Degradable magnesium metal fixation pins for oral tissue fixation and methods of making the same

Abstract

A biodegradable magnesium metal fixation pin for oral tissue fixation and its preparation method are disclosed. The fixation pin includes a pin head and a pin body. The entire fixation pin is made of 99.9-99.99% high-purity magnesium substrate, with no alloying elements added and an impurity content ≤0.01%. The surface of the fixation pin is sequentially coated with an oxide film layer and a polydopamine / hydroxyapatite composite coating. The oxide film layer has a thickness of 5-15 μm and a porous structure with pore sizes of 1-5 μm. The oxide film layer is prepared by a micro-arc oxidation process. The polydopamine / hydroxyapatite composite coating has a thickness of 10-20 μm, wherein the mass fraction of hydroxyapatite is 30-50%. This biodegradable magnesium metal fixation pin for oral tissue fixation features a reasonable structural design, excellent mechanical properties, and controllable degradation behavior.

Description

Technical Field

[0001] This invention relates to the field of oral medicine technology, and in particular to a biodegradable magnesium metal fixation pin for fixing oral tissues and its preparation method. Background Technology

[0002] In oral implantology or maxillofacial soft tissue surgery, such as connective tissue grafting (FGG), guided bone regeneration (GBR), gingival flap repair, and oral mucosal transplantation, it is often necessary to implant autologous connective tissue or biomembranes (such as collagen membranes or polylactic acid membranes) into the soft tissue defect or surgical area to guide tissue regeneration, protect the wound, and promote healing. Currently, the primary method for fixing implanted membranes in clinical practice is suture fixation. However, this method has several drawbacks: First, the suturing procedure is time-consuming, requiring meticulous suturing within a small oral surgical area, demanding extremely high surgical skills from the surgeon. Uneven suture tension can easily lead to membrane displacement and curling, affecting the surgical outcome. Second, sutures are foreign bodies, which can easily trigger local inflammatory reactions postoperatively, increasing the risk of infection. This is especially true in areas of the oral cavity with rich blood supply but fragile tissues, where suture irritation can cause gingival redness, swelling, and bleeding, prolonging the healing period. Third, if the sutures are not made of biodegradable materials, a second surgery is required to remove them or the fixation pins, increasing patient suffering and medical costs. This process may also cause further injury to the patient and damage newly formed tissue, affecting the repair outcome. Fourth, for irregular wounds or large-area membrane coverage, suture fixation lacks stability, making it difficult to achieve a close fit between the membrane and soft tissue, and easily leading to complications such as membrane exposure and detachment.

[0003] To address these issues, existing technologies have attempted to replace traditional sutures or fixation devices made of biodegradable materials, such as polylactic acid (PLA) and polyglycolic acid (PEG) staples. However, these materials suffer from poor mechanical properties, blunt and brittle tips, weak penetration, and poor handling. Furthermore, there is a mismatch between degradation rates and tissue healing cycles—some materials degrade too quickly, failing to provide long-term stable fixation support; others degrade too slowly, potentially causing chronic inflammation if left in the body for extended periods. Additionally, the limited mechanical strength of polymeric materials makes them prone to breakage and deformation under the mechanical loads generated by oral chewing movements, leading to fixation failure.

[0004] Magnesium and magnesium alloys, as a novel biodegradable metallic material, possess excellent biocompatibility, biodegradability, and suitable mechanical strength. Their degradation product, magnesium ions, can participate in human metabolism without leaving toxic or harmful residues in the body. Furthermore, magnesium ions promote osteoblast proliferation and accelerate tissue healing, and have already seen initial applications in orthopedics and cardiology. However, applying magnesium metal materials to membrane fixation in oral soft tissue surgery still faces several technical challenges. First, the moist, weakly acidic environment (pH approximately 5.5-7.5) within the cavity makes it difficult to precisely control the degradation rate of magnesium metal products in this environment. Second, the surface of magnesium metal is easily oxidized, and existing products do not meet the corrosion resistance requirements of the oral environment and cannot satisfy compatibility with biomembranes and soft tissues. Third, they are not suitable for the characteristics of oral soft tissue surgery, nor can they accommodate fixation structures of different wound sizes and locations, failing to meet the requirements for fixation stability and ease of operation.

[0005] Therefore, in view of the shortcomings of existing technologies, this paper proposes a biodegradable magnesium metal fixation nail with controllable degradation rate, suitable mechanical properties, and excellent biocompatibility, which is suitable for oral soft tissue surgery or GBR membrane fixation and has important clinical application value. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of existing methods for fixing connective tissue or GBR membranes in oral soft tissue surgery, and to provide a biodegradable magnesium metal fixation pin for oral soft tissue surgery and its manufacturing process. This invention solves the problems of complex suture fixation procedures, easy inflammation, and the need for secondary removal, as well as the insufficient mechanical properties and mismatched degradation rates of existing biodegradable fixation devices. It achieves rapid, stable, and minimally invasive fixation of the implanted membrane, promotes tissue healing in the surgical area, and reduces the incidence of complications. This biodegradable magnesium metal fixation pin for oral tissue fixation features a reasonable structural design, excellent mechanical properties, and controllable degradation behavior.

[0007] The above-mentioned objectives of the present invention are achieved through the following technical measures.

[0008] A biodegradable magnesium metal fixation pin for fixing oral tissues is provided, comprising a pin head and a pin body. The fixation pin is made entirely of 99.9-99.99% high-purity magnesium substrate, with no alloying elements added and an impurity content of ≤0.01%. The surface of the fixing nail is sequentially coated with an oxide film layer and a polydopamine / hydroxyapatite composite coating.

[0009] Preferably, in the above-mentioned biodegradable magnesium metal fixation nail for fixing oral tissues, the oxide film layer has a thickness of 5-15 μm and the surface of the oxide film layer has a porous structure with a pore size of 1-5 μm.

[0010] Preferably, the oxide film layer of the above-mentioned biodegradable magnesium metal fixation nail for fixing oral tissues is prepared by a micro-arc oxidation process.

