A customized maxillofacial restoration and preparation method thereof

Abstract

The present invention relates to a customized maxillofacial prosthesis and a preparation method thereof, comprising the following steps: the patient undergoes a maxillofacial CT scan before surgery, obtains CT data and imports it into a digital surgical assistant software in DICOM format; the patient and the doctor discuss the surgical plan, separate the patient's peeling area in the digital surgical assistant software, and simulate and design the maxillofacial prosthesis, wherein the maxillofacial prosthesis has a regular porous structure for bone growth in the matrix at the bone connection site to obtain a 3D design model; after the 3D design model is repaired, it is imported into a three-dimensional printing software in the format of an STL file, the printing material is an implant-grade wire formed by mixing polyetheretherketone and bidirectional calcium phosphate, and the customized maxillofacial prosthesis is printed layer by layer through a nozzle melt extrusion, 3D printing is performed, and the support column is removed before the temperature is not less than 100° C. to obtain a customized maxillofacial prosthesis. The method is easy to implement, highly operable, and has an excellent application prospect.

Description

Technical Field

[0001] The present invention relates to cranio-maxillofacial bone repair technology, in particular to a customized maxillofacial prosthesis and a preparation method thereof. Background Art

[0002] Millions of craniofacial surgeries are performed worldwide every year for craniofacial bone replacement and augmentation. This brings a huge economic burden and patients' demands for appearance. Autologous and allogeneic grafts are the gold standard for the treatment of craniofacial defects; however, traditional manufacturing is limited to complex maxillofacial tortuosity, insufficient bone supply, and difficult to adapt to molding, which limits the replacement strategy.

[0003] Biomaterials have been widely used in the surgical field to replace scarce autologous or allogeneic bone sources, but there are many disadvantages in the processing through traditional molding techniques; mainly because of the poor commonality between implants and target user groups, one implant cannot be suitable for most audiences.

[0004] Additive manufacturing has gained considerable attention over the past decade because it can create implants tailored to the needs and characteristics of the patient. Biomaterial implants can improve the biocompatibility of implants, but they present new challenges due to stress shielding, radiopacity, high strength-to-weight ratio, and limited bone integration. For this reason, composite materials have been studied to overcome the limitations of traditional implants and improve their bone integration.

[0005] In the early days, metals such as silver and gold were considered the best candidates for craniofacial surgery, and in subsequent developments, titanium (Ti) was frequently used. Although metals have been successfully used for many years, metal implants do not meet all biomechanical requirements. In particular, stress shielding around implants is a common problem, which may occur at the interface between metal and bone and lead to surrounding bone loss. In addition, metal-based implants may corrode surrounding tissues and cause cytotoxic reactions by releasing metal ions into the host. In addition, because metal implants interfere with radiation from imaging, they affect three-dimensional image monitoring of the healing process and affect postoperative healing. In recent years, more and more attention has been paid to bioceramics, such as hydroxyapatite (HA) and tricalcium phosphate (TCP). These two materials have been extensively studied for skull repair, especially bidirectional calcium phosphate BCP, which is a mixture of the two in different proportions. Because they have excellent biological activity and chemical properties similar to natural human bones, they are gradually valued by the market.

[0006] However, the low mechanical strength and brittleness of large-area ceramics limit their use in bone repair. To overcome the limitations of bioceramics, they have been combined with other materials. In addition to the biocompatibility and mechanical strength of polyetheretherketone (PEEK), they have the advantage of being radiolucent over metal implants, which facilitates postoperative observation. Therefore, PEEK facilitates radiographic assessment of bioceramics fusion with natural bone (such as magnetic resonance imaging (MRI), computed tomography (CT), and X-ray scans), in contrast to the interference caused by metal implants.

[0007] Three-dimensional matching of the host's physiologically specific geometry is important for achieving both aesthetic and restorative mechanical function. Conventional manufacturing techniques such as injection molding, casting, and extrusion have been used to manufacture craniofacial implants; however, they are time-consuming and require repeated intraoperative modifications to produce patient-specific implants, the accuracy and precision of injection molded samples are also controlled by shrinkage, and complex porous structures cannot be machined. In the past decade, the use of additive manufacturing (AM) has received more attention, providing opportunities for the production of personalized implants.

[0008] For common 3D printing maxillofacial technologies, the most common one is FDM melt wire extrusion technology. As a layer-by-layer extrusion method, it also brings about the problem of low interlayer bonding strength, which leads to a decrease in mechanical properties, as well as the common problem of support removal, which limits the development of this field. In addition, when heating and extruding PEEK / BCP wire, although BCP increases the bone ingrowth performance of PEEK and also improves the mechanical properties of PEEK, it makes the melt-molded implant brittle and other problems. Summary of the invention

[0009] The purpose of the present invention is to overcome the shortcomings of the existing 3D printing maxillofacial technology and provide a customized maxillofacial prosthesis and a preparation method thereof, in order to form a craniomaxillofacial bone repair and reconstruction implant with high bone ingrowth.

