METHOD FOR CONTROLLING THE DENTITION

专利摘要:
The invention relates to an acquisition kit comprising - a dental retractor (10) intended to be placed in the mouth of a patient and comprising a registration mark (12); - an image acquisition device comprising - a display screen for an acquireable image, - a computer memory containing information on target acquisition conditions, - a computer program comprising program code instructions for displaying, on said screen, a reference in a position such that, when the registration mark corresponds to the reference on the screen, the acquisition apparatus respects the target acquisition conditions.
公开号:FR3027506A1
申请号:FR1552267
申请日:2015-03-19
公开日:2016-04-29
发明作者:Philippe Salah；William Ayache；Laurent Debraux；Guillaume Ghyselinck；Thomas Pellissard
申请人:H 42；
IPC主号:

专利说明:

[0001] TECHNICAL FIELD The present invention relates to a method for controlling the positioning and / or shape and / or appearance of teeth of a patient and a computer program for carrying out this method. State of the art It is desirable that each regularly check his teeth, in particular to verify that the position and / or shape and / or appearance of his teeth does not evolve unfavorably.
[0002] During orthodontic treatment, this unfavorable development can in particular lead to modifying the treatment. After orthodontic treatment, this unfavorable development, called "recurrence", can lead to a resumption of treatment. Finally, more generally and independently of any treatment, everyone may wish to follow the possible movements and / or the change of shape and / or appearance of his teeth.
[0003] Classically, the controls are carried out by an orthodontist or a dentist who alone have a suitable equipment. These controls are therefore expensive. In addition, visits are binding. An object of the present invention is to respond, at least partially, to the aforementioned problems.
[0004] SUMMARY OF THE INVENTION The invention provides a method for controlling the positioning and / or shape of a patient's teeth, said method comprising the following steps: a) providing a digital three-dimensional reference model of at least a part of an arch, preferably at least one arch of the patient, or "initial reference model" and, preferably, for each tooth, definition, from the initial reference model, of a reference model three-dimensional digital of said tooth, or "tooth model"; b) acquiring at least one two-dimensional image of the patient's arches, called "updated image", under actual acquisition conditions; c) analyzing each updated image and producing, for each updated image, an updated map relating to discriminant information; d) optionally, determining, for each updated image, coarse virtual acquisition conditions approximating said actual acquisition conditions; e) searching, for each updated image, of a final reference model corresponding to the positioning and / or shape of the teeth during the acquisition of the updated image, the search being preferably carried out by means of a method metaheuristic, preferably by simulated annealing, and f) for each tooth model, comparison of the positions of said tooth model in the initial reference model and in the reference model obtained at the end of the preceding steps, referred to as "reference model final ", to determine the displacement of the teeth between steps a) and b), and / or comparison of the shapes of the initial reference model and the reference model obtained at the end of the previous steps, referred to as the" final reference model " In order to determine the deformation and / or movement of teeth between steps a) and b). As will be seen in more detail in the following description, a method of controlling the positioning and / or the shape of the teeth according to the invention allows, from a simple image of the teeth, taken without precise pre-positioning. teeth relative to the image acquisition apparatus, for example a photograph taken by the patient, to accurately assess the displacement and / or the deformation of the teeth since the realization of the initial reference model. This evaluation can also be performed by a simple computer, a server or a mobile phone.
[0005] Preferably, step e) comprises: a first optimization operation making it possible to search for virtual acquisition conditions that best correspond to the actual acquisition conditions in a reference model to be tested determined from the initial reference model, and a second optimization operation making it possible to search, by testing a plurality of said reference models to be tested, the reference model that best corresponds to the positioning and / or shape of the patient's teeth during the acquisition of the patient. updated image in step b).
[0006] Preferably, a first optimization operation is performed for each test of a reference model to be tested during the second optimization operation. Preferably, the first optimization operation and / or the second optimization operation, preferably the first optimization operation and the second optimization operation implement a metaheuristic method, preferably a simulated annealing. Preferably, step e) comprises the following steps: el) definition of a reference model to be tested as the initial reference model, then e2) according to the following steps, testing of virtual acquisition conditions with the model reference number to be tested in order to finely approximate said actual acquisition conditions; e21) determining virtual acquisition conditions to be tested; e22) performing a two-dimensional reference image of the reference model to be tested in said virtual acquisition conditions to be tested; e23) processing the reference image to produce at least one reference map representing, at least partially, said discriminant information; e24) comparing the updated and reference maps so as to determine a value for a first evaluation function, said value for the first evaluation function depending on the differences between said updated and reference maps and corresponding to a decision to continue or stopping the search for virtual acquisition conditions approximating said actual acquisition conditions with more accuracy than said virtual acquisition conditions to be tested determined at the last occurrence of step e21); e25) if said value for the first evaluation function corresponds to a decision to continue said search, modification of the virtual acquisition conditions to be tested, then resumption in step e22); e3) determining a value for a second evaluation function, said value for the second evaluation function depending on the differences between the updated and reference maps in the virtual acquisition conditions approximating at best said actual acquisition conditions and resulting from the last occurrence of step e2), said value for the second evaluation function corresponding to a decision to continue or stop searching for a reference model approximating the shape and / or positioning of the teeth during of acquiring the updated image more accurately than said reference model to be tested used at the last occurrence of step e2), and if said value for the second evaluation function corresponds to a decision to continue said search, modification of the reference model to be tested by deformation of the reference model to be tested and / or by displacement and / or forming one or more patterns of teeth, then resumed in step e2). A method for controlling the positioning and / or the shape of the teeth according to the invention may also comprise one or more of the following optional features: in step a), an occlusion plane is determined according to the following operations: determining the points of the initial reference model which belong to one arcade and which are at a distance from the other arcade which is less than a predetermined distance, preferably at a distance of less than 3 mm from the other arcade, points of contact "; II. optionally, filtering a part of the contact points, preferably so that the number of contact points belonging to the upper arch is identical to the number of contact points belonging to the lower arch, preferably by eliminating the points one arcade furthest from the other arcade; III. linear regression, preferably by the least squares method, on all the remaining contact points so as to determine the occlusion plane; in step a), the following operations are performed: j. projecting, in an occlusion plane, points of contact between the teeth of the upper and lower arches of the patient, the contact points and / or the occlusion plane being preferably determined, according to steps I to III; ii. determining the center of gravity of the projections of said contact points and creating a reference frame, in the occlusion plane, centered on said center of gravity; iii. determining, in said referential, the parabolic function, having the greatest correlation coefficient with all the projections of the contact points; iv. rotation of all the projections of the contact points around the center of gravity, and resumption of the previous operation iii until all the projections of the contact points have traveled a given sector, preferably greater than 90 °, greater than 180 °, even about 360 °; there. identification of the highest correlation coefficient for all the angular positions of all projections of the contact points around the center of gravity, and the axis of the corresponding parabolic function; vi. determining a median longitudinal plane of the initial reference model, said plane passing through said axis and being perpendicular to the occlusion plane; in step a) at least partially delimits a tooth model by following the following operations: determining, at least partially, the gingival edges inside and outside of the arch of the tooth concerned, preferably by analyzing variations in the orientation of the surface of the initial reference model; ii. projection, in the plane of occlusion, of the gingival edges inside and outside; iii. identification of the deformations of the projections of the internal and external gingival margins corresponding to the interdental regions, the vertices of these deformations being called "point of approach" (in an interdental region, the two projections each have a point, the two points pointing substantially one towards the other, the end of a point being a point of approach); iv. determination of the shortest path, on the surface of the initial reference model, between two points of approach of gingival edges inside and outside, respectively, of an interdental region, preferably by a metaheuristic method, preferably by simulated annealing, said more short path at least partially defining a tooth pattern; an updated image is acquired less than 7 days after step a), then steps c) to f) are implemented from this updated image; the time interval between steps a) and b) or between steps A and B may be greater than 1 week, 2 weeks, 1 month, 2 months or 6 months; in step b), an acquisition apparatus carried by hand (and in particular that is not immobilized, for example by means of a support resting on the ground) and / or the patient's head is used. is not immobilized; an individual device chosen from the group consisting of a connected camera, a smart watch, a digital tablet, a portable 3D scanner and a computer coupled with an image acquisition system, such as a webcam or a digital camera, is used. to implement step b) and preferably at least one of the steps, preferably all steps c) to f); in step b), a spacer comprising one, preferably more than two registration marks, preferably non-aligned, and, preferably, the representation of the registration marks on the updated image is used for - to step c), redraw the image and / or - in step d), roughly evaluate the actual acquisition conditions; in step c), the discriminant information is selected from the group consisting of contour information, color information, density information, distance information, gloss information, saturation information, information on reflections and combinations of this information; in step c), the discriminant information is an optimal discriminant information obtained by means of an optimization method according to the invention, described hereinafter; in step d), data provided by the acquisition apparatus and, preferably, concerning its orientation are used; an optimization is carried out by a metaheuristic method, preferably by simulated annealing for: in step a), at least partially determining a gingival edge delimiting a tooth model, and / or in step e2) , search for the virtual acquisition conditions corresponding to the actual acquisition conditions, and / or - in step e), search for a reference model corresponding to the updated image; said metaheuristic method is chosen from the group formed by the evolutionary algorithms, preferably chosen from: evolution strategies, genetic algorithms, differential evolution algorithms, distribution estimation algorithms, artificial immune systems, recomposition Shuffled Complex Evolution pathway, simulated annealing, ant colony algorithms, particle swarm optimization algorithms, taboo research, and the GRASP method; - the kangaroo algorithm, - the Fletcher and Powell method, - the sounding method, - the stochastic tunneling, - the climbing of randomly restarted hills, - the cross-entropy method, and - the hybrid methods between the metaheuristic methods mentioned above; from the comparison in step f), a mapping is produced showing the changes in shape of the initial reference model and / or the displacement of one or more tooth models; the discriminant information used for the updated map and / or for the reference map is, prior to this use, optimized by means of an optimization method according to the invention described hereinafter, comprising steps C1 to C3 ., the acquired image being the updated image or the reference image, respectively, and the reference model being the initial reference model or the reference model to be tested, respectively. The invention also relates to the use of a method for controlling the positioning of teeth according to the invention for - detecting a recurrence, and / or - determining a speed of evolution of a change of positioning of the teeth, and / or - optimize the date of appointment with an orthodontist or dentist, and / or - assess the effectiveness of orthodontic treatment, and / or - evaluate the evolution of the positioning of teeth to a theoretical model corresponding to a determined positioning of the teeth, in particular improved positioning of the teeth, and / or - in dentistry.
[0007] The method may especially be used during orthodontic treatment, in particular to control the progress, step a) being carried out less than 3 months, less than 2 months, less than 1 month, less than a week, less than 2 days after the beginning of the treatment, that is to say after the installation of an apparatus intended to correct the positioning of the teeth of the patient, said "apparatus of active contention".
[0008] The method can also be implemented after orthodontic treatment, to check that the positioning of the teeth does not evolve unfavorably ("recurrence"). Step a) is then preferably carried out less than 3 months, less than 2 months, less than 1 month, less than 1 week, less than 2 days after the end of the treatment, that is to say after the installation of a device to keep the teeth in position, called "passive restraint apparatus". In one embodiment, to control the movement of the teeth exclusively, it is considered that the tooth models are indeformable during step e). In particular, in step e3), the reference model to be tested can only be modified by moving one or more tooth models.
[0009] The invention also relates to the use of a method of controlling the form of teeth according to the invention for: - visualizing and / or measuring and / or detecting a dental plaque, and / or a beginning of caries, and / or microcracking, and / or wear, for example resulting from bruxism or the implementation of an orthodontic appliance, active or passive, especially in case of rupture or detachment of an orthodontic arch; visualizing and / or measuring and / or detecting a change in volume, in particular during the growth of the teeth or following an intervention by a dentist or an orthodontist, for example a deposit of glue on the surface of the teeth; - to evaluate the desirability of an interceptive treatment, before any orthodontic treatment, in particular to evaluate the interest of an orthodontic treatment.
[0010] In one embodiment, to control exclusively the deformation of the teeth, it is considered, during step e), that the tooth models are fixed, that is to say have not moved between the steps a) and B). In particular, in step e3), the reference model to be tested can only be modified by deformation of one or more tooth models. The comparison of the shapes of the initial reference model and the final reference model in order to determine the deformation of teeth between steps a) and b) can result in particular from a comparison of the shape of one or more tooth models in the initial reference model and in the final reference model. The invention further relates to a method for controlling a tooth appearance property of a patient, said method comprising the following successive steps: A. acquisition, by means of a first acquisition apparatus, of at least a first two-dimensional image of said teeth and a first reference gauge, called "initial image"; B. acquisition, by means of a second acquisition device, of at least a second two-dimensional image of said teeth and of a second reference gauge having the same appearance as the first reference gauge, called "updated image"; C. initial and updated image normalization so that the representations of the first and second reference gages on the initial and updated normalized images have the same appearance; D. before or after step C., locating the same region of the teeth on the initial and updated images; E. comparison of the appearance of said region on the standardized initial and updated images. A method of controlling a tooth appearance property according to the invention preferably comprises one or more of the following optional features: the time interval between steps A. and B. is greater than 1 week; the first acquisition apparatus and / or the second acquisition apparatus are cameras and / or mobile telephones; the acquisitions at steps A. and / or B. are performed under the illumination of a flash; the reference gauges used for each of the steps A. and B. have the same aspect; the reference gauges used for each of steps A. and B. are attached to a dental retractor; the acquisitions in steps A. and / or B. are carried out by means of an acquisition kit according to the invention, described below; the reference gauges used for each of steps A. and B. are locator marks; the first acquisition apparatus and / or the second acquisition apparatus comprises a computer program comprising program code instructions for locating, in real time, the locator mark (s) on the retractor, analyzing its or their positions and / or dimensions, in particular the relative positions of several registration marks and, therefore, provide information, preferably light or sound, so as to inform the user of said acquisition apparatus; in step D, the identification comprises a comparison of discriminant information common to both initial and updated images, and then an identification of the position of said region with respect to said common discriminant information; in step D, the identification of the region on the initial and / or updated images comprises a search for virtual acquisition conditions in which the first and / or second acquisition apparatus, respectively, would have acquired said initial image and / or updated, respectively, by observing a digital three-dimensional reference model of the patient's arches. in step D, the identification of the region on the initial and / or updated images comprises the implementation of a method for evaluating the actual acquisition conditions according to the invention, described below.
