WO2022162095A1

WO2022162095A1 - Machinable preform for corono-radicular reconstruction, machinable element comprising such a preform, method for performing a corono-radicular reconstruction and method for manufacturing a preform

Info

Publication number: WO2022162095A1
Application number: PCT/EP2022/051954
Authority: WO
Inventors: Bruno Clunet-Coste; Bernard Maneuf; André Collombin
Original assignee: Clunet Coste Bruno; Bernard Maneuf; Collombin Andre
Priority date: 2021-01-27
Filing date: 2022-01-27
Publication date: 2022-08-04
Also published as: FR3119092A1; FR3119092B1

Abstract

The invention relates to a preform (1) for a dental prosthetic element, which comprises two opposing main faces (2, 3) and first fibres (7) parallel to a first direction (Y) and connecting the two opposing main faces (2, 3). Webs (20) of fibres are superimposed along the first direction (Y). The first fibres (7) include at least one reference fibre (8) formed in a different colour to the other first fibres. The preform has different mechanical properties at both ends in response to a load perpendicular to the first direction (Y).

Description

MACHINABLE PREFORM FOR CORONORADICULAR RECONSTRUCTION, MACHINABLE ELEMENT COMPRISING SUCH A PREFORM, METHOD FOR PRODUCING A CORONORADICULAR RECONSTRUCTION AND METHOD FOR MANUFACTURING A PREFORM

Technical area

The invention relates to a preform for the formation of a prosthetic element, a machinable element comprising such a preform, a method for manufacturing the preform and a method for producing a coronal-radicular reconstruction by means of the preform and coronal-radicular reconstruction.

Prior technique

In dentistry, it is conventional to use prosthetic elements to perform care and in particular to perform dental reconstructions. It is common to use an inlay-core, an implant pillar or a dental crown which are one-piece elements, that is to say which form a single piece. These prosthetic elements are made of a single material or a single set of materials. It is known to use metal alloys for the manufacture of prosthetic elements. Generally, the metal alloys used are stainless steels, titanium or equivalent materials such as mineral materials. It is still possible to produce prosthetic elements in monolithic ceramics and in particular in zirconia. Unfortunately, the materials presented above have a modulus of elasticity which is higher than that of dentin, which can lead to separation between the dentin and the prosthetic element or to a fracture of the dental root. Furthermore, the use of a prosthetic element in a hard, one-piece material makes it dangerous to disassemble the tooth when it is necessary to intervene by grinding the prosthetic element to access the apical canal zones. Such an intervention must be carried out when an infection breaks out. The prosthetic elements can be formed in different ways, for example by a lost-wax casting technique in a prosthesis laboratory or by machining a preform made from a metal alloy, a composite material or a ceramic. The prosthetic element can be obtained from the preform at the end of a computer-aided design operation (CFAO in French or CAD CAM in English for Computer-Aided Design and Computer-Aided Manufacturing).

Different configurations of prosthetic elements have been proposed and/or are used. The document FR2588181 proposes an endobuccal prosthesis made of composite material. This prosthesis is used for the formation of a post for abutments or an inlay for a dental reconstruction, for example for a coronal-radicular reconstruction. The post is formed by bundles of fibers assembled in a resin matrix. These tenons are conventionally made by pultrusion. With such a post, it is necessary to glue the abutment to the post, which creates an additional interface and therefore an increased risk of failure. The false stump fills the empty space left by the tooth to serve as a support for the crown. Such a structure replaces a one-piece core inlay by proposing a prosthetic element formed by two parts. Another fiber composite post is described in document EP0432001 which uses parallel and continuous fibers along the longitudinal axis of the post. However, these posts are manufactured on site with fibers placed by hand in the dental canal, which implies disparities between the achievements and immobilization of the patient during all the stages of production.

Document US 2002/086266 proposes producing a preform which will be machined by CAD/CAM in order to form a dental prosthetic element such as a crown, a post, an inlay or an onlay. The preform is formed by a fiber reinforced composite material. The fibers can be of any size and optionally woven. They can also be flocked. Document WO201 7/098096 describes the fabrication of an inlay core fabricated by CAD/CAM from a machinable disc. The inlay core is formed by unidirectional fibers embedded in a polymer matrix. Circular rods are made by pultrusion. The rods are made up of unidirectional fibers embedded in a polymer matrix. The rods are cut into sections and are positioned in circular cells of a support. The support is a standard CAD/CAM circular disc.

The document WO2010/109496 describes the use of a composite material which is formed by resistant fibers associated with a polymer matrix. The composite material is intended to form either a dental crown or a post. The mechanically strong fibers are woven or knitted together to form planar layers of reinforcement superimposed and bonded together. It appears that the layers linked together by crossing threads can slip. The planar layers are linked together by means of several transverse reinforcing elements. The transverse reinforcing elements can be interwoven with the planar reinforcing layers. The composite material is subjected to an etching step to form a prosthetic element.

Object of the invention

An object of the invention is to provide a method of manufacturing a prosthetic element which is easy to implement and which makes it possible to form a prosthetic element which provides better mechanical performance.

The method for manufacturing at least one machinable preform for a prosthetic element comprising the following steps:

- providing a three-dimensional mesh formed by a plurality of fibers and a plurality of attachment points, each fiber of the plurality of fibers having at least one attachment point with another fiber of the plurality of fibers so that the mesh retains its shape when it is subjected to a first stress value, the mesh defining a porous structure, the plurality of fibers comprising a plurality of first fibers arranged parallel to each other and oriented in a first direction,

- filling the mesh with a first resin, the first resin applying the first lattice constraint,

- polymerize the first resin.

The method is remarkable in that the lattice forms at least two distinct zones arranged successively along the first direction and has different mechanical properties in response to a first stress perpendicular to the first direction.

In one embodiment, the plurality of attachment points is formed by a weld between two fibers, a solder between two fibers, a knot between two fibers, an attachment between two fibers by means of a second resin in the polymerized state .

Preferably, the method comprises successively the installation of the plurality of first fibers on a support, the first fibers being parallel to each other and the production of the other fibers of the plurality of fibers to form the mesh.

Advantageously, the mesh is formed as a single piece by means of an additive manufacturing process or by a subtractive manufacturing process.

In another embodiment, the plurality of fibers includes a reference fiber having a color different from the first fibers and the first resin, the reference fiber being parallel to the first fibers.

In a preferred configuration, the lattice forms at least a central portion, an intermediate portion and a peripheral portion, the intermediate portion surrounding the central portion and separating the central portion and the peripheral portion, the volume content of first fibers in the central portion being greater than the volume content of first fibers in the intermediate portion, itself greater than the volume content of first fibers in the peripheral portion. It is also advantageous to provide, in the central portion, that the volume content of first fibers is greater than the total volume content of the other fibers of the plurality of fibers.

Advantageously, the first fibers extend continuously from a first face to an opposite second face, the first face and the second face being opposite in the first direction.

In another configuration, the first resin has a Young's modulus lower than the Young's modulus of the mesh in the first direction and in a direction perpendicular to the first direction.

Preferably, the method further comprises forming at least one mark on the at least one side face of the machinable preform at the interface between two distinct zones of the at least two distinct zones.

In an advantageous embodiment, the plurality of fibers comprises second fibers extending perpendicular to the first direction in the form of a plurality of layers of second fibers.

It is preferable to provide that each first fiber is attached to at least one layer of the plurality of layers by an attachment point of the plurality of attachment points.

