EP2879585A1

EP2879585A1 - Method and device for preparing the fitting of a dental implant

Info

Publication number: EP2879585A1
Application number: EP13733340.7A
Authority: EP
Inventors: Guillaume Champleboux
Original assignee: 3DKreaform (Societe par actions simplifiee)
Current assignee: 3DKreaform (Societe par actions simplifiee)
Priority date: 2012-07-31
Filing date: 2013-06-04
Publication date: 2015-06-10
Also published as: US20150196372A1; CA2880281A1; FR2994076A1; BR112015001819A2; RU2015106983A; FR2994076B1; JP2015527129A; WO2014020247A1; CN104684484A

Abstract

The invention relates to a method of preparing the fitting of at least one dental implant, comprising the linking of a first three-dimensional model of the external surface of at least a part of the buccal cavity of a patient or of a reproduction made of a solid material of said at least one part of the buccal cavity and of a second three-dimensional model of at least a part of the bone system of the jaw of the patient on the basis of the recognition of faces of a benchmark element in the first model and of at least one portion of the benchmark element in the second model.

Description

METHOD AND DEVICE FOR PREPARING THE INSTALLATION OF AN IMPLANT

DENTAL

Field of the invention

The present invention relates to the placement of dental implants intended to ensure the maintenance of prostheses.

State of the art

When the dentition of a patient is severely degraded, we can consider replacing the missing teeth with dentures. The prosthesis can be anchored in the upper or lower jaw of the patient via an implant or multiple implants screwed into the jaw. The installation of an implant therefore requires drilling a hole in the jaw, the implant then being screwed into this hole.

A difficulty lies in the fact that, when the dentition of a patient is severely degraded, it also often happens that the bone system of his jaws is also in poor condition. The locations where implants can be placed are therefore severely limited and must be determined with great precision.

A conventional method of assisting the placement of implants comprises the realization of a transparent resin channel, also called radiological guide, which is the negative reproduction of the jaw of the patient. The realization of the gutter usually requires taking a physical imprint of the jaw to implant, casting a plaster copy from this impression, a prosthetic study by a practitioner during which there may be the establishment of false radiopaque teeth or radiopaque marks on the plaster copy and elaboration of the gutter from the plaster copy containing false teeth or radiopaque marks. False teeth or radio-opaque marks indicate the desired positions of the hole drilling axes for screwing the implants. It is then verified that these positions are compatible with the bone system of the jaw. For this purpose, images of the bone system are obtained, for example, by tomodensitometry while the patient has the gutter in the mouth. Once the implant positions are precisely defined, the cylin ^¬ driques apertures can be drilled in the channel for the introduction of metal tubes. These tubes guide the tool with which the holes are pierced in the jaw during the placement of the implants. The gutter thus modified is called a drilling guide or surgical guide.

The determination of the real positions using images of the bone system is done more or less empirically by the practitioner by looking at images of the bone system taken when the patient has the mouth in the mouth. This is a delicate operation that requires great experience on the part of the practitioner. In addition, it can be difficult to determine the position of the implants accurately.

It would be desirable to assist the practitioner when determining the actual positions of the implants. In addition, it would be desirable for implant positions to be accurately determinable.

The method of preparation for implant placement is a long process. Indeed, it requires taking the impression of the jaw of the patient, the realization of the plaster copy, the realization of the gutter from the plaster copy and finally the acquisition of images by X-ray scanner while the patient has the gutter in the mouth. To achieve the drilling guide, it is further necessary to machine the gutter in accordance with the definition of the position of the implants as positioned virtually using CT images. In addition, the method is restrictive for the patient since it is necessary for the patient to be present for the first time to take the impression of his jaw a second time, after completion of the gutter, for the acquisition of the images. in the scanner and finally a third time the day of the surgery. It would be desirable to reduce the duration of the preparation process for the implantation of a dental implant and to require a smaller number of times the presence of the patient.

summary

Thus, an embodiment of the present invention aims to overcome at least in part the disadvantages of the implant preparation methods described above.

The present invention aims at providing a dental implant preparation method which facilitates and improves the accuracy of the determination of the position of the implants.

Another object of an embodiment of the present invention is that a surgical guide may be made by a computer aided manufacturing tool.

Another object of an embodiment of the present invention is that taking a physical impression of the patient's jaw is not necessary.

Another object of an embodiment of the present invention is that the method of preparation requires the presence of the patient only once.

For this purpose, one aspect of an embodiment of the invention provides a method of preparing for the installation of at least one dental implant, comprising the following steps: attaching at least one registration element to at least a portion of the oral cavity of a patient;

acquisition, by an optical sensor or a probe, of data relating to said at least part of the oral cavity;

providing a first three-dimensional model of the outer surface of said at least a portion of the oral cavity from data relating to said at least a portion of the oral cavity;

acquiring, by an X-ray scanner, data relating to at least a part of the bone system of the patient's jaw;

providing a second three-dimensional model of said at least a portion of the bone system of the patient's jaw from data relating to said at least a portion of the bone system of the jaw;

computer recognition of faces of said at least one registration element in the first model;

computer determination of a first three-dimensional coordinate system associated with the first model;

computer recognition of at least a portion of said at least one registration element in the second model;

computer determination of a second three-dimensional coordinate system associated with the second model;

computer determination of a passing relation between the first coordinate system and the second coordinate system from said faces and said portion; and determining the position of said implant from the first model and the second model and from the first coordinate system, the second coordinate system and the transit relationship.

According to an embodiment of the present invention, the step of determining the position of said implant from the first model and the second model and from the first coordinate system and the second coordinate system comprises the following steps:

determining the position of a dental prosthesis associated with said implant in the first model;

determining the theoretical position of the implant in the second model from the position of the associated dental prosthesis in the first model; and

determining the ideal position of the implant in the second model from the theoretical position.

According to an embodiment of the present invention, the method further comprises the following steps:

attaching an additional registration element to another portion of the oral cavity opposite to said portion;

acquisition, by the optical sensor or the probe, of data relating to the said other part of the oral cavity;

providing a three-dimensional model of the outer surface of said other portion of the oral cavity from data relating to said other portion of the oral cavity;

acquiring, by the optical sensor or the probe, data relating to the marker element and to the supplementary marker element when the mouth is in occlusion; and providing a three-dimensional model of the outer surface of the registration element and the additional registration element when the mouth is occluded.

According to one embodiment of the present invention, the step of determining the position of said implant is performed from the first model and the three-dimensional model of the outer surface of said other part of the oral cavity placed in occlusion.

According to one embodiment of the present invention, a denture is capable of being placed on said part of the oral cavity, the first model being determined in the absence of the denture, the method further comprising the following steps: placing the denture on said part of the oral cavity;

acquisition by the optical sensor or the probe of data relating to the denture; and

providing a three-dimensional model of the outer surface of the denture from the denture data.

According to an embodiment of the present invention, the method further comprises determining the drilling axis of said implant, the determination of a three-dimensional model of a gutter comprising a cylindrical opening along the axis of drilling said implant and computer-aided manufacturing said gutter comprising said opening.