[0011] The invention also relates to an acquisition kit, in particular for the implementation of a step b), A or B, said acquisition kit comprising: a dental retractor intended to be placed in the mouth of a patient and having a registration mark; an image acquisition apparatus comprising; - a display screen, - a computer memory containing information on target acquisition conditions, - a computer program comprising program code instructions for simultaneously displaying, on said screen, an acquirable image and a reference, said reference being in a position such that, when the registration mark corresponds to the reference on the screen, the acquisition apparatus complies with the target acquisition conditions. An acquisition kit according to the invention can in particular be implemented in step b) of a method for controlling the positioning and / or shape of the teeth according to the invention, or in steps A and / or B. a method for controlling a property of appearance of teeth, and more generally for any method comprising an evaluation of the acquisition conditions of an image. As will be seen in more detail in the following description, an acquisition kit according to the invention allows in particular to position the acquisition apparatus in a position that substantially corresponds to a predetermined position, for example considered optimal for the desired control. An acquisition kit according to the invention therefore makes it possible to considerably improve the speed of information processing for the implementation of the control methods according to the invention. An acquisition kit according to the invention preferably has one or more of the following optional features: the acquisition apparatus is a mobile telephone; the reference is chosen from the group consisting of - a point, - a geometric shape, preferably a circle, a square, a rectangle or a line, - a colored zone of the same color as the said registration mark, - a shape identical to the shape of said registration mark, - a shape complementary to the shape of said registration mark, in particular to constitute a form having a meaning, such as a geometric shape, a letter or a text, a drawing, or a motif , and their combinations; the spacer comprises several non-aligned and preferably coplanar registration marks; - The registration mark is arranged so that when it corresponds to said reference on the screen, it is less than 1 cm from one edge of the screen. The invention also relates to a method for acquiring a two-dimensional image of a portion of a dental arch, or a dental arch or two dental arches of a patient using an acquisition kit according to the invention, in particular for the implementation of a step b), A. and / or B. This process is remarkable in that it comprises the following successive steps: (a) determination of target acquisition conditions for example depending on a treatment to be applied, in particular orthodontic treatment, and determination of match conditions adapted to match a locator mark of the spacer with a reference displayed on the screen of the acquisition device results in the application of target acquisition conditions; (b) programming the acquisition apparatus to display the reference in a position such that said mapping results in application of the target acquisition conditions; (c) placing the retractor in the patient's mouth; (d) positioning the acquisition apparatus so as to match the registration mark and the reference and thereby apply the target acquisition conditions; (e) acquiring the image that can be acquired in the positioning of the acquisition apparatus adopted in the previous step. The target acquisition conditions are the conditions allowing a suitable positioning of the acquisition apparatus, preferably an optimal positioning of the acquisition apparatus for acquiring the image. Preferably, the target acquisition conditions are therefore determined according to the teeth to be observed. Preferably, an acquisition method according to the invention is implemented for the steps of the control methods according to the invention requiring the acquisition of a two-dimensional image of a portion of an arch or a dental arch or of the two dental arches of a patient, in particular for steps b). Preferably, the cycle of steps (a) to (e) is repeated several times, preferably more than twice or even more than three times, with different target acquisition conditions. For example, to measure the displacement of a tooth, first target acquisition conditions may correspond to a position 40 cm from the spacer, opposite and at the height of the spacer. Second and third target acquisition conditions may correspond to a positioning at 40 cm from the spacer, at the height of the spacer, at 450 to the right and to the left of the sagital plane, respectively. The invention also relates to a method of optimizing a discriminant information extracted from a two-dimensional image of the dental arches of a patient, called "acquired image", by means of a three-dimensional numerical reference model of at least one part of an arch of the patient, or an arch or two arches of the patient said method comprising the following steps: C1. evaluation of the quality of the discriminant information and a quality threshold, filtering so as not to retain only discriminant information of a quality above the quality threshold, and definition of "discriminant information to be tested" as the discriminant information retained; C2. testing a concordance between the discriminant information to be tested and said reference model; C3. evaluation of the test result, and according to said evaluation: - addition of discriminant information not retained to the discriminant information to be tested and / or deletion of discriminant information in the discriminant information to be tested, then resumed at step C2. or, - definition of the optimal discriminant information as the discriminant information to be tested. Preferably, an optimization method according to the invention also comprises one or more of the following optional features: the discriminant information is selected from the group consisting of contour information, color information, density information, distance information, gloss information, saturation information, glare information, and combinations of such information; step C2. comprises the following steps: - search for virtual acquisition conditions approximating, preferably optimally, the actual acquisition conditions in which said acquired image has been acquired and observation of the reference model in said conditions of virtual acquisitions so to obtain a reference image; processing the acquired image and the reference image to produce at least one acquired map and a reference map, respectively, said acquired and reference maps representing said discriminant information; comparison of the acquired and reference maps so as to determine a degree of concordance, the result of the test of step C2. dependent, preferably being equal to said degree of concordance; the search for virtual acquisition conditions approximating real acquisition conditions comprises the following steps: 01) optionally, determination of coarse virtual acquisition conditions approximating said actual acquisition conditions, preferably by analysis of the representation, on the basis of acquired image, of a retractor used during the acquisition of the acquired image; 02) determination of virtual acquisition conditions to be tested; 03) performing a two-dimensional reference image of the reference model observed in the virtual acquisition conditions to be tested; 4) processing the reference image to make at least one reference map representing said discriminant information; 5) comparison of the acquired and reference cards so as to determine a value for an evaluation function, said value for the evaluation function depending on the differences between said acquired and reference cards and corresponding to a decision to continue or to stop the search for virtual acquisition conditions approximating the actual acquisition conditions with more accuracy than said virtual acquisition conditions to be tested; if said value for the evaluation function corresponds to a decision to continue said search, modification of said virtual acquisition conditions to be tested, then resumption at step 03); otherwise, evaluation of the actual acquisition conditions by said virtual acquisition conditions to be tested; determining the discriminant information to be added and / or added in step C3. results from the implementation of a metaheuristic method. The invention also relates to a method for evaluating the actual acquisition conditions of a two-dimensional image of the teeth of a patient, called "acquired image", said method comprising the following steps: 001) realization of a reference model three-dimensional digital at least a portion of an arch, preferably an arch, preferably the two arches of the patient; 002) analysis of the acquired image and creation of a map relating to discriminant information, called "acquired map"; 003) searches for virtual acquisition conditions approximating said actual acquisition conditions, preferably according to steps 01) to 05). One or more optional features of step a) are applicable in step 001). In particular, the reference model can be prepared, by a scan, from measurements made on the teeth of the patient or on a physical model of his teeth, for example a plaster model. One or more optionally optional features of step c) are applicable at step 002).
[0012] The invention also relates to: - a computer program, and in particular a specialized application for a mobile telephone, comprising program code instructions for the execution of one or more, preferably all the steps b) to f) or A. to E. or C1 to C3, when said program is executed by a computer, - a computer medium on which is recorded such a program, for example a memory or a CD-ROM, and - a personal apparatus, in particular a mobile phone or tablet, in which such a program is loaded. The invention also relates to a system comprising a three-dimensional scanner capable of implementing step a) of a method for controlling the positioning and / or the shape of the teeth according to the invention, or a step 001). a personal apparatus, preferably a mobile telephone, loaded with a program according to the invention. Definitions "Patient" means any person for whom a procedure is used to control the teeth, whether or not the person is ill, or whether the person is being treated or not. "Dental professional" means a dentist, orthodontist or orthodontic laboratory. "Dentist" means a dentist or a dental assistant working under the responsibility of a dentist.
[0013] By "dentition" is meant the two dental arches of the patient. An image of an arcade is of course a partial representation of this arcade. A "mobile phone" is a device of less than 500 g, equipped with a sensor to capture images, able to exchange data with another device more than 500 km away from the mobile phone, and capable of display said data, and in particular said images.
[0014] For a method of controlling the positioning of the teeth, the "acquisition conditions" specify the position and orientation in the space of an image acquisition apparatus relative to the patient's teeth or to a tooth model of the patient. patient. The "occlusal plane" is the plane that provides the best linear correlation with all the points of contact between the teeth of the upper arch on the one hand and the teeth of the lower arch on the other hand. The "median longitudinal plane" is the substantially vertical plane when the patient holds the right head, which separates in a substantially symmetrical manner from the right and left parts of each arch.
[0015] A "tablet" is a touch screen laptop. A 3D scanner is a device for obtaining a three-dimensional representation of an object. By "image" is meant a two-dimensional image, like a photograph. An "acquirable" image is the image that the acquisition device can record at a given moment. For a camera or phone, it is the image that appears on the screen when the photo or video acquisition application is running. "Comprising a" or "having a" or "having a" means "having at least one", unless otherwise indicated. In the various methods described, the references of the steps are identical if these steps are similar or identical. BRIEF DESCRIPTION OF THE FIGURES Other features and advantages of the invention will become apparent on reading the following detailed description and on examining the appended drawing in which: FIG. 1 represents a logic diagram illustrating the implementation of FIG. a method for controlling the positioning and / or shape of teeth according to the invention; FIG. 2 represents an example of an initial reference model; FIG. 3 illustrates the treatment performed to determine the occlusion plane; FIG. 4 (4a-4d) illustrates the step necessary to determine the tooth models in a reference model, - FIG. 5 (5a-5d) illustrates the acquisition of updated images, as well as the cutting operation. Fig. 6 (6a-6b) illustrates the processing of an updated image for determining the contour of the teeth; Fig. 7 schematically illustrates the relative position of registration marks 12 on updated images 141 and 14; 2 of a spacer 10, according to the observation direction (broken line), - Figure 8 shows a map resulting from the implementation of a method for controlling the shape of teeth of a patient according to the invention FIG. 9 represents a logic diagram illustrating the implementation of a method for controlling the appearance of teeth according to the invention; FIG. 10 represents a logic diagram illustrating the implementation of an optimization method; discriminating information according to the invention, and - Figure 11 shows, on an acquired image, a reference map established for a reflection information. Detailed Description of a Method for Controlling the Position of Teeth A method for controlling the positioning of teeth according to the invention comprises the steps mentioned above. In step a), an initial reference model of the arches, or part of the arches of the patient is created (see Figure 2). The initial reference model is a three-dimensional digital model of the patient's arches, for example of the .stl or .Obj, .DXF 3D, IGES, STEP, VDA, or Point Cloud type. Advantageously, such a model, called "3D", can be observed at any angle.
[0016] For monitoring orthodontic treatment, the initial reference model is preferably prepared at the beginning of the treatment. The initial reference model may correspond to a positioning of the patient's teeth before the treatment or a positioning of the patient's teeth that the treatment proposes to achieve. In this case, the initial reference model is classically calculated from a first three-dimensional model corresponding to the positioning of the patient's teeth before the treatment.
[0017] For the control of the recurrence, the initial reference model is preferably prepared less than six months, preferably less than three months, more preferably less than one month after the end of the orthodontic treatment, generally immediately after the end of the treatment. . It thus corresponds to a substantially optimal positioning of the teeth.
[0018] The initial reference model can also be prepared independently of any treatment, for example because the patient wishes to monitor the movements of his teeth. The initial reference model can be prepared from measurements made on the patient's teeth or on a physical model of his teeth, for example a plaster model.
[0019] The initial reference model is preferably created by means of a professional apparatus, for example by means of a 3D scanner, preferably implemented by a health professional, for example by an orthodontist or an orthodontic laboratory . In an orthodontic cabinet, the patient or the physical model of his teeth can be advantageously arranged in a precise position and the professional apparatus can be perfected. The result is a very precise initial reference model. The initial reference model preferably provides information on the positioning of the teeth with an error of less than 5/10 mm, preferably less than 3/10 mm, preferably less than 1/10 mm. Orientation of the Initial Reference Model: Preferably, the orientation of the initial reference model in space is determined, and preferably, preferably, the occlusion plane and the median longitudinal plane. The occlusal plane and the median longitudinal plane can be determined manually, approximately. The inventors, however, have discovered methods for determining these plans by computer processing.
[0020] Preferably, the reference model is a model of the closed mouth arches, that is to say in a position in which teeth of the upper arch are in contact with teeth of the lower arch. Conventionally, the initial reference model provided by a three-dimensional scanner makes it possible to distinguish the upper arch from the lower arch. Generally, the model is provided in the form of two files respectively corresponding to these arcades, and comprising data for positioning the models of these arcades relative to each other in the occlusion position. Preferably, to estimate the points of contact between the teeth of the upper and lower arches, all the points of the model of the upper and lower arches which are at a distance less than a predetermined limit are determined. the limit is preferably less than 3 mm, preferably about 2 mm. All other points of these models are then ignored, which leads to the representation of Figure 3b. A linear regression then makes it possible to determine the occlusion plane ("plane 1" in FIG. 3c).
[0021] The initial reference model can thus be oriented along the occlusal plane (Fig. 3d). If the initial reference model does not have data for positioning the upper and lower arches relative to each other, an occlusion bite is preferably used, showing the points of contact between the upper teeth and the teeth. lower teeth, then reposition the models of the upper and lower arches in relation to this bit of occlusion. The median longitudinal plane is perpendicular to the occlusal plane, but its orientation is not known. Preferably, one proceeds in the following manner to determine the orientation of the median longitudinal plane: One considers axes [Ox) and [Oy) in the plane of occlusion, the point 0 being the barycentre of the normal projections of the points of contact on the occlusal plane. - In this reference (x0y), we search the curve, preferably parabolic, with the greatest correlation coefficient with all of said projections. - The set of projections of the contact points is then moved in the occlusion plane, by rotation around the point 0, and we repeat the previous step from this new angular position projections of the contact points. The cycle of the previous operations is continued, preferably until all the points of contact of 360 ° have been rotated around the centroid O. The correlation coefficients corresponding to the different orientations of the set of contact points are then compared. . The axis of the curve that leads to the highest correlation coefficient is then considered as included in the median longitudinal plane, which allows to define exactly the orientation of the latter. The orientation in the space of the initial reference model is thus perfectly determined, in a fast manner.
[0022] Creating tooth models In the initial reference model, a part that corresponds to a tooth, or "tooth model", is delimited by a gingival margin that can be decomposed into an interior gingival margin (on the inside side of the tooth). the mouth to the tooth), an external gingival margin (facing out of the mouth with respect to the tooth) and two lateral gingival margins. The gingival edges correspond to regions in which the orientation of the surface defined by the initial reference model undergoes changes of high amplitude. These variations of orientation can be identified according to known techniques, for example by identifying the changes of direction of the normal to the modeled surface. Figure 4a shows a view of the initial reference model processed to reveal these changes of direction. Figure 4b shows the internal gingival margin that can be extracted by analyzing the image of Figure 4a. Several views of the initial reference model are thus analyzed, which makes it possible to determine the internal and external gingival edges in three dimensions, as represented in FIG. 4c.
[0023] Moreover, in projection in the plane of occlusion, the gingival contours inside and outside of an archway are approaching on both sides of a tooth. To determine a lateral gingival margin of a tooth, the shortest path, on the surface of the initial reference model, is sought between the two points of the inner and outer gingival margins so close together and substantially facing each other. The search for the shortest path between two points on a three-dimensional model uses well-known optimization techniques. Preferably, this search results from a metaheuristic method, preferably a simulated annealing. Two adjacent lateral gingival margins and the inner and outer gingival border portions that connect these lateral gingival edges thus allow the delineation of a tooth at the gingiva. Taking into account that a tooth extends from the gingival contour to the occlusal plane, it is possible to determine the parts of the initial reference model that correspond to the different teeth ("tooth models"). Figure 4d shows the set of tooth models of an arch. The initial reference model can be stored in a centralized database, grouping the initial reference models of a plurality of patients. This database can be physically installed in a specialized institution. It can also be installed in a laboratory or orthodontic practice, which limits the transfer of confidential information. In one embodiment, the initial reference model is delivered to the patient. Preferably, a computer file corresponding to the initial reference model is recorded on a removable medium, for example on a USB key or on an electronic card, preferably on a mobile phone, a tablet or a laptop of the patient, and in particular on the personal apparatus which will preferably be used in steps b) and following. Preferably, the patient or dental professional loads the initial reference model into said individual device or makes it available for loading into said individual device. The patient preferably loads the initial reference model from the internet. In a preferred embodiment, the reference model is not delivered to the patient. Preferably, the reference model is only made available to a specialized institution to implement steps c) to f). It can remain stored in the establishment in which it was performed in step a) and where, preferably, steps c) to f) are implemented. In step b), an updated image of part of an arcade, arcade or arcades is taken by means of an image acquisition apparatus. Step b) is preferably performed by the patient or a close relative of the patient, but can be performed by a dentist.
