One-stage silicon nitride implant

Abstract

The invention discloses a one-section type silicon nitride implant and belongs to the technical field of oral medicine. The one-section type silicon nitride implant comprises an abutment, a neck part and a root part which are integrally formed by adopting an injection process, a conical external thread is at least arranged at the root, and at least part of the conical external thread is cut off by a cutting groove; the implant is sequentially provided with a first thread, a second thread and a third thread from the root part to the neck part, the first thread and the second thread are arranged at the root part, and the third thread is arranged at the neck part. The invention can solve the problems that the silicon nitride implant is poor in machinability and cannot be used for manufacturing reliable dental implants with high mechanical properties.

Description

Technical Field

[0001] The invention relates to a one-stage silicon nitride implant, belonging to the technical field of oral medicine. Background Art

[0002] As an important technology in modern stomatology, dental implants have become one of the main means to solve the problem of missing teeth. The core principle is to accurately implant artificial roots into the upper / lower jaws of the edentulous area. After a period of bone integration, the artificial roots form a close connection with the surrounding bone tissue. Then, the base is installed through connectors such as screws to firmly support the crown part above. With the help of complete imaging data and advanced digital processing technology, highly personalized crowns can be obtained, which together with the base and artificial roots form a complete implant. This technology not only restores the chewing function of teeth, but also greatly improves the aesthetics and voice function, becoming the preferred treatment option for many patients.

[0003] At present, the materials of artificial tooth roots and abutments in the domestic market are pure titanium or titanium alloy, and the materials of crowns on abutments are mostly zirconia ceramics, while artificial tooth roots made of zirconia ceramics have also appeared in the international market. However, existing implants still have the following defects:

[0004] ① Lack of antibacterial properties; the oral cavity is a complex microbial environment, and implants are easily invaded by bacteria after implantation, leading to peri-implantitis, which in turn leads to the absorption of bone tissue around the implant, and complications such as hindering bone integration, affecting the effect of the operation and the life of the implant. Although titanium alloys have good biocompatibility, titanium alloys themselves do not have antibacterial properties, and the biological inertness of their surface makes it relatively easy for bacteria to attach and form plaque biofilms, which greatly increases the risk and degree of infection and the difficulty of antibacterial treatment. Although the surface of titanium alloy implants can be modified to enhance their antibacterial effects, the effects of these treatments are not ideal and are not long-lasting;

[0005] ②Poor bone integration performance: The strength of the combination between the implant and the bone tissue directly affects the service life and success rate of the implant. Whether the implant can form stable bone integration is the key to its success. The existing implant healing time is long, which affects the patient's recovery speed.

[0006] The latest research shows that non-oxide ceramics - silicon nitride ceramics, in addition to the advantages of general ceramics, are also biosafe and chemically stable. For dental implants, silicon nitride ceramics, known as the "all-around champion in the ceramic world," is a potential, excellent, and upgraded raw material choice. According to public information, there are currently no approved silicon nitride ceramic dental implants in the domestic and foreign markets. There are still many problems to be solved in the design and manufacturing of dental implants made of silicon nitride. The most typical problem is how to achieve the best balance in the field of dental implants among the three aspects of silicon nitride ceramic material formulation, processing and molding, sintering preparation technology, and comprehensive product performance. For example, as the final product, the implant needs to be implanted in the jawbone, so the product needs to have a special thread that is self-tapping and does not damage the bone too much. This special thread needs to be customized. Ceramics such as silicon nitride have a much higher hardness than ordinary metal materials and belong to the precision processing of superhard materials. The difficulty and cost of this type of processing are very high, so other processing and molding technologies must be considered. At the same time, it is very important to use a certain specific processing and molding method, and its impact on the performance of the final product must be minimized. As ceramics that need to be sintered after processing and molding, their formula is involved. In order to improve the sintering preparation process, corresponding additives need to be added. Because the final product is a medical device that needs to be implanted in the human body, additives cannot be selected arbitrarily. A series of requirements such as safety and effectiveness need to be met. In summary, for dental implants, based on customized silicon nitride ceramic material formulas, with the help of special ceramic preparation processes, combined with targeted dental implant product design, the combination, optimization and balance of these three aspects are the target solution. Summary of the invention

[0007] In view of the above-mentioned deficiencies in the prior art, the present invention proposes a one-piece silicon nitride implant, which can solve the problem that the silicon nitride implant has poor machinability and cannot be used to manufacture reliable dental implants with high mechanical properties.

