Method for acquiring model of dental arch

Abstract

The invention relates to a method for acquiring at least one image of at least one dental arch of a user (U) by means of a mobile phone (12 ') and an acquisition tool (31') comprising an acquisition head (32 ') provided with a camera (33'), in which method the acquisition head: acquires an image and sends the image to the mobile phone, or-acquiring a signal and transmitting the signal to the mobile phone in order for the mobile phone to generate an image from the signal autonomously or by means of a computer communicating with said mobile phone, the method comprising an analysis of the image after the acquisition step, in order to define the dental condition of the user and / or to check the correct implementation of an ongoing active or passive orthodontic treatment.

Description

Technical Field

[0001] The invention relates to a method for acquiring a model of a user's dental arch and a computer program for implementing the method. Background Art

[0002] It is desirable for each person to have their teeth checked regularly, particularly to ensure that the position and / or shape and / or appearance (or "texture") of their teeth has not changed adversely.

[0003] In the case of orthodontic treatment, this unfavorable trend may lead to a change in treatment. After orthodontic treatment, this unfavorable trend, known as "relapse", may lead to the need for retreatment. Finally, in a more general manner and independent of any treatment, each person may wish to monitor any movement and / or changes in the shape and / or appearance of their teeth.

[0004] Traditionally, the examinations are performed by orthodontists or dentists, who are the only ones with the right equipment. These examinations are therefore expensive. Furthermore, the visits are cumbersome. Finally, the available professional scanners are accurate but require special skills. These professional scanners are usually used on the patient for intraoral acquisitions or on a dental cast of the patient's dental arch for extraoral acquisitions.

[0005] In addition, US15 / 522,520 describes a method that enables accurate assessment of the movement and / or deformation of the teeth since an initial moment, based on a simple photograph of the teeth taken by the user at an updated moment. To this end, a digital three-dimensional model of the user's dental arch is preferably created using a professional scanner. This initial model is then cut to define a tooth model for each tooth. Finally, the tooth models are moved to transform the initial dental arch model to match the photograph as closely as possible. The method produces a model of the current dental arch with excellent accuracy without the user having to go to the dentist to scan their teeth. This model can then be compared with the initial model to check the positioning and / or shape of the user's teeth.

[0006] This method is convenient for the user, but requires at least one appointment to acquire an initial dental arch model. Heavy computer processing is then required to decompose and then deform the initial model.

[0007] Therefore, there is a need for a method of remotely monitoring a user's dental condition as described in US 15 / 522,520, but which is even more convenient for the user and quicker to implement.

[0008] It is an object of the present invention to at least partially solve this problem. Summary of the invention

[0009] The present invention provides a method for acquiring a model of at least one dental arch of a user, the method comprising the following steps:

[0010] a) at the moment of updating, a digital three-dimensional model or "captured model" of the dental arch is acquired by the user, preferably extraorally, using a portable scanner, and optionally trimming the dental arch model in order to separate a part of the dental arch model (preferably a tooth model),

[0011] In order to obtain an “updated model”, the updated model is the acquired model or a part of the acquired model separated by cutting, and the object represented by the updated model is called an “updated object”.

[0012] As will be seen in more detail later in the specification, the inventors have discovered that a portable scanner can be used to produce a model of a dental arch or teeth of sufficient quality for orthodontic use (preferably extraorally and without special precautions). This approach appears to be incompatible with the acquisition of a sufficiently complete and accurate model.

[0013] Advantageously, the acquisition can be performed by the user himself, which opens up a wide range of applications. In particular, the acquisition no longer requires a visit to a dental professional. Furthermore, the method according to the invention enables a faster analysis of the user's dental condition than with prior art methods. In particular, there is no need to construct a dental arch model from a photograph.

[0014] Generally speaking, a 3D model of a dental arch is traditionally acquired intraorally using an optical 3D scanner. Intraoral acquisition enables the sensor to be very close to the dental arch and thus provides highly accurate information.

[0015] Extra-oral (or "extra-oral") acquisition devices (i.e., acquisition sensors (especially those of cameras or still cameras) that are not inserted into the user's mouth) are a recent development and use photographs to deform an initial model obtained with a conventional optical 3D scanner. The computer processing required for this deformation is expensive.

[0016] The inventors are to their credit that they have tested portable (preferably extraoral) scanners, in particular laser telemetry sensors, and have found that such scanners enable patients to acquire a high quality model of their dental arch. Advantageously, an initial model (e.g. acquired at the beginning of orthodontic treatment) does not need to be acquired and then deformed from the images acquired by the scanner. By processing the images acquired by the scanner, a model of the dental arch can be directly obtained following the techniques conventionally used for 3D optical scanners.

[0017] In an advantageous embodiment, the portable scanner is low precision. All that needs to be done is to record the spatial position of a few notable points on the dental arch to create an updated model. Advantageously, the low precision model can be acquired using limited portable technical means. The low precision model also requires little memory to store. The low precision model can be easily and quickly sent remotely, for example by radio.

[0018] Preferably, a portable scanner

[0019] - integrated into a mobile phone for so-called extra-oral acquisition, or

[0020] - comprising a mobile phone and a collection tool, the collection tool comprising a collection head that can be inserted into the user's mouth, the collection head

[0021] - preferably using a laser remote sensor to acquire the acquired model and sending the acquired model to a mobile phone, or

[0022] - Acquiring a signal and transmitting the signal to a mobile phone so that the mobile phone generates an acquired model from the signal autonomously or using a computer in communication with the mobile phone.

[0023] Preferably, the mobile phone sends the acquired and / or updated model to the dental professional, preferably over the air, preferably at a distance greater than 100 m or greater than 1 km or greater than 10 km and / or less than 50,000 km from the user.

[0024] The analysis method according to the present invention may further include one or more of the following optional features:

[0025] - in step a), the updated model is processed by a computer in order to correct the updated model, which correction potentially includes modifying the updated model or replacing the updated model with a corrected model;

[0026] - in step a), comparing the updated model with the calibration model in order to obtain a measure of the difference in shape between the updated model and the calibration model, and then

[0027] - modifying the updated model, preferably by means of a metaheuristic method (in particular selected from the methods listed below), preferably by simulated annealing, so as to reduce said shape difference, preferably so as to minimize said shape difference, or

[0028] - depending on the measurement, the updated model remains unchanged or the updated model is replaced by a corrected model;

[0029] - in step a), submitting the updated model to a neural network that is trained to render more realistically the digital three-dimensional model presented to it as input;

[0030] - the object of update is the dental arch of the user or the teeth of the dental arch;

[0031] -The calibration model is a model like this

[0032] - obtained by scanning the updated object at a time different from the time of the update, or

[0033] - represents said object updated with a theoretical shape, preferably generated by simulation, or

[0034] - a model representing a group of individual objects of the same type as the updated object, preferably dental arches or teeth, such as a standard dental model (typodont) or teeth generated from a standard dental model;

[0035] - The calibration model is:

[0036] - a model of the updated object obtained by scanning, preferably with a portable scanner or with a professional scanner, preferably more than 2 weeks, 4 weeks, 6 weeks, 2 months, 3 months and / or less than 12 months or less than 6 months before the moment of updating, or

[0037] - a model of the updated object, which simulates the shape of said updated object as expected for the moment of update, and which model is preferably implemented at a moment greater than 2 weeks, 4 weeks, 6 weeks, 2 months, 3 months and / or less than 6 months before the moment of update, or

[0038] - a model of the updated object, which simulates the shape of said updated object as expected for a "correction" moment after or before the moment of updating, the time interval between the moment of updating and the moment of correction being preferably greater than one week, more preferably greater than 2 weeks, 4 weeks, 6 weeks, 2 months and / or less than 6 months,

[0039] The model has preferably been generated more than 2 weeks, more than 4 weeks, more than 6 weeks, more than 2 months or more than 3 months before the time of updating, or

[0040] a historical model selected from a historical library comprising more than 1,000 historical models representing the same type of object as the updated model, the selection preferably being directed in such a way that the selected historical model is the historical model having the shape closest to the updated model, or

[0041] - a model obtained by statistically processing the historical models in the historical library, preferably in such a way that the model obtained by statistical processing represents a group of individuals; - the historical library only includes historical models that meet the same classification criteria as the updated model, e.g.

[0042] such as historical models associated with individuals who have at least one characteristic in common with the user (e.g. same age and / or same gender and / or same pathology and / or undergoing the same or similar orthodontic treatment);

[0043] - in step a), correcting the updated model by inputting the updated model to the input of a neural network trained to correct the model, the neural network preferably being selected from the neural networks listed in the detailed description of step iv) below; and / or

[0044] - In step a), the updated model is corrected in the following steps:

[0045] i) creating a history library comprising more than 1,000, preferably more than 5,000, more preferably more than 10,000 history models, each history model respectively modeling the same type of object as the updated object, e.g. if the updated model is modeling a dental arch or teeth, then the history model models the dental arch or teeth, and assigning a value for the classification criterion to each history model;

[0046] ii) analyzing the updated model to determine a value of the classification criterion for the updated object;

[0047] iii) searching the history base for a history model having the same value for said classification criterion and presenting the greatest closeness to said updated model or "best model";

[0048] iv) modifying the updated model based on the information about the best model, which may include replacing the updated model with the best model;

[0049] - in step a), the acquired model is decomposed so as to define a plurality of tooth models, then for each tooth model considered as an updated model, a loop of steps i) to iv) is performed, wherein the best model determined in step iv) is arranged so as to replace said tooth model in the acquired model, which advantageously makes it possible to reconstruct a high-precision dental arch model from the acquired low-precision model;

[0050] - In step a), the updated model is corrected in the following steps:

[0051] i')Definition:

[0052] a first determined region consisting of points or "first determined points" of the updated model representing a portion of the patient (e.g. a tooth) with an accuracy greater than 90%, preferably greater than 95%, more preferably greater than 99%, and

[0053] - a first uncertainty region, which constitutes the 100% complement of the updated model;

[0054] ii') extrapolating the first determined region only from the first determined region to define a first reconstruction region in the region of the first uncertain region, and then

[0055] definition:

[0056] a second zone of determination, consisting of points of the first zone of uncertainty or "second points of determination" which are separated from the first reconstructed zone by a distance less than a threshold distance; and

[0057] - a second uncertainty region which constitutes the 100% complement of the first uncertainty region;

[0058] iii') extrapolating from the single set a set consisting of the first uncertainty zone and the second uncertainty zone to define a second reconstruction zone in the region of the second uncertainty zone, and then

[0059] - replacing the second uncertainty region with the second reconstructed region in order to obtain a clean updated model;

[0060] - in step a), correcting the updated model by subjecting it to a neural network trained by providing it with as input an original model of an object of the same type as the updated object and outputting as output said original model rendered hyper-realistically;

[0061] - in step a), the updated model is processed by a computer to simplify the updated model;

[0062] - the portable scanner is integrated into a mobile phone or comprises a mobile phone and a collection tool comprising a collection head that can be inserted into the mouth of the user, the collection tool communicating with the mobile phone to send the collected model or updated model;

[0063] - The acquisition head is preferably via Bluetooth or cable to a mobile phone;

[0064] - a mobile phone for sending the acquired or updated model by radio, preferably to a dental professional, in particular to an orthodontist, and / or to a data processing center, preferably for implementing steps b) and / or c);

[0065] -The portable scanners are laser long-range sensors known as lidar, for "light detection and ranging";

[0066] - In step a), a portable scanner projects structured light directly onto the patient's teeth and acquires an image other than a photograph;

[0067] - in step a), the user modifies the tilt angle of the portable scanner, preferably by moving the portable scanner horizontally and / or vertically relative to the patient's teeth, preferably with open or closed mouth;

[0068] - in step a), the user expands their lips and / or cheeks to make their teeth visible to the portable scanner and then acquires the acquired model preferably extra-orally (i.e. without bringing the portable scanner even partially into their mouth);

[0069] - Preferably, the user uses a retractor and / or a portable scanner support to improve the quality of the acquired model;

[0070] - In step a), the portable scanner is fixed on a support having an edge which is inserted between the lips and teeth of the user;

[0071] - the support frame comprises a tubular spacer defining an oral opening, the rim extending to the periphery of the oral opening;

[0072] - in step a), the user modifies the tilt angle of the portable scanner by preferably moving the support frame horizontally and / or vertically relative to the patient's teeth, preferably in open and closed mouth, so as to keep the edge of the support frame between the user's teeth and the user's lips;

[0073] - in step a), the model acquired with the portable scanner is decomposed to define a plurality of dental models, each of which is then successively corrected and / or simplified, preferably as described above;

[0074] - The method comprises the following steps after step a):

[0075] b) determining at least one value of a size parameter or "size value" of the updated model, and / or at least one value of an appearance parameter or "appearance value" of the updated model;

[0076] - in step b), defining more than two dimension values ​​(preferably sufficient dimension values) to define the spatial position of at least one point of the updated model (preferably more than 10, more than 100, more than 500 points of the updated model);

[0077] -Size parameters are selected from

[0078] - Updated model dimensions;

[0079] - distances of notable points of the updated model from a reference system that is preferably fixed relative to the updated model (preferably a reference model arranged in a standardized configuration like the updated model), and

[0080] - parameters derived from one or more dimensions of the updated model and / or from one or more distances of one or more notable points of the updated model from said reference system;

[0081] - an appearance parameter selected from the group consisting of color, reflectivity, transparency, reflectance, hue, translucency, opalescence, an index of the presence of tartar, plaque or food on the teeth;

[0082] - to determine said dimension values, measuring the distances between points of the updated model and a reference model arranged in the same standardized configuration as the updated model;

[0083] - The reference model is preferably

[0084] - a model of the updated object obtained by scanning, preferably with a portable scanner or with a professional scanner, preferably more than 2 weeks, 4 weeks, 6 weeks, 2 months, 3 months and / or less than 6 months before the moment of updating, or

[0085] - an updated model of the object, which simulates the shape of said object as expected for the moment of update, and which is preferably implemented at a moment greater than 2 weeks, 4 weeks, 6 weeks, 2 months, 3 months and / or less than 6 months before the moment of update, or

[0086] - an updated model of the object, which simulates the shape of said object as expected for a reference moment after or before the moment of updating, the time interval between the moment of updating and the reference moment preferably being greater than one week, more preferably greater than 2 weeks, 4 weeks, 6 weeks, 2 months and / or less than 6 months,

[0087] The model has preferably been generated more than 2 weeks, more than 4 weeks, more than 6 weeks, more than 2 months or more than 3 months before the time of updating, or

[0088] - a historical model selected from a historical repository that includes models representing objects related to the update

[0089] more than 1,000, preferably more than 10,000, preferably more than 100,000 history models of the same type of object, the selection preferably being guided in such a way that the selected history model is the history model having the shape that is closest to the updated model, or

[0090] - a model obtained by statistically processing the historical models in the history library, preferably in such a way that the model obtained by the statistical processing represents a population of individuals;

[0091] - The method comprises the following steps after step b):

[0092] c) Use dimensional values ​​and / or appearance values ​​to:

[0093] - detecting or assessing the position or shape of a tooth, and / or a change in the position or shape of a tooth, and / or a rate of change in the position or shape of a tooth, and / or

[0094] - detecting or assessing the position or shape of an orthodontic appliance, and / or a change in the position or shape of an orthodontic appliance, and / or a rate of change in the position or shape of an orthodontic appliance, and / or

[0095] - measure changes in the shape of the patient's teeth between two dates, and / or

[0096] - In dental clinics;

[0097] - In step c), the size value and / or appearance value is used

[0098] - Detect or evaluate the location or shape of tooth stains or cavities:

[0099] -Monitoring tooth eruption, and / or

[0100] - Detect recurrent or abnormal tooth position, and / or

[0101] - Detect tooth erosion, and / or

[0102] - follow the opening or closing of at least one gap between two teeth, and / or - check the stability or changes of the bite,

[0103] - Tracking the movement of teeth to a predetermined position, and / or

[0104] - Detect or evaluate detached orthodontic bands or appliances,

[0105] - Optimize the appointment date with the dental professional, and / or - Assess the orthodontic index, in particular, selected from the orthodontic index listed in the definition of orthodontic index below

[0106] An index, preferably an orthodontic index indicating whether

[0107] - The user's canines have achieved a Class I occlusion, and / or

[0108] - The user's molars have achieved Class I occlusion, and / or

[0109] - The patient's anterior space is closed, and / or

[0110] - All spaces created by tooth extractions are closed, and / or

[0111] - the user has a normal overbite, preferably between 1 mm and 3 mm, and / or

[0112] - the user has a normal overbite, preferably between 1 mm and 3 mm, and / or

[0113] - Midline shift of the upper and lower dental arches, and / or

[0114] - The user has no lateral displacement of the upper dental arch relative to the lower dental arch, and / or

[0115] - No tooth movement was detected during the last two examinations, and / or

[0116] - All the baby teeth have fallen out,

[0117] or to quantitatively evaluate and / or assess the time evolution of orthodontic indices for:

[0118] - The type of bite of the canines, and / or

[0119] - The type of occlusion of the molars, and / or

[0120] - The patient's anterior tooth spacing, and / or

[0121] -Gaps created by tooth extraction, and / or

[0122] - Overlay, and / or

[0123] - Overbite, and / or

[0124] - displacement between the midlines of the upper and lower dental arches, and / or

[0125] - lateral displacement of the upper dental arch relative to the lower dental arch, and / or

[0126] - Tooth movement during the last two examinations, and / or - Assessment of effectiveness of active orthodontic treatment, and / or

[0127] - measure the activity of active orthodontic appliances; and / or

[0128] - measure the efficiency loss of passive orthodontic appliances; and / or

[0129] - comparing the positioning of the user's teeth at the updated moment with the positioning of said teeth represented by a theoretical target model (preferably an intermediate model representing said teeth in the expected position) according to a treatment plan for a final or intermediate stage of orthodontic treatment; and / or

[0130] - assessing the need for correction or adaptation of orthodontic treatment, for example by designing and manufacturing a new range of orthodontic appliances as part of orthodontic treatment using orthodontic appliances or by changing the type of orthodontic treatment (e.g. from brackets to appliances or vice versa); and / or

[0131] - measuring the change in the shape of the patient's teeth between two dates separated by the occurrence of an impact on the teeth or by the application of a dental device intended for the treatment of sleep apnea or by the occurrence of an implant in the patient's mouth;

[0132] - In step a), the model acquired using the mobile phone is decomposed to define a plurality of tooth models, and then said step b) is performed to define at least one dimension value for each tooth model defined as an updated model for said step b);

[0133] - in step a), the user preferably uses the same mobile phone to capture said captured model and one or more updated images, preferably color photographs, preferably in realistic colors, and

[0134] In step b), information related to the size and / or the appearance of one or more objects, preferably teeth, represented on the updated image is determined and said information is then used to supplement and / or correct said size values ​​and / or said appearance values ​​determined from the updated model;

[0135] - In step a), the acquired model comprises less than 500 points.

[0136] The present invention also relates to:

[0137] a computer program, in particular a dedicated mobile phone application, comprising program code instructions for performing step a), and preferably step b), and preferably step c), when said program is executed by a computer,

[0138] - a data medium on which such a program is recorded, such as a memory or a CD-ROM, and

[0139] - A portable scanner, in particular one integrated in a mobile phone, in which such a program is loaded.

[0140] Therefore, the present invention relates to a portable scanner, preferably integrated into a mobile phone, which is suitable for implementing the acquisition in step a), and preferably implementing one or more correction and / or simplification processes described in the present specification, and preferably implementing step b), and more preferably implementing step c).

[0141] definition

[0142] The term "user" is intended to refer to any person for whom the method according to the invention is implemented, whether that person is ill or not, or is undergoing orthodontic treatment or not.

[0143] The term "dental care professional" refers to anyone qualified to provide dental care and includes, among other things, orthodontists and dentists.

[0144] "Orthodontic treatment" is all or part of treatment designed to modify the shape of the dental arch (active orthodontic treatment) or to maintain the shape of the dental arch, particularly after the active orthodontic treatment has ended (passive orthodontic treatment).