According to an embodiment of the present invention, the step of determining the second coordinate system comprises determining the inertia matrix of said portion.

attaching at least three registration elements to said portion of the oral cavity of a patient;

computer recognition of faces of each registration element in the first model;

computer determination, for each registration element, of a first reference point in the first model;

computer recognition of at least a portion of each registration element in the second model;

computer determination, for each registration element, of a second reference point in the second model; and

computer determination of the passage relationship between the first coordinate system and the second coordinate system from the first three reference points and the three second reference points. Another aspect of an embodiment of the present invention provides a dental implant preparation system, the system comprising:

at least one registration element comprising at least three non-parallel faces visible by an optical camera and / or a probe and at least one X-ray localizable portion, said registration element being adapted to be fixed to at least a part of the cavity oral of a patient;

an optical image sensor or a probe adapted to acquire data relating to said at least part of the oral cavity;

an X-ray scanner adapted to acquire data relating to at least a portion of the bone system of the patient's jaw; and

a processing module connected to the X-ray scanner and the optical image sensor and / or the probe, the processing module, the optical image sensor and / or the X-ray scanner being adapted to provide a first three-dimensional model of the outer surface of said at least a portion of the oral cavity from data relating to said at least a portion of the oral cavity, providing a second three-dimensional model of said at least a portion of the bone system of the patient's jaw from data relating to said at least part of the bone system of the jaw, recognizing the faces in the first model, determining a first three-dimensional coordinate system associated with the first model, recognizing said at least one portion in the second model, determining a second coordinate system associated with the second model, determine a transition relationship between the first coordinate system and the second coordinate system from said faces and said portion, and determining the position of said implant from the first model and the second model and from the first three-dimensional coordinate system, the second coordinate system and the passage relationship. According to an embodiment of the present invention, said faces are made of an X-ray transparent material.

According to one embodiment of the present invention, the X-ray transparent material is, in addition, opaque to visible light.

According to an embodiment of the present invention, said portion corresponds to an insert.

According to one embodiment of the present invention, at least two faces of said three faces are flat and inclined with respect to one another by an angle of preferably between 5 ° and 85 ° or between 95 ° and 270 ° °.

According to one embodiment of the present invention, at least one of the faces corresponds to a sphere portion or to a cylinder portion.

According to one embodiment of the present invention, said portion is covered by said faces.

According to one embodiment of the present invention, said portion comprises at least two rectilinear and non-concurrent tubes.

According to an embodiment of the present invention, said portion comprises at least three spheres whose centers are not aligned.

According to one embodiment of the present invention, the spheres have different diameters.

According to one embodiment of the present invention, said portion comprises at least one parallelepiped.

According to one embodiment of the present invention, the registration element comprises at least first, second and third non-parallel flat faces, at least the first face being inclined with respect to the second face by an angle preferably comprised between 5 ° and 85 ° or between 95 ° and 270 ° and the first face being inclined relative to the third face by an angle preferably between 5 ° and 85 ° or between 95 ° and 270 °. Another aspect of an embodiment of the present invention provides a dental implant preparation system for carrying out the method as defined above, the system comprising:

a registration element as defined above; an optical image sensor and / or a probe; an X-ray scanner; and

a processing module connected to the X-ray scanner and the optical image sensor and / or the probe.

Brief description of the drawings

These and other objects, features, and advantages will be set forth in detail in the following description of particular embodiments in a non-limitative manner with reference to the accompanying figures in which:

Figures 1 and 2 are schematic perspective views of an embodiment of a registration element according to the invention;

Figures 3 to 11 are schematic perspective views of other embodiments of the registration element according to the invention;

Figure 12 shows the registration element of Figure 1 glued to a tooth of a patient;

Figure 13 shows the registration element of Figure 11 attached to the jaw of a patient;

FIG. 14 is a fragmentary and diagrammatic representation of an embodiment according to the invention of a preparation system for implant placement;

FIG. 15 illustrates, in the form of a block diagram, an embodiment according to the invention of a preparation method for implant placement;

FIG. 16 illustrates, in the form of a block diagram, a variant of the embodiment according to the invention of the method of preparation for implant placement illustrated in FIG. 15; and FIG. 17 illustrates, in the form of a block diagram, another variant of the embodiment according to the invention of FIG. implant preparation method illustrated in Figure 15.

For the sake of clarity, the same elements have been designated by the same references in the various figures and, in addition, the various figures are not drawn to scale.

detailed description

Unless otherwise indicated, in the remainder of the description, the expressions "about", "substantially" and "of the order of" mean "at about 10 ~ 6".

A known method for preparing implant placement comprises the following succession of steps:

(1) Making an impression of the jaw to be implanted using an impression material such as silicone, an alginate, a hydrocoloid, etc.

(2) Casting a plaster copy from this impression.

(3) Estimation by the practitioner, from the impression, of the ideal positions of the prostheses.

(4) Realization of a transparent resin gutter from the plaster copy. This resin gutter contains either radio-opaque false teeth or radiopaque marks, for example cylinders or cones, in an X-ray visible material such as gutta-percha, which represent the desired positions of the axes of the associated implants. at the ideal positions of the prostheses. The gutter is the negative reproduction of this copy on which it must be able to fit intimately. All the faces of the gutter that do not come into contact with the plaster copy have any shape. The gutter with false radiopaque teeth or radiopaque marks is called a radiological guide. It is then necessary to determine if these estimated axes of drilling, which are ideal from the prosthetic point of view, are compatible with the bone structure of the jaw.

(5) Performing an X-ray scan of the patient with the X-ray guide in the mouth. (6) Determination by the practitioner, from the image of the radiopaque marks, if each implant can be placed at the desired location respecting the various endo-osseous elements and according to what approximate trajectory. If the implant can not be placed at the desired location, the practitioner estimates moving to another position relative to the mark included in the radiological guide.

(7) Possibly, piercing the gutter which will then serve as a surgical guide for piercing the jaw at the location where it is desired to insert the implant.

The principle of the invention is to determine the position of the implants by using both a three-dimensional modeling of the teeth and the bone structure of the patient's jaw in which the soft tissues, in particular the gums, are not represented (or any at least are not sufficiently identifiable), and a modeling tridimension ^¬ nelle from inside the patient's mouth, obtained direc ^¬ or indirectly, wherein the surface of the soft tissue, especially the gums and the tooth surface existing, are represented.

Three-dimensional modeling of the bone structure can be obtained by computed tomography from images provided by an X-ray scanner. The three-dimensional model of the bone structure and teeth is subsequently called an internal three-dimensional model.

The three-dimensional surface modeling of the inside of the patient's mouth can be obtained from images provided by an intraoral sensor, for example an optical camera, adapted to be introduced into the patient's mouth or from images. (in particular in the form of a three-dimensional point cloud) provided by a three-dimensional optical surface sensor or a three-dimensional probe using a reproduction in solid material of the portion of the oral cavity to be modeled, in particular when the practitioner does not have intra-oral camera. The three-dimensional model the outer surface of the soft tissues (especially the gums) and teeth of a patient's mouth is subsequently referred to as an external three-dimensional model.

The joint use of the internal three-dimensional model and the external three-dimensional model allows the practitioner to place the implants with greater ease and precision. In particular, the soft tissues can be represented, for example, superimposed on the bone system of the jaw on the same display device.

