Surface treatment method for bioactivity and biocompatibility of false tooth and implant

Abstract

The invention relates to the technical field of biomedical materials, and discloses a surface treatment method for biological activity and biocompatibility of a false tooth and an implant, which comprises the following steps: a) carrying out surface pretreatment on a matrix of the false tooth or the implant; b) applying a layer of composite coating containing hydroxyapatite particles and a biocompatible resin adhesive on the surface of the pretreated matrix; c) performing low-temperature thermocuring on the composite coating to form a composite coating; and d) precisely polishing the surface of the cured composite coating to selectively remove part of the resin adhesive on the surface. The composite coating which is firmly combined with the substrate and has stable chemical properties is obtained through mechanical locking on the surface of the substrate and chemical combination of the internal interface of the coating; meanwhile, through low-temperature curing and surface activation treatment, the hydroxyapatite is exposed on the surface of the coating on the premise of retaining the biological activity of the hydroxyapatite, so that the coating is endowed with an effective biological function.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of biomedical materials, in particular to a biological activity and biocompatibility surface treatment method of denture and implant. BACKGROUND

[0002] In the field of medical implants, titanium and its alloys are widely used due to their mechanical properties and biological inertness. However, the biological inert surface of titanium and its alloys cannot form a direct biological bond with bone tissue, which may lead to instability of the interface between the implant and the surrounding bone. To solve this problem, the prior art usually applies a layer of biologically active coating to the surface of titanium alloy, in which hydroxyapatite is one of the most widely used coating materials due to its similar chemical composition to the inorganic components of human bone.

[0003] Currently, the technology for preparing hydroxyapatite coating mainly includes high-temperature and low-temperature methods. High-temperature technology is represented by plasma spraying, which melts hydroxyapatite powder by instantaneous high temperature and sprays it onto the surface of the substrate. However, the high-temperature environment of the plasma will cause thermal decomposition of hydroxyapatite, generating other phases of calcium phosphate or amorphous phases, thereby changing its original chemical structure and reducing or losing its biological activity of inducing bone formation. In addition, the large difference in thermal expansion coefficient between the ceramic coating and the metal substrate will generate a large amount of residual stress during the cooling process, which will easily cause the coating to crack or peel off, affecting the long-term bonding stability of the coating.

[0004] To avoid the damage of high temperature to the activity of hydroxyapatite, low-temperature preparation technology has been developed, one of the typical methods of which is to disperse hydroxyapatite particles as fillers in a polymer binder to form a composite coating, which is then coated on the surface of the substrate and solidified at low temperature. However, this technology also has inherent technical problems. First, the titanium alloy surface usually has a dense oxide film, which is chemically inert, resulting in limited physical adhesion between the polymer coating and the substrate. Second, the physical and chemical properties of hydroxyapatite, as an inorganic ceramic material, and the polymer binder are greatly different, and the interfacial compatibility between them is poor, which easily leads to agglomeration of hydroxyapatite particles in the resin and weakens the interfacial bonding between the filler and the binder, affecting the cohesive strength of the coating itself. The most critical technical obstacle is that after the composite coating is solidified into a film, the polymer binder will inevitably completely cover the hydroxyapatite particles, forming a continuous, non-biologically active polymer film on the outermost layer of the coating, which hinders the direct contact of hydroxyapatite with the external physiological environment, and makes its biological activity ineffective. SUMMARY

[0005] In view of the deficiencies of the prior art, the application provides a biological activity and biocompatibility surface treatment method for dentures and implants, which solves the problems of insufficient coating and metal substrate bonding strength and loss of biological activity of the coating surface caused by complete coating of the active filler with the polymer adhesive during the low-temperature preparation of the hydroxyapatite composite coating.

