Method for producing a printable object

Abstract

A method for producing a printable object (160) is disclosed, the method including the steps of jetting a printing material using a printing element (200) having a movable printing tip onto a support material (140), the support material including an initiator that is a free radical polymerization initiator suitable for promoting hardening of the printing material while not causing polymerization of the support material, and curing the jetted printing material using at least one light emitting source (150, 155) that provides light that causes polymerization of the printing material, the curing being performed simultaneously with the jetting of the printing material.

Description

[Technical field]

[0001] The present disclosure relates to the production of objects manufactured using additive manufacturing. [Background technology]

[0002] Modern technologies such as 3D printing should be utilized in the fabrication of tissue engineering scaffolds, implantable or orally delivered drug releasing dossier, soft and hard tissue replacement reconstructions. Among many other technologies, tissue engineering and additive manufacturing (AM) technologies have been tested in recent years for the fabrication of hard tissue reconstruction devices and tissue engineering scaffolds that are either biostable, biodegradable, or partially biodegradable until the indication for use. Some criteria for scaffolds include, for example, biocompatibility, adequate mechanical strength, biodegradability or biostability, and sufficient porosity. The biocompatibility of a scaffold can be defined as the absence of local and systemic toxic effects on the host tissue and the ability to support normal cellular activities, including molecular signaling systems. Furthermore, a hard tissue replacement device or a biostable scaffold should withstand the load of physiological functions in the long term. For implantable and dental constructs, requirements may include, for example, non-toxicity, non-allergenicity, antibacterial properties, sufficient strength, wear resistance, and surface texture (implants) and gloss (dental constructs). Summary of the Invention

[0003] The scope of protection sought for various embodiments of the invention is indicated by the independent claims. To the extent that there are exemplary embodiments and features described herein that are not included in the scope of the independent claims, they should be interpreted as examples useful for understanding the various embodiments of the invention.

[0004] According to a first aspect, there is a method for producing a printable object, the method comprising jetting a printing material onto a support material using a printing element having one or more print heads that are movable, the support material comprising an initiator that is a free radical polymerization initiator suitable for promoting the hardening of the printing material while not causing polymerization of the support material, the method comprising activating the support material and hardening the jetted printing material in a step of the printing process using at least one light emitting source that provides light that causes polymerization of the printing material and activation of the initiator in the support material. It is noted that the support material comprises an initiator additive, in other words an initiator, which can also be understood as an initiator system contained in the support material.

[0005] In an exemplary embodiment according to the first aspect, the method may include resin injection bio-printing using an extrusion 3D printer having an injection tip or printing surface platform that moves in xyz directions, where material for the object is simultaneously injected and cured in a layer-by-layer manner onto a biocompatible hydrogel support.

[0006] In an exemplary embodiment according to the first aspect, the amount of support material is increased, i.e. the printing wells containing support material are filled while the print head moves vertically (y direction) so that printing can occur within the support material.

[0007] In an exemplary embodiment according to the first aspect, the support material that fills the printing wells during the vertical movement of the print head is activated by UV radiation, microwaves, or heating of a tube before being poured into the wells of the support material.

[0008] In an exemplary embodiment according to the first aspect, a support material is present that is biocompatible and non-solid for support and for removing oxygen inhibition of free radical polymerization or frontal polymerization, and the printing material is jetted onto such a support material and polymerized in such a manner that the printing layers adhere to each other due to a polymerization reaction of the jetted material.

[0009] In an exemplary embodiment according to the first aspect, an additive is present in the support material consisting of a free radical polymerization or frontal polymerization initiator suitable for accelerating the hardening of the jettable material but not causing hardening of the support material.

[0010] In an exemplary embodiment according to the first aspect, the support material includes a protective gas to ensure that polymerization of the printing material occurs with the formation of an oxygen-inhibiting surface layer on the printed object. The protective gas may also be referred to as a protective gas.

[0011] In an exemplary embodiment according to the first aspect, the protective gas protects the formed free radicals against oxidation and thus extends the lifetime of the formed free radicals.

[0012] In an exemplary embodiment according to the first aspect, the protective gas is formed upon activation of an additive in the support material for free radical formation.

[0013] In an exemplary embodiment according to the first aspect, printing is performed in a surface layer of the support material where the amount of protective gas and polymerization-accelerating free radicals is greatest.

[0014] In exemplary embodiments according to the first aspect, the printing material has a lower density, the same density, or a higher density than the support material, and up to the difference in density (Δρ), the printing material is poured into or onto the surface of the support material to assist the effects of surface tension to support the printable material, taking into account the effects of surface energy and Archimedes' principle at the temperature of the support material.