In a particular configuration, the at least two distinct zones are three zones arranged consecutively in the first direction. The three zones are distinguished from each other by at least one of the following parameters: the volume percentage of second fibres,

- the distance between two layers of successive second fibers,

- the reinforcement of the layers of second fibers when the layers are woven,

- the chemical composition of the second fibers forming the layers of second fibers,

- the orientation of the warp and weft fibers when the sheets of second fibers are woven sheets. It is also advantageous to consider a method which comprises at least the following steps: providing an impression of a tooth to be repaired,

- calculate the dimensions of three zones arranged successively in the first direction and representative of a root anchorage, a pulp box and a coronal reconstruction,

- define the dimensions of the central portion perpendicular to the first direction, the dimensions of the central portion being chosen greater than the dimensions of the root anchoring zone perpendicular to the first direction

- define the dimensions of the layers of second fibers so as to extend beyond the dimensions of the root anchoring zone, the pulp box zone and the coronary reconstitution zone perpendicular to the first direction and define the configurations layers of fibers along the first direction to define the at least three zones,

- form the three-dimensional lattice.

Preferably, the method comprises the manufacture of a plurality of machinable preforms rigidly connected to one another in the form of a support, the preforms of the plurality of machinable preforms being mechanically connected to one another at least by the first polymerized resin.

Advantageously, the preforms of the plurality of machinable preforms are mechanically connected together by fibers of the plurality of fibers with the exception of the first fibers.

It is also advantageous to provide a step for singling out each of the preforms which can be machined by etching the support.

The invention also relates to a machinable preform facilitating the production of a prosthetic element and ensuring better mechanical behavior with respect to the dentin in comparison with the machinable preforms of the prior art. To this end, the machinable preform for a dental prosthetic element comprises a lattice three-dimensional embedded in a first resin in the polymerized state. The three-dimensional mesh is formed by a plurality of fibers and a plurality of attachment points, each fiber of the plurality of fibers having at least one attachment point with another fiber of the plurality of fibers. The plurality of fibers comprises a plurality of first fibers arranged parallel to each other and oriented in a first direction, the plurality of attachment points having an interface with the first resin. The first fibers continuously connect two opposite faces in the first direction. The lattice forms at least two distinct zones arranged successively along the first direction and having different mechanical properties in response to a first stress perpendicular to the first direction.

Advantageously, the lattice forms three zones arranged consecutively in the first direction.

The invention also relates to a method for manufacturing a dental prosthetic element which is easy to implement and which makes it possible to form a prosthetic element that is better adapted to the differences in mechanical strength required between root anchoring and coronal reconstruction.

There is a tendency to solve this problem by means of a method for manufacturing a dental prosthetic element comprising at least the following steps:

- provide a preform that can be machined according to the previous configurations,

- provide an impression of a tooth to be repaired,

- etching the machinable preform to reproduce the dimensions of the impression of the tooth to be repaired and to define at least one root anchoring, and a coronal reconstitution, starting respectively from a root anchoring zone and from a coronal reconstitution zone .

The subject of the invention is a process for producing a coronal-radicular restoration which is easy to implement and which forms a coronal-radicular restoration mechanically better adapted to the tooth wall. The process for producing a corono-radicular restoration comprises the following steps: - provide a prosthetic element according to the previous configuration,

- install the prosthetic element in a dental canal of a laboratory model.

Another subject of the invention is a corono-radicular restoration which is better adapted to the dental wall. We tend to solve this problem by means of a coronal-radicular restoration of a laboratory model, in which the prosthetic element comprises:

- a three-dimensional mesh embedded in a first resin in the polymerized state, the three-dimensional mesh being formed by a plurality of fibers and a plurality of attachment points, each fiber of the plurality of fibers comprising at least one attachment point with another fiber of the plurality of fibers, the plurality of fibers comprising a plurality of first fibers arranged parallel to each other and oriented in a first direction, the plurality of attachment points having an interface with the first resin.

The first fibers continuously connect two opposite faces of the prosthetic element from root anchorage to coronal reconstruction in the first direction. The mesh has different mechanical properties between the root zone and the prosthetic reconstitution zone arranged successively in a first direction. The different mechanical properties are in response to a first stress perpendicular to the first direction.

Brief description of the drawings

Other advantages and characteristics will emerge more clearly from the following description of particular embodiments and implementations of the invention given by way of non-limiting examples and represented in the appended drawings, in which:

- Figure 1 schematically shows a preform according to the invention

- Figure 2 schematically shows a form of prosthetic element to be machined in a preform according to the invention; - Figure 3 schematically shows a prosthetic element made from a preform according to the invention;

- Figure 4 illustrates, schematically, a coronal-root reconstruction using a prosthetic element according to the invention;

- Figure 5 illustrates, schematically, another embodiment of a preform according to the invention;

- Figure 6 illustrates, schematically, yet another embodiment of a preform according to the invention;

- Figure 7 illustrates, schematically, a machinable element grouping together a plurality of preforms according to the invention;

- Figure 8 illustrates, schematically, a machinable element grouping together a plurality of preforms according to the invention, the constituent elements of which have been partially pooled.

Description of embodiments

FIG. 1 represents a preform 1 which is a machinable preform intended to cooperate with a computer-aided manufacturing machining device to form a dental prosthetic element and preferably a prosthetic element for a dental restoration. The preform 1 is a three-dimensional element which has a first main face 2, a second main face 3 and at least one side face 4 which connects the first and second opposite main faces 2 and 3. The preform 1 is intended to be machined in such a way to define a prosthetic element which will be used in a dental restoration, for example a dental restoration of a laboratory model.

The preform 1 is a composite block which comprises a first resin 5 which is associated with fibers. The machinable preform 1 comprises a three-dimensional mesh embedded in a first resin 5 in the polymerized state. The three-dimensional mesh is formed by a plurality of fibers and by a plurality of attachment points 6 between the fibers. A point of attachment 6 is a point of attachment between at least two fibers having different orientations so that the at least two fibers are mounted fixed with respect to each other. Each fiber of the plurality of fibers has at least one attachment point 6 with another fiber of the plurality of fibers. The first resin 5 has a Young's modulus lower than the Young's modulus of the mesh in the first direction Y and in a direction perpendicular to the first direction Y.

The plurality of fibers comprises a plurality of first fibers 7 which are arranged parallel to each other and oriented along a first direction Y. The plurality of attachment points 6 has an interface with the first resin 5. The plurality of attachment points 6 ensures the mechanical strength of the lattice in addition to the first resin 5. The first fibers 7 continuously connect the two opposite faces 2,3 of the machinable preform 1 along the first direction Y. The lattice forms at least two distinct zones arranged successively along the first direction Y. The two distinct zones have different mechanical properties in response to a first stress perpendicular to the first direction Y. After addition of the first resin 5, the machinable preform 1 comprises at least two distinct zones preferably three or at least three distinct zones 8, 9 and 10 arranged successively in the first direction Y.

The machinable preform 1 is formed by several sets of fibers which are oriented in different directions. The orientation of a fiber is defined by its longitudinal axis, the axis of its longest dimension. The machinable preform 1 is anisotropic. It has different mechanical characteristics, for example a Young's modulus, in the first direction Y and in a direction perpendicular to the first direction Y. The machinable preform 1 also has different mechanical characteristics, for example a Young's modulus, at each of its ends in the first direction Y when a stress is exerted in a direction perpendicular to the first direction Y.

In a particular embodiment, the first fibers 7 can be twisted fibers. In a preferred embodiment, the first fibers 7 have a maximum diameter of less than 0.45 mm and are advantageously unidirectional fibers. The first fibers 7 used can be glass fibers and for example E, R, S, AR and XRO fibers. It is also possible to use silica fibers. Ceramic fibers, boron fibers, silicon carbide, carbon fibers can also be used. Generally, the fibers can be inorganic, organic and/or natural and/or metallic. It is also possible to use hybrid fibers, for example Zr-Ti fibers. The first fibers 7 can be formed by fibers made of ethylene, polyetheretherketone (PEEK) or polyamide. Generally, the first fibers 7 are biocompatible fibers. They may also be fibers obtained by an additive manufacturing process, for example metal-ceramic or metal-zirconia hybrid fibers, in particular titanium-zirconium or metal-ceramic material fibers.

