A two-stage high-strength implant and a manufacturing method

Abstract

The present application belongs to the field of dental implant, and particularly relates to a two-segment high-strength implant and a manufacturing method. The two-segment high-strength implant comprises an implant and an abutment, the abutment is detachably connected with the implant, and the surface of the implant is provided with uniform primary and secondary holes, the diameter of the primary hole is 20-100 um, and the diameter of the secondary hole is 1-10 um. The implant has excellent mechanical properties and biocompatibility.

Description

Technical Field

[0001] This invention belongs to the field of dental implantology, and particularly relates to a two-stage high-strength implant and its manufacturing method. Background Technology

[0002] Dental implants are artificial teeth used to replace natural teeth for chewing, speech, and aesthetic functions after tooth loss or damage. Common materials are pure titanium or titanium alloys, which have good osseointegration properties. However, metallic materials have drawbacks such as ion leaching, allergies, gray lines at the cervical margin, bluish discoloration, and easy bacterial adhesion, making the development of alternative materials imperative.

[0003] Due to their excellent biocompatibility and aesthetics, ceramic materials have gradually become the next generation of materials for dental implants. Over the past decade, ceramic implants have been used clinically. However, during use, ceramic implants have also experienced issues such as fracture, infection, and insufficient osseointegration.

[0004] The main reasons for the above phenomenon include the following three aspects: 1) The design of the ceramic implant's shape and structure is defective, resulting in stress concentration in a small area. This area is subjected to excessive stress for a long time, which leads to breakage; 2) Defects in the manufacturing process of ceramic implants (including molding, sintering, machining, etc.) make it difficult for the ceramic implant to meet the requirements for densification and strength; 3) The surface treatment of ceramic implants is difficult. Because ceramic materials are usually hard, surface treatment is difficult. The surface structure, morphology and roughness formed by the surface treatment process are not ideal, and there are fewer bone integration sites, resulting in insufficient bone integration. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a two-stage high-strength implant and its manufacturing method. The implant obtained by this method has excellent mechanical properties and biocompatibility.

[0006] In a first aspect, the present invention provides a two-section high-strength implant, including an implant and an abutment, wherein the abutment and the implant are detachably connected, and the surface of the implant has uniform primary and secondary pores, wherein the diameter of the primary pores is 20-100 μm and the diameter of the secondary pores is 1-10 μm.

[0007] According to an embodiment of the present invention, the abutment extends to the outside of the gingiva, forming a portion that penetrates the gingiva and is inside the oral cavity, and is connected to the prosthesis. The implant and the abutment are manufactured using a two-stage molding technique, which has the advantages of good biocompatibility, good aesthetics, and more flexible surgical operation.

[0008] According to an embodiment of the present invention, the implant and the abutment are connected by screws.

[0009] According to an embodiment of the present invention, the abutment has a hollow internal structure, and screws are used to connect the implant to the abutment through screw holes inside the abutment and the implant. An anti-rotation groove is provided inside the abutment, which is used to connect the crown. The anti-rotation groove makes the crown more resistant to rotation, thereby improving the accuracy and convenience of wearing the tooth.

[0010] According to an embodiment of the present invention, a blind hole is provided at the top of the implant. The blind hole has a conical structure. The conical structure is used to seal the blind hole of the implant after being used with the abutment, so as to prevent bacteria from entering the blind hole and causing surgical failure.

[0011] According to an embodiment of the present invention, the blind hole is provided with an internal thread for connecting the implant and the abutment with screws. The internal thread has a smooth structure to prevent stress concentration when the screws connect the implant and the abutment, which could lead to implant failure.

[0012] According to an embodiment of the present invention, a cutting edge is provided at the lower part of the threaded area, and the cutting edge is eccentric by 0.1-0.5 mm, preferably 0.1-0.3 mm.

[0013] According to an embodiment of the present invention, the threaded region includes a base, the thread protrudes radially outward from the surface of the base, the diameter of the threaded region gradually decreases from top to bottom, and the bottom diameter of the threaded region is 0.1-0.5 mm smaller than the top diameter.

[0014] According to an embodiment of the present invention, the thread in the threaded area is a multi-start thread, such as a double-start or triple-start thread. The lead of the multi-start thread (i.e., the distance the thread travels axially per revolution) is a multiple of that of a single-start thread with the same pitch. This greatly reduces the implantation time. For example, the lead of a triple-start thread is three times the pitch of a single-start thread, thereby speeding up the implantation process.

