Patent Application
20230363916
The present invention relates to a three-dimensional shaped object formed of a ceramic material, a method for manufacturing the same, and a control program.
An artificial bone is a three-dimensional shaped object formed of a ceramic material. The artificial bone is charged in a missing portion of a bone caused by bone breaking or the like. The artificial bone formed of a bio-ceramic material has replaceability with a living bone, differently from the artificial bone formed of a metal material. In other words, the artificial bone using the bio-ceramic material can be fused and replaced with a natural bone by growth of a new bone after being charged in the missing portion of the bone in a living body.
Patent Literature 1 discloses the following. An artificial bone is formed by a powder lamination method using a powder bone material of a ceramic material such as calcium phosphate. Then, the artificial bone is immersed in an aqueous solution, and is subjected to depressurization processing. Thereby, a gas inside the artificial bone is replaced with an aqueous solution. The artificial bone is sequentially left still to cause hydration reaction to occur. Thus, a strength of the artificial bone is improved.
Patent Literature 1: Japanese Patent No. 4575295
Conventionally, a three-dimensional shaped object formed of a ceramic material needs to have an increased internal dense degree for the purpose of securing a strength or the like. However, in some cases, a low dense degree is preferable. In the case of an artificial bone as the three-dimensional shaped object, it is necessary to increase an internal dense degree in order to secure a strength of the artificial bone. However, a too high dense degree hinders growth of a new bone, thus resulting in that it takes time for the artificial bone to be fused with a living bone or to be replaced with the living bone. Meanwhile, a low dense degree of the artificial bone causes an insufficient strength for reinforcing the living bone.
In view of the above, a primary object of the present invention is to enable a three-dimensional shaped object to achieve both of a property in the case of a high dense degree and a property in the case of a low dense degree and to have a high strength.
A secondary object of the present invention is to enable an artificial bone to have at least one of fusibility and replaceability with a living bone and to have a high strength.
In order to achieve the above-described object, a three-dimensional shaped object according to the present invention includes: a dense portion formed on one side so as to be dense; and a porous portion formed on an opposite side so as to be porous, wherein the dense portion and the porous portion are formed by a reaction product of a ceramic material with a chelating agent. This three-dimensional shaped object may be an artificial bone.
A method according to the present invention is a method for manufacturing a three-dimensional shaped object, and includes:
A program according to the present invention is a control program for controlling a three-dimensional shaping apparatus, the control program causing a computer to execute:
The three-dimensional shaped object according to the present invention includes the dense portion having a high dense degree and the porous portion having a low dense degree, and for this reason, can achieve both of a property in the case of a high dense degree and a property in the case of a low dense degree. The porous portion is formed by the reaction product of the ceramic material with the chelating agent. Thus, even the porous portion can have a high strength.
The following describes an embodiment of the present invention with reference to the drawings. The same reference sign is allocated to the corresponding part in each of the drawings, and duplicate description is omitted.
The artificial bone 10 is charged in a missing portion 20a of the living bone 20 in a living body (human or animal).
The three-dimensional shaped object 10 has a dense portion 3 formed on one side (a right side in
The dense portion 3 and the porous portion 5 are each formed by a reaction product of a ceramic material with a chelating agent. In other words, the ceramic material is cured as a result of chelating reaction with the chelating agent, and becomes the above-described reaction product. More specifically, the chelating agent dissolves the ceramic material, and calcium ions are thereby generated, and are trapped by the chelating agent so that the cured reaction product is obtained. In other words, the chelating reaction and solidification of the dissolved ceramic material result in the reaction product. The chelating reaction means chemical reaction in which a bi- or higher dentate ligand forms a ring and is bonded to central metal. The chelating agent means a compound having a ligand (polydentate ligand) that forms the above-described reaction product.
