Application of catechol-alkyl-methacrylate monomer in dentin pretreatment

Abstract

The invention relates to the technical field of dentin pretreatment, in particular to application of a catechol-alkyl-methacrylate monomer in dentin pretreatment. The invention provides an application of a catechol-alkyl-methacrylate monomer (CAM monomer) in dentin pretreatment, the catechol-alkyl-methacrylate monomer has a collagen cross-linking effect and an antibacterial activity effect, and can be copolymerized with a binder, so that a bridging stent of collagen and the binder is formed, and the collagen and the binder can be used for dentin pretreatment. The chemical binding power of the collagen is provided.

Description

Technical Field

[0001] This invention relates to the field of dentin pretreatment technology, and in particular to the application of a catechol-alkyl-methacrylate monomer in dentin pretreatment. Background Technology

[0002] Dental caries is the most common oral disease, affecting over 2.5 billion people worldwide. The primary clinical treatment for caries involves mechanically removing infected tooth structure and using familiar materials to restore the shape and function of the damaged tooth. However, based on modern minimally invasive dental science, caries treatment should prioritize pulp protection, selectively removing caries at the base of the cavity to soften the dentin, and preserving some infected dentin (CAD) for filling. CAD bonding strength and durability are far lower than normal dentin (SD). Therefore, CAD bonding remains a challenging problem in the field of dental bonding.

[0003] The existing resin-dentin bonding system in clinical practice mainly relies on the resin to penetrate into the demineralized collagen scaffold after acid etching and solidify to form a micromechanical interlocking structure to achieve dentin bonding. There is mostly physical tenon-and-mortise retention between the resin and dentin collagen, and there is no effective chemical bonding force. Summary of the Invention

[0004] In view of this, the object of the present invention is to provide an application of catechol-alkyl-methacrylate monomer in dentin pretreatment. The catechol-alkyl-methacrylate monomer has collagen crosslinking and antibacterial activity, and can copolymerize with adhesives to form a bridging scaffold between collagen and adhesive, providing collagen chemical bonding strength.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides the application of catechol-alkyl-methacrylate monomer (CAM monomer) in dentin pretreatment, wherein the catechol-alkyl-methacrylate monomer has the structure shown in Formula 1: Formula 1.

[0006] Preferably, the method of application includes the following steps: The catechol-alkyl-methacrylate monomer and a polar solvent are mixed to obtain a dentin pretreatment agent; After exposing the carious dentin surface of the tooth, it is etched with an acid etchant and then pretreated with the dentin pretreatment agent to obtain pretreated dentin.

[0007] Preferably, the concentration of catechol-alkyl-methacrylate monomer in the dentin pretreatment agent is 1~5 mg / mL; The polar solvent includes one or more of water, anhydrous ethanol, and dimethyl sulfoxide.

[0008] Preferably, the concentration of catechol-alkyl-methacrylate monomer in the dentin pretreatment agent is 5 mg / mL.

[0009] Preferably, the etching agent is phosphoric acid with a mass concentration of 32% to 37%.

[0010] Preferably, the acid etching time is 10-15 seconds.

[0011] Preferably, after the acid etching is completed, the process further includes rinsing and drying. The rinsing agent used is water.

[0012] Preferably, the pretreatment time is 50-60 seconds.

[0013] This invention provides the application of a catechol-alkyl-methacrylate monomer in dentin pretreatment, wherein the catechol-alkyl-methacrylate monomer has the structure shown in Formula 1: Formula 1.

[0014] The catechol-alkyl-methacrylate monomer of this invention can chemically bond with the collagen fibers exposed in the demineralized carious dentin during pretreatment. Subsequently, the hydrophobic benzene ring and alkyl side chain in the catechol-alkyl-methacrylate monomer are located on the collagen surface, forming a hydrophobic structure that is more conducive to resin penetration. Simultaneously, the acrylate groups in the catechol-alkyl-methacrylate monomer can copolymerize with commonly used dental bonding resins, providing additional chemical bonding strength between collagen and resin in cariously infected dentin. Furthermore, the catechol-alkyl-methacrylate monomer also inhibits matrix metalloproteinase activity and cariogenic bacteria activity, thereby effectively improving the bonding effect of carious dentin. The catechol-alkyl-methacrylate monomer is a straight-chain ester structure formed by catechol-derived amines and methacrylates (-COO-). It is suitable for one-step rapid synthesis, low byproduct generation, cost control, and higher material purity, which is beneficial for the safety control of medical materials. Unlike monomers with complex functional structures, the catechol-alkyl-methacrylate monomer has a smaller molecular structure, making it easier to penetrate the dentin-collagen network. The ester bond structure in the catechol-alkyl-methacrylate monomer has high reactivity, making it more likely to have a synergistic effect with the free radical polymerization system commonly found in resin matrices, and can participate in cross-linking reactions more efficiently. Furthermore, unlike other monomers where the main chain is constructed with amide bonds (-CONH-), the straight-chain ester structure of the catechol-alkyl-methacrylate monomer enhances reactivity, adhesive strength, and stability in hydrogel environments, breaking through the conventional structure-function expectations in this field. Attached Figure Description

