrepancies are observed with respect to the actual state of the patient's dental arch when such a prediction is made at the orthodontic treatment plan design stage. Indeed, it often happens that the practitioner realizes at an advanced stage of treatment that the patient's dental arch does not allow them to proceed to the finishing stage (the final stage of treatment) because one or more brackets have been improperly bonded, impacting the movement of one or more teeth. It is then necessary for the practitioner to modify, or even extend, the standard orthodontic treatment with a corrective phase (for example, the practitioner may modify the configuration of the installed archwire or decide to correct the positioning of one or more brackets).

[0014] Modifying the orthodontic treatment plan, and in particular the correction stage, generally lengthens the duration of orthodontic treatment and is often poorly accepted by the patient.

[0015] There is therefore a permanent need to limit this modification, and in particular to limit the correction steps.

[0016] Furthermore, the practitioner has no way of knowing in advance the opportune moment to change the archwire. He therefore schedules appointments for his patient blindly. These appointments are thus sometimes unnecessary.

[0017] Furthermore, during an appointment, the practitioner may discover that the new archwire, generally more rigid than the old one, cannot be attached to one or more brackets. They must then remove the new archwire from the teeth to which they had begun attaching it, reinstall the previous archwire, and schedule a new appointment with the patient without prior notice. This process results in a considerable loss of time for both the practitioner and the patient. It can lead to disengagement from the patient's treatment.

[0018] There is an ongoing need for a more efficient appointment planning process, in particular for assessing the compatibility of an orthodontic archwire with a set of brackets fixed to the patient's teeth.

[0019] Furthermore, if the new bow cannot be attached to one or more fasteners, it can no longer be used and is discarded without having served its purpose. This results in an environmental and economic cost.

[0020] There is a permanent need to limit this cost.

[0021] One object of the invention is to meet these needs. Summary of the invention

[0022] According to a first principal aspect, the invention proposes a computer program comprising code instructions which, when executed by a computer, carry out a process comprising the following successive steps: a) reception or generation of a first representation of attachments comprising a set of attachment models in a first arrangement of attachment models at a first instant of an orthodontic treatment plan, b) by means of a computer, generation, from the first attachment representation, of a second attachment representation representing said set of attachment models in a second arrangement of attachment models.

[0023] In step b), moving the attachment models involves modifying their position and / or orientation within the arch model. Since the attachments are fixed to their respective anchor teeth, moving an attachment results in the movement of its anchor tooth, and vice versa. “Movement rules” can limit the possibilities for moving the teeth and attachments, and therefore their models.

[0024] The arrangement of the tooth models is referred to as the "second arrangement of tooth models" when the attachment models are in the second arrangement of attachment models.

[0025] The second representation of fasteners can result from a step bl) comprising determining the displacement of said fasteners, from the first instant, under the effect of an arc, called the "second arc", which would be attached to them and optionally of one or more auxiliary devices, for example a chain, until a second instant in the plane of orthodontic treatment, and reproduction of said displacement on said attachment models so as to achieve said second arrangement of attachment models.

[0026] In other words, the effect, on the position and orientation of the attachments, of a second archwire and optionally of one or more auxiliary devices, for example a chain, which would be attached to the attachments modeled by said set of attachment models in the first arrangement of attachment models, is simulated.

[0027] This simulation moves the attachment models to the second arrangement of attachment models as anticipated for a second time within the framework of the orthodontic treatment plan, for example as anticipated at the end of the orthodontic treatment.

[0028] Initially, the brackets may not have an archwire, or they may have a first archwire. In one embodiment, the second archwire is not the one intended to be worn immediately after the first archwire, according to the orthodontic treatment plan. In other words, one or more archwires may be provided between the first and second archwires.

[0029] The second attachment representation can result from a step b2) involving the displacement of the attachment models so as to arrange them according to an arrangement of the target attachment models, constituting said second arrangement of the attachment models.

[0030] The arrangement of the target attachment models can be, for example, an arrangement adapted, or even optimal, to receive the second arch, or an arrangement following the general curvature of the arch bearing the attachments, or a theoretical arrangement, for example to arrange the attachment models in a plane or to align them on a curve.

[0031] Preferably, the second arch is the last arch planned according to the orthodontic treatment plan.

[0032] In the arrangement of the target attachment models, said attachment models are preferably in a common plane, preferably horizontal, and / or aligned along a curve following the general shape of the arch of the fixing teeth, and / or are arranged in accordance with the expected result at the end of a step in the orthodontic treatment plan.

[0033] In one embodiment, - in step a), the first representation of attachments is a first composite model including - a first arch model comprising tooth models representing teeth from a patient's arch in an initial arrangement of said teeth at the first instant; and - the set of attachment models fixed to said respective tooth models, in the first arrangement of the attachment models; and - step b) involves the generation of a second composite model from the first composite model, by moving the tooth models to a second arrangement of teeth, the attachment models remaining virtually fixed to the respective tooth models during said movement and reaching the second arrangement of attachment models in the second composite model.

[0034] The second attachment representation can result from a step b3) in which the first attachment representation is a first composite model comprising tooth models, and in particular models of the attachment teeth.

[0035] The tooth models can be moved so as to arrange them: b31) according to an arrangement of the target tooth models, the arrangement of the attachment models thus obtained constituting said second arrangement of the attachment models.

[0036] The tooth models can be moved so as to arrange them: b32) as a consequence of the movement of the attachments resulting from a step bl) or a step b2). At step b31), the second arrangement of tooth models is preferably such that the tooth models are arranged according to a target tooth model arrangement, preferably corresponding to a target arrangement for teeth at a stage of the orthodontic treatment plan, preferably at the end of orthodontic treatment.

[0037] Preferably, in step b2) or b32), the arrangement of the target attachment models is an arrangement planned in the last step of the orthodontic treatment plan, preferably at the end of said last step.

[0038] In practice, generating an initial composite model is straightforward. Representing the teeth provides the patient or practitioner with a more realistic visualization of the patient's dental arch. However, generally speaking, it is not necessary for the patient's teeth to be represented. Not representing the teeth speeds up computer processing and significantly reduces its cost. Therefore, the initial representation of brackets is not necessarily a first composite model.

[0039] The first representation of attachments may represent the teeth, or a first representation of attachments not representing the teeth may be isolated from a first composite model by any known cutting technique. It may represent only a portion of the attachments, and in particular may not represent the attachments not intended to be used to attach the second archwire, and / or may represent only partially all or part of the attachments.

[0040] The generation of the second composite model may in particular include the following successive operations: - determination of the displacement of the attachment models resulting from the displacement of the models of the teeth to which they are fixed, in order to move from said first arrangement of teeth to said second arrangement of teeth, - application of said displacement of the attachment models so as to determine, from the first arrangement of the attachment models, the second arrangement of the attachment models, and, - generation of the second composite model including the second arch model and all attachment models in said second arrangement of attachment models.

[0041] In particular for a step b31), the second arrangement of the teeth can be provided by a model representing the arch at the end of orthodontic treatment or by an intermediate model of the orthodontic treatment plan.

[0042] By "generation of the second attachment representation", in particular of the second composite model, it is understood that the program includes code instructions which, when executed by a computer, - generate the second attachment representation autonomously, or - provide an interface for the practitioner to carry out the deformation, in particular by moving the tooth models of the first composite model.

[0043] The modification of the arrangement of the tooth models to obtain the second composite model is preferably carried out by the practitioner.

[0044] As will be seen in more detail later in the description, the program generates a representation of the brackets in a second bracket arrangement adapted for analyzing whether the brackets are correctly positioned and oriented. This representation can also be a particularly useful tool for the practitioner to verify the compatibility of the second bracket arrangement with the orthodontic treatment plan. If necessary, the practitioner can modify the first arrangement of the bracket models, particularly before attaching the brackets to the patient's teeth, and / or modify the arrangement of the brackets themselves if they have already been attached. In particular, the practitioner can modify the position, and especially the height, and / or the orientation of one or more bracket models and / or modify one or more brackets.

[0045] Preferably, the process further comprises, after step b), a step c) allowing the determination of the conformity of the second arrangement of the attachment models, that is to say a verification of the acceptability of this arrangement with regard to the orthodontic treatment plan.

[0046] In one embodiment, step c) is a step cl) in which the computer presents the second attachment representation to a practitioner, preferably presents him with a second composite model, so that he may determine said conformity.

[0047] In one embodiment, step c) is a step c2) in which the computer itself determines said conformity of the second arrangement of the attachment models, and then generates information expressing said conformity, for example a message and / or a visual indication on the first attachment representation and / or on the second attachment representation. Regardless of the method of implementation, said conformity may be: - the suitability of the second arrangement of the attachment models and / or, after step b3), the suitability of the second arrangement of the tooth models, with the orthodontic treatment plan, a suitability to the orthodontic treatment plan including the possibility of achieving a target patient tooth arrangement at the end of orthodontic treatment and / or the possibility of fixing the second archwire to the brackets arranged as in the second arrangement of the attachment models, in particular after step b3), when the fixed teeth are arranged as in the target tooth model arrangement; and / or, - the physiological possibility of moving the fixation teeth so that the attachments are arranged as in the second arrangement of the attachment models.