[0008] The present invention relates to a one-piece silicon nitride implant, comprising a base, a neck and a root integrally formed by a ceramic injection process;

[0009] The implant is provided with a first thread, a second thread and a third thread in sequence from the root to the neck, the first thread and the second thread are arranged at the root, and the third thread is arranged at the neck;

[0010] The first threaded area is provided with 2 to 4 cutting grooves.

[0011] For some specific embodiments, the first thread is a conical external thread, and the second thread and the third thread are cylindrical external threads.

[0012] For some specific embodiments, the root is provided with a porous layer on the surface, and the porosity of the porous layer ranges from 35% to 75%.

[0013] Preferably, the cone angle of the conical external thread area is 10° to 15°; further preferably, the angle between the groove and the implant axis is half of the cone angle, and the groove width is 1 to 2 mm, aiming to reduce implantation pressure, improve self-tapping and bone chip accumulation, and improve implantation efficiency.

[0014] Preferably, the thread profile of the first thread is a sawtooth thread, the radius of the top arc is 0.1-0.2 mm, the radius of the bottom transition arc is 0.4-0.5 mm, the pitch is 0.6-1.0 mm, the thread depth is 0.6-1.0 mm, the thread length is 0.35L-0.4L, and L is the total length of the root and the neck;

[0015] Preferably, the thread profile of the second thread is a trapezoidal thread, the crest width is 0.2-0.4 mm, the radius of the transition arc at the bottom is 0.4-0.5 mm, the pitch is 0.6-1.0 mm, the thread depth is 0.2-1.0 mm, the thread length is 0.4L-0.45L, and L is the total length of the root and the neck;

[0016] Preferably, the thread profile of the third thread is a triangular thread, the top arc radius is 0.1-0.2mm, the bottom transition arc radius is 0.4-0.5mm, the pitch is 0.2-0.4mm, the thread depth is 0.02-0.5mm, the thread length is 0.15L-0.25L, and L is the total length of the root and neck.

[0017] For some specific implementation schemes, the axial length of the abutment is 3 to 6 mm.

[0018] Compared with the prior art, the present invention has the following technical effects:

[0019] 1) Compared with titanium alloy, zirconium oxide and other materials, silicon nitride has excellent antibacterial properties, bone integration ability and mechanical properties;

[0020] 2) Compared with implants made by 3D printing and light-curing technology, implants made by ceramic injection molding are more compact in structure, ensuring the excellent mechanical properties of the final implants;

[0021] 3) The abutment, neck and root are integrally formed, avoiding secondary processing; in particular, the independent manufacturing of the abutment and other parts of the implant results in the inability to form the inner hole connection structure, and the connection strength is less than the strength of the silicon nitride material itself. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1Schematic diagram of the overall structure of the one-stage silicon nitride implant in Examples 1 to 4. DETAILED DESCRIPTION

[0023] The present invention is described in detail below in conjunction with specific embodiments. Experimental methods without specific conditions in the examples are carried out according to conventional methods and conditions.

[0024] The one-piece implants involved in the embodiments and comparative examples of the present invention need to undergo the following performance tests.

[0025] The density test shall be carried out in accordance with GB / T 25995-2010 Test method for density and apparent porosity of fine ceramics.

[0026] The hardness test is carried out in accordance with GB / T 16534-2009 Fine Ceramics Room Temperature Hardness Test Method.

[0027] The compressive strength test is carried out in accordance with "GB / T 8489-2006 Fine Ceramics Compression Strength Test Method".

[0028] The fracture toughness test is carried out in accordance with ISO 14627:2012 Fine ceramics (advanced ceramics, advanced technical ceramics)-Resistance of silicon nitride materials for rolling bearing balls to fracture at room temperature by the indentationfracture (IF) method.

[0029] Regarding the antibacterial rate, the detection method and operation steps are as follows:

[0030] Porphyromonas gingivalis, Staphylococcus aureus and Escherichia coli were inoculated on a slant of a nutrient agar medium, cultured at 37±1°C for 24 hours, and then stored at 0-5°C (no longer than 1 month) as slant-preserved bacteria;

[0031] Transfer the slant-preserved bacteria to the plate nutrient agar medium and culture at 37±1℃ for 24 hours, once a day for no more than 2 weeks. The test should use fresh bacterial culture after 2 consecutive transfers (transferred within 24 hours);

