An antibacterial metal preformed crown and its preparation method

Abstract

The present invention discloses an antibacterial metal prefabricated crown and a preparation method thereof, which are applied to the technical fields of biomaterials and laser processing. The antibacterial metal prefabricated crown of the present invention includes a stainless steel finished prefabricated crown and silver fish-shaped nanostructures attached to the surface of the stainless steel finished prefabricated crown and distributed in a close-packed regular pattern. The present invention uses an ultrafast laser technology to process the metal prefabricated crown, and the preparation method is efficient and environmentally friendly. The ultrafast laser has the characteristics of strong universality, high processing precision and strong controllability; a nano-stripe structure is formed on the surface of the metal prefabricated crown, which has good periodic repeatability and greatly improves the hydrophobic performance of the material; the nano-stripe structure can reduce the adhesion of bacteria, inhibit the formation of plaque biofilm, and exhibits good biocompatibility, which has a positive effect on maintaining periodontal health and preventing dental caries, and has a wide clinical application prospect.

Description

Technical Field

[0001] The present invention relates to the technical fields of biomaterials and laser processing technology, and more specifically to an antibacterial metal prefabricated crown and a preparation method thereof. Background Art

[0002] Dental caries in primary teeth is one of the most common chronic diseases in children's oral cavity. Untreated dental caries has adverse effects on children's growth and development, mental health, etc. Metal prefabricated crowns are currently the main materials for repairing large-area dental caries in primary molars and young permanent molars. They have the advantages of less tooth preparation amount, simple operation method, and good restoration of tooth shape and function. However, compared with customized restorations, the marginal fit of metal prefabricated crowns is poor, and microleakage is likely to occur, leading to the generation of secondary caries. In addition, the surface free energy of metal materials is relatively high, which is easy to adhere to dental plaque and stimulate the periodontal tissue to produce inflammation. Therefore, whether it is possible to optimize the material properties of stainless steel prefabricated crowns to make them have suitable antibacterial properties and good biocompatibility is a clinical problem that pediatric dentists are more concerned about.

[0003] So far, in order to reduce the attachment of microorganisms on the material surface, methods such as using antibacterial metal elements, reactive oxygen species, and organic functional groups are often used to treat the material to kill and decompose bacteria. However, these chemical methods usually cannot prevent bacteria from adhering for a long time, and even have potential toxicity to the body. Therefore, developing a metal prefabricated crown with both antibacterial properties and biocompatibility has important clinical significance. At present, many studies have begun to focus on changing the physical morphology of the material surface rather than chemical modification to play an antibacterial role. Among them, materials with nanostructures can have the characteristics required for biomedical applications, such as anti-biofouling and antibacterial properties. This is a surface antibacterial strategy that causes bacteria to be interfered with their microbial adhesion and biological activity by mechanical stress through a physical structure similar to the geometric size of bacteria, and it is a pure physical antibacterial method. The preparation methods of nanostructures include high-energy beam etching (lithography, electron beam etching, ion beam etching), imprinting, self-assembly, chemical corrosion, chemical synthesis, sputtering deposition, templates, etc. Among them, the ultrafast laser etching method is an efficient and fast engineering method. Ultrafast laser refers to a laser with a laser pulse width in the range of dozens of femtoseconds to ten picoseconds, generally including femtosecond laser and picosecond laser. It has an extremely short pulse width, an extremely high instantaneous energy density, and an extremely short action time. When the ultrafast laser acts on the metal material, it will prepare delicate nanostructures on the material surface through mechanisms such as ablation, induction, phase explosion, or Coulomb explosion, which is an efficient and precise nanostructure preparation means.

[0004] Therefore, proposing an antibacterial metal prefabricated crown and a preparation method thereof to solve the difficulties existing in the prior art is an urgent problem to be solved by those skilled in the art. Summary of the Invention

[0005] In view of this, the present invention provides an antibacterial metal prefabricated crown and a preparation method thereof, which overcome the technical problem of the insufficient antibacterial ability of the existing metal prefabricated crowns.

