Dental preform, method for manufacturing one such preform, and method for manufacturing dental prosthesis from one such preform

Abstract

To provide a dental preform having an elastic modulus gradient between a central portion and a peripheral portion so as to represent mechanical features of natural tooth.SOLUTION: A dental preform includes a central portion formed by a plurality of first wire-like elements extending mainly in a first direction and first resin. An annular peripheral portion passes surroundings of the central portion perpendicularly to the first direction. The peripheral portion is provided with a second wire-like element and second resin. The peripheral portion is provided with a plurality of layers arranged on one another perpendicular to the first direction. Each of the layers has at least one winding formed by at least one of second wire-like elements. At least one second wire-like element indicates a longitudinal direction off-set with respect to the first direction by an angle comprised between 10° and 80° or between 100° and 170°. Second wire-like elements of two consecutive layers show opposite orientations.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to a dental preform, a method for manufacturing such a dental preform, and a method for manufacturing a dental prosthesis from such a dental preform.

Background Art

[0002] It is known to form at least part of a dental prosthesis from a machined dental preform. The dental preform is machined by any suitable means, and preferably by CAD-CAM technology. Various types of dental preforms are commercially available with substantially uniform mechanical properties from one end to the other end of the preform.

[0003] However, it should be noted that the mechanical properties of such preforms are far from those of natural teeth, which causes fit problems when dental prostheses are incorporated. It has been observed that current composite materials, specifically particle-based composites, may be inappropriate for reproducing the function of natural teeth. The same is true for ceramic preforms, for example those made from lithium disilicate or zircon. This problem also exists in hybrid ceramics, which are composite materials having a main lattice and a secondary lattice. A secondary lattice made from a polymer is infiltrated into the main lattice made from a ceramic. The two lattices are completely overlapped in a tile-like manner with each other. The ceramic-polymer double lattice structure is ideally designed to combine the good properties of ceramics and composites. However, the ceramic main lattice is still rigid and brittle. Also, it is hardly deformable and thus does not allow reproducing the mechanical properties of natural teeth. The toughness of this hybrid material is considered to be low, thus limiting its interest.

[0004] It is also possible to create tailor-made dental preforms with mechanical properties configured to fit the dimensional constraints of the tooth to be replaced. However, this process is time-consuming and relatively cumbersome.

[0005] Therefore, there is a need to create dental preforms that better address the mechanical properties of teeth while also being easy to implement. [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] One objective of the present invention is to eliminate these drawbacks, and more specifically, to provide a dental preform having an elastic modulus gradient between its central portion and its peripheral portion in order to better reproduce the mechanical properties of a natural tooth. [Means for solving the problem]

[0007] These drawbacks are, - A central portion formed of a plurality of first wire-like elements and a first resin, wherein the first wire-like elements extend mainly in a first direction, and the first resin mechanically connects the first wire-like elements to each other. - A peripheral portion that takes the shape of a ring around a central portion perpendicular to a first direction, wherein the peripheral portion comprises a second wire-like element and a second resin, the second resin mechanically bonding the second wire-like element to each other, and the first wire-like element and the second wire-like element are mechanically bonded to each other by at least the first resin and the second resin, and Equipped with, The periphery comprises multiple layers arranged perpendicular to each other with respect to a first direction, and the layers pass around the central portion. Each layer has at least one coil formed by at least one of the second wire-like elements, and at least one of the second wire-like elements has a longitudinal direction offset from the first direction by an angle between 10° and 80°, or between 100° and 170°. The second wire-like element of the two consecutive layers exhibits opposite orientations. Dental preforms tend to overcome the issue where the second wire-like element of each layer does not belong to a cloth or woven element.

[0008] According to one feature of the present invention, the central portion has a wire-like element in which the majority in terms of volume is the first wire-like element.

[0009] In the preferred method, the central portion comprises only the first wire-like element and the first resin.

[0010] In certain embodiments, the peripheral portion has an elastic modulus gradient that increases as it moves away from the central portion perpendicular to the first direction.

[0011] Advantageously, the peripheral portion exhibits an content of second wire-like elements that increase linearly as they move away from the central portion perpendicular to the first direction, in order to form an elastic modulus gradient.

[0012] In certain embodiments, particles are added to the second resin. The peripheral portion exhibits a ratio of the content of the second wire-like element to the particle content, which increases radially away from the central portion perpendicular to the first direction, in order to form an elastic modulus gradient.

[0013] Preferably, the ratio of the second wire-like element content to the particle content increases inversely proportional to the distance to the center portion in order to form an elastic modulus gradient.

[0014] In another developmental form, at least some of the layers further hold sheets selected from cloth, woven elements, strips, or braids, the sheets located below or above the second wire-like elements of the aforementioned layers.

[0015] Advantageously, the sheet extends in a first direction from one end of the dental preform to the other, extending across all layers, the sheet takes the shape of a helical curve in a cutting plane perpendicular to the first direction, and in an observation direction perpendicular to the first direction, the thickness of the sheet and the thickness of the second wire-like element alternate, oriented from the central portion to one end of the peripheral portion.

[0016] In the preferred method, multiple coaxial tubes are formed by multiple layers of sheets from the interface with the central portion to the outer wall portion of the periphery.

[0017] In one preferred embodiment, each layer comprises several second wire-like elements wound around a central portion.