[0032] Use an inoculation loop to take a small amount (scrape 1-2 loops) of fresh bacteria from the culture medium, add it to the culture medium, and make 10-fold incremental dilutions in sequence. Count the cells using a cell counting plate and select a bacterial solution concentration of 10.0×10 5The dilution with cfu / ml was used as bacterial solution for experimental detection;

[0033] Prepare 15 φ90mm sterile plates, place 5-6 φ90mm sterile filter papers on the bottom of the plates, and pour in an appropriate amount of sterile purified water to allow the filter paper to fully absorb water. It is best if no large amount of water precipitates when pressing the filter paper with sterile tweezers;

[0034] Take 15 sterile filter membranes with a size of φ0.24μm×50mm, cover them on the sterile filter paper of each plate, and spread them flat. Take 0.2ml of the experimental bacterial solution and drop it on the sterile filter membrane with a size of φ0.24μm×50mm;

[0035] Use sterile tweezers to pick up the negative control sample (A), blank control sample (B), and test sample (C). Prepare 5 parallel samples for each sample and cover them on a φ0.24μm×50mm sterile filter membrane to make the bacterial solution evenly contact the sample. Incubate at 37±1℃ for 24h.

[0036] Take out the samples that have been cultured for 24 hours, add 20 ml of eluent respectively, wash sample A, sample B, sample C and the covering film repeatedly, and shake well. Use a sterilized pipette tip to draw 1 ml of the eluent stock solution and transfer it to a sterile culture dish, inject about 15 ml of nutrient agar medium into the culture dish, and rotate the culture dish to mix evenly. Repeat the flat plate operation twice to obtain 2 culture dishes with elution stock solution. Take another 1 ml of the eluent stock solution and slowly inject it into a test tube containing 9 ml of sterile saline along the wall of the tube. The tip of the pipette tip does not touch the diluent in the tube. Shake the test tube, mix evenly, and make a 1:10 elution dilution solution;

[0037] Take 1 ml of 1:10 elution diluent and transfer it to a sterile culture dish. Inject about 15 ml of nutrient agar medium into the culture dish and rotate the culture dish to mix evenly. Repeat the plate-laying operation twice to obtain two 1:10 elution diluent culture dishes. Take 1 ml of 1:10 elution diluent and slowly inject it into a test tube containing 9 ml of sterile saline along the tube wall. The tip of the gun does not touch the diluent in the tube. Shake the test tube to mix evenly to make a 1:100 elution diluent.

[0038] Take 1 ml of 1:100 elution diluent and transfer it to a sterile culture dish. Inject about 15 ml of nutrient agar medium into the culture dish and rotate the culture dish to mix evenly. Repeat the plate-laying operation twice to obtain two 1:100 elution diluent culture dishes. Take 1 ml of 1:100 elution diluent and slowly inject it into a test tube containing 9 ml of sterile saline along the tube wall. The tip of the gun does not touch the diluent in the tube. Shake the test tube to mix evenly to make a 1:1000 elution diluent.

[0039] Take 1 ml of 1:1000 elution dilution and transfer it to a sterile culture dish. Pour about 15 ml of nutrient agar medium into the culture dish and rotate the culture dish to mix evenly. Repeat the plating operation twice to obtain 2 1:1000 elution dilution culture dishes.

[0040] When counting the colonies on the plates, you can observe with your naked eyes and use a magnifying glass if necessary to prevent omissions. After recording the number of colonies on each plate, calculate the average total number of colonies on each plate with the same dilution. Select plates with a colony count between 30 and 300 as the standard for determining the total number of colonies;

[0041] If two plates are used for one dilution, the average of the two plates should be used. If one of the plates has large flake colonies growing, it should not be used. Instead, the plate without flake colonies should be used as the colony count for that dilution. If the flake colonies are less than half of the plate, and the colonies in the remaining half are evenly distributed, half of the plate can be counted and multiplied by 2 to represent the colony count of the whole plate. If there are chain colonies growing in the plate, if there is only one chain, it can be regarded as one colony; if there are several chains from different sources, each chain should be counted as a colony. A dilution with an average colony count between 30 and 300 should be selected and reported by multiplying it by the dilution multiple. If there are two dilutions, and the number of colonies grown is between 30 and 300, the decision will be made based on the ratio between the two. If the ratio is less than or equal to 2, the average should be reported; if it is greater than 2, the smaller number should be reported. If the average colony count of all dilutions is greater than 300, the average colony count of the highest dilution multiplied by the dilution multiple should be reported. If the average colony counts of all dilutions are less than 30, the average colony count of the lowest dilution multiplied by the dilution factor should be reported. If no colonies grow at all dilutions, report as less than 1 multiplied by the lowest dilution factor. If the average colony counts of all dilutions are not between 30 and 300, and some of them are greater than 300 or less than 30, report as the average colony count closest to 30 or 300 multiplied by the dilution factor;