[0010] The present invention uses a composite material composed of polymer PEEK and bidirectional calcium phosphate BCP, combined with 3D printing technology to develop patient-specific craniomaxillofacial implants. By matching the process conditions of the composite material and combining the use of support columns, the surface of the formed restoration is complete and smooth, which can achieve personalized and precise shaping of the patient, improve the matching degree with the surrounding tissues of the patient's defective part, and completely match the physiological curvature and size of the patient's maxillofacial face.

[0011] The prosthesis is designed with bone connection points on both sides, and adopts a porous structure to ensure that the implant will not slip or loosen after implantation, and maintain toughness to prevent damage, and can achieve the characteristics of close integration with surrounding bone tissue.

[0012] At the same time, the interior of the restoration is porous, with a volume filling rate of 80%-90%, which makes the restoration tough and has advantages during use, such as ensuring certain mechanical properties (elasticity) when locking screws.

[0013] The printing method adopted by the present invention not only ensures the curved structure of the restoration with the help of the support column, but also ensures that the support column is easy to remove without leaving any residue on the solid part of the restoration.

[0014] The specific plan is as follows:

[0015] A method for preparing a customized maxillofacial prosthesis comprises the following steps:

[0016] (1) The patients underwent maxillofacial CT scans before surgery, and the CT data were imported into digital surgical assistance software in DICOM format;

[0017] (2) The patient and the doctor discuss the surgical plan, separate the patient's peeling area in the digital surgical auxiliary software, and simulate and design the maxillofacial prosthesis, wherein the maxillofacial prosthesis has a regular porous structure hollowed out in the matrix at the bone connection site for bone ingrowth, and obtains a 3D design model;

[0018] (3) After the 3D design model is repaired, it is imported into the 3D printing software in the format of an STL file. The printing material is an implant-grade filament formed by a mixture of polyetheretherketone and bidirectional calcium phosphate. The customized maxillofacial restoration is printed layer by layer through melt extrusion by a nozzle. The setting parameters include: the printing nozzle temperature is 350°C-500°C, the printing hot atmosphere temperature is 20°C-250°C; the printing speed is 1600-1800mm / min, and the printing layer height is 0.05-0.08mm; 3D printing is performed, layer by layer from bottom to top, first printing the support column at the bottom, and then printing the maxillofacial restoration;

[0019] (4) Cooling down the temperature, removing the maxillofacial restoration from the support column before the printing hot atmosphere temperature is not less than 100° C., and taking it out after cooling to room temperature to obtain a customized maxillofacial restoration.

[0020] Further, the printing material is an implantable grade filament formed by mixing polyetheretherketone and bidirectional calcium phosphate with a diameter ranging from 1.70 to 1.80 mm, the printing nozzle temperature is 350° C. to 500° C., preferably 470° C. to 485° C.; the printing hot atmosphere temperature is 210° C. to 230° C.;

[0021] Optionally, during printing of the maxillofacial restoration, leakage control is performed, and the extruded wire is retracted in stages, i.e., the retraction speed is 1600-1800 mm / min, the nozzle is lifted 0.2-2 mm during retraction, 4-7 mm is retracted, and after retraction, 0.2-1 mm is extruded for compensation to ensure the smoothness and integrity of the upper surface.

[0022] Furthermore, the entire maxillofacial restoration is filled with a volume filling rate of 80%-90%, filled in a 0° / 90° grid format, the overlap rate between the shell and the filling is 30%-50%, and the filling extrusion line width is 85%-95%.

[0023] Furthermore, after the maxillofacial restoration is placed in contact with the base plate with the maximum contact surface, it is moved perpendicular to the base plate and away from the base plate at a distance greater than or equal to 5 mm, thereby generating the support column with a height greater than or equal to 1 mm.

[0024] Furthermore, the outer shell of the maxillofacial restoration is printed in 3-6 layers to ensure that there is enough space for processing the surface after peeling;

[0025] Optionally, the single-layer printing height of the maxillofacial restoration is 0.05-0.08 mm, and the surface roughness Ra is 22.28±15.26 μm.

[0026] Furthermore, the support column is printed in a single direction at 0°, with a bottom volume filling rate of 30%-45%, and support is generated at an overhang angle greater than or equal to 45°. The top surface volume filling rate of the support column is 80%-100% to ensure the integrity and smoothness of the lower surface of the maxillofacial restoration.

[0027] Furthermore, the height of the support column is 3-7 mm, preferably 4-5 mm.