[0018] Another object of the present invention is to provide a manufacturing method that enables the easy formation of preforms exhibiting better-mastered mechanical properties. This problem is, - A step of preparing a mandrel extending in a first direction, - A step of forming a ring-shaped marginal portion around a mandrel perpendicular to a first direction, wherein the marginal portion has a plurality of layers passing around the mandrel, the layers are arranged around each other perpendicular to the first direction, and each layer comprises at least one second wire-like element and a second resin, the second resin mechanically bonding the second wire-like elements to each other in the marginal portion. Equipped with, At least one second wire-like element in each layer has a longitudinal direction that is offset from the first direction by an angle between 10° and 80°, or between 100° and 170°. At least one second wire-like element in two consecutive layers exhibits opposite orientations. At least one second wire-like element in each layer does not belong to a cloth or woven element, The mandrel is a central part formed by a plurality of first wire-like elements and a first resin, the first wire-like elements mainly extend in a first direction, the first resin mechanically couples the first wire-like elements to each other, and the first wire-like elements and the second wire-like elements are coupled to each other by at least the first resin and the second resin, or the mandrel is removed to define an empty region in the edge portion, and the empty region is filled with a plurality of first wire-like elements and the first resin, the first wire-like elements mainly extend in the first direction, and the first wire-like elements and the second wire-like elements are coupled to each other by at least the first resin and the second resin. It tends to be solved by a method for manufacturing a dental preform.

[0019] Advantageously, two consecutive layers share at least one second wire-like element. The winding is formed by a honeycomb coil, and preferably, at least one second wire-like element extends continuously across all layers of the edge portion.

[0020] In a preferred manner, each layer further comprises a sheet formed by a cloth or a woven element, the weft or quasi-weft thread of which extends in the first direction, the sheet extends continuously across a plurality of layers, and the sheet takes the form of a helix in a cutting plane perpendicular to the first direction.

[0021] In a preferred embodiment, the method includes at least the step of cutting an assembly formed by a central portion and an edge portion perpendicular to the first direction to determine the dimension of the dental preform in the first direction.

[0022] Another object of the present invention is to provide a method for manufacturing a dental prosthesis whose mechanical performance is better operated. This problem is - the step of preparing a dental preform according to any one of the above-described configurations, and - A step of cutting a dental preform, wherein a part of the edge portion is completely removed to reach a central portion designed to form a root canal anchorage, and another part of the edge portion is partially removed to form a crown portion of a dental prosthesis according to a predetermined shape. It tends to be solved by a method of manufacturing a dental prosthesis comprising.

[0023] Preferably, the method includes a step of cutting the dental preform perpendicular to a first direction before the cutting is performed to determine the dimensions of the dental preform in the first direction.

[0024] Other advantages and features are given for the purpose of showing only relatively limited examples and will become more clearly apparent from the following description of specific embodiments and implementation modes of the present invention shown in the accompanying drawings.

Brief Description of the Drawings

[0025] [Figure 1] A diagram schematically showing a perspective view of a dental preform. [Figure 2] A diagram schematically showing a perspective view of a dental preform fitted into a gripper. [Figure 3] A diagram schematically showing another perspective view of a dental preform fitted into a gripper according to another embodiment. [Figure 4] A diagram schematically showing a more detailed view of the central portion of a dental preform. [Figure 5] A diagram schematically showing the step of winding a second wire-like element around to form an edge portion of a dental preform. [Figure 6] A diagram schematically showing a cross-sectional view of a dental preform. [Figure 7] A diagram schematically showing a view of an apparatus for manufacturing a dental preform.

Mode for Carrying Out the Invention

[0026] Figures 1, 2, and 3 show a dental preform 1. The dental preform 1 has a central portion 2 and a peripheral portion 3. The dental preform 1 may be a dental preform to be machined, or a general-purpose preform that will be cut to form a dental preform to be machined. The preform is made from a composite material comprising at least one resin and at least one wire-like element.

[0027] Figure 4 shows a more detailed view of the dental preform 1, specifically the central portion 2. The central portion 2 comprises a plurality of first wire-like elements 4 and a first resin 5. The first wire-like elements 4 extend mainly in the first direction AA. The first resin 5 mechanically connects the first wire-like elements 4 to one another.

[0028] The first wire-like element 4 has first wire-like elements 4 oriented primarily in a first direction AA, and preferably parallel to each other. Preferably, the first wire-like elements 4 extend continuously in the first direction AA from one end of the preform to the other end, facilitating the transmission of force across the height of the central portion 2. The first wire-like element 4 may comprise unidirectional yarn, woven elements, fabric, strips, or braids. It is also possible to combine some of these elements, for example, yarn and braids. The woven elements, fabric, strips, or braids may be formed from several yarns or fibers.

[0029] The thread may be made from silica or an organic material. Preferably, the thread is made from a material selected from polyethylene, polyetheretherketone PEEK, and carbon. The same may apply to fibers. In the preferred configuration, the first wire-like element 4 extends continuously across the entire height of the dental preform 1, i.e., in the first direction AA.

[0030] In the preferred configuration, the first resin 5 is preferably a polymer resin loaded with particles, preferably microparticles and / or nanoparticles. The threads, fibers, cloths, strips, braids and other elements forming the first wire-like elements 4 may be coated with the impregnating resin. The impregnating resin may be the same as or different from the first resin 5. The impregnating resin and the first resin 5 are chemically compatible to ensure mechanical bonding between the first wire-like elements 4. The resin is preferably a thermosetting resin.

[0031] The central portion 2 may have any shape in its cutting plane perpendicular to the first direction AA. Preferably, the central portion 2 has a circular cross-section.

[0032] The central portion 2 has several first wire-like elements 4 that exhibit a higher modulus of elasticity than the first resin 5 in the first direction AA. The central portion 2 may also present additional wire-like elements having a hardness lower than the first wire-like elements 4 and the first resin 5 in order to define a preferential etching area and thereby facilitate intervention up to the infected apex.

[0033] The central portion 2 is advantageous in that it comprises a first wire-like element 4, which is the majority in terms of volume compared to any other wire-like element, in order to better transmit force.

[0034] It is advantageous for the central portion 2 to consist only of the first wire-like element 4 and the first resin 5. The force applied to the central portion 2 is transmitted more effectively.