[0015] In an exemplary embodiment according to the first aspect, the gel-like composition of the support material increases its surface energy and viscosity due to intermolecular forces between the liquid molecules and the gellant molecules, which increases support for the printable material.

[0016] Generally, the support material may be a gel or liquid that provides support through an increase in surface tension.

[0017] In an exemplary embodiment according to the first aspect, the radical polymerization initiator additive of the support material can be activated by light of the same or other wavelength as the polymerizable jetted material, by microwaves, or by an increase in temperature.

[0018] In an exemplary embodiment according to the first aspect, there are additives of colloidal particles, biologically active molecules, antimicrobial components, drugs, compounds, fillers, or cells in a support material that are transferred to the printable object.

[0019] In an exemplary embodiment according to the first aspect, the support material ensures instant hardening of the printable material with the aid of the initiator of the initiator system of the printable material, which allows the printable object to have a complex shape without having some support to the printing surface platform.

[0020] In an exemplary embodiment according to the first aspect, the method may be carried out, at least in part, using a robocasting 3D printer or polyjet printer having a chamber for printing material and a jetting tip that controls the viscosity of the printing material and the dispersion of optional fillers and other additives via temperature or ultrasound.

[0021] In an exemplary embodiment according to the first aspect, the method includes using a computer program to control the printing speed, the thickness of the printed layer, the viscosity of the printed material and the dispersion of the filler, the wavelength of the polymerization light, the power in the printing process, the rate at which the support material is filled with activated new support material, and the change in the support material during the printing process.

[0022] In exemplary embodiments according to the first aspect, the printable object is initially secured to the bottom or walls of the support material well by initial contact with the material to be printed. Additionally or alternatively, the printable object may be secured to the walls and / or bottom of the well during the printing process.

[0023] In an exemplary embodiment according to the first aspect, the method is carried out by a system comprising one or more light emitting units for activating an initiator in the support material to promote polymerization and to cause photoinitiated polymerization of the printed material, enabling photopolymerization during or after jetting of the printing material onto the support material to cause solidification of the printing material and adhesion of the jetted material layers to each other.

[0024] In exemplary embodiments according to the first aspect, optical radiation for initiation and propagation of polymerization is continuous or pulsed, of one or more wavelengths, and delivered from one or more directions.

[0025] In exemplary embodiments according to the first aspect, the support material is a non-solid material, a high viscosity liquid, or a gel, which may or may not have solid, semi-solid, molecular, ionic, or cellular additives that can adhere to the interior and / or surface of the printed object.

[0026] In an exemplary embodiment according to the first aspect, the support material protects the printed material from ambient oxygen whenever oxygen inhibition of polymerization is prone to occur.

[0027] In an exemplary embodiment according to the first aspect, the support material transfers biologically active compounds such as growth factors, antimicrobial compounds, drugs, bioactive fillers, cells, or printable sensors to the surface of an interior portion of the printable object.

[0028] In an exemplary embodiment according to the first aspect, the printed object includes smart sensors for pressure, temperature, pH, antibody, and other immune system monitoring formed from materials, compounds, and systems of the support material.

[0029] In an exemplary embodiment according to the first aspect, the support material and the printing material can be modified during the printing process to enable the printed object to have a layered structure with respect to the printed material, the compound, and the material transferred from the support material to the printed object.

[0030] According to a second aspect, there is a system comprising a robocasting device configured to perform the method according to the first aspect.

[0031] According to a third aspect there is a system comprising a polyjet printer apparatus that is a means for carrying out the method according to the first aspect. [Brief description of the drawings]

[0032] [Figure 1A] 1 shows a Robocasting system and support material. [Figure 1B] Shown is the formation of a protective gas in the support material, concentration of the support material at the foamed surface, and a mechanism for adding additional support material during vertical y-axis movement of the print head. [Diagram 2] 1 shows a support material containing an additive that is transferred to a printed object. [Diagram 3] 1 illustrates the fabrication of a printable object that can be used as an implant. [Figure 4] 1 illustrates the fabrication of a printable object that can be used as an implant. [Diagram 5] 1 shows a graph of an exemplary result of successful polymerization. [Figure 6] This shows the surface hardness of the printed object. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0033] The following embodiments are illustrative. Although the specification may refer to "an", "one", or "some" embodiments in several places in the text, this does not necessarily mean that each reference refers to the same embodiment, and does not mean that a particular feature applies to only one embodiment. Individual features of different embodiments may be combined to produce other embodiments.

[0034] One group of materials that have good physical properties and are used in additive manufacturing (AM) and bio-printing, which can also be understood as 3D printing, are resin-based materials and composites. These materials can also be processed by several types of AM techniques. However, for manufacturing objects with complex shapes and objects that require good biocompatibility, there are some limitations of AM techniques. Furthermore, for transferring biologically active substances to objects created by AM, there are limitations of current AM techniques.

