CAD / CAM-machinable block for the production of a dental prosthesis element, in particular a fiber inlay core

Description

[0001] The invention relates to a block intended for CAD / CAM machining machines or more generally a support block machinable by CAD / CAM for the manufacture of dental prosthetic elements such as crowns, bridges, inlay-cores (post + false stump), posts, implant pillars (abutment). It also relates to a method for manufacturing said block.

[0002] The machining of dental prosthetic elements, specifically crowns and bridges, using CAD / CAM (Computer Aided Design and Manufacturing) from preforms is well known. This technology, also known as CAD / CAM, was described, for example, in document EP 040165 B1. The technology has since evolved, both in terms of CAD / CAM equipment and in terms of the composition of the preforms.

[0003] There are basically 2 types of preforms.

[0004] The first type is in the form of "blocks" of generally parallelepiped shape. In this case, the blocks are fixed to the articulated arm exposing the preform to the machining tool, by means of a mandrel secured to the block. It is this type of preform which is concerned by the invention.

[0005] The second type of preform is in the form of a "disc" within which the prosthetic elements are machined. In this case, the disc does not have a specific arrangement allowing it to be fixed to the articulated arm. It is simply positioned in a footprint of its shape that the articulated arm has.

[0006] The invention will subsequently be more particularly described in relation to a CAD / CAM block used for the manufacture of fiber inlay-cores.

[0007] The inlay-core is a single-piece piece consisting of a post topped with a false stump. It is made of metal, more rarely ceramic. It is formed from a single piece, which is why it is called "inlay-core or post & core." It is therefore made of the same material. The inlay-core serves as a support for a reconstruction of a devitalized tooth.

[0008] In terms of manufacturing, metal inlay-cores can be obtained using the so-called lost wax casting technique in the prosthesis laboratory or, more rarely, by CAD / CAM machining from a steel or titanium disc.

[0009] There are also fiber inlay cores, which can be machined from a disc of the type mentioned above and as described in EP 16 798 238, in which cells are formed. Each cell is filled with a composite material in which vertical fibers are embedded. The CAD / CAM machine machines the inlay cores directly in the composite material.

[0010] It is also possible to produce composite tenons or inlay cores from a CAD / CAM block. In this case, the insert in which the inlay core is machined, hereinafter referred to as the "insert," must be attached to a metal mandrel. To do this, the metal mandrel is glued to one of the faces of the insert.

[0011] The industrial manufacturing of these blocks makes the machining solution expensive. Indeed, the inserts must first be covered with resin, then assembled by gluing to the previously machined metal mandrels. The cost of the metal mandrel, typically made of brass, aluminum, or stainless steel, combined with the numerous manufacturing steps, leads to a high production cost. Furthermore, the blocks available on the market have standard sizes, for example 14mm x 18mm x 14mm (width x length x height). These blocks are used for the manufacture of both crowns and tenons. However, since a crown occupies a much larger volume than a tenon, there is excessive overconsumption of material in the case of the manufacture of a tenon and therefore an unnecessary additional cost.

[0012] WO 2009 / 070470 A1 describes a crosslinkable preform intended to be machined by CAD / CAM. The preform comprises an insert made of two SMC (self-supporting malleable curable) materials corresponding to the composition of dentin and enamel. The block is supplied with a rod that can take the form of a mandrel, which can then be crosslinked in the event of machining after fixing the block on a machine. The rod is a priori supplied separately and probably secured to the block by any known means, which makes the product complicated to handle. Nothing is indicated concerning the material constituting the rod.

[0013] Therefore, the problem that the invention aims to solve is that of developing a CAD / CAM block capable of being fixed to the CAD / CAM machining machine by means of a mandrel, which does not have the above drawbacks, in particular which is easy to manufacture and therefore inexpensive.

[0014] The second problem that the invention aims to solve is that of developing a CAD / CAM block of standard size but whose content of material constituting the insert is a function of the prosthetic element to be manufactured.