[0048] In one embodiment, - Determining the suitability of the second arrangement of the bracket models with the orthodontic treatment plan involves comparing the position and / or orientation of at least one bracket model, preferably of each bracket model, with a predefined bracket position range and / or a predefined bracket orientation range, respectively. Conformity is granted or rejected depending on whether said position and / or orientation falls within the predefined bracket position range and / or the predefined bracket orientation range, respectively. The predefined bracket position and orientation ranges may, in particular, be defined with regard to aesthetic and / or orthodontic standards; and / or - after step b3), the determination of the suitability of the second arrangement of the attachment models with the orthodontic treatment plan, includes a comparison of the position and / or orientation of at least one tooth model, preferably of each tooth model, with a predefined tooth position range and / or a predefined tooth orientation range, respectively, conformity being acquired or rejected depending on whether said position and / or said orientation belongs to the predefined tooth position range and / or the predefined tooth orientation range, respectively, the predefined tooth position and orientation ranges being able in particular to be defined with regard to aesthetic and / or orthodontic standards;and / or - after step b3), the determination of the possibility of fixing the second arch on the fixation teeth arranged as in the arrangement of the target tooth models involves a comparison of at least one parameter of the second arch, in particular; chosen from one or more dimensions of the arc, in particular the diameter of the arc section, the constitutive material of the arc, the shape of the arc section, and a combination of these parameters, with the second arrangement of attachment models, while the tooth models are in the arrangement of target tooth models.

[0049] In one embodiment, - determining the suitability of the second arrangement of attachment models with the orthodontic treatment plan involves comparing the second arrangement of attachment models with an arrangement of attachment models targeted at the second time, preferably with an arrangement of attachment models targeted or anticipated at the end of the orthodontic treatment; - said verification of the physiological possibility of moving the fixation teeth includes, after step b3), a verification of dental crowding, (for example: verification of the absence of interpenetration of tooth models, of the need to expose teeth or to perform stripping) and / or a comparison of the position and / or orientation of at least one, preferably of each tooth model, with a predefined tooth position range and / or a predefined tooth orientation range, respectively; - after step b3), the determination of the possibility of fixing the second arch on the fixing teeth arranged as according to the arrangement of the target tooth models, involves a comparison of a maximum stress along the second arch with a predefined threshold stress.

[0050] Preferably, the process further comprises, after step c), a subsequent step d): d) in case of non-conformity, i.e. in the absence of conformity, dl) - modification - the position and / or orientation of at least one bracket model in the first bracket representation, optionally in the first composite model, and / or - the orthodontic treatment plan, preferably by modifying the duration of a step in the orthodontic treatment plan; and / or - presentation, to a practitioner, of information expressing said non-conformity so that said practitioner may modify - the position and / or orientation of at least one attachment model in the first attachment representation, and / or - the position and / or orientation of at least one bracket fixed to a tooth of the patient, and / or - the orthodontic treatment plan, for example by modifying at least one archwire planned, according to the orthodontic treatment plan, to be attached to the brackets after the first moment or by modifying the times at which the steps must be carried out (modification of scheduled appointments with the patient),

[0051] and d2) optionally, generation of instructions for the manufacture and / or preparation and / or ordering of a fastener transfer tray.

[0052] The information expressing said non-conformity, preferably in writing or sound, may be, for example, a display of a message on a computer screen.

[0053] In one embodiment, the cycle of steps a) to d) is repeated with different initial arrangements of the attachment models, until conformity is observed in step c) or for simulation purposes. If step d) involves presenting the practitioner with the first representation of attachments, preferably the first composite model, so that he can make said modification, step a) is not resumed until after the practitioner has made this modification.

[0054] If the cycle is carried out autonomously by the computer, the choice of the current arrangements of the attachment models at each new cycle can be guided by an optimization algorithm, known per se.

[0055] In a preferred embodiment, the cycle of steps a) to d) is repeated, modifying the first arrangement of the attachment models at each cycle.

[0056] The first moment is preferably at the first stage of the orthodontic treatment plan or before the first stage of the orthodontic treatment plan.

[0057] In a preferred embodiment, the first moment is at the first stage of the orthodontic treatment plan or before the first stage of the orthodontic treatment plan and / or the second arrangement of brackets is an arrangement aimed at the last stage of the orthodontic treatment plan.

[0058] Preferably, the process comprises - a step b2), the second arch being the last arch planned according to the orthodontic treatment plan, the arrangement of the target attachment models being such that said attachment models are in a common plane, preferably horizontal, and / or aligned along a curve following the general shape of the arch of the fixing teeth, and / or are arranged in accordance with the expected result at the end of a step of the orthodontic treatment plan; - a determination of conformity by verifying the possibility of fixing the second arch on the fixing teeth arranged as per the arrangement of the target tooth models; - at least in the event of non-compliance, a presentation to a practitioner of information expressing said non-compliance.

[0059] The invention also relates to a method for controlling the positioning and / or orientation of a set of orthodontic brackets, said brackets being fixed or intended to be fixed to teeth of a patient's arch, said method comprising the following successive steps: 1) reception or generation, at a first instant, by computer, of a first representation of attachments comprising a set of attachment models in a first arrangement of attachment models, preferably a first composite model including - a first arch model comprising tooth models representing teeth of said arch in a first arrangement of teeth at the first instant; and - a set of attachment models fixed onto said respective tooth models, in a first arrangement of attachment models; 2) implementation of steps a) and b) of a program according to the invention so as to generate a second representation of fasteners, optionally a second composite model, step a) consisting of retrieving the first representation of fasteners, optionally the first composite model, generated in step 1); 3) implementation of a step c) of a program according to the invention and / or human determination, preferably by a dental practitioner, of said conformity; 4) - implementation of step d) of a program according to the invention; and / or - in case of non-conformity, human modification, preferably by a dental practitioner, using a computer, - the position and / or orientation of at least one bracket model in the first bracket representation, preferably in the first composite model, and / or - the orthodontic treatment plan, preferably of one or more arches and / or arch models intended to be worn by the patient after the first instant; and / or - modification, preferably by a practitioner, of the arrangement of brackets on the arch when the brackets have been, prior to the first instant, fixed to the patient's teeth.

[0060] Preferably, in step 1), the first composite model is generated: i) by adding attachment models to the first arch model; or ii) by scanning the patient's arch on which attachments have been previously fixed; or iii) by updating a previous composite model generated at an earlier time.

[0061] In embodiment i), adding attachment models to the first arch model means virtually fixing said attachment models onto tooth models, modeling attachment teeth, of the first arch model. After its virtual fixing, each attachment model retains its position and orientation relative to the tooth model on which it is fixed, so that the movement of the tooth model to obtain the second composite model entails that of the attachment model.

[0062] The addition of the attachment models to the first arch model is preferably carried out by the practitioner using a computer. Software for such additions is well known. The attachment models may be models supplied by the attachment manufacturers.

[0063] This embodiment is particularly suitable when the first instant is different from the start of treatment.

[0064] Preferably, before adding attachment models to the first arch model, the first arch model is generated by scanning the patient's arch on which attachments have not yet been fixed or by updating a previous model of said arch, following these steps: - we generate an "anterior" model of said arch at an "anterior instant" prior to the first instant, preferably at the beginning or before the orthodontic treatment; - the anterior arch model is divided into tooth models using a computer; - At the first moment, a person, preferably the patient, takes at least one photograph of said dental arch, preferably with their mobile phone, and transmits said at least one photograph to a computer having access to the cut-out anterior dental arch model; then the arrangement of the tooth models of the cut-out anterior dental arch model is modified, preferably by computer, to position said tooth models as shown in said at least one photograph, so as to obtain the first dental arch model. This modification is preferably carried out autonomously by said computer, as described, for example, in EPI8184486.

[0065] Preferably, the anterior arch model is generated - by scanning, at the previous moment, the patient's arch or a physical model of said arch, or - by assembling historical tooth models according to an anterior arrangement of teeth as represented on at least one photograph of the arch acquired at the previous moment, preferably by the patient.

[0066] The choice of historical tooth models and their assembly are preferably carried out by a computer, as described for example in patent application EP18184486.

[0067] In embodiment ii), when scanning the patient's arch on which brackets have been previously fixed, the first arch model and said set of bracket models in the first arrangement of bracket models are generated simultaneously.

[0068] The cutting of the first composite model then does not need to distinguish the attachment models from the tooth models. Preferably, the first The composite model consists of composite tooth models, each representing a model of a fixed tooth and, for fixed teeth, an attachment model. The single division into composite tooth models may be sufficient to perform step b): the movement of the tooth models to the second tooth arrangement is achieved by moving the composite tooth models.

[0069] The first composite model is divided into tooth models. If the tooth models are composite, that is, if they incorporate the attachment models, then it is the composite tooth models that are displaced. The displacement of a composite tooth model is considered a special case of tooth model displacement.

[0070] The first moment can be in particular the start of treatment, the first composite model being generated on the day the practitioner glues the brackets onto the fixation teeth.

[0071] In embodiment iii), the first composite model is generated by updating a previous composite model, following the following steps: - a "previous" composite model of said arch is generated at a "previous instant" prior to the first instant, preferably at the beginning or before orthodontic treatment, preferably according to embodiments i) or ii); - The anterior composite model is computer-cut into composite tooth models, each composite tooth model representing an attachment model, and the model of the tooth to which the attachment represented by the attachment model is fixed; - Initially, a person, preferably the patient, takes at least one photograph of said dental arch, preferably with their mobile phone, and transmits said photograph to a computer with access to the cut anterior composite model; then, the arrangement of the composite tooth models in the cut anterior composite model is modified to position said tooth models as shown in said photograph, so as to obtain the first composite model. This modification is preferably performed autonomously by said computer, as described, for example, in patent application EPI8184486.

[0072] The method can be implemented while the orthodontic treatment plan is being carried out, i.e., when the brackets are fixed to the patient's dental arch teeth, with a first archwire being fixed to the brackets. In step 1), the first arch model can, in particular, be an arch model from the beginning of the first stage of orthodontic treatment.

[0073] Steps 1) and 2), and preferably 3) or 4), and preferably 3) and 4), can be implemented by a computer programmed by means of a program according to the invention. In particular, the program may include code instructions to implement step 1).

[0074] The characteristics of an object described for the computer program are applicable to the same object described for the process, and vice versa.

