Design method of a prosthetic element

Technical area

The invention relates to a method of designing a prosthetic element.

Prior art

Nowadays, when a dental restoration is to be carried out on a tooth of a patient via the placement of a prosthetic element, it is usual for a dentist to proceed with a preparation of the tooth comprising, for example, the following steps: size tooth, followed by an impression of the cut tooth. This impression is sent to a laboratory for the design of the prosthetic element, the latter then being tested, possibly adapted, and finally placed on the patient's cut tooth.

Despite the advent of computer methods allowing this impression to be taken digitally, this entire dental restoration process is long and requires a certain number of appointments for the patient to see his dentist.

In addition, the size of the tooth by the dentist, the impression materials and the production flow in the laboratory are regular sources of technical errors jeopardizing the therapeutic effect expected by a dental restoration. In particular, it is complex for the dentist to take into account the overall structure of the hard and soft tissues associated with the patient's dentition, so that the size is only rarely perfectly adapted both to the patient and to the technical constraints of the patient. prosthetist producing the prosthetic element.

Summary of the invention

An object of the invention is to provide a method of designing a prosthetic element more suited to the needs of a patient,

enabling faster, cheaper and more reliable manufacture of said prosthetic element and treatment of the patient.

To this end, the present invention provides a method of designing a prosthetic element comprising the following steps, executed in this order:

(i) · provide a first computer file comprising:

an intraoral three-dimensional representation of a dentition comprising at least one tooth to be restored by means of the prosthetic element;

- an x-ray image of the dentition;

• identify common reference axes on the intra-oral three-dimensional representation and on the radiographic image;

• compare the intraoral three-dimensional representation with the radiographic image, this comparison sub-step comprising a superposition of the common reference axes;

(ii) determining a three-dimensional representation of an extrados of the prosthetic element on the basis of the first computer file;

(iii) determine technical parameters including:

a dental protocol, and / or

a type of dental preparation, and / or

technical constraints,

on the basis of the first computer file, at least one of the technical parameters being determined on the basis of the comparison sub-step of step (i);

(iv) generating a second computer file comprising a three-dimensional representation of a volumetric reduction of the at least one tooth based on the technical parameters; (v) validate and / or modify the second computer file;

(vi) obtain a three-dimensional representation of an intrados of the prosthetic element on the basis of the second validated and / or modified computer file;

(vii) generate a third computer file comprising information relating to the three-dimensional representations of the upper and lower surfaces of the prosthetic element;

(viii) produce the prosthetic element on the basis of the third computer file.

The method of designing a prosthetic element according to the invention makes it possible to implement a particularly efficient, inexpensive, and rapid dental restoration process, by providing a prosthetic element perfectly suited to the needs of a patient.

Indeed, this method mainly concerns digital steps performed prior to dental restoration. In particular, steps (ii) to (vii) are at the heart of the present invention, and are carried out by means of computer tools, in the background of the dental restoration. They make it possible to obtain a digital model of a prosthetic element capable of being perfectly adapted to the needs of a patient without any size of the at least one tooth being necessary beforehand. Step (ii) essentially concerns the external aesthetics of the prosthetic element, an extrados of which is determined in correspondence with the first computer file, and therefore globally, with the dentition of the patient and the overall structure of the soft and hard tissues. associated with this dentition. Steps (iii) to (vii) allow, among other things, to determine an intrados of the prosthetic element. This intrados must adapt perfectly to a size of the at least one tooth. However, in the case of the present invention, this pruning has preferably not been carried out in a concrete and real way beforehand, but rather virtually, in steps (iv) and (v), defined in the form of a volumetric reduction of the at least one tooth based on the information from the first computer file provided in step (i) and on the parameters deduced from this information in step (iii), preferably by a specialized computer scientist and / or a prosthetist experimented. Thus, the intrados is determined a posteriori essentially on the basis of this volumetric reduction. The second modified and / or validated computer file comprising the three-dimensional representation of the volumetric reduction therefore contains all the information necessary for carrying out this volumetric reduction, the latter making it possible to subsequently cut the at least one tooth so that its external surface cut exactly matches the intrados of the prosthetic element. Thus, and very advantageously, it is possible to digitally define and produce the prosthetic element thanks to the design method according to the present invention, and, only afterwards, to cut the at least one tooth on the basis of the definition of the reduction. volumetric of the at least one tooth contained in the second computer file after validation and / or modification.

In this context, the volumetric reduction (preferably defining a size) of the at least one tooth is therefore calculated before the lower surface of the prosthetic element, although subsequently, in practice, it is the prosthetic element which is produced before (or at the same time) as the volumetric reduction.

In the following close to the summary, detailed comments are made on the stages of the design method according to the invention. It is then presented various advantages of this method, in particular in the implementation of a dental restoration.

Step (i) advantageously makes it possible to provide a large amount of information on the dentition and the soft and hard tissues associated with this dentition to a dental prosthetist and / or a CAD designer in order to define more precisely the patient's needs, and therefore a prosthetic element more suitable by steps (ii) to (vii). It is proposed to provide one (or more) three-dimensional intraoral representation of the dentition, preferably uncut. This sub-step can be performed in less than thirty seconds by means of an intra-oral scanner known to a person skilled in the art. The x-ray image can be provided by any x-ray machine known to a person skilled in the art. It is preferably a two-dimensional image. Such an image is easier and less expensive to produce while giving enough relevant information for the comparison sub-step. A three-dimensional radiographic image (eg, produced by a conical beam volumetric imaging technique, or CBCT) is, however, not excluded from the scope of the invention. The images provided by this step (i) preferably make it possible to define very precisely a type of preparation and / or the technical constraints in step (iii), in particular by virtue of the comparison sub-step. Indeed, if it is counterintuitive to superimpose three-dimensional and two-dimensional data (for a two-dimensional radiographic image) this superposition is sufficient to identify, for example, the pulp chamber and the nervous system associated with the at least one tooth in order to take them fully into account in determining the technical parameters in step (iii). In particular, such an X-ray image is useful in the case of a dental restoration requiring re-cutting of a certain tooth, for example, in the case of removal of an old prosthetic element. Thus, it is easier to identify the certain tooth, as well as the soft and hard bodies associated with it.

Step (i) also comprises, an identification of the common reference axes on the intraoral three-dimensional representation and on the radiographic image, and a superposition of the common reference axes during the comparison sub-step. These axes play a primordial role in the work of the dental technician and / or the dentist because they make it possible to define an adequate digital work mark on the at least one tooth. In particular, they preferably comprise an axis of insertion of the at least one tooth. It is therefore crucial that these axes be determined very precisely. Said intra-oral three-dimensional representation is sufficient to determine such axes, but said radiographic image allows slight adaptation of these axes so as to take account of elements not visible on the radiographic image such as the pulp chamber and / or the nervous system associated with the at least one tooth. Thus the comparison of the images by superposition of the axes provides an excellent basis for the definition of an ideal digital working benchmark for the subsequent steps of the method, while making it possible to detect technical constraints which would not be directly apparent on a single representation. three-dimensional intraoral. In general, step (i) is very advantageous for planning both intelligently and precisely a volumetric reduction (and therefore a size) of the at least one tooth. Thus the comparison of the images by superposition of the axes provides an excellent basis for the definition of an ideal digital working benchmark for the subsequent steps of the method, while making it possible to detect technical constraints which would not be directly apparent on a single representation. three-dimensional intraoral. In general, step (i) is very advantageous for planning both intelligently and precisely a volumetric reduction (and therefore a size) of the at least one tooth. Thus the comparison of the images by superposition of the axes provides an excellent basis for the definition of an ideal digital working benchmark for the subsequent steps of the method, while making it possible to detect technical constraints which would not be directly apparent on a single representation. three-dimensional intraoral. In general, step (i) is very advantageous for planning both intelligently and precisely a volumetric reduction (and therefore a size) of the at least one tooth.

Optionally, step (i) also comprises a step of providing an image captured by UV and its superposition and / or comparison with the other data of the first computer file to detect the presence of caries, caries cavities and / or amalgam.

Steps (ii) to (vii) of the design method according to the present invention constitute intelligent planning and preparation steps prior to the good progress of a dental restoration. Various software known to a person skilled in the art make it possible to simulate and / or manipulate a three-dimensional image of a restored dentition.

It is possible to obtain a design of a probable extrados of a prosthetic element to restore the at least one tooth from such a simulation. This design achievement is nevertheless superficial because it does not indicate how to proceed with a dental restoration, nor how to produce a prosthetic element. In addition, by its very purpose, this design does not take into account many protocols and tolerances for manufacturing a prosthetic element adapted to the needs of a patient. This is why the design method according to the invention proposes to study the first computer file in step (i), so as to deduce therefrom the technical parameters of step (iii). These technical parameters preferably include at least one of: information on dentition, dental roots, gums, periodontal tissue, a gingival index, teeth which are adjacent to and / or antagonistic to the at least one tooth, information on the alignment and crowding of the teeth, the buccal areas of access, the nature of a material of design of the prosthetic element as well as the tolerances associated with this material, and in particular, the minimum thickness that the walls of the prosthetic element must have, and / or parameters specific to a production center of the prosthetic element. These elements preferably form an integral part of a dental protocol determined directly and algorithmically from step (i), and in particular therefore on the basis of the first computer file. Preferably, step (i) makes it possible to determine a type of dental preparation (comprising, for example, the type of dental preparation to be carried out, the at least one tooth to be restored, the type of prosthetic element and the minimum thickness that it must have, etc.) and preferably also an axis of insertion of the at least one tooth among the reference axes and / or axes of numerical size among these reference axes, these data being supplied as inputs to an algorithm advantageously making it possible to algorithmically generate a dental protocol on this basis. This is advantageously discussed later in this summary. these data being supplied as inputs to an algorithm advantageously making it possible to algorithmically generate a dental protocol on this basis. This is advantageously discussed later in this summary. these data being supplied as inputs to an algorithm advantageously making it possible to algorithmically generate a dental protocol on this basis. This is advantageously discussed later in this summary.