[0035] The periphery portion 3 completely surrounds the central portion 2 perpendicular to the first direction AA. The periphery portion 3 forms a ring, and the central portion 2 is filled inside it.

[0036] The edge portion 3 comprises a second wire-like element 6 and a second resin 7. The second resin 7 mechanically connects the second wire-like elements 6 to each other. The first resin 5 and the second resin 7 mechanically connect the first wire-like element 4 to the second wire-like element 6.

[0037] The marginal portion 3 comprises multiple layers arranged on top of each other from the central portion 2 perpendicular to the first direction AA and preferably to the outer wall portion of the dental preform 1. The layers pass just around the central portion 2. In a preferred configuration, the layers comprise at least one second wire-like element 6 and one or more turns of the second resin 7 around the central portion 2. At least one second wire-like element 6 makes at least 360° turns around the central portion 2 when observed in the first direction AA. In a preferred embodiment, the second wire-like element 6 takes the form of a helix making several 360° turns around the central portion 2 and extends continuously from one end to the other end of the dental preform 1 in the first direction AA. Advantageously, the second wire-like element 6 makes at least two 360° turns around the central portion 2. Preferably, the second wire-like element 1 exhibits a constant or substantially constant winding pitch throughout the height of the dental preform 1, i.e., in the first direction AA.

[0038] Each layer, one or more second wire-like elements 6, have a longitudinal direction offset from the first direction AA by an angle between 10° and 80°, or between 100° and 170°. As the second wire-like elements 6 wind 360° around the central portion 2, the second wire-like elements 6 shift in one direction or another in the first direction AA. In the embodiment shown in Figure 5, the angle between the longitudinal direction (line BB) of the second wire-like element 6 and the first direction AA while winding is between 10° and 80°. In this configuration, with each winding around the central portion 2, the second wire-like element 6 shifts to the right. In the next and previous layers, the angle between the longitudinal direction of the second wire-like element 6 and the first direction AA while winding is between 100° and 170°, corresponding to a second wire-like element 6 whose longitudinal axis points in the opposite direction to the longitudinal axis of the previous layer. With each winding of the central portion 2, the second wire-like element 6 shifts to the left. The winding direction is reversed between the two consecutive layers. The use of the second wire-like element 6 with reversed orientation in the two consecutive layers allows the second wire-like element 6 of the two consecutive layers to define a mesh when observed perpendicular to the first direction AA.

[0039] Each layer contains at least one second wire-like element 6, such as a thread, fiber, strip, or braid, extending in a first direction AA from one end to the other of the dental preform 1 at the margins. At least one second wire-like element 6 is wound multiple times around the central portion 2. Depending on the layer, the coil is wound in the opposite direction around the first direction AA. In the preferred configuration, in each layer, the second wire-like element 6 extends continuously in the first direction AA from one end to the other of the dental preform 1, forming a winding around the central portion 2.

[0040] It is advantageous for the second wire-like element 6 to be wound around the central portion 2 at least five times.

[0041] One or more second wire-like elements 6 in each layer do not belong to the fabric or woven elements. One or more second wire-like elements 6 in each layer merely define a spiral around the central portion 2. In the preferred method, the second wire-like elements 6 are joined only by resin in the first direction AA. There are no weft or quasi-weft threads to join them together, as in the case of woven elements.

[0042] The second wire-like element 6 is wound around the central portion 2 to form multiple windings. The multiple windings take the form of a stack of coiled windings around the central portion 2. The stack of coiled windings comprises several layers of windings arranged on top of each other in a radial direction perpendicular to the first direction AA.

[0043] The second wire-like element 6 defines a plurality of holes extending to the central portion 2 in a direction perpendicular to the first direction AA. The holes are filled with the second resin 7. The holes are defined by a plurality of overlapping coil-like windings that are preferably diamond-shaped when viewed perpendicular to the first direction AA.

[0044] The second wire-like element 6 may comprise a unidirectional yarn, a woven element, a cloth, a strip, or a braid. The yarn may be silica yarn or a yarn made from an organic material. Preferably, the yarn is made from a material selected from polyethylene, polyetheretherketone (PEEK), and carbon. The second wire-like element 6 may have the same chemical composition as the first wire-like element 4, or it may have a different chemical composition from the first wire-like element 4.

[0045] In the preferred configuration, the second resin 7 is a polymer resin loaded with particles 7a, preferably microparticles and / or nanoparticles. Yarns, fibers, fabrics, strips, braids, and other elements forming the second wire-like elements may be coated with the second impregnation resin. The second impregnation resin may be identical to or different from the second resin 7. The second impregnation resin and the second resin 7 are chemically compatible to ensure mechanical bonding between the second wire-like elements 6. The resin is preferably a thermosetting resin.

[0046] The formation of several annular layers, arranged around each other and mechanically connected to one another by the second resin 7, allows for efficient adjustment of mechanical properties in a radial or substantially radial manner, perpendicular to the first direction AA. Because the thickness of the second wire-like element is small, it is possible to create numerous windings around the central portion 2 to form the marginal portion 3 while remaining within the lateral dimensions of the tooth to be treated. Thus, it is possible to easily fabricate a dental preform 1 whose mechanical properties are manipulated radially, i.e., according to the distance it is positioned relative to the central portion 2.

[0047] Adjusting the winding characteristics in each layer from the interface with the central portion 2 to the outer wall portion of the peripheral portion 3 provides great freedom to adjust the mechanical properties in a radial or substantially radial manner.