[0145] Orthodontic indices are composite measures of the shape and / or shape changes of the dental arches. These orthodontic indices may be specific to one or both arches ("inter-arch" indices). Examples include:

[0146] Overbite, overbite, crowding (especially Nance index), deviation of the midline between the incisors, type of canine and / or molar occlusion, irregularity index (especially Little index), anterior open bite, lateral open bite, posterior lingual cross bite, posterior buccal joint inversion, ideal arch length, presence or absence of interdental space, Spee curve flattening index, presence of significant rotation on some teeth, for example greater than 10°,

[0147] and combinations of these indices and variations thereof. Examples of orthodontic indices are those used to define the American Board of Orthodontics "ABO Discrepancy Index".

[0148] An "orthodontic appliance" is a device worn or intended to be worn by a user. An orthodontic appliance may be used for therapeutic or preventive treatment, as well as for aesthetic purposes. In particular, an orthodontic appliance may be an arch and bracket appliance, or an orthodontic brace, or an auxiliary appliance of the Carrière Motion type.

[0149] "Arch" or "dental arch" means all or part of a dental arch.

[0150] An "image" is a two-dimensional digital representation, such as a photograph or a frame from a video. An image is made up of pixels.

[0151] The term "model" refers to a three-dimensional digital model. A model is constructed from a set of voxels. The model typically comprises a grid of points connected by line segments, i.e. a collection of triangles.

[0152] A "tooth model" is a three-dimensional digital model of teeth. The dental arch model can be cut to define a tooth model of at least some (preferably all) of the teeth represented in the dental arch model. Thus, the tooth model is a model within the dental arch model.

[0153] A "dental arch model" is a model representing at least a portion of a dental arch, preferably at least 2 teeth, more preferably at least 3 teeth, most preferably at least 4 teeth.

[0154] A model, in particular a model of a dental arch or teeth, is "hyper-realistic" when the viewer has the impression of looking at the modeled object itself. In particular, the color of the model is the color of the object being modeled.

[0155] By "original" model is meant a model resulting from a scan, which may have been corrected according to the invention, but whose colors have not been modified to make it hyper-realistic.

[0156] The "type" of a modeled object (particularly of an updated object) defines the nature of the object. In particular, an object may be of type "tooth" or "dental arch" or "gingiva". An object may also be a subgroup of teeth, such as a group of incisors or a group of teeth with one or more tooth numbers, or a subgroup of a dental arch, such as the upper dental arch.

[0157] A "classification criterion" is a property of a modeled object (in particular a dental arch or a tooth) which enables the modeled object to be classified. For example, the classification criterion may be an occlusal class, a size range of the modeled object (e.g. height, width, concavity, intercanine distance, interpremolar width, intermolar width, arch length or arch depth, arch circumference), age, sex, pathology or orthodontic treatment of the person who owns the modeled object, an orthodontic index (in particular selected from the orthodontic indices listed above), or a combination of these criteria.

[0158] In particular, the use of a classification criterion makes it possible to select modeled objects having similar or identical properties. Advantageously, this makes it possible to create a learning library appropriately adapted to the objects that the neural network is intended to process. For example, if a neural network is intended to correct a tooth model representing a tooth with number 14, it is preferred to train the neural network with a training library containing only records related to tooth number 14. The tooth number is then used as a classification criterion.

[0159] A "standardized configuration" is a positioning of a model in space according to a predetermined orientation and at a predetermined scale. In order to compare the shapes of two models representing an object (e.g., a dental arch or a tooth), the two models may be arranged in a standardized configuration. Standardized methods for arranging models and determining the size of the models according to a standardized configuration are well known. One way to compare the shapes of two models is to use an iterative closest point search algorithm (ICP, described at https: / / fr.wikipedia.org / wiki / Iterative_Closest_Point).

[0160] "Decomposing" the dental arch model into "tooth models" is the operation of delimiting and making autonomous the tooth representations (tooth models) in the dental arch model. Computer tools can be used to manipulate the tooth models in the dental arch model. An example of software for manipulating the tooth model and creating a treatment plan is the program Treat described at https: / / en.wikipedia.org / wiki / Clear_aligners#cite_note-invisalignsystem-10.

[0161] "Statistical processing" when applied to a data set enables us to determine a characteristic property of that set, such as the mean, standard deviation or median. Statistical processing algorithms are well known to those skilled in the art.

[0162] "Meta-heuristic" methods are well-known optimization methods. In the context of the present invention, these methods are preferably selected from the group formed by:

[0163] - an evolutionary algorithm, preferably selected from the group consisting of evolutionary strategies, genetic algorithms, differential evolution algorithms, distribution estimation algorithms, artificial immune systems, shuffled complex evolutionary algorithm path rewiring, simulated annealing, ant colony algorithms, particle swarm optimization algorithms, tabu search and GRASP methods;

[0164] - Kangaroo algorithm,

[0165] -Fletcher-Powell method,

[0166] - Noise injection method,

[0167] - Random tunneling,

[0168] - Randomly restart the hill climbing,

[0169] - the mutual entropy method, and

[0170] - Hybrid approaches between the above mentioned metaheuristics.

[0171] The measurement of the difference or distance between two objects is called a "match" or "fit." The "best fit" is when this difference is minimized.

[0172] A "neural network" or "artificial neural network" is a collection of algorithms well known to those skilled in the art. In order to be operational, a neural network must be trained from a training library through a learning process known as "deep learning".

[0173] A "learning library" is a database of computer records suitable for training a neural network. The quality of the analysis performed by the neural network depends directly on the number of records in the training database. Typically, the learning library includes more than 1,000, preferably more than 10,000 records.

[0174] The training of the neural network is adapted to the objective pursued and does not present any particular difficulty to a person skilled in the art. Training the neural network consists in exposing it to a training library containing information about a first object and a second object which it must learn to "match", i.e. to connect them to one another.

[0175] The training may be based on a "paired" learning library consisting of "pairs" of records, i.e., each "paired" record comprises a first object for input to the neural network and a corresponding second object for output from the neural network. We also say that the inputs and outputs of the neural network are "paired." Training the neural network with all of these pairs teaches the neural network to provide corresponding objects similar to the second object from objects similar to the first object.

[0176] The paper “Image-to-Image Translation with Conditional Adversarial Networks” by Phillip Isola, Jun-Yan Zhu, Tinghui Zhou, and Alexei A. Efros of the Berkeley AI Research (B AIR) Lab at the University of California, Berkeley, demonstrates the use of a paired learning library.

[0177] The function of a "reference frame" is to serve as a basis for measuring one or more distances. The reference frame may be, for example, a three-dimensional orthogonal reference frame. The three-dimensional reference frame is preferably fixed relative to the model in question. For example, if the model represents a dental arch, the model may be derived from the center of the user's mouth. In particular, the three-dimensional reference frame is preferably independent of the position and orientation of the portable scanner.

[0178] The dimensions of the dental arch (length, width, height) are usually measured with the dental arch in a horizontal plane. Then, the height direction Y is the vertical direction. The width direction X is the lateral direction of the user, extending from the right to the left of the user. The length direction Z is the depth direction of the user, extending from the front to the back of the user.

[0179] The dimensions of a tooth (length, width, height) are usually measured with the dental arch in a horizontal plane. The height direction Y' is then the vertical direction. The width direction X' is the direction perpendicular to the height direction of the largest dimension of the tooth when viewed from the front. The length direction Z' is perpendicular to the directions Y' and X'.

[0180] According to the international practice of the FDI World Dental Federation, each tooth in the dental arch has a predetermined number. Figure 6 The tooth numbering defined by this convention is shown.

[0181] "Noteworthy points" are points on the dental arch or tooth model that can be identified, such as the apex of a tooth or the tip of a cusp, an interdental (i.e., a tooth's contact with an adjacent tooth) point (such as the mesial or distal point of the incisal edge of a tooth), or a point at the center of a crown, or "center of gravity."

[0182] The "tilt angle" is the orientation of the optical axis of the portable scanner relative to the user during the acquisition of the phantom in step a).

[0183] A 3D scanner or "scanner" is a device that produces a model of a tooth or dental arch. Traditionally, this scanner uses structured light to create a 3D model from different images, preferably by matching specific points on these images.

[0184] More specifically, a portable scanner projects structured light onto the patient's teeth while acquiring the image. The scanner can project a light pattern onto the teeth. Distortion of the pattern allows for a spatial interpretation of the scene.

[0185] Traditional techniques include 1D or 2D pattern projection, multi-ray laser triangulation (MLT), digital fringe and phase modulation.

[0186] As an alternative or in addition to structured light projection, a portable scanner projects modulated light onto the patient's teeth while acquiring the image. The projected light then changes, and the scanner's camera measures the change in reflected light over time to deduce the distance traveled by the reflected light. Among the conventionally used techniques, phase modulation techniques are particularly noteworthy.

[0187] Use image analysis to build the model.

[0188] The images may be of the same type as those acquired by conventional intraoral 3D optical scanners.

[0189] The images are representations of the observed scene (in this case the patient's teeth), but the properties of these images are specific to the properties of the light source illuminating the scene. Preferably, the images are not realistic representations of the scene, as a person would be observing the scene directly.

[0190] The maximum shape difference between a model acquired with a scanner and the scanned full-size object is inversely proportional to the scanner's performance. This is called the scanner's "acquisition resolution" or "precision". The smaller the resolution, the more faithful the model is to reality.

[0191] A laser remote sensor is particularly suitable for the present invention as it enables an accurate dental arch model to be acquired extraorally by the patient himself with the laser projected directly onto the patient's teeth.

[0192] The accuracy of a professional scanner is preferably less than 5 / 10 mm (i.e. the maximum shape difference between the model acquired using the scanner and the actual object scanned at true scale is less than 5 / 10 mm), preferably less than 3 / 10 mm, preferably less than 1 / 10 mm, preferably less than 1 / 50 mm, more preferably less than 1 / 100 mm and / or greater than 1 / 500 mm.