[0015] Figure 1 Infrared spectra of CAM, cariously infected dentin layer (CAD), and pretreated cariously infected dentin layer; Figure 2 The nuclear magnetic resonance spectra of the type I collagen powder and the solution after the reaction of collagen with CAM are shown. Figure 3 The bonding performance of the resin-dentin bonded specimens obtained in Example 1 and Comparative Examples 1-2; Figure 4 In-situ enzyme profile and enzyme activity analysis of the bonding interface of resin-dentin bonded specimens, and detection of collagen cross-linking ability; Figure 5 This is a diagram showing the antibacterial activity of CAM. Detailed Implementation

[0016] This invention provides the application of a catechol-alkyl-methacrylate monomer in dentin pretreatment, wherein the catechol-alkyl-methacrylate monomer has the structure shown in Formula 1: Formula 1.

[0017] In this invention, the method of application preferably includes the following steps: The catechol-alkyl-methacrylate monomer and a polar solvent are mixed to obtain a dentin pretreatment agent; After exposing the carious dentin surface of the tooth, it is etched with an acid etchant and then pretreated with the dentin pretreatment agent to obtain pretreated dentin.

[0018] The present invention mixes the catechol-alkyl-methacrylate monomer and anhydrous ethanol to obtain a dentin pretreatment agent.

[0019] In this invention, the method for preparing the catechol-alkyl-methacrylate monomer preferably includes the following steps: Under dry and inert gas conditions, 1 eq of 2,3-dihydroxybenzylamine (0.5 g) was dissolved in 10 mL of anhydrous THF and magnetically stirred; 1.1 eq of EDC·HCl and an equal volume of HOBt were added; then 1.1 eq of methacrylate was added, and the reaction was stirred continuously; 2 eq of TEA was added to neutralize the reaction byproducts; the reaction was stirred for 16 h at room temperature or 30 °C; after the reaction was completed, saturated NaHCO3 solution was first added to neutralize the acidic byproducts, followed by 0.1 M hydrochloric acid to neutralize the basic substances, and finally washed with deionized water until the solution was neutral; the organic phase was dried with Na2SO4 and filtered, and concentrated under reduced pressure to obtain the crude product; the crude product was purified by silica gel column chromatography (ethyl acetate / petroleum ether = 1:2) to obtain the target product: catechol-alkyl-methacrylate monomer, which is a yellow transparent oil or solid with a yield of about 60-75%.

[0020] In this invention, the inert gas is preferably nitrogen.

[0021] The present invention does not impose any special limitations on the mixing process; any process known to those skilled in the art can be used.

[0022] In this invention, the concentration of catechol-alkyl-methacrylate monomer in the dentin pretreatment agent is preferably 1-5 mg / mL, more preferably 2-5 mg / mL. In an embodiment of this invention, the concentration of catechol-alkyl-methacrylate monomer in the dentin pretreatment agent can be 5 mg / mL.

[0023] In this invention, the polar solvent preferably includes one or more of water, anhydrous ethanol, and dimethyl sulfoxide. When the polar solvent is two or more of the above-selected substances, this invention does not impose any special limitation on the specific ratio of the substances, and they can be mixed in any ratio. In an embodiment of this invention, the polar solvent may be anhydrous ethanol.

[0024] After obtaining the dentin pretreatment agent, the present invention exposes the cariously infected dentin surface in the tooth, etches it with an acid etchant, and then applies the dentin pretreatment agent for pretreatment to obtain pretreated dentin.

[0025] In this invention, the process of exposing the cariously infected dentin surface of a tooth is not specifically limited, and any process well known to those skilled in the art can be used. In an embodiment of this invention, the process of exposing the cariously infected dentin surface of a tooth can be as follows: first, the caries in the tooth is detected using an X-ray; then, a slow-speed cutting machine is used under running water parallel to the occlusal surface to remove the enamel and expose the CAD surface; finally, the surface is polished with 600-grit sandpaper to obtain a standard smear layer.

[0026] In this invention, the etchant is preferably phosphoric acid with a mass concentration of 32% to 37%, more preferably phosphoric acid with a mass concentration of 34% to 36%. In an embodiment of this invention, the etchant may be phosphoric acid with a mass concentration of 35%.