[0048] Each layer is formed by at least one or more second wire-like elements 6 wound around the central portion 2 and, where applicable, around the lower layer. The coiled winding present in each layer is defined by at least the following technical characteristics:

[0049] - Number of second wire-like elements 6 wrapped around a certain layer - Intrinsic technical properties of one or more second wire-like elements 6, used together with, for example, elastic modulus, cross-section, chemical composition, and surface condition. - The winding tension of each wrapped wire-like element - The winding pitch when wound 360°, i.e., the offset in the first direction AA, which corresponds to the angle between the first direction AA and the longitudinal axis of the second wire-like element. - Whether or not impregnating resin is used in each wire-like element, and, if impregnating resin is present, the composition of the impregnating resin.

[0050] The mechanical properties of the layer depend on the winding characteristics of the layer and the composition of the second resin 7.

[0051] To form a dental preform 1 that exhibits mechanical properties close to those of a natural tooth, it is advantageous to form a marginal portion 3 having an elastic modulus gradient in a direction perpendicular to a first direction AA. The elastic modulus in the marginal portion 3 starts at the interface with the central portion 2 and increases as it moves away from the central portion 2. Advantageously, the elastic modulus is in the first direction AA and / or in a direction perpendicular to the first direction AA.

[0052] In the preferred method, the modulus gradient of the edge portion 3 increases linearly from the interface with the central portion 2 to at least 50% of the thickness of the edge portion 3, more preferably beyond at least 75% of the thickness, or even over the entire thickness of the edge portion 3. In the even more preferred method, the modulus gradient of the edge portion 3 increases linearly from the interface with the central portion 2 to at least 50% of the thickness of the edge portion, more preferably beyond at least 75% of the thickness, or even over the entire thickness of the edge portion 3.

[0053] In one advantageous embodiment, the modulus of elasticity exceeds 80 GPa at the outer edge of the peripheral portion 3, and is less than 20 GPa in the immediate vicinity of or within the central portion 2. In the preferred method, the modulus of elasticity gradient extends beyond at least 40 GPa.

[0054] To mitigate the propagation of microcracks from the outer surface of the dental preform 1 towards the central portion 2, it is advantageous to continuously decrease the elastic modulus value in the direction of the central portion 2, preferably exceeding 40 GPa and more preferably decreasing linearly.

[0055] To obtain an elastic modulus gradient across several layers, the winding characteristics are modified from one layer to another, or from one set of layers to another.

[0056] The modulus gradient can be obtained by modifying at least one of the following parameters.

[0057] - Number of second wire-like elements within the layer - Winding pitch value - Chemical composition of the second resin 7 - Winding tension of the second wire-like element 6 - Cross-sectional and / or chemical composition of one or more wire elements forming the second wire element 6 - Surface condition of the second wire-like element 6.

[0058] Modification of the chemical composition of the second resin 7 or the second impregnation resin may also be a modification of the filler content, such as the microparticle content, nanoparticle content, or whisker content. Modification of the chemical composition may also be a modification of the chemical composition of the filler. Modifications made to the second resin 7 have the effect of modifying its mechanical properties in the direction perpendicular to the first direction AA and in the first direction. For example, to increase the elastic modulus value when moving away from the center portion 2, it is possible to continuously increase the filler content in the layer (without changing other parameters) when moving away from the center portion 2. It is also possible to modify several parameters between two consecutive layers, such as the winding pitch and the filler content.

[0059] In one embodiment, the layer is formed by several windings produced from the same yarn wound around the central portion 2. In an alternative embodiment, several different yarns are wound around the central portion 2. The yarns of the same single layer may have the same cross-section and composition. To use yarns with different mechanical properties, it is also possible to provide yarns with the same composition but different cross-sections. It is even possible to form layers with yarns having different mechanical properties by using yarns with the same or different cross-sections and different compositions. When layers are formed with yarns having different mechanical properties, modifying the ratio of yarns between the two layers makes it possible to modify the elastic modulus value between the two layers, while other parameters remain unchanged. Of course, it is possible to modify this parameter, as well as at least one other parameter selected from the winding pitch and the composition of the second resin 7.

[0060] In certain embodiments, at least one layer has one or more second wire-like elements 6 and a second resin 7, in addition to a sheet 8 passing around the central portion 2. The sheet 8 may be a cloth or a woven element, strip, or braid. The cloth has wefts 8b and warp threads 8a. The woven element differs from the cloth in that it has no weft threads. There are oriented quasi-wefts like the wefts of the cloth, but they are mechanically different. The quasi-wefts do not join up.

[0061] It is particularly advantageous to use sheet 8, specifically sheet 8 having thread or wire-like elements oriented parallel to the first direction AA. When preform 1 is used to form an inlay-core type prosthetic element, the thread or wire-like elements oriented to the first direction AA enhance the transmission of forces according to the height of the prosthetic element, i.e., in the direction connecting the root apex to the tip of the crown portion. The thread or wire-like elements improve the mechanical strength and toughness characteristics in the presence of masticatory forces. These benefits are observed with forces in the first direction AA, or with an angular offset equal to 45°.

[0062] In this particular case, it is advantageous to form a preform whose maximum dimension perpendicular to the first direction AA, for example, its diameter, is less than 40 mm. The configuration of the wire-like elements of the central portion 2 and the peripheral portion 3, and possibly the diameter of the preform, may be selected according to the tooth to be replaced, for example, its dimensions, its position in the mouth, and the characteristics of the adjacent teeth.

[0063] It is also possible to form larger dental preforms in a direction perpendicular to the first direction AA, and more preferably in the first direction AA. The preforms may have a diameter greater than 5 cm, preferably greater than 10 cm, and more preferably greater than 20 cm. The thickness in the first direction AA is preferably greater than 1 cm, more preferably greater than 2 cm, and more preferably greater than 3 cm. The dental preforms may then be used to form a prosthesis or even implant infrastructure to support bonded or coalesced teeth.