[0193] "Mobile phone" or "cellular phone" is similar Such a device usually weighs less than 500g or less than 200g and is equipped with a camera including a lens for taking videos or photos, or even a scanner for acquiring three-dimensional digital models. The mobile phone can also exchange data with another device more than 500km away from the mobile phone and can display on the screen the video, photos or models that the mobile phone has acquired.

[0194] A retractor (or dental retractor) is a device used to pull the lips back. The retractor comprises upper and lower flanges and / or right and left flanges extending around the retractor opening and intended to be inserted between the teeth and the lips. In the operating position, the user's lips rest on these edges so that the teeth are visible through the retractor opening. Thus, the retractor allows viewing of the teeth without being obstructed by the lips.

[0195] However, the teeth do not rest on the retractor, so that by turning the head relative to the retractor, the user can change the teeth visible through the retractor opening. The user can also change the spacing between their dental arches. In particular, the retractor does not press on the teeth to expand the upper and lower jaws apart, but rather presses on the lips.

[0196] In one embodiment, the retractor is configured to elastically spread the upper and lower lips apart to expose the teeth visible through the retractor opening.

[0197] In one embodiment, the retractor is configured such that the distance between the top edge and the bottom edge and / or between the right edge and the left edge is constant.

[0198] Retractors are described, for example, in PCT / EP2015 / 074896, US 6,923,761 or US 2004 / 0209225.

[0199] The "service position" is the position where the user acquires the model acquired in step a). When a support frame is used to rigidly fix the portable scanner, the support frame is partially inserted into the user's mouth, such as Figure 2 and Figure 3 shown.

[0200] The "closed mouth" position is a bite position in which the teeth of the patient's upper and lower arches are in contact. The "open mouth" position is a position in which the teeth of the patient's upper and lower arches are not in contact.

[0201] The method according to the invention (excluding the acquisition operation with the portable scanner) is implemented by a computer (preferably exclusively by a computer).

[0202] "Computer" refers to a computer processing unit, which comprises a group of several machines with computer processing capabilities. In particular, the unit may be integrated into a portable scanner, or into a mobile phone comprising a portable scanner, or a PC-type computer or a server, for example a server remote from the user, such as a computer in the "cloud" or located in the dental professional's clinic. In this case, the mobile phone and the computer comprise communication means for exchanging information with each other, in particular for sending an updated, optionally corrected and / or simplified model and / or one or more dimensional values ​​determined according to the invention.

[0203] Typically, a computer includes a processor, a memory, a human-computer interface (usually including a screen), and a computer that can communicate with the Internet, WIFI, The computer may be connected to a communication module of a telephone network or a telephone network. The software configured to implement the method of the present invention is loaded into the memory of the computer. The computer may also be connected to a printer.

[0204] For the sake of clarity, "first" and "second" are used.

[0205] Similarly, for clarity:

[0206] - The term "basic" refers to the model used in the preferred simplified method;

[0207] - the term "reference" refers to the model used in step b) for evaluating the dimensional or appearance values, or to the moment at which an object modeled by the reference model is expected to have the shape or appearance of this model;

[0208] - the term "calibration" refers to the model or moment used in the preferred calibration method;

[0209] - the term "updated" refers to step a), and in particular to the model resulting from step a);

[0210] - the term "historical" refers to one or more models acquired before the moment of updating, in particular modeling the dental arch or teeth of a "historical" person different from the user;

[0211] - "Best" refers to the model in the model ensemble that has a shape closest to the updated model.

[0212] “Vertical”, “horizontal”, “right”, “left”, “in front” or “from the front”, “behind”, “above”, “below” mean that the user is standing upright.

[0213] Unless otherwise indicated, "including" or "comprising" or "having" should be interpreted in a non-limiting manner. BRIEF DESCRIPTION OF THE DRAWINGS

[0214] Other features and advantages of the present invention will become apparent from the following detailed description and from an examination of the accompanying drawings, in which:

[0215] -[ Figure 1 ] Figure 1 An example of a kit according to the invention is schematically shown;

[0216] -[ Figure 2 ] Figure 2 Schematically shows a kit according to the invention in a service position, with a user viewing it from the front;

[0217] -[ Figure 3 ] Figure 3 Schematically shows a kit according to the invention in a service position, with a user viewing it from the side;

[0218] -[ Figure 4 ] Figure 4 Models acquired at three different acquisition resolutions are shown;

[0219] -[ Figure 5 ] Figure 5 is an example of an acquired model after a process of decomposing a tooth model; the example of a tooth model is dark grey;

[0220] -[ Figure 6 ] Figure 6 The dental tooth numbers are shown;

[0221] -[ Figure 7 ] Figure 7 The acquisition method according to the present invention is shown;

[0222] -[ Figure 8 ] Figure 8 A first correction method according to the present invention is shown;

[0223] -[ Fig. 9 ] Fig. 9 A second correction method according to the present invention is shown;

[0224] -[ Fig.10 ] Fig.10 An example of a portable scanner in one embodiment of the present invention is schematically shown;

[0225] -[ Fig.11 ] Fig.11 Several images are shown that provide additional data;

[0226] -[ Fig.12 ] Fig.12 An example of a device for implementing the image acquisition method according to the present invention is schematically shown.

[0227] In the various drawings, the same reference numbers are used to indicate similar or identical objects. DETAILED DESCRIPTION

[0228] like Figure 7 As shown, the object of the method according to the invention is to quickly provide a digital three-dimensional model of a user's dental arch or a part thereof, ie an "updated model".

[0229] In step a), at the time of updating, the user uses the portable scanner 6 to generate a “captured model”.

[0230] Preferably, the acquired model represents at least 2, preferably at least 3, more preferably at least 4 teeth, preferably all teeth in the dental arch.

[0231] A portable scanner is an autonomous scanner, in particular because it integrates its own power source, usually a battery, and because its weight allows it to be operated by hand.

[0232] Preferably, the portable scanner weighs less than 1 kg, preferably less than 500 g, more preferably less than 200 g, and / or more than 50 g.

[0233] Preferably, the maximum dimension of the portable scanner is less than 30 cm, 20 cm or 15 cm and / or greater than 5 cm.

[0234] The portable scanner preferably has an acquisition resolution of less than 10 mm, preferably less than 5 mm, preferably less than 3 mm, preferably less than 2 mm, preferably less than 1 mm, preferably less than 1 / 2 mm, preferably less than 1 / 5 mm, preferably less than 1 / 10 mm.

[0235] The portable scanner is preferably configured such that the acquired model comprises more than 5,000 and / or less than 200,000 or less than 150,000 points.

[0236] Figure 4 Examples of dental arch models 8 featuring 5,000, 11,500 and 154,000 points respectively acquired using a portable scanner are shown.

[0237] The portable scanner 6 may be integrated into a mobile phone 12, such as Figure 1 As shown, or communicate with a mobile phone. Therefore, step a) is easy for the user to implement. The mobile phone can also be used to transmit the updated model to a remote computer.

[0238] The moment of updating may be during orthodontic treatment being undergone by the user or outside of orthodontic treatment.

[0239] In step a), the portable scanner is preferably hand-held by the user. Preferably, the portable scanner is not fixed, for example by means of a structure resting on the ground, such as a tripod. Preferably, the user's head is not fixed.

[0240] In one embodiment, the user scans the dental arch without using any device other than the portable scanner.

[0241] In a preferred embodiment, the user uses a tool to free their lips and better expose their dental arch to the portable scanner. The tool can be, for example, a spoon inserted into the mouth.

[0242] In one embodiment, the user uses a retractor and / or mouth support frame that they partially insert into their mouth.

[0243] Portable Scanner Support

[0244] In a particularly advantageous embodiment, in step a), the user uses a portable scanner 6 and a support frame 14 ( Figure 1 ) of the kit 10, the support frame makes it possible to simultaneously

[0245] - expanding the user's lips to expose the teeth, and

[0246] - Facilitates the positioning and orientation of the portable scanner 6 relative to the teeth.

[0247] The support frame 14 preferably has the general shape of a tubular body, one opening of which (referred to as the "oral opening" Oo) is intended to be introduced into the patient's mouth and the opposite opening of the tubular body (referred to as the "acquisition opening") faces the lens of the portable scanner, which is rigidly (preferably removably) attached to the support frame 14.

[0248] Preferably, the acquisition opening also faces a portable scanner flashlight, which can be used to illuminate the user's teeth during acquisition.

[0249] The support frame 14 makes it possible to define the spacing between the portable scanner and the oral opening Oo, as well as the orientation of the portable scanner relative to the oral opening. Advantageously, in the service position, the data acquired by the portable scanner 6 through its lens, acquisition opening and oral opening are thus acquired at a predetermined distance from the teeth of the user and according to a predefined orientation. Preferably, the support frame is configured so that this spacing and orientation are constant.

[0250] Preferably, the support frame 14 comprises:

[0251] a tubular spacer 16 defining the oral opening Oo and preferably comprising a radially outwardly extending flange 22 at the periphery of the oral opening Oo for insertion between the lips and teeth of a user, and

[0252] - an adapter 18 to which the portable scanner 6 is attached, for example clamped between two jaws 241 and 242, such as Figure 1 As shown, the adapter 18 is rigidly (preferably removably, for example, by means of a clip 20) attached to the spacer 16, or is integral with the retractor,

[0253] This allows the portable scanner camera to "see" the mouth opening.

[0254] The maximum height h of the edge 22 22 Preferably larger than 3 mm and smaller than 10 mm.

[0255] To acquire the acquired model, the user attaches the tubular spacer 16 to the adapter 18 with the aid of the clip 20, and then attaches the portable scanner to the adapter 18 so that the portable scanner can scan the tubular spacer 16 and the adapter 18. The user then introduces the end of the tubular spacer opposite the portable scanner into their mouth, inserting the rim 22 between their lips and teeth. In this way, the lips rest on the outside of the tubular spacer 16, providing a clear view of the teeth through the oral opening Oo.

[0256] In the service location obtained, such as Figure 2 and Figure 3 As shown, the teeth do not rest on the support frame, so that the user U can modify the teeth visible to the portable scanner through the mouth opening by turning the head relative to the support frame. The user can also change the spacing between their dental arches. In particular, the support frame separates the lips but does not press on the teeth, thereby moving the upper and lower jaws apart.