In addition, when a surgical guide is to be performed, a three-dimensional model of the entire outer surface of the surgical guide can be determined. The surgical guide can then be produced by computer-aided manufacturing tools.

In addition, when the external three-dimensional model is determined using an intraoral camera inserted into the patient's mouth, steps (1) to (4) of the implant preparation method previously described and leading to the realization of of a radiological guide are no longer necessary. The duration of the preparation process for implant placement can be reduced.

The position of the implants is determined by the linking of the external three-dimensional model which contains precise and distinct information assisting the position of the prostheses and the internal three-dimensional model which contains information relating to the bone structure of the jaw. The positioning of the implants and the linking of the external and internal three-dimensional models are performed using a computer.

According to one embodiment of the present invention, the linking of the external three-dimensional model and the internal three-dimensional model is achieved by using a tracking element present in the patient's mouth during the acquisition of the images used to determine the three-dimensional model. external and the internal three-dimensional model and which is at least partially visible both on the external three-dimensional model and on the internal three-dimensional model.

Figures 1 and 2 show, schematically, two perspective views of an embodiment of a registration element 1 according to the invention. The registration element 1 comprises a block 2 having the general shape of a central rectangular parallelepiped comprising two opposite ends extending by a truncated pyramid. The block 2 has a height H of between 5 mm and 50 mm, a length _T] _ of between 5 mm and 50 mm and a width L2 between 4 mm and 40 mm.

Block 2 comprises a front face 4, a rear face 6, two side faces 8, 10. The front 4 and rear 6 faces are flat and parallel and the side faces 8 and 10 are flat, parallel to each other and perpendicular to the faces 4 , 6.

At a first end, the registration element 1 comprises three external registration faces 12, 14, 16 which are used to recognize the registration element 1 in the external three-dimensional model. The registration faces 12, 14 and 16 of the registration element 1 are made of a material that is substantially opaque to visible light, so as to be visible on images obtained by an optical image acquisition device. It is, moreover, a material which does not produce artifacts on images acquired by an optical camera as well as on tomodensitometric images obtained by an X-ray scanner. By way of example, it is is polyetheretherketone (or PEEK), or polyoxymethylene (or POM). In addition, it is a material compatible with the establishment of the marker element 1 temporarily in the mouth of a patient.

In the present embodiment, the registration faces 12, 14, 16 are non-parallel planar faces. Preferably, the faces 12 and 14 have a common edge 18, the faces 12 and 16 have a common edge 20 and faces 14 and 16 have a common edge 22. Preferably, the three edges 18, 20 and 22 meet at a point 0. Alternatively, the faces 12 and 14 may be connected to one another in a rounded portion. It may be the same for the faces 12 and 16 and / or for the faces 14 and 16.

In the embodiment shown in Figure 1, the face 14 is inclined relative to the face 12 by an angle of about 45 °. The face 16 is inclined relative to the face 12 by an angle of about 45 ° and the face 16 is inclined relative to the face 14 by an angle of about 45 °.

In general, the face 12 is inclined with respect to the face 16 by an angle which can preferably vary from 5 ° to 270 °, preferably from 5 ° to 85 ° or from 95 ° to 270 °. The face 14 is inclined relative to the face 16 by an angle which can preferably vary from 5 to 270 °. The face 12 is inclined with respect to the face 14 by an angle which can preferably vary from 5 ° to 85 ° or from 95 ° to 270 °.

As can be seen in FIG. 2, the registration element 1 comprises a protuberance 26, having a face 28, preferably plane, which projects from the face 6. As a variant, the protuberance 26 is not present. In operation, the registration element 1 is intended to be placed temporarily in the mouth of a patient. For this purpose, the face 28 of the registration element 1 may be temporarily bonded to a tooth or the gingiva of the patient.

The registration element 1 comprises, in addition to the registration faces 12, 14 and 16, additional registration faces 34, 36, 38. By way of example, the faces 34, 36, 38 correspond to the symmetries of the faces 12, 14, 16 with respect to a plane of symmetry. In general, the face 34 is inclined relative to the face 38 by an angle which can preferably vary from 5 ° to 90 °. The face 36 is inclined with respect to the face 38 by an angle which can preferably vary from 5 ° to 90 ° or from 95 ° to 270 °. The face 34 is inclined relative to the face 36 an angle which can preferably vary from 5 ° to 90 ° or from 95 ° to 270 °.

The registration element 1 comprises one or more radiopaque inserts 30. By radio-opaque inserts is meant an insert substantially opaque to X-rays.

A feature of the insert or radiopaque inserts is that they are in an X-ray visible material to be locatable by a scanner. The insert or the radiopaque inserts are chosen from a material that does not produce artifacts when it is scanned, including a scanner trace (which corresponds, for example, to the images supplied by the scanner to pixels of which the gray level is more or less important) is sufficiently contrasted with respect to tissues and bones and has sufficient mechanical strength. The insert or radiopaque inserts are for example made of titanium or aluminum.

Preferably, the whole of the registration element 1, except for the radiopaque insert or inserts, is made of a material which is substantially transparent to X-rays. Therefore, during the acquisition of an image provided by a scanner, only the insert or the radiopaque inserts of the registration element 1 appear clearly on the image. In particular, the registration faces 12, 14 and 16 do not substantially appear in the internal three-dimensional model. In the present embodiment, the radiopaque insert 30 is housed in an aperture 32 provided in the registration element 1. Alternatively, the opaque light-sensitive material may be overmolded onto the insert or radio-opaque inserts.

Alternatively, for some embodiments, the entire registration element may be of radio-opaque material. In this case, the faces 12, 14, 16 are made of material substantially opaque to X-rays.

In the embodiment shown in FIG. 1, the radio-opaque insert comprises a parallelepiped 30 of radiopaque material housed in an opening 32 which opens on the face 6 of the tracking element 1. To facilitate understanding of the present invention, 1 insert 30 is repre ^¬ sented in solid lines in Figure 1 when it is in fact hidden by block 2. It may be a rectangular parallelepiped. By way of example, the radio-opaque insert of the registration element 1 comprises only the parallelepiped 30.

Figure 3 shows a registration element 40 according to another embodiment of the invention. The registration element 40 differs from the registration element 1 in that the parallelepiped radiopaque insert 30 is replaced by three spheres 42, 44 and 46 in a radiopaque material and, for example, embedded in the mass. of the registration element 40. To facilitate the understanding of the present invention, the spheres 42, 44 and 46 are shown in solid lines in FIG. 3 whereas they are, in reality, hidden by the block 2. The centers of the spheres 42, 44 and 46 are not aligned. Preferably, the diameters of the spheres are different. The diameter of the sphere 44 may be strictly smaller than the diameter of the sphere 42 and the diameter of the sphere 46 may be strictly smaller than the diameter of the sphere 44. By way of example, the radiopaque inserts of the element of FIG. locating 40 include only the three spheres 42, 44 and 46.