[0075] According to a second main aspect, the invention relates to a method of controlling an orthodontic appliance worn by a patient as part of orthodontic treatment, the orthodontic appliance comprising a set of brackets fixed to a dental arch of a patient, in a first arrangement of the brackets, and a first arch attached to said brackets, the method comprising the following steps: 1') receiving or generating a first representation of brackets representing said brackets in the first arrangement of brackets; 2') evaluation, by computer, from the first representation of attachments, of the compatibility of the first arrangement of attachments with a bow to be tested intended to be attached to said attachments; 3') depending on compatibility, presentation, by the computer, of an information message, preferably at least to the patient and / or the practitioner implementing the orthodontic treatment, the message preferably giving indications on compatibility and / or on a step of orthodontic treatment which depends on compatibility.

[0076] The information message may indicate whether the orthodontic appliance worn by the patient should be maintained, and / or checked and / or modified.

[0077] Preferably, said arch to be tested is a future arch intended to be attached to said brackets after the first arch, according to the chronology defined by the orthodontic treatment plan.

[0078] Advantageously, the compatibility is binary, or "Boolean", that is to say, it can only take two values ​​corresponding to compatibility and incompatibility.

[0079] Preferably, the process includes, after step 3'), a subsequent step 4'): 4') only in case of compatibility, scheduling an appointment with the patient and / or checking and / or modifying the orthodontic appliance worn by the patient.

[0080] The control, carried out at a first instant, preferably at a current instant, makes it possible to plan accordingly an intervention on the orthodontic appliance and / or manufacture an arch intended to replace an arch worn by the patient.

[0081] At the first moment, the brackets are already fixed to the patient's teeth and a first archwire is attached to them. One objective is, before manufacturing, ordering or preparing the archwire to be tested and / or scheduling an appointment, in particular to attach it to the brackets, to verify its compatibility with the arrangement of the brackets at the first moment, or "first bracket arrangement".

[0082] As will be seen in more detail later in the description, the verification of the compatibility of the arc to be tested with the current arrangement of the attachments is advantageously very precise. Furthermore, the generation of the first representation Using attachments, optionally a first composite model, from a scan or photos (possibly extracted from a video) acquired by the patient, eliminates the need for the patient to travel to the practitioner's office. The patient only visits the practitioner when their current archwire (the first one) needs to be replaced with the test archwire, or when the practitioner requires adjustments to the appliance to resolve a problem preventing the transition to the next archwire. Furthermore, the fabrication of the test archwire, particularly in the rare cases of custom-made archwires, as well as the ordering or preparation of the test archwire, can be initiated only if it is compatible with the current attachment arrangement.

[0083] Preferably, in step 2'), the highest value of a mechanical stress along the arc under test, experienced by the arc under test when it is attached to said brackets in the service position, is determined by computer from the first representation of the attachments, optionally from the first composite model, and from information on the mechanical properties of the arc to be tested. This highest value is preferably the highest value of a mechanical stress along the arc under test experienced by the arc under test when it is deformed from a rest configuration to said service configuration. This highest value is referred to as the "maximum stress." Then, the compatibility is determined by computer from the difference between said maximum stress and a threshold stress. For example, compatibility may be recognized if said difference is less than a threshold value.

[0084] In one embodiment, in step 4'), said modification of the orthodontic appliance worn by the patient includes - a replacement of the first bow with the bow to be tested, after optionally modifying the bow to be tested, optionally without attaching the bow to all the attachments, or a modification of the first bow, for example by bending, and / or of the position of the first bow and / or of one or more attachments and / or of the position and / or orientation of one or more attachments; and / or - the fixing of one or more additional attachments and / or an auxiliary device, and / or an intervention on the patient's teeth, for example to modify their shape, and / or on an auxiliary device, for example a chain, worn by the patient.

[0085] In one embodiment, the first representation of attachments is one or more images, preferably at least one photo acquired by the patient, preferably with his phone, or is a three-dimensional model, preferably obtained by deformation, using a computer, of a previous model.

[0086] The invention also relates to a program comprising code instructions for implementing a method according to the second main aspect, as well as a computer in which such a program is loaded, and in particular to implement steps 1') to 3'), and preferably 4').

[0087] The invention also relates to a system for implementing a method according to the invention, the system comprising: - preferably a device for acquiring a scan, photos and / or video, for step a) or 1) or 1'), preferably a phone, and - a computer programmed to implement step a) or 1) or 1'), and / or step b) or 2), and / or step c) or 3) or 2'), and / or step d) or 3'), and / or step 4'). Definitions

[0088] By "patient" is meant any person for whom a process according to the invention is implemented, in particular a patient.

[0089] The term “practitioner” or “dental practitioner” means any dental practitioner in the broadest sense, which includes in particular orthodontists, dentists and assistants of orthodontists or dentists trained to install an orthodontic archwire or other auxiliary devices in the patient’s mouth.

[0090] The term "installer" means any person competent to install an orthodontic archwire in the patient's mouth. The installer may be a practitioner, an assistant, or, in one embodiment, the patient himself.

[0091] “Orthodontic treatment” is treatment intended to correct the arrangement of the teeth in a dental arch to a final position desired by the patient. Orthodontic treatment requires the maintenance of several orthodontic archwires successively attached to teeth in the arch, called “fixing teeth.” Retention treatment intended to maintain teeth in a final position is not considered orthodontic treatment here.

[0092] In one embodiment, the fixation teeth are incisors and / or canines numbered 11, 12, 13 and 21, 22, 23, collectively referred to as "social six".

[0093] Orthodontic treatment is planned using a "treatment plan." A distinction is thus made between "orthodontic treatment," which refers to a series of operations that take place in practice, and the "treatment plan," which is the result of the design of the orthodontic treatment. The treatment plan therefore precedes the corresponding orthodontic treatment.

[0094] The orthodontic treatment plan defines, for each stage, an archwire to be attached to the brackets and, in particular, may define its shape(s), its constituent material(s), its cross-section(s) (in the case of multi-section archwires), its diameter(s), and its manufacturer. It may also specify the times at which the archwires must be attached, the treatment technique to be applied (for example, MBT, Rickets...). Finally, it may define the parameters of the brackets to be used (types of brackets), in particular: the type(s) of fixation (for example, ligating, self-ligating...), the or the constituent material(s) (e.g., metal, ceramic, sapphire...), the morphology and / or dimensions of the attachment slot, the manufacturer, and their arrangement. The treatment plan may also include the use of auxiliary devices.

[0095] Classically, the arch becomes increasingly rigid as the stage approaches the end of orthodontic treatment.

[0096] Conventionally, brackets are fixed to the fixation teeth during the initial stage of orthodontic treatment in a bracket arrangement adapted to attach the archwire intended for that stage. The shape of the archwire and the position of the brackets are determined so that, in the service position, the orthodontic appliance exerts forces tending to move the treated teeth from their initial arrangement at the beginning of that stage to their final arrangement at the end of that stage.

[0097] In one embodiment, the orthodontic treatment plan can provide, for each stage, an initial arch model representing the arch at the beginning of the stage and a final arch model representing the arch at the end of the stage. The final arch model is a digital model representing the patient's teeth in their arrangement on the dental arch as desired at the end of the stage. The final arch model typically results from a deformation of the initial arch model by moving tooth models. It can typically be determined by a 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. US5975893A also describes the creation of a treatment plan.

[0098] In one embodiment, the orthodontic treatment plan may provide, for each stage, predefined bracket position and / or orientation ranges and / or predefined tooth position and / or orientation ranges. These position and orientation ranges may be relative (e.g., the position of a tooth and / or bracket in relation to another tooth and / or bracket) or absolute. The bracket position and orientation ranges may, in particular, be defined with regard to aesthetic and / or orthodontic standards. Aesthetic standards refer to criteria or principles used to evaluate the beauty and harmony of the smile and face after orthodontic treatment.These standards vary according to cultures (countries, for example) and personal preferences (of the patient or practitioner, for example), but certain principles are generally recognized in the field of orthodontics to optimize both appearance and function. Several parameters can impact the aesthetics of the smile, for example, the type of bracket chosen for treatment, the positioning of the brackets, the orthodontic technique used, and a combination of these parameters.

[0099] The practitioner thus defines, for each stage, an initial arch model and a final arch model, and associates with the stage an arch which he considers appropriate to modify the arrangement of the teeth from the initial arch model to the final arch model.

[0100] An "orthodontic appliance" is an appliance adapted for the implementation of orthodontic treatment. An orthodontic appliance may be intended for therapeutic or prophylactic treatment, but also for aesthetic treatment.

[0101] An orthodontic appliance is here an archwire and bracket appliance. The configuration of an orthodontic appliance can be determined in particular to ensure its fixation to the teeth, but also according to a desired positioning of the teeth.

[0102] Unless otherwise specified, "arch" means an orthodontic arch.

[0103] An “auxiliary appliance” is an appliance used to help move teeth in addition to orthodontic appliances. Examples include chains, springs, screws, or elastics.

[0104] A bow is "attached" to a fastener when the fastener changes the shape of the bow. The fastener may be rigid or not. For example, the bow may be free to slide in the groove of a fastener.

[0105] The "fixation" of an attachment to a tooth is a rigid fixation, conventionally by bonding. The pre-positioning of an attachment is considered a fixation of the attachment.

[0106] The "resting shape" of a bow is its shape before it is attached to the teeth.

[0107] A "fastener arrangement" defined in space, for each said fastener, the position and orientation of the attachment. It can preferably be measured on a 3D model or on photos of the arch bearing these attachments.

[0108] A "tooth arrangement" defines in space, for each said tooth, a position and an orientation of the tooth. It can preferably be measured on a 3D model of an arch bearing these teeth.

[0109] An arrangement of brackets, or a set of bracket designs, is "compliant" when it is suitable for the implementation of the orthodontic treatment plan.