The machinable preform 1 does not have the same mechanical properties at its two ends, which makes it possible to better adapt the machinable preform 1 to the differences in stresses which exist in the dental canal and in the coronal part. The machinable preform 1 is inhomogeneous along the first direction Y and it has an end intended to form a coronal portion and an end intended to form a root anchorage.

In order to further adapt the machinable preform to the needs of a dental prosthetic element, for example a coronal-radicular reconstruction, the machinable preform 1 comprises three or at least three zones 8, 9 and 10 mounted successively along the first direction Y. The different zones are distinguished from each other by different mechanical characteristics in response to a stress perpendicular to the first direction Y. Preferably, the mechanical differences correspond to deviations of at least 10% to distinguish a chosen mechanical difference and a manufacturing hazard.

The three zones 8, 9 and 10 of the preform 1 are intended to form respectively, after machining, a prosthetic element 14 which has a root anchor 11, a pulp box 12 and a coronal reconstruction 13 as shown in Figure 4. The pulp box 12 separates the coronary reconstruction 13 and the root anchorage 11. Advantageously, the pulp box 12 has a section greater than the section of the root anchorage 11 and lower than the section of the coronary reconstruction 13. The root anchor 11 , the pulp box 12 and the coronary reconstruction 13 have different dimensions perpendicular to the Y direction as well as different mechanical properties.

The preform 1 has a root anchorage zone 8 which will be machined to form the root anchorage 11, a pulp box zone 9 which will be machined to form the pulp box 12 and a coronal reconstruction zone 10 which will be machined to form the coronal reconstruction 13. The root anchor 11 is intended to ensure the mechanical connection between the prosthetic element 14 and the dentinal wall 15 inside the dental canal 16 of the dental root 17.

To facilitate the use of the machinable preform 1 and in particular its etching to form a prosthetic element 14, it is advantageous to mark one end of the machinable preform 1, for example the end intended to form the root anchoring zone 8. In least one mark 18 is preferably made in a zone of the preform 1 which is intended to be etched, that is to say a sacrificial zone during the etching step to form the prosthetic element 14. It is advantageous that the reference(s) 18 indicate the interface between two zones 8 to 10 having different mechanical performance.

In order to functionalize the different zones 8 to 10 of the machinable preform 1 to adapt to the specific needs which exist and which are different from one end to the other of the prosthetic element 14, the fibers which form the lattice are arranged in different ways. The fiber organization at one end is different from the organization at the other end and it is even possible to define more areas with different fiber organizations to obtain different mechanical characteristics. The different zones 8 to 10 are mechanically connected at least by means of the first fibers 7 to ensure good transfer of forces in the first direction Y.

To form a machinable preform 1 whose mechanical characteristics differ between the two ends while being well controlled, it is advantageous to provide a mesh formed from the plurality of fibers. The three-dimensional mesh is formed by a plurality of fibers and by a plurality of attachment points 6. Each fiber of the plurality of fibers has at least one attachment point 6 with another fiber of the plurality of fibers so that the mesh retains its shape when subjected to a first stress value. The lattice defines a porous structure. The fibers of the mesh are attached to each other with at least one attachment point 6 per fiber and preferably several attachment points 6 per fiber. It is advantageous for the first fibers 7 or at least part of the first fibers 7 to have several attachment points 6 with other fibers. By means of the plurality of attachment points 6, the lattice forms a rigid structure for the subsequent steps of the manufacturing process of the preform 14.

Conventionally, when a preform 1 is made with a set of fibers forming, for example, a woven or knitted material, the introduction of the resin results in a deformation of the stack of the different layers of fibers of the preform 14. layers 20 of fibers are deformed, the fibers move inside the layers 20 which voluntarily have a certain laxity to allow the passage of the resin. Consequently, the structures initially formed to support mechanical characteristics become deformed and no longer meet the initial need.

In order to overcome this drawback, the lattice is configured to retain its shape when subjected to a first set of stresses. The first set of constraints corresponds to the set of constraints applied during the filling of the porous structure formed by the lattice by means of a first resin 5. Thus, during the filling of the lattice with the first resin 5 which applies the first constraint to the lattice , the trellis retains its shape and maintains the technical characteristics that were initially defined.

The first resin 5 is introduced into the mesh so that the first resin 5 completely fills the pores of the mesh. The first resin 5 is subsequently polymerized. A machinable preform 1 is obtained with a mesh embedded in the first polymerized resin 5. The preform 1 is anisotropic in its characteristics between a stress along the first direction Y and a stress perpendicular to the first direction Y and there is a difference in mechanical performance for a stress perpendicular to the first direction Y between the two opposite ends of the preform .

The attachment points 6 between the fibers can be formed by any suitable means, for example by welding, by brazing, by a knot between fibers, by a second resin. It is possibly possible to use a prior fixing of the fibers by fixing points 6 in the material forming the first resin 5. This material is polymerized before embedding the mesh in a subsequent step. It is also possible to use a resin which is different from the first resin 5 and which advantageously has a Young's modulus higher than that of the first resin 5. The first resin 5 and the second resin are advantageously resins of the same family. to facilitate the mechanical connection between the matrix in first resin 5 and the attachment points 6 in second resin. The first resin 5 and the second resin can be differentiated by their filler content which modifies the mechanical properties.

The first resin 5 can be a single resin or a mixture of resins. The first resin 5 mechanically binds the fibers together, in addition to the attachment points. The first resin 5 can be a thermosetting resin or a thermoplastic resin. The first resin 5 can be a hybrid composite resin or a nanohybrid composite resin. Hybrid and nano-hybrid composite resins have fillers that are less than 10 microns or less than 5 microns or less than 3 microns or less than 1 micron. The first resin 5 can be an organic, mineral, vegetable or organic resin. The first resin 5 forms the matrix of the preform 1 . The matrix can be doped with particles of micrometric and/or nanometric size in order to modify its mechanical performance, its color, its crosslinking and/or other physico-chemical properties. The matrix can also be doped with short fibers or whiskers/wiskers. For the first resin 5, it is possible to use one or more thermosetting resins chosen from PMMA, TEGDMA, BISGMA, BDMA, HDDMA, UDMA, epoxy resins and polyester resins, for example vinylester. It is also possible to use thermoplastic resins chosen from PC, PGM and PU.

In a particular configuration, the preform 1 is full. It is also advantageous to provide that the preform 1 is formed solely by the fibers and the resin matrix.

The plurality of fibers includes the first fibers 7 and other fibers to form the mesh. The plurality of fibers may include second fibers 19 which extend at least along a direction perpendicular to the first direction Y to form the mesh. In a particular embodiment, the second fibers 19 are linked together in order to define several layers 20 of second fibers 19. The layers 20 of second fibers 19 define planes perpendicular to the first direction Y. Alternatively, it is possible to provide sheets 20 of second fibers 19 which are not planes perpendicular to the first direction Y. The fibers 19 forming a sheet 20 are preferably fixed together by fixing points 6. The sheet may or may not be a woven material - woven or knitted. In an alternative embodiment, the mesh has no ply 20. Preferably, each first fiber 7 is fixed to at least one ply 20 of the plurality of plies 20 by a fixing point 6 of the plurality of fixing points 6.