[0011] Preferably, in the above-mentioned biodegradable magnesium metal fixation pin for fixing oral tissues, the thickness of the polydopamine / hydroxyapatite composite coating is 10-20 μm, wherein the mass fraction of hydroxyapatite is 30-50%.

[0012] Preferably, the biodegradable magnesium metal fixation nail for fixing oral tissues described above has a flat head with a thickness of 0.5-1.0 mm, an anti-slip groove for matching a screwdriver on the upper surface of the nail head, and a planar structure on the lower surface; The nail body has a length of 3.0-6.0 mm, a diameter of 1.3-1.8 mm, a conical tip, and a blunt tip structure.

[0013] Preferably, the biodegradable magnesium metal fixation pins used for fixing oral tissues described above have spiral patterns on their surface, with a pitch of 0.3-0.5 mm and a spiral pattern depth of 0.1-0.2 mm.

[0014] Preferably, in the above-mentioned biodegradable magnesium metal fixation screw for fixing oral tissues, the screw head is round or elliptical, and when the screw head is round, the diameter is 2.0-5.0 mm; The anti-slip groove on the upper surface of the nail head is cross-shaped or hexagonal, and the groove depth is 0.1-0.2mm; The lower surface of the nail head is a smooth plane with a surface roughness Ra≤0.8μm; The blunt structure at the tip of the nail is hemispherical with a radius of 0.2-0.3 mm.

[0015] Another object of the present invention is to provide a method for preparing the above-mentioned biodegradable magnesium metal fixation pin, comprising the following steps: S1, ingredient preparation and smelting, specifically: Select high-purity magnesium raw materials with a purity of ≥99.99%, remove the surface oxide scale, and put them into a vacuum induction melting furnace. Under argon protection, melt at 650-700℃ for 20-40 minutes. After stirring evenly, hold at 630-650℃ for 15-25 minutes, pour into a mold, and cool to room temperature to obtain high-purity magnesium ingots. S2, forging and rolling, specifically: High-purity magnesium ingots are hot-forged at 300-400℃ with a deformation of 40-60%, and then cold-rolled at 280-320℃ with a deformation of 30-50% to obtain high-purity magnesium plates or bars. S3, machining, specifically: Magnesium alloy sheets or bars are machined to produce a fixed nail blank in which the nail head and nail body are integrally formed, and spiral patterns, blunt tips and anti-slip grooves are processed. S4, surface micro-arc oxidation treatment, specifically: The fixing nail blank is placed in a micro-arc oxidation electrolyte for micro-arc oxidation treatment, forming an oxide film layer on the nail surface. S5, preparation of the composite coating, specifically: The fixing pins that form the oxide film are immersed in a polydopamine solution to form a polydopamine film; then hydroxyapatite is deposited by electrophoretic deposition and sintered to form a polydopamine / hydroxyapatite composite coating. S6, Cleaning and Sterilization, specifically: The fixation nails are ultrasonically cleaned and sterilized by irradiation to obtain the finished product.

[0016] Preferably, the above-mentioned method for preparing the biodegradable magnesium metal fixation pin, The electrolyte is composed of sodium silicate, sodium phosphate and sodium hydroxide, and the solvent is deionized water. The concentration of sodium silicate in the electrolyte is 8-12 g / L, the concentration of sodium phosphate is 3-8 g / L and the concentration of sodium hydroxide is 1-3 g / L. The surface micro-arc oxidation process of S4 is as follows: The fixing nail blank is placed in the electrolyte, with the fixing nail blank as the anode and the stainless steel plate as the cathode. Micro-arc oxidation is carried out using a pulse power supply at a voltage of 300-400V and a current density of 10-20A / dm². The treatment time is 10-30min, and the electrolysis temperature is controlled below 35℃. After processing, remove the fixing nail, rinse it with deionized water, and let it air dry to form an oxide film on the nail surface. Dissolve 1-5 g of polydopamine in 100-200 mL of Tris-HCl buffer solution with pH=8.0-9.0, and stir until completely dissolved to prepare a polydopamine solution. Hydroxyapatite powder with a particle size of 30-60 nm was ultrasonically dispersed in deionized water at a concentration of 15-30 g / L, and 0.2-1.0 g / L of dispersant was added to prepare a hydroxyapatite suspension. The specific process for preparing the composite coating of S5 is as follows: The fixation nails treated with micro-arc oxidation are placed in a polydopamine solution and immersed in a constant temperature oven at 30-40℃ for 1-5 hours. After removal, they are rinsed with deionized water and air-dried naturally to form a polydopamine film on the nail surface. The fixing pins were placed in a hydroxyapatite suspension, and hydroxyapatite was deposited by electrophoretic deposition at a voltage of 10-20V and a deposition temperature of 20-30℃ for 5-10 minutes. After deposition, the fixing pins were placed in a muffle furnace, heated to 400-500℃, and held for 1.0-2.0 h for sintering. After cooling to room temperature, a polydopamine / hydroxyapatite composite coating with a thickness of 10-20 μm was obtained.

[0017] Preferably, the above-mentioned method for preparing the biodegradable magnesium metal fixation pin, The electrolyte contains 10 g / L sodium silicate, 5 g / L sodium phosphate, and 2 g / L sodium hydroxide. During the surface micro-arc oxidation process of S4, a pulse power supply was used to perform micro-arc oxidation under the conditions of 350V voltage and 15A / dm² current density for 15 minutes, and the electrolysis temperature was controlled below 30℃. Dissolve 1g of polydopamine in 100mL of Tris-HCl buffer solution with pH=8.5 and stir until completely dissolved to prepare a polydopamine solution. Hydroxyapatite powder with a particle size of 50 nm was ultrasonically dispersed in deionized water at a concentration of 20 g / L, and 0.5 g / L of dispersant was added to prepare a hydroxyapatite suspension. The specific process for preparing the composite coating of S5 is as follows: The fixation pins treated with micro-arc oxidation were placed in a polydopamine solution and immersed in a constant temperature oven at 37°C for 3 hours. After being removed, they were rinsed with deionized water and air-dried naturally to form a polydopamine film on the surface of the pins. The fixing pins were placed in a hydroxyapatite suspension, and hydroxyapatite was deposited for 8 minutes using electrophoretic deposition at a voltage of 15V and a deposition temperature of 25℃. After deposition, the fixing pins were placed in a muffle furnace, heated to 450℃, held for 1.5 hours, and sintered. After cooling to room temperature, a polydopamine / hydroxyapatite composite coating with a thickness of 15μm was obtained.