[0110] Such conformity implies that the positions and orientations of these fasteners on the fixing teeth, or of these fastener models on the models of the fixing teeth, respectively, are correct.

[0111] In a preferred embodiment of the first main aspect, conformity of a bracket arrangement is assumed provided that an archwire, for example the full-size archwire, can be fixed to the brackets in at least one arrangement, preferably at least - in the first bracket arrangement, preferably the bracket arrangement at the end of orthodontic treatment, and / or - in the second bracket arrangement, preferably the bracket arrangement at the end of orthodontic treatment, in order to modify the position of the teeth in the arch according to the orthodontic treatment plan.

[0112] In one embodiment of the first main aspect, when the second instant is at the beginning of a stage, and in particular at the beginning of the last stage of orthodontic treatment, conformity can be considered to have been achieved if the second arch can be fixed in the arrangement of brackets at the second instant and is capable of leading to a determined arrangement for the end of said stage.

[0113] In one embodiment of the first main aspect, conformity is admitted as soon as an arch, for example the full-size arch, the arch to be tested can be virtually fixed on the attachment models in at least one arrangement of the attachment models, preferably at least in the first arrangement of the attachment models and / or in the second arrangement of the attachment models, being virtually active in accordance with the orthodontic treatment plan.

[0114] In an embodiment of the second main aspect, the conformity of the arch to be tested, for example a future arch, is admitted if the arch to be tested can be virtually fixed on the attachment models while being virtually active in accordance with the orthodontic treatment plan.

[0115] There is no compatibility, for example, in the event of breakage of the arch in service or during its assembly, breakage or detachment of a fastener, or plastic deformation of the arch or fasteners which would be incompatible with the desired action on the teeth.

[0116] When a set of fasteners or a set of fastener patterns are in a conforming arrangement, said set of fasteners or fastener patterns is said to be "compatible" with the bow in question.

[0117] A 3D scanner, or "scanner", is a device that allows obtaining a model of a dental arch, that is to say a "scan" of this arch.

[0118] The "service position" is the position of an archwire when it has been attached to brackets fixed to the fixation teeth of a patient's dental arch. The "service configuration" of an archwire is the shape it assumes in the service position.

[0119] The term "computer" refers to a computing unit, which includes a set of several machines having computing capabilities. This unit may, 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 patient, for example the "cloud" or a computer located at a practitioner's office.

[0120] Typically, a computer includes, in particular, a processor, memory, a human-machine interface typically comprising a screen, and a communication module for internet, Wi-Fi, Bluetooth®, or telephone network connections. A computer program configured to implement, at least partially, the invention is loaded into the computer's memory. The computer may also be connected to a printer.

[0121] Different computers communicating with each other may be implemented for different stages, or, preferably, the same computer is implemented for all stages.

[0122] The term "model" means a digital model. A model can be three-dimensional or two-dimensional. It is preferably three-dimensional. A three-dimensional model consists of a set of voxels, or "points." A model can be, for example, of the type .stl or .Obj, .DXF 3D, IGES, STEP, VDA, or a point cloud. Advantageously, such a model, called a "3D" model, can be viewed from any angle.

[0123] A model "includes" another model when that other model is an integral part of it. For example, the cut arch model includes the tooth models. The first composite model includes the first arch model and all the attachment models.

[0124] Unless otherwise specified, a "representation" of an object is a computer object that digitally represents that object in several dimensions.

[0125] A model or image, particularly a photograph, "represents" an object when it partially or completely represents that object. In particular, an arch model or photograph may represent only a portion of the teeth in the arch. In one embodiment, a tooth model or a bracket model completely represents the corresponding tooth or bracket.

[0126] A model, in particular a first composite anterior model or an anterior arch model, can be created using professional equipment, for example, a 3D scanner, preferably operated by a practitioner, for example, an orthodontist or an orthodontic laboratory. In an orthodontic practice, the patient or a physical model of their teeth can advantageously be positioned precisely, and the professional equipment can be further refined. This results in a highly accurate model. The model preferably provides information on tooth positioning with an error of less than 0.5 mm, preferably less than 0.3 mm, preferably less than 0.1 mm. The number of points in the 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 anterior model may be slowed down if the number of points is high.

[0127] In one embodiment, the model comprises fewer than 5,000 points, or even fewer than 1,000 points, which speeds up the implementation of the process. In particular, it can result from a simplification of a finer model, preferably acquired with a 3D scanner, for example comprising more than 10,000 or 20,000 points.

[0128] A "model of an arch" is a digital model that represents an arrangement of a patient's teeth, preferably at least all the teeth of at least one arch. Preferably, the model of an arch also represents other organs of the mouth, and in particular the gums.

[0129] The number of points in an arch model is not limited. In one embodiment, an arch model includes only the points strictly necessary for defining the arrangement of the teeth.

[0130] A "tooth model" is a digital model of a tooth in a patient's dental arch. A dental arch model can be segmented to define tooth models for at least some of the teeth, preferably for all the teeth represented in the arch model. The tooth models are thus models within the arch model. Figure 3 shows an example view of an arch model segmented into tooth models, with only the tooth models shown. Computer tools exist for manipulating the tooth models within an arch model. These tools allow constraints to be imposed, particularly to limit the movement of the tooth models to realistic ranges, for example, to prevent adjacent tooth models from interpenetrating.

[0131] A "fastener model" is a digital model of a fastener.

[0132] A bracket can be represented faithfully to reality, the entire bracket being represented, preferably in a hyperrealistic manner, that is to say, with a rendering equivalent to that of a photograph. Advantageously, the arrangement of the brackets is easier to visualize and analyze. Remote monitoring is improved. This also results in an educational benefit for the patient.

[0133] Fastener models may, in particular, be supplied by fastener manufacturers.

[0134] A fastener may also be represented partially or symbolically. Preferably, only certain regions of the attachment can be represented faithfully or hyperrealistically, or symbolically. This has the advantage of speeding up computer processing and saving computing resources.

[0135] The number of points in a tooth or attachment model is not limited. In one embodiment, a tooth or attachment model includes only the points strictly necessary to define its configuration.

[0136] An "anchoring zone" is constituted, for a fastener, by all the surfaces of that fastener which, in the service position, are in contact with an arc. An area The anchorage area can be defined broadly or precisely. Each bracket design defines an anchorage area for the bracket. Generally, the anchorage area is the surface of a groove that receives the orthodontic archwire.

[0137] The "slicing" of an arch model into "tooth models" is an operation that allows the representations of teeth (tooth models) within the arch model to be delimited and made autonomous. Computer tools exist for manipulating the tooth models of an arch model. One example of software for manipulating tooth models is the Treat program, described on the page https: / / en.wikipedia.org / wiki / Clear_aligners#cite_note-invisalignsystem-10.

[0138] When an arch model is cut into tooth models, it is also possible to cut other models, for example a gum model.

[0139] The “configuration” of an object, in particular of a tooth, a tooth model, a fastener or a fastener model, refers to the position and orientation of that object in space.

[0140] By "image" is meant a two-dimensional image, such as a photograph, possibly extracted from a film. An image is made up of pixels.

[0141] The term “image of an arch,” “photograph of an arch,” “view of an arch,” “representation of an arch,” “scan of an arch,” or “model of an arch” means an image, photograph, view, representation, scan, or model of all or part of said dental arch, preferably representing at least 2, preferably at least 3, and preferably at least 4 teeth. [Fig. 2] shows an example of a view of an arch model comprising 5000 points.

[0142] The adjectives "first" and "second" are used for clarity, to easily distinguish the objects they describe. When they refer to first and second moments, these moments follow each other chronologically, the second moment being subsequent to the first. The time interval between these moments is not limited, unless otherwise specified. Some embodiments of the invention, however, do not refer to a second moment.

[0143] The "first arch" is generally an arch worn by the patient at the first moment. The "second arch" is generally the arch that is optionally used to simulate all or part of the orthodontic treatment. The future arch is an arch intended to be worn by the patient while the attachment models are—in their second arrangement, particularly in an embodiment according to the first principal aspect, or - in their first arrangement, in particular in a mode of realization according to the second main aspect.

[0144] “Previous” refers to a moment prior to the first moment.

[0145] The first instant can be, in particular, a current instant or a previous instant. The current instant is the instant at which the process in question is implemented.

[0146] The second instant can, in particular, be a future instant, that is to say, subsequent to the current instant. This embodiment is particularly advantageous when the first instant is a current instant. The invention then makes it possible, in particular, to verify, at any stage of ongoing orthodontic treatment, whether the current bracket arrangement is compliant, and in particular compatible with an archwire planned for a future stage of orthodontic treatment.

[0147] The second instant can, in particular, be a current instant, the first instant being a time prior to the current instant. The prior instant can, in particular, be a time at which the brackets were fixed to the fixation teeth, the current instant being during orthodontic treatment. The invention thus makes it possible, in particular, to verify, at any stage of the ongoing orthodontic treatment, whether the brackets have been fixed correctly.

[0148] When the computer program is implemented at a current moment, "future" therefore refers to a theoretical situation, "anticipated for the future moment", that is to say, as it is predicted at the future moment.

[0149] A “real” or “virtual” object is a physical object, for example a tooth, or a non-physical object, for example a model of a tooth, respectively.

[0150] “Understand”, “include” or “present” must be interpreted in such a way broad, non-limiting, unless otherwise indicated. Brief description of the drawings

[0151] Other features and advantages of the invention will become apparent from the reading of the detailed description which follows and from the examination of the attached drawing in which: - [Fig.1] the [Fig.1] schematically illustrates methods according to the invention; - [Fig.2] [Fig.2] represents an example of an arch model with 5000 points; - [Fig.3] [Fig.3] represents an example of an arch model cut into tooth models, referenced 32 (only the tooth models are shown); - [Fig.4] [Fig.4] represents an example of attachment model representation; - [Fig.5] [Fig.5] represents in perspective an example of a composite model in which the attachment models have been arranged to be aligned and oriented along a curve extending in a plane and following the general curvature of the arch; - [Fig.6] [Fig.6] represents front view, another example of a composite model in which the attachment models have been arranged to be aligned and oriented along a curve extending in a plane and following the general curvature of the arch.

