Monitoring of dentition

Abstract

A method includes the following steps of (i) production with a 3D scanner, of a three-dimensional digital reference model of at least part of a dental arch of the patient, or “initial reference model”; (ii) acquisition, in actual acquisition conditions, by the patient or one of his or her close relatives, with a mobile phone, of at least three two-dimensional images of the dental arches of the patient corresponding to a front view, a right-side view and a left side view of the teeth of the patient, respectively, called “updated images”; and (iii) searching, through modification of the initial reference model, for a final reference model corresponding to the positioning and/or the shape of the teeth on the updated images.

1 . A method comprising the following steps:
 production with a 3D scanner, of a three-dimensional digital reference model of at least part of a dental arch of the patient, or “initial reference model”;   acquisition, in actual acquisition conditions, by the patient or one of his or her close relatives, with a mobile phone, of at least three two-dimensional images of the dental arches of the patient corresponding to a front view, a right-side view and a left side view of the teeth of the patient, respectively, called “updated images”;   searching, through modification of the initial reference model, for a final reference model corresponding to the positioning and/or the shape of the teeth on the updated images.   
     
     
         2 . The method according to  claim 1 , in which at least one of said updated images is acquired in mouth closed position and/or at least one updated image is acquired in mouth open position. 
     
     
         3 . The method according to  claim 1 , in which the updated images are photographs or are extracted from a film. 
     
     
         4 . The method according to  claim 1 , in which the updated images are a panoramic photograph. 
     
     
         5 . The method according to  claim 1 , in which the mobile phone is not immobilized, and the head of the patient is not immobilized. 
     
     
         6 . The method according to  claim 1 , in which, in order to improve the visibility of the teeth during the acquisition of the updated images, the lips of the patient are separated with a separator. 
     
     
         7 . The method according to  claim 6 , in which the separator comprises a support provided with a rim extending around an aperture and arranged such that the lips of the patient may rest thereon leaving the teeth of the patient showing through said aperture and/or comprising independent left and right parts. 
     
     
         8 . The method according to  claim 1 , in which at least one of said updated images is acquired in mouth closed position and at least one updated image is acquired in mouth open position, and in which, in order to improve the visibility of the teeth during the acquisition of the updated images, the lips of the patient are separated with a separator comprising a support provided with a rim extending around an aperture and arranged such that the lips of the patient may rest thereon leaving the teeth of the patient showing through said aperture. 
     
     
         9 . The method according to  claim 1 , in which the updated images are acquired at an instant determined by the patient. 
     
     
         10 . The method according to  claim 1 , in which at least one reminder informing the patient of the need to create updated images is addressed to the patient. 
     
     
         11 . The method according to  claim 1 , in which the updated images are acquired less than 7 days after the production of the initial reference model, to detect any difference between the initial and final reference models. 
     
     
         12 . The method according to  claim 1 , in which the updated images are acquired before the creation of the initial reference model. 
     
     
         13 . The method according to  claim 1 , in which the time interval between the production of the initial reference model and the acquisition of the updated images is determined by an orthodontist, according to a monitoring schedule. 
     
     
         14 . The method according to  claim 1 , in which the time interval between the production of the initial reference model and the acquisition of the updated images is greater than one week. 
     
     
         15 . The method according to  claim 1 , in which the production of the initial reference model is less than three months after the start of an orthodontic treatment. 
     
     
         16 . The method according to  claim 1 , in which the production of the initial reference model is at a start of an othodontic treatment. 
     
     
         17 . The method according to  claim 1 , in which the production of the initial reference model is less than three months after an end of an othodontic treatment. 
     
     
         18 . The method according to  claim 1 , in which the initial reference model is prepared independently of any treatment for the patient to monitor the movements of his or her teeth. 
     
     
         19 . The method according to  claim 1 , in which, the initial reference model is modified for said three-dimensional digital final reference model to best correspond to the updated images. 
     
     
         20 . The method according to  claim 19 , in which said modification comprises a first optimization operation making it possible to search the virtual acquisition conditions best corresponding to said 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, for the reference model best corresponding to the positioning and/or the shape of the teeth of the patient during the acquisition of the updated images. 
     
     
         21 . The method according to  claim 20 , in which a said first optimization operation is performed for each test of a reference model to be tested during a said second optimization operation. 
     