[0006] In order to achieve the above object, the present invention provides the following technical solutions:

[0007] An antibacterial metal prefabricated crown, the antibacterial metal prefabricated crown includes a stainless steel finished prefabricated crown and silver fish-shaped nanostructures attached to the surface of the stainless steel finished prefabricated crown and distributed in a close-packed regular pattern.

[0008] Further, the silver fish-shaped nanostructures are close-packed and alternating silver fish-shaped protrusions and conforming strip-shaped grooves.

[0009] Further, the width of the silver fish-shaped protrusions is 250 - 650 nanometers, the length is 1500 - 6000 nanometers, and the height is 300 - 600 nanometers.

[0010] Further, nano-particles are randomly and discretely distributed on the silver fish-shaped protrusions, and the size of the nano-particles is 70 - 500 nanometers.

[0011] Further, the width of the conforming strip-shaped grooves is 200 - 450 nanometers, the length is 1500 - 6000 nanometers, and the depth is 300 - 600 nanometers.

[0012] The present invention provides a preparation method of an antibacterial metal prefabricated crown, including the following steps:

[0013] S1. Place the stainless steel finished prefabricated crown in an acetone and alcohol solution for ultrasonic cleaning to remove dust, oil stains, and fingerprints on the surface of the stainless steel finished prefabricated crown, and dry it for standby;

[0014] S2. Place the stainless steel finished prefabricated crown on the focal plane of a laser processing device;

[0015] S3. Use an ultrafast laser-induced ablation composite mechanism to process the stainless steel finished prefabricated crown, thereby obtaining the silver fish-shaped nanostructures distributed in a close-packed regular pattern.

[0016] Further, the laser processing device in S2 is composed of an ultrafast laser, a beam expander, a 45° reflector, a scanning galvanometer, and a focusing field lens, and the focal depth of the focused beam of the focusing field lens is 0 - 10 mm.

[0017] Further, the stainless steel finished prefabricated crown is fixed by a clamping mechanism, and the clamping mechanism is composed of a multi-axis motor and a support rod.

[0018] Furthermore, in the ultrafast laser-induced ablation composite mechanism in S3, the induction mechanism is the main one, forming the silverfish-shaped protrusions and the conformal strip-shaped grooves arranged in a close-packed pattern; the ablation mechanism is the auxiliary one, and the nanoparticles are randomly and discretely distributed on the silverfish-shaped protrusion structure formed.

[0019] Furthermore, the ultrafast laser is a femtosecond laser or a picosecond laser, and its wavelength ranges from infrared light, visible light to ultraviolet light.

[0020] Advantages of the present invention:

[0021] (1) The present invention uses ultrafast laser technology to process metal preformed crowns, and the preparation method is efficient and environmentally friendly. Ultrafast lasers have the characteristics of strong universality, high processing accuracy and strong controllability, and are an ideal method for preparing nanostructures;

[0022] (2) The present invention forms a nanostripe structure on the surface of the metal preformed crown, which has good periodic repeatability and greatly improves the hydrophobic performance of the material;

[0023] (3) The nanostripe structure of the present invention can reduce the adhesion of bacteria, inhibit the formation of plaque biofilm, and exhibits good biocompatibility, which has a positive effect on maintaining periodontal health and preventing dental caries, and has a wide clinical application prospect. Description of the drawings

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only the embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained according to the provided drawings.

[0025] Figure 1 Schematic diagram of the antibacterial metal preformed crown prepared in Embodiments 1-5 of the present invention;

[0026] Figure 2 Schematic diagram of the special device for ultrafast laser treatment of the preformed crown and the clamping and moving mechanism provided by the present invention;

[0027] Figure 3 Scanning electron microscope images of the blank stainless steel material in vitro test and the nanostripe structure prepared by ultrafast laser according to the embodiments of the present invention; among them, a1 is the blank untreated stainless steel, a2 is the enlarged view of the blank untreated stainless steel, b1 is the stainless steel treated in the embodiment, and b2 is the stainless steel treated in the embodiment;

[0028] Figure 4Wettability comparison diagram of the nano-stripe structure prepared in the embodiment of the present invention for in vitro testing; among them, a is untreated stainless steel, and b is stainless steel treated in the embodiment.