[0152] Further details and advantages of the invention are provided in the detailed description that follows, which is provided for illustrative and not limiting purposes. Detailed description

[0153] First main aspect: control of the arrangement of the fasteners or fastener patterns

[0154] An example of the realization of the first main aspect is now described.

[0155] The control consists of verifying the conformity of a first arrangement of attachment models with regard to an orthodontic treatment plan.

[0156] The method may include generating the orthodontic treatment plan. All known methods for generating an orthodontic treatment plan may be implemented.

[0157] The patient-specific orthodontic treatment plan determines a sequence of archwires to be worn successively by the patient and, preferably, a schedule setting out the periods for wearing each archwire, each period corresponding to a "stage" of treatment. It also determines the objective of the orthodontic treatment, that is, the desired tooth positions and orientations at the end of the orthodontic treatment.

[0158] The orthodontic treatment plan defines, for each stage, an archwire to be attached to the brackets and, in particular, its shape(s) and / or its constituent material(s) and / or its cross-section(s) (in the case of multi-section archwires) and / or its diameter(s), and / or its manufacturer. It may also specify the times at which the archwires should be attached, the treatment technique to be applied (for example, MBT, Rickets...). Finally, it may define the parameters of the brackets to be used (types of brackets), in particular: the type(s) of fixation (for example, ligating, self-ligating...), the constituent material(s) (for example, metal, ceramic, sapphire...), the morphology and / or dimensions of the attachment slot, the manufacturer, as well as their arrangement. The treatment plan may also include the use of auxiliary appliances.

[0159] In one embodiment, the orthodontic treatment plan can provide, for each stage, an initial arch model representing the arch at the beginning of the stage and a final arch model representing the arch at the end of the stage. The final arch model is a digital model representing the patient's teeth in their arrangement on the dental arch as desired at the end of the stage. The final arch model typically results from a deformation of the initial arch model by moving tooth models. It can typically be determined by a 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. US5975893A also describes the creation of a treatment plan.

[0160] In one embodiment, the orthodontic treatment plan may optionally provide, for each step, attachment position and / or orientation ranges Predefined ranges of tooth position and / or orientation. These ranges of position and orientation can be relative (for example, the position and / or orientation of one tooth in relation to another, the position and / or orientation of an attachment in relation to a tooth, the position and / or orientation of one attachment in relation to another, etc.) or absolute. Attachment position and orientation ranges can be defined, in particular, with regard to aesthetic and / or orthodontic standards.

[0161] In step 1), the process includes receiving or generating, at a first instant, by computer, a first representation of attachments comprising a set of attachment models in a first arrangement of attachment models.

[0162] The first representation of attachments is a model representing the position and orientation of each attachment in space at the first instant. The first representation of attachments may be a composite model further representing the dental arch to the teeth of which the attachments are fixed.

[0163] In one embodiment, computer models representing the brackets, and preferably the teeth, are generated. Preferably, this generation is performed at least at the beginning of each step, as well as at the end of the orthodontic treatment, the model at the end of one step typically being the model at the beginning of the next. Each of these models can serve as the initial representation of the brackets. Preferably, the model used at the beginning of the step that initiates the orthodontic treatment is used.

[0164] The first moment, preferably a current moment, is preferably during the initial stage of the orthodontic treatment plan, in particular at the beginning of this first stage. The procedure then allows for early correction of the position and / or orientation of a bracket. The first moment is preferably the moment at which steps b) and c) are implemented. The patient can wear a first archwire at the first moment.

[0165] The first moment may be before the start of treatment, i.e. when the brackets are not fixed to the patient's teeth and / or the first archwire is not attached to the brackets.

[0166] The second instant can be any instant subsequent to the first instant, preferably subsequent to the first stage of treatment, preferably at the beginning or end of a stage subsequent to the first stage, preferably at the beginning or end of the last stage of orthodontic treatment. The stage of orthodontic treatment that contains the second instant is called the "second stage". Preferably, at least one, preferably at least two, preferably at least three intermediate stages separate the first and second instants, and therefore the first and second stages.

[0167] The second stage can in particular be the last stage of the orthodontic treatment plan, the second arch therefore being the last arch planned in the treatment plan, usually a full-size arch.

[0168] First representation of fasteners and first composite model

[0169] The following description refers to a first composite model, but can be generalized to any first representation of attachments, in particular to any first representation of attachments not including a representation of teeth. Except in cases of technical incompatibility, the features described below for the first composite model, even if optional, are applicable to any first representation of attachments.

[0170] The first composite model can represent a real-life situation, with the brackets being brackets actually fixed to the patient's teeth. It is then derived from measurements taken on the patient directly or indirectly, for example, deduced from data measured prior to the first instant and then updated for the first instant.

[0171] Preferably, it consists of: - a scan of the arcade containing the attachments, at the first moment; or - a model resulting from an update of an "anterior" arch model carrying the attachments, or "anterior composite model", and generated at a time prior to the first time.

[0172] In one embodiment, the patient undergoes a scan of their dental arch onto which brackets have been previously fixed. The scan provides a first composite model representing both teeth and brackets, and thus, in particular, representing the brackets in their initial arrangement. The bracket models are included in the composite model.

[0173] The first composite model can represent a partially real situation, in particular when it includes - attachment models that represent attachments that are not actually fixed to the patient's teeth, and - an arch model representing the patient's arch, preferably cut into tooth models representing the teeth in their original arrangement.

[0174] Preferably, the arcade design consists of: - a model resulting from a scan of the arcade, at the first instant, or; - a model resulting from an update of a previous arch model of the arch, generated at an earlier time, or; - an assembly of historical or "type" tooth models, preferably chosen to resemble the actual teeth they represent, the assembly preferably being arranged so that the arrangement of the tooth models is identical to the arrangement of corresponding teeth represented on photos taken, preferably by the patient with their phone, at the first moment.

[0175] Such a first composite model allows testing of an attachment arrangement before its implementation in reality. It is thus possible to test different attachment arrangements in order to optimize the arrangement of the attachments to be subsequently implemented on the patient's teeth.

[0176] Preferably, at least one transfer plate, or "JIG," is manufactured, prepared, and / or ordered, on which the fasteners are arranged according to the computer-determined fastener arrangement. Transferring the fasteners using this plate thus ensures that the actual fastener arrangement conforms to the computer-determined fastener arrangement.

[0177] We now describe an update of an anterior arch model, but the update of an anterior composite model can be carried out in the same way.

[0178] The update preferably consists of modifying the position and orientation of the teeth of said anterior arch model so that they correspond to a scan or photographs of the arch at the first instant, in particular photographs, possibly extracted from a film, taken by the patient with his phone or with a laptop.

[0179] Preferably, the patient receives a notification indicating when to acquire said photos.

[0180] The anterior arch model is a digital model representing the teeth of the arch, in their arrangement on the dental arch at a time prior to the first time.

[0181] The anterior arch model is preferably prepared from measurements taken on the patient's teeth or on a physical model of his teeth, for example a plaster model or a 3D model digitized using a three-dimensional scanner.

[0182] The anterior arch model is preferably made less than one month before the start of orthodontic treatment, preferably less than two weeks, preferably less than one week before the start of orthodontic treatment, in particular immediately before or after the attachment of brackets, in order to accurately represent the arrangement of the teeth at the start of orthodontic treatment.

[0183] The anterior arch model may be a model generated at the beginning of orthodontic treatment.

[0184] To distort an anterior arch model, the model is cut to generate a digital model for each tooth, or "tooth model". Then the tooth models are moved to match their configurations in the photographs.

[0185] In other words, we are looking for an arrangement of tooth models that allows us to obtain views of the arch model that represent the teeth as in the photos.

[0186] The use of a scan or, preferably, photos taken by the patient with his phone avoids having him travel to the orthodontist's office if no change in the position and / or orientation of a bracket is necessary.

[0187] A method for updating or "updating" a model from photos is described for example in patent application EPI8184486.

[0188] Preferably, in step iii), the following steps are carried out: - we generate a composite anterior model of said arch at an anterior instant prior to the first instant, preferably at the beginning or before orthodontic treatment, preferably by a scan; - the previous composite model is cut by computer so as to generate, at least for each tooth with an attachment, a digital model of the tooth and the attachment it has, or "composite tooth model"; - At the first moment, the patient takes at least one photograph of the dental arch, preferably with their mobile phone, and transmits this photograph to a computer with access to the cut anterior composite model; then, the arrangement of the composite tooth models on the cut anterior composite model is modified to position said tooth models as shown in the photograph, so as to obtain the first composite model. This modification is preferably performed autonomously by the computer.

[0189] In step 2), steps a) and b) are implemented by computer.

[0190] In step a), the first attachment representation is received, preferably the first composite model.

[0191] In step b), the second attachment representation is determined by moving the attachment models from the first arrangement, or, equivalently, from the first composite model, by moving the tooth models.

[0192] This equivalence results from the fact that the attachment models represent the attachments immobilized on their respective fixing teeth. Like real attachments, each attachment model retains its position and orientation relative to the fixing tooth on which it is mounted.

[0193] According to option bl), the displacement of the attachment models results from a simulation of an orthodontic event, and in particular from the simulation of the effect of the wearing of one or more "second" arches by the patient after the first instant.

[0194] In a preferred embodiment, only the effect of the full-size bow is simulated, from the first arrangement of the attachments.

[0195] When the teeth are modeled, the option bl) is a b32 option).