The dense portion 3 is a region where a dense degree is equal to or higher than a first threshold value. The porous portion 5 is a region where a dense degree is lower than a second threshold value. A dense degree indicates a ratio (occupancy percentage) of a space occupied by the constituent material (the reaction product) in the three-dimensional shaped object 10. Accordingly, a dense degree is 100% in a region in which the constituent material is completely charged and that includes no cavities. The first threshold value may be a value (e.g., 80%) within a range equal to or higher than 70% and is equal to or lower than 90%. The second threshold value may be a value (e.g., 60%) within a range equal to or higher than 30% and is equal to or lower than 65%. An upper limit of a dense degree of the dense portion 3 may be 100%. A lower limit of a dense degree of the porous portion 5 may be a value (e.g., 20%) within a range equal to or higher than 10% and is equal to or lower than 20%.
The three-dimensional shaped object 10 may include an intermediate portion 7 formed by the reaction product of the ceramic material with the chelating agent so as to be located between the dense portion 3 and the porous portion 5. A dense degree of the intermediate portion 7 is higher than a dense degree of the porous portion 5, and is lower than a dense degree of the dense portion 3. The intermediate portion 7 is bonded directly to each of the dense portion 3 and the porous portion 5. In one example, the intermediate portion 7 has a dense degree that gradually decreases as a position is more shifted from a side of the dense portion 3 to a side of the porous portion 5 (e.g., from a boundary with the dense portion 3 to a boundary with the porous portion 5). In another example, the intermediate portion 7 has a dense degree that is uniform over the entirety of the intermediate portion 7. When the intermediate portion 7 is not provided, the dense portion 3 and the porous portion 5 are bonded directly to each other.
The entirety of the three-dimensional shaped object 10 may be formed mainly of the above-described reaction product. For example, a ratio of a weight of the reaction product constituting the three-dimensional shaped object 10 to a total weight of the three-dimensional shaped object 10 may be equal to or higher than 80% (or equal to or higher than 90%) and equal to or lower than 100%. When the three-dimensional shaped object 10 is an artificial bone, the artificial bone 10 may further include one or both of the below-described cells and growth factors as components different from the above-described reaction product.
The above-described ceramic material may be calcium phosphate. The calcium phosphate may be, for example, α-tricalcium phosphate (α-TCP), β-tricalcium phosphate (β-TCP), octacalcium phosphate (OCP), or carbonate apatite, but is not limited to the specific calcium phosphate.
The above-described chelating agent may be an organic compound having three or more phosphate groups or carboxyl groups per one molecule. This organic compound may be etidronic acid, phytic acid, or citric acid, but is not limited to these.
The artificial bone 10 is charged in the missing portion 20a of the living bone 20 so as to form a bone body 30 together with the living bone 20.
The artificial bone 10 includes an outer surface 10a that is an outer surface of the bone body 30 in the charged state, and an inner surface 10b that is located inside the bone body 30 in the charged state. The outer surface of the bone body 30 is a surface facing to an outside of the living body (to a side of the skin 2). The outer surface 10a (e.g., the entirety of the outer surface 10a) is formed by the dense portion 3, and the porous portion 5 forms the inner surface 10b (a portion that is included in the inner surface 10b and that does not belong to the dense portion 3). In the charged state, the inner surface 10b formed by the porous portion 5 is adjacent to (e.g., in contact with) an inner surface of the missing portion 20a. The inner surface of the missing portion 20a is formed by the living bone 20.
As the inner surface 10b formed by the dense portion 3, a plurality of inner surfaces 10b may exist so as to face in mutually different directions. In the example of
The number of inner surfaces 10b is not limited to this example, and varies depending on a shape of the missing portion 20a in which the artificial bone 10 is charged. The three-dimensional shaped object (artificial bone) 10 may have a rectangular parallelepiped shape, a prismatic shape, a solid cylindrical shape, a pyramidal shape, a conical shape, a truncated conical shape, a truncated pyramidal shape, or a thin-piece shape. In the case of the artificial bone 10 having the prismatic shape or the solid cylindrical shape, one end surface of the prismatic shape or the solid cylindrical shape may be the outer surface 10a. In the case of the artificial bone 10 having the pyramidal shape, the conical shape, the truncated conical shape, or the truncated pyramidal shape, a bottom surface of the shape may be the outer surface 10a. In the case of the artificial bone 10 having the thin-piece shape, the artificial bone 10 may be charged in the missing portion 20a penetrating a skull (e.g., a calvarium) in a thickness direction thereof. In this case, the artificial bone 10 includes, as the above-described outer surface 10a, one side surface facing in its thickness direction.