It is particularly advantageous to install the first fibers 7 parallel to each other on a support and then to fix the sheets 20 on the first fibers 7. The pre-assembled sheet 20 is fixed on the first fibers 7. The monolithic sheet 20 is fixed to the first fibers 7 by the attachment points 6. In an alternative embodiment, the sheet 20 can be a monolithic element obtained by an additive method, of the three-dimensional printer type or subtractive by etching a substrate. In another alternative embodiment, the sheet 20 is woven, knitted or a non-woven structure. The preform 14 may also have plies 20 of fabric and plies

20 monoliths. Different types of attachment points 6 can be used between the layers 20 and within a layer 20.

When the second fibers 19 are strictly perpendicular to the first direction Y, the plurality of fibers can also comprise third fibers

21 which have any orientation and which serve to fix the fibers together to form the mesh.

In a particular embodiment, the mesh is a monolithic element exclusively formed by an additive method, also known as 3D printing, or formed by a subtractive method by etching a substrate to define the different orientations of the fibers.

In another embodiment, the first fibers 7 are arranged on a support parallel to each other. The other fibers are installed to define the mesh. The fibers are put in place in a three-dimensional way, for example from the arms of one or more robots, and the physical connection between the fibers is made permanent by means of the attachment points 6. For example, the fibers are pre-impregnated and the polymerization is carried out at the junction of the fibers to form an attachment point 6. The polymerization can be obtained by a thermal or electromagnetic stimulus. It is also possible to make a spot weld or solder at the fiber junction. The support makes it possible to fix the first fibers relative to each other during the step of forming the preform. After formation of the preform, the support can be removed without deforming the preform. The connections between the fibers make it possible to ensure that the shape of the mesh is maintained during the addition of the resin to form the preform regardless of the presence or absence of the support.

In this way, step by step, the mesh of fibers is mounted in three dimensions around the first fibers 7. This technique can be combined with the use of one or more layers 20 in order to fix the position of the layers 20 according to the first direction Y. By installing the fibers differently between the bottom of the lattice and the top of the lattice, it is possible to differentiate the characteristics of the preform 1 over the height of the preform 1, that is to say along the first direction Y.

The use of a method which successively comprises the installation of the plurality of first fibers 7 on a support then the production of the other fibers of the plurality of fibers to form the trellis is particularly advantageous because such a method is simple to implement. work and it is economical.

The lattice structure has a first Young's modulus in the first Y direction, a second Young's modulus in a second direction perpendicular to the first Y direction and a third Young's modulus in a third direction perpendicular to the first direction and to the second direction. The first fibers 7 and the second fibers 19 are selected and arranged preferentially so that the first Young's modulus is different from the second and third Young's moduli and preferentially to be greater than the second and third Young's moduli. Advantageously, the first Young's modulus has a value of less than 35 GPa so as not to put too much stress on the dentin or any other organ inside which the preform is intended to be inserted, for example during the chewing phases.

The preform 1 preferably has different mechanical performance depending on whether the machinable preform 1 is stressed at its center or at its periphery in the first direction Y. In a section plane perpendicular to the first direction Y, it is possible to divide the machinable preform 1 in a central portion 22 and a peripheral portion 24 or in a central portion 22, an intermediate portion 23 and a peripheral portion 24. The central portion 22 is inscribed inside the intermediate portion 23, itself inscribed on the inside the peripheral portion 24. The intermediate portion 23 defines a ring separating the central portion 22 and the peripheral portion 24. The intermediate portion 23 can have any internal shape and any external shape, but preferably circular shapes. The central portion 22, the intermediate portion 23 and the peripheral portion 24 extend from the first main face 2 to the second main face 3. The central portion 22, the intermediate portion 23 and the peripheral portion 24 are distinguished from each other by different mechanical characteristics vis-à-vis the mechanical stresses in the first direction Y. It is possible to differentiate the central portion 22, the intermediate portion 23 and the peripheral portion 24 by different contents of first fibers 7. The content of first fibers 7 is preferentially decreasing from the central portion 22 to the peripheral portion 24. The peripheral portion 24 can optionally be devoid of first fiber 5.

The plurality of fibers includes fibers which mechanically connect the central portion 22, the intermediate portion 23 and the peripheral portion 24, preferably second fibers 19.

In a preferred embodiment, in the central portion 22, the fibers are mostly first fibers 7 and advantageously unidirectional fibers. In the central portion 22, the volume content of first fibers 7 is greater than the total volume content of the other fibers of the plurality of fibers. The central portion 22 mainly acts on the mechanical characteristics along the first direction Y. The first fibers 7 advantageously represent at least 50% of the volume of the central portion 22 and more preferably at least 80% of the volume of the central portion 22. In the central portion 22, the content by volume of resin or of resin and fillers is at least equal to 10%, preferably at least equal to 20% and less than 50%. Advantageously, the central portion 22 has an oval, circular or substantially circular section along the section plane perpendicular to the first direction Y.

Preferably, the central portion 22 extends over a distance at least equal to 1 mm in all directions perpendicular to the first direction Y. It is also advantageous to provide that the central portion 22 extends over a distance at most equal to 4mm in all directions perpendicular to the first direction Y. By way of example, the central portion 22 contains or has a circular section whose diameter is between 1 mm and 4 mm, preferably between 1 mm and 2 mm.

In order to facilitate the machining of the preform 1, it is particularly advantageous to be able to identify a specific axis of the preform 1 which represents the first direction Y. The specific axis is advantageously formed by a reference fiber 25 oriented along the first direction Y or possibly offset by a known value with respect to the first direction Y. The reference fiber 25 is advantageously a different fiber from the first fibers 7. The reference fiber 25 is advantageously a colored fiber whose color is different from the other fibers and of the matrix at least in the central portion 22. Thus, by observing the two opposite faces of the preform 1, the user is able to identify the reference fiber 25 and therefore to identify the first direction Y between the two opposite main faces 2 and 3. The reference fiber 25 can be fixed only to the first fibers 7 or it can be fixed to other fibers. It is advantageous to place the reference fiber 25 in the center of the central portion 22. This makes it possible to identify the position of the central portion 22 in the machinable preform 1. It is then easier to machine the machinable preform 1 to form the prosthetic element and to have the maximum of the first fibers 7 which extend over the entire height of the prosthetic element to ensure good transfer of forces between the root anchorage 11 and the coronal reconstruction 13.

It is also advantageous to provide that, in the intermediate portion 23, the fibers connecting the two opposite faces 2 and 3 are mainly or exclusively first fibers 7 and more preferably unidirectional fibers. The first fibers 7 advantageously represent less than 80% of the volume of the intermediate portion 23, preferably between 50% and 80% of the volume of the intermediate portion 23. The volume content of resin or of resin and dopants is at least equal to 10% preferably at least equal to 20% and less than 50%.

When the intermediate portion 23 has a circular section, it is advantageous to place the reference fiber 25 in the center of the intermediate portion 23. Thus, the user is able to identify the first direction Y and the center of the intermediate portion 23. The user can then machine the preform 1 without taking into account the planes defined by the two main faces 2 and 3, the lateral face 4 and possibly any hazards when defining the preform 1, for example when the two main faces 2 and 3 are not parallel and/or are damaged. The use of the reference fiber 25 in association with a marker 18 on the outer face of the preform to delimit at least one of the zones 8 to 10 along the Y direction allows a user to know the distribution of the fibers and therefore the orientation of the preform 1 and the position of the central portion 22. It is easier to machine the preform 1 according to the shape of the impression to be reproduced and to place the mechanical characteristics of the central portion 22 in a part of the l prosthetic element 14 which extends over the entire height of the impression from the root anchor 11 to the coronal reconstruction 13.

It is particularly advantageous for the fiber content in the intermediate portion 23 to be lower than the fiber content in the central portion 22. It is also advantageous for the fiber content in the peripheral portion 24 to be lower than the fiber content in the intermediate portion 23. The fiber content is calculated by dividing the volume occupied by the fibers by the total volume of the central portion 22, of the intermediate portion 23 or of the peripheral portion 24 over the height of the preform 1 .