[0196] According to option b2), the movement of the attachment models is carried out in such a way as to Arrange the attachment models in a target attachment model arrangement. This The arrangement is preferably predetermined, that is, known to the computer before the first instant. When the teeth are modeled, option b2) is an option b32).

[0197] For example, the attachment models are - positioned so that their centers of gravity follow the general curve of a dental arch, preferably the dental arch of the patient wearing the brackets, preferably in a plane, and - oriented so that their grooves follow said curve.

[0198] According to option b31), the movement of the attachment models is carried out so as to arrange the tooth models in a target tooth model arrangement. This arrangement is preferably predetermined, i.e., known by the computer before the first instant.

[0199] For example, the tooth models are arranged as in a model of a dental arch, preferably of the patient's dental arch which bears the brackets, representing the teeth in the desired arrangement at the end of orthodontic treatment, or at the end of an intermediate stage of orthodontic treatment.

[0200] In step 3), the computer verifies the conformity of the second arrangement of the attachment models, that is, their arrangement in the second representation of the attachments, or provides the practitioner with a visualization enabling them to perform this verification. For this purpose, preferably, the practitioner can view a second composite model on the computer screen and manipulate it with the computer.

[0201] After an option bl) or b2) or b32), it can evaluate whether the second arrangement of the attachment models is in accordance with the orthodontic treatment plan.

[0202] If the second archwire is the full-size archwire, it can specifically verify that the arrangement of the tooth models is physiologically possible and meets the objective of the orthodontic treatment plan. In this case, the second arrangement of the attachment models can be considered compliant.

[0203] If the second archwire is not the full-size archwire, it can, in particular, verify that the arrangement of the tooth models is physiologically possible and allows for the attachment of a test archwire intended to be attached to the brackets, and in particular the following archwire, that is, the archwire which, according to the orthodontic treatment plan, is to be worn after the second archwire, in a manner that meets the objective of the orthodontic treatment plan. In this case, the second arrangement of the bracket models can be considered compliant.

[0204] In one embodiment, the conformity check is carried out by a computer, with the practitioner or autonomously.

[0205] Preferably, after an option bl), the computer determines the compatibility of the second attachment arrangement with an arc, in particular the second arc or an arc to be tested. Preferably, the compatibility is binary, or "Boolean", i.e.- The word "dire" can only take two values ​​corresponding to compatibility and incompatibility.

[0206] Alternatively, compatibility is expressed as a compatibility score, for example, as a compatibility percentage. In this alternative mode, if this score exceeds a certain threshold, it is considered acceptable and the second attachment arrangement is considered compatible with said bow.

[0207] In a preferred embodiment, compatibility expresses the ability of the second arch, preferably the full-size arch, to exert appropriate orthodontic action if it were fixed to the teeth in the first attachment arrangement.

[0208] The capacity of the second arch can in particular be considered insufficient if the numerical simulation of the effect of the second arch leads to an arrangement of attachment models and, equivalently, tooth models, which does not respect the objective of the orthodontic treatment plan after use of the second arch.

[0209] It is also possible to verify, preferably by numerical simulation, whether the second arc could be attached to the fasteners in the first arrangement without being damaged or, more generally, without losing its effectiveness.

[0210] The capacity of the second arc can in particular be considered insufficient if the second arc - would break or deform plastically during its theoretical initial positioning, that is, the position in which it would be fixed to the fasteners arranged as in the initial arrangement of the fasteners; and / or - would exert an inappropriate action on the teeth after this positioning, and in particular, would exert too high or misdirected mechanical stress, in particular a stress which would lead to failure of an attachment (for example by detachment, opening of the clip, rupture of the elastomeric ligature, etc.) or to a physiological stress affecting the integrity of one or more teeth (for example ligament, root resorption, recession of soft tissues, or even defenestration relative to the bone envelope).

[0211] Similarly, the capacity of a test bow may in particular be considered insufficient if the test bow - would break or deform plastically during its theoretical positioning at the second instant, that is, in which it would be fixed to the fasteners arranged as in the second arrangement of the fasteners; and / or - would exert an inappropriate action on the teeth after this positioning, and in particular, would exert excessive or misdirected mechanical stress, especially stress that would lead to bracket failure (e.g., detachment, clip opening, elastomeric ligature breakage, etc.) or physiological stress affecting the integrity of one or more teeth (e.g. ligament, root resorption, soft tissue recession, or even defenestration relative to the bony envelope).

[0212] Following an option bl), steps A) and B) for verifying such a capability of a test bow, with regard to the second attachment arrangement, are described below. Those skilled in the art understand that they would also apply, by analogy, to verifying the same capability for a second bow, with regard to the first attachment arrangement.

[0213] In step A), a maximum stress is determined by computer from the second representation of attachments, preferably from the second composite model, and from information on the mechanical properties of the arc to be tested.

[0214] In a preferred embodiment, the maximum stress is the greatest value of a mechanical stress along the arc to be tested experienced by the arc to be tested when the arc to be tested is attached to said fasteners in the service position.

[0215] In another embodiment, the maximum stress is the largest value of the local stress along the arc to be tested considering not only the service position, but also all shapes from its resting form to its form in the service position.

[0216] The parameters for determining how an arc deforms are known. These include, in particular, the type of arc, the material from which the arc is made, the Young's modulus of the arc being tested, the shape and dimensions of the arc at rest, especially an equivalent diameter in cross-section. For shape-memory arcs, the parameters may also include thermoelastic phases.

[0217] The shape of the arch to be tested in the service position can be determined, at least approximately, from the second attachment arrangement provided by the second attachment representation, preferably the second composite model. In one embodiment, the anchoring zones of the arch to be tested on the attachments are determined by analyzing the second attachment representation, preferably the second composite model. A computer can, in particular, recognize the anchoring zones of the attachments on the arch to be tested because they have specific shapes, especially a groove shape.

[0218] A neural network can also be trained for this purpose.

[0219] The anchoring zones can also be easily identified by an operator. The operator can, for example, mark on the first and / or second representations of attachments, preferably on the first or second composite model, displayed on a screen, the surfaces corresponding to the anchoring zones.

[0220] In a preferred embodiment, only the anchoring zone of the fastener is represented in the first and / or second representation of fasteners, in such a way Faithful or hyperrealistic, or symbolic. Preferably, the throat is represented by a straight line segment.

[0221] In one embodiment, each anchoring zone is simplified into two points or zones of predefined shape, "input" and "output", marking the "input" and "output" ends of the arc to be tested in the receiving groove defined by the attachment.

[0222] To define the maximum stress, the model of the arc to be tested is deformed so that the longitudinal axis of this model passes through all of said points or said zones for the fasteners used for fixing the arc to be tested.

[0223] The simpler the modeling of the anchoring zone and / or the arc to be tested, the faster the determination of the shape of the arc to be tested and the fewer resources are required for this determination. In one embodiment, the arc to be tested is modeled as a curve following the general shape of the arc, and this curve is deformed until it passes through each attachment, preferably through each of the two entry and exit points of each attachment.

[0224] The anchorage area of ​​a fastener, in particular an area of ​​predefined shape, can be determined according to the type of fastener (for example, ligating, self-ligating...) and / or the morphology and / or the dimensioning of the attachment groove and / or the manufacturer, and / or one or more dimensions of the fastener and / or one or more of the materials constituting the fastener.

[0225] In a preferred embodiment, the fasteners are considered to be rigid when determining the shape of the bow to be tested in the service position. In another embodiment, the deformation of the fasteners resulting from the interaction between the bow to be tested and the fasteners is taken into account.

[0226] In one embodiment, a neural network can be trained to directly determine the shape of the arc to be tested as a function of the second composite model.

[0227] In one embodiment, the maximum stress is determined by calculation, according to any known technique, for example from a model of the arc to be tested, by finite element calculation.

[0228] In particular, - the properties of the constituent material(s) of the arc to be tested; and - the resting shape of the arc to be tested; are known.

[0229] It is therefore possible to enhance a model of the arc to be tested so that it is realistically deformable, that is, so that it deforms like the arc to be tested when forces are applied to it virtually. It is also possible to enhance the model of the arc to be tested so that it provides local values ​​for said constraint, throughout the arc, depending on the shape imposed on it, for example by finite element calculation.

[0230] The model of the arc to be tested thus enriched, or "dynamic model", thus includes not only a numerical model of this arc at rest, but also defines its deformation capacities and the resulting field of stresses.

[0231] When the service position of the arc to be tested has been simulated, i.e. the shape of this arc has been determined in this position and the model of the arc to be tested has been deformed accordingly, the enriched arc model can provide values ​​for the local mechanical stress at any point along the arc, which makes it possible to determine the maximum stress.

[0232] The maximum stress can be determined by other techniques, for example from measurements of the stress field carried out on the arc to be tested in different shapes. These measurements can, in particular, be stored in computer memory. It is then simply a matter of searching for those that correspond to the anticipated shape of the arc to be tested in the service position.

[0233] Advantageously, the local stresses along the entire arc to be tested can be displayed as a “color map”. This type of display allows the practitioner to clearly and efficiently identify the portion or portions of the arc to be tested where the stress is maximal.

[0234] The maximum constraint in the service position can also be defined statistically, in particular by implementing one or more neural networks.

[0235] In step B), the computer determines the compatibility of the arch to be tested with the second attachment arrangement in the second composite model. The compatibility depends on the difference between the maximum stress determined in the previous step and a threshold stress, preferably predetermined. For example, the threshold stress may define a limit beyond which the arch to be tested deforms plastically. The compatibility is preferably binary, depending on whether the difference is positive or negative.

[0236] The computer is preferably a computer that has implemented step A).

[0237] Preferably, the computer generates information, preferably in written or audio form, expressing compatibility. This information may be presented, in particular, to a practitioner and / or installer, and / or patient, and / or arch manufacturer. The form of the presentation may be adapted accordingly.