[0015] According to an embodiment of the present invention, the threaded surface has a smooth structure.

[0016] Secondly, the present invention provides a method for forming the above-mentioned two-segment high-strength implant, comprising the following steps:

[0017] S1. The ceramic powder is loaded into the mold, sealed, and then cold isostatically pressed to obtain the green body;

[0018] S2. The green body is degreased and then sintered to obtain the green body;

[0019] S3. Machining the blank to obtain the implant semi-finished product;

[0020] S4. Sandblast and acid etch the semi-finished implant to obtain the implant.

[0021] According to an embodiment of the present invention, the ceramic powder is selected from at least one of alumina powder, zirconium oxide powder, alumina-toughened zirconium oxide powder, or zirconium oxide-toughened alumina powder, for example, zirconium oxide powder.

[0022] According to an embodiment of the present invention, the particle size of the zirconium oxide powder is 1-100 nm, preferably 5-50 nm, and more preferably 10-30 nm.

[0023] According to an embodiment of the present invention, the mold is made of an elastic material, such as rubber or plastic.

[0024] According to an embodiment of the present invention, the cold isostatic pressing includes the following steps: placing a mold containing ceramic powder into the high-pressure chamber of a cold isostatic press, starting the machine, gradually applying pressure to 250±50MPa, maintaining the pressure for 5-10 minutes, so that the powder is compacted under uniform pressure.

[0025] According to an embodiment of the present invention, the step between S1 and S2 includes the following steps: depressurizing the high-pressure cavity at a rate of 15±5MPa / min, demolding, and obtaining a green blank.

[0026] According to an embodiment of the present invention, the degreasing includes the following steps: keeping the green blank at a temperature of 400℃-700℃ for 2-4 hours.

[0027] According to an embodiment of the present invention, the sintering includes the following steps: first, degreasing the green body, and then holding it at 1200℃-1650℃ for 2-6 hours.

[0028] According to an embodiment of the present invention, the degreasing includes the following steps: heating the green blank to 700℃-1200℃ at a rate of 50-100℃ / h, holding it at that temperature for 1-2 hours, and then heating it to the sintering temperature at a rate of 100-200℃ / h.

[0029] According to an embodiment of the present invention, after sintering in step S2, the following steps are further included: cooling the sintered green blank to below 450℃±100℃ at a rate of 100℃±20℃ / h, and then naturally cooling it to room temperature to obtain the green body.

[0030] According to an embodiment of the present invention, the machining includes roughing and finishing, wherein roughing is performed using a common carbide end mill with a cutter diameter of 5-10mm, and finishing is performed using a special carbide end mill with a diameter of 1-10mm.

[0031] According to an embodiment of the present invention, the semi-finished implant after machining is first subjected to sandblasting treatment.

[0032] According to an embodiment of the present invention, the sandblasting process includes atomizing sand balls onto the surface of the implant semi-finished product. Preferably, the sand balls are selected from boron carbide, zirconium oxide, or alumina, preferably zirconium oxide, and more preferably alumina. Preferably, the diameter of the sand balls is 50-500 μm, more preferably 80-400 μm, and more preferably 100-200 μm. Further, the sandblasting pressure is 1-10 bar, for example 2-5 bar; the sandblasting working distance is 10-50 mm, for example 15 mm, preferably 8-10 mm; and the sandblasting moving speed is 1-20 mm / s, for example 5 mm / s.

[0033] According to an embodiment of the present invention, the etching process includes: etching the surface of the sandblasted implant semi-finished product with an etching solution.

[0034] According to an embodiment of the present invention, the etching solution comprises a first acid and hydrofluoric acid. Preferably, the first acid may be selected from at least one, two, or more of hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, etc. Further, the hydrofluoric acid is selected from 30-50 vol% hydrofluoric acid; the first acid is selected from 50-80 vol% nitric acid or 30-50 vol% sulfuric acid and 40-60 vol% phosphoric acid. More preferably, the etching solution is obtained by mixing 30-50 vol% hydrofluoric acid and 50-80 vol% nitric acid, preferably a mixture of 35-45 vol% hydrofluoric acid and 60-70 vol% nitric acid. Exemplarily, the etching solution comprises hydrofluoric acid (40 vol%) and nitric acid (50 vol%) in a volume ratio of 4:6.