[0035] Another group of materials that has a role in bioprinting of tissue engineering scaffolds, drug delivery vehicles, and cell encapsulation are hydrogels. Hydrogels are cross-linked hydrophilic polymer systems that are insoluble in water. They have physicochemical properties that make them suitable for a wide range of biomedical applications. Hydrogels are also used as biomaterials in soft tissue augmentation because their highly viscous nature resembles natural soft tissue. In addition, hydrogels can be loaded with biologically active substances and cells. However, their mechanical properties may be weak for hard tissue repair and replacement applications.

[0036] Several 3D printing techniques, devices, and resins are available that are used to manufacture tissue engineering scaffolds, implants, implantable or orally delivered drug-releasing dossiers, dental constructs, and even living cell constructs. For example, biostable thermosetting monomer systems that can be used for implants and dental restorations are based on mono- or polyfunctional acrylate or methacrylate monomers and filler composites, while biodegradable resin-based materials are preferred for tissue engineering scaffolds and drug-releasing dossiers. Examples of drugs that are released from the printed object are anti-inflammatory drugs and antibiotics. The monomers cure in polymerization by free radical polymerization, cationic polymerization, cationic photopolymerization, or front polymerization, but these polymerizations are reactions that are inhibited by oxygen, which can be understood as ambient oxygen for example. In order to obtain a complete cure, i.e. a degree of cure (DC), called the monomer conversion of the monomer from the inner part to the surface, oxygen should not be present in the curing process. The adverse effects of ambient oxygen can be prevented, for example, by using an oxygen protection barrier before the final curing of the object takes place. A high DC of the monomer can help achieve benefits such as good mechanical properties, good biocompatibility, and high surface gloss, where desired, such as in dental constructions. Other methods can also be used to prevent the inhibiting effect of oxygen on light curing. These are to cure the object in a vacuum chamber or in an oxygen-free atmosphere of an inert gas (nitrogen, carbon dioxide, argon, helium).

[0037] When using a liquid-based AM process in stereolithography to manufacture an object, i.e., a printable object, a photocurable resin can be cured in a layer-by-layer manner from a liquid bath. It may also be possible to jet the printing material in a gas, e.g., air, onto a solid surface and cure it with light of the desired wavelength and irradiation power in a layer-by-layer manner. With respect to the AM process, systems such as a polyjet printing system or a robocasting system, which is an extrusion printing system, can be used for the AM process. For example, a robocasting system can be similar to direct ink printing and other extrusion-based AM printing techniques used in AM processes, including bioprinting of cells. If there is no support material for the jettable material, which is the printing material, the printable object can be supported using other means, such as several support stubs, to obtain a solid surface. Depending on the rheological properties of the printing material, the distance between adjacent stubs can be determined. The stubs may be removed when the object is subsequently finalized. Furthermore, in some examples, the use of stubs may reduce the dimensional accuracy of the manufactured object. As another example, in polyjet 3D printing, a separate support material can be printed simultaneously with the printing material. In that case, the support material becomes an integral part of the printable object and needs to be removed later. After removal of the polyjet support material, the printed object has a sticky, polymerization inhibited, non-glossy, non-biocompatible surface due to the printing process occurring in ambient air.

[0038] An alternative method to printing materials in gas using several support stubs is to jet the printing material into the support material. The support material can be a liquid, colloid, gel, or semi-solid material. A system using this method can be used to deposit and cure a bioink of a mixture of cells, support matrix, and nutrients to generate tissue-like constructs, for example. The bioink can be printed into, for example, a poloxamer gel, which is a biocompatible gel that supports the printing bioink. However, when poloxamer gels and other gels are used as support materials for 3D printing with printing materials made of thermosetting monomers or composites in the robocasting technique, the gel can contaminate the surface of the printing layer, and therefore the printing layers may not adhere to each other upon polymerization, resulting in weak structures in the printable object. In addition, the movement of the printing tip of the robocasting system in the gel can also cause the gel itself to move, reducing the dimensional accuracy of the printable object. It is also possible that the printing pressure of the material from the printing tip spreads into the support gel before the start of polymerization.

[0039] It would therefore be beneficial to have a system and / or method for producing well-polymerized printable objects by thermoset robocasting extrusion jetting techniques that allow good adhesion between layers, eliminates the oxygen inhibition layer, provides immediate initiation of hardening of the jettable material and support of the jettable material for high precision printable objects. The possibility to add components, which can be understood as additives, such as cells, compounds, and fillers, to the printable object during the printing process via the support material may also be a desired property.