[0028] Furthermore, the maxillofacial restoration is offset by 0.3-0.5 mm relative to the top surface of the support column.

[0029] The present invention also protects the maxillofacial restoration prepared by the method for preparing the customized maxillofacial restoration.

[0030] Furthermore, the maxillofacial prosthesis is a closed annular structure, and two opposite ends of the maxillofacial prosthesis are provided with bone connection sites for bone ingrowth, and the bone connection sites are regular porous structures, the depth of the holes is 1mm-3mm, and the size of the holes is 0.4-2mm.

[0031] Beneficial effects:

[0032] In the present invention, a peeling area is formed after scanning the patient, which is used to simulate the formation of a maxillofacial prosthesis. The maxillofacial prosthesis after 3D printing is highly fitted with the missing jaw. At the same time, the porous structure of the key part (bone connection) ensures the stability of the later prosthesis, which is conducive to cell adhesion and osteogenic differentiation, and promotes cell proliferation. When the bone tissue grows into the porous structure, it will not loosen or shift; it can ensure the comfort of patients with long-term implants, improve the recovery speed after surgery, and reduce the probability of complications.

[0033] Furthermore, in the present invention, by controlling the filling rate of the restoration, it can not only meet the strength requirements for use, but also reduce the weight of the restoration, thereby improving the patient's experience of use.

[0034] Furthermore, regular multiple pores are formed at the bone connection site of the restoration, which facilitates bone ingrowth at the bone connection site, has better integration with the human body, and strengthens the connection strength with the surrounding bones of the affected area.

[0035] Finally, the present invention forms an easily removable support column structure for personalized graphics by adjusting the filling rate and offset. Specifically, after the maxillofacial restoration is placed in contact with the base plate with the maximum contact surface, it is moved perpendicular to the base plate and at a distance greater than or equal to 5 mm away from the base plate to generate the support column with a height greater than or equal to 1 mm; by printing in a single direction at 0°, the bottom volume filling rate is 30%-45%, and support is generated at an overhang angle greater than or equal to 45°. The top surface volume filling rate of the support column is 80%-100%, so as to ensure the integrity and smoothness of the lower surface of the maxillofacial restoration, reduce the complexity of post-processing, and solve the problem of residual support.

[0036] In conclusion, the method for preparing the customized maxillofacial restoration of the present invention is easy to implement, highly operable, and has excellent application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the technical solution of the present invention, the accompanying drawings will be briefly introduced below. Obviously, the accompanying drawings in the following description only relate to some embodiments of the present invention, but are not intended to limit the present invention.

[0038] Figure 1 This is a schematic diagram of a flow chart provided by Embodiment 1 of the present invention;

[0039] Figure 2 is a schematic diagram of the structure of a maxillofacial prosthesis provided by an embodiment 1 of the present invention;

[0040] Figure 3 This is a schematic diagram of the positions of the maxillofacial restoration and the support column during the printing process provided in Example 1 of the present invention. DETAILED DESCRIPTION

[0041] The following are definitions of some terms used in the present invention. Other terms not mentioned here have definitions and meanings known in the art:

[0042] The invention provides a method for preparing a customized maxillofacial prosthesis, wherein the basic raw material is an implant-grade filament mixed with polyetheretherketone (PEEK) and bidirectional calcium phosphate (BCP) with a diameter range of 1.70-1.80 mm. The filament is melt-extruded through a nozzle and printed layer by layer to form a customized maxillofacial prosthesis with regular porous joints and porous interiors.

[0043] The printing nozzle temperature is 350℃-500℃, and the printing hot atmosphere temperature is 20℃-250℃.

[0044] The maxillofacial restoration needs to be leak-controlled, and the extruded wire is periodically retracted, i.e., the retraction speed is 1600-1800 mm / min, the nozzle is lifted 0.2-2 mm during retraction, and 4-7 mm is retracted. After retraction, 0.2-1 mm is extruded for compensation to ensure the smoothness and integrity of the upper surface.

[0045] The bone connection part of the maxillofacial prosthesis is provided with a regular porous structure for facilitating bone growth.

[0046] The bone connection part has multiple holes with a depth of 1mm-3mm and are square structures arranged regularly and perpendicular to the contact surface and parallel to the inside of the maxillofacial restoration, while ensuring that the remaining part can provide a fixing point for screws and bone plates.

[0047] The bone-setting part is porous and arranged in a matrix of square openings with a side length of 0.4-2 mm, and the spacing is greater than or equal to the side length.