[0035] According to an embodiment of the present invention, in the etching solution, the volume ratio of hydrofluoric acid to the first acid is (2-8):(8-2), preferably (4-6):(6-4), and more preferably 4:6.

[0036] According to an embodiment of the present invention, the etching time is 1 min to 120 min, preferably 20 to 40 min, and more preferably 30 min.

[0037] According to an embodiment of the present invention, the etching temperature is 30-100°C, for example, 70°C or 80°C.

[0038] Beneficial effects

[0039] 1) The two-section high-strength implant of this invention has a blind hole at the top of the implant. The blind hole has a conical structure and an internal thread. The conical structure is used to seal the blind hole after it is used with the abutment, preventing bacteria from entering the blind hole and causing surgical failure. The internal thread is a threaded structure, which can prevent stress concentration when the screw connects the implant and the abutment, which can lead to implant failure. The split implant consists of the implant body and the abutment separately. During the operation, the doctor can flexibly select different sizes and designs of implant bodies for implantation according to the specific conditions of the patient's alveolar bone, such as bone volume, bone density, alveolar bone height and width. After the implant body is implanted, the split implant undergoes a period of healing and stable osseointegration before the abutment is installed, reducing the risk of the implant affecting osseointegration due to external force interference during the healing process.

[0040] 2) The two-section high-strength implant of the present invention has a threaded area at the lower part of the implant. The diameter of the threaded area gradually decreases from top to bottom, and the thread in the threaded area is a multi-threaded thread. The multi-threaded thread not only has a larger lead but also a larger surface area, which can speed up the implantation speed, provide more attachment sites, and improve the stability of the implant.

[0041] 3) The two-section high-strength implant in this invention has a smooth thread in the threaded area, which can avoid stress concentration, achieve the effect of dispersing force, reduce the occurrence of mechanical complications of the implant, and improve the success rate of surgery.

[0042] 4) The material used in this invention is zirconia ceramic material. Zirconia powder with a particle size of 5-50 nanometers is selected and formed under specific temperature and pressure conditions. The resulting zirconia implant embryo has a monoclinic phase content of less than 2% before aging and a pre-monoclinic phase content of less than 3% after aging; the four-point bending strength is greater than 2000 MPa before aging and greater than 1800 MPa after aging; and the fracture toughness is greater than 10 MPa·m. 1 / 2 With a Young's modulus greater than 210 GPa and a hardness greater than 12 GPa, the implant has high strength and a long service life; moreover, zirconia ceramics have good light transmittance and color stability, which can meet patients' aesthetic needs.

[0043] 6) The inventors unexpectedly discovered that, under specific conditions, sandblasting followed by acid etching creates uniform primary and secondary pores on the implant surface. The primary pores have a diameter of 20-100 μm, and the secondary pores have a diameter of 1-10 μm. These primary and secondary pores allow osteoblasts to grow within the pores, greatly improving the stability of the product. Attached Figure Description

[0044] Figure 1 This is a schematic diagram of the implant structure;

[0045] Figure 2A sectional view of the implant, abutment, and screws after assembly;

[0046] Figure 3 This is a schematic diagram showing the surface area measurement of the threaded portion of a single-thread product.

[0047] Figure 4 A schematic diagram showing the surface area measurement of the threaded portion of a double-threaded product.

[0048] Figure 5 This is a static compression diagram for products according to YY / T 0521-2018.

[0049] Figure 6 A schematic diagram of the finite element analysis results for the unsmoothed thread section;

[0050] Figure 7 A schematic diagram of the finite element analysis results for the smooth design of the threaded section;

[0051] Figure 8 Implant manufacturing process flow chart;

[0052] Figure 9 A 100× electron microscope view of a ceramic implant after sandblasting and acid etching.

[0053] Figure 10 A 500× electron microscope view of a ceramic implant after sandblasting and acid etching.

[0054] Figure 11 A 2000× electron microscope view of a ceramic implant after sandblasting and acid etching.

[0055] Figure 12 A 5000× electron microscope view of a ceramic implant after sandblasting and acid etching.

[0056] In the diagram, 1-implant, 2-blind hole, 3-cutting edge, 4-soft tissue connection area, 5-threaded area, 6-abutment, 7-screw. Detailed Implementation

[0057] The structure of the present invention will be further described in detail below with reference to specific embodiments. It should be understood that the following embodiments are merely illustrative and explanatory of the present invention and should not be construed as limiting the scope of protection of the present invention. All technologies implemented based on the above content of the present invention are covered within the scope of protection intended by the present invention.