Advantageously, the reference fiber 25 is made of a material which is more easily etched compared to the materials forming the matrix and compared to the materials forming the first fibers 7, the second fibers 19 and the third fibers 21. It is then easier to operate on an infected apex by etching the reference fiber 25 with a reamer or any other equivalent device.

Advantageously, the percentage by volume of first fibers 7 in the peripheral portion 24 is less than the percentage by volume of first fibers 7 in the central portion 22 and in the intermediate portion 23 by at least 20% by volume. In a particular embodiment, the volume proportion of second fibers 19 is greater than the volume proportion of first fibers in the peripheral portion 24 as illustrated in FIG. 6 and what can be obtained in the embodiment of FIG. 5. In a preferred configuration, in the peripheral portion 24, the volume percentage of first fibers 7 decreases away from the center of the central portion 22. The decrease in the volume percentage can be linear with the distance from the center or the decrease can apply another rule. It is also possible to provide a volume percentage of first fibers 7 which is constant in the intermediate portion 23 or substantially constant in the intermediate portion 23 away from the center of the central portion 22. It can be the same in the portion device 24.

Preferably, in the peripheral portion 24, the volume content of first fibers 7 is at least equal to 10% and preferably less than 50%. In the peripheral portion 24, the first fibers 7 are advantageously unidirectional fibers and they preferably represent between 10% and 50% of the volume of the peripheral portion 24.

As illustrated in Figures 1, 2, 5 and 6, in order to form a machinable preform 1 which is particularly well suited to the production of a dental prosthetic element, it is particularly advantageous to provide that the preform 1 has at least three consecutive zones 8 to 10 having different mechanical properties along the first direction Y as well as for at least the coronal reconstruction zone 10 and optionally for the pulp box zone 9 at least three portions 22 to 24 having different mechanical properties along a direction perpendicular to the Y direction.

It is advantageous to have a root anchorage 11 which is formed or mainly formed or exclusively by the central portion 22. Preferably the volume of the root anchorage is mainly formed by a bundle of first fibers 7. It is particularly advantageous to provide that the root anchor 11 is devoid of the peripheral portion 24 and optionally devoid of the intermediate portion 23, that is to say formed solely by the central portion 22 or part of the central portion 22. In the root anchor 11, the other fibers and preferably the second fibers 19 are arranged so that the root anchor 11 has identical mechanical performance in the different directions perpendicular to the first direction Y or substantially identical. For example, the root anchor 11 has identical or substantially identical mechanical characteristics radially from the reference fiber 25 in all the directions perpendicular to the first direction.

The first fibers 7 of the root anchor 11 are arranged so as to withstand tensile stresses in the first direction Y. Preferably, the volume proportion of first fibers 7 and of other fibers is constant over the height of the root anchor 11 It is advantageous to form the root anchoring zone with layers 20 which have different orientations at least in the central portion 22 to homogenize the comprising of the root anchoring 11 radially of a first fiber 7 and of the fiber of reference 25.

In the root anchoring zone 8 of the preform 1 and therefore in the root anchoring 11, the first fibers 7 are mostly unidirectional fibers oriented in a first direction Y in order to better withstand the tensile stresses. It is therefore particularly advantageous to provide that the first direction Y will be the longitudinal direction of the prosthetic element 14 or substantially the longitudinal direction of the prosthetic element 14 so that the first fibers 7 are oriented in the longitudinal direction, for example a tenon or an inlay core. The first direction Y corresponds to the main direction of insertion of the prosthetic element 14.

The pulp box 12 makes it possible to embed the coronal-radicular reconstruction A in the pulp chamber 17. It has been observed that the pulp box 12 is subjected to a significant set of stresses in the form of peripheral tensile stresses perpendicular to the first direction Y. The peripheral tensile stresses are at the origin of an accentuated deformation and a delamination of the pulp box 12. It is therefore interesting to form a pulp box 12 having different mechanical performances from the anchoring root canal 11 to reduce the likelihood of delamination and thus avoid secondary fractures of the residual dental tissue and decohesion of the prosthetic elements.

In the pulp box zone 9 intended to form the pulp box 12, the volume percentage of other fibers is greater than the volume percentage of first fibers 7. The first fibers 7 provide mechanical cohesion over the height of the pulp box 12. This configuration allows to improve the resistance of this part of the preform 1 to peripheral tensile stresses perpendicular to the first direction Y. The pulp box 12 has a central portion 22 and at least part of the intermediate portion 23 or even all of the intermediate portion 23 and part of the peripheral portion.

A proportion of other fibers greater than the proportion of first fibers 7 is advantageously present in the peripheral portion 24, preferably in the intermediate portion 23.

It is particularly advantageous to use a zone of the pulp box 9 whose volume of fibers contains up to 80% other fibers and 20% first fibers 7.

The coronal reconstruction 13 is subjected, in the zone of contact with the outer rim of the root 17, to multidirectional tensile stresses and must in particular withstand the strongest peripheral stresses. In the coronary reconstruction zone 10 intended to form the coronary reconstruction 13, the volume percentage of other fibers, for example of second fibers 19, is greater than the volume percentage of first fibers 7. The coronary reconstruction 13 comprises the central portion 22, the intermediate portion 23 and part of the peripheral portion 24.

It is advantageous for the central portion 22 to be configured to adapt to the mechanical constraints of the root anchorage 11, for the intermediate portion 23 to be adapted to the mechanical constraints of the pulp box 12 and for the peripheral portion 24 to be adapted to the mechanical constraints of coronary reconstruction 13. The ratio of the volume percentages between fibers connecting the two opposite faces 2 and 3 and the other fibers, for example the second fibers, is different between the coronary reconstruction 13, the pulp box 12 and the root anchor 11 in order to provide different mechanical properties. and adapt the performance of the preform to the constraints to be supported.

Preferably, the central portion 22 is formed mainly, by volume, of first fibers 7 extending along the first direction Y. The central portion 22 preferably comprises between 75% and 85% by volume of fibers and between 15% and 25% volume of resin. Preferably, the central portion 22 comprises 80% by volume of fibers and 20% by volume of resin.

It is also advantageous to provide that the proportion by volume of layers 20 in the intermediate portion 23 and of the peripheral portion 24 is preferentially greater than the proportion by volume in the central portion 22, preferentially greater by at least 10% by volume, even more preferentially at least 30% by volume, or even equal to 50%, but preferably not more than 70% by volume.

It is possible to provide uniform sheets 20 from one end to the other of the preform 1, for example woven, braided or knitted sheets 20. The differentiation of the mechanical characteristics for the three successive zones of the first direction Y is carried out by modifying the materials used, the orientation of the plies 20 with respect to each other, the reinforcement of the plies 20 and/or the distance between the layers 20. It is also possible to differentiate the mechanical performance between the intermediate portion 23 and the peripheral portion 24 by means of the third fibers 21. The fibers in the layer 20 can be bonded together in the form of a fabric, a knit or a braid. The layers 20 are superimposed along the first direction Y.

Alternatively, the sheets 20 are not uniform and they have differences between their central part and their peripheral part, for example the central portion of the sheet 20 corresponding to the central portion 22 is identical for all the layers 20 in order to impose the position of the first fibers 7. The central portion 22 forms openings of a first size. Around the central portion 22, the organization of the fibers differs between the root anchorage 11 and the coronary reconstitution 13 and preferentially between the root anchorage 11, the pulp box 12 and the coronary reconstitution 13. The differentiation in the size of the openings outside the central portion 22 between two consecutive layers 20 makes it possible to modify the mechanical performance between the root anchoring 11, the pulp box 12 and the coronal reconstruction 13.