[0257] The acquired model may fully or partially represent one or both dental arches.

[0258] Decomposing the collected model

[0259] In one embodiment, the dental arch model acquired with the portable scanner is decomposed, preferably defining at least one tooth model 30. In one embodiment, the updated model is thus reduced to a portion of the acquired model, preferably to a tooth model.

[0260] Preferably, steps b) and c) are then performed successively for each tooth model.

[0261] The model may be decomposed using any known decomposition method.

[0262] Correcting an updated model derived from the decomposition of the acquired model involves modifying the updated model so that it better conforms to the object it models. To this end, the resolution of the model may be increased, and / or the model may be added, and / or the model may be given more realistic colors, for example to make it hyper-realistic, and / or the model may be cleaned. Model cleaning consists of removing parts of the model that do not model the target object, for example by removing representations of orthodontic attachments when the target object is a tooth, or removing defects resulting from the acquisition operation, in particular cleaning up artifacts caused by saliva during acquisition.

[0263] Correction

[0264] The updated model is preferably computer processed for calibration.The updated model may be calibrated after or before simplification.

[0265] In a preferred embodiment, Figure 8 As shown, the updated model is compared with the "corrected model" and then a correction is made based on the results of the comparison.

[0266] Preferably, when the model to be corrected is a tooth model, the following steps are taken:

[0267] i) Create a historical library of more than 1,000 tooth models (called “historical tooth models”),

[0268] And assign a tooth number to each historical tooth model;

[0269] ii) analyzing the tooth model to be corrected so as to determine the tooth number modeled by the tooth model to be corrected;

[0270] iii) searching the historical tooth model in the historical library for a historical tooth model having the same number and having the greatest similarity to the tooth model to be corrected, or the "best tooth model";

[0271] iv) modifying the tooth model to be corrected based on the information about the optimal tooth model, which may include replacing the tooth model to be corrected with the optimal tooth model.

[0272] In step i), a history library is created which preferably comprises more than 2,000, preferably more than 5,000, more preferably more than 10,000 and / or less than 10,000,000 historical dental models.

[0273] In particular, a historical dental model may be obtained from a CT scan model of a dental arch of a "historical" patient. The dental arch model may be cut to separate the tooth representations, i.e. the tooth models, such as Figure 5 shown.

[0274] The history library thus contains the historical tooth models and the numbers of the teeth modeled by these historical tooth models.

[0275] In step ii), the tooth model to be corrected is analyzed to determine its number.

[0276] Traditionally, tooth numbers are assigned according to a standard rule. Knowing this rule and the number of the model tooth is sufficient to determine the number of other tooth models.

[0277] In a preferred embodiment, the shape of the tooth model to be corrected is analyzed to define its number. This shape recognition is preferably performed using a neural network.

[0278] Preferably, a neural network is used, which is preferably selected from the group consisting of “object detection networks”, for example selected from the group consisting of R-CNN (2013), SSD (Single Shot Multibox Detector: Object Detection Network), Faster R-CNN (Faster Region-based Convolutional Network Approach: Object Detection Network), Faster R-CNN (2015), SSD (2015), RCF (Richer Convolutional Features for Edge Detection) (2017), SPP-Net (2014), OverFeat (Sermanet et al.) (2013), GoogleNet (Szegedy et al.) (2015), VGGNet (Simonyan and Zisserman) (2014), R-CNN (Girshick et al.) (2014), Fast R-CNN (Girshick et al.) (2015), ResNet (He et al.) (2016), Faster R-CNN (Ren et al.) (2016), FPN (Lin et al.) (2016), YOLO (Redmon et al.) (2016), SSD (Liu et al.) (2016), ResNet v2 (He et al.) (2016), R-FCN (Dai et al.) (2016), ResNeXt (Lin et al.) (2017), DenseNet (Huang et al.) (2017), DPN (Chen et al.) (2017), YOL09000 (Redmon and Farhadi) (2017), Hourglass (Newell et al.) (2016), MobileNet (Howard et al.) (2017), DCN (Dai et al.) (2017), RetinaNet (Lin et al.) (2017), Mask R-CNN (He et al.) (2017), RefineDet (Zhang et al.) (2018), CascadeRCNN (Cai et al.) (2018), NASNet (Zoph et al.) (2019), CornerNet (Law and Deng) (2018), FSAF (Zhu et al.) (2019), SENet (Hu et al.) (2018), ExtremeNet (Zhou et al.) (2019), NAS-FPN (Ghiasi et al.) (2019), Detnas (Chen et al.) (2019), FCOS (Tian et al.) (2019), CenterNet (Duan et al.) (2019), EfficientNet (Tan and Le) (2019), AlexNet (Krizhevsky et al.) (2012), CBNet (2020), Point-GNN (2020), MDFN (2020), CADN (2021).

[0279] Preferably, the neural network is trained by providing as input a tooth model and as output the associated tooth numbers. The neural network thus learns the tooth numbers of the tooth model provided as input to the neural network.

[0280] Then, the tooth model to be corrected can be modified based on the historical tooth model having the same number.

[0281] In step iii), the historical tooth model with the same number as the tooth model to be corrected is searched in the historical library to find the tooth model with the greatest similarity to the tooth model to be corrected. This historical tooth model is called the "optimal tooth model".

[0282] "Closeness" is a measure of the shape difference between the historical dental model and the dental model to be corrected. The shape difference may be, for example, the average distance between the historical dental model and the dental model to be corrected after the historical dental model and the dental model to be corrected have been arranged in a standardized configuration.

[0283] Preferably, the maximum closeness or "best fit" is considered to be achieved when the cumulative Euclidean distance between the points of the historical dental model and the points of the dental model to be corrected is minimal.

[0284] In step iv), the tooth model to be corrected is modified based on the information about the best tooth model used as the correction model.

[0285] For example, those areas of the tooth model to be corrected which are more than 1 mm away from the optimal tooth model in the standardized configuration may be replaced by areas of the optimal tooth model facing these areas, and / or

[0286] The "blank" areas of the tooth model to be corrected (ie the undefined areas facing the non-blank areas of the optimal tooth model) can be replaced by these areas of the optimal tooth model.

[0287] Modifying the tooth model to be corrected may also involve replacing the tooth model to be corrected with the optimal tooth model.

[0288] Preferably, steps i) to iv) are performed for each tooth model cut from the acquired model.

[0289] The above process can be applied to the updated model of the dental arch. In steps ii) and iii), the classification criteria of the updated model are adjusted accordingly. As an alternative to the tooth numbering, the classification criteria can be, for example, one or more attributes related to one dental arch (such as dental arch width), or one or more attributes related to both dental arches. In the definition of the classification criteria, the classification criteria can in particular be selected from those listed above.

[0290] The updated model can be submitted to a neural network trained for this purpose with the aid of a training library. In particular, the neural network can be selected from the following networks: Shape Inpainting Using 3D Generative Adversarial Networks and Recurrent Convolutional Networks (2017), Deformable Shape Completion Using Graph Convolutional Autoencoders (2018), Learning 3D Shape Completion with Weak Supervision (2018), PCN: Point Completion Networks (2019), TopNet: Structured Point Cloud Decoder (2019), RL-GAN-Net: Reinforcement Learning Agent Controlled GAN Networks for Real-Time Point Cloud Shape Completion (2019), Cascaded Refinement Networks for Point Cloud Completion (2020), PF-Net: Point Fractal Networks for 3D Point Cloud Completion (2020), Point Cloud Completion via Jump Attention Networks with Hierarchical Folding (2020), GRNet: Mesh Residual Networks for Dense Point Cloud Completion (2020), and Style-Based Point Generators with Adversarial Rendering for Point Cloud Completion (2021).

[0291] For example, each record in the learning database may include:

[0292] - an incomplete model of an object, such as

[0293] dental arch, or

[0294] Tooth models, and

[0295] -Same model, but complete.

[0296] Preferably, the objects modeled in the records belong to the same category defined by the classification criteria. For example, if the objects are teeth, the tooth numbers of the tooth models are preferably the same for all records in the learning database.

[0297] Preferably, a neural network specialized for image generation is used, such as:

[0298] - Cycle-Consistent Adversarial Networks (2017),

[0299] -Enhancing CycleGAN (2018),

[0300] - Deep Photo Style Transfer (2017),

[0301] -FastPhotoStyle (2018),

[0302] -pix2pix (2017),

[0303] - Style-based Generator Architectures for GANs (2018),

[0304] -SRGAN (2018),

[0305] -WaveGAN(2020),

[0306] - GAN-LSTM (2019),

[0307] -CSGAN (2021),

[0308] -DivCo (2021).

[0309] After training with the learning library, the neural network can transform the incomplete model into a complete model by successively providing the incomplete model with the incomplete model for each record and the corresponding complete model as output.

[0310] The full model was used as the “calibrated model”.

[0311] The correction model can be used to perform a quality check on the acquisition of the acquired model, i.e. to check that the acquisition has not generated any defects. A defect is a part of the acquired model that does not correctly represent the dental arch. For example, the model may feature roughness or depressions that do not actually exist (i.e. on the dental arch).

[0312] Correction of the acquired model can also be used to remove such defects caused by the acquisition operation.

[0313] clean

[0314] Preferably, the updated model is cleaned independently of the above modification method (steps i) to iv)).The goal is to process the updated model to remove the representation of the external object and replace it with a surface representing as faithfully as possible the surface of the dental arch covered by the object.

[0315] In a preferred embodiment, Fig. 9 As shown, the updated model is cleaned to remove the representation of the object external to the user (e.g., orthodontic brackets), thereby at least partially masking the object to be modeled (e.g., teeth), by proceeding according to the following steps:

[0316] i')Definition:

[0317] a first determined area, consisting of points or "first determined points" representing the updated model of the object to be modeled (eg a tooth) with an accuracy greater than 90%, and

[0318] - a first uncertainty region, which constitutes the 100% complement of the updated model;

[0319] ii') starting from the first determination zone only, the first determination zone is extrapolated to define a first reconstruction zone in the region of the first uncertainty zone, and then

[0320] definition:

[0321] a second zone of determination, consisting of points of the first zone of uncertainty or "second points of determination" which are separated from the first reconstructed zone by a distance less than a threshold distance; and

[0322] - a second uncertainty region which constitutes the 100% complement of the first uncertainty region;

[0323] iii') extrapolating from the single set a set consisting of the first uncertainty zone and the second uncertainty zone to define a second reconstruction zone in the region of the second uncertainty zone, and then

[0324] -Replace the second uncertainty region with the second reconstructed region in order to obtain a clean updated model.