[0064] In the preferred method, sheet 8 is a cloth or woven element, whose weft or sub-weft threads are oriented primarily in a direction parallel to the first direction, and whose warp threads are positioned perpendicular to the first direction AA.

[0065] Sheet 8 is wider than the second wire-like element 6 in the first direction AA, preferably slightly wider than the second wire-like element 6, while remaining perfectly conforming to the winding pitch. Preferably, when several second wire-like elements are used in the same layer, sheet 8 extends slightly beyond the width occupied by the second wire-like element 6. The use of sheet 8 does not modify the winding characteristics.

[0066] In the preferred method, the sheet 8 is wrapped in the first direction AA, such that the ends of the wrapped sections overlap. The sheet 8 then forms a tube just around the central section 2 across the entire height of the dental preform 1.

[0067] One or more second wire-like elements 6 are placed between two consecutive sheets 8. The two windings of the two consecutive layers are separated by the sheet 8.

[0068] It is advantageous for sheet 8 to extend continuously across several consecutive layers. In other words, sheet 8 forms several coaxial tubes around the central portion 2. Connections between the tubes are made at the two ends of the preform in the first direction AA, alternating between the upper and lower ends, or the right and left sides. In certain embodiments, sheet 8 extends continuously across all layers of the peripheral portion 3.

[0069] Sheet 8 can be wrapped 360° several times around the central portion 2, for example, twice, five times, or more than ten times. The number of 360° wraps may be determined by the final diameter required for the dental preform.

[0070] Depending on the embodiment, when winding is performed, the sheets 8 are neatly stacked below or above at least one second wire-like element 6 in the layer.

[0071] As shown in Figure 6, when observed in a cross-sectional plane perpendicular to the first direction AA, sheet 8 appears to extend continuously across several layers and in a helical shape. The use of a sheet in a helical shape that extends across several layers, preferably all layers, allows for good force transmission between the outer and central portions of the preform. This configuration allows the preform to closely resemble the mechanical function of a natural tooth.

[0072] The wrapped configuration of the sheet and the second wire-like element 6 introduces a clamping effect, enabling the formation of a very strong wire-like element. The helical configuration also enhances the toughness of the dental preform, thereby facilitating the prevention of microcracks.

[0073] The helical configuration allows for the incorporation of long wire-like elements into small-sized preforms. The length of the wire-like elements, such as warp threads or second wire-like elements, may be at least 5 times the height of the preform, preferably at least 10 times the height, and may be at least 20 times the height. The length of the wire-like elements, such as warp threads or second wire-like elements, may be at least 5 times the diameter of the preform, preferably at least 10 times the diameter, and may be at least 20 times the diameter. The use of very long wire-like elements provides the preform with better mechanical strength.

[0074] The prepared dental preform may be a preform to be machined or a preform to be cut.

[0075] When a preform to be machined is fabricated without the preceding step of cutting perpendicular to a first direction, it is advantageous for the preform to be small in size, for example, having a diameter of less than 50 mm. The preform exhibits a volume similar to that of a tooth. A gripper 9 is fixed to the preform to facilitate machining as shown in Figure 1. Preferably, the machining of the preform defines the inlay core by a machining technique called CAD-CAM machining. Dental preforms can also form crown and root restorations. The preform is then covered with a crown, which can be made from ceramic or composite material, preferably zircon. Furthermore, it is possible to form implant abutments using dental preforms. The mechanical structure of the preform is particularly advantageous in that it can withstand multi-directional masticatory forces. It is also possible to form wider preforms, but this presents challenges in fabrication and in keeping the layers on top of each other. Wider preforms can, for example, form bridge infrastructure on natural teeth or implant teeth.

[0076] Once the preform to be cut is formed, it must be cut once or several times perpendicular to the first direction AA to define multiple base preforms that will form the preform to be cut. It is advantageous to form a preform that is taller than the first direction AA so that several preforms to be cut can be formed. It is also advantageous to form a wider preform for other uses other than inlay core formation, such as fitting the preform to a bridge infrastructure on a natural tooth or implant tooth. The cutting step allows for adjustment of the height of the preform according to requirements. It is preferable to form a tall preform to easily form a wider preform, which facilitates the bonding of second wire-like elements and sheets to each other in multiple layers.

[0077] Preforms are more deformable than equivalents made from metal and supports made from, for example, shape memory metal. The deformability of a preform is defined by the mechanical properties of its various layers. Preforms with large dimensional and modulus gradients allow the preform's properties to better match the stresses of the dental arch. Preforms can have a circular or elliptical cross-section, or a shape close to the latter, to better match the shape of the dental arch, thereby promoting a better match of mechanical properties.

[0078] The dental preform to be directly cut is cut to form an inlay-core type dental prosthesis with a root canal area and a crown area. The root canal area is designed to be inserted into, for example, the root canal of a laboratory model tooth. The crown area is designed to form the crown portion of a tooth destroyed by decay and to support, for example, a marginal prosthetic cap. The dental preform is cut so that the central portion sinks into the root canal of the tooth and extends into the crown portion. Part of the marginal portion is completely removed to form the root canal portion. The marginal portion is cut and partially left to form the crown portion, which will simulate the dentin of a natural tooth. The marginal portion is cut to define a shape close to the shape of the dentin to be replaced.

[0079] The dental preform 1 is milled using any suitable milling machine, preferably a computer-aided milling machine having, for example, three to five axes. The dental preform 1 is milled to reproduce a predetermined shape calculated from at least the imprint of the tooth to be treated.

[0080] Figures 2 and 3 show two embodiments in which the dental preform 1 has a gripper 9. In the embodiment of Figure 2, the gripper 9 is fixed to the outer wall of the marginal portion 3. In the embodiment of Figure 2, the gripper 9 is fixed to the end surface, i.e., the surface on which the first wire-like element 4 extends.