The artificial bone 10 may include one or both of cells and growth factors. The cells and the growth factors, which are described in more detail below, are provided to promote replacement of the artificial bone 10 with natural bone tissue.
At a step S1, data (hereinafter, also referred to simply as shape data) for a three-dimensional shape of the three-dimensional shaped object 10 to be manufactured are generated. When the three-dimensional shaped object 10 is an artificial bone, the shape data representing the three-dimensional shape of the artificial bone 10 to be charged in the missing portion 20a are generated at the step S1, based on data of the three-dimensional shape of the missing portion 20a of the living bone 20. The shape data may include data representing a three-dimensional region occupied by the dense portion 3 that is a one-side portion of the three-dimensional shaped object 10. The shape data may include data representing a three-dimensional region occupied by the porous portion 5 that is an opposite-side portion of the three-dimensional shaped object 10. The shape data may include data representing a three-dimensional region occupied by the intermediate portion 7 that is a portion between the dense portion 3 and the porous portion 5 in the three-dimensional shaped object 10.
The shape data may be generated by a person operating an input device (such as a keyboard or a mouse) of a computer. When the three-dimensional shaped object 10 is the artificial bone 10, for example, data of the three-dimensional shape of the missing portion 20a may be displayed on a display of the computer, and a person may operate the input device while viewing the displayed data so that the shape data are generated. The data of the three-dimensional shape of the missing portion 20a are three-dimensional shape data of a region including the missing portion 20a in the living bone 20, and may be acquired by a CT scan, for example. The data of the three-dimensional shape of the missing portion 20a and the shape data may be CAD data, for example.
At a step S2, shaping processing for manufacturing the three-dimensional shaped object 10 is performed by a powder lamination method, based on the shape data generated at the step S1. In other words, at the step S2, a three-dimensional shaping apparatus 100 (3D printer) described below forms and cures a layer made of a powder ceramic material, based on the shape data, performs the same processing on an upper surface of the cured layer, and repeats the same processing on an upper surface of the newly cured layer, thereby forming the three-dimensional shaped artificial bone 10 including a large number of the cured and integrated layers. The above-described shape data include a large number of slice data pieces corresponding to a large number of the respective layers.
The step S2 includes a step S21 that is a layer forming step, and a step S22 that is a curing liquid applying step. At the step S2, the three-dimensional shaping apparatus 100 manufactures the three-dimensional shaped object 101 by repeating the steps S21 and S22 in this order as follows.
At the step S21, the powder 102 is used to form a ceramic layer. For example, as illustrated in
In the example of
At the step S22, curing liquid (hereinafter, also referred to simply as curing liquid) that is liquid including the chelating agent is applied to a target region on the upper surface of the layer formed at the step S21. For example, the control device 115 controls the curing device 113, based on the above-described slice data piece corresponding to the one layer, Thereby, the curing device 113 applies the curing liquid to the target region in the layer as illustrated in
At the step S22, an application amount of the curing liquid is controlled. In other words, the following is performed on the assumption that the target region in the layer formed at the step S21 includes a one-side region that comes to constitute a one-side portion of the three-dimensional shaped object 10, and an opposite-side region that comes to constitute an opposite-side portion of the three-dimensional shaped object 10. Based on the shape data, an amount of the curing liquid applied to each unit area in the one-side region by the curing device 113 may be controlled so as to be larger than an amount of the curing liquid applied to each unit area in the opposite-side region by the curing device 113. As a result, the one-side region is cured so as to constitute the dense portion 3, and the opposite-side region is cured so as to form the porous portion 5.
Further, in such control of an application amount of the curing liquid, the following is performed on the assumption that the target region in the layer formed at the step S21 includes an intermediate region between the one-side region and the opposite-side region. An amount of the curing liquid applied to each unit area in the intermediate region by the curing device 113 may be controlled so as to be smaller than the amount of the curing liquid applied to each unit area in the one-side region by the curing device 113 and be larger than the amount of the curing liquid applied to each unit area in the opposite-side region by the curing device 113. As a result, the intermediate region is cured so as to constitute the intermediate portion 7.