[0048] The maxillofacial prosthesis is porous except for the bone connection part, and the rest of the part is adjusted to present a microporous structure by the filling rate. Due to the grid-like microstructural characteristics, specific stiffness and damping characteristics of the periodic porous structure, it can achieve the purpose of energy absorption when it is impacted. At the same time, when screws are used to fix the nail plate during surgery, the pores block the path of crack extension to achieve the purpose of energy absorption, so that the drilling of screws will not damage the overall structure, and interlayer cracking and overall damage are not likely to occur. At the same time, the maxillofacial sample is given the elasticity of the porous structure and the property of not being easily damaged by impact.

[0049] The entire maxillofacial prosthesis is filled with a filling rate of 80%-90%, filled in a 0° / 90° grid form, the overlap rate between the shell and the filling is 30%-50%, and the filling extrusion line width is 85%-95%. While ensuring the overall mechanical properties, a certain elasticity can be provided for the 3D printed prosthesis to prevent the delamination phenomenon caused by poor interlayer bonding common in FDM printing.

[0050] After the maxillofacial prosthesis is placed in contact with the base plate with the largest contact surface, it moves perpendicular to the base plate and at a distance greater than or equal to 5 mm away from the base plate to generate a square support column greater than or equal to 1 mm. At the same time, the number of shell circles is ensured to be 3-6 layers to ensure the processability of the surface. When the screw is drilled, the eye socket is perpendicular to the screw drilling direction in the Z axis (i.e., the interlayer bonding direction) to ensure the integrity of the prosthesis.

[0051] The support of the maxillofacial restoration is printed in a single direction at 0°, with a bottom filling rate of 30%-45%, and supports are generated at an overhang angle greater than or equal to 45°. The top surface filling rate of the support is 80%-100% to ensure the integrity and smoothness of the lower surface of the maxillofacial face.

[0052] The maxillofacial restoration sample is offset from the top surface of the support by 0.3-0.5mm to ensure that the bottom layer of the sample has a certain degree of peelability when in contact with the top surface of the support. When the wire falls and the offset distance is 0.3mm-0.5mm, a small temperature drop will be achieved in the air, which will help to make the peeling between the two layers more convenient, and will not damage the interlayer bonding of the sample surface and the integrity of the sample.

[0053] The printing speed of the maxillofacial restoration sample is 1600-1800 mm / min.

[0054] Its production and use methods are as follows: the patient undergoes a maxillofacial CT scan before surgery, and the CT data is imported into the digital surgical assistance software in DICOM format; after discussing the surgical plan with the doctor, the affected detachment area is separated in the software, and the maxillofacial restoration is simulated and designed, and a regular porous structure for bone growth is hollowed out in the matrix at the bone connection site; after the 3D design model is repaired, it is imported into the 3D printing software in the format of an stl file, and the support and printing parameters (filling rate, placement angle, layer height, etc.) are generated, and the sample is printed after completion.

[0055] Preferably, the nozzle temperature is 470°C-485°C;

[0056] Preferably, the printing speed is 1600-1800 mm / min, and the maximum speed does not exceed 1800 mm / min, otherwise the maxillofacial specimens will have missing threads, incomplete surfaces, etc.

[0057] Preferably, the layer height is 0.05-0.08 mm, which can ensure that the surface roughness Ra of the sample is 22.28±15.26 μm, which is conducive to cell attachment and bone ingrowth;

[0058] Preferably, the printing atmosphere temperature is 210° C.-230° C., and the printed model is maintained at a high temperature mainly through a circulating hot air system. After printing is completed, the printed restoration is taken out after the temperature of the printer chamber cools down to room temperature.

[0059] Preferably, the support height is 3-7mm. For complex and tortuous maxillofacial areas, use 1-2mm support columns, and for smooth maxillofacial areas, use 4-5mm support columns.

[0060] The preferred embodiments of the present invention will be described in more detail below. Although the preferred embodiments of the present invention are described below, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. In the examples, those without specifying specific techniques or conditions are carried out according to the techniques or conditions described in the literature in this area or according to the product specification. Those without specifying the manufacturer of reagents or instruments used are all conventional products that can be obtained commercially. In the following examples, if not clearly stated, "%" refers to volume percentage.

[0061] The equipment used below includes:

[0062] The 3D printing equipment is Apium M220 (Germany)

[0063] The main reagents used include:

[0064] Printing materials: Implant-grade filaments mixed with polyetheretherketone (PEEK) and biaxial calcium phosphate (BCP) with a diameter range of 1.73-1.80 mm, where the mass content of polyetheretherketone (PEEK) is 80% and the mass content of biaxial calcium phosphate (BCP) is 20%.

[0065] Example 1

[0066] A method for preparing a customized maxillofacial restoration, the process diagram is as follows Figure 1 As shown, the following steps are included:

[0067] (1) The patient underwent maxillofacial CT scan before surgery, and the CT data were imported into digital surgical auxiliary software in DICOM format, such as UG and Solidworks 3D design software;

[0068] (2) The patient and the doctor discuss the surgical plan, separate the patient's peeling area in the digital surgical assistance software, and simulate the design of the maxillofacial restoration to obtain a 3D design model.