[0058] In the description of this invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0059] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0060] Example 1: Structure of a two-section high-strength implant

[0061] See Figure 1 , Figure 2 As shown, the two-section high-strength implant includes an implant 1 and an abutment 6. The abutment 6 is detachably connected to the end of the implant 1. In this embodiment, the implant 1 and the abutment 6 are connected by screws 7. The abutment 6 is used to extend to the outside of the gingiva to form a transgingival portion and connect with the prosthesis.

[0062] The upper part of implant 1 is provided with a blind hole, which has a conical structure. The conical structure is used to seal the blind hole of implant 1 after being used with the cover screw or abutment to prevent bacteria from entering the blind hole and causing surgical failure.

[0063] The blind hole is provided with an internal thread for connecting the implant 1 and the abutment 6 with screw 7. The internal thread has a smooth structure to prevent stress concentration when the screw connects the implant and the abutment, which could lead to implant failure.

[0064] The abutment 6 has a soft tissue connection area 4, which is located at the lower part of the abutment 6. After the implant 1 is inserted into the abutment 6, the soft tissue connection area 4 corresponds to the soft tissue. The soft tissue connection area 4 has an arc-shaped structure with an arc radius of R1-R5. The soft tissue connection area 4 can provide an attachment platform for the soft tissue, and the arc-shaped structure can fit and cover the surface of the soft tissue to form a seamless structure, preventing bacteria from entering the alveolar bone from the gap between the soft tissue connection area 4 and the soft tissue, causing inflammation, and thus leading to implant failure.

[0065] The implant 1 has a threaded area 5, and a cutting edge 3 is provided at the lower part of the threaded area 5. The height of the cutting edge 3 is 5-10mm, and the cutting edge 3 is eccentric by 0.1-0.5mm. The purpose of setting the cutting edge 3 is to make it easier for the operator to insert the product. As we all know, M=F×L. When the torque M is constant, the smaller L is and the larger F is, the greater the cutting force generated, and therefore the less effort is required. The bottom of the implant 1 is round, which can prevent maxillary sinus perforation and make the product safer.

[0066] The threaded area 5 includes the base body, and the thread protrudes radially outward from the surface of the base body. The diameter of the threaded area 5 gradually decreases from top to bottom. The bottom diameter of the threaded area 5 is 0.1-0.5 mm smaller than the top diameter. The larger the diameter of the threaded area 5, the greater the shear force that the implant 1 can withstand, and the larger the contact area with the alveolar bone, resulting in better product stability. This design increases the mechanical stability of the product.

[0067] The diameter of thread section 5 gradually decreases from top to bottom (hereinafter referred to as a gradually decreasing thread), which has the following advantages:

[0068] I. Initial stability

[0069] 1. In dental implants with tapered threads, the thread diameter gradually decreases from top to bottom during implantation. This structure allows for closer contact between the implant and the surrounding bone tissue. For example, in the initial stages of implantation, the coarser threads initially contact the cortical bone, and as the implantation depth increases, the threads gradually become thinner, allowing for better conformation to the cancellous bone. This close fit is like a specially designed key inserted into a corresponding lock, increasing the friction between the implant and the bone tissue, thereby effectively improving the initial stability of the implant.

[0070] 2. Compared with traditional equal-distance and equal-coarse threads, the gradient thread can adapt to different bone conditions (such as areas with different bone density), and can better grasp bone tissue in areas with low bone density, reducing micromovement of the implant after implantation and creating good conditions for subsequent osseointegration.

[0071] 3. Gradient threads can better distribute the stress on the implant under functional load to the surrounding bone tissue. When the patient chews food and generates biting force, the implant is subjected to axial and lateral forces. The gradient thread structure can make the stress more evenly distributed to the bone tissue along the gradient direction of the thread.

[0072] II. Osteointegration

[0073] 1. The gradient thread structure is similar to building a "growth track" for bone cells, which is conducive to the deposition and growth of new bone on the implant surface. Compared with traditional threads, the gradient thread can promote the contact and integration of bone tissue with the implant in the early stage after implantation, shortening the time of bone integration.