[0040] An exemplary embodiment of a robocasting device included in a robocasting system can be understood as a device that includes at least one print head having a chamber for the printing material, a jetting tip or printing surface platform configured to jet the printing material onto the support material where polymerization of the printing material occurs, and a computer control unit that controls the jetting parameters of pressure, temperature, and viscosity, the speed of the jetting tip or printing surface platform movement in xyz directions within the support material, a light emitting unit or microwave emitting device that polymerizes the printing material within the support material and activates an initiator system within the support material, and a heating-cooling unit and an ultrasonic emitting unit within the printing chamber, controls the amount of support material during the printing process, and adds or modifies the support material. Such a robocasting device can be utilized to print a variety of objects, such as objects that can be used for tissue engineering scaffolds, surgical implants for hard and soft tissue repair and replacement, and dental constructs. For example, in some embodiments, the robocasting apparatus has an ejection tip that has a length from the bottom of the chamber to its tip that is greater than the depth of the support material on which the object is to be printed, and may vary from about 1.50 mm to about 100.0 mm, although other lengths may be used depending, for example, on the object to be printed. Further, in some exemplary embodiments, the support material may be contained in a container such that the depth of the support material is determined based on the size of the object to be printed. For example, the depth of the support material may exceed the height of the object to be printed by about 1.0 mm or more.

[0041] FIG. 1A shows an exemplary embodiment of a system including a robocasting device, such as the robocasting device described above. The system can therefore be understood as a robocasting system. In this exemplary embodiment, there is a portion of the robocasting device called the printing element, which includes an ejection tip 130 configured to move in directions x, y, and z 105, and the movement can be controlled by a control unit, which is a computer control unit including computer instructions configured to control the movement. Furthermore, the printing element includes a chamber 170, which can include a printing material of a resin or resin composite. The viscosity of the printing material can be controlled by a thermoelectric element 120 of the chamber 170. The thermoelectric element can be included in the printing element, attached to the chamber 170, or adjacent to the chamber 170. That is, the thermoelectric element 120 controls the viscosity of the printing material. The dispersion of the filler of the resin or resin composite can be controlled by ultrasonic waves from the ultrasonic unit 110. The jetting tip 130, which moves through the support material 140, may be made of polished steel and may be optionally coated with a material such as polytetrafluoroethylene (Teflon) to reduce the friction of the tip on the support material during the printing movement. The jetting tip 130 further includes a light shield 190, which in this exemplary embodiment prevents direct curing light transmission of the upper light source that cures the printing resin at the tip of the jetting tip 130. This prevents the jetting tip from clogging due to the curing of the printing resin. The light shield 190 may be vertically adjustable to control the shadow area, i.e., the distance from the jetting tip where the jettable resin starts to polymerize. Thus, in general, the light shield 190 is positioned on the jetting tip 130 such that the printing material at the tip of the jetting tip 130 is prevented from curing. The support material may be contained in any suitable container so that the printing tip can print the printing material onto the support material. The support material contained in the container can be understood as a support material well 180. It should be noted that the container may also be referred to as a printing well. The walls of the wells are translucent and not UV protected for transmission of the curing light.The inner diameter of the ejection tip may be between 0.01 and 10.0 mm, such as 0.20 mm for a dimethacrylate resin composite. For example, the length 1002 of the ejection tip from the bottom of the chamber to the tip may be, for example, 1.50 mm to 100.0 mm, and may be 1.0 mm greater than the depth 1004 of the support material. The depth 1004 of the support material may be, for example, at least 1.0 mm greater than the height 1006 of the object to be printed.

[0042] The printing material may be a biodegradable or biostable resin or resin composite consisting of one of several functional reactive groups, including polymerizable monomers or comonomer systems, with compounds that allow addition or condensation polymerization of the resin or resin composite: free radical polymerization, ionic polymerization, ring-opening polymerization, or frontal polymerization. After polymerization, the resin may be any type of thermoplastic, thermosetting, copolymer, blend, or interpenetrating polymer network (IPN). If the printing material is a resin composite with particulate or discontinuous fiber filler, the filler is smaller than the inner diameter of the jetting tip.

[0043] The printing material contained within the chamber 170 is ejected through the ejection tip 130 into the bottom of the support material well 180 and is then cured with light by one or more light emission sources 150 located on the ejection tip 130 and / or the sides or bottom of the support material well 180. The side or bottom light emission sources are used to activate initiators to form free radicals in the support material. The wavelengths of emission of the light emission sources may differ from one another. The polymerization light may be emitted by the light emission sources 150 continuously or in a pulsed manner at the beginning, during, or after the printing process.