Figure 4 shows a registration element 50 according to another embodiment of the invention. The registration element 50 differs from the registration element 1 in that the parallelepiped radiopaque insert 30 is replaced by two radiopaque tubes 52, 54. For example, the tubes 52, 54 are embedded in the mass of the block 2, but, to facilitate the understanding of the present invention, are nevertheless represented in solid lines in FIG. 4. The two tubes 52, 54 may be tubes 52, 54 full and rectilinear, whose respective axes are, for example, contained in two planes parallel to each other and substantially perpendicular to the occlusion plane when the locating element 50 is placed in the mouth of the patient. The tubes 52 and 54 are, for example, drowned in the material constituting the body 2 of the locating element 50 during its manufacturing process.

The axes of the tubes 52 and 54 are not parallel to each other and are, for example, an angle of between 30 and 120 °, preferably 90 °. As described in more detail below, the role of the tubes 52 and 54 is to define two non-concurrent lines in reconstructed images from scanner tomographic sections.

Note that the tubes 52 and 54 are such that their respective axis is not concurrent. However, the embodiment as shown in FIG. 4, in which the axes of the tubes 52 and 54 are in parallel planes, constitutes a preferred arrangement of the tubes 52 and 54 insofar as it minimizes the bulk of the element. locating means 50 so as to allow placement of the locating element 50 in the mouth of a patient.

FIG. 5 represents a locating element 60 corresponding to a variant of the registration element 1 represented in FIG. 1 in which the registration faces 34, 36 and 38 are not present.

Figures 6 and 7 show two perspective views of a registration element 70 according to another embodiment of the invention. The registration element 70 differs from the registration element 1 in that the faces 16 (and 38) and 6 are merged and in that the face 14 (and 36) is replaced by a face 72 corresponding to one half. cylinder. Preferably, the faces 12 and 72 have a common edge 74 corresponding to a semicircle and the faces 12 and 16 have a common edge 20 ^¬ corres ponding to a line segment. The registration element 70 further comprises the tubes 52, 54 (only the tube 54 being visible in FIG. 7) of a radiopaque material housed in an opening 78.

Figures 8 and 9 show two views in pers ^¬ pective a registration element 80 according to another embodiment of the invention. The registration element 80 differs from the registration element 1 in that the faces 16 (and 38) and 6 are combined, in that the face 12 is replaced by a face 82 corresponding to a quarter of a sphere and in that the face 14 is replaced by a face 84 (and 36) corresponding to a half-cylinder. Preferably, the faces 82 and 84 have a common edge 86 corresponding to a semicircle and the faces 82 and 16 have a common edge 88 corresponding to a semicircle. In addition, the registration face 36 is replaced by the face 89 which corresponds to the symmetrical face 82 relative to a plane of symmetry and corresponds to a quarter sphere. Preferably, the faces 89 and 84 have a common edge 90 corresponding to a half-circle and the faces 89 and 16 have a common edge 92 corresponding to a semicircle. The registration element 80 further comprises the spheres 42, 44 and 46 (only the spheres 42 and 44 being visible in Figure 9) of a radiopaque material housed in openings 94, 96, 98.

Figure 10 shows a registration element 81 corresponding to a variant of the registration element 60 in which a fastening element 83 is provided on the rear face of the registration element 81. The fastening element 83 comprises suction cups 85 By way of example, new suction cups 85 are shown in FIG. 10. The fixing element 83 is preferably made of a material that is substantially transparent to X-rays. The suction cups 85 for fixing the tracking element 81 in the oral cavity of a patient without the use of glue or adhesive material. The fastener 83 may be provided with all the registration element embodiments described above in connection with FIGS. 1-9.

FIG. 11 shows a marking device 91 which comprises three unitary registration elements which may each correspond to one of the identification elements described above in relation with FIGS. 1 to 10. By way of example, in FIG. locating device 91 comprises the registration element 81 shown in FIG. copies. One of the unitary registration elements 81 may be connected by a flexible wire 93 to each of the other two unitary registration elements. The wires 93 are preferably made of a material that does not create artifacts on the X-ray images. The wires 93 are, for example, made of titanium.

Figure 12 shows, partially and schematically, the oral cavity 100 of a patient. There are shown teeth 102, tongue 104 and gingiva 106 of a patient. As described in more detail below, during the implementation of the implant preparation method according to the invention, the registration element 1 shown in FIG. 1 is attached to a tooth 102 at the level of the implant. of the face 28 of the protrusion 26. By way of example, the element 1 can be glued to a tooth 102 or to the gum 106 by means of an adhesive or an adhesive material which allows temporary gluing . The glue is, for example, based on stone paste. Preferably, the registration element 1 is glued so that the three faces 12, 14 and 16 described above are easily visible on images acquired by an optical camera moved in the mouth of the patient by a practitioner. Preferably, the registration face 12 is placed substantially parallel to the occlusion plane in the patient's mouth. Preferably, one insert or radiopaque inserts 30 are placed sensi ^¬ ably below the line tooth 102 / gum 106 so that the artifacts may be created by metal parts, such as dental amalgams or bridges , do not affect the detection of radiopaque markers on CT images provided by the X-ray scanner.

Figure 13 shows, partially and schematically, the oral cavity 100 of Figure 12 in which the locating device 91 of Figure 11 has been attached. Each unit marking element 81 of the marking device 91 is attached to a tooth 102 or to the gum 106 by means of the suction cups 85. As a variant, the marking elements The units of the tracking device 91 can be attached to the teeth 102 or the gum 106 by means of an adhesive or an adhesive material which allows temporary bonding. The positioning of each unitary registration element 81 may follow the conditions described above in connection with FIG. 12. Advantageously, a unitary registration element 81 is fixed on each lateral portion of the jaw, the third unitary identification element 81 being able to be fixed in front of the jaw.

FIG. 14 is a fragmentary and diagrammatic representation of an embodiment according to the invention of a system 110 for the preparation of implants. The system 110 comprises a processing module 112 (μΡ) connected to a human-machine interface (HMI) 114, to an optical and / or tactile analysis module 116 and to an X-ray analysis module 118. processing 112 may further be connected to a computer-assisted manufacturing module 120 (CAM). The processing module 112 may correspond to a computer, comprising for example at least one microcontroller and a memory. The human-machine interface 114 may comprise a display screen, possibly a touch screen, a keyboard, a mouse, etc. The system 110 further comprises a registration element 1. Alternatively, the registration element may correspond to any of the previously identified registration elements 40, 50, 60, 70, 80 or 81 or locating device 91 described above.

The processing module 112 is adapted to link the external three-dimensional model and sorting model ^¬ internal dimensional.

According to one embodiment of the invention, the optical and / or tactile analysis module 116 comprises an intra-oral optical camera adapted to acquire images in the oral cavity of a patient. According to another embodiment of the invention, the analysis module 116 comprises an optical camera or a three-dimensional probe suitable for making the acquisition of images of objects outside the oral cavity. The analysis module 116 is adapted to transmit the images obtained to the processing module 112. The processing module 112 is adapted to determine the external three-dimensional model from the images provided by the analysis module 116.

According to one embodiment of the invention, the X-ray analysis module 118 comprises a scanner adapted to acquire X-ray images of the oral cavity of a patient. The X-ray analysis module 118 is adapted to transmit the images obtained to the processing module 112. The processing module 112 is adapted to determine the internal three-dimensional model from the images provided by the X-ray analysis module. .