[0018] The present invention relates to a biodegradable magnesium metal fixation pin for oral tissue fixation and its preparation method. The fixation pin is made entirely of 99.9-99.99% high-purity magnesium substrate, with no alloying elements added and an impurity content of ≤0.01%. The surface of the fixation pin is sequentially coated with an oxide film layer and a polydopamine / hydroxyapatite composite coating.

[0019] Compared with the prior art, the present invention has the following advantages: The degradation rate is precisely controllable, matching the healing cycle of oral soft tissue: This invention uses 99.99% high-purity magnesium as the base material, free from alloy element interference. Combined with the synergistic effect of the micro-arc oxidation film layer and the polydopamine / hydroxyapatite composite coating, the degradation cycle of the fixation pin in the weakly acidic environment of the oral cavity can be precisely controlled to 1-4 weeks, which is highly matched with the healing cycle of oral soft tissue. In the early stage of healing (1-2 weeks), the fixation pin maintains sufficient mechanical strength to provide stable fixation support for the biofilm. In the later stage of healing (2-4 weeks), the fixation pin gradually degrades, and the degradation products are pure magnesium ions, which can completely participate in human metabolism without any alloy impurities remaining. After the tissue has completely healed, the fixation pin has basically degraded and can be removed without secondary surgery, avoiding damage to the new tissue caused by suture removal and reducing patient pain.

[0020] Suitable mechanical properties and strong fixation stability: The magnesium alloy substrate of this invention has excellent mechanical strength (tensile strength ≥200MPa, yield strength ≥150MPa), which is far higher than that of existing polymer fixation nails. It can effectively resist the mechanical load generated by oral chewing movements and avoid fixation nail breakage and deformation. The continuous spiral pattern on the surface of the nail can enhance the occlusal force with soft tissue. The nail head presses the biomembrane tightly, realizing the close fit between the membrane and soft tissue. The fixation stability is significantly better than suture fixation and can effectively prevent complications such as membrane displacement, curling, and detachment.

[0021] Superior biocompatibility and extremely low tissue irritation: The 99.99% high-purity magnesium substrate has extremely high purity, with no alloy impurities added. The degradation products are only magnesium ions and water, with no toxic or harmful residues. Moreover, magnesium ions can participate in normal human physiological metabolism and are non-irritating to oral soft tissues. The polydopamine / hydroxyapatite composite coating has excellent biocompatibility with human tissues, which can further reduce the corrosion rate in the early stage of high-purity magnesium degradation and reduce local inflammatory reactions. At the same time, the porous structure of the micro-arc oxidation film layer is conducive to cell adhesion and proliferation, promotes tissue healing in the surgical area, and shortens the healing period. The flat-head nail cap design avoids pressure protrusion on the submucosal tissue, further reducing the risk of tissue irritation and improving postoperative comfort.

[0022] Convenient operation, minimally invasive and safe, and comfortable postoperatively: This invention is equipped with a dedicated blunt drilling instrument. The procedure of drilling first and then hammering in the fixation nail reduces the difficulty of implantation and avoids excessive traction damage to soft tissues caused by direct implantation. The fixation nail has a flat-head design, which is suitable for submucosal implantation and avoids the nail head protruding and compressing surrounding tissues, improving postoperative patient comfort. The nail tip has a blunt structure, which, together with drilling, further avoids damage to blood vessels and nerves. The anti-slip groove on the nail head, in conjunction with the dedicated instrument, facilitates precise positioning and hammering, making the operation simple and quick, and significantly shortening the operation time. No sutures or suture membranes are required, reducing foreign body irritation, lowering the risk of infection, achieving minimally invasive fixation, and improving surgical safety.

[0023] Wide adaptability and high clinical application value: This invention provides fixation pins of various specifications, which can be adapted to oral soft tissue surgical wounds of different sizes and locations. It is suitable for various surgeries that require fixation of the implanted membrane, such as CGF surgery, gingival flap repair, and oral mucosal transplantation. It solves many drawbacks of existing fixation methods, can significantly improve surgical results, reduce the incidence of complications, and has broad prospects for clinical promotion and application. Attached Figure Description

[0024] The invention will be further described with reference to the accompanying drawings, but the contents of the drawings do not constitute any limitation on the invention.

[0025] Figure 1 This is a schematic diagram of a biodegradable magnesium metal fixation pin for fixing oral tissues according to the present invention.

[0026] exist Figure 1 Including: 100 nails Anti-slip groove 110 Nail body 200 Nail tip 210, spiral pattern 220. Detailed Implementation

[0027] The present invention will be further described in conjunction with the following embodiments.

[0028] Example 1 A biodegradable magnesium metal fixation pin for fixing oral tissues, such as Figure 1 As shown, it includes a nail head 100 and a nail body 200, which are fixedly connected. Preferably, the nail head 100 and the nail body 200 are integrally formed.

[0029] The fixation pin is made entirely of 99.9-99.99% high-purity magnesium substrate, with no added alloying elements and an impurity content of ≤0.01%. The 99.9-99.99% high-purity magnesium substrate has a purity of ≥99.9-99.99% and impurities of ≤0.1-0.01%, primarily consisting of Fe, Cu, Ni, and other substances that cannot be completely removed during smelting. The high-purity magnesium substrate, without the need for added alloying elements, possesses suitable biocompatibility and biodegradability. Its degradation products are pure magnesium ions, which are more easily absorbed by the body's metabolism, eliminating the risk of alloying impurity residues and avoiding potential local tissue irritation caused by alloying elements. This makes it more suitable for minimally invasive procedures implanted under the oral mucosa. Furthermore, the degradation rate of the high-purity magnesium can be precisely controlled through subsequent surface coating treatments, meeting the fixation requirements of the soft tissue healing cycle.