[0325] These operations have the advantage of removing representations of external objects from the updated model, resulting in a clean updated model that represents the object to be modeled with good accuracy.

[0326] The external object may be all or part of an orthodontic appliance, a crown, an implant, a bridge, an elastic band, or a dental veneer. The external object may also be food, a drop of saliva, or all or part of a tool.

[0327] In step i'), representations of external objects are isolated. Specifically, we identify points in the updated model that are almost certainly representations of points on the dental arch.

[0328] Algorithms for detecting objects in images are well known to the skilled person.Preferably, a neural network is used, which is preferably selected from an "object detection network", such as from the neural networks listed above.

[0329] After training, these neural networks are able to detect those points in the updated model that represent points in the dental arch or "first determined points" with an accuracy threshold greater than or equal to 90%. All of these points (called the "first determined area") form part of the updated model. The points in the updated model that are not in the first determined area collectively form the "first uncertainty area".

[0330] Preferably, the accuracy threshold is greater than 95%, preferably greater than 98%, more preferably greater than 99% and / or less than 99.99%.

[0331] Training a neural network to detect objects in an image presents no difficulty to a person skilled in the art. For example, the neural network may be provided with a dental arch model as input and the same dental arch model as output, on which regions representing the dental arch and regions representing external objects have been identified. The neural network learns how to define these regions on the dental arch model.

[0332] The goal of the following steps is to fill the "first blank area" of the updated model, which first blank area appears when the first uncertainty area is removed.

[0333] In step ii'), the first determined area is used to define a surface that fills the first blank area. This area is called the "first reconstruction area".

[0334] Techniques for implementing this extrapolation are well known. Examples include Holger WENDLAND's Piecewise polynomial, positive definite and compactly supported radial functions of minimal degree. Advances in Computational Mathematics, 1995, Vol. 4, No. 1, pp. 389-396.

[0335] To refine the reconstruction of the dental arch surface hidden by external objects, points of the first uncertainty zone close to the first reconstruction zone are then identified. These points are therefore points in the updated model close to the surface extrapolated from points representing points on the dental arch with virtual certainty.

[0336] These points or "second determined points" in the updated model are also considered to represent points on the dental arch with high accuracy. These points are called "second determined areas". Therefore, these points are points in the updated model that have been discarded by the analysis in step i'), but are retained because they are close to the surface extrapolated from the points that have been retained by the analysis in step i').

[0337] Points in the updated model that do not belong to the first uncertainty region or the second uncertainty region together form a "second uncertainty region".

[0338] The proximity of a point in the first uncertainty zone to the first reconstruction zone can be assessed by measuring the Euclidean distance between the point and the first reconstruction zone. If the distance is less than a threshold distance, the point in the first uncertainty zone is considered to have entered the second uncertainty zone.

[0339] If the model is scale 1, ie represents the modelled object with its actual size, the threshold distance is preferably larger than 0.1 mm and / or smaller than 1 mm.

[0340] The threshold distance may also be determined by analyzing the distribution of said Euclidean distances between points in the first uncertainty zone and the first reconstruction zone, for example as a function of the mean deviation and standard of these distances. For example, a dynamic calculation using a method such as the "3 sigma rule" may be used.

[0341] In step iii'), the goal is to replace the second uncertainty zone with a second reconstructed zone that better matches the dental arch surface. To this end, the first and second determination zones are extrapolated into the area of ​​the second uncertainty zone.

[0342] Of particular note is the fact that the extrapolation is not based on the first determined area alone, but on the first determined area and the second determined area. Tests have shown that this extrapolation produces a second reconstructed area that represents the dental arch surface with a high degree of reliability.

[0343] The extrapolation in step iii') can use the same method as used in step ii'). Different methods can also be used.

[0344] The first determination region and the second determination region and the second reconstruction region constitute an updated, cleaned model, on which representations of external objects have been removed.

[0345] Appearance Correction

[0346] Preferably, the updated model is made hyper-realistic, preferably with the aid of a neural network.

[0347] The updated model can be submitted to a neural network trained for this purpose with the aid of a learning library, as described, for example, in http: / / cs230.stanford.edu / projects_winter_2020 / reports / 32639841.pdf.

[0348] For example, each record in the learning database may include:

[0349] - the original model of the object, e.g.

[0350] dental arch, or

[0351] Tooth models, and

[0352] -Same model, but super realistic.

[0353] The original models are preferably similar in appearance to the updated models.These original models may be scanned, preferably with a scanner identical or similar to the portable scanner used in step a).

[0354] The original model may have been rendered hyper-realistically, for example, by photo-projection.

[0355] Preferably, the objects modeled in the records belong to the same category defined by the classification criteria. For example, if the objects are teeth, the tooth numbers of the tooth models are preferably the same for all records in the learning database.

[0356] Preferably, a neural network specialized for image generation is used, such as:

[0357] - Cycle-Consistent Adversarial Networks (2017)

[0358] -Enhancing CycleGAN (2018)

[0359] - Deep Photo Style Transfer (2017)

[0360] -FastPhotoStyle (2018)

[0361] -pix2pix (2017)

[0362] - Style-based Generator Architectures for GANs (2018)

[0363] -SRGAN (2018).

[0364] After training with the training library, the neural network can transform the original model into a hyper-realistic model by successively providing the original model as input and the hyper-realistic model as output for each record.

[0365] Due to the correction method described above, the updated model may advantageously be transformed into an updated model representing the modeled object (eg a real dental arch) with high fidelity.

[0366] simplify

[0367] Before being used, for example, in step b), the updated, possibly corrected model may be simplified, in particular to facilitate processing in step b). The simplification may also be performed before or after any correction, or between two correction processes.

[0368] The updated, preferably corrected model is preferably displayed on the screen, preferably on the mobile phone screen when the mobile phone is combined with a portable scanner, and / or on a screen in the dental professional's clinic.

[0369] One or more of the above-described decomposition operation and / or correction operation and / or cleaning operation and / or appearance correction operation and / or simplification operation may be

[0370] - is performed in a portable scanner, preferably in a mobile phone that is integrated with the portable scanner or communicates with the acquisition tool, or

[0371] - being carried out in a data processing centre in communication with said mobile phone, to which data processing centre said mobile phone has sent the acquired or updated model.

[0372] In step b), at least one value of a size parameter or "size value" of the updated model and / or at least one value of an appearance parameter or "appearance value" of the updated model is determined.

[0373] Step b) may be implemented in the mobile phone or in a processing centre remote from the mobile phone to which the mobile phone sends the updated model.

[0374] The updated model used in step b) can be

[0375] - an acquired model, i.e. a raw model generated by a portable scanner, or

[0376] a part of the acquired model, for example resulting from a computer decomposition of the acquired model,

[0377] or

[0378] - said model acquired after correction and / or simplification, or

[0379] - said part of the model acquired after correction and / or simplification.

[0380] The Dimension Value is a value that depends on the shape of the updated model. This value is the value of the Dimension Parameter, which can be selected from

[0381] - The dimensions of the updated model, such as arch or tooth width, length or height;

[0382] - the distance of the point in the updated model from the reference frame, or

[0383] -Parameters derived from these dimensions and distances, such as orthodontic index, canine / molar occlusal category, overbite or overbite measurement, tooth number, or indication of the presence or absence of a tooth.

[0384] The dimension value may be measured on the updated model or obtained from one or more measurements made on the updated model.

[0385] For example, we may measure the distance between two teeth, the position of a noteworthy point relative to a reference system (e.g., orthogonal, relative to an actual object (particularly a dental arch or tooth) or fixed relative to another tooth), for example, to assess the alignment of a tooth relative to other teeth, the misalignment of a tooth relative to other teeth or relative to a predetermined position in a reference system, the positioning of one or more teeth relative to a fixed or removable orthodontic appliance located on the teeth or soft tissue, an index of crowding and / or irregularity of a dental arch, misalignment of a tooth relative to other teeth or relative to the gums, deformation of a tooth (e.g., the depth of a cavity), deformation of the gums, the width of a dental arch, or the relative position of one dental arch relative to another.

[0386] The size value may also be a measure of the shape difference between the updated model and the reference model. In particular, the tooth shape and / or position may be compared in the updated model and in the reference model.

[0387] The "Appearance Value" is a value that depends on the appearance of the surface of the updated model. This value is the value of an "Appearance Parameter" that can be selected from color, reflectivity, transparency, reflectance, hue, translucency, opalescence, and an indication of the presence of tartar, plaque or food on the teeth.

[0388] The appearance value may also be a measure of the shape difference between the updated model and the reference model. In particular, the tooth appearance may be compared in the updated model and in the reference model.

[0389] The reference model is selected based on the intended application.

[0390] For example, if the purpose is to check whether a dental condition is normal at the moment of the update, i.e. to verify that the dental condition does not require intervention by a dental care professional, in particular for therapeutic or aesthetic reasons, the reference model can be a model representing the same type of object as the updated object, or even the updated object in a dental condition that was considered normal at the moment of the update.

[0391] The reference model may represent a group of individuals, the group of individuals preferably comprising more than 100 individuals, preferably more than 1000 individuals and / or less than 10,000,000 individuals, e.g.

[0392] - if the updated object is a tooth, then the representation of the tooth from a standard tooth model, or

[0393] - If the updated object is a dental arch, then it represents the dental arch corresponding to the average dental arch shape of all individuals.

[0394] The reference model may be a model that represents an object of the same type as the updated object, preferably the updated object, but whose position and / or shape and / or appearance is the position and / or shape and / or appearance of the updated object as expected at a reference time before or after the moment of the update or simultaneously with the moment of the update.