[0074] 2. Increased osseointegration area: Due to the shape characteristics of the tapered thread, it can provide a larger osseointegration area for the same implant size. As the thread gradually changes, the contact area between the implant surface and the bone tissue is increased in three-dimensional space. For example, as the thread changes from coarse to fine, the contact mode between each thread and the bone tissue is different. Overall, more bone tissue can interact with the implant surface. This is like establishing a wider "connection bridge" between the implant and the bone tissue, thereby improving the quality and strength of osseointegration and facilitating the long-term stable existence of the implant in the jawbone.

[0075] III. Aesthetic Effects

[0076] 1. Gingival Morphology Maintenance: Gradient thread implants provide good support for gingival tissue. After implant restoration, a suitable implant structure helps maintain the natural gingival morphology. Due to its good initial stability and osseointegration performance, the bone tissue around the implant can remain stable, thus providing stable support for the gingiva. For example, in single-tooth implant restoration, gradient thread implants can avoid gingival recession caused by implant loosening or bone resorption, making the gingival margin contour more natural and beautiful, meeting the requirements of aesthetic restoration.

[0077] 2. Reduce soft tissue complications: Gradient thread implants are beneficial to the health of the soft tissues around the implant. The gradient thread allows the implant to better adapt to the physiological environment in the oral cavity and reduce stimulation to the surrounding soft tissues. This is because it can maintain a stable position during implantation and functional loading and will not cause damage to the soft tissues such as the gums due to micromovement.

[0078] 3. Compared with non-gradient threaded implants, gradient threaded implants can reduce the incidence of soft tissue complications such as peri-implantitis, which is beneficial to maintaining the aesthetics and health of oral soft tissues after implant restoration.

[0079] The thread in threaded area 5 is a multi-start thread, such as a double-start or triple-start thread. The lead of a multi-start thread (i.e., the distance the thread travels axially per revolution) is a multiple of that of a single-start thread with the same pitch. This greatly reduces the time required for implantation surgery. For example, the lead of a triple-start thread is three times the pitch of a single-start thread, thus speeding up the implantation process.

[0080] Multi-start thread design maintains a fast insertion speed while increasing thread density and surface area. See [link / reference] Figure 3 and Figure 4 As shown, The surface area of ​​the threaded portion of a single-threaded wire and The diagram shows the surface area measurement of the threaded portion of the double-threaded structure. The surface area of ​​the threaded portion of the single-threaded structure is 191.73 square millimeters, and the surface area of ​​the threaded portion of the double-threaded structure is 193.7 square millimeters. It can be seen that the multi-threaded structure has a larger surface area and can provide more attachment sites. This allows implant 1 to achieve better stability in the early stage. This design helps to reduce vibration and displacement of implant 1 after implantation, thereby improving the long-term success rate of implant 1.

[0081] Furthermore, the threaded structure is an important structure for maintaining the bone volume in the neck. When the implant 1 is functioning, the force transmitted to the bone-implant interface by the implant 1 with a smooth neck design is mainly shear force. Shear force is the force that causes the most damage to bone tissue. Compared with shear force, bone tissue has a higher tolerance to pressure and tension. The multi-threaded design in this invention changes the type of force at the bone-implant interface, increases the tolerance of the bone tissue around the implant, and thus effectively reduces bone resorption in the implant neck.

[0082] The threaded structure in the neck allows the implant to better adapt to the physiological function of the surrounding bone and preserve the surrounding bone. The large threads at the bottom of the implant mainly increase mechanical stability in the early stage and increase osseointegration stability in the later stage. The threads in the neck do not play a role in increasing initial stability in the early stage of implantation, but reduce stress concentration in the neck. In the later stage, they reduce stress concentration during occlusion, converting shear force into tensile or compressive stress, reducing bone resorption, and promoting osseointegration.

[0083] When the implant material is zirconia, the failure of the zirconia implant 1 is usually due to stress concentration, which leads to point breakage and then extends to the line, causing the entire implant 1 to break. To solve this problem, the present invention uses a circular arc thread with a smooth R0.1-R0.5mm design to avoid stress concentration and achieve the effect of dispersing force, which greatly improves the success rate of surgery. The tooth angle of the circular arc thread is 50-70° and the thread height is 0.2-0.5mm.

[0084] According to the product embedding method and mechanical loading method in regulation YY / T 0521-2018, a static pressure of 200N was simultaneously applied to the smoothed and unsmoothed implants in this embodiment for analysis (other structures of the two types of implants are the same, and three sets of parallel tests were performed for each type of implant). See [link to relevant documentation]. Figure 5 The diagram shown is a schematic diagram of static compression of products according to regulation YY / T 0521-2018.

