Titanium metal dental implant and processing method thereof

Abstract

The invention discloses a titanium metal dental implant and a processing method thereof, and belongs to the technical field of medical instruments, the surface of an implant part of the implant is provided with a composite bioactive layer, and the composite bioactive layer is formed by compounding a first-stage micron hole layer formed by selective laser micro-melting and a second-stage submicron-nano mesh hole layer formed by micro-arc oxidation, and the secondary pore layer has gradient distribution of bioactive elements such as calcium and phosphorus. The processing method comprises the steps of matrix pretreatment, construction of a micron structure through selective laser micro-melting, synchronous construction of a nano structure through micro-arc oxidation, element gradient doping and post-treatment. The surface of the prepared implant has a unique micron-nano graded composite pore structure and gradient distribution of bioactive elements, the mechanical stability and the biological activity of the implant can be synergistically promoted, rapid and stable osseointegration is realized, the processing method is green and controllable, and the implant has a good application prospect.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of medical devices, in particular to a titanium dental implant and a processing method thereof. BACKGROUND

[0002] Dental implants are commonly used medical devices to replace missing tooth roots, usually made of titanium or titanium alloy with good biocompatibility. Pure titanium implant surface has low bioactivity, long bone integration period, and insufficient initial mechanical stability, which can easily lead to implant failure.

[0003] The prior art mainly uses sandblasting and acid etching, anodic oxidation and other surface treatment methods. The sandblasting and acid etching method forms macroscopic roughness by sandblasting and then forms microscopic pores by acid etching. This technology is mature, but has problems such as high environmental pressure for acid etching waste liquid treatment, high randomness of surface structure, and difficulty in controlling consistency. The anodic oxidation method can generate a porous titanium oxide coating on the titanium surface and can incorporate calcium and other elements, but the bonding strength of the coating to the substrate is sometimes insufficient, there is a risk of peeling under long-term service, and the pore structure formed is single.

[0004] There is also a single micro-arc oxidation technology in the prior art, such as the invention patent with publication number CN109371443A, which relates to a magnesium / titanium dioxide microporous ceramic coated titanium implant, which introduces calcium and phosphorus elements by micro-arc oxidation. However, the coating formed is a single-scale microporous structure, and the elements are uniformly distributed in the coating. This structure has limitations in providing mechanical interlocking force and promoting early rapid bone integration: uniform element release cannot simulate the dynamic biochemical signals required during bone healing, and single micron-sized pores also lack nanoscale bioactive topography to promote early cell adhesion and differentiation.

[0005] Based on the above, a titanium dental implant and a processing method thereof are proposed, which can provide excellent initial mechanical stability and long-term bioactivity. SUMMARY

[0006] The purpose of the present application is to provide a titanium dental implant and a processing method thereof to solve the problems in the background art.

[0007] To achieve the above-mentioned purpose, the present application provides a titanium dental implant, which comprises an implant part made of titanium or titanium alloy and an abutment connecting part connected to the implant part, the surface of the implant part is provided with a composite bioactive layer, the composite bioactive layer comprises a primary microporous layer and a secondary sub-micron-nanometer network pore layer from inside to outside; the secondary sub-micron-nanometer network pore layer is rich in bioactive elements with a content gradient decreasing from the surface layer to the inside; the bioactive elements include calcium and phosphorus elements.

[0008] Preferably, the primary micron-sized pore layer consists of multiple hemispherical pits with a pore size of 10-50 μm and a depth of 5-25 μm, and the hemispherical pits are arranged in a regular array or biomimetic random distribution.

[0009] Preferably, the secondary submicron-nano mesh pore layer is an interconnected mesh pore layer with a pore size of 100~800nm ​​and a layer thickness of 3~10μm.

[0010] Preferably, the atomic ratio of calcium to phosphorus on the outermost surface of the secondary submicron-nano mesh pore layer is 1.5 to 1.8.

[0011] Preferably, the bioactive element also includes one or two of silicon and strontium, which can further enhance its bioactivity.