[0029] Figure 5 Scanning electron microscope result diagram of the antibacterial performance of the nano-stripe structure prepared in the embodiment of the present invention for in vitro testing; among them, a1 is the adhesion result of Streptococcus mutans on untreated stainless steel, a2 is the adhesion result of Streptococcus mutans on untreated stainless steel, a3 is the adhesion result of Fusobacterium nucleatum on untreated stainless steel, b1 is the adhesion result of Streptococcus mutans on the nano-stripe structure prepared in the embodiment of the present invention, b2 is the adhesion result of Streptococcus mutans on untreated stainless steel, and b3 is the adhesion result of Fusobacterium nucleatum on untreated stainless steel;

[0030] Figure 6 Results diagram of dead / live bacteria staining laser confocal microscope for testing the antibacterial performance of the nano-stripe structure prepared in the embodiment of the present invention in vitro; among them, a1 is the adhesion result of Streptococcus mutans on untreated stainless steel, a2 is the adhesion result of Streptococcus mutans on untreated stainless steel, a3 is the adhesion result of Fusobacterium nucleatum on untreated stainless steel, b1 is the adhesion result of Streptococcus mutans on the nano-stripe structure prepared in the embodiment of the present invention, b2 is the adhesion result of Streptococcus mutans on untreated stainless steel, and b3 is the adhesion result of Fusobacterium nucleatum on untreated stainless steel;

[0031] Figure 7 Biocompatibility results of untreated stainless steel and the nano-stripe structure prepared in the embodiment of the present invention for in vitro testing;

[0032] Figure 8 Appearance diagram of the ultrafast laser treatment on the surface of the finished metal preformed crown in the embodiment of the present invention;

[0033] Figure 9 q-PCR detection result of the number of bacteria attached to the surface of the metal preformed crown in the embodiment of the present invention for animal experiment testing.

[0034] Among them, 1 - ultrafast laser, 2 - beam expander, 3 - 45° reflector, 4 - scanning galvanometer, 5 - focusing field lens, 6 - multi-axis motor, 7 - support rod, 8 - antibacterial metal preformed crown, 81 - stainless steel finished preformed crown, 82 - silver fish-shaped nano-structure. Detailed implementation manners

[0035] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0036] See Figure 1 As shown, the present invention discloses an antibacterial metal prefabricated crown. The antibacterial metal prefabricated crown 8 includes a stainless steel finished prefabricated crown 81 and silver fish-shaped nanostructures 82 attached to the surface of the stainless steel finished prefabricated crown 81 and distributed in a close-packed regular pattern.

[0037] In the present invention, the silver fish-shaped nanostructures 82 are close-packed alternating silver fish-shaped protrusions and conforming strip-shaped grooves.

[0038] In the present invention, the width of the silver fish-shaped protrusions is 250 - 650 nanometers, the length is 1500 - 6000 nanometers, and the height is 300 - 600 nanometers.

[0039] In the present invention, nano-particles are randomly and discretely distributed on the silver fish-shaped protrusions, and the size of the nano-particles is 70 - 500 nanometers.

[0040] In the present invention, the width of the conforming strip-shaped grooves is 200 - 450 nanometers, the length is 1500 - 6000 nanometers, and the depth is 300 - 600 nanometers.

[0041] The present invention also provides a preparation method for an antibacterial metal prefabricated crown, including the following steps:

[0042] S1. Place the stainless steel finished prefabricated crown in an acetone and alcohol solution for ultrasonic cleaning to remove dust, oil stains, and fingerprints on the surface of the stainless steel finished prefabricated crown, and dry it for standby;

[0043] S2. Place the stainless steel finished prefabricated crown on the focal plane of the laser processing device;

[0044] S3. Use the ultrafast laser-induced ablation composite mechanism to process the stainless steel finished prefabricated crown to obtain silver fish-shaped nanostructures distributed in a close-packed regular pattern.