[0042] When the colony count is less than 100, it is reported as the actual number. When it is greater than 100, two significant figures are used, and the values ​​after the two significant figures are rounded off. In order to shorten the zeros after the number, it can also be expressed as an exponent of 10;

[0043] The viable count result was multiplied by 100 to obtain the actual viable counts recovered from sample A, sample B, and sample C after 24 hours of culture, which are A, B, and C, respectively;

[0044] Ensure that the experimental results meet the following requirements, otherwise the test is invalid:

[0045] The five parallel viable bacteria values ​​of the same blank control sample B must meet the requirement of (highest logarithm value - lowest logarithm value) / average viable bacteria value logarithm value not greater than 0.3;

[0046] The actual recovered viable bacteria value A of sample A should not be less than 1.0×10 5 cfu / piece, and the actual recovered viable bacteria value B of sample B should not be less than 1.0×10 4 cfu / piece;

[0047] The antibacterial rate is calculated according to the following formula:

[0048] R = (BC) / B × 100%;

[0049] Where:

[0050] R——antibacterial rate (%);

[0051] B——Average number of recovered bacteria in blank control samples, cfu / piece;

[0052] C——Average number of recovered bacteria in antibacterial samples, cfu / tablet.

[0053] Regarding bone integration, the detection method and operation steps are as follows:

[0054] Corresponding to Example 1 and Examples 1 to 4, a cylindrical sample rod with a diameter of 2 mm and a height of 6 mm was prepared according to the same material and the same process. According to the requirements of "GB / T 16886.6-2022 Biological Evaluation of Medical Devices Part 6: Local Reaction Test after Implantation", the sample rod was implanted into the femur of a New Zealand white rabbit through a bone drill, and the fascia and skin incisions were sutured with medical sutures. Antibiotics were used for anti-inflammatory treatment for three days after surgery. The animals were euthanized 4 weeks after implantation, the implantation site was observed with the naked eye, and enough unaffected tissue including the implanted sample rod and the surrounding area was cut and fixed in a 10% formaldehyde solution for not less than 48 hours. After fixation, the tissue including the implantation point was dehydrated, decalcified, embedded, and HE stained for pathological analysis. The stained tissue slices were placed under an optical microscope to observe the tissue reaction around the implant site. The degree of tissue reaction was determined based on the measurement of the distance from the implant / tissue interface to the unaffected area with normal tissue and vascular characteristics, including the thickness of the fibrous cyst, the number and type of inflammatory cells, and other abnormalities at the implant rod-tissue interface.

[0055] The structure of the one-stage silicon nitride implant in Examples 1 to 4 is as follows: Figure 1 As shown. The one-piece silicon nitride implant includes an integrally formed abutment, a neck and a root;

[0056] The implant is provided with a first thread, a second thread and a third thread in sequence from the root to the neck, the first thread and the second thread are arranged at the root, and the third thread is arranged at the neck;

[0057] The first thread is a conical external thread, and the first thread region is provided with grooves, the number of the grooves being 3;

[0058] The second thread and the third thread are cylindrical external threads;

[0059] The first threaded area and the second threaded area are provided with a porous layer on the surface, and the porosity of the porous layer is set to 60%.

[0060] The cone angle α of the tapered external thread area is 10°, the groove angle is half of the cone angle, and the groove width is 2 mm.

[0061] The thread profile of the first thread is a sawtooth thread, the radius of the top arc is 0.1 mm, the radius of the bottom transition arc is 0.4 mm, the pitch is 0.6 mm, the thread depth is 0.6 mm, and the thread length L1 is 0.35L, where L is the total length of the root and the neck;

[0062] The thread profile of the second thread is a trapezoidal thread, the crest width is 0.2 mm, the radius of the transition arc at the bottom is 0.4 mm, the pitch is 1.0 mm, the thread depth is 0.6 mm, and the thread length L2 is 0.45L;

[0063] The thread profile of the third thread is a triangular thread, the top arc radius is 0.1mm, the bottom transition arc radius is 0.4mm, the pitch is 0.2-0.4mm, the thread depth is 0.1mm, the thread length L3 is 0.2L; the neck diameter D is set to 10mm.

[0064] The axial length L4 of the base is 5 mm.