[0006] To achieve the above object, the application is implemented by the following technical scheme: a biological activity and biocompatibility surface treatment method for dentures and implants, comprising the following steps:

[0007] a) performing surface pretreatment on the substrate of the denture or implant;

[0008] b) applying a composite coating containing hydroxyapatite particles and biocompatible resin adhesive on the pretreated substrate surface;

[0009] c) performing low-temperature thermal curing on the composite coating to form a composite coating;

[0010] d) performing precision polishing on the surface of the cured composite coating to selectively remove part of the resin adhesive on the surface, so that the hydroxyapatite particles coated inside are exposed to the outermost surface of the coating.

[0011] Preferably, the hydroxyapatite particles in the composite coating are hydroxyapatite surface-modified by a silane coupling agent, and the biocompatible resin adhesive is an organic silicon-modified epoxy resin.

[0012] Preferably, when the substrate is a titanium alloy implant, the surface pretreatment in step a) is anodic electrolysis of the substrate in an electrolyte to form a micro concave structure on the surface caused by intergranular corrosion.

[0013] Preferably, when the substrate is a zirconium dioxide denture, the surface pretreatment in step a) is to apply a layer of silane coupling agent on the surface of the substrate.

[0014] Preferably, the low-temperature thermal curing temperature in c) ranges from 100 to 150 DEG C.

[0015] Preferably, the precision polishing in d) adopts a magnetic fluid polishing process.

[0016] A biological activity denture or implant, comprising:

[0017] a substrate;

[0018] a composite coating arranged on the surface of the substrate;

[0019] wherein the composite coating is composed of the following components in mass percentage:

[0020] Hydroxyapatite microparticles: 70% to 80%;

[0021] Bio-compatible silicone-modified epoxy resin adhesive: 20% to 30%; and, the hydroxyapatite microparticles of the outermost surface of the composite coating are exposed.

[0022] Preferably, the substrate is a titanium alloy, and the surface of the substrate has a micro-concave structure between the substrate and the composite coating.

[0023] Preferably, the substrate is a zirconium dioxide, and a silane coupling agent layer is provided between the substrate and the composite coating.

[0024] Preferably, the hydroxyapatite microparticles are microparticles that are surface-modified with an organic functional group and have a particle size D50 of 5-15 microns.

[0025] The present application provides a method for processing the bioactivity and biocompatibility of a denture and implant.

[0026] The present application has the following advantages:

[0027] 1. The present application forms a micro-mechanical locking structure on the surface of the substrate by electrochemical treatment, which provides a physical anchoring basis for the subsequent coating. At the same time, the surface-modified hydroxyapatite in the composite coating forms an effective interfacial bond with the silicone-modified epoxy resin, which improves the cohesive strength of the coating itself. The synergistic effect of these two mechanisms makes the final coating have anti-peeling ability, ensuring its long-term adhesion on the substrate.

[0028] 2. The low-temperature curing step in the process of the present application completely preserves the chemical structure and functional properties of hydroxyapatite as a bioactive component. More importantly, the present application selectively removes the resin layer covering the surface of the hydroxyapatite microparticles by adding a surface activation treatment process after the coating is cured, so that the bioactive particles are exposed to the outermost layer of the coating, thereby constructing a functional interface that can directly interact with the external environment, solving the technical problem that the active filler is completely covered by the inert adhesive and cannot function.

[0029] 3. The bio-compatible adhesive used in the present application is a special silicone-modified epoxy resin. The polymer network formed after the resin is cured has high crosslinking density and hydrolysis resistance. This stable chemical structure can effectively fix all components in the coating, significantly reducing the possibility of organic matter leaching from the coating, thereby ensuring the overall biocompatibility of the coating. DETAILED DESCRIPTION

[0030] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of the present application.

[0031] The present application provides a kind of denture and implant bioactive and biocompatibility surface treatment method, comprising the following steps:

[0032] a) the substrate of denture or implant is pre-treated on surface;

[0033] b) a layer of composite coating containing hydroxyapatite microparticles and biocompatible resin adhesive is applied on the surface of the pre-treated substrate;

[0034] c) the composite coating is low-temperature heat cured to form a composite coating;

[0035] d) the surface of the cured composite coating is precisely polished to selectively remove part of the resin adhesive on the surface, so that the hydroxyapatite microparticles inside are exposed to the outermost surface of the coating.