[0012] The present invention also provides a method for processing the above-mentioned titanium dental implant, comprising the following steps: S1. Use precision machining to process titanium or titanium alloy implant blanks. The blanks include the implant part and the abutment connection part. Polish the blanks, then ultrasonically clean them with acetone and anhydrous ethanol in sequence, rinse them with deionized water and dry them. S2. A pulsed laser is used to perform selective micro-melting on the implantation part surface of the implant blank, forming a primary micron-pore layer that is mechanically interlocked with the implantation part substrate under argon protection. S3. The implant blank treated in step S2 is placed in an electrolyte as the anode and a stainless steel tank as the cathode to perform micro-arc oxidation treatment, simultaneously forming a secondary submicron-nano mesh pore layer and doping with calcium and phosphorus elements. S4. The implant blank after micro-arc oxidation is ultrasonically cleaned and dried with deionized water to obtain the target titanium dental implant.

[0013] Preferably, in step S2, the wavelength of the pulsed laser is 1064 nm, the width is 10~100 ns, the single pulse energy is 0.5~3 mJ, and the scanning speed is 100~1000 mm / s.

[0014] Preferably, in step S3, the electrolyte has a pH of 9-12, a temperature of 20-30°C, and contains 0.05-0.2 mol / L of water-soluble calcium salt and 0.02-0.1 mol / L of water-soluble phosphate. The water-soluble calcium salt is calcium acetate, calcium nitrate, or calcium chloride; the water-soluble phosphate is sodium dihydrogen phosphate or disodium hydrogen phosphate.

[0015] Preferably, in step S3, the micro-arc oxidation uses a bipolar pulse power supply with a final output voltage of 300~450V, a boost rate of 2~10V / s, a frequency of 500~1000Hz, a duty cycle of 20~40%, and a processing time of 5~15min.

[0016] Preferably, in S1 and S4, the ultrasonic cleaning time using acetone, anhydrous ethanol, and deionized water is 10-15 minutes, and the drying temperature is 80-100℃.

[0017] The hierarchical porous structure and elemental gradient doping achieved in the processing method of this invention are based on the following well-known scientific principles and technological laws: In step S2, laser ablation forms micron-sized pits. When a nanosecond pulsed laser (wavelength 1064nm) is focused on the titanium surface, its energy is absorbed by the material in a very short time, causing selective melting and vaporization in the irradiated area. The material is removed to form pits. The size (aperture and depth) of the pits is directly controlled by the laser energy density, spot diameter and pulse width, and its spatial distribution is determined by the precise programming of the scanning path. This is a mature technology in the field of laser material processing. In step S3, micro-arc oxidation forms a nanoporous layer and element doping. Using titanium as the anode, during micro-arc oxidation in an alkaline electrolyte containing active ions such as calcium and phosphorus, the applied high-voltage pulse will induce a discharge micro-arc on the workpiece surface. The high-temperature and high-pressure plasma environment generated by the micro-arc promotes plasma electrochemical oxidation of the titanium substrate, resulting in the in-situ growth of a titanium oxide ceramic layer. On the other hand, it drives calcium ions, phosphate ions, etc. in the electrolyte to migrate to the discharge channel and be incorporated into the growing ceramic layer. Furthermore, the formation mechanism of the elemental gradient distribution is as follows: During constant-pressure micro-arc oxidation, the coating grows outward from the substrate. The newly formed coating front (near the electrolyte interface) has the highest ion capture efficiency, while in the early-formed interior of the coating, ions are limited by diffusion and cannot penetrate deeply. Therefore, the incorporated elements such as calcium and phosphorus naturally form a gradient distribution with their content gradually decreasing from the coating surface to the interior. This phenomenon is an inherent characteristic of the micro-arc oxidation process and can be quantitatively characterized by X-ray photoelectron spectroscopy (XPS) depth profiling.

[0018] Therefore, the titanium dental implant and its processing method of the present invention have the following beneficial effects: (1) The array of micron-sized pits pre-constructed by laser and combined with the metallurgical matrix provides a strong mechanical interlocking anchor point for bone tissue; the superimposed nanoscale roughness formed by micro-arc oxidation works synergistically to enable the implant to obtain an initial mechanical locking force far exceeding that of traditional roughened surfaces after implantation, effectively resisting micro-movement and creating a stable mechanical environment for bone integration.