[0065] Example 1

[0066] The process of preparing the silicon nitride dental implant assembly in this embodiment is as follows.

[0067] Feed preparation steps

[0068] S1, weigh 425g silicon nitride powder, 10g zirconium oxide and 30g magnesium oxide, add them into the vacuum ball mill of the vacuum planetary mixer, and ball mill them at a speed of 300r / min for 12h to obtain ball milling slurry; the vacuum ball mill adopts nylon lining, the grinding medium is 99.95% high-purity silicon nitride microbeads with a diameter of 0.5mm, and the solvent is anhydrous ethanol; if anhydrous ethanol is used as the solvent, the vacuum ball mill needs to be evacuated and nitrogen is introduced before ball milling, and the operation is repeated until there is no oxygen residue in the vacuum ball mill, and the operation is generally repeated 3 to 5 times;

[0069] S2, using a pressure spray granulator to spray granulate the ball mill slurry to obtain granulated powder; the inlet temperature of the dryer in the pressure spray granulator is 50°C, the outlet temperature is 30°C, the pressure difference of the cyclone separator is 200Pa, the inner diameter of the nozzle center hole and its wall thickness are both 0.16 mm, the pressure is 2.0MPa, the jet angle range of the ceramic spiral nozzle is 60°, the feed rate is 50mL / min, and the powder after spray drying is classified by a vibrating screen separator, thereby obtaining granulated powder with an average diameter of 0.9 microns;

[0070] S3, add 465g granulation powder, 15g polypropylene, 10g polyvinyl pyrrolidone and 10g polytetrafluoroethylene into the mixing chamber of the vacuum mixer, the mixing temperature is 100°C, the mixing time is 4h, and the feed is obtained; before mixing, vacuumization and nitrogen are required, and the operation is repeated until there is no oxygen residual in the mixing chamber.

[0071] Injection molding steps

[0072] The prepared feed material is injection molded and sent to an injection molding machine for injection; the melt is injected into a mold with a temperature of 100°C under high pressure, the injection pressure is 80MPa, the injection temperature is 160°C, the injection speed is 10mm / s, filled into the mold cavity, the pressure is maintained for 3 minutes, and then cooled to room temperature to form a silicon nitride crown blank and a one-piece silicon nitride implant blank, respectively.

[0073] Laser Etching Steps

[0074] Laser etching is performed on the portion of the one-piece silicon nitride implant blank corresponding to the root of the finished product, and the scanning interval of the laser etching is 0.5 mm.

[0075] Steps for preparing finishing layer slurry

[0076] Weigh 32g of kaolin, 25g of palygorskite, 15g of quartz, 10g of potassium feldspar, 6g of calcite, 5g of titanium dioxide, 4g of yttrium oxide, 2g of zirconium oxide and 1g of silicon nitride, add them into a vacuum ball mill (with nylon lining) of a vacuum planetary mixer in the ratio of 1:1.5:2, mix and ball mill at a speed of 300r / min for 30h to obtain a finishing layer slurry.

[0077] Thermal degreasing steps

[0078] The laser-etched one-piece silicon nitride implant blank and the silicon nitride crown blank were placed in a flowing inert gas atmosphere, heated to 400°C at a heating rate of 10°C / min, and the sintering time was 2h.

[0079] Surface preparation steps

[0080] The silicon nitride crown blank that has undergone the thermal degreasing step is immersed in the finishing layer slurry. After 2 minutes of soaking, it is taken out and dried naturally.

[0081] Sintering steps

[0082] The silicon nitride implant blank that has undergone the thermal degreasing step and the silicon nitride crown blank that has been impregnated with the finishing layer slurry are placed in a flowing inert gas atmosphere for three-stage sintering; in the first stage, they are heated to a sintering temperature of 1000°C at a heating rate of 10°C / min, and the sintering time is 2h; in the second stage, they are heated to a sintering temperature of 1400°C at a heating rate of 8°C / min, and the sintering time is 2h; in the third stage, they are gas-pressure sintered, the inert gas pressure is increased from normal pressure to 3MPa, and heated to a sintering temperature of 1900°C at a heating rate of 5°C / min, and the sintering time is 2h, to obtain a dental implant assembly consisting of a silicon nitride implant and a silicon nitride crown.

[0083] Example 2

[0084] The difference from Example 1 is that the weight of silicon nitride is adjusted to 440 g.

[0085] Example 3

[0086] The difference from Example 1 is that the weight of zirconium oxide was adjusted to 30 g and the weight of magnesium oxide was adjusted to 10 g.