[0036] The first step is the surface pretreatment of the substrate. This step is to establish a stable bonding interface between the substrate material and the subsequent composite coating. For substrates of different materials, corresponding pretreatment techniques are used. When the substrate is a titanium alloy material, anodic electrolysis treatment is used. The titanium alloy implant is placed in a specific electrolyte as the anode and a direct current is passed through. Due to the difference in anodic dissolution potential of the elements in the titanium alloy, some elements will preferentially dissolve during electrolysis, forming micron-sized irregular recess and pore structures on the surface of the substrate. These three-dimensional structures increase the surface area of the substrate and provide a large number of physical locking points for the coating material during subsequent coating curing, forming a mechanical embedded riveting and establishing the physical bonding force between the substrate and the coating. When the substrate is a zirconia ceramic material, silane coupling agent is used for treatment. This treatment applies silane coupling agent containing specific organic functional groups to the surface of zirconia. One end of the silane coupling agent molecule can chemically react with the inorganic zirconia surface to form a stable chemical bond, while the other end of the organic functional group can covalently bond with the resin adhesive in the subsequent coating during curing. Through this chemical connection, a molecular level connection is formed between the inorganic substrate and the organic coating.

[0037] The second step is the application of the composite coating. This step applies a composite coating with hydroxyapatite microparticles as bioactive fillers and silicone-modified epoxy resin as biocompatible binder to the surface of the pretreated substrate. The hydroxyapatite microparticles are pre-treated by surface modification. The modification uses silane coupling agents to graft organic functional groups onto the surface of the inorganic hydroxyapatite particles. This improves the interfacial compatibility of the inorganic filler and the organic resin binder, inhibits phase separation between the two during mixing and curing, and ensures that the hydroxyapatite microparticles are uniformly and stably dispersed throughout the resin matrix to form a homogeneous composite coating.

[0038] The third step is low-temperature thermal curing. This step involves heating the workpiece with the applied composite coating to a specific temperature range. The temperature is set high enough to initiate the cross-linking reaction of the silicone-modified epoxy resin, causing it to transition from a liquid slurry to a solid film with a certain mechanical strength, thereby firmly covering and fixing the hydroxyapatite microparticles on the substrate surface. At the same time, the curing temperature must be lower than the critical temperature at which the hydroxyapatite decomposes and loses its inherent bioactivity. Through this low-temperature curing, the physical structure of the coating is ensured to be complete and formed, while the chemical structure and functional integrity of the core bioactive components are maintained.

[0039] The fourth step is the surface activation treatment of the coating. This step is the key to achieving the final technical effect of the invention. After low-temperature curing, the outermost surface of the composite coating is a smooth layer of resin binder, and the internal hydroxyapatite microparticles are completely covered and cannot directly contact the external environment, so their bioactivity cannot be expressed. This step uses the magnetic fluid polishing process to treat the surface of the cured coating. The magnetic fluid polishing technology takes advantage of the significant difference in mechanical hardness and wear resistance between the organic resin binder and the inorganic hydroxyapatite microparticles. By precisely controlling the shear stress generated by the magnetic fluid under the action of the magnetic field, the resin binder, which is softer, can be removed more efficiently, while the wear of the harder hydroxyapatite microparticles is minimal. This differential material removal rate allows for a macroscopically uniform and smooth polishing process that microscopically selectively peels off the surface resin, ultimately exposing the top part of the originally covered hydroxyapatite microparticles to the outermost layer of the coating, thereby creating a functionalized surface with bioactivity that can directly contact human tissues.

[0040] Example 1

[0041] This example provides a specific preparation process for a bioactive and biocompatible surface treatment method.

[0042] First step: preparation of bioactive composite coating

[0043] 1.1 Hydroxyapatite powder preparation: Dicalcium phosphate dehydrate and deionized water were mixed in a mass-volume ratio of 1:2.4 and then placed in a reaction kettle. The temperature was raised to 200°C and the mixture was reacted for 3 hours. After the reaction, the product was washed with deionized water until the pH value was 6.5, and then dehydrated, dried. The dried material was placed in an alumina ball mill tank and ground for 5 hours to obtain a micro-powder with a D50 particle size of 10 μm. Finally, the micro-powder was surface treated with a silane coupling agent.