[0024] Time of Acquisition Preferably, the updated image is taken after a time interval Δt after step a). The time interval At can be predetermined. It can be constant, whatever the occurrence of the process, that is to say that this interval concerns the first execution of the process or a subsequent execution. It can be variable, and depend for example on the results obtained following an earlier execution of the process. In particular, for the control of the recurrence, the interval of time At can be even shorter than this execution made it possible to detect a large drift.
[0025] In a preferred embodiment, the interval of time At is determined by the orthodontist, according to a schedule of the controls. According to the evolution of the position of the teeth, the orthodontist can modify this schedule and modify accordingly the time interval At. In one embodiment, the method of controlling the positioning of teeth according to the invention is executed. several times, the time intervals between each execution being identical or different. The time intervals between two successive executions can all be determined before the first execution to correspond to a control schedule developed by the orthodontist. The time interval Δt can also be indeterminate and depend for example on the patient's decisions. For example, creating an updated image can be done at a dentist appointment or at any time when the patient wishes, or even independently of any orthodontic treatment. The time interval Δt is preferably determined to correspond to a potentially significant evolution of the positioning of the teeth.
[0026] For example, for the control of recurrence, the time interval Δt is preferably less than three months in the first year after treatment. After this first year, the time interval Δt is preferably greater than one month, or even greater than six months or more than twelve months. In particular for the detection of tooth drift, a time interval of between six months and eighteen months is adapted.
[0027] Preferably, at least one reminder informing the patient of the need to create an updated image is sent to the patient. This reminder can be in paper form or, preferably, in electronic form, for example in the form of an email, an automatic alert of the mobile specialized application or SMS. Such a reminder may be sent by the office or the orthodontic laboratory or by the dentist or by the mobile specialized application of the patient, for example. In a preferred embodiment, a refreshed image is acquired before the teeth have been able to move significantly, substantially at the same time as the creation of the initial reference model, preferably less than 7 days, less than 3 days, less 1 day after step a), that is to say before the teeth could move significantly. The implementation of the method with this updated image advantageously makes it possible to verify that the method does not lead to the detection of any difference between the initial and final reference models, and therefore functions correctly.
[0028] In one embodiment, the updated image may be acquired prior to the creation of the initial reference model. For example, steps a) and b) can be performed at the end and at the beginning of orthodontic treatment, respectively. In particular, it is possible to evaluate the effectiveness of the treatment in the absence of a 3D model at the beginning of treatment.
[0029] The interval of time At 'separating steps a) and b) in this embodiment can in particular take the values described above for At. Apparatus for acquiring images Preferably, the acquisition apparatus of images is a personal device currently commercially available, for example a mobile phone, a camera said "connected", a watch called "smart" or "smartwatch", or a tablet or a personal computer, fixed or portable, comprising an image acquisition system, such as a webcam or a camera, preferably a digital camera. Even if the updated image can in particular be created by a dentist, it is preferably created by the patient himself or by one of his relatives.
[0030] The image acquisition apparatus preferably weighs less than 3 kg, less than 2 kg, less than 1 kg, less than 500 g, preferably less than 300 g. Step b) can therefore advantageously be carried out at a distance from step a), that is to say in a place different from that in which step a) is carried out, in particular more than 50 m, more than 100 m, more than 1 km from the place where is carried out step a), in particular outside orthodontic practice. In one embodiment, step b) is not performed in a dental office, an orthodontic practice or an orthodontic laboratory, except, possibly, during a session intended to train the patient. Preferably, the updated image is a photograph, in particular a panoramic photograph. In one embodiment, the updated image is extracted from a film.
[0031] In a preferred embodiment, the method uses several updated images to have at least one representation of each tooth, preferably at least three updated images corresponding to a front view, a right view and a left view of the teeth. of the patient. Preferably, in step b), at least one updated image is taken at the closed mouth position and at least one refreshed image is in the open mouth position. The closed mouth image advantageously makes it possible to identify the relative displacements between the two arches. The updated open mouth image advantageously makes it possible to identify the contours of the teeth, without the teeth of the upper arch obscuring the teeth of the lower arch or vice versa. Up-to-date images can be taken either for the upper arch, or for the lower arch, or, preferably, for the two archways, in whole or in part. Several similar images (representing substantially the same teeth) can also be useful in order to search for the best score. Depending on the acquisition conditions, discriminant information may in particular lead to different scores depending on the updated image used.
[0032] Preferably, a dental spacer is used in step b), as shown in FIGS. 5a and Sc. The first function of the spacer is to move the lips apart in order to improve the visibility of the teeth. Preferably, a retractor is given to the patient, for example during an appointment with his orthodontist or his dentist. The image acquisition apparatus preferably provides color images, and / or infrared images of the patient's mouth, or even the patient's face. The infrared images advantageously make it possible to make the teeth appear with an excellent contrast. Preferably, the image acquisition apparatus comprises a specialized application making it possible to implement step b), but also, preferably, following steps, preferably all of the following steps. More preferably, this application manages reminders and informs the patient of the need to create an updated image. Preferably, the specialized application is loaded into the image acquisition apparatus from a physical medium such as a USB key or a CD-ROM, or is downloaded over the internet or over the air. In one embodiment, the specialized application is provided to the patient by the office and / or the orthodontic laboratory. It can in particular take the form of an application of the type commonly downloaded on iPhones brand Applee or devices of any brand implementing Androide operating systems or any other operating system. The image acquisition apparatus preferably comprises a camera or a video or infrared camera, which the user, for example the patient or a relative, positions by means of a viewfinder or a screen, before activating it.
[0033] Means Controllers and Acquisition Kit A method of controlling the positioning of teeth according to the invention does not require a precise positioning of the image acquisition apparatus with respect to the teeth. In one embodiment, no positioning constraints to provide an arrangement of the image acquisition apparatus less than 30 cm, less than 20 cm, 10 cm or less than 5 cm from a given location is not imposed. Preferably, the image acquisition apparatus, however, comprises polarizing means facilitating its approximate positioning relative to the patient before acquiring the updated image.
[0034] The user can be guided by written and / or voice messages for the acquisition. For example, the personal device may announce "take a picture from the front", send a signal to inform the user that the photo is acceptable or that on the contrary, he must redo a photo, announce "take a picture on the right" preferably by displaying an arrow to orient the user, etc. The end of the acquisition process can also be announced by the device. The apparatus can also assist in positioning, for example by visual (eg, arrows), and / or audible (such as a succession of beeps which increase in frequency as the positioning of the apparatus improves. ), and / or written and / or vocal ("higher", lower ", etc.). The polarizing means may in particular comprise marking marks that appear on the viewfinder or the screen. The registration marks may for example comprise a line intended to be aligned with the general direction of the joint between the upper teeth and the lower teeth when the teeth are clamped by the patient, or a vertical line intended to be aligned with the joint between the two upper incisors. The registration marks may also refer to other parts of the patient. For example, they may consist of marks corresponding to the position of the eyes or take the form of an outline in which must be positioned the patient's mouth or face. In a preferred embodiment, the registration marks correspond to a reference system, for example on the retractor. A repository can also be worn by a piece bitten by the patient.
[0035] In a preferred embodiment, the acquisition is performed by means of an acquisition kit according to the invention comprising: a dental retractor, preferably made of a biocompatible material, comprising a registration mark; an image acquisition apparatus, preferably of the type described above, comprising an image display screen that can be acquired, and a computer program comprising program code instructions for displaying a reference on said screen said reference preferably being stationary on the screen, and arranged in a position in which, when the registration mark corresponds to the reference on the screen, the acquirable image represents the retractor under an angle of view and / or at a predetermined distance (e) (s). The reference is "still" on the screen when it is not moving on the screen when the acquisition device is moving. The acquisition device can be in particular a mobile phone and the program can be a specialized application for mobile phone. The spacer may have the characteristics of the spacers used so far. It conventionally comprises a support provided with a flange extending around an opening and arranged so that the lips of the patient can rest there by letting the patient's teeth appear through said opening (Figure 5a and Figure Sc).
[0036] The support, for example plastic, preferably has a substantially flat shape and a weight of less than 500 g, preferably less than 300 g. The opening is preferably arranged substantially in the center of the support. The surface of the opening is preferably greater than 15 cm 2, greater than 30 cm 2, greater than 40 cm 2, greater than 50 cm 2, and / or less than 100 cm 2, less than 80 cm 2, smaller than 60 cm 2.
[0037] The "match" of a reference and a registration mark is a predefined disposition of the latter. It indicates a particular positioning of the acquisition apparatus with respect to the retractor. The correspondence depends on the nature of the reference and the registration mark. The predefined situation, which corresponds to target acquisition conditions, may especially be an overlay, total or partial, a juxtaposition, or an alignment of the reference and the registration mark. The exact superimposition of the reference and the registration mark makes it possible not only to determine the direction towards which the objective of the acquisition apparatus is to point and / or the distance between the acquisition apparatus and the retractor, but also, if the reference is asymmetrical, the orientation of the acquisition apparatus around this direction. The dimensions and / or surfaces of a registration mark and the corresponding reference and / or the distance between several registration marks and between corresponding references may be used to adjust the distance between the acquisition device and the retractor. The reference may be for example - a fixed line, on which the user must for example align registration marks, - a shape, preferably asymmetrical, corresponding to the shape of a registration mark to be superimposed, for example a point that the user must for example superimpose the registration mark, or a circle in which the user must for example place the registration mark, - a colored form corresponding to the color of a registration mark to be superimposed, - a complementary shape to the shape of a registration mark, preferably so that the matching of the registration mark and the reference leads to a shape having a meaning, such as a geometric shape, a letter or a text, a drawing, or a pattern, for example.
[0038] Preferably, the registration mark has an area greater than 2 mm 2, preferably greater than 5 mm 2, preferably greater than 10 mm 2, even greater than 20 mm 2, even greater than 30 mm 2, and / or less than 50 mm 2. A large registration mark also improves the positioning accuracy of the acquisition device.
[0039] Preferably, as shown in Figure 5a, the spacer has a plurality of registration marks, preferably non-aligned, preferably coplanar. The registration marks may be identical or different. The registration marks may in particular be different according to their position, for example according to whether they are in the upper part or in the lower part of the spacer, or to the right or left of the spacer.
[0040] The registration mark may be the same or different from the corresponding reference. It is preferably of geometric shape, for example a point, one or more lines, for example parallel, a star, a circle, an oval, a regular polygon, in particular a square, a rectangle or a rhombus.
[0041] The registration mark may also be an image, a letter, a number or a sequence of letters and / or numbers. The registration mark is preferably of a different color from the surface of the spacer which surrounds it, preferably so as to offer a high contrast. A registration mark may be visible or invisible to the naked eye, as long as it appears on the screen of the acquisition device. To improve the accuracy, the registration marks are preferably spaced from each other so that, when they correspond to their respective references on the screen, at least first and second registration marks are less than 3 cm, preferably less than 2 cm, preferably less than 1 cm, preferably less than 0.5 cm, first and second edges, respectively, of the screen. The first and second edges are preferably opposite edges of the screen. The registration mark may have one or more dimensions and / or a shape and / or a color identical to or different from that of the corresponding reference. In a preferred embodiment, the polarizing means are defined, at least partially, from information provided by the initial reference model. For example, following the principles of "augmented reality", a view of the initial reference model, for example a front view or a right view or a left view of the initial reference model, can be made visible, in transparency. , on the screen of the image acquisition device during acquisition. It is thus very easy for the patient to superimpose approximately such a view with the teeth that he must take pictures of. The steps c) and following are preferably performed either on a personal device of the patient, preferably with the device used in step b), or with an application at a dental professional, or with a dedicated third party server. In step c), each updated image is analyzed so as to produce, for each updated image, an updated map relating to at least one discriminant information.
[0042] Redrawing The image analysis may include a redrawing of the updated image to isolate the relevant part, in particular to remove, at least partially, from the updated image the elements that have not been the subject the initial reference model, such as the patient's nose or eyes, or the retractor. This redistribution or "croppage" is facilitated by the representation of registration marks on the updated image. In particular, preferably, as shown in Figures 5a and 5c, the spacer 10 carries at least three non-aligned registration marks 12. If the spacer is in several parts, for example conventionally in two parts, each part preferably carries at least three non-aligned registration marks. The shape of a registration mark, for example an asymmetrical shape, can also be used to identify the position of the spacer on the updated image. Preferably, the registration marks have shapes and / or colors facilitating their identification on a refreshed image. For example, they may be black while the rest of the spacer is white. In one embodiment, the registration marks have shapes and / or colors that make it possible to identify them individually. For example, they may each be of a different color. The identification of the registration marks on the updated image makes it possible to identify the zone of the updated image containing the elements that were the subject of the initial reference model, that is to say the teeth and the gums. The updated image can then be cropped accordingly. The comparison of Figures 5a and 51), or Sc and 5d, illustrates the effect of redrawing on a refreshed image. Updated map An updated map represents discriminant information in the repository of the updated image. For example, Figure 6b is an updated tooth contour map obtained from the updated image of Figure 6a. The discriminant information is preferably selected from the group consisting of contour information, color information, density information, distance information, gloss information, saturation information, glare information, and color information. combinations of this information.
[0043] Those skilled in the art know how to process an updated image to reveal the discriminating information. This treatment comprises for example the application of masks or well-known filters, provided with image processing software. Such treatments make it possible, for example, to detect regions of high contrast in order to determine contours. These treatments include in particular one or more of the following known and preferred methods, namely: by application of a Canny filter, especially for searching contours using the Canny algorithm; - by application of a Sobel filter, in particular to calculate derivatives by means of the extended operator of Sobel; - by applying a Laplace filter, to calculate the Laplacian of an image; - by detection tasks on an image ("Blobdetecor"); - by applying a threshold ("Threshold") to apply a fixed threshold to each element of a vector; - by resizing, using relations between the zones of pixels ("Resize (Area)") or bi-cubic interpolations on the environment of the pixels; by erosion of the image by means of a specific structuring element; by dilation, of the image by means of a specific structuring element; by retouching, in particular by using regions in the vicinity of the restored zone; - by applying a bilateral filter; - by application of a Gaussian blur; - by applying an Otsu filter, to find the threshold that minimizes intra-class variance; - by applying a filter A *, to search for a path between points; - by applying an adaptive threshold (Adaptive Threshold) to apply an adaptive threshold to a vector; by applying a filter for equalizing a histogram of a grayscale image in particular; - by blur detection ("BlurDetection"), to calculate the entropy of an image using its Laplacian; by edge detection ("FindContour") of a binary image; by color filling ("FloodFill"), in particular to fill a connected element with a specific color. The following nonlimiting methods, although not preferred, may also be implemented: by applying a "MeanShift" filter, so as to find an object on a projection of the image; by applying a "CLAHE" filter, for "Contrast Limited Adaptive Histogram Equalization"; by applying a "Kmeans" filter, to determine the center of clusters and groups of samples around clusters, by applying a DFT filter, so as to perform a discrete, direct or inverse Fourier transformation of a vector, by calculating moments, by applying an "HuMoments" filter to calculate invariant Hu invariants, by calculating the integral of an image, by applying a Scharr filter, making it possible to calculate a derivative of the image by using a Scharr operator, by searching for the convex hull of points ("ConvexHull"), by finding points of convexity of a contour ("ConvexityDefects"), by comparison of shapes ("MatchShapes") ) by checking if points are in an outline ("PointPolygonTest"); By detection of Harris contours ("CornerHarris"); by searching for minimal eigenvalues of gradient matrices, to detect corners ("CornerMinEigenVal"); by applying a Hough transform to find circles in a grayscale image ("HoughCircles"); Active contour model: delineating an object outline from possibly noisy 2D image. By calculating a force field, called GVF ("gradient vector flow"), in a part of the image; Cascade classification ("CascadeClassification"); - By "Deepleraning". Preferably, the discriminant information is optimized by means of an optimization method according to the invention comprising steps C1 to C3. In optional step d), the actual acquisition conditions in step b) are roughly determined. In other words, the relative position of the image acquisition apparatus is determined at the moment when it has taken the updated image (position of the acquisition apparatus in the space and orientation of this apparatus). Step d) advantageously makes it possible to limit the number of tests on virtual acquisition conditions during step e), and thus makes it possible to considerably accelerate step e).