[0238] Preferably, the information is transmitted to the patient's telephone so that the patient can display it, for example in the form of a message.

[0239] In step 4), in case of incompatibility, the practitioner may in particular - modify the configuration of one or more of the attachment models in the first composite model, for example by modifying the height and / or orientation of one or more of the attachment models, and / or - when the brackets have already been fixed to the patient's teeth, modify the arrangement of the brackets on the arch.

[0240] In one embodiment, the modification of the first arrangement of the attachment models is carried out by a computer, autonomously. Computer program

[0241] The computer program can be executed to implement a process described above.

[0242] In step a), the first representation of attachments can be obtained as described in step 1).

[0243] In step b), the second attachment representation can be obtained as described in step 2).

[0244] In step c), the conformity verification c can be obtained as described in step 3).

[0245] In step d), the modification of the position and / or orientation of at least one attachment model in the first composite model can be carried out as described in step 4). Examples

[0246] At step a), the first attachment representation is received or generated as described above.

[0247] In step b), the attachment models are identified, and optionally the tooth models if the first arrangement is a composite model, at least for the attachment teeth (step b32)). This identification can be performed by segmenting the attachments and optionally the teeth, on the first attachment representation. Preferably, the attachment slots are segmented. Several well-known techniques can be used for this segmentation step. Examples include segmentation by curvature (Ricci tensor), segmentation by Principal Component Analysis (PCA) on data or combinations of data, or segmentation by machine learning using a PointNet++ architecture, although this list is not exhaustive. Step bl) or b32)

[0248] In order to obtain the second arrangement of the attachment models, the attachment models of the first attachment representation, preferably the groove models of said attachment models (and the fastening tooth models if the first (representation of attachments is composite) are moved to be aligned according to the resting shape of a second arc.

[0249] This step can be performed using any software that allows for the movement of objects (models, for example). Well-known 3D design software such as CATIA® or AUTOCAD® can be used, for instance. This list is not exhaustive. Step b2) or b32)

[0250] In order to obtain the second arrangement of attachment models, the attachment models of the first attachment representation, preferably the groove models of said attachment models, (and the attachment tooth models if the first attachment representation is composite) are moved to be aligned according to a target attachment model arrangement, generally determined during the design of the treatment plan.

[0251] This step can be performed, for example, using non-rigid transformations, such as PASHA (Partially Scalable and Hierarchical Alignment) or RUNA (Rigid Unified Nonlinear Alignment) algorithms, or using rigid transformations, such as an ICP (Iterative Closest Point) algorithm. This list is not exhaustive. These algorithms allow us to quantify the displacements required to move from the first arrangement of attachment models to the second arrangement of attachment models. Step b31)

[0252] In order to obtain the second arrangement of attachment models, the composite models of the first attachment representation are moved to be aligned according to an arrangement of target tooth models, generally determined during the design of the treatment plan. This step can be performed, for example, using non-rigid transformations, such as PASHA (Partially Scalable and Hierarchical Alignment) or RUNA (Rigid Unified Nonlinear Alignment) algorithms, or using rigid transformations, such as an ICP (Iterative Closest Point) algorithm (this list is not exhaustive). These algorithms allow us to quantify the displacements required to move from the first arrangement of attachment models to the second arrangement of attachment models.

[0253] In step c2), the second attachment pattern arrangement is compared to a target attachment pattern arrangement and / or a target tooth pattern arrangement, by quantifying the distance between this second attachment pattern arrangement and the target arrangement. Based on this distance, the second attachment pattern arrangement is either in accordance with the treatment plan or not.

[0254] There are several methods known to those skilled in the art for estimating this distance: distance map, surface tolerance, point-to-point distance. This list is not exhaustive.

[0255] It can also be verified that the absolute and / or relative positions and / or orientations of the attachment models and / or tooth models are within predefined ranges of positions and orientations.

[0256] In one embodiment, the compatibility of the first arrangement of the fasteners with the arc to be tested is checked by finite element calculation. Example: checking the fastening of the fasteners

[0257] In a particularly advantageous embodiment, the program according to the first main aspect is used to detect an early error in the positioning of the fasteners.

[0258] In particular, the fasteners are sometimes fixed by unqualified persons and it is useful to check that this fixing is correct.

[0259] The check of the attachment fixation can be carried out, at a first moment, whether or not the patient is wearing an arc.

[0260] The first representation of attachments can be a first composite model.

[0261] In a first, preferred variant, the computer simulates the effect of a second archwire, and in particular the full-size archwire, on the first bracket representation, preferably a composite model, so as to generate the second bracket representation, and then presents the second bracket representation to the practitioner so that they can determine whether it conforms to the objective of the orthodontic treatment. Alternatively, and preferably, the computer evaluates this conformity itself.

[0262] Remarkably, the simulation can be performed even when the brackets are not arranged as they will be at the moment the second archwire is attached. For example, the first moment could be at the beginning of treatment, and the second archwire could be the full-size archwire, intended to be attached after several intermediate archwires have been used since the first moment. It is not necessary to simulate the effects of these successive intermediate archwires. The effect of the full-size archwire on the teeth as arranged at the first moment can be simulated, even though, in reality, due to the use of intermediate archwires, the teeth will no longer be arranged in this way at the moment the full-size archwire is actually attached to the brackets.

[0263] In a second embodiment, the second attachment representation is preferably the result of a step b2) in which the computer moves the attachment models so as to arrange them according to a second arrangement of the attachment models, namely an arrangement of the target attachment models, preferably such that said models attachments should be in a common plane, preferably horizontal, and / or aligned along a curve following the general shape of the arch of the fixing teeth.

[0264] Preferably, the computer moves composite tooth models, that is to say models consisting each of a tooth model representing a respective tooth and, for fixation teeth, of an attachment model representing an attachment that is fixed to it.

[0265] The arrangement of the attachment models according to the arrangement of the target attachment models corresponds to a second arrangement of the composite tooth models.

[0266] The computer can present the second arrangement of the composite tooth models to a practitioner so that the practitioner can verify whether this arrangement is acceptable with regard to the orthodontic treatment plan. In particular, the computer can present the second arrangement of the composite tooth models so that the practitioner can verify whether the last archwire provided for in the orthodontic treatment plan, if it were fixed to the teeth if they were arranged so that the brackets are arranged as in the second arrangement of the bracket models, would be able to move the teeth to achieve the objective of the orthodontic treatment.

[0267] For the first and second variants, the computer can itself perform a conformity check, in particular by comparing the positions of the composite tooth models with each other, for example to check whether - the centroids of the composite tooth models are aligned according to the general shape of the arch which supports the fixation teeth, preferably with a margin of tolerance; and / or - the distal ends, i.e., the apices, of the composite tooth models are aligned in a plane, preferably with a margin of tolerance; and / or - the distances between adjacent composite tooth models are zero, preferably with a margin of tolerance; and / or - the alignment of the teeth respects an aesthetic criterion such as the smile line.

[0268] The computer may alternatively, or in addition, verify whether the composite tooth models are arranged as in a model of the arch as desired at the end of orthodontic treatment, or "objective model", for example to verify whether - the distances between the barycenters of the composite tooth models and the barycenters of the corresponding tooth models in the objective model are zero, preferably with a margin of tolerance; and / or - the differences in orientation between the composite tooth models and the corresponding tooth models of the objective model are zero, preferably with a margin of tolerance.

[0269] In a third variant, the attachment models are included in composite tooth models and the second attachment representation is the result of a step b3) in which the computer moves the composite tooth models so as to arrange them in a target tooth model arrangement.

[0270] The arrangement of the target tooth models may be a generic arrangement, applicable to several patients, for example be such that the distal edges of the teeth extend in a plane, preferably horizontal, or are aligned along a curve following a generic dental arch representing a typical arch and preferably resulting from the statistical processing of data from a plurality of patients.

[0271] The arrangement of the target tooth models may be an arrangement specific to the orthodontic treatment, for example an arrangement corresponding to the desired arrangement for the teeth at the end of treatment.

[0272] As a consequence of the displacement of the composite tooth models, the attachment models are then arranged according to a second arrangement of attachment models.

[0273] The computer can present the second arrangement of the composite tooth models to a practitioner so that the practitioner can verify whether this arrangement is acceptable with regard to the orthodontic treatment plan. In particular, the computer can present the second arrangement of the composite tooth models so that the practitioner can verify whether the last archwire planned in the orthodontic treatment plan could be attached to the brackets if they were arranged according to the second arrangement of the bracket models and, if so, whether this archwire would be capable of moving the teeth to achieve the objective of the orthodontic treatment.

[0274] Alternatively, or in addition, the computer can itself perform a conformity check, in particular by comparing the positions of the attachment models with each other, for example to check if - the centers of gravity of the attachment models are aligned according to the general shape of the arch that supports the fixing teeth, preferably with a margin of tolerance; and / or - the positions and orientations of the attachment models are adapted to receive the last arch planned according to the orthodontic treatment plan, for example by comparing the possible shapes for this arch with the second arrangement of the attachment models to check if there is a shape allowing the attachment of the arch.

[0275] In the event of detection of a non-conformity, the attachment(s) incorrectly glued to the teeth can be detached and then repositioned in the correct place.

[0276] Second main aspect: checking a test bow before its manufacture and / or attachment to the fasteners

[0277] In step 1'), a first representation of attachments is generated, which represents the attachments fixed to the patient's teeth. The first representation of attachments can be an image, preferably a photo acquired by the patient with their mobile phone, or a first composite model. It can be generated as described for steps a) or 1) described above.

[0278] A first composite model is preferably obtained by updating a previous composite model from a scan or photos, possibly extracted from a film, acquired by the patient, preferably with his mobile phone, as in embodiment iii) described above.