[0087] Example 4

[0088] The difference from Example 1 is that the weight of zirconium oxide was adjusted to 25 g and the weight of magnesium oxide was adjusted to 15 g.

[0089] Comparative Example 1

[0090] Titanium alloy TC4 was used to machine an implant having the same size parameters as those in Example 1, and the surface was sandblasted to form a titanium alloy TC4 implant with a rough surface.

[0091] After performance testing, the results shown in Table 1 were obtained.

[0092] Table 1 Performance test table category <![CDATA[Density g / cm 3 > Hardness HV Compressive strength MPa <![CDATA[Fracture toughness MPa·m 1 / 2 > Antibacterial rate Osseointegration Comparative Example 1 4.4 340 886 55 6% A small amount of proliferating fibroblasts can be seen around the implant, which undergo fibrosis and form fibrous callus. Example 1 1.62 1451 2630 8.3 92% There was no abnormal reaction of the tissue around the implantation site. The implant was tightly integrated with the bone tissue. Bone cells began to proliferate, trabeculae were visible, and the new bone developed well. Example 2 1.52 1449 2650 6.1 89% There was no abnormal reaction of the tissue around the implantation site. The implant was tightly integrated with the bone tissue. Bone cells began to proliferate, trabeculae were visible, and the new bone developed well. Example 3 1.72 1426 2580 7 93% There was no abnormal reaction of the tissue around the implantation site. The implant was tightly integrated with the bone tissue. Bone cells began to proliferate, trabeculae were visible, and the new bone developed well. Example 4 1.66 1460 2720 8.3 91% There was no abnormal reaction of the tissue around the implantation site. The implant was tightly integrated with the bone tissue. Bone cells began to proliferate, trabeculae were visible, and the new bone developed well.

[0093] According to the above table, the dental implant prepared in the embodiment of the present invention not only retains the good antibacterial property of silicon nitride and promotes bone integration, but also gives full play to the high hardness and high compressive resistance mechanical properties of silicon nitride, and also has the basic fracture toughness required for oral implants.

[0094] It should be emphasized that the above are only preferred embodiments of the present invention and do not limit the present invention in any form. Any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A one-piece silicon nitride implant, characterized in that: It includes the abutment, neck and root which are integrally molded by injection technology; The implant is provided with a first thread, a second thread and a third thread in sequence from the root to the neck, the first thread and the second thread are arranged at the root, and the third thread is arranged at the neck; The first threaded area is provided with a cutting groove.

2. The one-piece silicon nitride implant according to claim 1, characterized in that: The first thread is a conical external thread, and the second thread and the third thread are cylindrical external threads.

3. The one-piece silicon nitride implant according to claim 1, characterized in that: The root is provided with a porous layer on the surface, and the porosity of the porous layer ranges from 35% to 75%.

4. The one-piece silicon nitride implant according to claim 2, characterized in that: The cone angle of the conical external thread area is 10° to 15°.

5. The one-piece silicon nitride implant according to claim 4, characterized in that: The number of the grooves is 2 to 4, the angle between the grooves and the axis of the implant is half the angle of the cone, and the groove width is 1 to 2 mm.

6. The one-piece silicon nitride implant according to claim 1, characterized in that: The thread profile of the first thread is a sawtooth thread, the top arc radius is 0.1-0.2mm, the bottom transition arc radius is 0.4-0.5mm, the pitch is 0.6-1.0mm, the thread depth is 0.6-1.0mm, the thread length is 0.35L-0.4L, and L is the total length of the root and the neck.

7. The one-piece silicon nitride implant according to claim 1, characterized in that: The thread profile of the second thread is a trapezoidal thread, with a crest width of 0.2-0.4mm, a bottom transition arc radius of 0.4-0.5mm, a pitch of 0.6-1.0mm, a thread depth of 0.2-1.0mm, and a thread length of 0.4L-0.45L, where L is the total length of the root and the neck.

8. The one-piece silicon nitride implant according to claim 1, characterized in that: The thread profile of the third thread is a triangular thread, the top arc radius is 0.1-0.2mm, the bottom transition arc radius is 0.4-0.5mm, the pitch is 0.2-0.4mm, the thread depth is 0.02-0.5mm, the thread length is 0.15L-0.25L, and L is the total length of the root and the neck.

9. The one-piece silicon nitride implant according to claim 1, characterized in that: The axial length of the base is 3 to 6 mm.

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