[0027] In this invention, the acid etching time is preferably 10-15 s, more preferably 13-15 s. In an embodiment of this invention, the acid etching time can be 15 s.

[0028] After the acid etching is completed, the present invention preferably includes rinsing and drying in sequence; the rinsing agent used is preferably water, and the rinsing time is preferably 20-30 seconds, more preferably 25-30 seconds. In an embodiment of the present invention, the rinsing time can be 30 seconds.

[0029] In this invention, the moisture removal is preferably performed by using filter paper to remove excess moisture from the dentin surface.

[0030] In this invention, the pretreatment time is preferably 50-60 s, more preferably 55-60 s. In an embodiment of this invention, the pretreatment time can be 60 s.

[0031] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0032] Example 1 A dentin pretreatment agent with a concentration of 5 mg / mL was obtained by mixing catechol-alkyl-methacrylate monomer and anhydrous ethanol. Freshly extracted carious third molars were collected with the patient's informed consent, stored in a 5% chloramine-T solution at 4°C, and used within one month. Using X-rays, the carious third molar was located in the middle 1 / 3 of the extracted tooth in the occlusal dentin. A slow-speed cutter was used to remove the enamel parallel to the occlusal surface under running water to expose the CAD plane. The demineralized dentin surface was then obtained by polishing with 600-grit sandpaper. The demineralized dentin surface was etched with a 35% phosphoric acid etchant for 15 seconds, rinsed with running water for 30 seconds, and excess water was absorbed with filter paper. The dentin pretreatment agent was then applied for 60 seconds, and the surface moisture was absorbed again with filter paper. Finally, the adhesive (trade name 3M ESPE Adper) was applied according to the manufacturer's instructions. TM Single Bond 2) and cured using Z250 resin (3M ESPE Filtek). TM Z250) deposited a 6mm thick filler and cured it to obtain resin-dentin bond specimens; then divided into an immediate group (stored in distilled water at 37℃ for 24 hours) and an aging group (1000 cycles of cold and heat treatment (cold treatment at 5℃ for 1 min, then heat treatment at 55℃ for 1 min)).

[0033] Comparative Example 1 Control group: Refer to Example 1, except that no pretreatment is performed; after acid etching, the obtained resin-dentin bond specimens are also divided into immediate group (stored in distilled water at 37°C for 24 hours) and aging group (1000 cycles of hot and cold treatment (cold treatment at 5°C for 1 min, then heat treatment at 55°C for 1 min)).

[0034] Comparative Example 2 Referring to Example 1, the difference is that the decayed tooth is replaced with an intact tooth, and in the intact tooth located in the 1 / 3 of the extracted tooth in the dentin of the occlusal surface, the enamel is removed by a slow cutting machine under running water parallel to the occlusal surface to expose the SD surface, and the normal dentin layer is obtained by polishing with 600-grit sandpaper. The normal dentin layer was etched with a 35% phosphoric acid etchant for 15 seconds, rinsed with running water for 30 seconds, and excess surface moisture was absorbed with filter paper. The dentin pretreatment agent was then applied for 60 seconds, and the surface moisture was absorbed again with filter paper. The adhesive (Single Bond 2, 3M) was applied and cured according to the manufacturer's instructions. A 6mm thick filling was then deposited using Z250 resin (Filtek Z250, 3M ESPE) and cured to obtain a resin-dentin bond specimen. The specimen was then divided into an immediate group (stored in distilled water at 37°C for 24 hours) and an aging group (1000 cycles of cold and heat treatment (cold treatment at 5°C for 1 minute, followed by heat treatment at 55°C for 1 minute)).