[0044] One or more heuristic rules are preferably used. For example, preferably, virtual acquisition conditions that can be tested in step e) are excluded, conditions that correspond to a position of the image acquisition apparatus behind the teeth or at a distance teeth greater than 1 m. In a preferred embodiment, as illustrated in FIG. 7, registration marks represented on the updated image, and in particular register marks 12 of the spacer, are used to determine a region of substantially conical space. delimiting virtual acquisition conditions that can be tested in step e), or "test cone". Specifically, preferably at least three registration marks 12 are not aligned on the spacer 10, for example, and their relative positions on the spacer are accurately measured. The registration marks are then marked on the updated image as previously described. Simple trigonometric calculations are used to roughly determine the direction in which the updated image was taken. A cone oriented in this direction, whose apex is at the level of the spacer and whose half-angle at the apex is preferably less than 100, preferably less than 50, for example 30 can then be defined as "cone of test". The half-angle at the top corresponds to a degree of uncertainty. The smaller the half-angle at the apex, the greater the probability that the virtual acquisition conditions corresponding to the actual acquisition conditions are outside the test cone. For example, when the updated image is taken perpendicular to the plane of the three registration marks on the spacer, it can be deduced that the acquisition device was substantially in a test cone whose axis is substantially perpendicular to this plan when taking the updated image. If the relative positions of the three registration marks on the updated image are different from those which the registration marks occupy on the spacer, the axis of the test cone in which is limited the search for the positioning of the device. acquisition during the acquisition of the updated image is inclined with respect to the plane of the registration marks, as shown in FIG. 7. In a particular embodiment, as illustrated in FIGS. 5a and 5c, the spacer comprises left and right independent parts, each comprising at least three registration marks, preferably at least four registration marks. A left test cone can thus be determined by means of the registration marks of the left part and a right test cone can be determined by means of the registration marks of the right part of the retractor. The virtual acquisition conditions that can be tested can then be limited to positions of the acquisition apparatus in the space belonging to these two test cones. It can also be considered that the best evaluation of the position of the acquisition apparatus corresponds to the average position between the best position in the left test cone and the best position in the right search cone. The position of the registration marks on the updated image also makes it possible to evaluate the attitude of the acquisition apparatus when capturing the updated image. For example, if it is known that two registration marks are substantially aligned in a horizontal direction when acquiring the updated image, the direction of the line containing these two points on the updated image provides an indication of the orientation. of the acquisition device under the actual acquisition conditions. Finally, the size and the surface of the registration marks on the updated image or their spacing can make it possible to evaluate the distance between the image acquisition apparatus and the teeth during the acquisition of the updated image, and therefore reduce the test cone to a truncated cone. In the optional step d), it is also possible to use data supplied by the acquisition apparatus and concerning its orientation, for example gyroscopic data.
[0045] Step d) allows only a rough evaluation of the actual acquisition conditions. Step d), however, makes it possible to determine a restricted set of virtual acquisition conditions that may correspond to the actual acquisition conditions, and, in this set, virtual acquisition conditions constituting the best starting point for the step el) described below. Step d) also makes it possible to detect updated images that are unsuitable for the continuation of the process, for example an updated image that would not reveal the registration marks. Preferably, the method is then repeated in step c) with a new updated image. Of course, the different methods that can be implemented in step d) can be combined. The objective of step e) is to modify the initial reference model until a final reference model is obtained which corresponds to the updated image. Ideally, the final reference model is therefore a three-dimensional numerical reference model from which the updated image could have been taken if this model had been real. Thus, a succession of reference models "to be tested" is tested, the choice of a reference model to be tested preferably being dependent on the level of correspondence of the reference models "to be tested" previously tested with the updated image. This choice is preferably made by following a known optimization method, in particular chosen from the metaheuristic optimization methods, in particular in the simulated annealing processes. In step el), it is determined that the reference model to be tested is the initial reference model during the first execution of step e2). In step e2), we first determine virtual acquisition conditions to be tested, that is to say a virtual position and orientation that can correspond to the actual position and orientation of the device. acquisition when capturing the updated image. The first virtual acquisition conditions to be tested may be random.
[0046] Preferably, they are chosen from the limited set determined in step d), and more preferably, correspond to virtual acquisition conditions corresponding, according to step d), to the virtual acquisition conditions more promising, that is to say constituting the best springboard to approach, as soon as possible, the actual acquisition conditions (step e21)).
[0047] The image acquisition apparatus is then placed virtually in the virtual acquisition conditions to be tested in order to acquire a reference image of the reference model under these virtual acquisition conditions to be tested. The reference image therefore corresponds to the image that the image acquisition apparatus would have taken if it had been placed, with respect to the reference model to be tested, under the virtual acquisition conditions to be tested ( step e22)).
[0048] If the updated image was taken at the same time as the reference model was made, and if the virtual acquisition conditions are exactly the actual acquisition conditions, then the reference image is exactly superimposable to the image updated. The differences between the updated image and the reference image result from errors in the evaluation of the virtual acquisition conditions (if they do not correspond exactly to the actual acquisition conditions) and the movement of the teeth between the step b) and the reference model to be tested. To compare the updated and reference images, the discriminant information on these two images is compared. More precisely, a reference map representing the discriminant information (step e23) is produced from the reference image.
[0049] The updated and reference maps, both of which are based on the same discriminant information, are then compared and the difference between these two maps is evaluated by means of a score. For example, if the discriminant information is the contour of the teeth, one can compare the average distance between the points of the contour of the teeth which appears on the reference image and the points of the corresponding contour which appears on the updated image, the score being all the higher as this distance is small. The score may be for example a correlation coefficient. The score is then evaluated by means of a first evaluation function. The first evaluation function makes it possible to decide whether the cycling on step e2) must be continued or stopped. The first evaluation function may for example be equal to 0 if the cycling must be stopped or equal to 1 if the cycling must continue. The value of the first evaluation function may depend on the score achieved. For example, it may be decided to continue cycling on step e2) if the score does not exceed a first threshold. For example, if an exact match between the updated and reference images leads to a score of 100%, the first threshold may be, for example, 95%.
[0050] Of course, the higher the first threshold, the better the accuracy of the evaluation of the virtual acquisition conditions if the score manages to exceed this first threshold.
[0051] The value of the first evaluation function may also depend on scores obtained with virtual acquisition conditions previously tested. The value of the first evaluation function may also depend on random parameters and / or the number of cycles of step e2) already carried out.
[0052] In particular, it is possible that, despite the repetition of the cycles, it is not possible to find virtual acquisition conditions that are sufficiently close to the actual acquisition conditions for the score to reach said first threshold. The first evaluation function can then lead to the decision to leave cycling even though the best score obtained has not reached the first threshold. This decision may result, for example, in a number of cycles greater than a predetermined maximum number. A random parameter in the first evaluation function may also allow tests to be continued for new virtual acquisition conditions, although the score appears satisfactory. The evaluation functions conventionally used in metaheuristic optimization processes, in particular in simulated annealing processes, can be used for the second evaluation function. If the value of the first evaluation function indicates that it is decided to continue the cycling on step e2), the virtual acquisition conditions tested (step e25) are modified and a cycle is restarted (step e2) ) of making a reference image and a reference map, then comparing this reference map with the updated map to determine a score. The modification of the virtual acquisition conditions corresponds to a virtual displacement in space and / or to a modification of the orientation of the acquisition apparatus. This modification can be random, provided however that the new virtual acquisition conditions to be tested always belong to the set determined in step d). The modification is preferably guided by heuristic rules, for example by favoring the modifications which, according to an analysis of the previous scores obtained, appear the most favorable to increase the score. The cycling on e2) is continued until the value of the first evaluation function indicates that it is decided to exit this cycling and to continue to step e3), for example if the score reaches or exceeds said first threshold.
[0053] The optimization of the virtual acquisition conditions in step e2) is preferably performed using a metaheuristic method, preferably a simulated annealing algorithm. Such an algorithm is well known for nonlinear optimization. If we have left the cycle on the step e2), without a satisfactory score could be obtained, for example without the score could reach said first threshold, the process can be stopped (failure situation) or resumed in step c) with new discriminant information and / or with a new updated image. The process can also be continued with the virtual acquisition conditions corresponding to the highest score achieved. A warning may be issued to inform the user of the error on the result.
[0054] If we left the cycling on the step e2) while a satisfactory score could be obtained, for example because the score reached, or even exceeded said first threshold, the virtual acquisition conditions substantially correspond to the conditions of actual acquisition. However, differences may remain, particularly if teeth have moved between steps a) and b). The correlation between the updated and reference images can then be further improved by repeating step e2), the reference model to be tested then being modified by moving one or more tooth models (step e3)). The search of the reference model optimally approximating the positioning of the teeth during the acquisition of the updated image can be performed as the search for the virtual acquisition conditions approximating at best the actual acquisition conditions (step e2)). In particular, the score is evaluated by means of a second evaluation function. The second evaluation function makes it possible to decide whether the cycling on steps e2) and e3) must be continued or stopped. The second evaluation function may for example be equal to 0 if the cycling must be stopped or equal to 1 if the cycling must continue.
[0055] The value of the second evaluation function preferably depends on the best score obtained with the reference model to be tested, that is to say the differences between the updated and reference maps, in the virtual acquisition conditions approximating to better said actual acquisition conditions. The value of the second evaluation function may also depend on the best score obtained with one or more reference models previously tested.
[0056] For example, it may be decided to continue cycling if the score does not exceed a second minimum threshold. The value of the second evaluation function may also depend on random parameters and / or the number of cycles of steps e2) and e3) already carried out.
[0057] The evaluation functions conventionally used in metaheuristic optimization processes, in particular in simulated annealing processes, can be used for the second evaluation function. If the value of the second evaluation function indicates that it is decided to continue cycling on steps e2) and e3), the reference model to be tested is modified and a cycle is restarted (steps e2) and e3)) with the new reference model to test. The modification of the reference model to be tested corresponds to a displacement of one or more models of teeth. This change can be random. The modification is preferably guided by heuristic rules, for example by favoring the modifications which, according to an analysis of the previous scores obtained, appear the most favorable to increase the score. Preferably, the displacement of a tooth model that has the greatest impact on the score is sought, the reference model to be tested is modified by moving this tooth model, then the cycling is continued on the steps e2) and e3 ) in order to optimize the score. We can then look for the other tooth model that has the greatest impact on improving the score, and again look for the optimal displacement of this other tooth model on the score. We can continue with each model of tooth. Then, it is possible to resume a cycle on all the tooth models and continue thus until a score higher than the second threshold. Of course, other strategies can be used to move one or more tooth models in the reference model to be tested and search for the maximum score. The cycling on steps e2) and e3) is continued until the value of the second evaluation function indicates that it is decided to exit this cycling and to continue to step f), for example if the score reaches or exceeds said second threshold. Searching for a reference model with cycling on steps e2) and e3) to search the positions of the tooth models that optimize the score is preferably performed using a metaheuristic method, preferably a simulated annealing algorithm. Such an algorithm is well known for nonlinear optimization. If we have left the cycling on steps e2) and e3) without a satisfactory score being obtained, for example without the score being able to reach said second threshold, the process can be stopped (failure situation) or taken again in step c) with new discriminant information and / or with a new updated image. If it is decided to restart the process in step c) from another discriminant information and / or another updated image because the first threshold or the second threshold has not been reached, the choice the new discriminant information and / or the new updated image may depend on the scores obtained previously, in order to favor the discriminant information and / or the updated image which, with regard to these scores, appear the most promising. New discriminant information, obtained for example by combining other discriminant information already tested, can be used. If necessary, it may also be requested to acquire one or more new updated images. Preferably, indications are provided to guide the positioning of the acquisition apparatus for capturing this new updated image. For example, the patient may be told that he should take a picture of the right side of his lower arch.
[0058] If we left cycling on steps e2) and e3) without a satisfactory score could be obtained, the process can be continued with the reference model and the virtual acquisition conditions corresponding to the highest score achieved. A warning may be issued to inform the user of the error on the result. If we have left the cycling on steps e2) and e3) while a satisfactory score could be obtained, for example because the score has reached or even exceeded said second threshold, the virtual acquisition conditions substantially correspond to the conditions actual acquisition and tooth models in the obtained reference model (called "final reference model") are substantially in the position of the patient's teeth at the time of step b).
[0059] In step f), the final reference model, resulting from the displacement optimization of the tooth models, is compared with the initial reference model. The final reference model corresponds substantially to the updated image. The comparison of step f) thus makes it possible to observe the differences between the positioning of the teeth in step a) (initial reference model) and when acquiring the updated image (step b)). The method thus makes it possible to precisely determine, for each of the teeth, the movements between these two steps.
[0060] By repeating steps b) and following, it is also possible to evaluate the rate of evolution of the position of the teeth, and thus to measure, for example, the effectiveness of orthodontic treatment. A method of controlling the positioning of teeth according to the invention can for example be used to remotely follow the evolution of an orthodontic treatment, and thus optimize the appointments of patients in their orthodontists.
[0061] In a preferred embodiment, the control method according to the invention is implemented several times for the same patient, preferably successively with several discriminant information, preferably more than 2, more than 3, more than 5 discriminant information for the same patient. each updated image and / or with several updated images, preferably more than 2, more than 3, more than 5 updated images. The evaluation of the displacement of a tooth can thus be refined taking into account the different scores obtained. The comparison of these scores also makes it possible, if necessary, to discard the discriminating information and / or the unsatisfactory updated images. Depending on the measured displacement, practical information can be generated. If the displacement is small, this practical information may be that no action is to be taken. On the contrary, if one or more teeth have moved significantly, the information may be to plan a visit to the dentist or orthodontist. Preferably, the practical information depends on the degree of movement of the teeth. In one embodiment, an appointment may be automatically made to the dentist or orthodontist, depending on the amplitude and / or nature of the detected movements.