[0019] (2) The gradient distribution of calcium and phosphorus elements inevitably generated by the micro-arc oxidation process, and the calcium-to-phosphorus atomic ratio of 1.5 to 1.8 achieved through precise control on the outermost surface, give the implant surface both "long-lasting ion release" and "optimal surface chemistry" as dual biological activities. This not only continuously simulates and promotes the chemical and biological processes of bone healing and induces rapid deposition of bone-like apatite, but also forms strong chemical bonds with osteoblasts, thereby significantly shortening the bone integration cycle and fundamentally improving the bonding strength.

[0020] (3) The entire process (laser micro-melting + micro-arc oxidation) is free from strong acid and strong alkali etching, with less wastewater discharge and environmental friendliness. By precisely controlling the process parameters, the high consistency and repeatability of the product surface structure and composition are ensured, making it very suitable for large-scale production.

[0021] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the structure of Embodiment 1 of the present invention; Figure 2 This is a cross-sectional schematic diagram of the composite bioactive layer in Embodiment 1 of the present invention; Figure label: 1. Implantation site; 2. Abutment connection site; 3. Primary micron-pore layer; 4. Secondary submicron-nano mesh pore layer. Detailed Implementation

[0023] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0024] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments.

[0025] Example 1 like Figure 1 , Figure 2 As shown, this embodiment provides a titanium dental implant, including an implant portion 1 made of titanium or titanium alloy and an abutment connection portion 2 connected to the implant portion 1. The surface of the implant portion is provided with a composite bioactive layer, which, from the inside out, includes a primary micron-pore layer 3 and a secondary submicron-nano mesh pore layer 4. The titanium or titanium alloy is medical-grade pure titanium or medical-grade titanium alloy. This embodiment also provides a titanium dental implant with calcium-phosphorus gradient doping, and the specific processing steps are as follows: S1. Substrate Processing and Pretreatment: Medical-grade titanium alloy rods were selected and machined into standard dental implant blanks (implant diameter 4.5mm, length 10mm) using a precision CNC lathe. The implant portion 1 of the implant blank was sequentially hand-polished using 400#, 800#, 1500#, and 3000# silicon carbide sandpaper until the surface roughness Ra ≤ 0.8μm (measured using a surface roughness meter). After polishing, the implant blank was placed in acetone and anhydrous ethanol, and ultrasonically cleaned for 15 minutes each time to thoroughly remove surface grease and impurities. It was then rinsed three times with deionized water for 3 minutes each time. Finally, the cleaned implant was placed in a forced-air drying oven and dried at 90℃ for 3 hours.

[0026] S2. Laser-selective micro-melting preparation of the first-level micro-pore layer 3: The pretreated implant was fixed on a three-dimensional moving platform. A pulsed fiber laser (wavelength 1064nm) was used to scan and process the surface of the implantation area under an argon protective atmosphere (flow rate 6L / min, purity ≥99.99%). The laser parameters were set as follows: pulse width 50ns, single pulse energy 1.8mJ, scanning speed 500mm / s, and spot diameter approximately 20μm. A linear reciprocating scanning path was used, with both row and column spacing set to 40μm.

[0027] Based on the principle of laser ablation, the energy density mentioned above is much higher than the ablation threshold of titanium. Therefore, after this treatment, a regular hemispherical array of pits can be formed on the implant surface. According to the well-known principle of laser-material interaction and the well-known correspondence between laser energy density and ablation pit size, by using the above parameter combination, it is expected that a regular hemispherical array of pits can be formed on the implant surface, with a pit diameter of approximately 30 μm and a depth of approximately 15 μm.

[0028] Preparation and elemental gradient doping of S3 and secondary submicron-nano mesh porous layer 4 by micro-arc oxidation: First, the micro-arc oxidation electrolyte was prepared by dissolving calcium nitrate and disodium hydrogen phosphate in deionized water and stirring until completely dissolved, resulting in a solution containing 0.12 mol / L calcium nitrate and 0.06 mol / L disodium hydrogen phosphate. The pH of the electrolyte was adjusted to 10.5 using sodium hydroxide solution. The electrolyte was then poured into a stainless steel tank, and a water bath circulation system was used to maintain the liquid temperature at 25±2℃.