As indicated above, the preform 1 defines at least three zones having different and successive mechanical performances along the first direction Y. The differentiation of the mechanical performances can be obtained by differentiating the characteristics of the plies 20. The differentiation of the mechanical characteristics can be obtained by differentiating at least one of the following parameters:

- the distance between two successive layers 20 in the first direction Y,

- the volume proportion in layers 20 at least in the central portion 22,

- the volume proportion in layers 20 at least in the intermediate portion 23,

- the volume proportion in layers 20 at least in the peripheral portion 24,

- the intrinsic mechanical performance of the layers 20,

- the orientation of the layers 20 relative to each other relative to a reference direction perpendicular to the first direction Y,

- the mechanical connections or the welds installed between the fibers 19 and the first fibers 7.

The different layers 20 defining the zones of the preform 1 can be identical or different. It is particularly advantageous to use different sheets 20, that is to say having different mechanical performances in order to be able to more easily differentiate the mechanical performances of the preform 1 according to directions perpendicular to the first direction Y.

The different plies 20 are separated by a resin zone 5. The separation distance between the plies 20 can be different between two plies 20 successive. By different distances is meant at least two different distances with a value of at least 10%, preferably at least 20%. The difference in distance is a manufacturing choice and not a production hazard. Preferably, two consecutive plies 20 along the first direction Y are separated by a layer of resin 5 whose thickness is advantageously at least equal to the thickness of the plies 20.

To define the different areas of the preform 1, the plies 20 can be divided into groups of plies 20 having different mechanical performance. The differences in mechanical performance may come from a different weft between the groups of layers 20 and/or by the use of different materials and/or by a different distribution of the fibers in the layers 20 in each group.

In another embodiment of the preform not shown, the preform 1 has a cross-section that increases from one end to the other, preferably continuously increasing. Advantageously, the evolution of the section of the preform 1 takes place in stages. Each level corresponds to a zone along the first direction Y having predefined characteristics to easily delimit each zone. The narrowest section corresponds to the root anchorage zone. The root anchoring zone 8 may comprise only the central portion 22. The central portion 22 extends from one end to the other of the preform 1 in the first direction Y. The intermediate portion 23 may extend from one end to the other of the preform 1 in the first direction Y. one end of the preform to the other in the first direction Y. The intermediate portion 23 is preferably present in the pulp box zone 9 and the coronal reconstruction zone 10. This embodiment is more complicated to produce or corresponds to a preliminary machining step to show the arrangements of the different zones in the preform 1 .

In a particular embodiment illustrated in FIG. 5, a central portion 22 is separated from the intermediate portion 23 by a first sheath 26 formed by one or more fibers which continuously go around the central portion 22, for example a web 20 Sheath can be restricted to one of multiple zones 8 to 10 along the first direction Y. It is advantageous for the first sheath 26 to extend over the entire height of the preform 1 .

A second sheath 27 can be used to separate the intermediate portion 23 and the peripheral portion 24. The second sheath 27 advantageously extends over the entire height of one of the zones 8 to 10, preferably the pulp box zone 9 and/or the coronal reconstruction zone 10. It is advantageous for the second sheath 27 to be absent from the root anchoring zone 8. It is also possible to provide a third sheath 28 which is located at the periphery of the peripheral portion 24.

In a particular embodiment, several additional sheaths are arranged in the intermediate portion 23 and/or in the peripheral portion 24 to form the trellis.

Each sheath is separated from the adjacent sheath by first fibers 7 and by first resin 5. The sheaths advantageously have a circular or substantially circular section along a cutting plane perpendicular to the first direction Y. The sheaths can be woven or knitted . Depending on the desired configurations, the same preform may comprise only woven sheaths, only knitted sheaths or a mixture of woven sheaths and knitted sheaths.

The first fibers 7 arranged between the sheaths are advantageously in the form of a crown. In other words, it is advantageous to evenly distribute the fibers between the two sheaths. The fibers can be arranged in the form of single fibers separated from each other by resin or in the form of an assembly of fibers, for example fiber-resin rods. The fibers can have a diameter of between 1 mm and 0.5 mm.

Between two consecutive sheaths, the volume percentage of fibers is advantageously less than 80% and preferably greater than 30%. The resin forming the preform can be deposited by injection, infiltration, infusion or any other method making it possible to obtain a laminate preferably free of bubbles and lack of resin.

In another embodiment of the preform which is illustrated in FIG. 6, the central portion 22 extends from one end of the preform to the other in the first direction Y. Several different layers of fibers 19, 21. The multiple layers of different fibers differ from each other in their mechanical performance. They also differ in their winding in order to be able to define an intermediate portion 23 and a peripheral portion 24. They are further distinguished in their extent along the first direction Y in order to be able to distinguish the root anchorage 11, the pulp box 12 and the reconstitution coronary 12. In the illustrated embodiment, there is at least one fiber 19,21 which extends in a form which resembles a spiral to connect several first fibers 7 and form at least part of the mesh.

It is particularly advantageous, during the winding step, to install one or more fibers extending along the first direction Y. The fibers can be unpolymerized or partially polymerized preimpregnated fibers.

The fibers are preferably unidirectional fibers, ribbons, simple woven sheaths, simple knitted sheaths. It is also possible to use hybrid sheaths with a core formed by a unidirectional fiber.

The first resin 5 of the preform 1 is polymerized before the machining step.

In addition to the reference fiber 25, the preform 1 advantageously has one or more markers 18 which are arranged on the at least one side wall 4. The marker(s) 18 are arranged so as to identify the separation between the different zones 8 to 10 arranged successively in the first direction Y.

The preform 1 is made by initially forming the lattice structure from the first and second fibers 7 and 19 then the first resin 5 is introduced to fill the holes. The preform 1 is intended to be machined in order to form a prosthetic element 14.

If necessary, the preform 1 is engraved so as to define the height of the prosthetic element 14, that is to say the dimension along the first direction Y. The preform 1 is engraved so as to define the dimensions of the prosthetic element perpendicular to the first direction Y and advantageously along the first direction Y. The preform is etched from an imprint representing the prosthetic element 14 to be formed.

The preform 1 advantageously has a height greater than the height of the cavity. It is then advantageous to engrave a greater or lesser height of the root anchorage 11 compared to the etching of the coronary zone 13 in order to facilitate the adaptation of the shape of the prosthetic element 14 to that of the footprint.

In a particular embodiment, the preform 1 is formed from the impression of the tooth to be repaired. The tooth is identified and the impression is taken so as to estimate the dimensions and the stress sets to be supported in each of the parts of the prosthetic element 14 intended to replace the tooth. The mesh is manufactured in such a way as to respond to its multiple sets of constraints which are distributed over the height of the prosthetic element 14 as well as between its central portion 22 and its peripheral portion 24. Once the mesh has been manufactured, the first resin 5 is added to a mold to form the machinable preform. The preform is then machined according to the impression of the tooth to be repaired so that the external shape of the preform adapts to that of the impression. The preform 1 can have any shape. The preform 1 can have a circular, square or rectangular section.

In another embodiment of a dental prosthetic element 14, the preform 1 is produced in a standardized manner. The shape of the preform 1 is chosen so as to be compatible with the machining equipment. The dimensions of the root anchoring zone 8, the dimensions of the pulp box zone 9 and the dimensions of the coronal reconstruction zone 10 are defined independently of the associated impression and of the prosthetic element 14 to be produced on the basis of information generically representing the teeth to be repaired. Lattices are made to represent standard tooth configurations. The preforms can distinguish the type of tooth, for example, a molar, a pre-molar and a canine which induces differences in mechanical characteristics in the lattices.