[0085] See Figure 6 and Figure 7As shown in Tables 1 and 2 (where the thread was calculated 3 times and the average value of the 3 calculations was taken), the implants corresponding to smooth and non-smooth threads were analyzed and statistically analyzed using the three-dimensional finite element method. The average maximum stress on the product with non-smooth thread design was 1043 MPa, while the average maximum stress on the product with smooth thread design was 561.7 MPa. It can be seen that the stress on the local area of ​​the smooth thread design of implant 1 is less than that on the non-smooth thread design of the product. That is, the smooth thread design of the product can effectively disperse stress and avoid stress concentration.

[0086] Table 1. Finite element analysis results of implants with unsmoothed threads.

[0087]

[0088] Table 2. Finite element analysis results of implants with smooth threads.

[0089] Group Maximum stress 1 561.8 MPa 2 561.2 MPa 3 562.1 MPa average value 561.7 MPa

[0090] Example 2: Method for forming a two-stage high-strength implant

[0091] In this embodiment, the raw material is zirconium oxide powder. The choice of zirconium oxide powder directly affects the mechanical properties of the implant. The inventors unexpectedly discovered that when the particle size of the zirconium oxide powder is 5-50 nanometers, the mechanical properties of the implant are the best.

[0092] See Figure 8 As shown, the method for forming zirconium oxide powder includes the following steps:

[0093] 1. Loading powder and cold isostatic pressing:

[0094] Zirconia powder is placed in an elastic mold, sealed, and then placed in a high-pressure container. A high-pressure pump is used to generate uniform static pressure on the mold through a liquid medium. The powder is compacted under isotropic pressure to form a blank with a certain density and strength.

[0095] 1) Mold preparation:

[0096] The flexible mold is designed and manufactured according to the shape and size of the implant, usually using materials such as rubber or plastic to ensure that the mold has good flexibility and sealing.

[0097] 2) Compaction:

[0098] Put an appropriate amount of zirconium oxide powder into the mold, place it into the high-pressure chamber of the cold isostatic press, start the machine, gradually apply pressure to about 250±50MPa, maintain the pressure for 5-10 minutes, and compact the powder under uniform pressure.

[0099] 3) Demolding process:

[0100] After pressing, the pressure is slowly released until it reaches 0 MPa before the mold can be removed. The depressurization rate is 15±5 MPa / min. The mold is then removed and demolded to obtain a zirconia green blank.

[0101] II. Sintering:

[0102] 1) Degreasing treatment:

[0103] Before sintering, the zirconia green body needs to be degreased to remove organic matter and impurities such as binders. The degreasing process usually involves holding the green body at a temperature of 400℃-700℃ for a period of time, depending on the size and shape of the green body, and is generally 2-4 hours.

[0104] 2) Heating phase:

[0105] After degreasing, the degreased green body is heated. The heating rate should not be too fast to avoid cracks or deformation of the green body due to thermal stress. Generally, multi-stage heating is adopted. For example, the temperature is first raised to 700℃-1200℃ at a rate of 50-100℃ / h and held for 1-2 hours. Then, the temperature is raised to the sintering temperature at a rate of 100-200℃ / h.

[0106] 3) Sintering stage:

[0107] The sintering temperature is usually between 1200℃ and 1650℃, and the holding time is 2-6 hours. During this stage, the particles in the green body undergo material migration, the pores are eliminated, and the green body gradually becomes denser.

[0108] 4) Cooling phase:

[0109] After sintering, the temperature is lowered to a cooling stage at a rate of 100℃±20℃ / h until it reaches below 450℃±100℃. Then it is allowed to cool naturally to room temperature to obtain the implant blank.

[0110] The mechanical properties and various indicators of the implant embryos manufactured using the molding process of this invention are tested, and the results are shown in the table below. The data shows that the implant embryos manufactured using the molding process of this invention exhibit significant improvements in all indicators.

[0111] Referring to Table 3, static pressing and sintering are performed according to the above steps to obtain the implant blank.