[0395] In particular, the reference moment may be a stage of orthodontic treatment experienced by the user (eg at the beginning or end of orthodontic treatment, or at an intermediate stage of orthodontic treatment (referred to as an intermediate "set-up" or "stage")).

[0396] The time interval between the updated time and the reference time may be greater than one week, preferably greater than 2 weeks, 4 weeks, 6 weeks, 2 months and / or less than 6 months.

[0397] The reference model may be obtained with the aid of a scanner (eg with a portable scanner of the user, preferably with the aid of a professional scanner), or by construction from photographs of the dental arch and a historical tooth library, as described in EP18184486 (equivalent to US16 / 031,172).

[0398] The reference model is preferably obtained by computer simulation, so that it represents the dental arch in the configuration to be expected at a reference time, in particular at the end of orthodontic treatment or at an updated time.

[0399] For example, the reference model may be generated by modification of an initial model, for example by means of a scan of the user's dental arch, preferably more than one week before the moment of updating, for example at the beginning of orthodontic treatment. The initial model is conventionally decomposed to define the tooth model. The tooth model is then moved to simulate the orthodontic treatment process.

[0400] An example of software for manipulating a tooth model and creating a treatment plan is the program Treat described at https: / / en.wikipedia.org / wiki / Clear_aligners#cite_note-invisalignsystem-10. US5975893A also describes the creation of a treatment plan.

[0401] In one embodiment, the following steps are performed:

[0402] - decomposing a reference model produced before the moment of updating or a reference model of the updated model,

[0403] To generate a tooth model,

[0404] - moving one or more of said dental models without deforming them until a modified model is obtained having the best fit with the updated model or the reference model, respectively,

[0405] - evaluating the difference in position of at least one tooth model between its position in the reference model or the updated model, respectively, and its position in the modified model (determining at least one dimension value).

[0406] In step c), the size values ​​and / or appearance values ​​determined in step b) are used, in particular, to decide whether an action for therapeutic or aesthetic purposes is necessary and / or to help determine such an action.

[0407] The size values ​​and / or appearance values ​​and the preferably updated model may be presented to the user, for example by displaying them on a mobile phone screen of the user.

[0408] Additionally or alternatively, the size values ​​and / or appearance values ​​and preferably the updated model may also be sent to a dental care professional, in particular an orthodontist, preferably via a mobile phone integrated with a portable scanner or communicating with the acquisition tool, preferably over the air, or to a remote computer communicating with the mobile phone.

[0409] Preferably, the size values ​​and / or appearance values ​​are interpreted by a computer, preferably by a mobile phone incorporating a portable scanner, and a recommendation is presented to the user, preferably on a mobile phone screen.

[0410] Use of latest images

[0411] In a particularly advantageous embodiment, in step a), in addition to the updated model, the user also acquires one or more "updated" images, preferably extraorally. Preferably, the user uses a mobile phone which is implemented to acquire the acquired model.

[0412] Preferably, the updated image is a photograph or an image captured from a video. Preferably, the updated image is in full color, preferably true color. Preferably, the updated image depicts the dental arch substantially as seen by an operator of the image acquisition device.

[0413] The information provided by the updated image supplements the information provided by the acquired model. In particular, the information may relate to the size and / or appearance of one or more objects (preferably teeth) represented in the updated image. In particular, the analysis of the updated image (preferably by a computer) may be used to confirm and / or correct the size values ​​and / or appearance values ​​determined from the updated model and / or to supplement the experience learned from the updated model.

[0414] For example, an updated model may detect a cavity on the surface of a tooth, and an updated image may show a darker area at the location of the cavity. The updated image confirms the presence of the cavity. The updated image also allows you to confirm your location. By analyzing the model and the updated image, cavities can be detected and monitored.

[0415] The updated image can also reliably provide information about the appearance of the teeth, such as the color of the teeth. When projected onto the updated model, the updated image allows the surface of the updated model to be colored in a highly realistic manner.

[0416] Preferably, multiple updated images are acquired at different angles (i.e., at different orientations of the acquisition device relative to the user's mouth). For example, the updated image set may include 6 images representing the dental arch "front view", "right front view", "right view", "left front view", "left view" and "bottom view" respectively.

[0417] Preferably, at least one updated image is acquired facing the user (front view). Preferably, at least one updated image is acquired from the right of the user and at least one updated image is acquired from the left of the user.

[0418] The set of updated images preferably comprises more than two, preferably more than three, preferably more than 5, preferably more than 6 and / or less than 30, preferably less than 20, preferably less than 15, preferably less than 10 updated images.

[0419] In one embodiment, the updated images are processed to generate a so-called correction model and / or a so-called reference model. Any conventional technique may be used for this purpose.

[0420] By acquiring two models at the time of update, namely the updated model and the model obtained from the updated image, and then comparing these models, full use can be made of the 3D representation and the 2D representation provided by the portable scanner and the image acquisition device, respectively.

[0421] The method may be implemented independently of any orthodontic treatment, in particular to monitor that their position and / or shape is not "abnormal" (i.e. when the teeth do not meet treatment or aesthetic criteria). Preferably, an appointment should then be made with a dental professional. The method may be implemented prior to orthodontic treatment.

[0422] Prior to orthodontic treatment, the method can be used, for example, to capture the position and anatomy of the future patient's teeth and begin fabricating intercept or custom orthodontic appliances, such as clear orthodontic aligners, or designing individualized treatment using archwires and brackets.

[0423] The method can be implemented during orthodontic treatment, in particular in order to monitor the process, step a) being carried out less than 3 months, less than 2 months, less than 1 month, less than 1 week, less than 2 days after the start of treatment (i.e. after fitting an appliance designed to correct the positioning of the user's teeth (called an "active retainer")).

[0424] During orthodontic treatment, the method may be implemented to acquire an updated model of the teeth and enable the fabrication of new orthodontic appliances, such as implants, orthodontic braces, or vestibular orthodontic appliances.

[0425] Preferably, the updated model generated in step a) and / or the values ​​determined in step b) are forwarded to a dental professional to assist in establishing a diagnosis.

[0426] The method may also be used after orthodontic treatment to check that the positioning of the teeth has not changed adversely ("relapse"). Step a) is then preferably performed less than 3 months, less than 2 months, less than 1 month, less than a week, less than 2 days after the end of treatment (i.e. after the passive retainer is fitted to hold the teeth in place).

[0427] Size values ​​are preferably used for

[0428] - detect recurrence, and / or

[0429] - determine the rate of change of tooth positioning, and / or

[0430] -Optimize appointment dates with dental professionals, and / or

[0431] - Evaluate the effectiveness of orthodontic treatment, and / or

[0432] - evaluating the evolution of the tooth positioning towards a reference model corresponding to a given tooth positioning (in particular an improved tooth positioning), and / or

[0433] - modifying current orthodontic treatment, for example by manufacturing a new series of orthodontic appliances, and / or

[0434] - in a dental clinic, and / or

[0435] - Visualization and / or measurement and / or detection of dental plaque and / or cavities and / or microcracks and / or wear, for example due to bruxism or the use of active or passive orthodontic appliances, in particular in the case of fractures or separations of orthodontic arches;

[0436] - Visualizing and / or measuring and / or detecting volume changes (e.g., glue deposition on the surface of a tooth), in particular during tooth growth or after intervention by a dental professional;

[0437] -Assess the need for interceptive treatment prior to any orthodontic treatment and, in particular, evaluate the benefits of orthodontic treatment.

[0438] The appearance value is preferably used to detect or assess the location or shape of tooth stains or cavities.

[0439] In a particularly advantageous embodiment, both size values ​​and appearance values ​​are used. Advantageously, the method can thus be used for precise, local monitoring of the evolution of certain pathologies, in particular tooth stains, demineralization or cavities.

[0440] As will now become clear, the present invention provides a method that enables a particular user (e.g., a patient) to generate a model of one or more of their dental arches or one or more of their teeth. The user does not need any special equipment other than a portable scanner that is preferably integrated into the user's mobile phone.

[0441] The acquired model can be acquired without inserting the portable scanner into the user's mouth (i.e., outside the mouth). In particular, processing the updated model to calibrate it allows it to be calibrated to model areas of the mouth that the portable scanner cannot access (e.g., in the interproximal space).

[0442] In one embodiment, in step a), the acquired model is rough. In particular, the acquired model may represent a "3D skeleton" of the user's dental arch with less than 500 points, less than 200 points, less than 100 points, or less than 50 points and / or more than 10 points. Processing the updated model for correction (particularly using a neural network or based on a historical library) may advantageously reconstruct a much more accurate model of the user's dental arch.

[0443] In one embodiment, the portable scanner is partially inserted into the user's mouth. Advantageously, the lingual surface of the teeth can be scanned.

[0444] like Fig.10 As shown, the portable scanner 6 preferably comprises a mobile phone 12, and preferably is transmitted over the air, preferably via Acquisition tool 31 in communication with the mobile phone. Cable communication is also possible.

[0445] The acquisition tool is equipped with an acquisition head 32 that can be inserted into the user's mouth. The acquisition head acquires the acquired model and sends the acquired model to the mobile phone 12, or acquires a signal (e.g., a set of images) and transmits the signal to the mobile phone 12 so that the mobile phone generates the acquired model from the signal.

[0446] Preferably, the acquisition tool has no physical link to the mobile phone, or is connected to the mobile phone by a flexible link such as a cable.

[0447] Preferably, the harvesting tool has a handle 34 to facilitate handling by the user directly or by a bystander, for example in the manner of a toothbrush.

[0448] In one embodiment, the collection tool is attached to the mobile phone, for example by means of a clip, hook and loop fastener, a clamp, a screw, a magnet, a cover or a flexible (preferably elastic) band. Attachment can also be achieved by complementing the shape of the mobile phone. For example, the collection tool can be attached to the phone housing.

[0449] In one embodiment, the method also uses a measuring head in communication with a mobile phone, which is inserted into the user's mouth to collect additional data, such as data on

[0450] -Gap between teeth

[0451] - Lingual surface of teeth

[0452] - Palate, including for example the mid-palatal suture

[0453] -Soft tissue (oral ulcers, benign or malignant lesions, atrophy, etc.)