In this way, all the experience of a prosthetist is put at the service of a design of a prosthetic element, by the automatic establishment in step (iv) of a volumetric reduction plan of the at least one tooth taking into account all of these parameters. This automatic establishment is preferably carried out on the basis of a computer program specially designed advantageously within the framework of the present invention, preferably taking as input a dental protocol. This step (iv) gives rise to the generation of the second computer file. Step (v) of validating and / or modifying its content, and more specifically the three-dimensional representation of the volumetric reduction of the at least one tooth. Various parameters are thus preferably controlled by an authorized person, for example,

These steps (iv) and (v) are very advantageous because they make it possible to benefit from a help to determine the parameters to be taken into account to virtually define a prosthetic element while allowing freedom of validation and / or modification of this second. computer file obtained. In particular, the second computer file can be modified and is not the result of closed software providing an automatic design of a non-usable prosthetic element.

Preferably, the second computer file is an editable CAD file, preferably in STL format, defining a virtual size of the at least one tooth on the basis of steps (i) to (iii), so that it constitutes a file which can be delivered from step (iv), but also used and modified in step (v) and in subsequent steps. Step (v) preferably comprises a validation and / or a modification of each of the geometric parameters relating to the three-dimensional representation of the volumetric reduction of the at least one tooth. Preferably, these geometric parameters are among:

• peripheral margin lines,

• parallel planes bordering the lateral sides of the at least one tooth,

a gingival contour of at least one tooth,

size axes of the at least one tooth,

volumetric reduction zones of the at least one tooth, volumetric reduction faces of the at least one tooth, volumetric reduction quantities for each of the volumetric reduction zones of the at least one tooth.

All these parameters must be taken into account in establishing a prosthetic element. More preferably, each of the geometric parameters can be modified within a set of admissible values ​​defined beforehand by at least one of the technical parameters determined in step (iii), preferably by the dental protocol. This way, an inexperienced or distracted technician would not make mistakes in the design of the prosthetic component.

The second computer file thus validated and / or modified consequently comprises a three-dimensional representation of the volumetric reduction of the at least one tooth, and therefore can serve as a basis for obtaining in step (vi) a three-dimensional representation of the intrados of the prosthetic element, the latter being complementary to an external surface of the at least one volumetrically reduced tooth. The second computer file and the set of representations thus defined of the lower surface and the upper surface of the prosthetic element preferably constitute computer CAD files known to a person skilled in the art but advantageously usable according to the invention. The design of the prosthetic element being defined, a third computer file is then generated, preferably of the CAM type, comprising information relating to these three-dimensional representations of the intrados and extrados defining the design of the prosthetic element. This information serves as the basis for the production of the prosthetic element in step (viii) without losing the possibility of exploiting the information from the second computer file to guide a practitioner in the size of the at least one tooth in order to match. the volumetric reduction previously defined.

This third computer file differs from the second computer file in that it comprises technical information preferably directly exploitable during production of the prosthetic element, in particular by a production machine, whereas the second computer file preferably comprises data. three-dimensional representation. Obtaining the third computer file from the second is not done by existing software but from a computer program according to the invention to again take into account the technical parameters, and preferably very specifically to take account of prosthetic component design protocols and dental machining protocols. Preferably, the third computer file is also a CAM file,

Very preferably, the information of the third computer file comprises instructions for machining a material, and step (viii) comprises a sub-step for machining the material on the basis of the machining instructions. In this way, a machining machine capable of reading the instructions can machine a material to give it a hollow shape comprising an internal face similar to the representation of the lower surface and an external form similar to the representation of the upper surface. The material preferably comprises at least one of ceramic, zirconia, hybrid ceramic, composite, resin, so as to design a solid and biocompatible prosthetic element, allowing the patient to benefit from a dental restoration. healthy, durable and stable. Preferably,

Preferably, step (ii) of the method comprises the following sub-steps:

(11.1) choosing a model three-dimensional representation of a model dentition from a database on the basis of the first computer file;

(11.2) choosing an area of ​​the model three-dimensional representation corresponding to an area of ​​the intraoral three-dimensional representation corresponding to the at least one tooth;

(11.3) validate and / or modify the zone of the model three-dimensional representation on the basis of the first computer file;

(11.4) define the three-dimensional representation of the upper surface of the prosthetic element from the validated and / or modified zone of the model three-dimensional representation.

This preferred embodiment of the method essentially comprises a choice of three-dimensional representation of a flawless dentition simulating the three-dimensional representation of the dentition comprising the at least one tooth from a database (or library) of such representations. Thus, it is possible to determine a final shape of the restored dentition adapted to the needs of a patient, and to derive therefrom the shape of an external envelope to be given to the prosthetic element in order to optimize the aesthetics of this new final shape. teething. This outer shell basically consists of the upper surface of the prosthetic element. Since no model three-dimensional representation may correspond exactly to the desired upper surface, a validation and / or modification step similar to that of step (v) detailed above is provided for to allow a dental prosthetist and / or a CAD designer to perform alterations on this area. These can for example relate to an insertion axis, an axis and / or a

contact height of the at least one tooth with antagonistic and / or adjacent teeth, or else a dental alignment. A gingival index is preferably taken into account to define the three-dimensional representation of the upper surface.

In general, the design method according to the invention allows a reversal of an overall stage of preparation of the at least one tooth with a design of the prosthetic element, and this in an overall process of dental restoration which then stands out. very advantageously of the prior art, in that it is considerably more efficient and rapid. In particular, this dental restoration process proposes a preparation of the at least one tooth comprising a size of the at least one tooth adapted to the prosthetic element and not the other way around! An example of a very preferred embodiment of such a dental restoration process from the design method according to the invention is described in the detailed description below. More specificly, the long sequence of appointments between the patient and the dentist can advantageously be replaced by a single appointment during which, on the one hand, the at least one tooth is cut by a dentist according to information from the dentist. second computer file, and, on the other hand, the prosthetic element produced is placed on the at least one cut tooth. For example, in the case where the prosthetic element is a crown of a tooth, this dental restoration can be carried out during a single appointment lasting less than thirty minutes. The size of the at least one tooth on the basis of information from the second computer file is more exact and precise, because it is based on rigorous information, studied and analyzed by one or more specialists, and this on the basis of reliable numerical methods, away from the stressful working conditions of the dentist during dental surgery. The compatibility between the size of the at least one tooth, and the prosthetic element, on the one hand, and the overall structure of the tissues and of the dentition, on the other hand, is thus ensured and perfectly predictable. No impression should be taken after the size of at least one tooth because it is assumed that the prosthetic element will be adapted to this size with great precision, on the condition that this preparation is carried out on the basis of information. of the second computer file. is thus assured and perfectly predictable. No impression should be taken after the size of at least one tooth because it is assumed that the prosthetic element will be adapted to this size with great precision, on the condition that this preparation is carried out on the basis of information. of the second computer file. is thus assured and perfectly predictable. No impression should be taken after the size of at least one tooth because it is assumed that the prosthetic element will be adapted to this size with great precision, on the condition that this preparation is carried out on the basis of information. of the second computer file.

Advantageously, the design method according to the invention therefore makes it possible to avoid numerous round trips of the prosthetic element between a dental office and a laboratory where it is designed, such round trips being sometimes necessary depending on the condition of the prosthesis. the technique for adaptations of the prosthetic element, when an attempt to place it on the patient's tooth is inconclusive. In addition, and advantageously, the design method according to the invention allows a large reduction in the suffering of a patient having to undergo a dental restoration since the prosthetic element can be placed perfectly in a single session.

Advantageously, the design method according to the invention makes it possible to produce prosthetic elements having the aforementioned advantages at low cost for the patient since the steps of dental impressions and / or possible modifications of the prosthetic element produced on the basis of a size of the at least one tooth is no longer performed. An advantageous reduction in this cost is estimated to be one third of the amount of designing the same prosthetic element using techniques according to the prior art. For a crown, this cost is estimated at 300 €. The overall cost of a dental restoration attributable to the production of a prosthetic element is therefore very greatly reduced, thus making dental restorations more democratic for a disadvantaged clientele.

The design method according to the invention, and the underlying dental restoration process advantageously meet a growing societal need given the accelerated aging of certain populations, in particular in Europe, the USA, Canada or Asia. The

design method according to the invention makes it possible to quickly and efficiently produce prosthetic elements of high quality and perfectly adapted to the needs of each patient, thus meeting a growing demand for dental restoration while fully compensating for a shortage in nursing staff, in particular prosthetists or dental surgeons.

Advantageously, the design method according to the invention makes it possible to limit the ecological and environmental impact due to a relocation of a production of prosthetic elements. In fact, it is possible to carry out the design method according to the invention locally, in a laboratory or a dental office, to produce prosthetic elements at low cost, without having to resort to a manual hand. foreign and cheap work. In addition, since the design method is mainly digital, a step of verifying compliance with the safety and traceability standards specific to a prosthetic element can be attached.

An advantageous preferred embodiment of the invention is now presented, according to which step (iii) comprises the following sub-steps:

(111.1) determining a type of dental preparation based on said first computer file;

(111.2) algorithmically generating a dental protocol on the basis of the type of dental preparation determined in step (iii.1), said dental protocol consisting of a collection of digital data for geometrically parameterizing said three-dimensional representation of the volumetric reduction;

(111.3) validating and / or modifying said dental protocol on the basis of the comparison sub-step of step (i).