[0081] The formation of several coaxial layers with windings, preferably obtained by honeycomb winding, allows for more precise definition of the mechanical properties of the peripheral portion 3 of each layer, and thus enables modification of the characteristics according to the distance from the central portion 2.

[0082] This embodiment makes it possible to form a dental preform having substantially identical mechanical properties throughout the central portion depending on the radius value. Then, the expected technical properties can be defined according to the layer winding characteristics, including the composition of the resin used in the layer.

[0083] The dental preform 1 may be formed in various ways. The marginal portion 3 is formed on the mandrel 10. In one embodiment, the mandrel 10 is formed by a central portion 2, i.e., an assembly formed of a first wire-like element 4 and a first resin 5.

[0084] In another embodiment, the mandrel 10 is a different element, namely an element that does not form part of the dental preform 1, such as a metal mandrel. The marginal portion 3 is formed around the mandrel 10. The mandrel 10 is then removed to form a hole in the marginal portion 3. The hole is then filled with the first resin 5 and the first wire-like element 4 to form the previously defined central portion 2. This embodiment is particularly well suited for forming a preform to be cut.

[0085] The mandrel 10 extends in a first direction AA. In one embodiment, the mandrel 10 rotates around the first direction AA through which the mandrel 10 passes. In another embodiment, the second wire-like element 6 rotates around the mandrel 10.

[0086] The marginal portion 3 is formed around the mandrel 10, forming multiple layers on top of each other. In a cutting plane perpendicular to the first direction AA, the marginal portion 3 takes the shape of a ring around the central portion 2. The marginal portion 3 is formed by depositing one or more second wire-like elements 6 surrounding the mandrel 10 and depositing a second resin 7. The second resin 7 mechanically connects the second wire-like elements 6 to each other.

[0087] One or more second wire-like elements 6 define multiple layers arranged perpendicular to each other with respect to the first direction AA. The layers pass around the mandrel 10.

[0088] The second wire-like elements 6 are wound to define distinct layers of the marginal portion 3. Each layer of the second wire-like elements 6 exhibits a longitudinal direction offset from the first direction by an angle between 10° and 80°, or between 100° and 170°. The winding is performed with a constant angular offset from the first direction AA and from the direction perpendicular to the first direction AA. The second wire-like elements 6 are preferably wound from one end of the mandrel 10 to the other.

[0089] The formation of the marginal portion 3 is carried out such that two consecutive layers exhibit a second wire-like element 6 having opposite orientations. The second wire-like element 6 of the two consecutive layers defines a mesh when observed perpendicular to the first direction AA. Thus, if the winding of the second wire-like element in the first layer is carried out in an "upward" or "dextrous" direction, the winding of the immediately following and immediately following layers is carried out in a "downward" or "left-handed" direction, and vice versa.

[0090] When the edge portion 3 is formed, the second wire-like element 3 of each layer does not belong to the cloth or woven element.

[0091] To efficiently form the marginal portion 3, it is particularly advantageous to honeycomb wind one or more second wire-like elements 6 around the mandrel 10. In honeycomb winding, one or more second wire-like elements 6 are wound around the mandrel 10 in a continuous manner. One or more wire-like elements 6 are provided by an arm 11 that moves in one direction from a first fastener to a second fastener. Upon reaching the second fastener, the arm 11 moves in the other direction. The movement of the arm 11 is linked to the rotation of the mandrel 10 on itself or the rotation of the arm around the mandrel 10, but this second embodiment is less advantageous because it is more difficult to implement. Implementation of honeycomb winding is known by itself and has been used to form electrical inductance.

[0092] The honeycomb winding is particularly advantageous because it allows for the rapid and controlled formation of windings in each layer, and more specifically, in opposite directions between two consecutive layers. The position of the second wire-like element is determined by the position of the movable arm 11, and thus, when the winding pitch is constant between the two layers in the same direction, it is possible to arrange the wire-like elements on top of each other in a reproducible manner.

[0093] These winding modes allow for easy modification of the tension of the second wire-like element 6 when winding is performed. These embodiments also allow for easy modification of the relationship between the motion of the arm 11 and the rotation of the mandrel 10.

[0094] If the thickness of the second wire-like element 7 is known, then the thickness of the layer can be determined. If relevant, the thickness of the sheet 8 is also known. In order to modify the mechanical properties of the edge portion 3 according to its distance from the rotation axis of the mandrel 10 or the outer surface of the mandrel, it is possible to count the number of turns created and estimate the corresponding thickness.

[0095] The winding conditions are defined for each winding of the dental preform 1, and the dental preform 1 is formed by winding the second wire-like element 6 according to the winding conditions, that is, by imposing winding characteristics, composition of the second wire-like element 6, composition of the second resin 7, and, if applicable, composition of the impregnation resin.

[0096] Figure 5 shows a specific embodiment of the above configuration, comprising a mandrel 10 rotatably mounted around a first direction AA. Several second wire-like elements 6 are provided, passing through a spinneret 12 mounted on a movable arm 11. As the mandrel 10 rotates, the arm 11 and spinneret 12 move in a back-and-forth motion parallel to the first direction AA. The value of the motion of the arm 11 when the mandrel 10 rotates once defines the value of the angle between direction AA and the longitudinal axis of the second wire-like elements 6.

[0097] The second wire-like element 6 passes through an impregnation tank 13 containing an impregnation resin or a second resin 5. By modifying the composition of the resin in the impregnation tank 13, the composition of the resin can be modified according to the number of layers to be deposited, i.e., the number of turns of the mandrel 10 from the interface with the mandrel 10. This modification makes it possible to define the modulus gradient. In the preferred method, the impregnation tank provides the second resin 7. It is possible to adjust at least the impregnation rate of the second wire-like element, which makes it possible to define the thickness of the layers at least partially.