According to one embodiment of the invention, the optical analysis module 116 comprises an apparatus for supplying an external three-dimensional model of the patient's oral cavity, for example the apparatus marketed by the company "3M ESPE" under the denomination "Intraoral scanner lava SOS". According to another embodiment of the invention, the analysis module 116 includes a supply of a model tridimen apparatus ^¬ external dimensional object, for example the apparatus marketed by the company under the Straumann Etkon 3D denomination uses a video camera or the apparatus marketed by Renishaw under the name Scanner Piccolo which implements a 3-axis mechanical probe. The analysis module 116 is adapted to transmit the external three-dimensional model to the processing module 112.

According to one embodiment of the invention, the analysis module 118 comprises an X-ray tomography apparatus, for example a CTCB (acronym for Cone Beam Computerized Tomography). The module 118 is adapted to determine the internal three-dimensional model of the patient's oral cavity and to transmit the internal three-dimensional model to the treatment module 112. FIG. 15 represents a block diagram illustrating an embodiment of a method for preparing dental implant placement according to the invention that can be implemented with the system 110 described in FIG. 14 and in particular with n ' any of the previously-identified registration elements 1, 40, 50, 60, 70, 80, 81 or with the registration device 91.

In step 122, the dentist places the registration element 1 or the tracking device 91 in the mouth of a patient. The registration element 1 or the marking device 91 may be fixed temporarily, for example by means of an adhesive, to a tooth 102 or several teeth 102 as shown in FIG. 12 or 13 or FIG. the gum 106 of the patient. When the registration element corresponds to the registration element 81, the registration element 81 can be attached to a tooth 102 or to the gum 106 of the patient via the suction cups 85. The registration element 1 or the locating device 91 is then fixed relative to the lower or upper jaw of the patient for at least the duration of the following steps 124 and 126. The process continues at step 124.

In step 124, the external three-dimensional model is determined, while the registration element 1 or the tracking device 91 is present in the patient's mouth. The external three-dimensional model can be determined by the processing module 112 from the images provided by the camera 116. For this purpose, the practitioner at least partially inserts the camera 116 into the patient's mouth and acquires images of the patient. the outer surface of the teeth 102, gums 106, and the registration element 1 or the tracking device 91, the camera 116 being moved into the mouth of the patient during the acquisition of the images. As a variant, the external three-dimensional model can be determined by the optical analysis module 116. The external three-dimensional model corresponds, for example, to a point file or to an STL file (STEREOLithography) which is a format frequently used by stereolithography software. A powder may optionally be distributed in the patient's mouth to reduce the appearance of artifacts on the images acquired by the camera 116. The process continues in step 126.

In step 126, the internal three-dimensional model is determined while the registration element 1 or the tracking device 91 is present in the patient's mouth. The internal three-dimensional model can be obtained by X-ray tomography. Data, for example two-dimensional images, can be provided by the X-ray scanner 118 and the internal three-dimensional model can be determined by the processing module 112 from of these data by a tomographic reconstruction algorithm. Two-dimensional images can be in DICOM format (Digital Imaging and Communications in Medicine). By way of example, a set of two-dimensional images is obtained according to regularly distributed cutting planes (for example an image every millimeter), each image having substantially the same number of pixels distributed in a regular manner. The internal three-dimensional model then corresponds to a volumetric grid defined by all of these images. Each volume element of the grid, or voxel, is assigned a numerical value, for example representative of a quantity of absorbed X-ray radiation, obtained for example from the values of the pixels surrounding the voxel. Alternatively, the internal three-dimensional model may be determined by the X-ray analysis module 118. The method continues in step 128. Steps 124 and 126 may be performed in any order.

In step 128, the processing module 112 maps the external three-dimensional model provided in step 124 to the internal three-dimensional model provided in step 126. This can be done as follows. The processing module 112 determines a first three-dimensional mark sional, also called first system of three-dimensional coordinates associated with the external three-dimensional model, based on which are marked the elements of outer three-dimensional model and a second three-dimensional coordinate, also called second coordinate system tridimension ^¬ tional associated with the internal three-dimensional model, report that identifies the elements of the internal three-dimensional model. Each marker can be determined by a point of origin, also called reference point thereafter, and three vectors. By way of example, for the locating elements 1, 40, 50, 60, 70, 80 and 81, the first marker is determined from the analysis of the portion of the external three-dimensional model that corresponds to the element of 1, 40, 50, 60, 70, 80 or 81. More specifically, the processing module 112 determines the first marker from the recognition of the registration faces of the registration element that are present in the external three-dimensional model. . By way of example, for the locating elements 1, 40, 50, 60, 70, 80 and 81, the second marker is determined from the analysis of the portion of the internal three-dimensional model that corresponds to the element of 1, 40, 50, 60, 70, 80 or 81. The processing module 112 determines the second marker from the recognition of the insert or radiopaque inserts 30, 42, 44, 46, 52 or 54 present in the internal three-dimensional model. For the registration elements 1, 40, 50, 60, 70, 80, 81 or the marking device 91, the processing module 112 then determines the transformation of the passage between the first marker and the second mark, that is to say say the three-dimensional geometric transformation that connects the first and second landmarks. By way of example, for the registration elements 1, 40, 50, 60, 70, 80 and 81, the passage transformation is determined from the relative position between the registration faces and the radiopaque inserts which is known from the design of the marker element. By way of example, in the case of the registration element 1 represented in FIG. 1, the algorithm for determining the first marker associated with the external three-dimensional model may comprise the following steps:

determination of the planar registration faces 12, 14 and

16 by a surface recognition algorithm;

determining the edge 18 common to the faces 12 and 14, the edge 20 common to the faces 12 and 16 and the edge 22 common to the faces 14 and 16;

determining the origin point of the first marker corresponding to the point 0 common to the edges 18, 20 and 22; and

determining three non-coplanar vectors defining the first marker, two vectors being given by the edges 18 and 20 and the third vector being equal to the vector product of the two vectors defined previously.

Alternatively, in the détermi algorithm ^¬ nation's first reference associated with the external three-dimensional model described above, the face 4 can be used instead of the face 12. Further, the one identification element described above with a symmetrical structure, the registration faces 34, 36 and 38 can be used in place of the faces 12, 14 and 16.

The use of the registration element 1 shown in FIG. 1 may be advantageous insofar as the registration faces 12, 14 and 16 are inclined at 45 ° relative to one another. Indeed, this reduces the risk that one of the registration faces 12, 14, 16 is not visible on the images acquired by the optical camera 116 relative to registration faces which would be inclined relative to each other. an angle of 90 °. By way of example, in the case of the marker element 70 shown in FIGS. 6 and 7, the algorithm for determining the first marker associated with the external three-dimensional model may comprise the following steps:

determining the registration faces 12, 72 and 16 by a surface recognition algorithm; determining the edge 74, corresponding to an arc of a circle, common to the faces 12 and 72 and determining the center of this arc which corresponds to the point of origin of the first marker;

determining the edge 20, corresponding to a line segment, common to the faces 12 and 16, the center of the arc 74 being located on this segment 20; and

determination of three non-coplanar vectors def ^¬ nishing the first marker, the first vector corresponding to the edge 20, the second vector being perpendicular to the first vector, passing through the point of origin and being contained in the face 12, the third vector being equal to the vector product of the first and second vectors defined above.