[0044] The support material, which does not polymerize itself, may be a Newtonian or non-Newtonian fluid or gel or viscous liquid that supports the jettable material jetted using the jetting tip 130 until the printing material is initiated by the curing light generated by one or more light sources 150, for example by microwave or front polymerization mechanism. If the jetting tip head is to be kept free of curing light radiation, i.e., head clogging is to be eliminated, the light shield is adjusted to the correct height from the central axis 132 of the jetting tip section to the distance of the upper light source. Clogging of the jetting tip can be prevented by, for example, adding ethanol-methylhydroquinone ( C 7 H 8 O 2) It can also be prevented by dipping the jetting tip in a mixture of inhibitors and allowing the ethanol to evaporate, leaving a coating of inhibitor on the surface of the jetting tip. If the support material is, for example, non-ionic polyacrylamide (PAM) ((C3H5NO) nIn the case of a gel of polyacrylamide gelatin (PAH) or methylcellulose-water hydrogel (MEH), these have the advantage of allowing the printed layers to adhere to each other and eliminating or preventing the formation of an oxygen-inhibiting layer on the surface of the printed object 160. In PAH, the water is bonded between the crosslinked polymer PAM by hydrogel bonds. PAH is stable, non-toxic, non-allergenic, non-absorbable, and non-biodegradable, and is therefore particularly suitable for use as a support material for 3D printing of biomedical and dental constructs. Another hydrogel support material of methylcellulose-water hydrogel (MEH) is a biocompatible hydrogel, also suitable for 3D printing of bio- and medical devices. The support material may be a mixture containing a hydrogel and additives such as emulsion fluid vesicles, cellulose microfibrils, cellulose nanocrystals, potassium salts, chitosan, alginate, polyvinyl alcohol, starch, gelatin, proteins, or inorganic fillers. The density of the additive may be lower, the same, or higher than the density of the support material, which affects the distribution and vertical position of the additive in the support material. The support material may be mixed prior to use for uniform distribution of the filler, or the filler may be allowed to fall or move onto the surface of the support material. This allows for uniform or gradient placement of the filler in the printed object.

[0045] The movement of the jetting tip in the support material may cause some flow of the support material due to shear forces. This may cause inaccuracies in the printable object. Also, high jetting pressure of the printing material being jetted into the support material may cause the printing material to spread in the support material, again reducing the dimensional accuracy of the printable object. Therefore, it is desirable for the curing of the printing material from the surface or the entire material (front polymerization) to occur immediately after the printing material is released from the jetting tip into the support material. To ensure immediate curing of the printing material once it contacts the support material, the support material may include an initiator, which is a free radical polymerization initiator, to activate the reactive groups of the printing material. Initiators in the support material for methacrylate-based jettable resin materials are, for example, 2,2'-azobis(2-methylpropionamidine) dihydrochloride ([=NC(CH3)2C(=NH)NH2]2·2HCl) (azo [AZO] chloride), or 2,2'-azobis(2-methylbutyranonitrile), 2-hydroxy-1-(4-(2-hydroxyethoxy)phenyl)-2-methyl-1-propanone, monoacylphosphine oxide, biphenyl, phenyl ether ... Other water-soluble free radical polymerization initiators may be used, such as acylphosphine oxide, 1-hydroxy-cyclohexyl-phenyl ketone, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-1-butanone, 2-methyl-4'-(methylthio)-2-morpholinopropiophenone, 2,2-dimethoxy-2-phenylacetophenone, eosin-Y, erythrosine, riboflavin (B2), or camphorquinone.

[0046] The chemical reaction of 2,2'-azobis(2-methylpropionamidine) dihydrochloride to alkyl radicals by activation with UV radiation at 330-380 (absorption maximum 375 nm) nanometer wavelength induces nitrogen gas formation in the support hydrogel material. The nitrogen gas in the support material behaves as a protective gas against inhibition of free radical polymerization by oxygen diffusing into the hydrogel support material, protecting the free radicals from oxidation and extending their lifespan. In the printing process on support materials with living cells and tissues, there may be a source of local oxygen reservoir for the cells to survive within the support material until they are transferred to the printed object.

[0047] The biocompatibility of the initiator is related to the initiator compound, the concentration of the initiator, and the exposure to the curing light. Typically, curing light with UV wavelengths (350-390 nm) is used for 3D printing. When dental resin composites are cured by light, blue light wavelengths (460-470 nm) are used, which have less harmful effects on cells and tissues. Therefore, it is beneficial to use blue light instead of UV light in the curing process of jettable materials for biomedical and dental constructs. Also, to protect the cells in the printing material from the effects of UV radiation, activation of the support material is performed before the jetting of the printing material takes place. The live cells are protected by UV-protective fluid vesicles.