[0044] 1.2 Preparation of silicone-modified epoxy resin: Methyl triethoxysilane, deionized water, epoxy resin, and amino silane were placed in a reaction kettle and reacted at 50°C and 0.8 MPa for 5 hours to obtain a silicone-modified epoxy resin.

[0045] 1.3 Compound coating preparation: The hydroxyapatite micro-powder prepared in step 1.1 was mixed with the silicone-modified epoxy resin prepared in step 1.2 in a mass ratio of 75:25, anhydrous ethanol was added for dilution, and the mixture was stirred uniformly to form a slurry.

[0046] Second step: substrate surface pretreatment

[0047] The titanium alloy substrate was placed as an anode in an electrolyte and a direct current voltage of 5V was applied. The electrolysis was carried out at room temperature for 2 minutes.

[0048] Third step: application and curing of the composite coating

[0049] The slurry prepared in step 1.3 was applied to the pretreated substrate surface using a spraying process, and the excess slurry was removed by centrifugation. Subsequently, the workpiece was placed in an oven at 125°C for 5 hours, and then left to stand for more than 48 hours after removal.

[0050] Fourth step: surface activation treatment of the coating

[0051] The surface of the cured composite coating was treated using a magnetorheological polishing process to expose the hydroxyapatite particles to the outermost surface of the coating.

[0052] Example 2

[0053] This example provides a specific preparation process of a bioactive and biocompatible surface treatment method.

[0054] First step: preparation of bioactive composite coating

[0055] 1.1 Hydroxyapatite powder preparation: After mixing dicalcium phosphate dehydrate and deionized water, put them into a reactor, heat to 180℃ and react for 2 hours. After the reaction, wash the product with deionized water until the pH value is 6.0, then dehydrate and dry. Put the dried material into an alumina ball mill tank and grind for 4 hours to obtain a micro powder with a D50 particle size of 15 μm. Finally, use a silane coupling agent to treat the surface of the micro powder.

[0056] 1.2 Preparation of silicone-modified epoxy resin: Put methyl triethoxysilane, deionized water, epoxy resin and amino silane into a reactor and react at 40℃ and 0.5 MPa for 4 hours to obtain a silicone-modified epoxy resin.

[0057] 1.3 Compound coating preparation: Mix the hydroxyapatite micro powder prepared in step 1.1 with the silicone-modified epoxy resin prepared in step 1.2 at a mass ratio of 70:30, add anhydrous ethanol for dilution and stir uniformly to form a slurry.

[0058] Second step: Surface pretreatment of the substrate

[0059] Put the titanium alloy substrate as an anode into an electrolyte and apply a direct current voltage of 2V at room temperature for 1 minute.

[0060] Third step: Application and curing of the composite coating

[0061] Apply the slurry prepared in step 1.3 to the surface of the pretreated substrate by dip coating process and remove the excess slurry by centrifugation. Then, place the workpiece in an oven at 100℃ for 4 hours and let it stand for more than 48 hours after removal.

[0062] Fourth step: Surface activation treatment of the coating

[0063] Use magnetic fluid polishing process to treat the surface of the cured composite coating to expose the hydroxyapatite particles to the outermost surface of the coating.

[0064] Example 3

[0065] This example provides a specific preparation process of a bioactive and biocompatible surface treatment method.

[0066] First step: Preparation of bioactive composite coating

[0067] 1.1 Hydroxyapatite powder preparation: After mixing dicalcium phosphate dehydrate and deionized water, put them into a reactor, heat to 180℃ and react for 2 hours. After the reaction, wash the product with deionized water until the pH value is 6.0, then dehydrate and dry. Put the dried material into an alumina ball mill tank and grind for 4 hours to obtain a micro powder with a D50 particle size of 15 μm. Finally, use a silane coupling agent to treat the surface of the micro powder.