This preferred embodiment of step (iii) had been discussed above. It underlies a computer program that converts data on the type of dental preparation into a dental protocol studied experimentally so as to put all the inventor's experience at the service of the design of prosthetic elements. This embodiment advantageously facilitates the performance of step (iii) by minimizing the risks for a dental prosthetist with little experience of making a mistake. Very precious time in the execution of the method according to the invention is thus saved. More precisely and more preferably, step (iii.1) comprises the following sub-steps:

• visualize said intra-oral three-dimensional representation of a dentition;

• segmenting said intraoral three-dimensional representation of a dentition so as to obtain an isolated three-dimensional representation of the at least one tooth;

• algorithmically generate the vestibular, lingual, mesial, distal and occlusal faces of the at least one tooth by identifying a point on each of these faces at the level of the isolated three-dimensional representation of the at least one tooth;

• modify and / or validate the borders of said vestibular, lingual, mesial, distal and occlusal faces of the at least one tooth (91) by additions, displacements and / or withdrawals of points of these faces on the isolated three-dimensional representation of the at least one tooth;

• identifying a mark of at least one of said reference axes on the basis of the comparison sub-step of step (i), the mark comprising an insertion axis of the at least one tooth.

The type of dental preparation is thus determined with regard to digital manipulations of the intraoral three-dimensional representation making it possible to recognize the different faces of the tooth and to freeze a work mark on this three-dimensional representation. The practitioner can realize by these digital manipulations and thanks to the comparison sub-step of step (i) (having allowed an advantageous detection of elements of the dentition, periodontal tissues, soft and hard tissues, nerves, etc.) of the type of dental preparation (including volumetric reduction) that should be provided on the at least one tooth, and of the mark necessary to proceed with this dental preparation. These embodiments allow a synergistic effect of the advantages of steps (i) and (iii).

Preferably, following the segmentation sub-step, the interproximal periodontium is algorithmically taken into account in the dental protocol (by continuation according to a Bézier curve). This makes it possible, in step (iv), to take account of spaces to be filled consecutive to this segmentation sub-step.

The dental protocol is preferably in the form of a table of real numbers corresponding to the digital data which allow a geometric parameterization of the volumetric reduction according to advantageous (indirect) relationships forming an integral part of the invention. Preferably, the digital data includes:

for each face among the vestibular, lingual, mesial and distal faces of said at least one tooth:

• a ray ;

• height ;

corresponding to a parameterization of a transverse section of an elliptical fillet (optionally circular) of the face according to an elliptical arc (optionally of a circle) of semi-major axis corresponding to said radius measured essentially perpendicular to said axis of insertion and of semi-minor axis corresponding to said height measured substantially parallel to said insertion axis;

for each face among the vestibular, lingual, mesial and distal faces of said at least one tooth:

a first offset datum corresponding to a displacement of each point of the face on the isolated three-dimensional representation of the at least one tooth towards the insertion axis;

for the occlusal face of said at least one tooth:

first offset data corresponding to a displacement of each point of the occlusal face on the isolated three-dimensional representation of the at least one tooth along the insertion axis;

two percentages defining two zones consisting of marginal and median zones of said at least one tooth on the isolated three-dimensional representation of the at least one tooth, each percentage corresponding to the ratio between a height of one zone and a height of the two zones (that - this preferably corresponding to a visible dental crown height, the height of the dental root therefore not being included), these heights being measured essentially parallel to the axis of insertion;

for each of said zones:

• a volumetric reduction orientation angle measured with respect to the insertion axis;

• a minimum height.

The insertion axis is known to a person skilled in the art. It is directed from the marginal area towards an occlusal face of the at least one tooth, or, in other words, from the root towards the occlusal face of the at least one tooth, along the at least one tooth. The offset data preferably corresponds to a displacement towards the insertion axis of between 0.2 and 2.5 mm, more preferably between 0.4 mm and 1.5 mm, optionally about 1 mm. . The radius and the height are preferably between 0.5 and 1.5 mm, optionally these data are about 0.9 mm and therefore define a circular cross-section fillet on the buccal, lingual, mesial and distal faces. Preferably, the percentages are about 50%. Preferably, the orientation angle for the marginal zone is between 0 and 5 °, preferably it is about 2 °. Preferably, the angle of orientation for the middle zone is between 15 and 30 °, more preferably it is about 20 °. Optionally, the minimum height associated with each zone is approximately 0.1 mm.

More preferably, according to these preferred embodiments of the invention, the technical constraints include a minimum thickness of a design material for the prosthetic element, and the first face offset data depend on this minimum thickness. Account is thus advantageously taken of the reduction that each face must undergo to a minimum in order to be able to restore the at least one tooth by placing the prosthetic element, since the latter must have a certain minimum external wall thickness. It should be noted that this preferred embodiment is in no way limiting the case where the prosthetic element is a facet, for example, intended to be placed on one of the faces because in this case, approximately zero offset data may be provided. for the other faces,

Preferably, the first offset data is determined independently of the radii and heights associated with the fillets. This is important considering the fact that the first conical surface defined below in step (iv.2) starts from an end curve bordering the elliptical fillets and that a direct dependence on the first offset data would create points of rupture between these fillets and this first conical surface.

Advantageously and preferably, these preferred embodiments of step (iii) have an impact and direct application to step (iv). Preferably, this comprises a sub-step of algorithmic generation of a three-dimensional representation of a reduction.

volumetric of the at least one tooth. This sub-step preferably comprises the following sub-steps (therefore advantageously resulting from these preferred embodiments of step (iii)):

(iv.1) generating a marginal surface consisting of the elliptical fillets of the vestibular, lingual, mesial and distal faces of said at least one tooth;

(iv.2) generating a first conical surface around said insertion axis from an end curve bordering the marginal surface generated in sub-step (iv.1), this first conical surface extending parallel to said zone marginal and having an inclination towards the insertion axis by an angle corresponding to the volumetric reduction orientation angle of said marginal zone;

(iv.3) generating a second conical surface around said insertion axis from an end curve bordering the first conical surface generated in substep (iv.2), this second conical surface extending parallel to said middle zone and having an inclination towards the insertion axis by an angle corresponding to the volumetric reduction orientation angle of said middle zone;

(iv.4) calculate a second offset datum for each point of the marginal and median zones on the isolated three-dimensional representation of the at least one tooth, this second offset datum corresponding to a displacement of this point towards or against the insertion axis to move this point on one of the first or second conical surfaces;

• define a primary reduction surface by moving each point of the marginal and median zones towards the insertion axis according to:

the second offset datum for this point if it corresponds to a displacement towards the insertion axis and if it is greater than the first offset datum for this point,

the first offset data of this point otherwise; (iv.5) generate an occlusal surface from an extreme curve bordering the primary reduction surface generated in sub-step (iv.4) by a displacement of each point of the occlusal face on the isolated three-dimensional representation of the at least one tooth, along the insertion axis according to the first offset datum;

(iv.6) smooth and / or regularize a total surface consisting of the assembly of the marginal, reduction primary and occlusal surfaces, this total surface presenting a plane tangent to the total surface at an intersection with the perpendicular insertion axis to the insertion axis.

This preferred embodiment of step (iv) takes full advantage of the embodiments of step (iii). Thus, it suffices for the practitioner to perform step (iii.1) to algorithmically generate a three-dimensional representation of the volumetric reduction of the at least one tooth, thanks to the advantageous algorithmic steps (iii.2) and (iv.1 ) to (iv.6). In addition, it should be emphasized that this preferred embodiment of step (iv) allows a volumetric reduction adapted to the type of dental preparation which goes well beyond a simple automatic volumetric withdrawal per face. Indeed, the present invention is intended to provide a technical solution to the placement of a definitive prosthetic element and not one of coarse volumetric reduction for the place of a temporary prosthetic element.

Then evaluate, in sub-step (iv.4), that these tapered surfaces are suitable for placement of a prosthetic element according to the first offset data of the dental protocol. This operation is carried out point by point of isolated three-dimensional representation. Thus, the primary reduction surface obtained in step (iv.4) comprises both points of the conical surfaces and points determined by displacements according to the first offset data, so as to take account of both a simple and effective subsequent practice for the dentist, but also of all the dental protocol determined in step (iii.3).

Sub-step (iv.6) also plays an important role because it makes it possible to smooth and regularize the various junctions between the conical surfaces, the other portions of the primary surface, the marginal surface and the occlusal surface, preferably offering flatten and / or truncate a region of the occlusal surface at its intersection with the insertion axis (so that said tangent plane is perpendicular to the insertion axis), thus avoiding any irregularity at this level, and facilitating both the design of the prosthetic element and the subsequent volumetric reduction of the at least one tooth.

Preferably, the orientation angle for the marginal zone is between 0 and 5 °. The first conical surface is therefore approximately cylindrical. Preferably, the orientation angle for the middle zone is between 15 and 30 °. The second conical surface is therefore visually conical and its assembly with the first conical surface along the end curve bordering them forms a surface

generally cylindrical-conical. The latter is attached to the marginal surface formed by the leave of the vestibular, lingual, mesial and distal surfaces. This cylindrical-conical shape is very advantageous because it offers excellent anchoring and great stability to the prosthetic element to come, in particular preventing its tilting. Thanks to the parameters of the dental protocol and the succession of steps (iv.1) to (iv.6), the volumetric reduction obtained from the cylindrical-conical shape is also parameterized per face, which makes it possible to favor aesthetics. , the stability or the resistance of the prosthetic element to come depending on the face considered. For example, aesthetics may be preferred for a vestibular face, stability for a lingual (or palatal) face, etc. This applies to other sub-steps. For example, for the occlusal face, aesthetics and / or strength may also be favored, in particular by providing sufficient space for the material constituting the prosthetic element. A volumetric reduction of the occlusal face will preferably be tapered.

According to a preferred embodiment of the design method, this method further comprises the additional step:

(vii ') generate a fourth computer file on the basis of the second validated and / or modified computer file, the fourth computer file comprising instructions for machining the at least one tooth corresponding to the three-dimensional representation of the volumetric reduction of the at least a tooth.