[0069] like Figure 2 As shown, the maxillofacial prosthesis is a closed annular structure, including an upper surface 1, a lower surface 2 and a bone connection 3. It should be noted that the upper surface and the lower surface here are relative concepts. The maxillofacial prosthesis is flat O-shaped, and bone connection 3 for bone ingrowth is provided at two opposite ends in the transverse direction. The outer surface of the bone connection 3 has a matrix hollow structure, that is, a regular porous structure for bone ingrowth is provided.

[0070] (3) After the 3D design model is repaired, it is imported into the 3D printing software in the format of an STL file, and printed using printing materials. The customized maxillofacial restoration is printed layer by layer through melt extrusion by a nozzle: printing is performed layer by layer from bottom to top, first printing the bottom support column, then printing the contact surface between the support column and the lower surface of the restoration, and then printing the restoration. After printing is completed, when the temperature cools to not less than 100°C, the restoration can be peeled off, and the support column can be removed from the printer base.

[0071] Specifically, the wire diameter is 0.4mm, the extrusion ratio is 0.9, the printing temperature is 480℃, the ambient temperature is 220℃, the printing speed is 1600mm / min, and the layer height is 0.08mm. The retraction speed is 1600mm / min, the nozzle is lifted 2mm during retraction, 4mm is retracted, and 1mm is extruded after retraction.

[0072] There are multiple pores on the side of the restoration that contacts the surrounding bone, that is, the bone connection site is a square porous structure with a length and width of 0.6 mm, a matrix arrangement of 0.6 mm spacing, and a depth of 3 mm.

[0073] Maxillofacial restoration length: 58mm, width: 58mm. Internal filling rate 90%, filling angle 0° / 90°, internal filling pattern in grid form, shell and filling overlap rate 35%, filling extrusion line width 90%.

[0074] A solid support column is made along the outer contour of the lower surface 2 of the maxillofacial restoration. The minimum thickness of the support column is 5mm, the support column is 2mm high, the overhang angle is greater than 50°, it is automatically generated, the horizontal offset is 0.5mm, and the support column filling rate is 30%; the top surface of the support column is 3 layers of dense support layers with a filling rate of 80%. The printing material of the support column is the same as that of the maxillofacial restoration.

[0075] like Figure 3 As shown, a dense support column is automatically formed by printing and is located under the restoration, fully supporting the bottom of the restoration.

[0076] Example 2

[0077] A method for preparing a customized maxillofacial prosthesis comprises the following steps:

[0078] (1) The patient underwent maxillofacial CT scan before surgery, and the CT data were imported into digital surgical auxiliary software in DICOM format, such as UG and Solidworks 3D design software;

[0079] (2) The patient and the doctor discuss the surgical plan, separate the patient's peeling area in the digital surgical assistance software, and simulate the design of the maxillofacial restoration to obtain a 3D design model.

[0080] The maxillofacial prosthesis is a closed annular structure, including an upper surface 1, a lower surface 2 and a bone connection 3. It should be noted that the upper surface and the lower surface here are relative concepts. The maxillofacial prosthesis is flat O-shaped, and bone connection 3 for bone ingrowth is provided at two opposite ends in the transverse direction. The outer surface of the bone connection 3 has a matrix hollow structure, that is, a regular porous structure for bone ingrowth.

[0081] (3) After the 3D design model is repaired, it is imported into the 3D printing software in the format of an STL file, and printed using printing materials. The customized maxillofacial restoration is printed layer by layer through melt extrusion by a nozzle: printing is performed layer by layer from bottom to top, first printing the bottom support column, then printing the contact surface between the support column and the lower surface of the restoration, and then printing the restoration. After printing is completed, when the temperature cools to not less than 100°C, the restoration can be peeled off, and the support column can be removed from the printer base.

[0082] Specifically, the wire diameter is 0.45mm, the extrusion ratio is 0.85, the printing temperature is 470℃, the ambient temperature is 230℃, the printing speed is 1800mm / min, and the layer height is 0.05mm. The retraction speed is 1800mm / min, the nozzle is lifted 1mm during retraction, 7mm is retracted, and 0.5mm is extruded after retraction.

[0083] The bone connection site 3 is a square porous structure with a length and width of 0.4 mm, a matrix arrangement with a spacing of 0.4 mm, and a depth of 3 mm. There are multiple holes on the side of the restoration that contacts the surrounding bones.