[0030] The surface of the fixing nail is sequentially coated with an oxide film layer and a polydopamine / hydroxyapatite composite coating.

[0031] The oxide film has a thickness of 5-15 μm and a porous structure with pore sizes of 1-5 μm. It is prepared using a micro-arc oxidation process. The oxide film formed by micro-arc oxidation significantly improves the corrosion resistance of the magnesium alloy substrate, slows its degradation rate in the oral cavity environment, and its porous structure facilitates the adhesion of subsequent composite coatings. Furthermore, it promotes the slow release of magnesium ions, thus contributing to tissue healing.

[0032] The polydopamine / hydroxyapatite composite coating has a thickness of 10-20 μm, with hydroxyapatite comprising 30-50% by mass. High-purity magnesium, through oxide film and surface coating treatment, allows for precise control of degradation rate, meeting the fixed requirements of soft tissue healing cycles.

[0033] This biodegradable magnesium metal fixation pin for fixing oral tissues has a pin head 100 that can be either flat-headed or round-shielded. In this embodiment, the pin head 100 is flat-headed with a thickness of 0.5-1.0 mm. The upper surface of the pin head 100 has an anti-slip groove 110 for matching a screwdriver, and the lower surface is planar. Preferably, the lower surface of the pin head 100 is a smooth plane with a surface roughness Ra ≤ 0.8 μm.

[0034] The anti-slip groove 110 on the upper surface of the nail head 100 is a cross-shaped groove with a depth of 0.1-0.2mm. It should be noted that the anti-slip groove 110 on the upper surface of the nail head 100 is not limited to the cross shape in this embodiment, but can also be hexagonal or other shapes.

[0035] The flat-head design prevents the nail head 100 from forming a protrusion under the mucosa, reducing pressure and irritation on surrounding soft tissues, and reducing discomfort such as mucosal redness, swelling, and foreign body sensation. At the same time, the smooth surface can fit closely with the biomembrane, improving fixation stability and preventing the membrane edge from lifting. The anti-slip groove 110 can be used with special implantation instruments to prevent slippage during implantation, improving the accuracy and convenience of operation.

[0036] The length L of the nail body 200 is 3.0-6.0 mm, the diameter D is 1.3-1.8 mm, and the tip 210 is conical with a blunt structure. The blunt structure of the nail tip is hemispherical with a radius of 0.2-0.3 mm. The blunt tip avoids puncturing blood vessels, nerves, or damaging deep tissues during implantation, improving surgical safety, and is especially suitable for soft tissue areas rich in blood vessels and nerves within the oral cavity.

[0037] The surface of the staple body 200 can be smooth or threaded. In this embodiment, the surface of the staple body 200 is provided with a spiral thread 220, which is a continuous thread with a pitch of 0.3-0.5 mm and a depth of 0.1-0.2 mm. The continuous spiral thread 220 structure can enhance the interlocking force between the staple and soft tissue, improve fixation stability, and prevent displacement under mechanical loads such as chewing movements. At the same time, the spiral structure facilitates the implantation and removal of the staple (if early removal is required), reducing damage to surrounding tissues.

[0038] The biodegradable magnesium metal fixation pin for oral tissue fixation in this embodiment has the following beneficial effects: The degradation rate is precisely controllable, matching the healing cycle of oral soft tissue: This invention uses 99.99% high-purity magnesium as the base material, free from alloy element interference. Combined with the synergistic effect of the micro-arc oxidation film layer and the polydopamine / hydroxyapatite composite coating, the degradation cycle of the fixation pin in the weakly acidic environment of the oral cavity can be precisely controlled to 1-4 weeks, which is highly matched with the healing cycle of oral soft tissue. In the early stage of healing (1-2 weeks), the fixation pin maintains sufficient mechanical strength to provide stable fixation support for the biofilm. In the later stage of healing (2-4 weeks), the fixation pin gradually degrades, and the degradation products are pure magnesium ions, which can completely participate in human metabolism without any alloy impurities remaining. After the tissue has completely healed, the fixation pin has basically degraded and can be removed without secondary surgery, avoiding damage to the new tissue caused by suture removal and reducing patient pain.

[0039] With suitable mechanical properties and strong fixation stability, the magnesium alloy substrate of this invention has excellent mechanical strength (tensile strength ≥200MPa, yield strength ≥150MPa), which is far higher than that of existing polymer fixation nails. It can effectively resist the mechanical load generated by oral chewing movements and avoid fixation nail breakage and deformation. The continuous spiral pattern 220 structure on the surface of the nail body 200 can enhance the biting force with soft tissue. The nail head 100 presses the biomembrane to achieve a close fit between the membrane and the soft tissue. The fixation stability is significantly better than suture fixation and can effectively prevent complications such as membrane displacement, curling, and detachment.

[0040] Superior biocompatibility and extremely low tissue irritation: The 99.99% high-purity magnesium substrate has extremely high purity, with no alloy impurities added. The degradation products are only magnesium ions and water, with no toxic or harmful residues. Moreover, magnesium ions can participate in normal human physiological metabolism and are non-irritating to oral soft tissues. The polydopamine / hydroxyapatite composite coating has excellent biocompatibility with human tissues, which can further reduce the corrosion rate in the early stage of high-purity magnesium degradation and reduce local inflammatory reactions. At the same time, the porous structure of the micro-arc oxidation film layer is conducive to cell adhesion and proliferation, promotes tissue healing in the surgical area, and shortens the healing period. The flat-head 100 design of the staples avoids pressure protrusion on the submucosal tissue, further reducing the risk of tissue irritation and improving postoperative comfort.