[0068] 1.2 Preparation of silicone-modified epoxy resin: Methyltriethoxysilane, deionized water, epoxy resin and aminosilane were placed in a reactor and reacted at 60°C and 1.0 MPa for 6 hours to obtain silicone-modified epoxy resin.

[0069] 1.3 Preparation of composite coating: Mix the hydroxyapatite powder prepared in step 1.1 and the organosilicon-modified epoxy resin prepared in step 1.2 in a mass ratio of 80:20, add anhydrous ethanol to dilute and stir evenly to form a slurry.

[0070] Step 2: Substrate surface pretreatment

[0071] The titanium alloy substrate was placed in the electrolyte as an anode, a DC voltage of 8 V was applied, and electrolysis was carried out at room temperature for 3 minutes.

[0072] Step 3: Application and curing of composite coating

[0073] Apply the slurry prepared in step 1.3 to the pretreated substrate surface using a brush coating process. Remove excess slurry by centrifugation. Next, heat the workpiece in an oven at 150°C for 6 hours and then allow it to rest for at least 48 hours.

[0074] Step 4: Surface activation treatment of coating

[0075] The surface of the solidified composite coating is treated by magnetorheological polishing process so that the hydroxyapatite particles are exposed on the outermost surface of the coating.

[0076] Comparative Example 1

[0077] Compared with Example 1, the difference is that in the preparation of the composite coating in step 1.3, the mass ratio of hydroxyapatite powder to silicone-modified epoxy resin is 50:50, and the rest are the same.

[0078] Comparative Example 2

[0079] Compared with Example 1, the difference is that in step 1.1, after the hydroxyapatite powder is obtained, the surface treatment is not performed using a silane coupling agent, and the rest are the same.

[0080] Comparative Example 3

[0081] Compared with Example 1, the difference is that the substrate surface pretreatment in step 2 is omitted, and the slurry prepared in step 1.3 is directly applied to the untreated titanium alloy substrate surface, and the rest are the same.

[0082] Comparative Example 4

[0083] The difference compared with Example 1 is that the coating surface activation treatment of Step 4 is omitted, and the composite coating after curing of Step 3 is the final product, and the rest are the same.

[0084] Comparative Example 5

[0085] The difference compared with Example 1 is that in the curing of the composite coating of Step 3, the workpiece is placed in an oven at 450°C for heat treatment, and the rest are the same.

[0086] Comparative Example 6

[0087] The difference compared with Example 1 is that in Step 1.2, methyl triethoxysilane is not used for modification, and an unmodified conventional epoxy resin is prepared and used as an adhesive, and the rest are the same.

[0088] Test Example 1: Coating and Substrate Bonding Strength Test

[0089] This test example aims to quantitatively evaluate the bonding strength of the coatings prepared in Example 1 and Comparative Examples 1, 2, 3. The test method uses the pull-out method, and the specific experimental steps are as follows:

[0090] Test sample preparation: take the samples coated and cured completed prepared in Example 1 and Comparative Examples 1-3.

[0091] Test pull head bonding: select a cylindrical steel pull head with a diameter of 14 mm. Use sandpaper to polish the bonding surface of the pull head, and then ultrasonically clean with acetone and dry. Take the two-component epoxy resin adhesive, evenly coat it on the end face of the pull head, and vertically bond the pull head to the surface of the coating to be tested. Apply constant pressure and keep at room temperature for 24 hours to allow the adhesive to fully cure.

[0092] Test area definition: use a special ring cutting tool, with the bonded pull head as the center, cut the coating along the edge of the pull head. The cutting depth needs to reach the surface of the titanium alloy substrate to ensure that only the circular area directly below the pull head is stressed during testing.

[0093] Tensile load application: fix the test sample with the pull head on the base of the portable pull-out tester. Connect the pull jaw of the tester to the pull head. Start the tester to apply a tensile load perpendicular to the surface of the coating to the pull head at a constant loading rate of 0.2 MPa / s.