[0015] The Applicant has developed a dental CAD / CAM machining block for a prosthetic element, the mandrel and the insert coating material of which are made of a single cross-linked material.

[0016] More specifically, the invention relates to a block for CAD / CAM machining of a dental prosthetic element comprising: an insert in which said prosthetic element is machined, a polymeric layer covering at least part of the surface of said insert, a mandrel secured to the polymeric layer.

[0017] The block is characterized in that the mandrel is made of a material identical to that of the polymer layer and in that the mandrel and the polymer layer are crosslinked.

[0018] The term "identical material" means a material that has the same composition as the polymer layer.

[0019] In practice, said material is a thermosetting polymer, advantageously chosen from the group comprising polyurethane (PU), methacrylic resins or a thermoplastic polymer chosen from the group comprising polycarbonate (PC), polyoxymethylene or polyacetal, (POM) polymethylmethacrylate (PMMA), polyurethane (PU), polyamide (PA). This list is not exhaustive insofar as other polymers which are both mechanically resistant so that the mandrel does not break and compatible with dental applications can be used. Advantageously, the above polymers and in particular PC, PMMA, PU or PA are reinforced by random fibers, for example glass fibers. Preferably, the random fibers represent from 10 to 50% by weight, advantageously 30% by weight of the material.

[0020] These inserts can be cylindrical, cubic or rectangular parallelepiped in shape depending on the desired applications.

[0021] According to an essential characteristic, the CAD / CAM block of the invention comprises an insert of which at least part of the surface is covered with a crosslinked polymeric layer.

[0022] In a preferred embodiment, in particular when the insert is cubic or rectangular parallelepiped in shape, at least the face of the insert, called the "opening face", is not covered with the polymeric layer. The open face is in practice the face opposite the face of the insert on which the mandrel is fixed, the latter being covered according to the invention with a crosslinked polymeric layer.

[0023] In an advantageous embodiment, the insert is cubic or rectangular parallelepiped in shape and has only one face covered with the polymer layer, namely the face from which the mandrel emerges. This embodiment is particularly suitable for the manufacture of crowns or bridges which require a large volume of material constituting the insert.

[0024] In another embodiment, the insert is cubic or rectangular parallelepiped in shape and has 2 faces covered with the polymeric layer, respectively the face from which the mandrel emerges, and 1 face extending one side of the face from which the mandrel emerges. This embodiment is particularly suitable for the manufacture of posts, inlay cores or implant abutments which require a volume of material constituting the insert, less important than for the manufacture of crowns or bridges. The insert is therefore covered with a higher content of polymeric layer than that of the previous embodiment and contains a lower content of material constituting the insert, which thus reduces the cost compared to the blocks of the state of the art.

[0025] In another embodiment, the entire surface of the insert is covered by the polymeric layer. This may be the case, in particular, when the insert is cylindrical in shape. Preferably, the mandrel is in this case positioned in a direction orthogonal to that of the axis of the cylinder. Given the smaller volume of the insert, this embodiment will also be more suitable for the manufacture of posts, inlay cores and implant abutments.

[0026] In all cases, the polymer layer is advantageously overmolded onto the insert.

[0027] In practice, excluding the mandrel, the polymer layer represents between 10 and 50% by weight of the total weight of the block.

[0028] The insert can be made of metal or preferably a composite material.

[0029] The invention also relates to the use of the block previously described for machining dental prosthetic elements such as crowns, bridges, inlay-cores (post + false stump), posts, implant pillars (abutment).

[0030] In a first embodiment, the block of the invention is used for machining crowns and bridges. In this case, the composite material insert is typically composed of polymers, in particular methacrylic resins, advantageously crosslinked, reinforced by fillers such as silica, ceramic glass, radiopaque particles taken alone or in combination, well known in the dental field. These reinforcing fillers can represent up to 85% by weight of the insert. In practice, these inserts are manufactured by molding.