[0062] In one embodiment, the practical information is used to change the time interval after which the patient will need to be notified that a new updated image is to be created. In one embodiment, the individual device makes it possible to display images, or even a sequence of images showing the positioning of the teeth at different dates. These images can be presented in the form of an animation, for example in the form of a slide show or a movie.
[0063] Preferably, the image acquisition apparatus is a telephone which makes it possible to transmit the results obtained by the implementation of the method, preferably in a secure manner. The communication may for example be carried out, at least in part, by the air way, preferably according to at least one protocol chosen from the edge, 3G, 4G, udmsa, hpdmsa, bluetooth, and wifi protocols, or by any other protocol, suitable for mobile or mobile devices, by wired synchronization with the personal computer, or by optical transmission. As it is now clear, a method of controlling the positioning of teeth according to the invention allows a precise and effective control of the positioning of the patient's teeth, substantially without constraint for the patient. In particular, simple photographs taken without special precautions, for example with a mobile phone, is sufficient. The patient can therefore easily implement this method. DETAILED DESCRIPTION OF A METHOD FOR CONTROLLING THE FORM OF TOOTHES The invention also relates to a method for controlling the shape of teeth of a patient.
[0064] In step a), however, the definition of tooth models is not essential for this control. Preferably, in step e), it is sought, for each updated image, a final reference model corresponding to the shape of the teeth during the acquisition of the updated image, the search being preferably carried out by means of a metaheuristic method, preferably by simulated annealing, in particular by means of one of the metaheuristic methods described above. Preferably, as described for step e), this search comprises two nested optimization loops. In the first optimization operation, firstly, in a reference model to be tested that is initially the initial reference model, virtual acquisition conditions that best correspond to the actual acquisition conditions are optimized. In particular, the virtual position of the acquisition apparatus is sought with respect to the reference model to be tested which offers the view of this reference model to be tested, that is to say the reference image, which is closest to the updated image.
[0065] During the second optimization operation, the reference model to be tested is then modified, the optimization operation is restarted first, and then these two operations are repeated until the reference model to be tested and the virtual position are found. of the acquisition apparatus that make it possible to obtain the reference image that is closest to the updated image. These operations are similar to those described for the method of controlling the positioning of the teeth and optional features of the latter control are optionally applicable. However, according to the method of controlling the positioning of the teeth described above, the modification of the reference model results from a displacement of one or more tooth models. No deformation of the tooth models or the initial reference model is necessary.
[0066] To control the shape of the teeth, the modification of the reference model results from a modification of the shape of the reference model to be tested, in particular of one or more models of teeth. No displacement of the tooth models is necessary. Of course, it is preferable to perform both types of modifications of the reference model to be tested in order to determine a final reference model that takes into account both the displacement of the teeth and their deformation. For example, it is possible to implement a third optimization operation relating to the movement of the teeth and framing the first two optimization operations, the second optimization relating to the shape of the tooth models or the reference model to be tested. It is also possible to implement only the first two optimization operations, possibly simultaneously modifying the shape and position of the tooth models during the second optimization operation. It is also possible to implement a third optimization operation relating to the shape of the tooth models or of the reference model to be tested and framing the first two optimization operations, the second optimization operation relating to the displacement of the models of teeth. For example, we first look for a final reference model "to test" taking into account, at best, the displacement of the tooth models, the final reference model to be tested corresponding to the final reference model of a step e) d a method of controlling the positioning of the teeth described above, then it is investigated whether a deformation of the final reference model to be tested may lead to a better match with the updated image. For this search, the final reference model to be tested is deformed, the first two optimization operations are repeated, then, depending on the agreement obtained, the search is stopped or it is continued by performing a new deformation of the reference model. final test and restarting an execution of the first two optimization operations. Preferably, the first optimization operation and / or the second optimization operation and / or the third optimization operation, preferably the first optimization operation and the second optimization operation and the third optimization operation. implement a metaheuristic method, preferably a simulated annealing, in particular one of the metaheuristic methods mentioned above. Preferably, to control the deformation of the teeth, step e) comprises - a first optimization operation making it possible to search for virtual acquisition conditions that best correspond to the actual acquisition conditions in a reference model to be tested determined at from the initial reference model, and - a second optimization operation for searching, by testing a plurality of said reference models to be tested, the reference model corresponding best to the shape of the teeth of the patient during the acquisition the image updated in step b), preferably corresponding best to the shape and positioning of the patient's teeth when acquiring the image updated in step b). Preferably, a first optimization operation is performed for each test of a reference model to be tested during the second optimization operation. Step e) may notably comprise the following steps: el) definition of the reference model to be tested as the initial reference model and then, é2) according to the following steps, test of virtual acquisition conditions with the model of reference to be tested for finely approximating said actual acquisition conditions; e21) determination of virtual acquisition conditions to be tested; é22) performing a two-dimensional reference image of the reference model to be tested in said virtual acquisition conditions to be tested; é23) processing the reference image to realize at least one reference map representing said discriminant information; e24) comparing the updated and reference maps to determine a value for a first evaluation function, said value for the first evaluation function depending on the differences between said updated and reference maps and corresponding to a decision of continuing or stopping the search for virtual acquisition conditions approximating said actual acquisition conditions more accurately than said virtual acquisition conditions to be tested determined at the last occurrence of step e21); é25) if said value for the first evaluation function corresponds to a decision to continue said search, resumed in step e21) by modifying the virtual acquisition conditions to be tested; é3) otherwise determining a value for a second evaluation function, said value for the second evaluation function depending on the differences between the updated and reference maps in the virtual acquisition conditions approximating at best the said conditions of evaluation. the actual acquisition and resulting from the last occurrence of step e2), said value for the second evaluation function corresponding to a decision to continue or stop searching for a reference model approximating the shape, and possibly the positioning of the teeth during the acquisition of the updated image with more accuracy than said reference model to be tested used at the last occurrence of the step é2), and if said value for the second function of evaluation corresponds to a decision to continue the search, modification of the reference model to be tested by deformation of one or more models of teeth, or of the reference model to be tested, and possibly by moving one or more models of teeth, then resumed in step e2). At the end of this process, we arrive at a reference model to be tested, called "final reference model", which corresponds to the initial reference model distorted to correspond best to the updated image.
[0067] The comparison of the initial and updated reference models includes the comparison of the spatial coordinates of the points of the surfaces defined by these two reference models.
[0068] It can thus be deduced any possible changes in shape between step a) and step b). Preferably, a mapping is made of the tooth showing the shape changes. Preferably, as shown in FIG. 8, the color of an area of the map is a function of the extent of shape change of this zone. The mapping of Figure 8 shows in particular an area 16 indicating a break of a tooth. Of course, the method of controlling the shape of teeth of a patient can be used to detect an addition or a subtraction of material, but also a constant volume deformation. This method also makes it possible to detect movements of teeth, even without a tooth model. However, in the absence of a tooth model, it does not make it possible to distinguish the deformations of the teeth on the one hand and the movements of the teeth on the other hand. Detailed description of a method for checking the appearance of the teeth Controlling the evolution of the color of teeth from photographs taken in positions of the camera or in different light environments shows that this comparison does not allow not to evaluate a change in the appearance of these teeth. Such control of the color of the teeth therefore requires special precautions, in particular to accurately define the position of the camera and its light environment.
[0069] There is therefore a need for a method for controlling the color, and more generally an aspect property, of the teeth in a simpler way, and in particular by avoiding these particular precautions. An object of the invention is to meet this need. The invention provides a method of controlling a patient's teeth appearance property, said method comprising steps A. to E. described above, shown in Figure 9. As will be seen in more detail in the rest of the description, this method makes it possible to evaluate whether the appearance, in particular the color of one or more of the teeth, has been modified, even when the conditions for acquiring photographs of teeth of a patient are not not predefined, for example because the photographs were taken in a bright environment or in any position of the acquisition apparatus, in particular by the patient. "Aspect property" means a property relating to appearance. The aspect property may be in particular selected from the group consisting of color, opalescence, fluorescence, gloss, transparency, and combinations of these properties. By "aspect" is meant a value or set of values to quantify an aspect property. Unless otherwise indicated, the "aspects" mentioned in the present description relate to the appearance property that the method allows to control.
[0070] Steps A. and B. Steps A. and B. can be performed as step b) described above. Steps A. and B. are preferably performed by the patient or a close relative of the patient, but may be performed by a dentist. The time interval between these steps may be that described above between steps a) and b), for example greater than 1 week, 2 weeks, 1 month or 3 months. The first acquisition apparatus may be the same or different from the second acquisition apparatus. It can be an acquisition device selected from those that can be used for step b), including a camera or a mobile phone. Preferably, acquisitions in steps A. and / or B. are performed using a flash. The results are improved. Preferably, the initial image and / or updated is overexposed. The reference gauges used for each of the steps A. and B. have the same aspect. Preferably, during each of the steps, they are arranged in the same position relative to the teeth of the patient.
[0071] Preferably, dental spacers are used for each of steps A. and B. These spacers may be the same or different. Preferably, the reference gauge is carried by a spacer for at least one of steps A. and B., preferably for each of steps A. and B. Preferably, even if the spacers used for each of steps A. and B. B. are different, the reference gauges are arranged on the spacers in the same position relative to the opening 14 of the spacer which reveals the teeth of the patient (Figure 5a). Preferably, the reference gauge is disposed on the spacer so as to be close to the teeth whose appearance property must be controlled. Preferably, the reference gauge is disposed less than 3 cm, preferably less than 2 cm, preferably less than 1 cm of the portion of the spacer to be introduced into the mouth of the patient. Preferably, each spacer comprises several reference gages, identical or different. Preferably, several different reference gages of the same spacer have different aspects. The conclusions drawn from the comparison of normalized images can be advantageously richer. A reference gauge may be for example a markable point on the spreader and the appearance of which is known, for example whose color parameters L *, and / or a * and / or b *, measured according to the NF ISO standard. 7724, are known. The reference gauge can be in particular a marking mark of a spacer as described above.
[0072] The acquisition conditions specify the position in the space and / or the orientation of the acquisition apparatus with respect to the retractor. To improve the accuracy of the aspect control, it is preferable that the acquisition conditions are substantially the same in steps A. and B. For example, it is preferable that the two images are taken substantially from the front. Preferably, the image acquisition apparatus used for at least one, preferably for each of the steps A. and B. comprises polarizing means facilitating its positioning relative to the patient before acquiring the image. The polarizing means preferably interact with marking marks disposed on the spacer. Preferably, the acquisition apparatus is programmed so as to, in real time, locate the marking marks on the spacer, analyze their relative positions or their dimensions and, consequently, inform the user of the apparatus of acquisition so that it modifies accordingly the position of the acquisition apparatus with respect to the patient's teeth. These polarizing means may have one or more of the characteristics of the polarizing means described above for step b).
[0073] Preferably, for at least one, preferably for each of steps A. and B., an acquisition kit according to the invention is used and, preferably, an acquisition method comprising steps (a) to (e). . Preferably, the target acquisition conditions are the same in the memory of the first and second acquisition apparatuses so that the acquisition apparatus guides its user so that the initial and updated images are taken under acquisition conditions. substantially identical. Preferably, the target acquisition conditions are determined according to the teeth whose appearance property is to be controlled. For example, the target acquisition conditions preferably correspond to an image taken in front of the patient for control on an incisor and they preferably correspond to a lateral image for a control on a molar. Step C. Step C. consists in normalizing, that is, "correcting" the initial image and / or the updated image so that, after correction, the representations of the reference gauge on these images have the same aspect. As the reference gauge has not changed in appearance between steps A. and B., the possible differences in appearance presented by the representations of the teeth on the standardized initial and updated images thus correspond to actual differences in appearance said teeth. We first look for the reference gauge on the initial image and on the updated image.
[0074] A simple image analysis is sufficient for this purpose. Normalization can be performed on the initial image only to modify the representation of the reference gauge so that its appearance is identical to that of the representation of said reference gauge on the updated image. The normalization can alternatively be performed on the updated image only in order to modify the representation of the reference gauge so that its appearance is identical to that of the representation of said reference gauge on the initial image. Finally, the normalization can be performed on the updated image and on the initial image in order to modify the representations of the reference gages so that their aspects are identical to that of a standard gage.
[0075] Normalization of an image is a technique well known in the field of image processing. White balance is an example of normalizing images.
[0076] Step D. Before or after step C., it is necessary to identify, on each of the initial and updated images, a region of the teeth whose aspect evolution is to be evaluated. The use of registration marks or reference gauges is possible, but remains unclear. Preferably, the initial and updated images are analyzed in order to represent discriminant information, of the type of those described above, for example the contour of the teeth. The initial and updated image analysis may comprise one or more characteristics of step c), particularly relating to the nature of the discriminant information and the processing for determining the discriminant information. The discriminant information is preferably optimized by means of an optimization method comprising steps C1 to C3. We then seek discriminating information common to both initial and updated images.
[0077] Discriminant information common to both initial and updated images can then serve as a repository for locating said region on these two images. For example, the outline of the gums may have a succession of "spikes" between the teeth. This contour depends on the teeth considered and can therefore serve as a reference. In an improved embodiment, the initial and updated images are identified with respect to a reference model, preferably made according to step a) (initial reference model) or resulting from the implementation of a method of control of the shape and / or positioning of the teeth according to the invention (final reference model). This identification can be performed as described above to identify the updated image in the context of the methods for controlling the shape and / or positioning of the teeth. Unlike these methods, the modification of the initial reference model to arrive at the final reference model is however optional. To locate an image with respect to the reference model, it is sufficient to look for the virtual acquisition conditions in which the acquisition apparatus acquired said image by observing said reference model. This search is preferably performed using a metaheuristic method, such as those described above.
[0078] For this research, a method for evaluating the actual acquisition conditions according to the invention, described below, is preferably used. This method is preferably implemented for each of the initial images and updated using the reference model. It allows to "project" these images on the reference model and thus to locate a point of these images on the reference model. A region of the teeth whose aspect evolution is to be evaluated can thus be identified with great precision on each of the initial and updated images. Step E. It is then possible to measure the aspects of said region on each of the initial and updated images and compare them to detect and evaluate differences in the aspect property. A method of controlling the appearance of the teeth according to the invention can be used for therapeutic or non-therapeutic purposes. It can in particular be used to: - detect and / or measure a color change of the teeth or the appearance and / or evolution of tasks on the teeth, or detect and / or measure calcification of the teeth; - check the effects on the appearance of the teeth of a food habit or a food hygiene or treatment, for example a bleaching treatment, or a product, especially a toothpaste, in particular to whiten teeth or to fight against calcification or the appearance of tasks. For example, a method of controlling the appearance of teeth according to the invention can be used to check the effects on the appearance of teeth chewing chewing gum or ingestion of coffee or tea, or tobacco or drug use, or brushing teeth.