[0045] In the present invention, the laser processing device in S2 is composed of an ultrafast laser, a beam expander, a 45° reflecting mirror, a scanning galvanometer, and a focusing field lens. The focal depth of the focused beam of the focusing field lens is 0 - 10 mm.

[0046] In the present invention, the stainless steel finished prefabricated crown is fixed by a clamping mechanism, and the clamping mechanism is composed of a multi-axis motor and a support rod.

[0047] In the present invention, the ultrafast laser-induced ablation composite mechanism in S3 is mainly an induction mechanism, forming closely arranged silverfish-shaped protrusions and conforming strip-shaped grooves; the ablation mechanism is supplemented, and nanoparticles are randomly and discretely distributed on the silverfish-shaped protrusion structure.

[0048] In the present invention, the ultrafast laser is a femtosecond laser or a picosecond laser, and its wavelength ranges from infrared light, visible light to ultraviolet light.

[0049] In the present invention, the femtosecond laser has a pulse width of 60 - 900 femtoseconds, a repetition frequency of 10K - 1MHz, an average power of 0.1W - 10W, a scanning speed of 100mm - 1000mm / s, a spot size of 10 - 100 microns, and scans and covers the entire surface in a multi-track overlapping manner, with an overlapping rate of 10 - 50%.

[0050] In the present invention, the picosecond laser has a pulse width of 1 - 10 picoseconds, a repetition frequency of 100K - 2MHz, an average power of 1W - 20W, a scanning speed of 500mm - 2000mm / s, a spot size of 50 - 300 microns, and scans and covers the entire surface in a multi-track overlapping manner, with an overlapping rate of 10 - 50%.

[0051] The technical solutions provided by the present invention will be described in detail below in conjunction with the embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0052] Example 1:

[0053] (1) Place the finished stainless steel prefabricated crown (including but not limited to the 3M ESPE stainless steel prefabricated crown) in an acetone and alcohol solution for conventional ultrasonic cleaning to remove possible residues such as dust, oil stains, fingerprints, etc. on the surface, and dry it after cleaning.

[0054] (2) Place this type of finished stainless steel prefabricated crown on the holder of the dedicated laser processing device shown in Figure 2 The holder is placed on the laser focal plane, and the focal plane is scanned by the focus of the ultrafast laser 1 through the beam expander 2, the 45° mirror 3, the scanning galvanometer 4, and the focusing field lens 5. The focal depth of the focused beam by the focusing field lens is 0 - 10mm, preferably 0 - 3mm.

[0055] (3) The prefabricated crown holder is driven by a multi-axis motor 6 and a support rod 7 to rotate, move forward and backward, and move up and down, so as to ensure that the key parts of the periphery and top of the prefabricated crown are located within the above-mentioned focal plane and are covered by laser beam scanning. The stainless steel prefabricated crown is processed by using the ultrafast laser-induced ablation composite mechanism. Femtosecond laser is used for processing, and its wavelength can be infrared, visible light or ultraviolet, preferably the infrared wavelength of 1030 nm, the pulse width can be 60 - 900 femtoseconds, preferably 500 femtoseconds, the repetition frequency can be 10K - 1MHz, preferably 400KHz, the average power can be 0.1W - 10W, preferably 4W, the scanning speed is 100mm - 1000mm / s, preferably 400mm / s, the spot size is 10 - 100 microns, preferably 50 microns, and the whole surface is scanned and covered in a multi-track overlapping manner, and the overlapping rate is 10 - 50%, preferably 30%. After the above laser treatment, a densely arranged and regularly distributed silver fish-shaped nanostructure can be obtained on the entire surface of the stainless steel finished prefabricated crown.