This fourth computer file is preferably also a CAM (machining) file, generated on the basis of the second computer file in the same way as the third computer file is generated in step (vii), but taking full account of dental protocol for a size of the at least one tooth.

The fourth computer file has a great advantage over the second computer file to directly understand instructions

machining of the at least one tooth usable by an appropriate machining machine and / or a practitioner. It is thus easier to follow the machining instructions than to define a machining yourself from a CAD file representing the volumetric reduction of the at least one tooth. This fourth computer file constitutes a major computer element of the invention because it provides for the first time an exact machining of the at least one tooth making it possible to obtain a machined external surface of the at least one tooth corresponding exactly to the intrados of the prosthetic element. It is thus possible to avoid any empty space between the at least one cut tooth and the prosthetic element. The presence of such an empty space would be detrimental to the dental integrity of the patient because it would allow a proliferation of bacteria.

According to a preferred embodiment of the design method, it further comprises the following additional steps:

(vii ”) generate a fifth computer file on the basis of said second validated and / or modified computer file, said fifth computer file comprising information relating to the three-dimensional representation of the intrados of said prosthetic element obtained in step (vi), these information comprising instructions for machining a rigid raw material corresponding to said three-dimensional representation of the intrados of said prosthetic element;

(viii ”) machining a block of said rigid raw material on the basis of machining instructions from said fifth computer file, so as to produce a control key for machining said at least one tooth corresponding to machining according to said three-dimensional representation of the volumetric reduction of said at least one tooth.

This fifth computer file is preferably also a CAM file, optionally stereolithography or machining, generated on the basis of the second computer file in the same way as the third computer file is generated in step (vii). This new file makes it possible to advantageously design a control key for the practitioner during dental preparation. In fact, he can thus apply the check key to the at least one tooth so as to check whether its size does indeed correspond to the expected volumetric reduction (the latter defining the lower surface of the prosthetic element). Although machining techniques are mentioned for the production of the check key, a production thereof by three-dimensional printing techniques (and a reformulation of steps (vii ”) and (viii”) in this sense) would not depart from the scope of the invention in any way. Preferably, according to the embodiment comprising the production of a control key, the method further comprises the additional step of cutting the control key into slices parallel to a plane. Thus, the practitioner can remove sections of the key so as to more easily see the correspondence between its size and the expected volumetric reduction by sectional view. These slices are preferably carried out horizontally (according to the occlusal surfaces of the teeth) or vertically (according to the axis of insertion). according to the embodiment comprising producing a check key, the method further comprises the additional step of cutting the check key into slices parallel to a plane. Thus, the practitioner can remove sections of the key so as to more easily see the correspondence between its size and the expected volumetric reduction by sectional view. These slices are preferably carried out horizontally (according to the occlusal surfaces of the teeth) or vertically (according to the axis of insertion). according to the embodiment comprising producing a check key, the method further comprises the additional step of cutting the check key into slices parallel to a plane. Thus, the practitioner can remove sections of the key so as to more easily see the correspondence between its size and the expected volumetric reduction by sectional view. These slices are preferably carried out horizontally (according to the occlusal surfaces of the teeth) or vertically (according to the axis of insertion). the practitioner can remove slices from the key so as to more easily see the correspondence between its size and the expected volumetric reduction by sectional view. These slices are preferably carried out horizontally (according to the occlusal surfaces of the teeth) or vertically (according to the axis of insertion). the practitioner can remove slices from the key so as to more easily see the correspondence between its size and the expected volumetric reduction by sectional view. These slices are preferably carried out horizontally (according to the occlusal surfaces of the teeth) or vertically (according to the axis of insertion).

According to a preferred embodiment of the design method comprising steps (iv.1) to (iv.6), it further comprises the following additional steps:

(iv ') generate a sixth computer file on the basis of said first computer file and said dental protocol validated and / or modified in step (iii.3), the sixth computer file comprising three collections of machining instructions of a rigid raw material, each of these collections including machining instructions for creating a cavity in the rigid raw material corresponding to the isolated three-dimensional representation,

a first of the collections of instructions further comprising machining instructions for creating an at least partially conical access window around the cavity following the first and second conical surfaces, a second of the collections of instructions further comprising instructions for 'machining to create two upper access windows to the cavity bordering the mesial and distal faces of the cavity which correspond to the mesial and distal faces of said at least one tooth on the isolated three-dimensional representation,

a third of the collections of instructions further comprising instructions for machining a portion of the rigid raw material surrounding a middle zone of the cavity corresponding to the middle zone of said at least one tooth on the isolated three-dimensional representation, to create two sloping edges according to the volumetric reduction orientation angle of the middle zone;

(viii ') machining a first, a second and a third block of said rigid raw material respectively on the basis of the first, second and third collections of machining instructions of said sixth computer file, so as to produce three machining guides of said at least one tooth according to said three-dimensional representation of the volumetric reduction of said at least one tooth.

This sixth computer file is preferably also a CAM file, optionally of stereolithography or of machining. This new file makes it possible to advantageously design machining guides for the practitioner during dental preparation which are quite specifically adapted to allow the practitioner to reproduce the sub-steps of step (iv) and thus to obtain a (representation three-dimensional) volumetric reduction of the at least one tooth faithful to that validated and / or modified in step (v). The machining guides obtained from the first, second and third blocks are preferably to be used in this order so as to reproduce more or less directly certain substeps (or product of substeps) of step (iv) . Although machining techniques are mentioned for the production of the guides, a production thereof by three-dimensional printing techniques (and a reformulation of steps (iv ') and (viii') in this sense) would not depart from the scope of the invention in any way. The rigid raw material is preferably at least partly and / or at least locally transparent. Optionally, it is completely transparent. Optionally, it is at least partially colored. Preferably, it is locally transparent around the cavity to facilitate the visualization of the at least one tooth to be cut. Preferably, the guides also include markings including size instructions for the at least one tooth around the cavity. Preferably, according to the embodiment comprising a production of the guides, the method further comprises the additional step of securing at least one safety stopper and a positioning rail of a dental burr on the first, second and third blocks. Thus, handling errors are avoided during dental preparation by virtue of the guides very advantageously provided within the framework of the invention.

In the context of this document, a "prosthetic element" preferably refers to an element among: a crown, a bridge, a filling, an inlay, an onlay, a dental implant, a veneer, or a combination of several of these elements. . The term prosthetic element encompasses any type of fixed prosthesis, and any type of partially or completely removable prosthesis on at least one tooth and / or on at least one dental implant. Although part of this document is particularly illustrated on the basis of a dental restoration

comprising a design and / or placement of a crown, a dental restoration by means of another prosthetic element cannot depart from the scope of the invention. In the context of this document, the terms “intrados” and “extrados” of a prosthetic element refer respectively to an interior surface and an exterior surface of the prosthetic element, and are known to a person skilled in the dental prosthetist art. and / or dentist.

In the context of this document, the terms “dentist”, “dental surgeon”, or more generally “practitioner” are preferably used interchangeably. The practitioner responsible for capturing an intra-oral three-dimensional representation and / or a radiographic image is preferably a dentist. The practitioner responsible for the size of the at least one tooth is preferably a dentist or dental surgeon. A practitioner responsible for carrying out steps (ii) to (vii) is preferably a dental prosthetist, specialized in the digital design of prosthetic elements.

In the context of this document, the STL format is a computer file format known to a person skilled in the art. The abbreviation STL stands for “Standard Triangle Language” in English.

For the purposes of this document, a "fillet" is a clinical form of cervical borderline of a peripheral coronary preparation characterized by a slightly concave profile forming an obtuse angle of connection between the prepared coronary zone and the unprepared zone.

For the purposes of this document, the at least one tooth is optionally a tooth. In general, the method is applied successively to each tooth when there are several. The anatomy of the crown of a tooth is divided into five faces known to a person skilled in the art and say:

"occlusal" face which is the face on which you bite;

“vestibular” face which is the face on the outside, against the cheek;

“lingual” face (sometimes called distinctly the palatal face for the upper teeth) which is the face on the inside facing the palate and / or that the tongue usually touches;

“mesial” face which is the face hidden between two teeth closest to the median axis of the dental arch;

“distal” face which is the face hidden between two teeth furthest from the median axis of the dental arch.

The use, in this document, of the verb "to understand" of its variants, as well as its conjugations, can in no way exclude the presence of elements other than those mentioned. The use, in this document, of the indefinite article "a", "a", or of the definite article "the", "the" or "", to introduce an element does not exclude the presence of 'a plurality of these elements.

The invention also provides a prosthetic element produced by the design method according to the invention. All of the preferred embodiments as well as all of the advantages of the design method according to the invention are transposed mutatis mutandis to the present prosthetic element. In particular, the prosthetic element is preferably made of a bioceramic material to ensure biological compatibility with the soft and hard tissues, and the dentition of a patient, as well as a very long life of the prosthetic element.

The invention also provides a control key produced by the preferred embodiments of the design method comprising step (viii ”). All of the preferred embodiments as well as all of the advantages of these embodiments are transposed mutatis mutandis to the present control key. The invention also provides three machining guides produced by the preferred embodiments of the design method comprising step (viii '). All modes

preferred embodiments as well as all the advantages of these embodiments are transposed mutatis mutandis to the present guides. Preferably, the control key and / or the guides are made of rigid resin, preferably transparent.

The invention also provides tools for implementing the design method according to the invention: a set of devices, computer programs and media readable by a computer. These tools are detailed below.