[0094] Data recording and calculation: the instrument automatically records the maximum load value (N) when the coating separates and fails. Divide this load value by the cross-sectional area of the pull head (153.9 mm 2 ), and calculate the bonding strength of the coating and the substrate (MPa). Repeat the measurement 5 times for each group of samples and record all the data.

[0095] Table 1: Coating bond strength test data of different samples

[0096]

[0097]

[0098] The bond strength test data clearly shows the effect of substrate surface topography on the adhesion of the coating. By electrochemically treating the titanium alloy substrate surface to form micro concave structures, the subsequently coated composite material can form a physical mechanical lock with the substrate after curing. This mechanical anchoring structure can provide significantly higher tensile peel resistance compared to the coating applied directly on a smooth substrate surface, solving the technical problem of weak bonding between the coating and the substrate.

[0099] The cohesive strength of the coating itself is another key factor determining the overall bonding performance. By surface modification treatment of the hydroxyapatite filler, an effective chemical bond connection is established between the inorganic filler and the silicone-modified epoxy resin adhesive. This improves the interfacial compatibility of the filler and the resin matrix, allowing the stress to be effectively transmitted within the composite material rather than prematurely causing damage at the weak interface. This improves the overall cohesive strength of the coating material, ensuring the structural integrity of the coating.

[0100] The mass ratio of each component in the composite coating is also a decisive factor affecting the mechanical properties of the final coating. Experimental results show that in the material system used, there is a specific mass ratio of hydroxyapatite filler to resin adhesive, at which the composite coating formed by curing can withstand a higher damage load than other ratios. This confirms that by precisely controlling the composition ratio of each component, the macroscopic mechanical strength of the final coating can be effectively regulated.

[0101] Test Example 2: In vitro bioactivity test of coating

[0102] This test example aims to quantitatively evaluate the ability of the coating samples prepared in Example 1, Comparative Example 4, and Comparative Example 5 to induce apatite deposition by immersion in Simulated Body Fluid (SBF), which is used to characterize the in vitro bioactivity of the coating.

[0103] Experimental steps:

[0104] SBF solution preparation: according to the formula of adding 8.035 g NaCl, 0.355 g NaHCO3, 0.225 g KCl, 0.231 g K2HPO4·3H2O, 0.311 g MgCl2·6H2O, 0.292 g CaCl2, 0.072 g Na2SO4 per liter of deionized water, dissolve each reagent in a 37.0 °C water bath. Adjust the pH of SBF to 7.40 accurately using Tris and 1 M HCl solution.

[0105] Sample initial weighing: the coated sample with a size of 10 mm x 10 mm x 2 mm was ultrasonically cleaned in acetone for 5 minutes, rinsed with deionized water, and then placed in a 60 °C oven to dry to a constant weight. The initial mass (m0) of each sample was weighed using an analytical balance with a precision of 0.01 mg, and recorded.

[0106] Soaking experiment: each weighed sample was placed independently in a clean polyethylene sealed container. According to the ratio of sample coating surface area to SBF volume of 10 mm 2 : 1 mL, 24 mL of SBF solution was added to each container (the total surface area of the sample was 240 mm 2 ). All sealed containers were placed in a constant temperature shaker at 37.0 °C, and slowly shaken at a speed of 50 rpm for 14 days of soaking.

[0107] Sample secondary weighing: after the soaking period, the sample was removed from the SBF solution and the surface was gently rinsed with deionized water to remove residual salt. The rinsed sample was dried to a constant weight in a 60 °C oven. The final mass (m1) of each sample was weighed using the same analytical balance, and recorded.

[0108] Data calculation: the mass increase value per unit area (Am / A) of the sample was calculated by the following formula: Am / A = (m1-m0) / A, where A is the total surface area of the sample coating (2.4 cm 2 ). Each group of samples was tested 3 times, and all data were recorded.