[0098] In the embodiment shown in Figure 5, three basic second wire-like elements are provided and joined together to form a single second wire-like element 6. By adjusting the number of basic wire-like elements that pass through the impregnation tank 13, the amount of second resin 7 deposited can be adjusted.

[0099] In an alternative embodiment, the arm 11 moves either the second wire-like element 6 or the impregnation tank 13 to move the second wire-like element 6 to form a winding.

[0100] In an alternative embodiment shown in Figure 7, each thread is associated with a specific impregnation tank 13.

[0101] Figure 7 shows an embodiment similar to the embodiment in Figure 5, in which four wire-like elements 6 are wrapped around the mandrel 10. For clarity in the figure, only two wire-like elements 6 pass through the spinneret 12 mounted on the movable arm 11. The movement of the arm 11 in the back-and-forth motion is linked to the rotation of the mandrel 10 as described above.

[0102] The two wire-like elements 6 pass through two different impregnation tanks 13, thereby allowing the resin associated with each of the wire-like elements 6 to be individually modified according to the number of turns of the mandrel 10 being performed.

[0103] Figure 7 also shows the winding of the sheet 8 around the mandrel 10. The sheet 8 and the second wire-like element 6 are wound in the same direction. The sheet 8 extends across the entire height of the dental preform 1, or beyond the height of the dental preform 1 to be formed, for example in the first direction AA, across the entire effective length of the mandrel 10.

[0104] The sheet 8 is wound either without a winding pitch in the first direction AA, or with a winding pitch that matches the overall height overlap of the dental preform 1 in each winding. In this embodiment, it is advantageous to use several second wire-like elements 6 distributed across the width of the sheet 8, preferably uniformly distributed across the width of the sheet 8. Each of the second wire-like elements 6 forms a winding around the central portion 2, and each winding extends in the first direction AA from one end to the other of the future dental preform 1. The windings are offset from each other in the first direction AA and may extend beyond the height of the preform 1.

[0105] When several second wire-like elements 6 are used in a certain layer, it is advantageous to associate a specific impregnation tank with each second wire-like element, thereby enabling the separation of the associated second resin composition and better controlling the changes in mechanical properties in the radial direction.

[0106] When several second wire-like elements 6 are used in a certain layer, it is advantageous to use an independent arm 11 for each second wire-like element 6 to separate the winding pitch, thereby better controlling the change in mechanical properties in the radial direction.

[0107] After the dental preform 1 has been completely rolled, if applicable, it is advantageous to carry out polymerization of the second resin 7 and the second impregnation resin.

[0108] In the preferred method, the wrapped and polymerized dental preform 1 exhibits a circular cross-section. The mechanical characteristics of the marginal portion 3 are modified according to the distance from the center of the dental preform 1, perpendicular to the first direction AA.

[0109] In certain embodiments, a dental preform 1 is provided, and a cutting step is then performed to define a plurality of basic preforms from the initial preform. The cutting plane ZZ is preferably perpendicular to a first direction AA. It is then possible to form basic preforms having heights (dimensions in the first direction AA) selected according to requirements.

[0110] Since dental preform 1 or the basic dental preform is designed to be milled to form dental prosthesis elements, the dimensions in the first direction AA are set to be between 10 mm and 60 mm, depending on the prosthetic element to be formed.

[0111] It is advantageous that the dental preform 1 has no wire-like elements that are primarily perpendicular to or extending perpendicularly with respect to the first direction AA and are common to the central portion 2 and the peripheral portion 3. The dental preform 4 has no wire-like elements passing through the first wire-like element 4 and being in between the windings of the second wire-like element 6.

[0112] It is advantageous that the dental preform 1 does not have any wire-like elements that extend perpendicular to the first direction AA and radially in the marginal portion 3.

[0113] It is advantageous that the preform does not have any wire-like elements that extend perpendicular to the first direction AA and radially in the central portion 2.

[0114] When a cutting or milling operation is performed perpendicular to the first direction AA, the end regions of the dental preform 1 are removed. End windings that connect one layer to a continuous layer extending outward or inward are removed. These mechanically connected regions between windings arise from the honeycomb winding. The removal of the end windings means that the windings are mechanically connected only by the second resin 7. Without this second resin 7, the windings would mechanically separate from each other.

[0115] In the preferred configuration, the dental preform 1 exists as a disc with a constant circular cross-section in a first direction from one end of the preform to the other. Alternatively, the cross-section may be a circle with a flat portion. Other shapes are conceivable with a constant cross-section in the first direction AA from one end of the dental preform 1 to the other. The dental preform is preferably designed to form a dental prosthesis for incorporation into a laboratory model.

Claims

1. A dental preform (1), a central portion (2) formed by a plurality of first wire-like elements (4) and a first resin (5), said first wire-like elements (4) extending mainly in a first direction (AA) and said first resin (5) mechanically connecting said first wire-like elements (4) to one another; a peripheral portion (3) in the form of a ring around said central portion (2) perpendicular to said first direction (AA), said peripheral portion (3) comprising second wire-like elements (6) and a second resin (7), said second resin (7) mechanically bonding said second wire-like elements (6) to one another, said first wire-like elements (4) and said second wire-like elements (6) being mechanically bonded to one another by at least said first resin (5) and said second resin (7); Equipped with the peripheral portion (3) comprises a plurality of layers arranged on top of each other perpendicular to the first direction (AA), the layers passing around the central portion (2); each layer having at least one turn formed by at least one of said second wire-like elements (6), said at least one second wire-like element (6) presenting a longitudinal direction offset with respect to said first direction (AA) by an angle comprised between 10° and 80° or between 100° and 170°; said second wire-like elements (6) of two successive layers exhibit opposite orientations, said second wire-like elements (6) of each layer do not belong to a fabric or woven element, At least some of the layers further comprise a sheet (8) selected from a fabric, a woven element, a strip, or a braid, the sheet (8) being located below or above the second wire-like element (6) of the layers; The sheet (8) extends in the first direction (AA) from one end of the dental preform (1) to the other end and extends across all of the layers, the sheet (8) takes the form of a spiral in a cutting plane perpendicular to the first direction (AA), and in an observation direction perpendicular to the first direction (AA), the thickness of the sheet (8) alternates with the thickness of the second wire-like element (6), and is oriented from the central portion (2) to one end of the peripheral portion (3).