The present invention provides:

a first computer program comprising first instructions which, when the first computer program is executed, lead to the implementation of step (iv) of the design method according to the invention;

a second computer program comprising second instructions which, when the second computer program is executed, lead to the implementation of step (vii) of the design method according to the invention;

a third computer program comprising third instructions which, when the third computer program is executed, lead to the implementation of the additional step (vii ') of the design method according to a very preferred embodiment of the invention;

a fourth computer program comprising fourth instructions which, when the fourth computer program is executed, lead to the implementation of the additional step (vii ”) of the design method according to a preferred embodiment of the invention ;

a fifth computer program comprising fifth instructions which, when the fifth computer program is executed, lead to the implementation of the additional step (iv ') of the design method according to a preferred embodiment of the invention ;

a sixth computer program comprising sixth instructions which, when the sixth computer program is executed, lead to the implementation of the additional step (iii.2) of the design method according to a preferred embodiment of the invention.

The invention also proposes a set of computer programs comprising the first and / or the second and / or the third and / or the fourth and / or the fifth and / or the sixth computer programs. The invention also provides a medium readable by a computer on which is recorded at least one computer program present in a set of computer programs according to the invention.

As detailed above, the first, second, third, fourth, fifth and sixth computer programs are at the heart of the design method according to the invention. They make it possible to partially automate the design of a prosthetic element, to digitally assist a prosthetist in the definition of the prosthetic element, and to intelligently plan its production. In particular, the embodiments associated with these programs as mentioned above as well as the advantages thereof relating to the associated steps (iii), (iv), (iv '), (vii), (vii') and ( vii ”) apply to programs and sets of programs, as well as to computer readable media.

The present invention provides a set of devices for designing a prosthetic element by performing the design method according to the invention, the set of devices comprising:

at least one imaging device for providing the first computer file of step (i) of the design method;

a computer system comprising:

• an interface to receive:

at least one technical parameter determined in step (iii) of the design method, and

validations and / or modifications of the second computer file of step (v) of the design method; and to visualize and / or communicate data on: the intra-oral three-dimensional representation and the radiographic image of the first computer file (1 1) supplied in step (i); and on three-dimensional representations:

the extrados of the prosthetic element obtained in step (ii); the volumetric reduction of the at least one tooth of the second computer file generated in step (iv);

the volumetric reduction of the at least one tooth of the second computer file validated and / or modified in step (v);

of the intrados of the prosthetic element obtained in step (vi);

• a logical unit to at least partially implement steps (ii), (iv), (vi) and (vii) of the design method; a production machine for reading the information from the third computer file generated in step (vii), and for implementing step (viii) of the design method.

It is clear that various advantages and preferred embodiments of the set of devices according to the invention can be deduced directly from all of the preferred embodiments as well as all of the advantages of the design method according to the invention. . In particular, the at least one imaging device preferably comprises at least one of: an intra-oral scanner and an X-ray radiography device. Preferably, the information of the third computer file consists of machining instructions for a material and the production machine includes a machining machine for reading the third computer file and executing these instructions. Such a machining machine is known to a person skilled in the art and the provision of instructions in a compatible computer file is the objective of step (vii). Preferably, the machining machine is able to design several prosthetic elements simultaneously. Preferably, the computer system comprises a computer of which a screen, a keyboard and a mouse are the interface and of which the processor and at least one readable medium on which is recorded at least one computer program among the first, second and / or third computer programs, define the logical unit. For suitable embodiments of the invention, the logic unit is also preferably also suitable for implementing the sub-step (iii.2) and the steps (iv '), (vii') and (vii ” ). a keyboard and a mouse are the interface and whose processor and at least one readable medium on which is recorded at least one computer program among the first, second and / or third computer programs, define the logical unit. For suitable embodiments of the invention, the logic unit is also preferably also suitable for implementing the sub-step (iii.2) and the steps (iv '), (vii') and (vii ” ). a keyboard and a mouse are the interface and whose processor and at least one readable medium on which is recorded at least one computer program among the first, second and / or third computer programs, define the logical unit. For suitable embodiments of the invention, the logic unit is also preferably also suitable for implementing the sub-step (iii.2) and the steps (iv '), (vii') and (vii ” ).

The present invention provides a computer readable medium on which is recorded a second computer file generated in step (iv) and / or validated and / or modified in step (v) of the design method according to the invention. The present invention also provides a computer readable medium on which is recorded at least one of a third computer file being generated in step (vii) of the design method according to the invention, and / or a fourth computer file being generated. in step (vii ') of the preferred embodiment of the design method according to the invention.

The advantages and preferred embodiments of these steps (iv), (v), (vii) and (vii '), as well as of the second, third and fourth computer files are transposed mutatis mutandis to the present computer readable media. Preferably, the computer readable medium on which the third computer file is recorded allows a physical transfer of the third computer file of a data center comprising a computer system as mentioned above for the execution of steps (ii) to (vii). ), and (vii ') of the design method, to a laboratory comprising a production machine for reading this third computer file and producing the prosthetic element. Of

Preferably, the computer-readable medium on which the fourth computer file is recorded allows a physical transfer of the fourth computer file from the computer data center, to a dental office or a medical center where a dentist can read it by computer in order to obtain information machining instructions for the at least one tooth to be executed.

The present invention also provides a computer readable medium on which is recorded at least one of a fifth computer file being generated in step (vii ”) of the design method according to the invention, and / or a sixth computer file being generated in step (iv ') of the preferred embodiment of the design method according to the invention.

The advantages and preferred embodiments of these steps (iv ') and (vii ”), as well as of the fifth and sixth computer files are transposed mutatis mutandis to the present computer readable media. Preferably, this computer readable medium allows a physical transfer of the fifth and / or sixth computer files of a data center comprising a computer system as mentioned above for the execution of steps (ii) to (vii), (iv ') and (vii ”) of the design method, to an industrial zone comprising a production machine for reading this fifth and / or sixth computer file and producing the control key and / or the machining guides.

An example of a system for assisting an operator in a placement of a prosthetic element designed by the design method is now introduced below, preferably fully exploiting step (vii ') of the method according to the invention. This system could be the subject of an invention as such independently of the invention which is presently claimed. The operator assistance system in a dental restoration that is proposed within the scope of this document includes:

a robot provided with a mobile robotic arm and integral with a machining tool placed at one end of the robotic arm;

a robot spatial guidance system comprising:

• a first spatial reference fixed to the robotic arm;

• a second spatial landmark configured to be attached to a point in an operating area;

• a detector configured to determine a first distance separating the detector from the first spatial frame, and a second distance separating the detector from the second spatial frame;

• a logical computer unit configured for:

read a computer file comprising machining instructions for at least one tooth,

receive data relating to the first and second distances, and

determining information for comparing the data with the machining instructions;

a communication tool digitally connected to the computer unit to communicate the comparison information to the operator.

This assistance system advantageously allows an operator, preferably a dentist and / or dental surgeon, to cut at least one tooth without technical errors.

Indeed, the communication tool makes it possible to communicate to the operator comparison information determined by the logical computer unit between, on the one hand, instructions for machining the at least one tooth of a computer file, and on the other hand, a relative position between the robotic arm of the robot and an operating zone, via spatial reference marks from which a distance separating them is evaluated by means of the detector. In this way, deviations between the predetermined machining instructions and the actual machining action via a robotic arm position can be accounted for. The operator thus obtains a report of his actions by means of the robot in order to follow the machining instructions exactly and to obtain a precise size without technical errors.

The guidance system is an essential component of the assistance system because without it, it is impossible to associate a robot action and a machining instruction while fully taking into account the possible variation in the patient's position and an attached mark. to the area of ​​operation. Preferably, the guidance system makes it possible to inform the operator and / or the robot in real time of a compensatory movement to be performed with respect to a movement of a patient, for example, due to his breathing, to movements of the patient. maxilla or mandible.

Preferably, in general, the term “operating area” should be understood to mean a small area of ​​a patient's mouth comprising at least one tooth to be restored.

Preferably, the robot is digitally connected to the logical computer unit, so that the latter is able to control an execution of the machining instructions by means of the machining tool. Thus, and very advantageously, the robot can automatically proceed to size the at least one tooth according to the machining instructions. The robot is nevertheless preferably semi-automatic in the sense that it guides the operator in performing the size of the at least one tooth. Thus, it assists the operator, for example, by guiding him by a movement and / or a rotation and / or a vibration of the robotic arm, or even by automatically stopping the machining tool in the event of leaving the zone of. operation harmful to the physical integrity of a patient.

Advantageously, the robot allows unequaled precision alone by the operator of the order of 20 microns, as well as a reduction of an intervention time for the size of the at least one tooth of the order of 40 to 60. %. Advantageously, the assistance system therefore allows the operator to cut at least one tooth with great precision and without mental or physical fatigue. In the context of this document, the at least one tooth optionally generally comprises at least ten teeth, and / or at least twenty-four teeth of a patient. The assistance system advantageously allows the operator to restore such a large number of teeth, in one session, without fatigue.

Preferably, the operator interacts with the robotic arm, in the sense that the robotic arm is also able to be guided to a certain extent by the operator, for example to be brought into the operating area. The operator also preferably has an action for activating and deactivating the machining tool and / or the robot. In combination with the previous preferred embodiment, the robotic arm can thus be brought into the operating area by the operator, then work semi-autonomously under execution control of the machining instructions by the operator. logical computer unit. Advantageously, this double interaction of the robotic arm with the operator allows great flexibility, great safety and great precision, for the operator in a dental restoration operation.

Preferably, the machining tool is a dental bur and the term machining refers to milling.

Preferably, the robot comprises six bearings in order to undergo partial rotations around six axes. It includes wheels to move on a floor of a dental office.

The computer file in question preferably consists of a fourth computer file generated in step (vii ') according to the very preferred embodiment of the design method according to the invention.

In particular, in this case, the assistance system allows the operator to take into account the overall dentition and the hard and soft tissues of a patient, the size of the at least one tooth thus being perfectly adapted to the needs of the patient. patient and to a prosthetic element previously designed by carrying out the design method according to the invention. The assistance system therefore makes it possible to implement a dental restoration process defined previously in this summary and from which the advantages are transposed to the present assistance system, the computer file is such a fourth computer file.