[0454] - Tooth shades

[0455] - Presence of cavities or stains

[0456] -Condition and / or shape of implants, crowns and / or bridges

[0457] - Status of vestibular or lingual therapeutic appliances (e.g., lingual or vestibular brackets, palatal expanders, or any other therapeutic aids) or retaining devices (palatal arches)

[0458] - Distance between different parts of the same vestibular, lingual or other auxiliary device

[0459] -Condition of the anchoring device (small screws)

[0460] - The distance between the anchor and the instrument in the soft tissue suture opening

[0461] - Postoperative soft tissue healing

[0462] -Spee curve

[0463] -Wilson curve

[0464] - Intercanine distance

[0465] - Intermolar distance

[0466] Fig.11Various images are shown that provide additional data, in particular regarding the palate (including the midpalatal suture) (image 1), soft tissue sutures (image 2), distances between different parts of the same vestibular appliance, tongue or other auxiliary appliance (images 3 and 4), the condition and / or shape of implants, crowns and / or bridges (images 5 and 8), the condition of the anchoring devices (small screws) and the distance between the anchoring devices and the appliance present in the mouth (image 6), the condition of vestibular or lingual treatment appliances (e.g., lingual brackets, vestibular brackets, maxillary breakers or other treatment aids) or retainers (palatal arches) (image 7), interdental spaces and postoperative soft tissue healing (image 9), lingual surfaces of teeth (image 10), intercanine distances and intermolar distances (image 10), tooth shade (image 11), Spee curves (image 12), Wilson curves (image 13), and the presence of cavities or stains (image 14).

[0467] The measuring head may be integrated into a measuring tool having one or more of the features of the acquisition tool. However, unlike the acquisition tool, the measuring tool is not used to acquire the acquired model.

[0468] The acquired model can then be corrected, in particular for finishing and / or cleaning and / or hyper-reality. The user can send the model to a dental professional (whom the user may have never met), who can analyze the model, in particular establish a diagnosis and / or give advice to the user and / or determine an appointment date.

[0469] Of course, the invention is not limited to the embodiments described and shown.

[0470] The method described above for correcting and simplifying the updated model is an invention independent of the described method.

[0471] Further development

[0472] In addition to the method described above and more generally, the present invention also relates to a method for acquiring at least one image of at least one dental arch of a user by means of a mobile phone and an acquisition tool comprising an acquisition head provided with a camera, preferably suitable for insertion into the mouth of a user, wherein the acquisition head:

[0473] - capture the image and send it to a mobile phone, or

[0474] - Acquiring a signal and transmitting it to a mobile phone so that the mobile phone generates an image from the signal autonomously or using a computer in communication with the mobile phone.

[0475] The at least one image is preferably a photograph, preferably a photograph that realistically depicts the dental arch as a person would directly observe it.

[0476] The images can be used to generate the model according to step a), but the image acquisition method according to the invention is no longer limited to this particular embodiment, as the images can be used for other purposes. The method is therefore referred to below as a "generalized method".

[0477] As long as the above-described features of step a) are technically compatible with the generalized method, these features can still be applied to the method.

[0478] The mobile phone and the acquisition tool are preferably operated solely by the user.

[0479] The acquisition can be performed extraorally, without the camera of the acquisition tool being inserted deeply into the user's mouth. The acquisition can be performed intraorally, with the camera of the acquisition tool being inserted deeply into the user's mouth.

[0480] In one embodiment, the collection tool is attached to the mobile phone, for example by means of a clip, hook and loop fastener, a clamp, a screw, a magnet, a cover or a flexible (preferably elastic) band. Attachment can also be achieved by complementing the shape of the mobile phone. For example, the collection tool can be attached to the phone housing.

[0481] However, preferably, the mobile phone and the collection tool communicate with each other, but can move independently of each other. Preferably, there is no rigid device (preferably no mechanism) connecting the mobile phone and the collection tool, so that the mobile phone can move in space (preferably in all spatial dimensions) without having to drag the collection tool with it.

[0482] Preferably, the screen displays the scene observed by the acquisition head camera.

[0483] In particular, the independent movement between the mobile phone and the acquisition tool means that the mobile phone screen can be used to view the scene observed by the acquisition head camera without such viewing being hindered by the operation of the acquisition head.

[0484] In one embodiment, during the acquisition, the user views the mobile phone screen (the mobile phone is preferably stationary relative to the ground (e.g., on a table)) and manipulates the acquisition tool. This makes it easy to position the acquisition tool in the desired position, preferably for extraoral acquisition. In addition, this embodiment allows the user to use the mobile phone camera on the opposite side of the screen without having to use a mirror.

[0485] Preferably, the user captures at least one image seen from the front, preferably at least one image seen from the user's right, even more preferably at least one image seen from the user's left.

[0486] Preferably, the user captures at least one open-mouth image and at least one closed-mouth image.

[0487] The set of acquired images preferably comprises more than two, preferably more than three, preferably more than 5, preferably more than 6 and / or less than 30, preferably less than 20, preferably less than 15, preferably less than 10 acquired images.

[0488] Preferably, the user uses a tool to move their lips apart and better expose the dental arch to the camera of the acquisition tool. The tool can be, for example, a spoon inserted into the mouth.

[0489] In one embodiment, the user uses a retractor, which they partially insert into their mouth.

[0490] Preferably, the generalized method comprises an analysis of said images after said acquisition in order to define the dental condition of the user and preferably to design an active or passive orthodontic treatment plan and / or to check the correct implementation of an ongoing active or passive orthodontic treatment.

[0491] Preferably, the acquisition method involves manufacturing an orthodontic appliance (eg, orthodontic braces) following said image analysis, and preferably shipping said orthodontic appliance to a user.

[0492] The above-described use of images for updating can also be applied to images acquired using the generalized method.

[0493] The at least one image is preferably used for

[0494] - detect recurrence, and / or

[0495] - determine the rate of change of tooth positioning, and / or

[0496] -Optimize appointment dates with dental professionals, and / or

[0497] - Evaluate the effectiveness of orthodontic treatment, and / or

[0498] - evaluating the evolution of the tooth positioning towards a reference model corresponding to a given tooth positioning (in particular an improved tooth positioning), and / or

[0499] - modifying current orthodontic treatment, for example by manufacturing a new series of orthodontic appliances, and / or

[0500] - in a dental clinic, and / or

[0501] - Visualization and / or measurement and / or detection of dental plaque and / or cavities and / or microcracks and / or wear, for example due to bruxism or the use of active or passive orthodontic appliances, in particular in the case of fractures or separations of orthodontic arches;

[0502] - Visualizing and / or measuring and / or detecting volume changes (e.g., glue deposition on the surface of a tooth), in particular during tooth growth or after intervention by a dental professional;

[0503] -Assess the need for interceptive treatment prior to any orthodontic treatment and, in particular, evaluate the benefits of orthodontic treatment.

[0504] Fig.12 An apparatus 6' for implementing this image acquisition method is shown. The kit comprises a mobile phone 12' and a Or WiFi to communicate with the mobile phone acquisition tool 31 '. Cable communication is also possible.

[0505] The acquisition tool 31' is equipped with an acquisition head 32' that can be inserted into the user's mouth. The acquisition head includes a camera 33' that acquires an image and sends it to the mobile phone 12', or acquires a signal and transmits it to the mobile phone 12' so that the mobile phone can generate an image from the signal.

[0506] Preferably, the acquisition tool has no physical link to the mobile phone, or is connected to the mobile phone by a flexible link such as a cable.

[0507] Preferably, the harvesting tool has a handle 34' to facilitate handling by the user directly or by a bystander, for example in the manner of a toothbrush.

[0508] The mobile phone 12' may include one or more of the features of the mobile phone 12. Preferably, the mobile phone is not attached to any support, and in particular not to a support on the user (such as the support 10 described above), and the user can freely manipulate the mobile phone.

Claims

1. A method for acquiring at least one image of at least one dental arch of a user (U) by means of a mobile phone (12') and an acquisition tool (31'), the acquisition tool comprising an acquisition head (32') provided with a camera (33'), wherein the acquisition head: - capturing the image and sending the image to the mobile phone, or - collecting signals and transmitting said signals to said mobile phone so that said mobile phone generates said image from said signals autonomously or using a computer in communication with said mobile phone, The at least one image is a photograph or an image extracted from a video.

2. Method according to the preceding claim, wherein the mobile phone (12') and the acquisition tool (31') are operated exclusively by the user.

3. The method according to any of the preceding claims, wherein the acquisition is performed extraorally, the camera of the acquisition tool not being inserted deep into the mouth of the user.

4. The method according to any one of claims 1 to 2, wherein the acquisition is performed intraorally, the camera of the acquisition tool being inserted deep into the mouth of the user.

5. A method according to any one of the preceding claims, wherein the mobile phone and the acquisition tool are movable independently of each other.

6. A method according to any one of the preceding claims, wherein during acquisition the user views the mobile phone screen to view the scene viewed by the acquisition head camera.

7. Method according to the preceding claim, wherein during acquisition, the mobile phone is stationary relative to the ground and the user operates the acquisition tool.

8. A method according to any of the preceding claims, wherein the user captures at least one image seen from the front, at least one image seen from the right side of the user, at least one image seen from the left side of the user, at least one open-mouth image, and at least one closed-mouth image.

9. The method of any one of the preceding claims, wherein the user uses a tool to move their lips apart and better expose the dental arch to the camera of the acquisition tool.

10. The method according to the preceding claim, wherein the tool is a retractor.

11. A method according to any preceding claim, wherein the acquisition tool communicates with the mobile phone by radio.

12. A method according to any one of the preceding claims, wherein the at least one image is used - determine the rate of change of tooth positioning, and / or -Optimize appointment dates with dental professionals, and / or - assessing the change in tooth positioning towards a reference model corresponding to a given tooth positioning, and / or - Visualization and / or measurement and / or detection of micro cracks and / or wear, and / or - Visualization and / or measurement and / or detection of volume changes during tooth growth or after intervention by a dental professional.

13. A method according to any preceding claim, wherein the image is used to generate a digital three-dimensional model.

Images