[0084] Maxillofacial restoration length: 58mm, width: 58mm. Filling rate 80%, filling angle 0° / 90°, internal filling pattern is grid form. The overlap rate between shell and filling is 40%, and the filling extrusion line width is 85%.

[0085] Solid support is made along the outer contour of the lower surface 2 of the restoration, and the minimum thickness of the support column is 3mm. The support column is 4mm high, and the overhang angle is greater than 45° and automatically generated, with a horizontal offset of 0.5mm, and a filling rate of 30% inside the support column; the top surface of the support column is a dense support layer of 3 layers with a filling rate of 80%.

[0086] Example 3

[0087] A method for preparing a customized maxillofacial prosthesis comprises the following steps:

[0088] (1) The patient underwent maxillofacial CT scan before surgery, and the CT data were imported into digital surgical auxiliary software in DICOM format, such as UG and Solidworks 3D design software;

[0089] (2) The patient and the doctor discuss the surgical plan, separate the patient's peeling area in the digital surgical assistance software, and simulate the design of the maxillofacial restoration to obtain a 3D design model.

[0090] The maxillofacial prosthesis is a closed annular structure, including an upper surface 1, a lower surface 2 and a bone connection 3. It should be noted that the upper surface and the lower surface here are relative concepts. The maxillofacial prosthesis is flat O-shaped, and bone connection 3 for bone ingrowth is provided at two opposite ends in the transverse direction. The outer surface of the bone connection 3 has a matrix hollow structure, that is, a regular porous structure for bone ingrowth.

[0091] (3) After the 3D design model is repaired, it is imported into the 3D printing software in the format of an STL file, and printed using printing materials. The customized maxillofacial restoration is printed layer by layer through melt extrusion by a nozzle: printing is performed layer by layer from bottom to top, first printing the bottom support column, then printing the contact surface between the support column and the lower surface of the restoration, and then printing the restoration. After printing is completed, when the temperature cools to not less than 100°C, the restoration can be peeled off, and the support column can be removed from the printer base.

[0092] Among them, the wire diameter is 0.4mm, the extrusion ratio is 0.85, the printing temperature is 475℃, the atmosphere temperature is 220℃, the printing speed is 1600mm / min, and the layer height is 0.08mm. The retraction speed is 1600mm / min, the nozzle is lifted 2mm during retraction, 4mm is retracted, and 1mm is extruded after retraction. The square porous structure 3 at the bone connection is 0.5mm in length and width, arranged in a matrix with a spacing of 0.5mm, and a depth of 2mm. There are multiple holes on the side of the restoration that contacts the surrounding bones. The maxillofacial restoration is 58mm long and 58mm wide. The internal filling rate is 80%, the filling angle is 0° / 90°, the internal filling pattern is in grid form, the overlap rate between the shell and the filling is 50%, and the filling extrusion line width is 95%. Make a solid support along the outer contour of the bottom 2 of the restoration, and the thickness of the minimum support is 5mm. Support column 2mm, overhang angle greater than 45° automatically generated, horizontal offset 0.3mm, support filling rate 30%; top surface dense support layer 5 layers, filling rate 90%. After printing, remove the support before the temperature is not less than 100℃, which is the easiest to peel off as a whole.

[0093] Example 4

[0094] A method for preparing a customized maxillofacial prosthesis comprises the following steps:

[0095] (1) The patient underwent maxillofacial CT scan before surgery, and the CT data were imported into digital surgical auxiliary software in DICOM format, such as UG and Solidworks 3D design software;

[0096] (2) The patient and the doctor discuss the surgical plan, separate the patient's peeling area in the digital surgical assistance software, and simulate the design of the maxillofacial restoration to obtain a 3D design model.

[0097] The maxillofacial prosthesis is a closed annular structure, including an upper surface 1, a lower surface 2 and a bone connection 3. It should be noted that the upper surface and the lower surface here are relative concepts. The maxillofacial prosthesis is flat O-shaped, and bone connection 3 for bone ingrowth is provided at two opposite ends in the transverse direction. The outer surface of the bone connection 3 has a matrix hollow structure, that is, a regular porous structure for bone ingrowth.

[0098] (3) After the 3D design model is repaired, it is imported into the 3D printing software in the format of an STL file, and printed using printing materials. The customized maxillofacial restoration is printed layer by layer through melt extrusion by a nozzle: printing is performed layer by layer from bottom to top, first printing the bottom support column, then printing the contact surface between the support column and the lower surface of the restoration, and then printing the restoration. After printing is completed, when the temperature cools to not less than 100°C, the restoration can be peeled off, and the support column can be removed from the printer base.