By way of example, in the case of the marker element 80 shown in FIGS. 8 and 9, the algorithm for determining the first marker associated with the external three-dimensional model may comprise the following steps:

determining the registration faces 82, 84 and 16 by a surface recognition algorithm;

determination of the edge 86, corresponding to an arc of a circle, common to the faces 82 and 84, determination of the center of this arc of circle, which corresponds to the point of origin of the first marker, and determination of the plane containing this arc of circle ;

determining the intersection of the face 16 and the plane containing the arc 86 which gives a segment on which is located the center of the arc 86; and

determining three non-coplanar vectors defining the first marker, the first vector corresponding to the intersection segment of the face 16 and the plane containing the circular arc 86, the second vector being perpendicular to the first vector, passing through the point of origin and being contained in the plane containing the arc 86, the third vector being equal to the vector product of the first and second vectors defined above. In the case of the registration element 1 represented in FIG. 1 which comprises a radiopaque parallelepiped 30, the algorithm for determining the second marker associated with the internal three-dimensional model may comprise the following steps:

determination of all the voxels of the internal three-dimensional model belonging to the radiopaque insert 30;

determination of the center of gravity of the radiopaque insert 30;

determination of the inertia matrix of the radiopaque insert 30; and

determination of the eigenvectors of the inertia matrix.

The second mark is defined by the center of gravity of the radiopaque insert 30 and the three eigenvectors of the inertia matrix of the radiopaque insert 30.

In general, the shape of the radiopaque insert 30 may be different from that of a parallelepiped as long as it is adapted to allow the determination of distinct and unique eigenvectors of the inertia matrix of the insert.

For example, in the case of the marking element 40 shown in Figure 3, the algorithm détermi ^¬ nation of the second reference associated with the internal three-dimensional model may comprise the steps of:

determination of all the voxels of the template tridimen ^¬ internal dimensional belonging to the spheres 42, 44, 46;

determining the centers of the spheres 42, 44, 46;

determining a first vector corresponding to the vector connecting a first center (for example the sphere of larger diameter) and a second center (for example the sphere of intermediate diameter) and a second vector corresponding to the vector connecting the first center and the third center (for example the sphere of smaller diameter); determining a third vector from the vector product of the first and second vectors; and

determining the origin of the second marker corresponding to one of the centers.

For example, in the case of the marking element 50 shown in Figure 4, the algorithm détermi ^¬ nation of the second reference associated with the internal three-dimensional model may comprise the steps of:

determination of all the voxels of the internal three-dimensional model belonging to the radio-opaque inserts 52, 54;

determining the axes of the tubes 52, 54;

determining the minimum distance point between the two axes of the tubes 52, 54 which corresponds to the origin of the second marker;

determining a first vector corresponding to the director vector of the axis of the tube 52 and a second vector corresponding to the director vector of the axis of the tube 54; and

determining a third vector from the vector product of the first and second vectors.

For example, when the tracking device

91 is used, the determination of the first marker, the second marker and the passage transformation between the first marker and the second marker can be performed as follows.

The first mark may correspond to the own mark of the external three-dimensional model used by the optical and / or tactile analysis module 116 and / or the processing module 112 during the supply of the external three-dimensional model. The second mark may correspond to the internal mark of the internal three-dimensional model used by the X-ray analysis module 118 and / or the processing module 112 during the supply of the internal three-dimensional model.

By way of example, in the case where the tracking device 91 is used, the transformation of passage between the first landmark and the second landmark may include the following steps:

determining a first reference point for each unit locator element 81 in the outer three-dimensional model. The first reference point may correspond to the origin point of the first marker which is determined in the case where the marker element 81 is used alone and which can be determined according to the embodiments described above. The coordinates of each first point are expressed in the first marker;

determining a second reference point for each unit locator element 81 in the internal three-dimensional model. The second reference point may correspond to the origin point of the second marker which is determined in the case where the marker element 81 is used alone and which can be determined according to the embodiments described above. The coordinates of each second point are expressed in the second marker;

determining a third reference point for each unit locator element 81 in the second marker. For each registration element 81, the third reference point of the registration element corresponds to the first reference point whose coordinates are expressed in the second reference. This can be achieved by applying a translation to the second reference point, the applied translation vector being known from the design of the unitary registration element 81; and

determining from the first reference points and the third reference points of the passage transformation between the first marker and the second marker. This transformation can be determined according to the algorithm described in the publication entitled "Least-Squares Fitting of Two 3-D Points Sets" in the names of KS Arun, TS Huang and SD Blostein (IEEE Transactions On Pattern Analysis). And Machine Intelligence, Vol. PAMI-9, No. 5, pp 698-700, September 1987).

In general, for the implementation of this algorithm, N is considered to be an integer equal to or greater than 3, a first set of points Pj_ of coordinates (Xj_, Yj_, Z-j_) in the first frame where i is a an integer varying from 1 to N, and a second set of points P'i of coordinates (X'j_, Y'j_, in the second frame where i is an integer ranging from 1 to N. The points Pj_ may correspond to first reference points described above and the points P'i may correspond to the third reference points described above.

The transition transformation from the first marker to the second marker is given by the matrices R and T which satisfy the following relation (1):

P'i = R.Pi + T + ¾ ₍₁₎ where R is a rotation matrix, T a translation vector and N-j_ is a noise vector. The matrix R and the vector T are determined to minimize the criterion S defined according to the following relation (2):

We call P the center of gravity of the points Pj_, P 'the center of gravity of the points P'i, the points Qi of coordinates (¾χ' ¾y / ¾ _. Z) in the first reference given by Qi = Pi - P for i varying from 1 to N and the points Q'i of coordinates (q'i _x , q'iy, q'i _z ) in the second reference given by Q'i = P'i -P 'for i varying from 1 to N. The relation (2) then becomes the following relation (3):

The covariance matrix H is used according to the following relation (4)

Rix - Rix-iy Rix- R iz

H = Σi Riy R ix Riy Riyy Riy R iz (4;

Rice Rice Rice Rice Rice Rice. The matrix H is decomposed into singular values U and V according to the following relation (5):

H = UAV ^t (5)

The matrix R and the vector T are given by the following relations (6):

R = VU ^t (6)

T = P '- R.P

At a point B whose coordinates are expressed in the first mark corresponds to a point B 'whose coordinates are expressed in the second mark. The points B and B 'are connected by the following relations (7):

B'i = R.Bi + T ₍₇₎ Bi = R ^_1 .B'i - R ^_1 .T

An advantage of the method implementing the locating device 91 is that the passage transformation can be determined with a better accuracy than when using a single locating element 1, 30, 40, 50, 60, 70, 80 or 81.

The process continues in step 130.

