FR2804859A1 - Method for guiding the movement of a tooth insertion tool towards a point over a tooth cavity, used for inserting new teeth into a jaw tooth cavity aided by three dimensional imagery - Google Patents

Abstract

Method for guiding a point reference point (Pr) with respect to a body (K): (a) produce a first 3D of the body using a first light beam; form a second 3D image, defined by a number of end image points corresponding to points sampled from the bodies surface; index the first image with respect to the second and a set reference to produce a reference image; form an image of the point (Pr) in the set reference; guide the point using the third image to the body : One of the beams mat be at least one of the following: X ray; light; ultrasound. The second image is produced using a robotic arm. The first, second and third images are in the form of videos which can be displayed on a video screen. A fourth 3D image can be produced using the second beam partially reflecting from the body surface and to process the first image using the fourth to produce a corrected image of the first. An Independent Claim is included for a referencing and image producing system which includes: X ray source (5); scintillator (6); converter (7); processor (8); video display (10); laser generator (11); robotic arms(12,13); tooth insertion tool (16); ultrasound source (18);light ray sensor (19); ultrasound reflection sensor (20); computer control program (28).

Description

The present invention relates to methods for guiding the displacement of at least one reference point with respect to a body, which find an advantageous application in the medical field and more particularly in the dental field for, for example, to help dentists to achieve dental implants.

The present invention also relates to devices for carrying out these methods, for guiding the displacement of at least one reference point relative to a body.

Modern dental techniques can replace damaged teeth with artificial teeth that are implanted, for example by means of pivots. To be able to implant these teeth it is necessary to realize, in the bone part of the maxillary a pilot hole in which is disposed the pivot of the replacement tooth.

It is obvious that, for the replacement tooth to be perfectly positioned, particularly with respect to the surrounding teeth remaining and relative to the maxillary, it is necessary that the axis of the pilot hole is perfectly defined. However, the location where the pilot hole must be made is often difficult to access and generally does not have excellent visibility, which does not allow the practitioner to realize for sure precisely a pilot hole ideally located.

Thus, the purpose of the present invention is to implement a method guiding the displacement of at least one reference point with respect to a body, which makes it possible, particularly in the dental field but not exclusively, to perform more easily work of very good quality, while reducing the time of intervention on patients.

More specifically, the subject of the present invention is a method for guiding the displacement of at least one reference point relative to a body, characterized in that it consists in producing the first 3D image of the body by means of a first radiation beam, to produce a second 3D image of said body, this second 3D image being defined by a plurality of finite number image points corresponding to sample points of the surface of said body, said sample points being defined with respect to a given reference frame indexing the first 3D image with respect to the second 3D image to obtain a third 3D image referenced in said repository, making an image of said point in said repository, and guiding said point with respect to said body in said repository by means of said third 3D image and the image of said point.

The present invention also relates to a device for covering the method defined above for guiding the displacement of at least one reference point relative to a body, characterized in that it comprises: means for carrying out a first 3D image of the body by means of the first radiation beam, means for producing a second 3D image of said body, this second 3D image being defined by a plurality of image points in finite number corresponding to sample points on the surface of said body, these sample points being defined with respect to a given repository, means for indexing the first 3D image with respect to the second 3D image to obtain the third 3D image referenced in said repository, means for producing an image of said point in said repository, and means for guiding said point relative to said body in said reference frame by means of said third me 3D image and image of that point.

Other features and advantages of the invention will become apparent from the following description given with reference to the accompanying drawings for illustrative but not limiting purposes, which FIG. 1 is the block diagram for implementing the method according to the invention for guiding displacement of at least one reference point relative to a body, and Figure 2 shows the block diagram of a device for implementing the method according to the invention, in an application in the dental field.

The present invention relates to a method for guiding the displacement of at least one reference point Pr relative to a body K which finds advantageous applications in the medical field, and more particularly dental.

An example of implementation of the method is described below in a dental application for very accurately implanting artificial teeth by means of pivots or the like, it being understood that this method can also be applied without any difficulty in other fields of application and whatever the nature of the body K.

The block diagram of the method according to the invention is shown in FIG. 1. With reference to this diagram, the method consists in firstly producing a first 3D image of the body K, a three-dimensional image (FIG. 1, FIG. 1). , means of a first radiation beam.

In the case of the application of the method to the dental field, first image 3D is that of the part of the jaw 1 comprising the location 2 the tooth to be replaced and the set of teeth 3 which are in the vicinity of this location 2, as well as that of the portion of the maxillary bone 4 which bears these teeth 3 and this first 3D image is obtained by means of at least one of the following radiation beams <B>: </ B> beam of radiation X, beam of light radiation, ultrasound beam or the like. In the embodiment illustrated in FIG. 1, the first radiation beam used is an X-ray beam (RAY.X) which advantageously allows penetration into the tooth enamel and dentine, as well as into the bone in which the teeth are implanted.