[0099] Among them, the wire diameter is 0.48mm, the extrusion ratio is 0.9, the printing temperature is 470℃, the atmosphere temperature is 220℃, the printing speed is 1800mm / min, and the layer height is 0.05mm. The retraction speed is 1800mm / min, the nozzle is lifted 1mm during retraction, 5mm is retracted, and 0.5mm is extruded after retraction. The square porous structure 3 at the bone joint is 0.6mm long and wide, arranged in a matrix with a spacing of 0.6mm, and a depth of 3mm. There are multiple holes on the side of the restoration that contacts the surrounding bone. The maxillofacial restoration is 58mm long and 58mm wide. The internal filling rate is 80%, the filling angle is 0° / 90°, the internal filling pattern is in grid form, the overlap rate between the shell and the filling is 35%, and the filling extrusion line width is 80%. Make a solid support along the outer contour of the bottom 2 of the restoration, and the thickness of the minimum support is 5mm. The support column is 2mm high, the overhang angle is greater than 45° and is automatically generated, the horizontal offset is 0.4mm, and the support filling rate is 30%; the top surface has 5 dense support layers and the filling rate is 100%. After printing, remove the support before the temperature is not less than 100℃, which is the easiest to peel off as a whole.

[0100] Comparative Example 1

[0101] Referring to Example 1, the difference lies in the different settings of the printing parameters, specifically: wire diameter: 0.4mm, extrusion ratio: 0.9, printing temperature 480°C, atmosphere temperature 220°C, printing speed: 2000mm / min, layer height 0.1mm. The retraction speed is 1800mm / min, the nozzle is lifted 2mm during retraction, 4mm is retracted, and 1mm is extruded for compensation after retraction. The length and width of the square porous structure 3 at the bone connection are 0.6mm, arranged in a matrix with a spacing of 0.6mm, and the depth is 3mm. There are porous structures on the side of the restoration that contacts the surrounding bones. The maxillofacial restoration is 58mm long and 58mm wide. The internal filling rate is 90%, the filling angle is 0° / 90°, the internal filling pattern is in grid form, the overlap rate between the shell and the filling is 35%, and the filling extrusion line width is 90%. A solid support is made along the outer contour of the bottom 2 of the restoration, and the thickness of the support is 5mm at the minimum thickness. The support column is 2mm high, the overhang angle is greater than 50° and is automatically generated, the horizontal offset is 0.5mm, and the support column filling rate is 30%; the top surface has 3 dense support layers and the filling rate is 80%. After printing, remove the support before the temperature is not less than 100℃, which is the easiest to peel off as a whole.

[0102] In this comparative example, since the printing speed is greater than 1800mm / min, the thickness of each layer is increased accordingly, to 0.1mm, and the retraction speed is also increased to 1800mm / min. Although the time to print a sample is significantly reduced, the faster the speed, the lower the fineness of the sample. In addition, the increase in layer thickness causes the average surface roughness of the sample to be greater than 35μm.

[0103] Comparative Example 2

[0104] Referring to Example 2, the difference is that the printing parameter settings are different, specifically: wire diameter: 0.45mm, extrusion ratio: 0.85, printing temperature 470°C, atmosphere temperature 230°C, printing speed: 1800mm / min, layer height 0.05mm. There is no control for material leakage, no wire retraction, and no lifting of the nozzle during retraction. The length and width of the square porous structure 3 at the bone connection are 0.4mm, arranged in a matrix with a spacing of 0.4mm, and the depth is 3mm. There are multiple holes on the side of the restoration that contacts the surrounding bones. The length and width of the square porous structure 3 at the bone connection are 0.4mm, arranged in a matrix with a spacing of 0.4mm, and the depth is 3mm. There are multiple holes on the side of the restoration that contacts the surrounding bones. The maxillofacial restoration is 58mm long and 58mm wide. The filling rate is 80%, the filling angle is 0° / 90°, and the internal filling pattern is in the form of a grid. The overlap rate between the shell and the filling is 40%, and the filling extrusion line width is 85%. A solid support is made along the outer contour of the bottom 2 of the restoration, and the thickness of the support column is 3mm at the minimum thickness. The support column is 4mm high, the overhang angle is greater than 45° and is automatically generated, the horizontal offset is 0.5mm, and the support filling rate is 30%; the top surface has 3 dense support layers and the filling rate is 80%. After printing, remove the support before the temperature is not less than 100℃, which is the easiest to peel off as a whole.

[0105] In this comparative example, due to the lack of material leakage control, a large number of burrs were attached to the surface of the maxillofacial sample, resulting in a significant increase in roughness. In addition, it was necessary to deal with the burrs and other protrusions. At the same time, because the wire was not retracted during the printing process, the molten liquid remaining on the nozzle adhered to the pores around the porous structure 3 of the bone joint when the nozzle crossed the pores, and formed a blockage after cooling. The porous structure 3 of the bone joint was partially blocked.