[0029] Using the implant treated in step S2 as the working anode and a stainless steel tank as the cathode, the electrode spacing was adjusted to 7 cm. A bipolar pulsed power supply was used for micro-arc oxidation. The process involved progressively increasing the voltage from 0 V to a final voltage of 400 V at a rate of 5 V / s and maintaining this voltage. Other electrical parameters were: frequency 800 Hz, positive pulse duty cycle 22%, and negative pulse duty cycle 8%. The total treatment time was 10 minutes.

[0030] Based on the micro-arc oxidation film formation mechanism, using the electrolyte and electrical parameters of S3 mentioned above, it is expected that a ceramic layer with a thickness of approximately 6 μm can be grown in situ, covering the surface and inner walls of the micron-sized pits. This layer is expected to have an interconnected submicron-nanoscale network pore structure, with a typical pore size range expected to be between 300-600 nm.

[0031] Based on the ion doping and diffusion mechanism of micro-arc oxidation, calcium (Ca) and phosphorus (P) are expected to exhibit a gradient distribution in this secondary porous layer, with the content decreasing continuously from the outermost surface to the interior. XPS analysis of the outermost surface (<10 nm) yielded an expected calcium-to-phosphorus atomic ratio of approximately 1.65.

[0032] S4. Post-treatment: Immediately after micro-arc oxidation, the implant is removed from the electrolyte and placed in a beaker containing fresh deionized water. It is then ultrasonically cleaned at 40°C for 12 minutes to remove any remaining electrolyte residue. After cleaning, the implant is dried in a 90°C oven for 3 hours to obtain the titanium dental implant of this embodiment.

[0033] Example 2 This embodiment provides a titanium dental implant with silicon, calcium, and phosphorus composite gradient doping, and the specific processing method is as follows: S1. Matrix processing and pretreatment: Medical titanium alloy rods are selected, and the processing and pretreatment steps are the same as in Example 1.

[0034] S2. Laser selective micro-melting preparation of the primary micron-pore layer 3: The basic parameters of laser processing are the same as in Example 1, but the scanning path is changed to a "bionic random distribution" path generated based on a fractal algorithm to simulate the irregular porous structure of natural bone. It is expected that this step will form a micron-pitted layer with pore size and depth varying within a certain range (e.g., 20-45 μm) and a distribution more closely resembling that of natural bone.

[0035] Preparation of S3 and secondary submicron-nano mesh porous layer 4 by micro-arc oxidation and elemental composite gradient doping: First, the electrolyte was prepared by adding sodium silicate to the electrolyte of Example 1 to achieve a concentration of 0.03 mol / L. The final electrolyte composition was: 0.15 mol / L calcium chloride, 0.08 mol / L sodium dihydrogen phosphate, and 0.03 mol / L sodium silicate. The pH was adjusted to 11.0 with NaOH.

[0036] The micro-arc oxidation process parameters were adjusted as follows: final voltage 420V, boost rate 8V / s, frequency 900Hz, positive pulse duty cycle 25%, negative pulse duty cycle 7%, and processing time 12 minutes.

[0037] This step involves incorporating silicon (Si) into the coating in a gradient manner while simultaneously forming a calcium-phosphorus gradient-doped nanoporous layer.

[0038] S4. Post-processing: Same as in Example 1.

[0039] In this embodiment, elements with clear biological functions, such as silicon (Si) and strontium (Sr), are introduced and their synchronous gradient distribution with calcium and phosphorus is achieved. This allows for the customization of the biological performance of implants for specific needs (such as osteoporosis), ensuring a high success rate for long-term implantation.

[0040] Comparative Example 1 This comparative example uses the traditional sandblasting and acid etching method. The same TC4 titanium alloy implant blank as in Example 1 is selected. After the same pretreatment in S1, no laser processing is performed. Instead, the product is directly treated with the industry-standard sandblasting (alumina sand particles, particle size 250~500μm) followed by acid etching (concentrated hydrochloric acid / concentrated sulfuric acid mixture, 60℃, 30min). The subsequent cleaning and drying steps are the same as in S4 to obtain the product.