[0112] Table 3 Molding conditions of zirconia powder in different embodiments

[0113]

[0114] Table 4. Indicators of implant embryos prepared in Example 4

[0115]

[0116] Example 7 Machining and Surface Treatment

[0117] The implant blanks obtained in Examples 3-6 are machined to obtain the structure in Example 1. The machining is carried out by machining with tools in separate steps. Roughing is done with ordinary alloy end mills with a diameter of 5-10mm, and finishing is done with special alloy end mills with a diameter of 1-10mm.

[0118] Surface treatment process

[0119] Ceramic implant sandblasting and acid etching is a surface treatment technique used to improve the integration of the implant with the surrounding bone.

[0120] Sandblasting involves impacting the implant surface with particles of a specific diameter at high speed, creating a rough surface. This roughness increases the implant's surface area, providing more space for new bone formation and promoting osseointegration. Simultaneously, appropriate roughness facilitates osteoblast adhesion, proliferation, division, differentiation, extracellular matrix secretion, and osteogenic processes.

[0121] Acid etching involves exposing the implant to a certain concentration of acid for a chemical reaction. This creates tiny pores on the surface of the implant, which can promote the attachment of pseudopodia of osteoblasts, thus facilitating the attachment and growth of osteoblasts.

[0122] This invention involves sandblasting followed by acid etching on the machined implant semi-finished product. After sandblasting and acid etching, uniform primary and secondary pores can be formed on the product surface. The primary pores are 20-100um and the secondary pores are 1-10um. The formation of primary and secondary pores allows osteoblasts to grow in the pores, greatly improving the stability of the product.

[0123] Specifically, the machined implant semi-finished product is first subjected to sandblasting. Sandblasting involves spraying sand balls onto the surface of the implant semi-finished product. The sand balls are selected from boron carbide, zirconium oxide, or alumina, preferably zirconium oxide, and more preferably alumina. Preferably, the diameter of the sand balls is 50-500 μm, more preferably 80-400 μm, and more preferably 100-200 μm. Further, the sandblasting pressure is 1-10 bar, for example, 2-5 bar; the sandblasting working distance is 10-50 mm, for example, 15 mm, preferably 8-10 mm; and the sandblasting moving speed is 1-20 mm / s, for example, 5 mm / s.

[0124] The etching process includes treating the surface of the semi-finished implant after sandblasting with an etching solution.

[0125] The etching solution comprises a first acid and hydrofluoric acid. The first acid can be selected from at least one, two, or more of hydrochloric acid, sulfuric acid, nitric acid, and phosphoric acid. Further, the hydrofluoric acid is selected from 30-50 vol% hydrofluoric acid; the first acid is selected from 50-80 vol% nitric acid, or 30-50 vol% sulfuric acid, or 40-60 vol% phosphoric acid. More preferably, the etching solution is obtained by mixing 30-50 vol% hydrofluoric acid and 50-80 vol% nitric acid, more preferably by mixing 35-45 vol% hydrofluoric acid and 60-70 vol% nitric acid. Exemplarily, the etching solution comprises hydrofluoric acid (40 vol%) and nitric acid (50 vol%) in a volume ratio of 4:6.

[0126] In the etching solution, the volume ratio of hydrofluoric acid to the first acid is (2-8):(8-2), preferably (4-6):(6-4), and more preferably 4:6.

[0127] The etching time is 1 min to 120 min, preferably 20 to 40 min, and more preferably 30 min.

[0128] The etching temperature is 30-100℃, for example, 70℃ or 80℃.

[0129] Table 5 Sandblasting and acid etching conditions for different green bodies

[0130]

[0131] Because the implant products prepared by this invention are Class III medical device implants, there are strict requirements for the product's washing and packaging environment and the initial contamination of the product with bacteria and particles after washing and packaging. The product's washing and packaging environment should be no less than Class 100,000, and the product after washing and packaging should meet the requirement that the initial contamination bacteria should be ≤100 cfu / g. The washing parameters are a temperature of 40-80℃ and a washing time of 20-60 minutes.

[0132] There are three sterilization methods for medical devices: irradiation sterilization, ethylene oxide sterilization, and high-pressure steam sterilization. Irradiation sterilization causes color changes and a decrease in mechanical properties in ceramic materials, so it is not used. High-pressure steam sterilization is complex and affects the material's lifespan, so it is also not used. Ethylene oxide sterilization does not affect product performance and is more convenient for batch operations, therefore it is used. After sterilization, the product must undergo testing upon returning to the factory, including testing for sterility, bacterial endotoxin ≤0.25 EU / mL, and ethylene oxide residue ≤10 μg / g.