In step 130, the practitioner determines the position of the implants. For this purpose, the practitioner uses both the internal three-dimensional model and the external three-dimensional model. For example, on the interface module of the display screen 114, the external three-dimensional model and sorting model ^¬ internal dimensional can be represented simultaneously on the same image, the external three-dimensional model being positioned correctly relative to internal three-dimensional model. For example, the external three-dimensional model is added in transparency to the internal three-dimensional model. The practitioner can see on the same image both the bone system of the patient's jaw on which the implants must be fixed and the outer surface of the soft tissues, including gums, covering the bone system. The practitioner can then add to the internal and external three-dimensional models, by via the interface 114, the three-dimensional model of the outer surface of virtual teeth. For each implant, the practitioner can then determine the ideal axis of drilling for the implantation of the implant from the external three-dimensional model supplemented by the virtual teeth. The axis can be transferred to the internal three-dimensional model using the transfer matrix. The practitioner can then adjust the position of the axis of the implant according to the bone structure of the patient's jaw.

In the case where a surgical guide is to be performed, the practitioner can, in addition, determine, from the internal three-dimensional model and with the position of the axes of the implants, a three-dimensional model of a gutter whose intrados corresponds to the three-dimensional model. external. In addition, the practitioner can add, on the three-dimensional model of the gutter, the openings necessary for the passage of the piercing tool from the position of the axes of the implants. The processing module 112 can then transmit the three-dimensional model of the gutter to the computer-assisted manufacturing tool 120 for the manufacture of the surgical guide. The surgical guide can be manufactured by three-dimensional machining processes or additive manufacturing processes, for example by selective laser melting, selective laser sintering, 3D printing or stereolithography.

In general, the embodiment of the dental implant preparation method according to the invention described above can be implemented with any registration element which can be located both in the external three-dimensional model. and the internal three-dimensional model.

FIG. 16 represents a block diagram illustrating a variant of the embodiment of the dental implant preparation method according to the invention described previously. in relation to FIG. 15 in which step 124 comprises the following sub-steps 150, 152 and 154:

In step 150, a first external three-dimensional model of the teeth and gums of the lower or upper part of the patient's mouth at which a prosthesis is to be placed is determined, while a first registration element 1 or a first locator 91 is attached to a tooth, multiple teeth, or gingiva of that portion of the mouth, as previously described. The process continues in step 152.

In step 152, a second additional external three-dimensional model of the teeth and gums of the other, lower or upper, part of the patient's mouth is determined, while a second registration element 1 or a second tracking device 91 is attached to a tooth, to several teeth, or to the gum of that other part of the mouth. The process continues at step 154.

At step 154, a third external three-dimensional model of the teeth and gums is determined while the two lower and upper portions of the patient's mouth are occluded, the first and second locating elements 1 or locating devices 91 being present at the same positions as when determining the first and second external three-dimensional models. The third external three-dimensional model is necessarily incomplete since the patient's mouth is in occlusion. However, the third external three-dimensional model makes it possible to know the relative position between the first and second registration elements 1 or marking devices 91 when the mouth of the patient is in occlusion. The processing module 112 is then adapted to place the first three-dimensional model relative to the second three-dimensional model when the mouth of the patient is in occlusion.

Therefore, at step 130, the practitioner can take into account by adding virtual teeth to the first three-dimensional external model of constraints determined from the study of the first and second three-dimensional external models in occlusion.

FIG. 17 represents a block diagram illustrating a variant of the embodiment of the dental implant preparation method according to the invention described above in connection with FIG. 15 adapted to the case where the patient no longer has teeth. at the maxillary level in which an implant must be placed and uses a denture. According to this variant, the step 124 described above comprises the following sub-steps 156 and 158:

In step 156, a first external three-dimensional model of the inside of the mouth is determined in the presence of the denture, while a first marker element 1 or a first marker device 91 is attached to this denture by gluing, for example . The first external three-dimensional model includes the outer surface of the false teeth of the denture. The process continues in step 158.

In step 158, a second three-dimensional model of the outer surface of the patient's denture is determined while the patient no longer has the denture in the mouth and the denture is outside the patient's mouth. The purpose of the acquisition of the second external three-dimensional model is to have the intra ^¬ back of the denture corresponding to the gingival surface of the patient. The first and second external three-dimensional models are matched by means of the registration element 1 or the marking device 91 which provides a three-dimensional coordinate system in relation to the intrados surface and a three-dimensional coordinate system in relation to the external surface of the surfaces. fake teeth .

In step 128, the processing module 112 maps the first external three-dimensional model provided at step 156, the second external three-dimensional model provided at step 158, and the internal three-dimensional model provided at step 126. In step 130 described above, the practitioner can use the first three-dimensional model of the outer surface of the patient's denture as a starting point for adapting the position of the axes of the implants from the internal three-dimensional model. In the case where a surgical guide is to be performed, the practitioner uses the second external three-dimensional model which corresponds to the surface (called the intrados) of the surgical guide intended to be in contact with the gums and possibly the patient's palate.

Advantageously, the part of the registration element 1, 40, 50, 60, 70, 80, 81 which allows the recognition of the registration element in the external three-dimensional model, that is to say the faces 12, 14, 16, 34, 36, 38, 72, 82, 84, 89, and the part of the registration element 1, 40, 50, 60, 70, 80, 81 which allows the recognition of the in the internal three-dimensional model, that is, the radiopaque inserts 30, 42, 44, 46, 52, 54, are different. Indeed, recognition of the marking member in the external three-dimensional model advantageously implements surface recognition algorithms while the recon ^¬ birth of the marking member in the tridimen ^¬ dimensional internal model advantageously implements volume recognition algorithms. This is advantageous insofar as the accuracy of the images obtainable by an X-ray scanner is generally poorer than the accuracy of the images that can be obtained by an optical camera or a probe. The implementation of volume recognition algorithms makes it possible to ensure the more robust determination of the marker associated with the internal three-dimensional model despite the inaccuracy of the images obtained by an X-ray scanner.

The shape of the part of the registration element 1, 40, 50, 60, 70, 80, 81 which allows recognition of the registration element in the external three-dimensional model can therefore be optimized for surface recognition algorithms and the shape of the part of the registration element 1, 40, 50, 60, 70, 80 which allows recognition of the registration element in the internal three-dimensional model can therefore be optimized for volume recognition algorithms.

However, if the accuracy of the images obtained by an X-ray scanner allows it, the determination of the reference associated with the external three-dimensional model can be achieved by surface recognition algorithms from characteristic faces of the insert.

In addition, it may be advantageous if the entire registration element is not made of radio-opaque material. Indeed, if the entire tracking element was made of radiopaque material, it may occur artifacts on the images acquired by the optical camera. In addition, if the entire locating element was made of radiopaque material, it would be difficult both to locate the radiopaque element under the line teeth / gums to avoid obtaining artifacts on the images acquired by the CT scanner and place at least some registration faces near the occlusion plane to facilitate the acquisition of images by the intraoral camera.

However, in particular cases of complete edentulousness, the entire locating element may be made of radio-opaque material, insofar as the risks of artefacts on the images acquired by the CT scanner are reduced.