[0056] Example 2:

[0057] Material Characterization of Stainless Steel Treated by Ultrafast Laser

[0058] (1) Stainless steel was used as the research object. Before laser treatment, the samples were first cut into circular specimens of 10×2 mm, and then polished with sandpaper in gradients. The polished materials were ultrasonically cleaned and naturally dried at room temperature as in vitro experimental samples.

[0059] (2) The above in vitro experimental samples were treated by ultrafast laser, and the surface morphology of the materials was observed by scanning electron microscopy. The results are shown in Figure 3 As shown, where a1 is the untreated stainless steel, a2 is the enlarged view of the untreated stainless steel, b1 is the stainless steel treated in the example, and b2 is the stainless steel treated in the example. The results show laser-induced periodic structures with a period between 400 - 700 nm. The liquid contact angle experiment was used to test the wettability of the materials. The results are shown in Figure 4 As shown, where a is the untreated stainless steel and b is the stainless steel treated in the example. The results show that the hydrophobicity of the material increases after ultrafast laser treatment.

[0060] Example 3:

[0061] Verification of Antibacterial Properties of Stainless Steel Treated by Ultrafast Laser

[0062] (1) After the samples in Test Example 1 were sterilized, they were placed in a 24-well plate, and 1 mL of Streptococcus mutans, Porphyromonas gingivalis, and Fusobacterium nucleatum suspensions (106 CFU / mL) were added respectively. They were cultured in an incubator for 48 hours, rinsed with deionized water, and the adhesion and aggregation of bacteria were observed under a scanning electron microscope. And the untreated stainless steel specimens were used as the control group.

[0063] (2) SeeFigure 5 Scanning electron microscope results, where a1 is the Streptococcus mutans adhesion result of untreated stainless steel, a2 is the Streptococcus mutans adhesion result of untreated stainless steel, a3 is the Fusobacterium nucleatum adhesion result of untreated stainless steel, b1 is the Streptococcus mutans adhesion result of the nano-stripe structure prepared in the embodiment of the present invention, b2 is the Streptococcus mutans adhesion result of untreated stainless steel, b3 is the Fusobacterium nucleatum adhesion result of untreated stainless steel. It can be seen that there is a large amount of bacteria adhesion on the untreated specimens, approaching the formation of a plaque-like structure, while the number of bacteria adhered to the stainless steel with nano-stripes after ultrafast laser treatment is significantly reduced. Additionally, from the results of the laser confocal microscope, see Figure 6 as shown, where a1 is the Streptococcus mutans adhesion result of untreated stainless steel, a2 is the Streptococcus mutans adhesion result of untreated stainless steel, a3 is the Fusobacterium nucleatum adhesion result of untreated stainless steel, b1 is the Streptococcus mutans adhesion result of the nano-stripe structure prepared in the embodiment of the present invention, b2 is the Streptococcus mutans adhesion result of untreated stainless steel, b3 is the Fusobacterium nucleatum adhesion result of untreated stainless steel. It can also be seen that on the blank stainless steel sheet stained with a live / dead bacteria stain, the number of live bacteria is significantly more than that of dead bacteria, while the number of live bacteria on the stainless steel with nano-stripes after ultrafast laser treatment is significantly reduced.

[0064] Example 4:

[0065] Verification of the biocompatibility of ultrafast laser-treated stainless steel

[0066] (1) After sterilizing the samples in Test Example 1, place them in a 24-well plate, inoculate 2×104 human gingival fibroblasts in each well, and culture them in a CO2 incubator. Use the CCK-8 method to detect cytotoxicity at 1d, 3d, and 5d respectively. Use untreated stainless steel specimens as the control group.

[0067] (2) See Figure 7 The results show that the stainless steel with nano-stripes after ultrafast laser treatment has no cytotoxicity and has good biocompatibility.