It is advantageous to provide different preform models which differ from each other by differences in the dimensions of the coronal part perpendicular to the first direction Y. It is also advantageous to provide different preform models 1 which differ from each other from the others by differences in the dimensions of the root portion 8 perpendicular to the first direction Y. By modulating the dimensions of the root anchoring 8 and coronal reconstruction 10 zones, it is possible to best adapt the characteristics of the preform 1 to those of the reconstitution. The dimensions of the lattices perpendicular to the first direction Y are adapted accordingly.

The preform 1 is machined in order to define the shape of the root anchor 11 and define the shape of the coronary reconstruction 13. This machining makes it possible to define the dimensions of the prosthetic element 14 in order to allow its insertion with the impression of a laboratory model.

The impression is taken, preferably by optical and computer means, for example with an impression camera, in order to determine the shape of the prosthetic element 14 to be produced. Once the impression has been taken, the lateral dimensions of the prosthetic element 14 are calculated and the preform 1 can be machined. The lateral dimensions of the prosthetic element 14 can be calculated using a computer, for example with instructions stored in a memory.

The mechanical characteristics of the preform 1 being different along the first direction Y and perpendicular to the first direction Y, the positions of the central portion 22, of the root anchoring zone 8, of the box zone pulpal 9 and the coronal reconstruction zone 10 are determined in the preform 1 before carrying out the machining independently of the distance separating the two opposite faces 2 and 3 and of the orientation of these two faces.

An impression of a tooth to be repaired is initially provided. This impression is scanned in a laboratory scanner. Alternatively, a footprint computed from data from a computer-aided design system is provided. Then, based on the data representative of the impression, a step is performed to calculate the dimensions of a root anchor 11 , a pulp box 12 and a coronal reconstruction 13 in three dimensions. Preferably, a digitized three-dimensional image of the future reconstruction is provided.

In a particular embodiment, the root anchoring zone 8, the pulp box zone 9 and the coronary reconstitution zone 11 are aligned consecutively along the first direction Y on the preform 1. The three zones are aligned so as to make coincide with predefined marks on the digitized image in the three dimensions of the preform 1 .

The alignment of the three zones can be carried out by aligning the axes of the preform 1 with the axes of the representative image of the future reconstitution. Thereafter, it is advantageous to align a reference zone of the image representative of the reconstitution, for example the pulp box zone 9, to make it coincide with the equivalent zone from the reference mark(s) 18 of the preform machinable.

In a preferred embodiment, the position of the central portion 22 of the root part 11 inside the root anchorage zone 8 is calculated first. Once the central portion 22 of the root part 11 has been placed in the preform, the positions of the other parts of the reconstitution are calculated.

During the production of the preform 1, in a calculation step, a computer advantageously defines and aligns one or more markers which will be used by the machining equipment to produce the root anchorage 11 in the area root anchorage 8, as well as the shape of the pulp box 12 and of the coronary reconstruction 13 in their respective areas of the preform 1.

A step of taking an impression has been carried out and the information collected and/or calculated is used to carry out the machining of the preform 1. From the impression, the specialist defines the orientation of the first direction Y as well as the height of the different zones.

The marker 18 of the preform 1 is preferentially used to determine the position and extent of the pulp box zone 9. By means of the marker 18 and the reference fiber 25 of the preform 1, it is possible to define the position of the three-dimensional image of the reconstruction in the preform independently of the orientation of the external faces of the preform which will be machined. A set of machining data is supplied to the machining equipment to etch the prosthetic element 14 in the preform 1. The order of machining of the different parts of the reconstruction can vary according to the equipment and the needs.

Machining of preform 1 can be used to form an inlay core, a dental post or an implant abutment. After machining at least a part of the long unidirectional fibers of the central portion 22 extend from one end to the other of the prosthetic element which has been formed by machining.

The calculation steps can be carried out by a computer, for example a computer.

As illustrated in FIG. 4, once the prosthetic element 14 has been formed by machining, it can be introduced into the dental canal as shown in FIG. 4. The coronal reconstruction bears against the dental wall above the box. pulp which allows for example a core inlay. Coronoradicular reconstruction can be without a crown.

Advantageously, the reference fiber 25 is made of a material which can be etched preferentially with respect to the material of the matrix and to the other first fibers 7. In a completed corono-radicular reconstruction, it is possible, later, to preferentially etch the corono-radicular reconstruction A in order to access an infected apex. The preferential etching can be done by means of a reamer using a material having a hardness lower than the hardness of the other first fibers 7 and of the resin. This configuration does not exist in the prosthetic elements produced by means of machinable preforms.

The machining of the preform 1 to form a coronal-radicular reconstruction makes it possible to form a reconstruction whose three-dimensional shape is defined from the impression of the tooth to be repaired and/or from a calculated impression of the tooth to be repaired. replace. The three-dimensional shape of the reconstruction is specific to adapt as best as possible to the dentinal wall 15.

The machining defines the shape of the tooth and therefore the dimensions with respect to the reference fiber 25 perpendicular to the first direction Y. The machining also defines the height of the prosthetic element 14 according to the first direction Y as well as the height of the root anchor 11 and of the coronary reconstitution 13 by removing part of the two opposite ends of the preform 1 . By using preforms that are taller than conventional build-ups, the same preform can be adapted to a large number of repair configurations.

By using the marker 18 present on the preform 1 and indicating the characteristics of the preform 1, in particular the position of the interface between the pulp box 12 and the root anchorage 11 and the position of the interface between the pulp box 12 and the crown build-up 11, the machining equipment is able to machine the preform 1 to define its height as well as the height of the root anchor 11 and the height of the crown build-up 13.

Figures 7 and 8 illustrate a machinable element which comprises several machinable preforms 1 described previously. The manufacturing process makes it possible to produce a single preform 1 but it also makes it possible to produce several preforms 1 . Depending on the case, the preforms 1 are identical or different. The multiple machinable preforms 1 are formed together such that the machinable member forms a monolithic member that contains the multiple preforms. The different lattices can be formed simultaneously or successively. A single step of adding the first resin 5 is preferably carried out. The multiple preforms are mechanically connected to each other by the first resin 5 so as to form a one-piece element which facilitates handling and avoids damaging the edges of the preform 1. In a particular embodiment, the preforms 1 are mechanically connected by one or more fibers with the exception of the first fibers 7.

The machinable preforms 1 are singled out from each other by a step of etching the machinable element. Preferably, the etching device detects the presence of a reference fiber 25 representing the center of the preform 1 and it etches the machinable element to isolate the machinable preform 1.

When the preforms are formed by fixing the first fibers 7 on a support before the installation of the other fibers forming the mesh, the support is preferentially removed from the preform 1 before carrying out the machining. When several preforms 1 are produced on the same support, the support is preferentially separated from the machinable system before singling out the multiple machinable preforms 1 by cutting out the machinable system.

It is advantageous for the first fibers 7 used in the central portion 22 to be thinner than the first fibers 7 used in the intermediate portion 23, themselves thinner than the first fibers 7 used in the peripheral portion 24.

Claims

35 Claims

1. Method for manufacturing at least one machinable preform (1) for a prosthetic element (14) comprising the following steps:

- providing a three-dimensional mesh formed by a plurality of fibers (7, 19, 21) and a plurality of attachment points (6), each fiber of the plurality of fibers (7, 19, 21) comprising at least one attachment point (6) with another fiber of the plurality of fibers (7, 19, 21) so that the mesh maintains its shape when subjected to a first value of stresses, the mesh defining a porous structure, the plurality of fibers (7, 19, 21) comprising a plurality of first fibers (7) arranged parallel to each other and oriented in a first direction (Y),

- filling the mesh with a first resin (5), the first resin (5) applying the first stress to the mesh,

- polymerizing the first resin (5), the lattice forming at least two distinct zones (8, 9, 10) arranged successively along the first direction (Y) and having different mechanical properties in response to a first stress perpendicular to the first direction (Y).