According to the embodiment of the preparation method described above in connection with FIG. 15, it is not necessary to make a plaster copy of the patient's mouth to make the piercing guide. In addition, the steps of acquisition of the images by the camera 116 and image acquisition by the scanner 118 can be performed in a single session that may not last more than 20 minutes. The duration between the acquisition of the images and the manufacture of the surgical guide may, in addition, be reduced, for example less than half a day. Locating element 1, 40, 50, 60, 70, 80 or 81 may advantageously be attached directly to the side wall of a tooth or to the gingiva of the patient. It is therefore not necessary to provide a gutter which at least partially covers the teeth of the patient and which would be fixed 1 locating element.

Particular embodiments of the present invention have been described. Various variations and modifications will be apparent to those skilled in the art. In particular, even if the registration element shown in FIG. 4 has been described with radio-opaque inserts 52, 54 of tubular shape, it is clear that each tube 52, 54 can be replaced by a conical or frustoconical shaped element. , possibly hollow. Furthermore, even if embodiments have been described in which the registration element is temporarily bonded to a tooth or gingiva of a patient, it is clear that the registration element can be secured. by any means in the patient's oral cavity when acquiring images by X-ray scanner and images by the optical camera. For example, the registration element can be attached to the teeth by a mechanical holding system, for example a clamp. In addition, even if in the embodiments described above, the radiopaque inserts 30, 42, 44, 46, 52, 54 are completely embedded in the block, and in particular covered by the registration faces, it is clear that a portion of the radiopaque insert may protrude out of the block.

Various embodiments with various variants have been described above. It is noted that one skilled in the art can combine various elements of these various embodiments and variants without being creative. For example, radiopaque inserts, such as paralle ^¬ lépipède 30 shown in Figure 1, the tubes 52, 54 shown in Figures 4 and 7, the spheres 42, 44, 46 shown in Figures 3 and 9 , can be used with any of the registration elements 1, 60, 70, 80 or 81.

Claims

A method for preparing at least one dental implant, comprising the steps of:

attaching at least one registration element (1) to at least a portion of the oral cavity of a patient;

acquisition, by an optical sensor (116) or a probe, of data relating to said at least part of the oral cavity;

acquiring, by an X-ray scanner (118), data relating to at least a portion of the bone system of the patient's jaw;

computer recognition of faces (12, 14, 16, 42, 44, 46) of said at least one registration element in the first model;

computer recognition of at least a portion (30) of said at least one registration element in the second model;

computer determination of a second coordinate system associated with the second model;

computer determination of a passing relation between the first coordinate system and the second coordinate system from said faces and said portion; and determining the position of said implant from the first model and the second model and from the first three-dimensional coordinate system, the second coordinate system, and the transit relationship.

The method of claim 1, wherein the step of determining the position of said implant from the first model and the second model and from the first coordinate system and the second coordinate system comprises the steps of:

The method of claim 1 or 2, further comprising the steps of:

acquiring, by the optical sensor (116) or the probe, data relating to said other part of the oral cavity;

acquiring, by the optical sensor (116) or the probe, data relating to the registration element (1) and to the additional registration element when the mouth is in occlusion; and

providing a three-dimensional model of the outer surface of the registration element and the additional registration element when the mouth is occluded.

4. The method of claim 3, wherein the step of determining the position of said implant is performed from the first model and the three-dimensional model. the outer surface of said other portion of the oral cavity occluded.

The method of claim 1, wherein a denture is capable of being placed on said portion of the oral cavity, wherein the first model is determined in the absence of the denture, the method further comprising the steps of :

placing the denture on said part of the oral cavity;

acquisition, by the optical sensor (116) or the probe, of data relating to the denture; and

6. Method according to any one of claims 1 to 5, wherein the step of determining the second coordinate system comprises determining the inertia matrix of said portion (30).

7. Method according to any one of claims 1 to 6, further comprising determining the drilling axis of said implant, determining a three-dimensional model of a gutter comprising a cylindrical opening along the axis of drilling said implant and computer-aided manufacturing said gutter comprising said opening.

The method of any one of claims 1 to 7, further comprising the steps of:

computer recognition of faces (12, 14, 16) of each registration element in the first model;

computer recognition of at least one portion (30) of each registration element in the second model; computer determination, for each registration element, of a second reference point in the second model; and

computer determination of the passage relationship between the first coordinate system and the second coordinate system from the first three reference points and the three second reference points.

9. System (110) for preparing for the placement of dental implants, the system comprising:

at least one registration element (1; 40; 50) comprising at least three non-parallel faces (12, 14, 16) visible by an optical camera (116) and / or a probe and at least one portion (30) locatable to X-ray, said registration element being adapted to be attached to at least a portion of the oral cavity of a patient;

an optical image sensor (116) or probe adapted to acquire data relating to said at least a portion of the oral cavity;

an X-ray scanner (118) adapted to acquire data relating to at least a portion of the bone system of the patient's jaw; and

a processing module (112, 116, 118) connected to the X-ray scanner and the optical image sensor and / or the probe, the processing module, the optical image sensor and / or the X-ray scanner being adapted to provide a first three-dimensional model of the outer surface of said at least a portion of the oral cavity from data relating to said at least a portion of the oral cavity, providing a second three-dimensional model of said at least a portion of the bone system of the jaw of the patient from data relating to said at least part of the bone system of the jaw, recognizing the faces in the first model, determining a first three-dimensional coordinate system associated with the first model, recognizing said at least a portion in the the second model, determine a second system of coordinates associated with the second model, determining a transition relationship between the first coordinate system and the second coordinate system from said faces and said portion, and determining the position of said implant from the first model and the second model and to from the first three-dimensional coordinate system and the second coordinate system.

The system of claim 9, wherein said faces are of an X-ray transparent material.

The system of claim 10, wherein the X-ray transparent material is further opaque to visible light.

The system of claim 10 or 11, wherein at least two faces (12, 14) of said three faces are flat and inclined relative to each other by an angle of between 5 ° and 85 ° or between 95 ° and 270 °.

13. System according to any one of claims 9 to 12, wherein at least one of the faces (72; 82) corresponds to a sphere portion or to a cylinder portion.

14. System according to any one of claims 9 to 13, wherein said portion (30) is covered by said faces (12, 14, 16).

15. System according to any one of claims 9 to 14, wherein said portion comprises at least two tubes

(52, 54) rectilinear and non-concurrent.

The system of any one of claims 9 to 15, wherein said portion comprises at least three spheres (42, 44, 46) whose centers are not aligned.

The system of claim 16, wherein the spheres (42, 44, 46) have different diameters.

18. System according to any one of claims 9 to 17, wherein said portion comprises at least one parallelepiped (30).

19. System according to any one of claims 9 to 18, wherein said at least one marker element comprises at least first, second and third non-parallel planar faces (12, 14, 16), at least the first face ( 12) being inclined with respect to the second face (14) by an angle of between 5 ° and 85 ° or between 95 ° and 270 ° and the first face (12) being inclined with respect to the third face (16) of an angle of between 5 ° and 85 ° or between 95 ° and 270 °.

20. System according to any one of claims 9 to 19, comprising at least three separate marker elements (81) each comprising at least three non-parallel faces (12, 14, 16) visible to the optical camera (116) and / or the probe and at least one portion (30) X-ray locatable, each marker element being adapted to be attached to at least a portion of the oral cavity of a patient.