[0041] Convenient operation, minimally invasive and safe, and comfortable postoperatively: This invention is equipped with a dedicated blunt drilling instrument. The procedure of drilling first and then hammering in the fixation nail reduces the difficulty of implantation and avoids excessive traction damage to soft tissues caused by direct implantation. The fixation nail has a flat-head design, which is suitable for submucosal implantation and avoids the nail head 100 protruding and compressing surrounding tissues, improving postoperative patient comfort. The tip of the nail body 200 has a blunt structure, which, together with drilling, further avoids damage to blood vessels and nerves. The anti-slip groove 110 on the nail head 100, in conjunction with the dedicated instrument, facilitates precise positioning and hammering, making the operation simple and quick, and significantly shortening the operation time. No sutures or suture membranes are required, reducing foreign body irritation, lowering the risk of infection, achieving minimally invasive fixation, and improving surgical safety.

[0042] Wide adaptability and high clinical application value: This invention provides fixation pins of various specifications, which can be adapted to oral soft tissue surgical wounds of different sizes and locations. It is suitable for various surgeries that require fixation of the implanted membrane, such as CGF surgery, gingival flap repair, and oral mucosal transplantation. It solves many drawbacks of existing fixation methods, can significantly improve surgical results, reduce the incidence of complications, and has broad prospects for clinical promotion and application.

[0043] This biodegradable magnesium metal fixation pin can be used in oral soft tissue surgeries, specifically in procedures requiring fixation of the implanted membrane, such as FGG surgery, gingival flap repair, and oral mucosal transplantation. The method is as follows: Preoperative preparation: Select biodegradable magnesium metal fixation nails of appropriate specifications according to the size of the surgical wound and the size of the implanted membrane, and sterilize the fixation nails and special implantation instruments for later use. Membrane placement: After cleaning the oral surgical area, the free connective tissue and biomembrane are laid flat on the wound or the area to be repaired. The position of the membrane is adjusted to ensure that the membrane adheres closely to the soft tissue. Fixation procedure: First, align the special drilling instrument with the area where the membrane and soft tissue adhere. Adjust the drilling depth according to the length of the fixation pin (the drilling depth should be 0.5-1.0 mm shallower than the length of the pin 200). Slowly drill to form a pin hole that fits the pin 200. After drilling, align the special implantation instrument with the anti-slip groove 110 on the fixation pin cap 100. Hold the instrument and align the tip of the pin 200 with the pin hole. Gently tap the tail of the instrument to allow the pin 200 to embed into the soft tissue along the pin hole. Ensure that the smooth lower surface of the flat-headed pin cap 100 presses firmly against the biomembrane without any protrusions or pressure. Depending on the size of the membrane, evenly distribute 3-6 fixation pins at the edges and center of the membrane to achieve comprehensive fixation. (Note: Use a blunt drill bit with a diameter 0.1-0.2 mm smaller than the bottom diameter of the pin 200 to avoid drilling too large a hole that could cause loosening and to reduce soft tissue damage.)

[0044] Postoperative observation: After implantation, check the fixation of the membrane. After confirming that there is no displacement or curling, routinely suture the soft tissue at the edge of the surgical area (no need to suture the membrane itself). Postoperatively, follow the routine anti-infection care. There is no need to remove the fixation pins a second time. The fixation pins degrade slowly in the oral environment, and the degradation products participate in human metabolism.

[0045] This invention provides fixation pins of various specifications, which can be adapted to oral soft tissue surgical wounds of different sizes and locations. It is suitable for various surgeries that require fixation of the implanted membrane, such as CGF surgery, gingival flap repair, and oral mucosal transplantation. It solves many drawbacks of existing fixation methods, can significantly improve surgical results, reduce the incidence of complications, and has broad prospects for clinical application.

[0046] Example 2 A biodegradable magnesium metal fixation pin for fixing oral tissues is identical in structure to that of Example 1, except that the pin head is circular, preferably with a diameter of 2.0-5.0 mm. It should be noted that the pin head is not limited to the circular shape of this embodiment; it can also be elliptical or other shapes.

[0047] This biodegradable magnesium metal fixation pin for oral tissue fixation features a reasonable structural design, excellent mechanical properties, and controllable degradation behavior.

[0048] Example 3 A method for preparing a biodegradable magnesium metal fixation pin for oral tissue fixation, as described in Example 1 or 2, includes the following steps: S1, ingredient preparation and smelting, specifically: Select high-purity magnesium raw materials with a purity of ≥99.99%, remove the surface oxide scale, and put them into a vacuum induction melting furnace. Under argon protection, melt at 650-700℃ for 20-40 minutes. After stirring evenly, hold at 630-650℃ for 15-25 minutes, pour into a mold, and cool to room temperature to obtain high-purity magnesium ingots. S2, forging and rolling, specifically: High-purity magnesium ingots are hot-forged at 300-400℃ with a deformation of 40-60%, and then cold-rolled at 280-320℃ with a deformation of 30-50% to obtain high-purity magnesium plates or bars. S3, machining, specifically: Magnesium alloy sheets or bars are machined to produce a fixed nail blank in which the nail head and nail body are integrally formed, and spiral patterns, blunt tips and anti-slip grooves are processed. S4, surface micro-arc oxidation treatment, specifically: The fixing nail blank is placed in a micro-arc oxidation electrolyte for micro-arc oxidation treatment, forming an oxide film layer on the nail surface. S5, preparation of the composite coating, specifically: The fixing pins that form the oxide film are immersed in a polydopamine solution to form a polydopamine film; then hydroxyapatite is deposited by electrophoretic deposition and sintered to form a polydopamine / hydroxyapatite composite coating. S6, Cleaning and Sterilization, specifically: The fixation nails are ultrasonically cleaned and sterilized by irradiation to obtain the finished product.