[0109] Experimental data:

[0110] Table 2: Mass increase per unit area of different samples after 14 days of soaking in simulated body fluid

[0111]

[0112] By comparing the mass change of the samples before and after immersion in the simulated body fluid, it can be determined that the final coating surface treatment step is necessary to obtain bioactivity. The sample without surface activation treatment has no significant change in mass after immersion. The mechanism is that the cured silicone-modified epoxy resin forms a continuous physical barrier on the outermost layer of the coating, completely covering the internal hydroxyapatite particles. This resin layer isolates the hydroxyapatite from the simulated body fluid, preventing it from acting as a nucleation site for inducing mineral deposition, so the coating does not exhibit bioactivity.

[0113] The magnetorheological polishing step included in the process flow of the method takes advantage of the difference in mechanical hardness between the resin binder and hydroxyapatite to achieve selective removal of the surface resin. This process exposes the previously coated hydroxyapatite particles to the outermost surface of the coating. These exposed hydroxyapatite particles can directly interact with calcium and phosphate ions in the simulated body fluid, serving as heterogeneous nucleation cores to induce the formation of a new layer of apatite deposition on their surface. Macroscopically, this process manifests as an increase in the mass per unit area of the sample, thus confirming that surface activation treatment is the key step in making the composite coating biofunctional.

[0114] The curing temperature of the coating is another prerequisite for preserving the bioactivity of hydroxyapatite. The mass increase of the sample after immersion using high-temperature curing is much lower than that of the sample using low-temperature curing. The reason is that the bioactivity of hydroxyapatite depends on its specific chemical composition and crystal structure. At high temperatures, hydroxyapatite will undergo thermal decomposition reactions such as dehydroxylation, which will destroy its chemical structure and thus cause it to lose its biological function as a nucleation substrate for apatite. Using a low-temperature curing process, it is within the stable temperature range of hydroxyapatite, which can completely preserve its chemical structure and bioactivity.

[0115] Test Example 3: Coating chemical stability test

[0116] The purpose of this test example is to quantitatively evaluate the chemical stability of the coatings prepared in Example 1 and Comparative Example 6 in a simulated physiological environment by measuring the total organic carbon (TOC) content in the leaching solution after immersion in physiological saline.

[0117] Experimental steps:

[0118] Preparation of immersion medium: Prepare a 0.9% mass fraction sodium chloride (NaCl) aqueous solution as the immersion medium for physiological saline.

[0119] Sample preparation and placement: Take the coating samples of Example 1 and Comparative Example 6 with dimensions of 10 mm x 10 mm x 2 mm. After rinsing each sample with deionized water, place it in a separate, clean polypropylene (PP) sealed tube.

[0120] Soaking Process: Add 20 mL of normal saline to each sealed tube, ensuring the sample is completely submerged. Place all sealed tubes in a constant temperature oven at 37.0 °C and allow to soak for 28 days.

[0121] Leachate Collection: After the soaking period has elapsed, open the sealed tubes and use a pipette to draw the supernatant from each tube as the leachate sample to be tested, placing it in a clean sample vial.

[0122] TOC Concentration Determination: Turn on the Total Organic Carbon Analyzer (Model: Shimadzu TOC-L) and calibrate using a potassium hydrogen phthalate standard solution. Inject each leachate sample into the analyzer in turn, which converts the organic matter in the sample to carbon dioxide via high-temperature catalytic oxidation, and measures the carbon dioxide concentration using a non-dispersive infrared detector (NDIR), thereby calculating the total organic carbon concentration in the original sample.

[0123] Data Recording: Record the TOC concentration (unit: mg / L) of the leachate corresponding to each sample. Repeat the soaking and testing experiment for each group of coating samples 3 times independently, and record all measured data.

[0124] Experimental Data:

[0125] Table 3: Total Organic Carbon (TOC) Concentration of Leachate from Different Samples

[0126] Sample group Sample No. Leachate TOC concentration (mg / L) Example 1 E3-1 1.1 E3-2 0.8 E3-3 1.3 Comparative Example 6 C6-1 13.7 C6-2 15.2 C6-3 12.9

[0127] By measuring the total organic carbon (TOC) concentration of the leachate from different samples after soaking in normal saline, the influence of the type of coating adhesive on the chemical stability of the coating can be evaluated. The TOC concentration of the leachate from the sample using silicone-modified epoxy resin as the adhesive is significantly lower than that from the sample using unmodified conventional epoxy resin. The only variable in the preparation process of these two samples is the chemical composition of the adhesive.