[0079] In a preferred embodiment, it is sufficient for the patient to take regular photographs with his mobile phone to constitute updated images. Preferably, thanks to an application loaded in this phone, he can then compare the aspects of the teeth on these photographs.
[0080] In one embodiment, the application standardizes the photographs in order to make them comparable, then proposes a dynamic visualization of the corrected photographs, for example in the form of a slide show or a film. DETAILED DESCRIPTION OF A METHOD FOR EVALUATING REAL ACQUIRING CONDITIONS In particular for implementing a method for controlling the shape, positioning and / or appearance of teeth according to the invention or for optimizing the quality of a discriminant information, the invention provides a method for evaluating, from a two-dimensional image of the dental arches of a patient, called "acquired image", actual acquisition conditions (position of the patient). apparatus for acquiring in space and orientation of said acquired image, said method comprising the steps of: 001) providing a three-dimensional reference numerical model of at least a portion of an arch of the patient preferably an arch, preferably two arches of the patient, 002) analysis of the acquired image and production of a map relating to a discriminant information, called "acquired map"; 003) searches for virtual acquisition conditions optimally approximating said actual acquisition conditions, according to the following steps 01) to 05): 01) optionally, determining coarse virtual acquisition conditions approximating said acquisition conditions real, preferably by analysis of the representation, on the acquired image, of a spacer used during the acquisition of the acquired image; 02) determination of virtual acquisition conditions to be tested; 03) performing a two-dimensional reference image of the reference model observed in the virtual acquisition conditions to be tested; 4) processing the reference image to produce at least one reference map representing said discriminant information; 5) comparison of the acquired and reference cards so as to determine a value for an evaluation function, said value for the evaluation function depending on the differences between said acquired and reference cards and corresponding to a decision to continue or to stop the search for virtual acquisition conditions approximating the actual acquisition conditions with more accuracy than said virtual acquisition conditions to be tested; 06) if said value for the evaluation function corresponds to a decision to continue said search, modification of said virtual acquisition conditions to be tested, then resumption at step 03); otherwise, evaluation of the actual acquisition conditions by said virtual acquisition conditions to be tested. In the evaluation method, the modification made to the virtual acquisition conditions to be tested in step 06) is preferably carried out by means of a metaheuristic method, preferably by simulated annealing, preferably by means of one of the metaheuristic methods mentioned above. An evaluation method according to the invention is preferably used whenever it is necessary to evaluate the actual acquisition conditions of an image. This image, which can in particular be a refreshed image acquired during a step b) or B. or an initial image acquired during a step A., is called "acquired image". The realization of the reference model in step 001) may include one or more of the same optional features of step a). Acquiring the acquired image may include one or more of the features, even optional ones, of step b). Preferably, it implements an acquisition kit according to the invention, and preferably an acquisition method according to the invention. The step 01) for determining the coarse virtual acquisition conditions may include one or more of the same optional features of step c). Steps 02) to 06) may include one or more of the same optional features of steps e21) to e25), respectively. Detailed Description of a Discriminant Information Optimization Method A method for optimizing a discriminant information according to the invention is intended to improve the reliability of an initial discriminant information extracted from a two-dimensional image of dental arches. a patient, or "acquired image", in particular an initial image resulting from a step A. or a refreshed image resulting from a step B. or b), acquired under real acquisition conditions. This method is based on a three-dimensional numerical reference model of at least a portion of an arch of the patient, in particular an initial reference model of a step a). As illustrated in FIG. 10, it comprises the following steps: C1. Evaluation of the quality of the initial discriminant information and of a quality threshold, filtering so as to retain only the initial discriminant information, preferably any the initial discriminant information having a quality higher than the quality threshold, and definition of the "discriminant information to be tested" as the discriminant information selected; C2. test of the concordance (in English "matching") between the discriminant information to be tested and the reference model; C3. according to the result and a function of evaluation of the test result: addition of discriminant information not retained to the discriminant information to be tested and / or deletion of discriminant information in the discriminant information to be tested, then resuming step C2. or, - definition of the optimal discriminant information as the discriminant information to be tested. The discriminant information may be in particular any of the discriminant information described above. For example, the discriminant information may be contour information.
[0081] The initial discriminant information conventionally results from the analysis of the acquired image, as described for step c). The methods according to the invention that use such initial discriminant information implement optimizations that provide better results if the discriminant information is both abundant and of good quality. An objective of the optimization process is therefore to improve the quality of the initial discriminant information. In step C1, the quality of the initial discriminant information is evaluated. In the example of a contour, the contrast analysis provides for example more or less reliable information: an area of high contrast can be likened to an area corresponding to an outline with a high probability and the quality of the points of this zone will be high.
[0082] On the contrary, a zone of low contrast, for example a fuzzy zone, can be likened to an area corresponding to a contour with a low probability and the quality of the points of this zone will therefore be low. In this example, the probability for a point of the image acquired to belong to the contour can be chosen as an indicator of the "quality" of the discriminant information. A quality threshold is used to filter the initial discriminant information. If the quality threshold is high, the discriminant information retained after filtering will be small, but very reliable. If the quality threshold is low, the discriminant information retained will be abundant, but unreliable. In the example of a contour information, the analysis of the image will then lead to retaining "false" contour points, that is to say, points that, because of the analysis, will be mistakenly considered to belong to the contour of the teeth and gums.
[0083] In a preferred embodiment, the quality threshold is high in order to retain only highly reliable discriminant information to be tested. In step C2., The concordance between the discriminant information to be tested and the reference model is tested. Preferably, an "acquired" card of the discriminant information to be tested resulting from the processing of the acquired image is produced. Preferably, the following steps are followed according to steps 01) to 06), and in particular the following steps: 2) determination of virtual acquisition conditions to be tested; 3) producing a two-dimensional reference image of the reference model observed in the virtual acquisition conditions to be tested; 4) processing the reference image to produce at least one reference map representing discriminant information; 5) comparison of the acquired and reference cards so as to determine a value for an evaluation function, said value for the evaluation function depending on the differences between said acquired and reference cards and corresponding to a decision to continue or to stop the search for virtual acquisition conditions approximating the actual acquisition conditions with more accuracy than said virtual acquisition conditions to be tested; 06) if said value for the evaluation function corresponds to a decision to continue said search, modification of said virtual acquisition conditions to be tested, then resumption at step 03); otherwise, evaluation of the actual acquisition conditions by said virtual acquisition conditions to be tested. In step 04), the processing of the reference image makes it possible to produce a reference map representing said discriminant information. The criteria for selecting the discriminant information represented on the reference card may be identical or different from those used to select the discriminant information to be tested. Preferably, the discriminant information represented on the reference map is selected with the same criteria as the discriminant information to be tested. In the example of a contour, the processing of the reference image may consist in retaining the points of the reference image corresponding to an outline with a high probability. The probability of a point of the reference image to belong to the contour can be determined as for the processing of the acquired image and also serve as an indicator of the quality of the discriminant information. The quality threshold may also be identical to that used for processing the acquired image. The contour shown on the reference map is then similar to that shown on the acquired map, and in particular has a substantially identical length. Steps 01) to 06) make it possible to determine, with the reference model, virtual acquisition conditions approximating the actual acquisition conditions of the acquired image. The observation of the reference model in these virtual acquisition conditions thus provides a view that best corresponds to the acquired image. The search for virtual acquisition conditions, however, is based on the discriminant information to be tested. The degree of correspondence therefore depends on the discriminant information to be tested. The higher the quality and quantity of the discriminant information to be tested, the better the degree of correspondence between the reference model view in the virtual acquisition conditions and the acquired image, and the higher the degree of concordance between the discriminant information to be tested and the reference model. The degree of concordance can be measured, for example, by the reciprocal of the difference between the reference map relative to the reference model image observed in the virtual acquisition conditions, which best approximates the actual acquisition conditions in consequence of the execution of steps 01) to 06), and - the "acquired" card representing the discriminant information to be tested corresponding to the acquired image weighted by the amount of discriminant information to be tested.
[0084] For an outline, for example, the degree of concordance can be the ratio of the number of points that belong to both the contour of the reference map and the contour of the acquired map, to the total number of points of the contour of the acquired map. , or the product of the inverse of the average distance between the contours represented on said acquired and reference maps, and the length of the contour represented on the acquired map. The "best" approximation of the actual acquisition conditions from discriminant information to be tested can be evaluated by a result or "score", for example by the degree of agreement. The cycle of steps C2. and C3. is intended to optimize this result by acting on the discriminant information to be tested.
[0085] This optimization is similar to that used for the methods for controlling the positioning and / or shape of the teeth. These methods, however, act on the initial reference model, by displacement of the tooth models and / or by deformation of the reference model, whereas the process of optimization of the discriminant information acts on the discriminant information used to establish the map acquired.
[0086] The operation performed in step C3. is determined by a function of evaluating the result of the test of step C2. Preferably, the evaluation function takes into consideration results obtained during cycles C2.-C3. precedents. In particular, the process can be stopped if the evaluation function indicates that the continuation of C2.-C3 cycles. does not improve the result, for example because one or more cycles C2.-C3. did not improve it or did not significantly improve it. The discriminant information tested during the C2.-C3 cycle. leading to the best result is then considered optimal. Otherwise, a new cycle C2.-C3. can be started, after modification of the discriminant information to be tested. The modification to be made to the discriminant information that has just been tested may consist of an addition or a deletion of discriminant information. An addition of discriminant information may for example be decided if the last result is the best obtained so far and if, according to the evaluation function, the result can be further improved. Preferably, the added discriminant information is one which, among the discriminant information not retained in step C1 and which has not yet been tested, has the best quality. For example, when the discriminant information is contour information, the addition of discriminant information may include adding unsaved image points initially, never before added and whose quality, as evaluated by the step Cl., is the highest, that is to say the addition of which is most likely to improve the result of the test of step C2. Discriminatory information suppression can for example be decided if the last result is worse than the previous one. In particular, the discriminant information added during the previous cycle can be deleted and an addition of another discriminant information can be performed, as described above. The determination of the discriminant information to be added and / or deleted may be random. However, it preferably results from the implementation of a metaheuristic method, preferably by simulated annealing, preferably of the type described above. EXAMPLE By way of example, FIG. 11 represents, superimposed on the acquired image, a reference map relating to a reflection information (discriminant information). The acquired image, preferably acquired by means of an acquisition kit according to the invention, is a photograph taken in a particular position and orientation of the camera. This position and this orientation constitute the actual acquisition conditions of the acquired image. The person skilled in the art knows that, on the acquired image, the higher the brightness of a point, the higher the probability that this point belongs to a reflection zone. The brightness 20 can therefore serve as an indicator of the "quality" of the reflection information. The filtering in step C1 may consist in retaining only the zones of the acquired image that have a brightness greater than a quality threshold, for example 70%. The acquired map represents these zones, which constitute the discriminant information to be tested. In step C2., Steps are preferably performed according to steps 01) to 06) to test whether the retained areas agree with the observation of the reference model. In step 01), the acquired image is analyzed to roughly evaluate the actual acquisition conditions by virtual acquisition conditions. This evaluation preferably results from an analysis of the position and / or the shape of the representation, on the acquired image, of identification marks of a spacer used during the acquisition. The roughly evaluated virtual acquisition conditions may constitute the "virtual acquisition conditions to be tested" in step 02). In step 03), by observing the reference model from virtual acquisition conditions to be tested, a reference image is obtained.
[0087] In step 04), as shown in FIG. 11, vectors (black lines 20), all of the same length, perpendicular to the faces of the reference model can be projected onto the reference image. Circles 22 represent these vectors when viewed along their length. The reference map is thus constituted by these black lines 20 and circles 22. Those skilled in the art know that the circles 22 normally correspond to areas of the image corresponding to reflections. On the reference map, the discriminant information, namely the reflection information, is thus represented by the black lines 20 and by the circles 22, the inverse of the length of the black lines being able to serve as an indicator of the "quality" of the reflection information on the reference map, a circle corresponding to zero length, and therefore to a maximum quality. In step 05), a comparison of the acquired and reference cards may for example consist of checking whether the lines 20 and the circles 22 are inside zones of the acquired map (which initially correspond to a brightness greater than 70 %). The evaluation function can be for example the ratio R between the difference between the number of circles 22 and the number of lines which are inside zones of the acquired image and the total number of circles. The decision may be to continue the search by modifying the virtual acquisition conditions to be tested until reaching a maximum for the acquisition function. In step 06), if this maximum is considered as reached, it leaves the loop of steps 03) to 06). Otherwise, it is determined, preferably by means of a metaheuristic method, a change to be made to the virtual acquisition conditions to be tested and step 03 is repeated.
[0088] At the output of steps 03) to 06), the ratio R is therefore maximal for this acquired image, for example 95%. This ratio R then represents the result of the concordance test performed in step C2. In step C3, this result is evaluated by means of an evaluation function. This evaluation function preferably determines whether the result is optimal or not. If the result is considered optimal, for example because no better result can be obtained after several cycles of steps C2. - C3., It is considered that the areas of the corresponding acquired map constitute optimal discriminant information.
[0089] Otherwise, the acquired map is modified, for example by adding points of the acquired image, for example by adding points which have a brightness greater than 71%. This addition leads to the addition of circles in the zones of the acquired map, which improves the ratio R, but also to the addition of black lines, which degrades the ratio R. Conversely, it is possible to extract the points with a brightness greater than 69%. This deletion leads to the suppression of circles in the zones of the acquired map, which degrades the ratio R, but also to the suppression of black lines, which improves the ratio R. The modification to bring is preferably guided by a method metaheuristic.
[0090] From the new acquired map, which defines the discriminant information to be tested, it is repeated in step C2. The cycling of steps C2. and C3. can be continued to determine an optimal result. The discriminant information to be tested is then considered optimal. As it is now clear, a method for optimizing a discriminant information according to the invention makes it possible to construct discriminating information of good quality and abundant. In particular, it allows, starting from a partial initial contour, but of good quality, to gradually build a more complete contour but always of good quality. Of course, the invention is not limited to the embodiments described above and shown. In particular, unless otherwise indicated, the optional features described in the context of a step of a first method according to the invention are applicable in the context of a similar step or bearing the same reference of a second method according to the invention. invention.
[0091] The method for controlling the positioning and / or shape of the teeth may be implemented successively for each of the two arches or simultaneously for the two arches. In addition, for these methods, several different devices can be implemented. For example, the acquisition can be performed with a mobile phone and the following steps with a desktop computer.
[0092] Finally, the patient is not limited to a human being. In particular, a method of controlling the positioning of teeth according to the invention can be used for another animal.