[0049] The preparation method of the biodegradable magnesium metal fixation nail, The electrolyte is composed of sodium silicate, sodium phosphate and sodium hydroxide, and the solvent is deionized water. The concentration of sodium silicate in the electrolyte is 8-12 g / L, the concentration of sodium phosphate is 3-8 g / L and the concentration of sodium hydroxide is 1-3 g / L. The surface micro-arc oxidation process of S4 is as follows: The fixing nail blank is placed in the electrolyte, with the fixing nail blank as the anode and the stainless steel plate as the cathode. Micro-arc oxidation is carried out using a pulse power supply at a voltage of 300-400V and a current density of 10-20A / dm². The treatment time is 10-30min, and the electrolysis temperature is controlled below 35℃. After processing, remove the fixing nail, rinse it with deionized water, and let it air dry to form an oxide film on the nail surface.

[0050] Dissolve 1-5 g of polydopamine in 100-200 mL of Tris-HCl buffer solution with pH=8.0-9.0, and stir until completely dissolved to prepare a polydopamine solution. Hydroxyapatite powder with a particle size of 30-60 nm was ultrasonically dispersed in deionized water at a concentration of 15-30 g / L, and 0.2-1.0 g / L of dispersant was added to prepare a hydroxyapatite suspension. The specific process for preparing the composite coating of S5 is as follows: The fixation nails treated with micro-arc oxidation are placed in a polydopamine solution and immersed in a constant temperature oven at 30-40℃ for 1-5 hours. After removal, they are rinsed with deionized water and air-dried naturally to form a polydopamine film on the nail surface. The fixing pins were placed in a hydroxyapatite suspension, and hydroxyapatite was deposited by electrophoretic deposition at a voltage of 10-20V and a deposition temperature of 20-30℃ for 5-10 minutes. After deposition, the fixing pins were placed in a muffle furnace, heated to 400-500℃, and held for 1.0-2.0 h for sintering. After cooling to room temperature, a polydopamine / hydroxyapatite composite coating with a thickness of 10-20 μm was obtained.

[0051] The biodegradable magnesium metal fixation nail for oral tissue fixation prepared by the preparation method of this embodiment has the following beneficial effects: the degradation rate is precisely controllable and matches the healing cycle of oral soft tissue. It has suitable mechanical properties and strong fixation stability; it has better biocompatibility and extremely low tissue irritation; it is easy to operate, minimally invasive and safe, and comfortable after surgery; it has wide applicability and high clinical application value.

[0052] Example 4 A method for preparing a biodegradable magnesium metal fixation pin for oral tissue fixation, as described in Example 1 or 2, includes the following steps: S1, Ingredients and Smelting: High-purity magnesium raw materials with a purity of ≥99.99% are selected, and the surface oxide scale is removed to ensure that no impurities are mixed in. The high-purity magnesium raw materials are placed in a vacuum induction melting furnace, and argon gas is introduced for protection (argon gas flow rate is 0.5L / min). The temperature is raised to 680℃ and melted for 30 minutes, during which time it is stirred 3 times, each time for 5 minutes, at a stirring speed of 300r / min. Then, it is held at 640℃ for 20 minutes and cast into a pre-made metal mold. It is then allowed to cool naturally to room temperature to obtain high-purity magnesium ingots.

[0053] S2, Forging and Rolling: Magnesium alloy ingots are placed in a heating furnace, heated to 380℃, and held for 1 hour. Then, hot forging is performed at a forging pressure of 500 MPa and a deformation of 50% to obtain forgings. After the forgings are cooled to room temperature, they are placed back into the heating furnace, heated to 320℃, and held for 30 minutes. Cold rolling is then performed at a rolling speed of 1 m / min and a deformation of 40% to obtain magnesium alloy sheets with a thickness of 5 mm.

[0054] S3, Machining: A CNC lathe is used to process high-purity magnesium sheet into a fixed nail blank with the nail head and nail body integrally formed. The nail head is flat and round, with a diameter of 2.5 mm and a thickness of 0.8 mm. The lower surface of the nail head is machined into a smooth plane (roughness Ra=0.6μm), and the upper surface is machined with a cross-shaped anti-slip groove with a groove depth of 0.15 mm. The nail body is conical, with a length of 4.5 mm and a bottom diameter of 1.2 mm. Continuous spiral patterns are machined on the surface of the nail body with a pitch of 0.4 mm and a depth of 0.15 mm. The tip of the nail body is machined into a hemispherical blunt structure with a radius of 0.25 mm. After machining, the surface of the fixed nail is sanded with sandpaper to remove burrs, resulting in a smooth fixed nail blank.

[0055] S4, Surface micro-arc oxidation treatment: A micro-arc oxidation electrolyte was prepared, with sodium silicate concentration of 10 g / L, sodium phosphate concentration of 5 g / L, sodium hydroxide concentration of 2 g / L, and deionized water as the solvent.

[0056] The fixing nail blank is placed in the electrolyte, with the fixing nail blank as the anode and the stainless steel plate as the cathode. Micro-arc oxidation is performed using a pulse power supply at a voltage of 350V, a current density of 15A / dm², and a treatment time of 15min. The electrolysis temperature is controlled below 30℃. After the treatment, the fixing nail is removed, rinsed with deionized water, and air-dried. An oxide film layer with a thickness of 10μm is formed on the surface of the nail body. The porous structure on the surface of the oxide film layer has a pore size of 2-4μm.

[0057] S5, Preparation of composite coating: Prepare a polydopamine solution by dissolving 1g of polydopamine in 100mL of Tris-HCl buffer (pH=8.5) and stirring until completely dissolved. Place the micro-arc oxidation-treated fixation pins into the polydopamine solution and immerse them in a 37℃ constant temperature oven for 3 hours. After removing them, rinse them with deionized water and air dry them naturally to form a polydopamine film on the surface of the pins.

[0058] A hydroxyapatite suspension was prepared by ultrasonically dispersing hydroxyapatite powder (particle size 50 nm) in deionized water at a concentration of 20 g / L, with 0.5 g / L of dispersant (sodium dodecyl sulfate). Fixing pins were placed in the hydroxyapatite suspension, and hydroxyapatite was deposited using electrophoretic deposition at a voltage of 15 V, a deposition time of 8 min, and a deposition temperature of 25 °C. After deposition, the fixing pins were placed in a muffle furnace, heated to 450 °C, and held at that temperature for 1.5 h for sintering. After cooling to room temperature, a polydopamine / hydroxyapatite composite coating with a thickness of 15 μm (where the hydroxyapatite mass fraction was 40%) was obtained.