In addition, in the control of an application amount of the curing liquid, the amount of the curing liquid applied to each unit area at a position in the intermediate region by the curing device 113 may be changed depending on the position in the intermediate region. For example, as a position in the intermediate region is more shifted from a side of the one-side region to a side of the opposite-side region, the amount of the curing liquid applied to a unit area at the position by the curing device 113 may be gradually reduced. As a result, the intermediate portion 7 is formed so as to have a dense degree that gradually decreases as a position is more shifted from a side of the dense portion 3 to a side of the porous portion 5.
The above-described control of an application amount of the curing liquid may be performed by the control device 115, based on position ranges of the one-side region, the opposite-side region, and the intermediate region expressed by the shape data (slice data pieces).
When the step S22 is ended, the control device 115 causes the ascending-descending bottom portion 111a to descend by a thickness corresponding to one layer. Then, the step S21 and step S22 are performed again. Repeating the step S21 and step S22 in this manner forms the three-dimensional shaped object (artificial bone) 10 of the reaction product of the ceramic material with the chelating agent. In other words, the three-dimensional shaped object 10 is formed by forming and curing all the layers corresponding to all the slice data pieces of the shape data. After all the layers are formed and cured in this manner, the processing proceeds to a step S3.
At the step S3, the three-dimensional shaped object 10 formed at the step S2 is taken out from the shaping container 111, and the entire three-dimensional shaped object 10 is washed with liquid (e.g., water). For example, a water flow is supplied to the three-dimensional shaped object 10 so as to remove, from the three-dimensional shaped object 10, the residual chelating agent that does not contribute to the chelating reaction, and other components included in the curing liquid (e.g., the below-described surface active agent).
Hereinafter, the shaping processing at the above-described step S2 is described in more detail.
The powder ceramic material 102 used at the above-described step S21 may be calcium phosphate. The calcium phosphate may be any one of α-tricalcium phosphate (α-TCP), β-tricalcium phosphate (β-TCP), octacalcium phosphate (OCP), and carbonate apatite.
The curing liquid used at the step S22 is liquid including at least the chelating agent. The curing liquid may be obtained by dissolving the chelating agent in water. The chelating agent is an organic compound having three or more phosphate groups or carboxyl groups per one molecule. This organic compound may be any of etidronic acid, phytic acid, and citric acid.
The curing liquid may include another substance in addition to the chelating agent. For example, the curing liquid may further include a surface active agent.
The three-dimensional shaping apparatus 100 may be one that uses an inkjet printer. In other words, the above-described curing device 113 of the three-dimensional shaping apparatus 100 may be a constituent element of the inkjet printer. In this case, the curing liquid is used as ink of the inkjet printer or instead of the ink. In this case, the curing device 113 is a movable carriage provided with a plurality of heads 113a for dropping or ejecting the curing liquid.
At the above-described step S22, the control device 115 controls the carriage 113 so as to be moved along the target region above the target region of the layer, and controls the heads 113a so as to drop or eject the curing liquid to respective positions in the target region. As a result, the curing liquid is applied to the entire target region in the layer.
In this case, in the control of an application amount of the curing liquid at the step S22, the control device 115 may control the application amount of the curing liquid by causing the number of the heads 113a used for applying the curing liquid to each unit area in the above-described one-side region to be larger than the number of the heads 113a used for applying the curing liquid to each unit area in the above-described opposite-side region.
In addition, similarly, for the above-described intermediate region, the control device 115 may control the application amount of the curing liquid by causing the number of the heads 113a used for applying the curing liquid to each unit area in the intermediate region to be smaller than the number of the heads 113a used for applying the curing liquid to each unit area in the above-described one-side region and to be larger than the number of the heads 113a used for applying the curing liquid to each unit area in the above-described opposite-side region. In this case, as a position in the intermediate region is more shifted from a side of the one-side region to a side of the opposite-side region, the control device 115 may gradually reduce the number of heads 113a used for applying the curing liquid to each unit area at the position. As a result, the intermediate portion 7 may be formed so as to have a dense degree that gradually decreases as a position is more shifted from a side of the dense portion 3 to a side of the porous portion 5.