According to a preferred embodiment of the assistance system, the communication tool comprises a screen for displaying in real time, at least partially, the operating zone and the machining tool. Preferably, the comparison information further comprises a position and / or an orientation of the machining tool in the operating area.

Such a communication tool makes it possible to guide the operator in a dental preparation for a dental restoration, for example, by virtually guiding a manipulation to be performed on the screen or by proposing several positions and / or orientation of the tool. machining in the operation area, or even several possible paths of the machining tool in the operation area determined virtually via the logical computer unit on the basis of the computer file.

Optionally, the second spatial reference comprises at least one of:

an upper part comprising a helmet and / or at least one strap suitable for being placed around a forehead of a patient;

a lower part comprising a chin bar adapted to enclose a chin of a patient;

and second target symbols detectable by the detector attached to the upper part and / or the lower part.

More optionally, the second spatial reference comprises the lower and upper parts. Advantageously, the second spatial reference makes it possible to individually identify an upper jaw and

a lower jaw of a patient. Indeed, the upper part follows the movements of the upper jaw coupled to the forehead, while the lower part follows the movements of the lower jaw coupled to the chin. In addition, this second spatial landmark can advantageously optionally be used for a class of patient.

Optionally, according to a new embodiment of the second spatial mark, the latter comprises a rigid patient cheek retractor capable of forcing a stiffening of a patient's mouth, allowing access to the operating area, comprising second target symbols on an upper portion and on a lower portion, these symbols being able to be detected by the detector. This new optional embodiment also makes it possible to locate the lower and upper jaws of a patient via the detector.

According to a preferred embodiment of the assistance system, the first spatial mark comprises first target symbols detectable by the detector; and the second spatial mark comprises: a dental part capable of at least partially conforming to a shape of a portion of a dentition included in the operating zone;

a protruding member comprising second target symbols detectable by the detector, the protruding member being configured to be attached to the dental part by means of a fastening system, so as to extend outside the area of ​​operation.

Advantageously, such a second spatial reference allows the use of a dental part specific to the dentition of each patient, while the protruding element can be reused from one patient to another and attached by means of the attachment system on a dental part. Another advantage of the dental part is that it at least partially conforms to a shape of the portion of the dentition in the operating area, so that the whole of the second spatial mark is more stable by

relative to the patient's landmark, which is essential for the purpose of the robot's spatial guidance system. A second spatial cue of another type, for example, based on target symbols that would be stuck on teeth of the dentition is also possible. Nevertheless, the protruding characteristic of the protruding element is advantageous because this element extends outside the operating zone, which facilitates the detection of the second target symbols by the detector.

According to a particular embodiment, the dental part is of a semi-cylindrical shape. The dental part then constitutes a substantially curved gutter suitable for being placed on the dentition.

Preferably, the dental part comprises a partial dental impression designed from an intra-oral three-dimensional representation of the dentition, more preferably by means of an intra-oral scanner. More preferably, according to the preferred embodiment for which the computer file is a fourth computer file obtained according to a step (vii ') of the design method, the intraoral three-dimensional representation is that provided in step (i). Given the temporary use of the dental part, it can be made of a material less resistant than the prosthetic element, and for example, by means of machining techniques or additive manufacturing processes such as a three-dimensional impression.

Independently of this semi-automated implementation, as specified above, the invention also provides devices for assisting a dentist and / or dental surgeon in the operation of the size of the least one tooth by reducing the risk of technical errors. In this context, the practitioner is completely in control of the practice of dental trimming, without any assistance by a robot, but he can nevertheless control and / or guide it by the control key and / or the guides according to the invention. .

Brief description of the figures

Other characteristics and advantages of the present invention will become apparent on reading the detailed description which follows, for the understanding of which reference is made to the appended figures, among which:

FIG. 1 illustrates a schematic view a flowchart of a method of designing a prosthetic element according to a preferred embodiment of the invention;

FIG. 2 illustrates a schematic view of an implementation of a dental restoration method comprising a method of designing a prosthetic element according to a preferred embodiment of the invention;

FIG. 3 illustrates a simplified perspective view of a dentistry room equipped with a system for assisting an operator in a dental restoration described in the summary;

Figure 4 illustrates a three-dimensional view of elements of a robot and of a robot spatial guidance system described in the summary; FIG. 5 illustrates a three-dimensional view of a control key according to the invention;

FIG. 6 illustrates a three-dimensional view of a use of the control key illustrated in FIG. 5;

FIGS. 7 to 9 illustrate a top view of the guides according to the invention;

FIG. 10 illustrates a three-dimensional view of the use of a guide according to the invention;

FIG. 11 illustrates a schematic view of an implementation of steps (iv.1) to (iv.6) of a method for designing a prosthetic element according to a preferred embodiment of the invention;

FIG. 12 illustrates a particular application of steps (iv.1) to (iv.6) of a design method according to a preferred embodiment of the invention.

The drawings of the figures are not to scale. Generally, like elements are denoted by like references in the figures. In the context of this document, identical or similar elements may bear the same references. Furthermore, the presence of reference numbers or letters in the drawings cannot be considered as limiting, including when these numbers or letters are indicated in the claims.

Detailed description of particular embodiments of the invention

The present invention is described with particular embodiments and references to figures but the invention is not limited by them. The drawings or figures described are only schematic and are not limiting.

Figures 1 and 2 illustrate at least partially an implementation of a method of dental restoration of a tooth 91 of a dentition 92 of a patient P comprising a method of designing a prosthetic element 1 according to a method of preferred embodiment of the invention. Reference is made below to the notations (i), (ii), (iii), ... of the various stages of the design method introduced in the summary of the invention as well as in the claims.

It is assumed that the patient P is to undergo a dental restoration comprising a milling of the tooth 91 and the placement of a prosthetic element consisting of a crown 1 on the milled tooth 91. The design method according to the invention is applied to the crown 1 to be designed. This method makes it possible, according to a preferred embodiment, to be completed so as to be able to easily and quickly restore tooth 91 of patient P.

For this, the method offers the patient P to go to a three-dimensional imaging center 81 and to undergo an intra-oral scan of his dentition 92 by means of an intra-oral scanner 2, so as to perform the procedure. 'step (i), that is to say, providing a first computer file 1 1 comprising an intraoral three-dimensional representation of the dentition 92 comprising the tooth 91 to be restored by means of the crown 1. The imaging center three-dimensional 81 is, preferably, one of: a dental office, a medical center, or even a nearby imaging center. Advantageously, such a scan takes less than five minutes to be performed; after this time, patient P is released. It is preferably supplemented by a two-dimensional panoramic radiographic image of the mouth and / or of the dentition 92 of the patient P, and which is either attached to the first computer file 1 1, or supplied simultaneously to the first computer file 1 1 in another first computer file 1 1 '. The panoramic radiographic image is preferably captured by means of an X-ray machine. It can provide more information on the structure of the dentition 92 of the patient P, on the nerves, associated soft and hard tissues, and this in particular by a comparison of the intra-oral three-dimensional representation with the radiographic image.

The first computer file 1 1 is then sent, via a computer readable medium and / or via a shared data cloud, to a data center 82 comprising a computer system 3 allowing execution of steps (ii) to (vii), and (vii ') of the design method according to the preferred embodiment of the invention, in the order illustrated in FIG. 1, and as detailed in the summary of the invention. A dental prosthetist and / or a specialized CAD designer process the first computer file 11 to determine a representation of the crown 1, the latter comprising three-dimensional representations 1 A and 1 B respectively of its upper surface and its lower surface, obtained from after the

steps (ii) and (vi) respectively. This representation is included in one or more computer files of STL format of CAD type designed at least partially by means of a first computer program according to the present invention. A second and a third computer programs according to a preferred embodiment of the invention make it possible to use dental and prosthesis protocols to generate a third 13 and a fourth 14 CAM type computer files which include machining instructions. respectively of a ceramic material to form the crown 1, and tooth 91 to adapt to the intrados 1B of the crown 1 during placement.

The third computer file 13 is then sent, via a computer readable medium and / or via a shared data cloud, to a laboratory 83 comprising a machining machine 4 allowing execution of step (viii) of the method of design according to the preferred embodiment of the invention. In particular, the machining machine 4 reads the third computer file 13 and executes the machining instructions so as to machine the ceramic material to form the crown 1, the upper surface and the lower surface of the crown 1 consisting of surfaces of a shape corresponding to the three-dimensional representations 1A and 1 B.

The fourth computer file 14 is, for its part, sent, via a computer readable medium and / or a shared data cloud, to a dental office 84 of a surgeon practitioner and / or dentist D equipped with a system of assistance 5 as described in the summary. It should be noted that a practitioner D having such a machining machine 4 in the dental office 84 can receive the third computer file 13 and himself produce the crown 1 which he needs. In particular, the locations 81, 83 and 84 are likely to coincide.

The practitioner D, having the fourth computer file 14, then performs the dental restoration operation by milling tooth 91 and fixing crown 1 on the milled tooth. This operation is well known, but it can be significantly improved in the context of the invention because the tooth 91 is milled with the help of the assistance system 5 described in the summary and so as to adapt to the crown 1. already designed, and not the other way around. Thus, the operation is of an advantageous duration of less than thirty minutes and the patient P 'finds a smile on leaving the dental office.