[0059] S6, Cleaning and Sterilization: The prepared fixation pins were placed in deionized water and ultrasonically cleaned for 12 minutes (ultrasonic power of 300W) to remove residual impurities on the surface; after vacuum drying, they were sterilized by radiation; after sterilization, the finished biodegradable magnesium metal fixation pins were obtained.

[0060] The preparation method of this embodiment can prepare the biodegradable magnesium metal fixation pins for oral tissue fixation of Example 1 or 2. The prepared biodegradable magnesium metal fixation pins for oral tissue fixation have the characteristics of reasonable structural design, excellent mechanical properties, and controllable degradation behavior.

[0061] Example 5 Biodegradable magnesium metal fixation pins for fixing oral tissues are used in clinical applications.

[0062] Ten patients requiring CGF surgery were selected. All patients had gingival defects with exposed bone, with defect areas ranging from 1.0cm × 1.5cm to 2.0cm × 2.5cm. The collagen membrane was fixed using biodegradable magnesium metal staples as described in Example 1 or 2. The specific procedure is as follows: 1. Preoperative preparation: Based on the size of the patient's wound, select biodegradable magnesium metal fixation nails with a length of 4.5 mm and a bottom diameter of 1.2 mm. Prepare 4 fixation nails for each patient. Prepare a dedicated blunt drilling instrument (1.0 mm diameter drill bit, adjustable drilling depth), implantation instrument, and sterile hammer. Sterilize all instruments and fixation nails together in an autoclave (121℃, 0.1 MPa) for 20 minutes.

[0063] 2. Surgical procedure: Routine disinfection and draping, local infiltration anesthesia; clean the surgical area, remove necrotic tissue, and prepare a fresh wound; apply CGF gel evenly to the wound, then lay the collagen membrane flat on the surface of the CGF gel, adjust the position of the membrane to ensure that the membrane completely covers the wound and adheres to the surrounding soft tissue.

[0064] 3. Fixation Procedure: Before the procedure, sterilize the dedicated blunt drilling instrument (1.0mm diameter drill bit, 0.2mm smaller than the diameter of the nail body at the bottom) and the fixation nail together. During the procedure, first align the drilling instrument with the area where the membrane and soft tissue meet, and slowly drill a hole. The drilling depth should be controlled at 3.5-4.0mm (0.5mm shallower than the nail body length) to create a nail hole that fits the nail body. Avoid excessive force during drilling to prevent damage to deep tissues. After drilling, remove the drilling instrument and align the dedicated implantation instrument with the cross-shaped anti-slip groove on the fixation nail head. Hold the instrument and align the tip of the nail body with the nail hole. Gently tap the tail of the instrument with a sterile hammer to allow the nail body to embed into the soft tissue along the nail hole. The implantation depth should be consistent with the drilling depth, ensuring that the smooth lower surface of the flat-head nail head presses firmly against the collagen membrane, and that the membrane and soft tissue are closely adhered without any protrusions or pressure. Insert one fixation nail at each of the four edges of the membrane to achieve uniform fixation.

[0065] 4. Postoperative care: After implantation, check that the collagen membrane is not displaced or curled. Routinely suture the gingival tissue at the surgical site margin, apply pressure to stop bleeding, and apply iodine glycerin. Postoperatively, administer antibiotics to prevent infection. Instruct the patient to eat warm, soft foods for one week after surgery, avoid chewing hard foods, and have regular follow-up examinations.

[0066] 5. Postoperative observation: One week after surgery, the patient's surgical area showed no redness, swelling, or bleeding. The collagen membrane was firmly fixed without exposure or detachment. The flat-headed screw caps did not form submucosal protrusions, and the patient had no obvious foreign body sensation. Two weeks after surgery, the wound began to heal, and the collagen membrane fused well with the surrounding tissue. Four weeks after surgery, the wound was completely healed, gingival tissue regeneration was good, and the high-purity magnesium fixation screws had basically degraded without any impurities remaining. Three months after surgery, the gingival morphology returned to normal, no complications occurred, and the surgical effect was excellent.

[0067] The fixation pin provided by this invention is suitable for various surgeries that require fixation of the implanted membrane, such as CGF surgery, gingival flap repair, and oral mucosal transplantation. It solves many drawbacks of existing fixation methods, can significantly improve surgical results, reduce the incidence of complications, and has broad prospects for clinical application.

[0068] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A biodegradable magnesium metal fixation pin for fixing oral tissues, comprising a pin head and a pin body, characterized in that: The fixing pin is made entirely of 99.9-99.99% high-purity magnesium base material, with no alloying elements added and an impurity content of ≤0.01%. The surface of the fixing nail is sequentially coated with an oxide film layer and a polydopamine / hydroxyapatite composite coating.

2. The biodegradable magnesium metal fixation screw for oral tissue fixation according to claim 1, characterized in that: The oxide film layer has a thickness of 5-15 μm and a porous structure with a pore size of 1-5 μm on its surface.

3. The biodegradable magnesium metal fixation screw for oral tissue fixation according to claim 2, characterized in that: The oxide film layer is prepared by a micro-arc oxidation process.

4. The biodegradable magnesium metal fixation pin for oral tissue fixation according to claim 2 or 3, characterized in that: The thickness of the polydopamine / hydroxyapatite composite coating is 10-20 μm, wherein the mass fraction of hydroxyapatite is 30-50%.

5. The biodegradable magnesium metal fixation pin for oral tissue fixation according to claim 4, characterized in that: The nail head is flat-headed, with a thickness of 0.5-1.0mm. The upper surface of the nail head has an anti-slip groove for matching the screwdriver, and the lower surface is a flat structure. The nail body has a length of 3.0-6.0 mm, a diameter of 1.3-1.8 mm, a conical tip, and a blunt tip structure.