In the case of the three-dimensional shaped object 10 as an artificial bone, for the purpose of promoting replacement of the artificial bone 10 with natural bone tissue of the living bone 20 after charging the artificial bone 10 in the living bone 20, one or both of cells and growth factors may be applied to the entirety or a predetermined portion of the target region in the layer at the step S22. The cells may be cells (e.g., osteoblasts and osteoclasts) existing in the bone tissue, may be stem cells before differentiation, or may be one or both thereof. The growth factors may be bone morphogenetic protein (BMP) having strong ability to induce bone regeneration, or may be a basic fibroblast growth factor (b-FGF), a transforming growth factor (TGFβ), an insulin-like growth factor (IGF-1), or the like as cytokine that promotes bone cell growth or matrix growth.
In the case where the cells are applied to the artificial bone 10, a cell inclusion liquid including the cells is prepared. For example, the cell inclusion liquid may be a liquid in which cells are dispersed. At the above-described step S22, the cell inclusion liquid is dropped or ejected to the entirety or a predetermined region of the target region of the layer from another head 113b provided in the above-described carriage 113. This predetermined region may be, for example, the opposite-side region that becomes the porous portion 5.
In the case where the growth factors as well as the cells are applied to the artificial bone 10, the growth factors may be included in the above-described cell inclusion liquid, or a growth factor inclusion liquid including the growth factors may be prepared in addition to the above-described cell inclusion liquid. In the latter case, at the above-described step S22, the growth factor inclusion liquid is dropped or ejected to the entirety or a predetermined region (e.g., the opposite-side region) of the target region of the layer from still another head (not illustrated) provided in the carriage 113. In the case where only the growth factors out of the cells and the growth factors are applied to the artificial bone 10, at the step S22, the growth factor inclusion liquid is dropped or ejected to the entirety or a predetermined region (e.g., the opposite-side region) of the target region of the layer from the head 113b provided in the carriage 113.
The above-described three-dimensional shaped object 10 includes the dense portion 3 having a high dense degree and the porous portion 5 having a low dense degree, and for this reason, can achieve both of a property in the case of the high dense degree and a property in the case of the low dense degree.
The porous portion 5 is formed by the reaction product of the ceramic material with the chelating agent. Thus, even the porous portion 5 can have a high strength. For example, in the case of the three-dimensional shaped object 10 as the artificial bone, the porous portion 5 can have a strength of 25 MPa to 30 MPa even when the dense degree is 60%.
In the case of the three-dimensional shaped object 10 as the artificial bone, the dense portion 3 having a strength higher than that of the porous portion 5 forms the outer surface of the bone body 30 in a charged state where the artificial bone 10 is charged in the missing portion 20a of the living bone 20 such that the artificial bone 10 and the living bone 20 form the bone body 30. Accordingly, the dense portion 3 can reliably protect the missing portion 20a (i.e., the artificial bone 10 charged in the missing portion 20a) against impact from an outside.
The inner surface 10b formed by the porous portion 5 is adjacent to (e.g., in contact with) the inner surface of the missing portion 20a of the living bone 20, in the above-described charged state. For this reason, new bone tissue (bone substance) easily enters the artificial bone 10 from the living bone 20 through the inner surface of the missing portion 20a. Thus, it is possible to implement the artificial bone 10 having high fusibility and replaceability with the living bone 20.
At the step S22 in the above-described shaping processing, the dense portion 3 and the porous portion 5 can be easily formed simply by changing an amount of the curing liquid applied to the layer of the powder 102. Further, the three-dimensional shaped object 10 is formed by the reaction product of the ceramic material with the chelating agent, and the reaction product itself has a high strength. Thus, it becomes unnecessary to perform firing treatment or the like for enhancing a strength.
The intermediate portion 7 may be provided between the dense portion 3 and the porous portion 5. In this case, the intermediate portion 7 has a dense degree that gradually decreases as a position is more shifted from a side of the dense portion 3 to a side of the porous portion 5. Thus, it is possible to enhance a strength of the three-dimensional shaped object 10.
