SYNTHETIC BLOCK INTENDED FOR FILLING IN A BONE DEFECT AND METHOD FOR MANUFACTURING SAME

Abstract

Disclosed is a synthetic block intended for filling in a bone defect. The block is made up of a part made of ceramic material which has a shape that enables same to fill in the bone defect, and which is capable of being stabilized once placed in the bone defect, a three-dimensional network of channels communicating with one another being formed at least partially in the part such as to allow through the fluids and cells that enable revascularization with a view to cell growth once the part is in place in the bone defect, the channels opening onto each surface of the bone defect in contact with the part once it is placed in the bone defect.

Claims

1-10. (canceled)

11. A synthetic block intended for filling in a bone defect at the surface of a bone, wherein the synthetic block is made up of a ceramic material part which has a shape allowing the synthetic block to fill in the bone defect and which is able to be stabilized when placed within the bone defect, a three-dimensional network of channels communicating with one another being at least partially formed within the ceramic material part for allowing through the fluids and cells that enable revascularization for cell growth once the ceramic material part is placed within the bone defect, the channels opening onto each surface of the bone defect in contact with the ceramic material part once the synthetic block is placed within the bone defect.

12. The synthetic block according to claim 11, wherein the ceramic material is one of a ceramic material which is at least partially resorbable and a non-resorbable ceramic material.

13. The synthetic block according to claim 11, wherein the ceramic material is selected among β-tricalcium phosphate (β-TCP), hydroxyapatite and mixtures thereof in any proportion.

14. The synthetic block according to claim 11, wherein the ceramic material is a mixture composed of, for 100 wt. %, 40-100 wt. % of hydroxyapatite and 0-60 wt. % of β-TCP.

15. The synthetic block according to claim 11, wherein the ceramic part externally has, integral therewith, at least one stabilization eyelet intended to abut against the surface of the bone to be restored, outside the bone defect, the stabilization eyelet being not provided with revascularization channels and being pierced with at least one hole for passing at least one stabilization screw.

16. The synthetic block according to claim 11, wherein the ceramic part is pierced with at least one through hole, from the surface intended to come into contact with the bone delimiting the bone defect to the free surface if one considers the position of the part placed within the bone defect, for passing at least one stabilization screw, the ceramic part being not provided with revascularization channels within the regions surrounding the through hole at least in the neighboring part of the free surface.

17. The synthetic block according to claim 11, wherein the ceramic part externally has, integral therewith, at least one stabilization eyelet intended to abut against the surface of the bone to be restored, outside the bone defect, the stabilization eyelet being not provided with revascularization channels and being pierced with at least one hole for passing at least one stabilization screw and wherein the ceramic part is pierced with at least one through hole, from the surface intended to come into contact with the bone delimiting the bone defect to the free surface if one considers the position of the part placed within the bone defect, for passing at least one stabilization screw, the ceramic part being not provided with revascularization channels within the regions surrounding the through hole at least in the neighbouring part of the free surface.

18. The synthetic block according to claim 11, wherein the part is not provided with revascularization channels within the region of its free surface if one considers the position of the part placed within the bone defect.

19. The synthetic block according to claim 11, wherein the revascularization channels have a variable section, are rectilinear or not, and open or not at the opposite side of the surface of the part intended to come into contact with the bone defect.

20. The synthetic block according to claim 11, wherein the channels forming the revascularization system have a square section which side is of 250-600 μm with a 200 μm tolerance.

21. The synthetic block according to claim 11, wherein the channels forming the revascularization system have a greater section within the region of the part intended to contact the bone delimiting the bone defect, the core channels of the part being square-section channels with a smaller side.

22. The synthetic block according to claim 11, wherein the channels are square-section channels with a 400-600 μm side with a 200 μm tolerance.

23. The synthetic block according to claim 11, wherein the density of the channels forming the revascularization system is higher within the one or more regions of the part intended to contact the bone defect.

24. The synthetic block according to claim 11, wherein the ceramic material constituting the part has an intergranular microporosity of 5-30% in volume, the micropores having a size of 0.1-10 μm.

25. A method for manufacturing a synthetic block as defined in claim 11, wherein the method comprises the following steps: acquiring a three-dimensional image of a patient's bone having the bone defect to be filled in; designing, by computer-aided design, a computing model of the synthetic block which shape corresponds to the bone defect, which has the revascularization channels and which sizes are slightly larger than the bone defect so as to take into account the shrinkage of the ceramic when manufacturing the synthetic block; changing this computing model of the synthetic block, by computer-aided design, to ensure the stabilization of the synthetic block within the bone defect; and manufacturing the desired synthetic block by stereolithography or 3D printing or technique of additive methods.