2. A method of manufacturing at least one machinable preform (1) according to claim 1 wherein the plurality of attachment points (6) is formed by a weld between two fibers, a weld between two fibers, a knot between two fibers , a fixing between two fibers by means of a second resin in the polymerized state.

3. A method of manufacturing at least one machinable preform (1) according to one of claims 1 and 2 successively comprising the installation of the plurality of first fibers (7) on a support, the first fibers (7) being parallel between them and the realization of the other fibers of the plurality of fibers (7, 19, 21) to form the mesh.

4. A method of manufacturing at least one preform (1) machinable according to claim 1 wherein the lattice is formed by a single piece by means of an additive manufacturing process or by a subtractive manufacturing process. 36

5. A method of manufacturing at least one preform (1) machinable according to any one of the preceding claims wherein the plurality of fibers (7, 19, 21) comprises a reference fiber (25) having a color different from the first fibers (7) and the first resin (5), the reference fiber (25) being parallel to the first fibers (7).

6. A method of manufacturing at least one machinable preform (1) according to any one of the preceding claims, in which the lattice forms at least a central portion (22), an intermediate portion (23) and a peripheral portion (24) , the intermediate portion (23) surrounding the central portion (22) and separating the central portion (22) and the peripheral portion (24), the volume content of first fibers (7) in the central portion (22) being greater than the volume content of first fibers (7) in the intermediate portion (23), itself greater than the volume content of first fibers (7) in the peripheral portion (24).

7. A method of manufacturing at least one machinable preform (1) according to the preceding claim wherein, in the central portion (22), the volume content of first fibers (7) is greater than the total volume content of the other fibers of the plurality of fibers (7, 19, 21).

8. A method of manufacturing at least one machinable preform (1) according to any one of the preceding claims, in which the first fibers (7) extend continuously from a first face (2) to a second face (3 ) opposite, the first face and the second face being opposite in the first direction (Y).

9. A method of manufacturing at least one machinable preform (1) according to any one of the preceding claims, in which the first resin (5) has a Young's modulus lower than the Young's modulus of the lattice in the first direction (Y) and in a direction perpendicular to the first direction (Y).

10. A method of manufacturing at least one machinable preform (1) according to any one of the preceding claims further comprising forming at least one mark (18) on the at least one side face (4) of the machinable preform (1) at the interface between two distinct zones (8, 9, 10) of the at least two distinct zones (8, 9, 10).

11 . Method of manufacturing at least one machinable preform (1) according to any one of the preceding claims, in which the plurality of fibers (7, 19, 21) comprise second fibers (19) extending perpendicularly to the first direction ( Y) in the form of a plurality of layers (20) of second fibers (19).

12. A method of manufacturing at least one machinable preform (1) according to claim 11, in which each first fiber (7) is attached to at least one sheet (20) of the plurality of sheets (20) by an attachment point (6) of the plurality of fixing points (6).

13. A method of manufacturing at least one machinable preform (1) according to one of claims 11 and 12 wherein the at least two distinct zones (8, 9, 10) are three zones arranged consecutively in the first direction (Y) and in which the three zones (8, 9, 10) are distinguished from each other by at least one of the following parameters:

- the volume percentage of second fibers (19),

- the distance between two layers (20) of successive second fibers (9),

- the reinforcement of the layers (20) of second fibers (9) when the layers (20) are woven,

- the chemical composition of the second fibers (19) forming the sheets (20) of second fibers (19),

- the orientation of the warp and weft fibers when the layers (20) of second fibers (19) are woven layers (20).

14. A method of manufacturing at least one machinable preform (1) according to any one of the preceding claims comprising at least the following steps:

- provide an impression of a tooth to be repaired,

- calculating the dimensions of three zones (8, 9, 10) arranged successively along the first direction (Y) and representative of a root anchorage (11), a pulp box (12) and a coronal reconstruction (13 ),

- define the dimensions of the central portion (22) perpendicular to the first direction (Y), the dimensions of the central portion (22) being chosen greater than the dimensions of the root anchoring zone (11) perpendicular to the first direction ( Y),

- define the dimensions of the layers (20) of second fibers (19) so as to extend beyond the dimensions of the root anchor area (8), the pulp box area (9) and the core build-up area (10) perpendicular to the first direction (Y) and define the configurations layers (20) of fibers (19) along the first direction (Y) to define the at least three zones (8, 9, 10),

- form the three-dimensional lattice.

15. A method of manufacturing at least one machinable preform (1) according to any one of the preceding claims comprising the manufacture of a plurality of machinable preforms (1) rigidly connected to each other in the form of a support, the preforms (1) of the plurality of machinable preforms (1) being mechanically connected to one another at least by the polymerized first resin (5).

16. A method of manufacturing at least one machinable preform (1) according to the preceding claim, in which the preforms (1) of the plurality of machinable preforms (1) are mechanically connected together by fibers of the plurality of fibers (19 , 21) with the exception of the first fibers (7).

17. A method of manufacturing at least one machinable preform (1) according to claims 15 or 16 comprising a step of singling out each of the machinable preforms (1) by etching the support.

18. Machinable preform (1) comprising a three-dimensional mesh embedded in a first resin (5) in the polymerized state, the three-dimensional mesh being formed by a plurality of fibers (7, 19, 21) and a plurality of fixing points ( 6), each fiber of the plurality of fibers (7, 19, 21) having at least one attachment point (6) with another fiber of the plurality of fibers (7, 19, 21), the plurality of fibers (7 , 19, 21) comprising a plurality of first fibers (7) arranged parallel to each other and oriented in a first direction (Y), the plurality of attachment points (6) having an interface with the first resin (5), in which the first fibers (7) continuously connect two opposite faces (2, 3) along the first direction (Y), and in which the lattice forms at least two distinct zones (8, 9, 10) arranged successively along the first direction (Y ) and having different mechanical properties in response to a first perpend icular to the first direction (Y). 39

19. Machinable preform (1) according to the preceding claim, in which the mesh forms three zones (8, 9, 10) arranged consecutively in the first direction (Y).

20. Method for manufacturing a prosthetic element (14) comprising at least the following steps:

- providing a machinable preform (1) according to claims 18 and 19,

- provide an impression of a tooth to be repaired,

- engraving the machinable preform (1) to reproduce the dimensions of the impression of the tooth to be repaired and to define at least one root anchorage (11) and a crown reconstruction (13), respectively from an anchoring zone root canal (8) and a coronal reconstruction zone (10).

21 . Process for producing a coronal-radicular restoration comprising the following steps:

- providing a prosthetic element (14) obtained by means of a manufacturing process according to the preceding claim,

- installing the prosthetic element (14) in a dental canal of a laboratory model.

22. Coronal-radicular restoration of a laboratory model, in which the prosthetic element (14) comprises:

- a three-dimensional mesh embedded in a first resin (5) in the polymerized state, the three-dimensional mesh being formed by a plurality of fibers (7, 19, 21) and a plurality of fixing points (6), each fiber of the plurality of fibers (7, 19, 21) comprising at least one attachment point (6) with another fiber of the plurality of fibers (7, 19, 21), the plurality of fibers (7, 19, 21) comprising a plurality of first fibers (7) arranged parallel to each other and oriented along a first direction (Y), the plurality of attachment points (6) having an interface with the first resin (5), in which the first fibers (7) connect two opposite faces (2, 3) of the prosthetic element (14) continuously from a root anchorage (11) to a coronal reconstruction (13) in the first direction (Y), and in which the mesh has mechanical properties different between the root anchor (11) and the coronal reconstruction zone (13) disposed are successively in a first direction (Y), the different mechanical properties being in response to a first stress perpendicular to the 40 first direction (Y).