The process leading to the dental restoration is now described with reference to FIG. 3 showing a simplified view of an operating room of the dental office 84 equipped with an assistance system 5 as described in the summary. The elements of the dental office 84 shown in Figure 2 are all illustrated in Figure 3. The room includes conventional technical tools of the practitioner D such as a seat 84A to accommodate the patient P, a station 84B including a water supply and a tower carrying a lamp 84C placed in height, and a movable arm extending around the seat 84A, and to which is mechanically coupled a pallet 84D of standard instruments of the practitioner D. The assistance system 5 comprises a robot 6 movable around from seat 84A, in an 80R zone. It is equipped with wheels to ensure this mobility. It is also provided with a robotic articulated arm 61 mobile and integral with a machining tool consisting of a milling cutter 62 placed at one end of the robotic arm 61. The assistance system 5 also comprises a spatial guidance system for the robot. 6 comprising a detector 73, preferably fixed to a support for the lamp 84C, overhanging the seat 84A. As shown in Figure 4, detector 73 is configured to determine:

a first distance separating one of its points from at least one of the first target symbols 74 from a first spatial frame 71 fixed to the robotic arm 61;

a second distance separating one of its points from at least one of second target symbols 77 from a second spatial frame 72 which is attached to a point of an operating zone of the dentition 92.

while discarding the dental part 75 after use. Preferably, the dental part is designed of a solid and inexpensive material from the first computer file 1 1 and this to constitute a partial dental impression which perfectly matches the portion of the dentition 92. The dental part 75 is, for example, designed by an additive manufacturing process. It is necessary to design the protruding member as extending out of the operating area to facilitate visibility of the second target symbols 77 by the detector 73 while ensuring that the second spatial cue 72 reflects the movements of the patient P relatively. to a fixed reference point in the room and to the robotic arm 61.

read the fourth computer file 14,

receiving data relating to the first and second distances from detector 73, and

determining information for comparing the data with the machining instructions of the fourth computer file 14,

controlling and / or stopping the robot 6 and / or the cutter 62 according to the comparison information.

The assistance system 5 also comprises a communication tool 51 digitally connected to the computer unit 52 and comprising a screen for communicating the comparison information to the practitioner D. Thus, and as detailed in the summary of the invention, the practitioner D can be guided in his milling by the assistance system 5 so as to guarantee high reliability and high speed of the operation, as well as high precision in the milling, and in particular, obtaining a surface of the milled tooth 91 corresponding exactly to the intrados of the crown 1 to be placed. Optionally, the robot 6 comprises another movable mechanical arm comprising another detector 73 'of a structure and for use similar to the detector 73. Optionally,

The process leading to the dental restoration described with regard to FIGS. 3 and 4 is advantageously (semi) automated using the assistance system 5 as described in the summary. However, this assistance system 5 is likely to be expensive and complex to implement. It is therefore proposed, in the context of the invention, inexpensive and very advantageous alternatives of control key and guides for machining the at least one tooth 91. This control key 100 and these guides 110, 120 and 130 are introduced precisely in the summary of the invention and illustrated in Figures 5 to 10. The check key 100 is formed from a block of rigid raw material which is machined through embodiments of the invention, so that the three-dimensional representation of the lower surface 1 B of the prosthetic element 1 is formed from a lower face of the block. Preferably, three-dimensional representations of neighboring teeth 91 A and 91 B are also machined in a similar fashion. The control key 100 therefore acts as a mold which can be placed on the dentition 92 of the patient when the at least one tooth 91 has been prepared by a practitioner. The check key 100 thus enables the practitioner to realize any errors in the size of the at least one tooth 91. To facilitate this, the check key 100 is cut into slices 101 parallel to a plane (vertical in the case of illustrated, but which could just as well be horizontal). In this way, the practitioner can move certain sections 101 so as to observe the evolution of its size and its good correspondence with the lower surface 1 B of the prosthetic element 1. This is in particular illustrated in FIG. 6. The guides 1 10, 120 and 130 are for their part directly associated with the practice of machining the at least one tooth 91 with regard to the method comprising steps (iv.1) to (iv.6) as explained in the summary of the invention. They are shown seen from above (downstream of the insertion axis when they are arranged on the at least one tooth 91) in Figures 7 to 9 and are obtained respectively by the application of the first, second and third collections of Machining instructions to the first, second and third blocks of a transparent rigid raw material, as explained in the summary of the invention. Each comprises a cavity 91 'in this raw material corresponding to the isolated three-dimensional representation of the at least one tooth 91 which is obtained by step (iii.1). Windows 1 1 1, 121 and 132 are formed respectively in the guides 1 10, 120 and 130 to have access to this cavity 91 'in directions and angles of attack for the tooth size adapted to best reproduce certain sub-steps or results resulting from substeps of step (iv). The guide 130 is machined so that two sloping edges 131 are created giving a roof shape to this portion of the block of raw material, the slopes being determined according to an orientation angle of volumetric reduction of the middle zone of the at least one. a tooth 91 included in the dental protocol according to step (iii). The placement of such a guide 1 10 during dental preparation is illustrated in Figure 10. These guides 1 10, 120, 130 guide the machining of the at least one tooth 91 to reproduce in particular the primary surface according to the sub- step (iv.4). Other such guides can be deduced from the sub-steps of step (iv) without departing from the scope of the invention.

The decomposition of step (iv) into sub-steps (iv.1) to (iv.6) is commented on in the summary of the invention and illustrated in FIG. 11 with regard to a crown, this choice being non-limiting because these sub-steps apply effectively to the case of other prosthetic elements 1, since these influencing a choice of insertion axis Z by the dental protocol according to step (iii.1) to ( iii.3). Thus, this figure makes it possible to illustrate these sub-steps according to the following references. The elliptical fillets 201 are generated in substep (iv.1) at the marginal level of the at least one tooth 91, the first conical surface 202 (the latter being approximately cylindrical) is generated in step (iv.2. ) around the marginal area of ​​the at least one tooth 91, the second conical surface 203 is generated in step (iv. 3) around the middle zone of the at least one tooth 91, step (iv) compares the tapered surfaces 202 and 203 with an offset surface which would be obtained by moving each point of the marginal and middle zones towards the Z insertion axis according to the first offset data from the dental protocol. Indeed, it is possible for particular teeth that points of the conical surfaces 202 and 203 are outside the (three-dimensional representation of the) at least one tooth 91, so that it would no longer make sense to define a reduction. volumetric of the at least one tooth 91 on this basis. This is illustrated in Figure 12 in particular. It is therefore necessary to project these points inside the (three-dimensional representation of the) at least one tooth 91. This projection must be done while taking into account that it will be necessary in a way "to enter sufficiently far" in the (three-dimensional representation of the) at least one tooth 91 to guarantee enough room for the prosthetic element 1, since this one has a certain thickness. This is the whole point of the first offset data which derives from the dental protocol and somehow preferably encodes this minimum thickness which should be removed from each face of the at least one tooth 91 in order to be able to place the element. prosthetic 1 taking into account the tolerances associated with it. Thus step (iv.4) proposes this advantageous and judicious correction of the conical surfaces 202 and 203 to make it possible to define a suitable primary reduction surface for carrying out the volumetric reduction of the at least one tooth 91. Next,

In summary, the invention relates to a method of designing a prosthetic element 1 which can be executed prior to a size of a tooth 91 of a patient for the fitting of the prosthetic element 1.

The present invention has been described in relation to specific embodiments, which have a purely illustrative value and should not be considered as limiting. In general, it will appear obvious to a person skilled in the art that the present invention is not limited to the examples illustrated and / or described above. The invention comprises each of the new characteristics as well as all their combinations.

Claims

1. Method of designing a prosthetic element (1) comprising the following steps:

(i) · provide a first computer file (1 1) comprising:

an intraoral three-dimensional representation of a dentition (92) comprising at least one tooth (91) to be restored by means of said prosthetic element (1); an x-ray image of said dentition (92);

• identify common reference axes on said intraoral three-dimensional representation and on said radiographic image;

• comparing said intraoral three-dimensional representation with said radiographic image, this comparison sub-step comprising a superposition of said common reference axes;

(ii) determining a three-dimensional representation of an upper surface (1A) of said prosthetic element (1) on the basis of said first computer file (1 1);

(iii) determine technical parameters including:

a dental protocol, and / or

a type of dental preparation, and / or technical constraints,

on the basis of said first computer file (1 1), at least one of said technical parameters being determined on the basis of the comparison sub-step of step (i);

(iv) generating a second computer file comprising a three-dimensional representation of a volumetric reduction of said at least one tooth (91) on the basis of said technical parameters;

(v) validate and / or modify said second computer file; (vi) obtaining a three-dimensional representation of an intrados (1 B) of said prosthetic element (1) on the basis of said second validated and / or modified computer file;

(vii) generating a third computer file (13) comprising information relating to the three-dimensional representations of said upper surface (1A) and lower surface (1 B) of said prosthetic element (1);

(viii) producing said prosthetic element (1) on the basis of said third computer file (13).

2. Method according to the preceding claim, characterized in that step (ii) comprises the following sub-steps:

(11.1) choosing a model three-dimensional representation of a model dentition in a database on the basis of said first computer file (1 1);

(11.2) choosing an area of ​​the model three-dimensional representation corresponding to an area of ​​the intraoral three-dimensional representation corresponding to said at least one tooth (91);

(11.3) validating and / or modifying the zone of the model three-dimensional representation on the basis of said first computer file (1 1);

(11.4) define the three-dimensional representation of the upper surface (1A) of said prosthetic element (1) from the validated and / or modified zone of the model three-dimensional representation.

3. Method according to any one of the preceding claims, characterized in that step (iii) comprises the following sub-steps:

(111.1) determining a type of dental preparation on the basis of said first computer file (1 1);

(111.2) algorithmically generating a dental protocol on the basis of the type of dental preparation determined in step (iii.1), said dental protocol consisting of a collection of digital data for geometrically parameterizing said three-dimensional representation of the volumetric reduction;

(111.3) validating and / or modifying said dental protocol on the basis of the comparison sub-step of step (i).