[0041] This sandblasting and acid etching process is a well-known technology in the industry. According to its principle, the resulting sample surface is expected to have a randomly distributed, multi-scale mixed rough morphology, which does not possess the regular or biomimetic micron-shaped pit array pre-constructed by laser in Embodiment 1 of this invention. At the same time, its surface does not contain the calcium and phosphorus element gradient doping layer introduced by the micro-arc oxidation process.

[0042] Based on the above-mentioned process principles and the expected differences in structure and composition, and combined with well-known research conclusions in the field of osseointegration (i.e., regular / biomimetic micron structures provide better mechanical anchoring; calcium-phosphorus gradients and specific atomic ratios significantly enhance bioactivity and bone induction capacity), it can be reasonably expected that the implant provided in Example 1 of this invention will be significantly superior to the traditional sandblasting and acid etching products represented by Comparative Example 1 in terms of bone integration speed, integration strength and long-term stability.

[0043] Therefore, the present invention provides a titanium dental implant and its processing method, which obtains a composite structure of hierarchical porous and gradient chemistry, which can synergistically promote the mechanical stability and bioactivity of the implant, and achieve rapid and stable osseointegration. Its processing method is green and controllable, and has good application prospects.

[0044] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. 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 still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A titanium dental implant, comprising an implant portion made of titanium or titanium alloy and an abutment connection portion, characterized in that: The implanted part has a composite bioactive layer on its surface, which includes a primary micron-pore layer and a secondary submicron-nano mesh pore layer from the inside to the outside. The secondary submicron-nano mesh pore layer is enriched with bioactive elements whose content decreases from the surface to the inside. The bioactive elements include calcium and phosphorus.

2. The titanium dental implant according to claim 1, characterized in that: The primary micron-pore layer consists of multiple hemispherical pits with a pore size of 10-50 μm and a depth of 5-25 μm.

3. The titanium dental implant according to claim 1, characterized in that: The secondary submicron-nano mesh pore layer is an interconnected mesh pore layer with a pore size of 100~800nm ​​and a layer thickness of 3~10μm.

4. A titanium dental implant according to claim 1, characterized in that: The atomic ratio of calcium to phosphorus on the outermost surface of the secondary submicron-nano mesh pore layer is 1.5 to 1.

8.

5. A titanium dental implant according to claim 1, characterized in that: The bioactive elements also include one or two of silicon and strontium.

6. A method for processing a titanium dental implant as described in any one of claims 1-5, characterized in that, Includes the following steps: S1. Use precision machining to process titanium or titanium alloy implant blanks. The blanks include the implant part and the abutment connection part. Polish the blanks, then ultrasonically clean them with acetone and anhydrous ethanol in sequence, rinse them with deionized water and dry them. S2. A pulsed laser is used to perform selective micro-melting on the implantation part surface of the implant blank, forming a primary micron-pore layer that is mechanically interlocked with the implantation part substrate under argon protection. S3. The implant blank treated in step S2 is placed in an electrolyte as the anode and a stainless steel tank as the cathode to perform micro-arc oxidation treatment, simultaneously forming a secondary submicron-nano mesh pore layer and doping with calcium and phosphorus elements. S4. The implant blank after micro-arc oxidation is ultrasonically cleaned and dried with deionized water to obtain the target titanium metal dental implant.

7. The processing method according to claim 6, characterized in that: In S2, the wavelength of the pulsed laser is 1064nm, the width is 10~100ns, the single pulse energy is 0.5~3mJ, and the scanning speed is 100~1000mm / s.

8. The processing method according to claim 6, characterized in that: In step S3, the electrolyte has a pH of 9-12 and a temperature of 20-30°C. The electrolyte contains 0.05-0.2 mol / L of water-soluble calcium salt and 0.02-0.1 mol / L of water-soluble phosphate.

9. The processing method according to claim 6, characterized in that: In step S3, the micro-arc oxidation uses a bipolar pulse power supply with a final output voltage of 300~450V, a boost rate of 2~10V / s, a frequency of 500~1000Hz, a duty cycle of 20~40%, and a processing time of 5~15min.

10. The processing method according to claim 6, characterized in that: In S1 and S4, the ultrasonic cleaning time using acetone, anhydrous ethanol, and deionized water is 10-15 minutes, and the drying temperature is 80-100℃.

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