权利要求:
Claims (11)
[0001]
REVENDICATIONS1. Acquisition kit comprising a dental retractor (10) for placement in a patient's mouth and having a registration mark (12); an image acquisition apparatus having a display screen for acquiring an image, a computer memory containing information on target acquisition conditions, a computer program comprising program code instructions for displaying, on said screen, a reference in a position such that, when the registration mark corresponds to the reference on the screen, the acquisition device meets the target acquisition conditions.
[0002]
2. Kit according to the preceding claim, wherein the acquisition apparatus is a mobile phone.
[0003]
3. Kit according to any one of the preceding claims, wherein the reference is selected from the group consisting of a point, a geometric shape, preferably a circle, a square, a rectangle or a line, a colored zone of the same color that said registration mark, a shape identical to the shape of said registration mark, a shape complementary to the shape of said registration mark, in particular to constitute a shape having a meaning, such as a geometric shape, a letter or a text, a drawing, or a pattern, and their combinations.
[0004]
4. Kit according to any one of the preceding claims, wherein the spacer comprises a plurality of non-aligned registration marks and coplanar.
[0005]
Kit according to any one of the preceding claims, wherein the registration mark is arranged so that, when it corresponds to said reference on the screen, it is less than 1 cm from an edge of the screen.
[0006]
A method of acquiring a two-dimensional image of at least a portion of the arches of a patient using an acquisition kit according to any one of the preceding claims, said method comprising the following successive steps: a) determination of target acquisition conditions according to a treatment to be applied; (b) programming the acquisition apparatus to display the reference in a position such that said mapping results in application of the target acquisition conditions; (c) placing the retractor in the patient's mouth; (d) positioning the acquisition apparatus to match the registration mark and the reference on the acquisition apparatus; (e) acquiring the image that can be acquired in the positioning of the acquisition apparatus adopted in the previous step.
[0007]
A method of controlling the positioning and / or shape of a patient's teeth, said method comprising the steps of: a) providing a digital three-dimensional reference model of at least a portion of the patient's arches, or "Initial reference model" and, optionally, for each tooth, definition, from the initial reference model, of a three-dimensional numerical reference model of said tooth, or "tooth model"; b) acquisition, by means of an acquisition kit according to any one of claims 1 to 5, preferably according to an acquisition method according to claim 6, of at least one two-dimensional image of said arches, called "image discounted "under actual acquisition conditions; c) analyzing each updated image and producing, for each updated image, an updated map relating to discriminant information; d) optionally, determining, for each updated image, coarse virtual acquisition conditions approximating said actual acquisition conditions, e) searching, for each updated image, of a final reference model corresponding to the positioning and / or the forms teeth during the acquisition of the updated image, the search being preferably carried out by means of a metaheuristic method, preferably by simulated annealing, f) for each tooth model, comparison of the positions of said tooth model in the initial reference model and in the reference model obtained at the end of the preceding steps, called the "final reference model", in order to determine the displacement and / or the deformation of the teeth between steps a) and b) and / or comparing the shapes of the initial reference model and the final reference model to determine the deformation of teeth between steps a) and b).
[0008]
The method according to the immediately preceding claim, wherein step e) comprises a first optimization operation making it possible to search for virtual acquisition conditions that best correspond to the actual acquisition conditions in a determined reference model to be tested. from the initial reference model, and - a second optimization operation for searching, by testing a plurality of said reference models to be tested, the reference model corresponding best to the positioning and / or the shape of the teeth of the patient when acquiring the updated image in step b).
[0009]
9. A method according to the immediately preceding claim, wherein a first optimization operation is performed for each test of a reference model to be tested in the second optimization operation.
[0010]
Method according to any of the two immediately preceding claims, wherein the first optimization operation and / or the second optimization operation, preferably the first optimization operation and the second optimization operation implement a metaheuristic method, preferably a simulated annealing.
[0011]
11. A method according to any one of the four immediately preceding claims, wherein step e) comprises the following steps: el) definition of the reference model to be tested as the initial reference model, then e2) according to the following steps testing virtual acquisition conditions with the reference model to be tested in order to finely approximate said actual acquisition conditions; e21) determining virtual acquisition conditions to be tested; e22) performing a two-dimensional reference image of the reference model to be tested in said virtual acquisition conditions to be tested; e23) processing the reference image to produce at least one reference map representing, at least partially, said discriminant information; e24) comparing the updated and reference maps so as to determine a value for a first evaluation function, said value for the first evaluation function depending on the differences between said updated and reference maps and corresponding to a decision to continue or stopping the search for virtual acquisition conditions approximating said actual acquisition conditions with more accuracy than said virtual acquisition conditions to be tested determined at the last occurrence of step e21); e25) if said value for the first evaluation function corresponds to a decision to continue said search, modification of the virtual acquisition conditions to be tested, then resumption in step e22); e3) determining a value for a second evaluation function, said value for the second evaluation function depending on the differences between the updated and reference maps in the virtual acquisition conditions approximating at best said actual acquisition conditions and resulting from the last occurrence of step e2), said value for the second evaluation function corresponding to a decision to continue or stop searching for a reference model approximating the positioning and / or shape of the teeth when acquiring the updated image more accurately than said reference model to be tested used at the last occurrence of step e2), and if said value for the second evaluation function corresponds to a decision to continue said search, modification of the reference model to be tested by displacement and / or deformation of one or more models of teeth then recovery in step e2).