[0048] For the sake of clarity, it is noted that in this disclosure, when a PAM is used in a PAH, it is intended that the PAM has already cured and no further reaction of the PAH support material occurs. The intent of the initiator, such as AZO chloride, is to promote, accelerate, and support the free radical polymerization of the printing material when it comes into contact with the support material that supports the hydrogel material.

[0049] The concentration of PAM in water relative to PAH may be between 0.1 and 20.0% by weight, for example 3.0% by weight. The concentration of methylcellulose (MEH) in water may be between 0.1 and 30% by weight, for example 5.0% by weight. To improve and accelerate the rate of curing of the jettable methacrylate resin, the support material may further comprise an activator compound compatible with the initiator (AZO chloride) of the support material. An example of an activator is 2-(dimethylamino)ethyl acrylate (H2C=CHCO2CH2CH2N(CH3)2). The concentration of the initiator (AZO chloride) in the support material (PAH) may be between 0.2 and 8.0% by weight, for example 4.0% by weight. The support material may be a glycerol gel or a high viscosity monomer of bisphenol-A-glycidyl dimethacrylate (bisGMA), urethane dimethacrylate (UDMA), bisphenol-A-ethyl methacrylate (bisEMA), or any other monomer or comonomer system that is not polymerized by light from the light source 150 of the printing apparatus.

[0050] It is also possible to add additives such as biologically active compounds, drugs, and cells to the support material to be transferred to the printed object. Examples of biologically active materials are fluid vesicles, nano- or micrometer-scale bioceramic or bioactive glass particles, bone morphogenetic growth factors, peptides, and RGD. Also, pH-controlling compounds may be used as additives in the support material to optimize the pH to best suit cell and tissue regeneration and polymerization of the printed material. An example of a pH-controlling compound is a sol-gel bioactive glass that increases the pH by rapid dissolution and release of ions for ion exchange reactions. If the printable object is intended to release biologically active substances or cells into the tissue engineering environment or in situ tissue after printing is completed, the printable object is made of biodegradable polymers such as polyester, poly(lactic acid), poly(caprolactone), or poly(glycolide), their copolymers, IPNs, blends, or composites of these, or crosslinkable hydrogels. The polymers of the printable objects used for this type of application are porous, which ensures high permeability to nutrients, oxygen, and metabolites. Moreover, the support material is preferably a biodegradable and environmentally friendly hydrogel, either naturally based hydrogels such as polysaccharides (e.g., chitosan) and proteins (e.g., collagen) or synthetic materials such as poly(lactic acid) (PLA), poly(glycolic acid) (PGA), and polypropylene fumarate (PPF).

[0051] The printed object 160 in this exemplary embodiment is a tissue engineering scaffold or bone anchoring implant, such as a dental implant, a soft tissue replacement implant, a stent, or a dental restoration (filling, crown, fixed partial denture, removable denture, orthodontic appliance, bite splint, surgical guide, dental model). The printed object 160 may be any other object, such as a technical object that is printed into a support material.

[0052] FIG. 1B shows another exemplary embodiment, which is a variation of the exemplary embodiment shown in FIG. 1A. The printing apparatus itself is the same as the exemplary embodiment of FIG. 1B, but in this exemplary embodiment, a support material 1010 is added to the chamber during printing. For this purpose, there is an injection tube 1020 that allows the support material 1010 to be added to the bottom of the chamber during printing of the object 160. Additionally or alternatively, there may be another injection tube 1025 that allows the support material 1010 to be added to the top of the surface of the support material. In this exemplary embodiment, the support material 1010 is a hydrogel material with an AZO initiator that is activated with UV radiation provided by a light source 150, which is optionally located on the side and / or bottom of the material well. The radiation initiates a chemical reaction in which alkyl radicals are formed with the simultaneous formation of nitrogen (N2) gas. Nitrogen is a protective gas in the support material to eliminate the occurrence of free radical polymerization inhibition by oxygen of the printing material. The nitrogen gas bubbles are moving upwards and the foamy surface with the greatest amount of protective gas and highest concentration of alkyl radicals is present on the support material. Thus, there may be an upper layer within the support material that can be understood as foam layer 1015.

[0053] If additives are present in the support material, the upward flow of the nitrogen gas also moves the additives to the surface of the support material. When the printing material reaches the foamed layer of the support material, it polymerizes and solidifies instantly, at least from its surface. This solidification allows the material to be printed without the need for any solid support material below the printing layer. To keep the object being printed always inside the foamed layer, the amount of support material is increased by flowing more support material through the tube into the printing well. The tube is at least partially translucent, allowing additional UV activation of the new support material to occur before it flows out due to the end of the tube. It is noted that flowing more support material can be understood as providing additional support material. The increase in the amount of support material in the well, i.e. the increase in depth, is synchronized with the vertical movement of the print head to keep the printable material inside the foamed layer and on the surface layer of the support material if no foamed layer is present. The increase in the amount of support material can be made to the bottom of the well or to the surface of the support material. The increased support material may be UV or temperature activated without activation.