[0279] The first moment can be chosen by the practitioner. It corresponds to a moment when the practitioner considers that the patient should move to the next arch in the sequence of arches in the orthodontic treatment plan and when he wishes to verify the suitability of this arch to the current arrangement of the brackets.

[0280] The first moment is a current moment, during orthodontic treatment. The first moment is not necessarily during the stage of orthodontic treatment that is chronologically the first. For the second main aspect, the adjectives "first" and "current" therefore have the same meaning.

[0281] The first moment is preferably included in a step subsequent to the step which initiates the orthodontic treatment, preferably more than one week, more than two weeks, more than three weeks, more than one month, more than two months, more than three months after the start of the orthodontic treatment.

[0282] A notification can be sent to the patient to indicate the opportune time to perform a scan or acquire photos.

[0283] At the first instant, the patient wears a first “actual” bow.

[0284] The orthodontic treatment plan defines a sequence of archwires to be successively attached to the brackets. The archwire to be tested may be a future archwire intended to be attached to said brackets after the first archwire, according to the orthodontic treatment plan.

[0285] It is then necessary to assess whether the future arch, preferably the arch that the patient should wear immediately after the first arch, is suitable for the first arrangement of the attachments.

[0286] In step 2'), a computer evaluates, from the first representation of attachments, a compatibility of the first arrangement of attachments with the arc to be tested. Compatibility can be determined as described in step c), preferably following steps A) and B) described above, but starting from the first representation of attachments:

[0287] In step A), a maximum stress is determined by computer from the first representation of attachments, preferably from the first composite model, and from information on the mechanical properties of the arc to be tested.

[0288] At step B), the computer determines the compatibility of the arc to be tested with the first arrangement of the attachments.

[0289] Compatibility may be the result of a deformation calculation, in particular an evaluation of the mechanical stresses experienced by the arc to be tested when mounted on the attachments, preferably represented by one or more points on the first representation of attachments, in the form of an image or a model.

[0290] Compatibility therefore defines the ability of the arch to be tested to be put into service position in the current arrangement of brackets and to implement the next step of the orthodontic treatment plan.

[0291] At step 3'), the computer generates information, preferably written or audible, expressing compatibility.

[0292] The information may, for example, include: - binary information such as "Proceed to the next arc" or "Do not proceed to the next arc"; and / or - a 2D or 3D representation of the insertion and / or deformation of the bow in the attachments, optionally highlighting "collisions" and / or mechanical stress; - a representation, preferably simplified, of the teeth which do not allow the insertion of the arch to be tested, for example in the form of a dental diagram in which these teeth are highlighted, for example represented in red.

[0293] The information may be presented in particular to a practitioner and / or installer, and / or patient and / or bow manufacturer. The form of the presentation may be adapted accordingly.

[0294] Preferably, the information is transmitted to the patient's telephone so that the patient can display it, for example in the form of a message.

[0295] In step 4'), which follows step 3'), compatibility is used to organize the continuation of orthodontic treatment.

[0296] If the compatibility is satisfactory, typically because the maximum stress is less than or equal to the threshold stress, the attachment of the arc to be tested to the attachments is possible under good conditions.

[0297] An appointment to replace the current archwire, fixed to the patient's teeth, with the test archwire and / or the manufacture of the test archwire can be scheduled, preferably by computer.

[0298] The patient's appointment is preferably less than two weeks after the first at the moment, the fasteners are still advantageously arranged substantially in the first arrangement of the fasteners, that is to say in the current arrangement.

[0299] In particular, the first composite model is preferably generated from a scan or, preferably, from photographs, possibly extracted from a film, taken and transmitted by the patient at the first moment and, if the compatibility is satisfactory, - the patient receives a message in return indicating that they must make an appointment with an installer, or even offering them appointment dates, in order to replace the archwire they are wearing; and / or

[0300] - the practitioner and / or installer receive information to notify the patient that an appointment at the office is necessary; and / or - The manufacturer of the test arc receives a message indicating that they must manufacture the test arc and / or send it to an installer, and in particular to the patient or practitioner; and / or - the practitioner may receive a message in return indicating that they must offer the patient an appointment and / or prepare the bow, or even suggest appointment dates;

[0301] and / or

[0302] - the practitioner sends the bow directly to the patient.

[0303] If it is not available, the test archwire is then manufactured, ordered, and sent to the installer. If the installer is not the patient, an appointment is made between the patient and the installer. The test archwire is then attached to the brackets as a replacement or supplement to the first archwire, after optionally modifying the test archwire and / or the shape of one or more brackets and / or the position and / or orientation of one or more brackets.

[0304] If the compatibility is unsatisfactory, typically because the maximum constraint exceeds the threshold constraint, - no planning is done; and / or - the patient receives a message in return indicating that they must make an appointment with the practitioner, or even suggesting appointment dates, for a check and / or modification of the orthodontic appliance they are wearing; and / or - the practitioner receives a message in return indicating that he must offer an appointment to the patient.

[0305] The modification of the orthodontic appliance preferably involves a modification of the first arch, for example of the resting shape of the first arch, and / or the position of the first arch and / or the shape and / or the position and / or the orientation of one or more brackets.

[0306] The modification of the orthodontic appliance may also include the attachment of one or more additional brackets and / or an auxiliary device, for example a chain.

[0307] An example is now described.

[0308] At step 1'), the first attachment representation is received or generated as described above.

[0309] In step 2'), the attachment models are identified and optionally the tooth models if the first arrangement is a composite model, at least for the teeth of attachment. This identification can be performed by segmenting the attachments and optionally the teeth, on the first attachment representation. Preferably, the attachment grooves are segmented. Several well-known techniques can be used for this segmentation step. Examples include segmentation by curvature (Ricci tensor), segmentation by Principal Component Analysis (PCA) on data or combinations of data, and segmentation by Machine Learning using a PointNet++ architecture; this list is not exhaustive.

[0310] Preferably, models representing the grooves of the fasteners are created. This step can be carried out, for example, by optimization or by machine learning using networks of the type TCN (Temporal Convolutional Networks) or GCN (Graph Convolutional Networks). This list is not exhaustive.

[0311] Preferably, to speed up the process, the arc to be tested can be approximated into a series of segments, for example by skeletonization.

[0312] The compatibility of the initial attachment arrangement with the arc to be tested is then determined by finite element analysis. For example, well-known 3D design software such as CATIA® or AUTOCAD® may be used. This list is not exhaustive.

[0313] As is now clearly apparent, the process according to the second main aspect makes it possible to optimize orthodontic treatment, and in particular to avoid scheduling unnecessary appointments, or even to manufacture unsuitable arches.

[0314] Of course, the invention is not limited to the embodiments described in detail above.

[0315] Not all attachments are necessarily used at each stage. In particular, the practitioner may decide, from the first arrangement, to engage only some of the attachments in the arch.

Claims

Demands

1. System for implementing a method for testing an orthodontic appliance worn by a patient during orthodontic treatment, the orthodontic appliance comprising a set of brackets fixed to a patient's dental arch, in a first arrangement of brackets, and a first archwire attached to said brackets, the method comprising the following steps: 1') receiving or generating a first representation of brackets representing said brackets in the first arrangement of brackets; 2') evaluating, by computer, from the first representation of brackets, the compatibility of the first arrangement of brackets with an archwire to be tested intended to be attached to said brackets;3') depending on the compatibility, presentation, by the computer, of an information message, preferably at least to the patient and / or the practitioner implementing the orthodontic treatment, the message preferably giving indications on the compatibility and / or on a step of the orthodontic treatment which depends on the compatibility; said system comprising: - a device for acquiring a scan, photos and / or a film, for step 1'), and - a computer programmed to implement step 1'), and / or step 2'), and / or step 3').;

2. A system according to the immediately preceding claim, wherein said arch to be tested is a future arch intended to be attached to said brackets after the first arch, according to the chronology defined by the orthodontic treatment plan.

3. System according to any one of the preceding claims, comprising, after step 3'), a subsequent step 4'): 4') only if compatible, scheduling an appointment with the patient and / or checking and / or modifying the orthodontic appliance worn by the patient.

4. A system according to the immediately preceding claim, wherein said modification comprises - a replacement of the first arc by the arc to be tested, after having optionally modified the arc to be tested, optionally without attaching the arch to be tested at all attachments, or a modification of the first arch and / or the position of the first arch and / or of one or more attachments and / or of the position and / or orientation of one or more attachments; and / or - the fixing of one or more additional attachments and / or of an auxiliary device, and / or an intervention on the patient's teeth, and / or on an auxiliary device, worn by the patient.

5. System according to any one of the preceding claims, wherein the first representation of attachments is one or more images, preferably at least one photo acquired by the patient, preferably with his phone, or is a three-dimensional model, preferably obtained by deformation, by means of a computer, of a prior model.

6. A system according to any one of the preceding claims, wherein the information message indicates whether the orthodontic appliance worn by the patient should be maintained, and / or checked and / or modified.

7. A system according to any one of the preceding claims, wherein a computer, in step 2'), A) determines, from the first representation of brackets and information on the mechanical properties of the arch to be tested, a maximum stress equal to - the greatest value of a mechanical stress along the arch to be tested experienced when the arch to be tested is attached to said brackets in the first arrangement of brackets, or - the greatest value of a mechanical stress along the arch to be tested experienced when the arch is deformed from a resting configuration to a service configuration in which the orthodontic arch to be tested is fixed to the brackets in the first arrangement of brackets; B) determines, from the difference between said maximum stress and a threshold stress, said compatibility; then, in step 3'), generates information expressing the compatibility.

8. A system according to any one of the preceding claims, wherein compatibility is expressed in the form of a compatibility score and in which optionally, for compatibility to be verified, a threshold score must be exceeded. 44

9. A computer program comprising code instructions which, when executed by a computer, perform a process comprising steps 1') to 3') according to any one of the preceding claims, and preferably step 4') according to any one of claims 3 to 8.

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