4. Method according to the preceding claim,

characterized in that the sub-step (iii.1) comprises the following sub-steps:

• visualize said intra-oral three-dimensional representation of a dentition (92);

• segmenting said intraoral three-dimensional representation of a dentition (92) so as to obtain an isolated three-dimensional representation of the at least one tooth (91);

• algorithmically generate the vestibular, lingual, mesial, distal and occlusal faces of the at least one tooth (91) by identifying a point on each of these faces at the level of the isolated three-dimensional representation of the at least one tooth (91) ;

• modify and / or validate the borders of said vestibular, lingual, mesial, distal and occlusal faces of the at least one tooth (91) by additions, displacements and / or withdrawals of points of these faces on the isolated three-dimensional representation of the at least one tooth (91);

• identifying a mark of at least one of said reference axes on the basis of the comparison sub-step of step (i), the mark comprising an axis of insertion of the at least one tooth (91).

5. Method according to the preceding claim, characterized in that the digital data comprises:

- for each face among the vestibular, lingual, mesial and distal faces of said at least one tooth (91):

• a ray ;

· height ;

corresponding to a parameterization of a transverse section of an elliptical fillet of the face according to an elliptical arc of semi-major axis corresponding to said radius measured essentially perpendicular to said insertion axis and of semi-minor axis corresponding to said measured height essentially parallel to said axis of insertion;

- for each face among the vestibular, lingual, mesial and distal faces of said at least one tooth (91):

a first offset datum corresponding to a displacement of each point of the face on the isolated three-dimensional representation of the at least one tooth towards the insertion axis;

- for the occlusal face of said at least one tooth (91):

first offset data corresponding to a displacement of each point of the occlusal face on the isolated three-dimensional representation of the at least one tooth along the insertion axis;

- two percentages defining two zones consisting of marginal and middle zones of said at least one tooth (91) on the isolated three-dimensional representation of the at least one tooth (91), each percentage corresponding to the ratio between a height of a zone and a height of the two zones, these heights being measured essentially parallel to the axis of insertion;

- for each of said zones:

• a volumetric reduction orientation angle measured with respect to the insertion axis;

• a minimum height.

6. Method according to the preceding claim, characterized in that the technical constraints include a minimum thickness of a design material of the prosthetic element (1), and in that the first data for the offset of the faces depend on this minimum thickness. .

7. Method according to any one of the two preceding claims, characterized in that step (iv) comprises a sub-step of algorithmic generation of a three-dimensional representation of a volumetric reduction of said at least one tooth (91). , this sub-step comprising the following sub-steps:

(iv.1) generating a marginal surface consisting of the elliptical fillets (201) of the vestibular, lingual, mesial and distal faces of said at least one tooth (91);

(iv.2) generating a first conical surface (202) around said insertion axis (Z) from an end curve bordering the marginal surface generated in sub-step (iv.1), this first conical surface s 'extending parallel to said marginal zone and having an inclination towards the axis

inserting an angle corresponding to the volumetric reduction orientation angle of said marginal area;

(iv.3) generating a second conical surface (203) around said insertion axis from an extreme curve bordering the first conical surface generated in substep (iv.2), this second conical surface extending parallel to said middle zone and having an inclination towards the insertion axis by an angle corresponding to the orientation angle of volumetric reduction of said middle zone;

(iv.4) calculate a second offset datum for each point of the marginal and median zones on the isolated three-dimensional representation of the at least one tooth, this second offset datum corresponding to a displacement of this point towards or against the insertion axis to move this point on one of the first or second conical surfaces;

• define a primary reduction surface by moving each point of the marginal and median zones towards the insertion axis according to:

the second offset datum for this point if it corresponds to a displacement towards the insertion axis and if it is greater than the first offset datum for this point,

the first offset data of this point otherwise; (iv.5) generate an occlusal surface (204) from an extreme curve bordering the primary reduction surface generated in sub-step (iv.4) by a displacement of each point of the occlusal face on the three-dimensional representation isolated from the at least one tooth, along the insertion axis according to the first offset datum;

(iv.6) smooth and / or regularize a total surface (205) consisting of the assembly of the marginal, reduction primary and occlusal surfaces, this total surface having a plane tangent to the total surface at an intersection with the axis d insertion perpendicular to the insertion axis.

8. Method according to any one of the preceding claims, characterized in that:

said second computer file consists of an editable STL format file;

step (v) comprises validation and / or modification of each of the geometric parameters relating to said three-dimensional representation of the volumetric reduction of said at least one tooth (91) in a set of admissible values ​​defined beforehand by at least one of said technical parameters determined in step (iii).

9. Design method according to any one of the preceding claims characterized in that:

said information of said third computer file (13) comprises instructions for machining a material; step (viii) comprises a sub-step of machining said material on the basis of said machining instructions.

10. A design method according to any preceding claim, further comprising the additional step:

(vii ') generating a fourth computer file (14) on the basis of said second validated and / or modified computer file, said fourth computer file (14) comprising instructions for machining said at least one tooth (91)

corresponding to said three-dimensional representation of said volumetric reduction of said at least one tooth (91).

1 1. Design method according to any one of the preceding claims, further comprising the following additional steps:

(vii ”) generate a fifth computer file on the basis of said second validated and / or modified computer file, said fifth computer file comprising information relating to the three-dimensional representation of the lower surface (1 B) of said prosthetic element (1) obtained at l 'step (vi), this information comprising instructions for machining a rigid raw material corresponding to said three-dimensional representation of the intrados (1 B) of said prosthetic element

(1):

(viii ”) machining a block of said rigid raw material on the basis of the machining instructions of said fifth computer file (13), so as to produce a control key (100) of a machining of said at least one tooth (91) corresponding to machining according to said three-dimensional representation of the volumetric reduction of said at least one tooth (91).

12. Design method according to the preceding claim, characterized in that it further comprises the additional step of cutting the control key (100) into slices (101) parallel to a plane.

13. The design method of claim 7, further comprising the following additional steps:

(iV) generating a sixth computer file based on said first computer file (1 1) and said dental protocol validated and / or modified in step (iii.3), the sixth computer file comprising three collections of machining instructions of a rigid raw material, each of these collections comprising machining instructions for creating a cavity (91 ') in the rigid raw material corresponding to the isolated three-dimensional representation,

a first of the collections of instructions further comprising machining instructions for creating an at least partially conical access window (1 1 1) around the cavity (91 ') following the first and second conical surfaces, a second of the collections instructions further comprising machining instructions for creating two upper access windows (121) to the cavity (91 ') bordering mesial and distal faces of the cavity which correspond to the mesial and distal faces of said at least one tooth (91) on the isolated three-dimensional representation,

a third of the collections of instructions further comprising instructions for machining a portion of the rigid raw material surrounding a middle zone of the cavity corresponding to the middle zone of said at least one tooth (91) on the isolated three-dimensional representation, to create two sloping edges (131) according to the volumetric reduction orientation angle of the middle area;

(viü ') machining a first, a second and a third block of said rigid raw material respectively on the basis of the first, second and third collections of machining instructions of said sixth computer file, so as to produce three guides (1 10, 120 , 130) machining the at least one tooth

(91) according to said three-dimensional representation of the volumetric reduction of the at least one tooth (91).

14. Design method according to the preceding claim, characterized in that it further comprises the additional step of securing at least one safety stop and a positioning rail of a dental burr on the guides (1 10, 120, 130).

15. A set of devices for designing a prosthetic element (1) by performing the design method according to any one of the preceding claims, the set of devices comprising: at least one imaging device (2) for providing the first computer file of step (i) of the design method; a computer system (3) comprising:

• an interface to receive:

at least one technical parameter determined in step (iii) of the design method, and

validations and / or modifications of the second computer file of step (v) of the design method;

and to visualize and / or communicate data on: the intra-oral three-dimensional representation and the radiographic image of the first computer file (1 1) supplied in step (i);

the three-dimensional representation of the upper surface (1A) of said prosthetic element (1) obtained in step (ii); the three-dimensional representation of the volumetric reduction of the at least one tooth (91) of the second computer file generated in step (iv);

the three-dimensional representation of the volumetric reduction of the at least one tooth (91) of the second computer file validated and / or modified in step (v); the three-dimensional representation of the intrados (1 B) of said prosthetic element (1) obtained in step (vi);

• a logical unit to at least partially implement steps (ii), (iv), (vi) and (vii) of the design method;

a production machine (4) for reading the information from the third computer file (13) generated in step (vii), and for implementing step (viii) of the design method.

16. Set of computer programs comprising:

a first computer program comprising first instructions which, when said first computer program is executed, lead to the implementation of step (iv) of the design method according to any one of claims 1 to 14; and

a second computer program comprising second instructions which, when said second computer program is executed, lead to the implementation of step (vii) of the design method according to any one of claims 1 to 14.

17. A set of computer programs according to the preceding claim, further comprising:

a third computer program comprising third instructions which, when said third computer program is executed, lead to the implementation of

the additional step (vii ') of the design method according to claim 10; and or

a fourth computer program comprising fourth instructions which, when said fourth computer program is executed, lead to the implementation of the additional step (vii ”) of the design method according to any one of claims 1 1 or 12; and or

a fifth computer program comprising fifth instructions which, when said fifth computer program is executed, lead to the implementation of the additional step (iv ') of the design method according to any one of claims 13 or 14 ; and or

a sixth computer program comprising sixth instructions which, when said sixth computer program is executed, lead to the implementation of the additional step (iii.2) of the design method according to any one of claims 3 to 7.

18. Medium readable by a computer on which is recorded at least one computer program present in a set of computer programs according to any one of the two preceding claims.

19. Computer readable medium on which at least one of:

- a third computer file (13) generated by the design method according to any one of claims 1 to 14;

- a fourth computer file (14) generated by the design method according to claim 10;

- A fifth computer file generated by the design method according to any one of claims 1 1 or 12; - a sixth computer file generated by the design method according to any one of claims 13 or 14.

20. A prosthetic element (1) produced by the design method according to any one of claims 1 to 14.

21. Check key produced by the design method according to any one of claims 1 1 or 12.

22. Machining guides produced by the design method of any one of claims 13 or 14.