2. 2. Dental preform (1) according to claim 1, wherein said central portion (2) comprises wire-like elements which, in terms of volume, are predominantly said first wire-like elements (4).

3. 3. Dental preform (1) according to claim 2, wherein said central portion (2) comprises only said first wire-like element (4) and said first resin (5).

4. 2. Dental preform (1) according to claim 1, wherein said peripheral portion (3) has an increasing elastic modulus gradient when moving away from said central portion (2) perpendicular to said first direction (AA).

5. 5. Dental preform (1) according to claim 4, wherein said peripheral portion (3) exhibits a content of second wire-like elements (6) that increases monotonically when moving away from said central portion (2) perpendicular to said first direction (AA) to form said elastic modulus gradient.

6. 5. The dental preform (1) according to claim 4, wherein particles are added to the second resin (7), and the peripheral portion (3) exhibits a ratio of the second wire-like element content to the particle content that increases in the radial direction when moving away from the central portion (2) perpendicular to the first direction (AA) to form the elastic modulus gradient.

7. 7. The dental preform (1) according to claim 6, wherein the ratio of the second wire-like element (6) content to the particle content increases in an inversely proportional manner with the distance from the central portion (2) to form the elastic modulus gradient.

8. 2. Dental preform (1) according to claim 1, wherein a plurality of coaxial tubes are formed by the sheet (8) of said plurality of layers from the interface with the central portion (2) to the outer wall of the peripheral portion (3).

9. 2. Dental preform (1) according to claim 1, wherein each layer comprises several second wire-like elements (6) wound around said central portion (2).

10. A method for manufacturing a dental preform (1), comprising the steps of: - providing a mandrel (10) extending in a first direction (AA); forming a peripheral portion (3) in the form of a ring around said mandrel (10) perpendicular to said first direction (AA), said peripheral portion (3) having a plurality of layers passing around said mandrel (10), said layers being arranged around one another perpendicular to said first direction (AA), each layer comprising at least one second wire-like element (6) and a second resin (7), said second resin (7) mechanically bonding said second wire-like elements (6) to one another in said peripheral portion (3); Equipped with said at least one second wire-like element (6) of each layer presents a longitudinal direction offset with respect to said first direction (AA) by an angle comprised between 10° and 80° or between 100° and 170°; said at least one second wire-like element (6) of two successive layers exhibiting opposite orientations; said at least one second wire-like element (6) of each layer does not belong to a fabric or woven element, The mandrel (10) has a central portion (2) formed by a plurality of first wire-like elements (4) and a first resin (5), the first wire-like elements (4) extend mainly in the first direction (AA), the first resin (5) mechanically bonds the first wire-like elements (4) to one another, and the first wire-like elements (4) and the second wire-like elements (6) are bonded to one another by at least the first resin (5) and the second resin (7). or the mandrel (10) is removed to define an empty area in the peripheral portion (3), the empty area being filled with a plurality of first wire-like elements (4) and a first resin (5), the first wire-like elements (4) extending mainly in the first direction (AA), the first wire-like elements (4) and the second wire-like elements (6) being bonded to each other by at least the first resin (5) and the second resin (7); At least some of the layers further comprise a sheet (8) selected from a fabric, a woven element, a strip, or a braid, the sheet (8) being located below or above the second wire-like element (6) of the layers; 1. A method according to claim 1, wherein said sheet (8) extends in said first direction (AA) from one end of said dental preform (1) to the other end and extends over all said layers, said sheet (8) having the shape of a spiral in a cutting plane perpendicular to said first direction (AA) and wherein in an observation direction perpendicular to said first direction (AA) the thickness of the sheet (8) alternates with the thickness of the second wire-like elements (6) and is oriented from said central portion (2) to one end of said peripheral portion (3).

11. 11. A method for manufacturing a dental preform (1) according to claim 10, wherein two successive layers share said at least one second wire-like element (6), and said winding is formed by honeycomb winding.

12. 12. A method for manufacturing a dental preform (1) according to claim 11, wherein said at least one second wire-like element (6) extends continuously over all said layers of said marginal portion (3).

13. 11. The method for manufacturing a dental preform (1) according to claim 10, wherein each layer (6) further comprises a sheet (8) formed by a fabric or woven element, the weft or quasi-weft threads of which extend in said first direction (AA).

14. 11. A method for manufacturing a dental preform (1) according to claim 10, comprising the step of cutting at least the assembly formed by said central portion and said marginal portion perpendicular to said first direction (AA) to define the dimensions of said dental preform (1) in said first direction (AA).

15. 1. A method of manufacturing a dental prosthesis, comprising: - providing a dental preform (1) according to any one of claims 1 to 9; - cutting the dental preform (1), in which a part of the marginal portion (3) is completely removed to reach the central portion (2) designed to form the root canal anchorage, and another part of the marginal portion (3) is partially removed to form the crown portion of the dental prosthesis according to a predetermined shape; A method comprising:

16. 16. The method for manufacturing a dental prosthesis according to claim 15, comprising the step of cutting the dental preform (1) perpendicular to the first direction (AA) to define the dimensions of the dental preform (1) in the first direction (AA) before cutting is performed.

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