[0106] The preferred embodiments of the present invention are described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, a variety of simple modifications can be made to the technical solution of the present invention, and these simple modifications all belong to the protection scope of the present invention.

[0107] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0108] In addition, various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. A method for preparing a customized maxillofacial prosthesis, characterized in that: The following steps are involved: (1) The patients underwent maxillofacial CT scans before surgery, and the CT data were imported into digital surgical assistance software in DICOM format; (2) The patient and the doctor discuss the surgical plan, separate the patient's peeling area in the digital surgical auxiliary software, and simulate and design the maxillofacial prosthesis, wherein the maxillofacial prosthesis has a regular porous structure hollowed out in the matrix at the bone connection site for bone ingrowth, and obtains a 3D design model; (3) After the 3D design model is repaired, it is imported into the 3D printing software in the format of an STL file. The printing material is an implant-grade filament formed by a mixture of polyetheretherketone and bidirectional calcium phosphate. The customized maxillofacial restoration is printed layer by layer through melt extrusion by a nozzle. The setting parameters include: the printing nozzle temperature is 350° C.-500° C., and the printing hot atmosphere temperature is 20° C.-250° C.; The printing speed is 1600-1800mm / min, and the printing layer height is 0.05-0.08mm; 3D printing is performed, layer by layer from bottom to top, first the support column at the bottom is printed, and then the maxillofacial restoration is printed; after the maxillofacial restoration is placed in contact with the base plate with the maximum contact surface, it is moved perpendicular to the base plate and away from the base plate at a distance greater than or equal to 5mm to generate the support column with a height greater than or equal to 1mm; the support column is printed at 0° in a single direction, the bottom volume filling rate is 30%-45%, and support is generated at an overhang angle greater than or equal to 45°, and the top surface volume filling rate of the support column is 80%-100% to ensure the integrity and smoothness of the lower surface of the maxillofacial restoration; (4) Cooling down the temperature, removing the maxillofacial restoration from the support column before the printing hot atmosphere temperature is not less than 100° C., and taking out the support and the base after cooling to room temperature to obtain a customized maxillofacial restoration.

2. The method for preparing a customized maxillofacial prosthesis according to claim 1, characterized in that: The printing material is an implant-grade filament formed by mixing polyetheretherketone and bidirectional calcium phosphate with a diameter ranging from 1.70 to 1.80 mm, the printing nozzle temperature is 350° C. to 500° C.; the printing hot atmosphere temperature is 210° C. to 230° C.

3. The method for preparing a customized maxillofacial prosthesis according to claim 2, characterized in that: The print head temperature is 470℃-485℃.

4. The method for preparing a customized maxillofacial prosthesis according to claim 2, characterized in that: The maxillofacial restoration is printed with material leakage control, and the extruded wire is retracted in stages, i.e., the retraction speed is 1600-1800 mm / min, the nozzle is lifted 0.2-2 mm during retraction, and retracted 4-7 mm, and then extruded again after retraction to compensate 0.2-1 mm to ensure the smoothness and integrity of the upper surface.

5. The method for preparing a customized maxillofacial prosthesis according to claim 1, characterized in that: The entire maxillofacial restoration is filled with a volume filling rate of 80%-90%, filled in a 0° / 90° grid form, the overlap rate between the shell and the filling is 30%-50%, and the filling extrusion line width is 85%-95%.

6. The method for preparing a customized maxillofacial prosthesis according to claim 1, characterized in that: The outer shell of the maxillofacial restoration is printed in 3-6 layers to ensure that there is enough space for surface processing after peeling.

7. The method for preparing a customized maxillofacial prosthesis according to claim 6, characterized in that: The single-layer printing height of the maxillofacial restoration is 0.05-0.08 mm, and the surface roughness Ra is 22.28±15.26 μm.

8. The method for preparing a customized maxillofacial prosthesis according to claim 1, characterized in that: The height of the support column is 3-7 mm.

9. The method for preparing a customized maxillofacial prosthesis according to claim 8, characterized in that: The height of the support column is 4-5 mm.

10. The method for preparing a customized maxillofacial prosthesis according to claim 1, characterized in that: The maxillofacial restoration is offset by 0.3-0.5 mm relative to the top surface of the support column.

11. A maxillofacial prosthesis prepared by the method for preparing a customized maxillofacial prosthesis according to any one of claims 1 to 10.

12. The customized maxillofacial prosthesis according to claim 11, characterized in that: The maxillofacial prosthesis is a closed annular structure, and two opposite ends of the maxillofacial prosthesis are provided with bone joining sites for bone ingrowth, and the bone joining sites are regular porous structures, the depth of the holes is 1mm-3mm, and the size of the holes is 0.4-2mm.

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