Such a 3D image is obtained in a manner well known in itself. It can be obtained by means of, for example, an X-ray source, FIG. 2, a scintillator 6 which receives the X-rays which have passed through the body and which transforms them into light signals, and a converter 7, as a CCD sensor or the like, which converts these light signals into analog or digital electrical signals. These electrical signals are then processed by means of a processing unit 8 controlled by a programmer 28 of the computer type or the like, known per se, to form a video image 9 displayed on a video screen 10 or the like.

The method then consists in producing (ARM AR, FIG. 1) the second 3D body image (image II, FIG. 1), this second 3D image being defined by a plurality of image points in finite number corresponding to sample points the surface of the body these sample points being defined with respect to a given reference frame.

This second 3D image can be obtained in a manner known per se, for example by means of a poly-articulated robot measuring arm, schematically illustrated at 12 in FIG. 2. The signals delivered by the poly-articulated arm each when it is pointed at a sample point of the surface of the body K are applied to the input of the processing member 8 which transforms them into signals which are processed to give image points, for example video, which, because of of the structure of the robot arm 12, are perfectly determined and referenced by an address in a repository R (for example X, Y and Z), Figure 2, for example linked to the robot itself.

When this second 3D image has been obtained, the method consists of indexing the first 3D image with respect to the second 3D image, for example in the processing element 8, FIG. the same means for example of commercially available image displacement control software which makes it possible to move a video image on a video screen, in this case the first 3D image, to superimpose it on another video image , in this case the second 3D image, so that the maximum number of image point sample points merge with the corresponding image points of the first 3D image. In theory, three sample points are sufficient to obtain this superposition, but it is obvious that the result will be easier to obtain and more reliable if the number of sample points is larger.

When these two first and second 3D images are superimposed, we obtain a t <B> 1 </ B> th image <B> D </ B> (image <B> 111, </ B> figure <B> 1) </ B> same <B> to </ B> the first but referenced in the ro if <B> -1 1 </ B> repository defined above, each of its points being defined its address in this repository.

The method then consists in producing an image of the point Pr in the same reference frame R (MAN ARM, FIG. 1), for example with an articulated robot arm 13 of the same type as that described above, which is displayed in FIG. picture 9 on the video screen <B> 10, </ B> figure 2.

At the stage of the process, it is easy to guide the point P with respect to the body K in the same frame of reference R by means of the third 3D image and the image of the point Pr which are combined in the same image 9 on the screen. video screen 10, as shown in FIG.

 this representation, the body K is the jaw 1 of a patient and the point Pr is for example a point related to the drill bit 16 for drilling the maxillary bone 4 to prepare the implantation of a replacement tooth to the 2. The wick 16 being connected to the treatment member 8 by the articulated arm 13, it is easy for the practitioner to position it exactly at the desired location 2 of the body K, by a simple observation of the image 9 on the video screen without having to observe in situ the movement of this wick itself.

The method described above can be implemented, with the proviso that the body K is immobile with respect to the reference frame R.

It is quite obvious, however, that in the case of a body K such as the dentition of a patient, the last can never be strictly immobile. Consequently, to compensate for displacements due to patient movements and to constantly know the body position K with respect to the reference frame R, it is very advantageous for the method according to the invention to furthermore index the body K with respect to the reference frame R. Also, the device for implementing the method according to the invention may further comprise means for indexing the body K with respect to the reference frame R. These means may be of any type, for example an arm 22 of the same type as which are referenced 12 or 13. This indexing makes it possible to position the third 3D image as a function of the movements of the body K and to obtain at all times, on the screen, a perfect correlation between this third 3D image and the real position of the patient.

The process described above gives good results in itself. However, in the case where the first radiation beam is an X-ray beam, the image obtained may have dark parts or parasitic images due in particular to the diffusion of X-rays which limit its quality. This is the case of the first 3D image.

Indeed, it is not unusual for the X-rays used for producing the first 3D image to encounter, for example in a dentition or the like, opaque materials with X-rays, for example amalgams, ceramics or the like, which oppose to their penetration and reflect and diffuse them into the surrounding space. The first 3D image obtained therefore often includes parasitic images known to technicians as artifacts.

Also advantageously, the method consists, in addition to the phases described above, to produce a fourth 3D image of the body K by means of a second beam of radiation at least partially reflecting on the surface of the body.

However, especially when the part of the body K, for example a part 3, 21, 4 of the dentition of a patient, which must be treated is difficult to access, the fourth 3D image (image IV, FIG. 1) can be carried out indirectly. on a recessed impression (negative technique) of this part of teething, performed previously (empty CAM, Figure 1). It is also possible to make the fourth 3D image on a full cast (positive technique) obtained from the indentation.

Advantageously, this fourth 3D image is obtained by scanning the part of the dentition to be treated by means of a beam of light radiation, for example that which is delivered by a laser generator 11 or the like. This technique called by image technicians obtained by scanner is well known in itself and will not be more fully described here.