[0133] The specific embodiments of the present invention have been described above by way of example. However, the scope of protection of the present invention is not limited to the above exemplary embodiments. Any modifications, equivalent substitutions, improvements, etc., made by those skilled in the art within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A method of forming a two-stage high-strength implant, characterized by, The two-stage high-strength implant comprises an implant and an abutment, the abutment is arranged at the end of the implant, and the abutment is integrally formed with the implant, the surface of the implant is provided with uniform primary and secondary holes, the diameter of the primary hole is 20-100 um, and the diameter of the secondary hole is 1-10 um; The implant is provided with a threaded area, the lower part of the threaded area is provided with a cutting edge, and the cutting edge is eccentric by 0.1-0.5 mm; The threaded area comprises a base body, threads protrude radially and outwardly from the surface of the base body, the diameter of the threaded area gradually decreases from top to bottom, and the diameter of the bottom of the threaded area is smaller than the diameter of the top by 0.1-0.5 mm; the threads of the threaded area are multi-threaded threads, the surface of the threads is a smooth structure, the threads are circular-arc threads, the smooth R0.1 mm~R0.5 mm design is realized at the circular-arc threads, the thread angle of the circular-arc threads is 50~70°, and the thread height is 0.2~0.5 mm. The forming method comprises the following steps: S1. The ceramic powder is loaded into a mold, and after sealing, cold isostatic pressing is performed to obtain a green body; S2. After debinding, the green body is sintered to obtain a blank; S3. The blank is machined to obtain an implant semi-finished product; S4. The implant semi-finished product is sandblasted and acid-etched to obtain an implant; The ceramic powder is selected from zirconia powder; the particle size of the zirconia powder is 5~50 nm; The debinding comprises the following steps: the green body is kept at a temperature of 400℃-700℃ for 2-4 hours; After debinding, the debound green body is heated at a speed of 50-100℃ / h to 700℃-1200℃, kept for 1-2 hours, and then heated at a speed of 100-200℃ / h to the sintering temperature; The sintering comprises the following steps: keeping at 1200℃-1650℃ for 2-6 hours; The acid etching comprises: using an etching liquid to etch the surface of the sandblasted implant semi-finished product, removing easily removable substances in the blank, and forming a hole structure on the outer surface; The etching liquid is a mixture of 35-45vol% hydrofluoric acid and 60-70vol% nitric acid, and the volume ratio of the hydrofluoric acid and the nitric acid is 4~6:6~4; The etching time is 20min-40min, and the etching temperature is 70-80℃.

2. The method of claim 1, wherein the two-stage high-strength implant is formed by the steps of: The abutment is internally hollow, and an anti-rotation groove is arranged in the abutment, the anti-rotation groove is used for connecting a dental crown.

3. The method of claim 1, wherein the two-stage high-strength implant is formed by the steps of: The top end of the implant is provided with a blind hole, the blind hole is in a conical structure, and the conical structure is used in cooperation with a covering screw or an abutment to close the blind hole of the implant; An internal thread is arranged in the blind hole, which is used for connecting the implant and the abutment by using a screw, and the internal thread is a smooth structure.

4. The method of claim 1, wherein the two-stage high-strength implant is formed by the steps of: The cold isostatic pressing comprises the following steps: the mold loaded with the ceramic powder is placed in the high-pressure cavity of the cold isostatic pressing machine, the machine is started, the pressure is gradually applied to 250±50MPa, and the pressure is kept for 5-10 minutes to compact the powder under uniform pressure.

5. The method of claim 4, wherein the two-stage high-strength implant is formed by the steps of: Between steps S1 and S2, the following step is included: the high-pressure cavity is unloaded at a rate of 15±5MPa / min, demolded, and a green body is obtained.

6. The method of claim 1, wherein the two-stage high-strength implant is formed by the steps of: Step S4 comprises the step of blasting the machined implant semi-finished product.

7. The method of claim 6, wherein the two-stage high-strength implant is formed by the steps of: The blasting comprises blasting sand balls onto the surface of the implant semi-finished product, the sand balls being selected from boron carbide, zirconium oxide or aluminium oxide, the sand balls having a diameter of 50-500 μm.

8. The method of claim 6, wherein the two-stage high-strength implant is formed by the steps of: The blasting has a pressure of 1-10 bar, a working distance of 10-50 mm and a movement speed of 1-20 mm / s.

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