[0031] In the case of fiber inlay-core, fiber post, implant abutment, the composite material is composed of polymers, in particular of the epoxy, polyester, vinylester, methacrylic resin type, reinforced by long unidirectional fibers, in particular glass, quartz, silica, XRO fibers or generally any fibers with high mechanical performance. These fibers can represent up to 85% by weight of the insert material. In this case, the insert is obtained from profiles obtained for example by the pultrusion technique leading to crosslinked products. The profiles of cylindrical, square or rectangular section are then cut into several sections according to the desired height for the block.

[0032] Regardless of the type of insert, they then advantageously undergo mechanical treatment such as sandblasting or machining in order to obtain a rough surface promoting adhesion with the polymer layer. If necessary, a physicochemical treatment such as plasma-silanization can be applied to the inserts.

[0033] The invention also relates to a method for manufacturing the CAD / CAM block as previously described.

[0034] This process includes the following steps: prepare a mold having 2 hollow parts respectively a first part advantageously of cubic or parallelepiped shape extending on one of its sides by a second part in the shape of the mandrel, position the insert previously manufactured in the first part, inject a polymeric material into the mold, crosslink the polymeric material, demold the block.

[0035] In a first embodiment, the insert is positioned in the center of the first part and the material is injected into the entire remaining volume of the first part and into the entire volume of the second part. Under these conditions, the entire surface of the insert is covered with polymeric material. The insert may be parallelepipedal or cylindrical in shape.

[0036] In a second embodiment, the insert is of generally parallelepipedal shape and the material is injected into only part of the volume of the first part and into the entire volume of the second part. Under these conditions, the insert is positioned in the first part of the mold so that the polymeric material covers at least the face of the insert from which the mandrel emerges.

[0037] The inserts are advantageously inserts made of composite materials as described previously.

[0038] The invention and the advantages resulting therefrom will become clear from the following examples supported by the attached figures. [ Fig.1 ] There figure 1 is a representation of the block of the invention according to a first embodiment. Fig.2 ] There figure 2 is a representation of the block of the invention according to a second embodiment. Fig.3 ] There figure 3 is a representation of the block of the invention according to a third embodiment.

[0039] On the figure 1 , a block for CAD / CAM machining of a dental prosthetic element according to the invention is shown. It consists of an insert (1) which is in the form of a cylinder, a crosslinked polymer layer (2), for example made of PMMA and a mandrel (3). The polymer layer covers the entire surface of the insert and forms a cube. The mandrel (3) is made of a material identical to that of the polymer layer.

[0040] The insert is made of polymers such as epoxy, polyester, vinylester, methacrylic resin reinforced with long unidirectional fibers such as glass, quartz, silica, XRO fibers. The insert is made from profiles obtained using the pultrusion technique. The cylindrical section profiles are then cut into several sections according to the desired height for the block.

[0041] The manufacturing process is as follows: a mold is prepared having 2 hollow parts respectively, a first part of cubic shape extending on one of its sides by a second part in the shape of the mandrel, the cylindrical insert previously manufactured is positioned in the center of the first part, a polymeric material is injected into the mold so as to fill the entire remaining volume of the first part and the entire volume of the second part, the polymeric material is crosslinked, the block is demolded.

[0042] Under these conditions, the overmolding formed from the polymer layer is cubic in shape. The block thus obtained is particularly suitable for the manufacture of tenons, inlay cores and implant abutments for which the quantity of material constituting the insert is less.

[0043] On the figure 2 , a block according to a second embodiment is shown. It consists of an insert (1a) which is in the form of a cube, a crosslinked polymer layer (2), for example in PC and a mandrel (3). The polymer layer covers the face (first face) of the cube in contact with the mandrel and a face of the cube extending the first face.

[0044] The insert is made of polymers such as epoxy, polyester, vinylester, methacrylic resin reinforced with long unidirectional fibers such as glass, quartz, silica, XRO fibers. The insert is made from profiles obtained using the pultrusion technique. The square-section profiles are then cut into several sections depending on the desired height for the block.