6. The biodegradable magnesium metal fixation pin for oral tissue fixation according to claim 5, characterized in that: The surface of the nail body is provided with spiral patterns, with a pitch of 0.3-0.5 mm and a depth of 0.1-0.2 mm.

7. The biodegradable magnesium metal fixation pin for oral tissue fixation according to claim 6, characterized in that: The nail head is round or oval, and when the nail head is round, the diameter is 2.0-5.0 mm; The anti-slip groove on the upper surface of the nail head is cross-shaped or hexagonal, and the groove depth is 0.1-0.2mm; The lower surface of the nail head is a smooth plane with a surface roughness Ra≤0.8μm; The blunt structure at the tip of the nail is hemispherical with a radius of 0.2-0.3 mm.

8. A method for preparing a biodegradable magnesium metal fixation pin as described in any one of claims 1-7, characterized in that: Includes the following steps: S1, ingredient preparation and smelting, specifically: Select high-purity magnesium raw materials with a purity of ≥99.99%, remove the surface oxide scale, and put them into a vacuum induction melting furnace. Under argon protection, melt at 650-700℃ for 20-40 minutes. After stirring evenly, hold at 630-650℃ for 15-25 minutes, pour into a mold, and cool to room temperature to obtain high-purity magnesium ingots. S2, forging and rolling, specifically: High-purity magnesium ingots are hot-forged at 300-400℃ with a deformation of 40-60%, and then cold-rolled at 280-320℃ with a deformation of 30-50% to obtain high-purity magnesium plates or bars. S3, machining, specifically: Magnesium alloy sheets or bars are machined to produce a fixed nail blank in which the nail head and nail body are integrally formed, and spiral patterns, blunt tips and anti-slip grooves are processed. S4, surface micro-arc oxidation treatment, specifically: The fixing nail blank is placed in a micro-arc oxidation electrolyte for micro-arc oxidation treatment, forming an oxide film layer on the nail surface. S5, the preparation of the composite coating, specifically: The fixing pins that form the oxide film are immersed in a polydopamine solution to form a polydopamine film; then hydroxyapatite is deposited by electrophoretic deposition and sintered to form a polydopamine / hydroxyapatite composite coating. S6, Cleaning and Sterilization, specifically: The fixation nails are ultrasonically cleaned and sterilized by irradiation to obtain the finished product.

9. The method for preparing the biodegradable magnesium metal fixation pin according to claim 8, characterized in that: The electrolyte is composed of sodium silicate, sodium phosphate and sodium hydroxide, and the solvent is deionized water. The concentration of sodium silicate in the electrolyte is 8-12 g / L, the concentration of sodium phosphate is 3-8 g / L and the concentration of sodium hydroxide is 1-3 g / L. The surface micro-arc oxidation process of S4 is as follows: The fixing nail blank is placed in the electrolyte, with the fixing nail blank as the anode and the stainless steel plate as the cathode. Micro-arc oxidation is carried out using a pulse power supply at a voltage of 300-400V and a current density of 10-20A / dm². The treatment time is 10-30min, and the electrolysis temperature is controlled below 35℃. After processing, remove the fixing nail, rinse it with deionized water, and let it air dry to form an oxide film on the nail surface. Dissolve 1-5 g of polydopamine in 100-200 mL of Tris-HCl buffer solution with pH=8.0-9.0, and stir until completely dissolved to prepare a polydopamine solution. Hydroxyapatite powder with a particle size of 30-60 nm was ultrasonically dispersed in deionized water at a concentration of 15-30 g / L, and 0.2-1.0 g / L of dispersant was added to prepare a hydroxyapatite suspension. The specific process for preparing the composite coating of S5 is as follows: The fixation pins treated with micro-arc oxidation are placed in a polydopamine solution and immersed in a constant temperature oven at 30-40℃ for 1-5 hours. After removal, they are rinsed with deionized water and air-dried naturally to form a polydopamine film on the surface of the pins. The fixing pins were placed in a hydroxyapatite suspension, and hydroxyapatite was deposited by electrophoretic deposition at a voltage of 10-20V and a deposition temperature of 20-30℃ for 5-10 minutes. After deposition, the fixing pins are placed in a muffle furnace, heated to 400-500℃, held for 1.0-2.0 h, and sintered. After cooling to room temperature, a polydopamine / hydroxyapatite composite coating with a thickness of 10-20 μm is obtained.

10. The method for preparing the biodegradable magnesium metal fixing nail according to claim 9, characterized in that: The electrolyte contains 10 g / L sodium silicate, 5 g / L sodium phosphate, and 2 g / L sodium hydroxide. During the surface micro-arc oxidation process of S4, a pulse power supply was used to perform micro-arc oxidation under the conditions of 350V voltage and 15A / dm² current density for 15 minutes, and the electrolysis temperature was controlled below 30℃. Dissolve 1g of polydopamine in 100mL of Tris-HCl buffer solution with pH=8.5 and stir until completely dissolved to prepare a polydopamine solution. Hydroxyapatite powder with a particle size of 50 nm was ultrasonically dispersed in deionized water at a concentration of 20 g / L, and 0.5 g / L of dispersant was added to prepare a hydroxyapatite suspension. The specific process for preparing the composite coating of S5 is as follows: The fixation pins treated with micro-arc oxidation were placed in a polydopamine solution and immersed in a constant temperature oven at 37°C for 3 hours. After being removed, they were rinsed with deionized water and air-dried naturally to form a polydopamine film on the surface of the pins. The fixing pins were placed in a hydroxyapatite suspension, and hydroxyapatite was deposited for 8 minutes using electrophoretic deposition at a voltage of 15V and a deposition temperature of 25℃. After deposition, the fixing pins are placed in a muffle furnace, heated to 450℃, held for 1.5 hours, and sintered. After cooling to room temperature, a polydopamine / hydroxyapatite composite coating with a thickness of 15μm is obtained.

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