     
         22 . The method according to  claim 20 , in which the first optimization operation and/or the second optimization operation implement a metaheuristic method. 
     
     
         23 . The method according to  claim 22 , in which, said metaheuristic method is evolutionist. 
     
     
         24 . The method according to  claim 22 , in which the first optimization operation and/or the second optimization operation implement simulated annealing. 
     
     
         25 . The method according to  claim 1 , in which a three-dimensional digital reference model is defined for each tooth of the initial reference model, or “tooth model”. 
     
     
         26 . The method according to  claim 25 , in which, said modification of the initial reference model comprises movements of one or more tooth models and/or deformation of one or more tooth models. 
     
     
         27 . The method according to  claim 26 , in which, said modification of the initial reference model is performed by means of a metaheuristic method. 
     
     
         28 . The method according to  claim 1 , in which the initial reference model is not segmented into tooth models, and in which the final reference model is compared to the initial reference model to detect an addition or a subtraction of material to the teeth and/or a deformation of the teeth with constant volume, and/or to detect movements of the teeth. 
     
     
         29 . The method according to  claim 1 , in which the modification of the initial reference model comprises:
 an analysis of each updated image, and a production, for each updated image, of an updated map relating to a discriminating piece of information,   an analysis of a view of the initial reference model, and a production of a reference map relating to said discriminating piece of information, and   a modification of the initial reference model depending on the difference between the updated map and the reference map.   
     
     
         30 . The method according to  claim 29 , in which the discriminating piece of information is chosen from the group consisting of a piece of outline information, a piece of color information, a piece of density information, a piece of distance information, a piece of brightness information, a piece of saturation information, an information on glare and combinations of the above pieces of information. 
     
     
         31 . The method according to  claim 29 , in which the searching for the final reference model comprises the following steps:
 e1) definition of a reference model to be tested as being the initial reference model then,   e2) according to the following steps, testing of the virtual acquisition conditions with the reference model to be tested in order to finely approximate said actual acquisition conditions;
 e21) determination of virtual acquisition conditions to be tested; 
 e21) production of a two-dimensional reference image of the reference model to be tested in said virtual acquisition conditions to be tested; 
 e22) processing of the reference image to produce at least one reference map representing, at least partially, said discriminating piece of information; 
 e23) comparison of the updated and reference maps so as to determine a value for a first assessment function, said value for the first assessment function depending on the differences between said updated and reference maps and corresponding to a decision to continue or to stop the search for virtual acquisition conditions approximating said actual acquisition conditions with greater accuracy than said virtual acquisition conditions to be tested determined on the last occurrence of the step e21); 
 e24) if said value for the first assessment function corresponds to a decision to continue said search, modification of the virtual acquisition conditions to be tested, then return to the step e22); 
   e3) determination of a value for a second assessment function, said value for the second assessment function depending on the differences between the updated and reference maps in the virtual acquisition conditions best approximating said actual acquisition conditions and resulting from the last occurrence of the step e2), said value for the second assessment function corresponding to a decision to continue or to stop the search for a reference model approximating the shape and/or the positioning of the teeth during the acquisition of the updated image with greater accuracy than said reference model to be tested used on the last occurrence of the step e2), and if said value for the second assessment 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 movement and/or deformation of one or more tooth models, then return to the step e2).   
     
     
         32 . The method according to  claim 1 , in which the shapes of the initial reference model and of the final reference model are compared. 
     
     
         33 . The method according to  claim 32 , in which said comparison is used for displaying and/or measuring and/or detecting a dental plaque, and/or a start of caries, and/or a microcracking, and/or wear of teeth, and/or stripping or for displaying and/or measuring and/or detecting a change of volume, or for assessing the benefit of an orthodontic treatment. 
     
     
         34 . The method according to  claim 32 , in which the updated images are acquired after a time interval after the production of the initial reference model, said time interval depending on the results of a comparison obtained following an earlier execution of a method according to  claim 32 . 
     
     
         35 . The method according to  claim 32 , in which the updated images are acquired at determined at an instant determined according to a monitoring schedule drawn up by an orthodontist. 
     
     
         36 . The method according to  claim 32 , in which an effectiveness of an orthodontic treatment is measured from results of said comparison.