Description

[0058] To better illustrate the object of the present invention, several embodiments will be described below for indicative and non-limiting purposes, with reference to the attached drawings, in which:

[0059] FIG. 1 is a perspective schematic view of the healthy mandible of an adult human being;

[0060] FIG. 2 is a view of the body of the mandible of FIG. 1 comprising a bone defect;

[0061] FIG. 3 is a side schematic view of a block intended for filling in this bone defect, the block being consistent with a first embodiment of the invention;

[0062] FIG. 4 is a top schematic view of the block of FIG. 3;

[0063] FIG. 5 is a view corresponding to FIG. 2 after placing and stabilizing the synthetic block according to the first embodiment of the invention;

[0064] FIG. 6 is a view corresponding to FIG. 5 after resorbing the material of the synthetic block and replacing it with the patient's bone and placing artificial roots;

[0065] FIGS. 7 to 10 are front views of a maxilla respectively in a healthy state; after losing the incisive block; after placing a synthetic block according to the first embodiment of the present invention; and after complete bone healing and placing the dental implants;

[0066] FIGS. 11 and 12 are views corresponding respectively to FIGS. 3 and 4, showing a synthetic block performed according to a second embodiment of the present invention, the fixation screws used with this second embodiment being shown on FIGS. 11 and 12;

[0067] FIG. 13 is a cross-sectional view of the synthetic block according to the first or second embodiment in order to describe a possible structure;

[0068] FIG. 14 is a top view of a mandible part comprising a bone defect filled in with a synthetic block consistent with the second embodiment of the invention; and

[0069] FIG. 15 shows, on a larger scale, a longitudinal cross-sectional view of the synthetic block of FIG. 14, in order to describe the structure.

[0070] On the anatomic schematic views of the drawings, for clarity purposes, the soft tissues, such as gum, muscles and cheeks, and the vascular system are removed, while only the hard tissues, such as bones and teeth, remain.

[0071] If referring to FIG. 1, it can be noted that the mandible 1 of an adult human being is shown, with its body 2 and its two branches 3. The body 2 carries the teeth 4 of the lower dental arch, the teeth being embedded within the drilled sockets within the spongy alveolar edge of the mandible body. On the drawing, the teeth are not shown accurately, the purpose of the invention being to represent a synthetic block intended for filling in a bone defect and its positioning therein. The teeth discussed here have been numbered by their position with respect to the middle of the mandible, namely: 5, second premolar; 6, first molar; 7, second molar; 8, third molar or wisdom tooth.

[0072] On FIG. 2 is shown the mandible body after losing the teeth 6, 7 and 8 and the associated alveolar bone.

[0073] The bone defect 10 thus formed is trough-shaped extending from a side wall to the other of the mandible body.

[0074] The ceramic material part 11 intended to fill in this defect 10 is shown on FIGS. 3 and 4.

[0075] It comprises a body 12 which has a shape allowing it to perfectly fit the defect 10, and which externally bears three eyelets 13 in the example shown, namely two eyelets on one side and one eyelet on the other side.

[0076] The eyelets 13 are intended to abut against the respective side walls of the mandible as shown on FIG. 5. They each comprise a hole 14 for passing an osteosynthesis screw allowing to stabilize the part 11 when placed within the defect 10. The axis of the holes 14 is oriented so as to provide the desired orientation to the osteosynthesis screws in order to fix the eyelets 13 for a perfect stabilization of the part 11. Also, the eyelets 13 are positioned on the body 12 of the part 11 to ensure such stabilization.

[0077] On FIG. 6 is shown the mandible 1 after resorbing of the ceramic material of the part 11 and replacing it with the patient's bone. After healing, the positioning of dental implants 15 is made possible.

[0078] The structure of the part 11 will be described below in reference to FIG. 13.

[0079] FIGS. 7 to 10 correspond to the views 1,2,5 and 6, respectively, for a maxilla 16:

[0080] FIG. 7 shows a front view of the maxilla 16 bearing the teeth 17 of the upper dental arch;

[0081] FIG. 8 shows the corresponding front view with loss of the four incisors and bone loss, creating the bone defect 18;

[0082] FIG. 9 shows the ceramic material part 19 according to the invention which body 20 fills in the bone defect and the eyelets 22 abut against the front wall of the maxilla, allowing osteosynthesis screws to pass through the corresponding holes 22; and

[0083] FIG. 10 shows the front view of the maxilla after complete bone healing and placing the four dental implants on which the new teeth 24 have been placed.