A control program for performing the shaping processing at the above-described step S2 may be stored in the storage device 114, or may be stored in another storage device readable by a computer as the control device 115.
The control program causes the computer 115 to perform a layer forming processing. The layer forming processing causes the three-dimensional shaping apparatus 100 to form a ceramic layer, using the powder ceramic material 102. The layer forming processing is processing of causing the three-dimensional shaping apparatus 100 to perform the above-described step S21.
The control program causes the computer 115 to perform a curing liquid applying processing. The curing liquid applying processing causes the three-dimensional shaping apparatus 100 to apply, to the target region in the layer, the curing liquid including the chelating agent. The curing liquid applying processing is processing of causing the three-dimensional shaping apparatus 100 to perform the above-described step S22.
The control program causes the computer 115 to repeatedly perform the layer forming processing and the curing liquid applying processing. Thereby, the computer 115 causes the three-dimensional shaping apparatus 100 to repeatedly perform the step S21 and the step S22.
The above-described three-dimensional shaped object 10 may be an object other than the artificial bone. For example, the three-dimensional shaped object 10 may be a filter that collects particles in passing fluid.
The filter 10 may be, for example, an exhaust gas purification filter, an air cleaning filter, or a liquid filter. The exhaust gas purification filter is provided in an exhaust flow path of a heat engine such as an internal combustion engine or a boiler, and collects particles included in an exhaust gas from the heat engine. The air cleaning filter is provided in a flow path for circulating air in a room of a building, a vehicle, or the like, and collects particles in the circulating air. The liquid filter collects particles (foreign substances) in a liquid such as fuel or hydraulic oil.
In such a configuration, the fluid flows into the filter 10 from the porous portion 5, passes through the porous portion 5, subsequently passes through the intermediate portion 7, then passes through the dense portion 3, and flows out of the filter 10. In this process, particles in the fluid are collected by the filter 10. Among the particles in the fluid, the large particles are collected in the porous portion 5, the particles having an intermediate size are collected in the intermediate portion 7, and the small particles are collected in the dense portion 3.
After the filter 10 is used for a predetermined period of time, for example, pressurized water may be made to flow through the filter 10 from a side of the dense portion 3 to a side of the porous portion 5. Thereby, the particles accumulated in the filter 10 are removed, and the filter 10 may be used again.
Alternatively, the three-dimensional shaped object 10 may be a catalyst carrier. In this case, the catalyst carrier 10 may have the same configuration (configuration in
In the example of
In the case of the catalyst carrier 10, the dense portion 3 may have a solid cylindrical shape, the intermediate portion 7 may have a hollow cylindrical shape and be provided so as to surround an outer peripheral surface of the dense portion 3, and the porous portion 5 may have a hollow cylindrical shape and be provided so as to surround an outer peripheral surface of the intermediate portion 7. In this case, the fluid may flow into the dense portion 3 in an axial direction thereof, and then may pass through the intermediate portion 7 and the porous portion 5 in this order in a radial direction thereof.
The present invention is not limited to the above-described embodiment. As a matter of course, various modifications can be made within the scope of the technical idea of the present invention. For example, the three-dimensional shaped object 10 according to the embodiment of the present invention does not need to include all of a plurality of the above-described constituent elements, and may include only a part of a plurality of the above-described constituent elements.
2 skin, 3 dense portion, 5 porous portion, 7 intermediate portion, 10 three-dimensional shaped object (artificial bone), 10a outer surface, 10b inner surface, 20 living bone, 20a missing portion, 30 bone body, 100 three-dimensional shaping apparatus, 102 powder ceramic material (powder), 111 shaping container, 111a ascending-descending bottom portion, 112 powder introduction device, 112a powder container, 112a1 ascending-descending bottom portion, 112b roller, 113 curing device (carriage), 113a head, 113b head, 114 storage device, 115 control device (computer)
| Number | Date | Country | Kind |
|---|---|---|---|
| 2020-169561 | Oct 2020 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2021/031070 | 8/25/2021 | WO |