[0054] Once a predetermined stage of printing is reached, or the entire object is printed, a curing light of 400-480 nm wavelength initiates polymerization of the object before it is removed from the print well. The printed object is then washed in water and further processed. The printing process can be performed with sterile printing and support materials in a sterile printing apparatus to facilitate the production of sterile medical devices.

[0055] FIG. 2 shows an exemplary embodiment of a printable object 215 manufactured for a bone defect in a damaged long bone 260. The damaged long bone 260 can be scanned using computed tomography (CT). Based on the CT scan of the defect, a digital model of the object to be printed can be generated using computer software, and the digital model can be used as an input to a printing device to print the object based on the input received at the printing device. In this exemplary embodiment, the printing device is a robocasting printing device as described in FIG. 1 with a printing element 200 including a printing tip that can be controlled to move in a direction 205. The printable object is printed into a container including a support material 210, which in this exemplary embodiment is a biodegradable support material. In this exemplary embodiment, the printable object is printed onto a biodegradable chitosan scaffold including mesenchymal stem cells (MSCs) 270 after receiving input including printing instructions based on the CT scan. The support material also serves as a cell culture medium including the necessary components for the cells in this exemplary embodiment. The printing material 280 is, in this exemplary embodiment, a visible blue light polymerizable resin of poly(lactic acid) (PLA) or poly(caprolactone) (PCL) with polymerizable methacrylic groups. The MSCs are trapped in the spaces between the layers 290 of the printing material during printing of the printable object 215. After hardening, the scaffold with the cells can be further cultured or directly implanted into the defect site 220 to promote bone growth. Additional fixation plates can be used to stabilize the healing bone.

[0056] FIG. 3 shows an exemplary embodiment of printing a printable object into a support material. The printable object may be any object for which the method of printing the object into a support material and then immediately curing is suitable. For illustrative purposes only, in this exemplary embodiment, the printable object 315 is an anatomically formed one-piece implant based on a cone beam computer tomogram image and an stl file formed based on the computer tomogram image. In this exemplary embodiment, a robocasting system according to the exemplary embodiment of FIG. 1 is utilized, and thus there is a printing element 200 with a printing tip that can be controlled to move in a direction 205. The scanned anatomical structure of the tooth root to be extracted is converted into a 3D printable object, which in this exemplary embodiment is an implant 315. The surface of the printed object 315 has a topography of a printing layer 310 that enhances the attachment of the implant to the bone by increasing the surface area for bonding with the bone. After 3D printing the implant 315 and final curing with additional light source 250, the final printable object 315 extracted from the print well, the final object 320, is sterilized in autoclave, hot air, critical point carbon dioxide or hydrogen peroxide plasma and embedded in an extraction socket to which the object 330 is attached. Thus, in this exemplary embodiment, a robocasting system is utilized to obtain the print instructions using an stl file based on the source model 360, thereby obtaining the printable object 315 based on the source model 360.

[0057] It should be noted that in general, curing may be performed in multiple occasions, for example using an initial cure and a final cure. It should also be noted that there may be more curing stages and that only some or all of the light emitting sources may be used in each curing occasion. Thus, different combinations of light emitting sources may be used in different curing occasions.

[0058] In some exemplary embodiments, when the printable object is printed using a Robocasting system and the printing material is printed into a support material containing an initiator, initial stabilization of the printable object to the bottom of the printing well can be performed by a weaker curing light source, which may comprise one or more light sources disposed below the support material well. During printing, the printing material can be first polymerized with a top curing light source, which may be a light source disposed above the support material well. The irradiation power can be, for example, 100 mW / cm 2 The final curing of the printing material, and therefore the printable object, can be performed using all of the curing light sources, which in some exemplary embodiments may also include light sources located to the sides of the printing wells.