[0084] FIGS. 11 and 12 are views corresponding to FIGS. 3 and 4, respectively, but with another embodiment of the means for stabilizing the part 11.

[0085] In this embodiment, through holes or bores 25 are pierced through the part 11 (two bores 25 in the example shown) for passing the osteosynthesis screw 26 (shown on FIGS. 11 and 12) to penetrate the patient's bone delimited by the bone defect 10. On the other side, each bore 25 flares along a chamfer part 27 for accommodating the corresponding screw head 28. The positioning and orientation of the axes of the screws 26 are selected to ensure a good stabilization of the part 11 for a successful revascularization.

[0086] If referring to FIG. 11, it can be noted that the part 11 can have two types of “porosity”, namely: [0087] a main part 11a in which the three-dimensional network of revascularization channels is composed of square-section channels, for example, with a 250-600 μm side+/−200 μm; and [0088] a surface part 11b which is not provided with a revascularization network, thus without channels (with only the microporosity) for a better resistance.

[0089] As indicated above, the part 11a could have a network more dense or with larger channel sections in its region in contact with the patient's bone for an acceleration of the revascularization.

[0090] FIGS. 14 and 15 show a part 11 consistent with the second embodiment, which has three different regions regarding its “porosity”: [0091] a core part 11A in which the three-dimensional network of revascularization channels is composed of square-section channels, for example, with a 250-350 μm side+/−200 μm; [0092] a part 11B intended to come into contact with the patient's bone, in which the three-dimensional network of vascularization channels is more dense or is composed of square-section channels with a section larger than the channels of the part 11A, for example, with a 400-600 μm side+/−200 μm; and [0093] a surface part 11C surrounding the bores 25, which is not provided with a revascularization network, thus without channels (with only the microporosity) for a better resistance.

[0094] The structure according to the invention can be obtained according to any manufacturing method, layer by layer of the ceramic material.

[0095] The rapid prototyping and, in particular, the stereolithography are examples of such methods. This method is known by the man skilled in the art and, for a detailed description, reference can be made to U.S. Pat. No. 5,496,682 and EP1472081 patents.

[0096] Briefly, in pasty stereolithography, a paste is prepared, having for example the following composition (% of the total mass):

TABLE-US-00001 ceramic 80 photocurable binder 11.51 photoinitiator 0.09 dispersant 1.1 plasticizer 7.3

[0097] Here, the ceramic is hydroxyapatite or β-TCP or a mixture thereof. The photocurable binder can be an acrylate resin, such as di-ethoxylated A-bisphenol dimethacrylate or 1,6-hexanediol diacrylate. The photoinitiator will be selected among the photoinitiators commonly used in polymerization of acrylates. In particular, it can be noted 2,2′-dimethoxy-2-penylacetophenone and 2-hydroxy-2-methyl-1-phenyl-propane-1-one. The dispersant is advantageously a phosphoric ester. As a plasticizer, one or more agents of the group constituted by the family of glycols (for example, polyethylene glycol), the family of phthalates (for example, dibutylphthalate) and glycerol can be selected.

[0098] In a pasty stereolithography apparatus, the paste is first spread on a platform to form a first layer with uniform thickness. This first layer is irradiated by laser scanning according to the pattern defined for the layer. The first paste layer is cured by photopolymerization of the paste, except in the areas corresponding to the channels, which are not irradiated by the laser. Then, a second paste layer is spread on the first cured layer. This second layer is irradiated by laser scanning according to the pattern defined for the layer. The second paste layer is then cured, by photopolymerization of the paste, except in the areas corresponding to the channels. These operations are repeated in order to form the next stages.

[0099] Each of the layers formed has a thickness of 25-100 μm, namely 50 μm; it is obvious that the number of layers depends on the part being manufactured.

[0100] After photopolymerization of the last layer, the green part thus formed is cleaned to remove the non-polymerized composition. The cleaned green part is subjected to a heat treatment (debinding) and then to a sintering.

[0101] It is obvious that the above-described embodiments are provided for indicative and non-limiting purposes, and that modifications can be made without departing from the scope of the present invention.