[0045] The manufacturing process is as follows: a mold is prepared having 2 hollow parts respectively, a first part of cubic shape extending on one of its sides by a second part in the shape of the mandrel, the previously manufactured cubic insert is positioned in the first part of the mold so that the polymeric material covers the 2 faces of the insert mentioned above, a polymeric material is injected into the mold so as to fill the entire remaining volume of the first part and the entire volume of the second part, _ the polymeric material is crosslinked, the block is demolded.

[0046] The block thus obtained is particularly suitable for the manufacture of tenons, inlay cores and implant abutments for which the quantity of material constituting the insert is less.

[0047] On the figure 3, a block according to a third embodiment has been shown. It consists of an insert (1a) which is in the form of a cube, a crosslinked polymer layer (2), for example in PU, and a mandrel (3). Unlike the previous embodiment, the polymer layer only covers the face of the cube from which the mandrel emerges.

[0048] In this case, the composite material insert is typically composed of polymers, particularly methacrylic resins, reinforced with fillers such as silica, ceramic glass, radiopaque particles

[0049] The manufacturing process is as follows: a mold is prepared having 2 hollow parts respectively, a first part of cubic shape extending on one of its sides by a second part in the shape of the mandrel, a polymeric material is injected into the mold so as to fill the entire remaining volume of the first part and the entire volume of the second part, the polymeric material is crosslinked, the block is demolded.

[0050] The block thus obtained is particularly suitable for the manufacture of crowns and bridges for which the quantity of material constituting the insert is significant.

[0051] The invention and the advantages resulting therefrom are clearly evident from the preceding description. In particular, the advantage linked to the manufacture of the mandrel in a material identical to that of the polymeric layer covering the insert is noted, which makes it possible to drastically reduce costs without altering the handling of the block.

Claims

1. Block for CAD / CAM machining of a dental prosthetic component comprising: - an insert (1) in which said prosthetic component is machined, - a polymer layer (2) covering at least one surface of said insert (1), - a mandrel (3) integral with the polymer layer (2), characterized in that the mandrel (3) is made of an identical material to that of the polymer layer (2) and that the mandrel (3) and the polymer layer (2) are crosslinked.

2. Block according to Claim 1, characterized in that said material is a thermosetting polymer advantageously selected from the group comprising polyurethane (PU), methacrylic resin or a thermoplastic polymer advantageously selected from the group comprising polycarbonate (PC), polyoxymethylene or polyacetal (POM), polymethylmethacrylate (PMMA), polyurethane (PU), polyamide (PA).

3. Block according to any one of the preceding claims, characterized in that the material is reinforced by random fibres, preferably glass fibres.

4. Block according to Claim 3, characterized in that the random fibres represent from 10 to 50% by weight, advantageously 30% by weight, of the material.

5. Block according to any one of the preceding claims, characterized in that the insert is in the shape of a cube or rectangular parallelepiped and has 2 faces covered by the polymer layer, namely the face from which the mandrel emerges and 1 face extending one side of the face from which the mandrel emerges, respectively.

6. Block according to any one of Claims 1 to 4, characterized in that the insert is in the shape of a cube or a rectangular parallelepiped and has only 1 face covered by the polymer layer, namely the face from which the mandrel emerges.

7. Block according to any one of Claims 1 to 4, characterized in that the insert is cylindrical in shape and its entire surface is covered with a polymer layer.

8. Block according to Claim 7, characterized in that the mandrel is positioned in a direction orthogonal to that of the axis of the cylinder.

9. Use of the block according to any one of Claims 1 to 8 for machining dental prosthetic components such as crowns, bridges, inlay-cores (post + core), posts, implant abutments.

10. Method for manufacturing the block which is the subject of any one of the preceding claims, characterized in that it comprises the following steps: - preparing a mould comprising 2 hollow parts, respectively, a first part in the shape of a cube or parallelepiped extending on one of its sides into a second part shaped as the mandrel, - positioning the previously manufactured insert in the first part, - injecting a polymer material into the mould in such a manner as to fill the 2 parts, - crosslinking the polymer material, - demoulding the block.