[0059] 4 shows another exemplary embodiment in which a Robocasting system according to the exemplary embodiment shown in FIG. 1 is utilized, thus presenting a printing element 400 moving in a direction 405. In this exemplary embodiment, a Robocasting system is utilized to obtain a printed object 440, which is an anatomically formed implant, based on a cone beam computed tomogram image and a formed STL, OBJ, PLY, IGES, or STEP file. The printing material is jetted onto a support material, which in this exemplary embodiment includes an additive, which is a bioactive particle 410, which may be bioactive glass, tricalcium phosphate, hydroxyl apatite, carbonate apatite, calcium carbonate, or a combination thereof, in this exemplary embodiment with a particle size of 0.01 to 1000 micrometers, with a volume fraction of 2 to 80% with respect to the support material. The resulting image is used as input to print the printable object 320, which in this exemplary embodiment is an implant as described above, with a surface of the printable object 420 having a topography of the printed layer 425 that enhances the attachment of the implant to the target environment, such as bone, by increasing the surface area for bone bonding and with the aid of bioactive particles 430 that bind to the printed material during polymerization. After 3D printing and final curing with an additional light emitting source 450, the final printable object, object 440, extracted from the support material well is sterilized with autoclave, hot air, critical point carbon dioxide, or hydrogen peroxide plasma and embedded in an extraction socket and attached to the target object 440.

[0060] FIG. 5 shows a graph of an exemplary result of good polymerization of the printed layers with each other when printing is performed in a polyacrylamide-water gel. The homogeneity of the printed material was measured as the surface microhardness (Vickers surface hardness number, VHN) of the ground and polished surface of the printed object printed horizontally or vertically in the support material. The small standard deviation demonstrates that the surface is well polymerized over the entire surface, including the interface of the printed layers. In FIG. 5, the x-axis 510 shows the measurement area, which may be a randomly selected measurement area, and the y-axis 520 shows the VHN.

[0061] 6 shows another graph of exemplary results, where the y-axis 620 shows VHN and the x-axis 610 shows the measurement area. The surface hardness of the printed dimethacrylate-based resin composite and the absence of an oxygen inhibition layer on the surface of the printable object when the printing material is polymerized in contact with a support material is shown in bar 1, compared to the surface hardness of the ground and polished interior of the object shown as bar 2.

[0062] Although the present invention has been described above with reference to the embodiments according to the accompanying drawings, it is clear that the present invention is not limited thereto and can be modified in several ways within the technical scope of the appended claims. Therefore, all words and expressions should be interpreted broadly and are intended to illustrate, not to limit, the embodiments. It will be obvious to those skilled in the art that the concept of the present invention can be implemented in various ways as technology advances. Moreover, it is obvious to those skilled in the art that the described embodiments can be combined with other embodiments in various ways, although not necessarily.

Claims

1. 1. A method for producing a printable object, comprising: jetting a printing material, using a printing element having a movable printing tip, onto a support material contained in a printing well, the support material being a liquid or gel and including a polymerization initiator; supplying additional support material to the print well during printing; curing the jetted printing material using at least one light emitting source that provides light to cause activation of the polymerization initiator; Including, The method, wherein the activated polymerization initiator initiates polymerization of the printing material, and the curing is initiated and carried out simultaneously with jetting of the printing material.

2. The method of claim 1 , wherein the activated polymerization initiator causes the formation of free radicals in the support material, and the free radicals activate reactive groups of the printing material.

3. The method of claim 1 or 2, wherein the support material comprises a first layer and a second layer, the method including jetting the printing material onto the first layer of the support material.

4. The method of claim 3 , wherein the first layer has a higher concentration of gas, a higher concentration of free radicals, and a higher surface energy than the second layer.

5. providing said support material onto a bottom or wall of said printing well and / or onto said support material; The method of claim 1 further comprising:

6. activating the additional support material in a tube before the additional support material enters the print well. The method of claim 1 further comprising:

7. 7. The method of claim 6, wherein activation of the additional support material is performed using UV light, or by using heat, or by using microwaves.

8. The method of claim 1 , wherein the support material is a mixture comprising a Newtonian or non-Newtonian fluid or gel or viscous liquid or hydrogel and an additive, and the support material is not cured by the light emitting source.

9. The method of claim 1 , wherein the jetting is performed in a layer-by-layer manner and the curing causes the jetted layers to adhere to one another by polymerization.

10. The method of claim 1 , wherein the curing comprises using multiple light emitting sources, the multiple light emitting sources providing light emission from two or more directions.

11. The method of claim 1 , wherein the printing material is a biodegradable or biostable resin or resin composite of one or more functional reactive groups that include a polymerizable monomer or comonomer system and has a compound that allows polymerization of the resin or resin composite.

12. 10. The method of claim 1, wherein the support material is a hydrogel having an azo initiator, and activation of the support material with UV light results in a chemical reaction in which radicals are formed with the concomitant formation of a protective gas.

13. The method of claim 1 , wherein the at least one light emitting source provides the polymerization light continuously during printing or in pulses at the beginning, during, and / or after printing.

14. The method of claim 1 , wherein the curing uses multiple light emitting sources, the multiple light emitting sources providing light radiation at multiple wavelengths.

15. 1. A system comprising a three-dimensional printing device, Means for carrying out the method of claim 1 A system comprising:

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