[0128] The higher concentration of TOC detected in the sample using conventional epoxy resin indicates that organic matter has leached out of the coating in the simulated normal saline environment. The mechanism is that the polymer network formed after the curing of conventional epoxy resin is not chemically stable in an aqueous electrolyte environment, and the incompletely reacted oligomer or small molecule components within it will dissolve out of the coating matrix over time, thus entering the solution.

[0129] The low TOC concentrations exhibited by samples using silicone-modified epoxy resins are attributed to the specific chemical structure of the binder. By introducing methyltriethoxysilane into the epoxy resin system, chemically more stable silicon-oxygen bonds are formed within the cured polymer network. These high-energy bonds increase the crosslinking density and hydrolysis resistance of the entire resin matrix, effectively inhibiting the migration of organic components from the coating into the external environment. This data confirms that the use of silicone-modified epoxy resins as binders is a necessary technical approach to ensure the chemical stability of coatings in physiological environments.

[0130] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A method for treating the bioactive and biocompatible surface of dentures and implants, characterized in that: The following steps are involved: a) Surface pretreatment of the base of dentures or implants; b) applying a layer of composite coating comprising hydroxyapatite particles and a biocompatible resin binder on the pretreated surface of the substrate; c) performing low-temperature thermal curing on the composite coating to form a composite coating; d) Precision polishing the surface of the cured composite coating to selectively remove a portion of the resin adhesive on the surface, so that the hydroxyapatite particles coated inside are exposed on the outermost surface of the coating.

2. The method for treating the bioactive and biocompatible surface of a denture and an implant according to claim 1, wherein: The hydroxyapatite particles in the composite coating are hydroxyapatite surface-modified by a silane coupling agent, and the biocompatible resin adhesive is an organosilicon-modified epoxy resin.

3. The method for treating the bioactive and biocompatible surface of a denture and an implant according to claim 1, wherein: When the substrate is a titanium alloy implant, the surface pretreatment in step a) is to perform anodic electrolysis on the substrate in an electrolyte to form a microscopic concave structure caused by intergranular corrosion on the surface of the substrate.

4. The method for treating the bioactive and biocompatible surface of a denture and an implant according to claim 1, wherein: When the substrate is a zirconium dioxide denture, the surface pretreatment in step a) is to apply a layer of silane coupling agent on the surface of the substrate.

5. The method for treating the bioactive and biocompatible surface of a denture and an implant according to claim 1, wherein: The low temperature heat curing temperature range of c) is 100-150°C.

6. The method for treating the bioactive and biocompatible surface of a denture and an implant according to claim 1, wherein: The precision polishing in step d) adopts a magnetorheological polishing process.

7. A bioactive denture or implant, prepared according to the bioactive and biocompatible surface treatment method for a denture or implant according to any one of claims 1 to 6, characterized in that: include: matrix; A composite coating provided on the surface of the substrate; Wherein, the composite coating is composed of the following components in percentage by weight: Hydroxyapatite particles: 70% to 80%; Biocompatible organosilicon-modified epoxy resin adhesive: 20% to 30%; and the hydroxyapatite particles are exposed on the outermost surface of the composite coating.

8. A bioactive denture or implant according to claim 7, characterized in that: The substrate is a titanium alloy, and the surface of the substrate has a microscopic concave structure between the substrate and the composite coating.

9. A bioactive denture or implant according to claim 7, characterized in that: The substrate is zirconium dioxide, and a silane coupling agent layer is provided between the substrate and the composite coating.

10. A bioactive denture or implant according to claim 7, characterized in that: The hydroxyapatite particles are surface-modified with organic functional groups and have a particle size D50 of 5-15 μm.

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