The method then consists in processing the first 3D image by the fourth 3D image to obtain first corrected 3D image of its artifacts (COR, FIG. 1). In this way, the first corrected 3D image of its artifacts displayed on the video screen 10 represents perfectly in volume, the body K which must be analyzed, that is to say in the case of the application cited as for example, all the part of the dentition concerned for implantation of a replacement tooth, this representation of the body K comprising a minimum number of defects that could disturb the practitioner's observation.

It is however specified that, to obtain the fourth 3D image of a body which is for example covered with a surface layer of a material such as the flesh 21 of the gum, it is advantageous to use a radiation that passes through this material. but which is reflected by the main constituent material of the body, for example the maxillary bone. In the field of application cited above by way of example, such radiation is for example that given by an ultrasound source 18.

Thus, in the advantageous application example described above, the fourth 3D image can be obtained in situ, by means of two beams, a beam of light radiation for the crown of the teeth and an ultrasound beam for the neck of the teeth. and the maxillary bone. Those skilled in the art know the types of sensors necessary to receive the reflected light rays (sensor 19) or the reflected ultrasound (sensor 20) and to deliver signals that will be transmitted to the processing unit 8 controlled by the programmer 28.

When this fourth 3D image is obtained from a fingerprint or the like, it too, have defects. Therefore, advantageously, it is possible to check this fourth 3D image by means of the second, possibly to make corrections to it depending on the definition of this second image which, it is certain, since obtained directly from of the body itself.

The practitioner who wants to implant a tooth can visualize, on the third 3D image, the axis 15 according to which the replacement tooth will have to be implanted, which it has defined in a perfect manner with respect to the other teeth 3 and the bone of the tooth. maxillary 4. It can then position the wick 16 of the drill 14 and control its movement so that the axis of the wick is perfectly coincident with the axis of implantation 15 and remains constantly as and when it This operation is still possible, even if the patient moves because, by indexing in the same reference frame R via means 22, the third image moves in correlation with the movements. of the patient, which allows the practitioner to be able to constantly position the wick 16 in a correct manner relative to the patient.

The example given above is an application to the dental field, but it is understood that such a method finds equally advantageous applications, for example, in the field of surgery or microsurgery including endoscopy.

Claims (11)

1. A method for guiding the displacement of at least one reference point (Pr) with respect to a body characterized in that it consists in producing first 3D image of the body by means of a first radiation beam, to be produced a second 3D image of said body, said second 3D image being defined by a plurality of finite number image points corresponding to sample points of the surface of said body, said sample points being defined with respect to a given frame of reference, to index the first image 3D with respect to the second 3D image to obtain third image referenced in said repository, to realize image of said point (Pr) in said repository, and to guide said point (Pr) relative to said body in said repository by means of said third 3D image and the image of said point (Pr). 2. Method according to claim 1, characterized in that said first beam of radiation at least one of the following radiation beams: X-ray beam, beam of light radiation, ultrasonic beam. 3. Method according to one of claims 1 and 2, characterized in that said second 3D image obtained by means of a poly-articulated robotic measuring arm. 4. Method according to one of claims 1 to 3, characterized in that it consists in producing said first, second and third 3D images in videographic form so that they are able to be viewed on a video screen. 5. Method according to one of claims 1 to 4, characterized in that it consists in producing a fourth 3D image of said body by means of a second radiation beam at least partially reflecting on the surface of said body, and process the first 3D image by the fourth 3D image to obtain a first corrected 3D image of its artifacts. 6. Method according to claim 5, characterized in that it consists in realizing the fourth 3D image 'from a footprint of said body, said fingerprint being produced according to one of the following techniques: </ B> "negative technique" and "positive technique". </ B> 7. Method according to one of claims 5 and 6, characterized in that it consists in checking the fourth 3D image from the second 3D image. 8. Method according to one of claims 5 to 7, characterized in that the second radiation beam at least partially reflecting on the surface of said body is at least one of the following beams: beam of light radiation, ultrasonic beam . 9. Method according to one of claims 1 to 8, characterized in that it consists in indexing said body relative to said reference (R). 10. Device for implementing the method according to one of the preceding claims, characterized in that it comprises: means (5, 6, 7, 8, 9, 10) for producing a first 3D image of the body (K) by means of a first radiation beam, means (8, 12, 10) for producing a second 3D image of said body (K), this second 3D image being defined by a plurality of image points in number finite corresponding to sample points of the surface of said body (K), said sample points being defined with respect to a given reference frame (R), means (8) for indexing the first 3D image with respect to the second 3D image to obtain a third 3D image referenced in said reference frame (R), means (8, 13, 10) for producing an image of said point (Pr) in said reference frame (R), and means (13, 14, 15) for guiding said point (Pr) with respect to said body (K) in said frame (R ) by means of said third 3D image and the image of said point (Pr). 11. Device according to claim 8, characterized in that it further comprises means (8, 10, 11, 19, 18, 20) for producing a fourth 3D image of said body (K) by means of a second radiation beam at least partially reflecting on the surface of said body, and means (8) for processing the first 3D image by the fourth 3D image to obtain a first corrected 3D image of its artifacts.