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WO2016066652A1|2016-05-06|

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WO2016066654A1|2016-05-06|

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EP3212116A1|2017-09-06|

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EP3901906A1|2021-10-27|

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US20170325689A1|2017-11-16|

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FR3027508A1|2016-04-29|

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FR3027507B1|2016-12-23|

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EP3212114B1|2019-05-01|

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US20180185125A1|2018-07-05|

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FR3027711A1|2016-04-29|

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FR3027508B1|2016-12-23|

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WO2016066650A1|2016-05-06|

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EP3212646B1|2018-12-12|

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WO2016066651A1|2016-05-06|

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EP3213293B1|2021-09-29|

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US20170325910A1|2017-11-16|

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法律状态:
2016-03-24| PLFP| Fee payment|Year of fee payment: 2 |

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2016-04-29| PLSC| Publication of the preliminary search report|Effective date: 20160429 |

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2016-09-02| TP| Transmission of property|Owner name: H43 DEVELOPMENT S.A.R.L., LU Effective date: 20160729 |

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2017-01-13| CL| Concession to grant licences|Name of requester: H43 MANAGEMENT S.A.R.L., LU Effective date: 20161209 |

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2017-03-30| PLFP| Fee payment|Year of fee payment: 3 |

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2017-07-28| TP| Transmission of property|Owner name: DENTAL MONITORING, FR Effective date: 20170628 |

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2018-01-30| PLFP| Fee payment|Year of fee payment: 4 |

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2020-01-28| PLFP| Fee payment|Year of fee payment: 6 |

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2021-01-28| PLFP| Fee payment|Year of fee payment: 7 |

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2022-01-26| PLFP| Fee payment|Year of fee payment: 8 |

优先权:

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