[0068] Example 5:

[0069] Animal experiment to test the antibacterial performance of stainless steel preformed crowns

[0070] (1) Process the finished stainless steel preformed crown according to the super laser parameter settings in Test Example 1. For the appearance, see Figure 8As shown, the second mandibular molars on both sides of beagle dogs were selected as experimental subjects. The left side was a stainless steel prefabricated crown without treatment, and the right side was a stainless steel prefabricated crown with nanoscale stripes after ultrafast laser treatment. Dental plaque on the crown surface was collected before crown restoration and 1, 2, and 3 months after restoration, and the number of bacteria in the plaque was detected by qPCR.

[0071] (2) See Figure 9 It can be seen that as time goes by, the amount of dental plaque on the surface of the stainless steel prefabricated crown increases, while the number of bacteria on the surface of the stainless steel prefabricated crown with nanoscale stripes after ultrafast laser treatment is lower than that of the untreated stainless steel prefabricated crown, indicating that its antibacterial effect is significantly better than that of the existing metal prefabricated crown.

[0072] In this specification, each embodiment is described in a progressive manner. The key point of each embodiment is to illustrate the differences from other embodiments. The same or similar parts among the embodiments can be referred to each other. For the device disclosed in the embodiments, since it corresponds to the method disclosed in the embodiments, the description is relatively simple, and the relevant parts can be referred to the description of the method part.

[0073] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to these embodiments shown herein, but will be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An antibacterial prefabricated metal crown, characterized in that, The antibacterial metal prefabricated crown includes a stainless steel finished prefabricated crown and silver fish-shaped nanostructures attached to the surface of the stainless steel finished prefabricated crown and distributed in a close-packed regular pattern; The silver fish-shaped nanostructures are close-packed alternating silver fish-shaped protrusions and conforming strip-shaped grooves; The width of the silver fish-shaped protrusions is 250 - 650 nanometers, the length is 1500 - 6000 nanometers, and the height is 300 - 600 nanometers; Nanoparticles are randomly and discretely distributed on the silver fish-shaped protrusions, and the size of the nanoparticles is 70 - 500 nanometers; The width of the conforming strip-shaped grooves is 200 - 450 nanometers, the length is 1500 - 6000 nanometers, and the depth is 300 - 600 nanometers.

2. The preparation method of the antibacterial metal prefabricated crown according to any one of claim 1, characterized in that, It includes the following steps: S1. Place the stainless steel finished prefabricated crown in an acetone and alcohol solution for ultrasonic cleaning to remove dust, oil stains, and fingerprints on the surface of the stainless steel finished prefabricated crown, and dry it for standby; S2. Place the stainless steel finished prefabricated crown on the focal plane of a laser processing device; S3. Use the ultrafast laser-induced ablation composite mechanism to process the stainless steel finished prefabricated crown, thereby obtaining the silver fish-shaped nanostructures distributed in a close-packed regular pattern.

3. The preparation method of the antibacterial metal prefabricated crown according to claim 2, wherein, The laser processing device in S2 is composed of an ultrafast laser, a beam expander, a 45° reflector, a scanning galvanometer, and a focusing field lens. The focal depth of the focused beam of the focusing field lens is 0 - 10 mm.

4. The preparation method of the antibacterial metal prefabricated crown according to claim 2, wherein The stainless steel finished prefabricated crown is fixed by a clamping mechanism, and the clamping mechanism is composed of a multi-axis motor and a support rod.

5. The preparation method of the antibacterial metal prefabricated crown according to claim 2, characterized in that, The ultrafast laser-induced ablation composite mechanism in S3 is mainly based on the induction mechanism to form the close-packed alternating silver fish-shaped protrusions and the conforming strip-shaped grooves; and supplemented by the ablation mechanism, the silver fish-shaped protrusion structures formed are randomly and discretely distributed with the nanoparticles.

6. The preparation method of the antibacterial metal prefabricated crown according to claim 2, wherein, The ultrafast laser is a femtosecond laser or a picosecond laser, and its wavelength is in the wavelength range of infrared light, visible light, or ultraviolet light.

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