[0035] Test case For ease of detection, infrared spectroscopy was performed on 1 mm thick cariously infected dentin and normal dentin sections (n=6 repetitions per group) following the pretreatment process described in Example 1. The results are shown in the figure. Figure 1 ( Figure 1 The image shows the infrared spectra of the CAM, the cariously infected dentin layer (CAD), and the pretreated cariously infected dentin layer. Figure 1 It can be seen that the characteristic -NH, amide I, amide II and amide III bands of dentin collagen were found in both CAD and the pretreated carious dentin layer. The amide I band (amide I, 1639nm), amide II band (amide II, 1540nm) and amide III band (amide III, 1238nm) of the pretreated carious dentin layer all showed a blue shift. The characteristic peaks of CAM at 653nm (-OH) and 1741nm (C=O) appeared, indicating that CAM was successfully grafted onto the collagen surface. Type I collagen powder (CLP-01, Koken Co. Ltd., Japan) was dissolved in a D2O buffer solution containing 50 mM d4-acetic acid, 150 mM NaCl, 5 mM CaCl2, and 0.02 wt% NaN3 (pD = 4.0, adjusted with NaOD) to obtain a saturated collagen solution. This saturated collagen solution was diluted 4-fold with a buffer solution (D2O buffer solution containing 50 mM d4-acetic acid, 150 mM NaCl, 5 mM CaCl2, and 0.02% NaN3) to reduce viscosity, yielding a dilution buffer. The CAM monomer was added to the dilution buffer solution to obtain a solution of collagen reacted with CAM at a concentration of 5 mg / mL. The type I collagen powder and the solution of collagen reacted with CAM (CAM + type I collagen) were analyzed by nuclear magnetic resonance (NMR) using a 600 MHz spectrometer with an ultra-low temperature probe (Bruker BioSpin Corporation, Billerica, USA). Figure 2 The nuclear magnetic resonance spectra of the type I collagen powder (A) and the solution (B) after the reaction of collagen with CAM are given by [the relevant authority / organization]. Figure 2 It can be seen that 6.7-7.5 ppm corresponds to the hydrogen atoms of benzene rings a, b, and c in the spectrum, and 5.4-6.1 ppm corresponds to the acrylate group d in the spectrum, which further verifies that CAM successfully binds to collagen. A slow-speed cutting machine was used to cut cross-sectional areas of 1 mm from Examples 1 and Comparative Examples 1 and 2. 2Resin-dentin bond specimens (n=10 repetitions within each group) were tested and recorded at fracture load using a micro tensile testing machine (tensile rate of 0.5 mm / min) while the specimens were kept moist (EZ-TEST 500 N, Shimadzu Co., test results are the average plus standard deviation of repeated experiments). Resin-dentin bond specimens from Examples 1 and 2 were cut using a slow-speed cutter, approximately 1 mm perpendicular to the bonding interface. Hydrophobic nail polish was applied to the area 1 mm above and below the bonding interface. After drying, the specimens were immersed in a 50 wt% silver ammonium nitrate solution for 24 h in the dark, developed for 8 h, fixed for 8 h, dried, sputtered with gold, and the nano-permeability of the bonding interface was observed under a scanning electron microscope. Figure 3 The bonding performance of the resin-dentin bonded specimens obtained in Examples 1 and 1-2 is shown in Figure 1. A represents the micro-tensile bond strength of the resin-dentin bonded specimens obtained in Examples 1 and 1-2; B represents the nano-leakage rate of the resin-dentin bonded specimens obtained in Examples 1 and 1-2; and C represents the CLSM diagram of the resin-dentin bonded specimens obtained in Examples 1 and 1-2 (wherein, normal dentin corresponds to Example 2, cariously infected dentin corresponds to Example 1, and cariously infected dentin + CAM corresponds to Example 1; the scale bar in the lower right corner of the CLSM diagram is 50 μm). Figure 3 As shown in A, the bond strength of the immediate group in Comparative Example 1 decreased by approximately 44% compared to the immediate group in Comparative Example 2, while the bond strength of the immediate group in Example 1 showed a significant improvement compared to the immediate group in Comparative Example 1. The bond strength of all aging groups decreased compared to the immediate groups, with the aging group in Example 1 showing the least decrease in bond strength compared to the immediate groups. Figure 3 As shown in B and C, the immediate group in Comparative Example 2 had the least amount of nano-leakage, while the immediate group in Comparative Example 1 had the most amount of nano-leakage, approximately 60%. The immediate group in Example 1 had less nano-leakage than the immediate group in Comparative Example 1. After the aging treatment of hot and cold cycles, the nano-leakage of each group increased. The nano-leakage of the aging group in Example 1 was significantly lower than that of the aging group in Comparative Example 1, and similar to that of the immediate group in Comparative Example 1. Resin-dentin bond specimens from Examples 1 and 1-2, approximately 1 mm perpendicular to the bonding interface, were cut using a slow-speed cutter. The specimens were then subjected to gradient sanding (320, 600, 1200, 2000, 4000, and 5000 grit) under running water, shaken with deionized water for 5 minutes, and dried with filter paper. The treated specimens were placed on glass slides, and 50 μL of collagenase activity indicator was added to immerse the surface. The slides were then covered and incubated at 37°C in the dark and at 100% humidity for 48 hours. The surface dye was washed off with deionized water and the specimens were air-dried. The endogenous enzyme activity at the bonding interface was detected using a laser confocal microscope (CLSM). The collagen cross-linking was assessed using sodium dodecyl sulfate polyacrylamide gel (SDS-PAGE). All solutions (the experimental kit (Beyotime SDS-PAGE gel rapid preparation kit) and the dentin pretreatment agent described in Example 1) were stored at room temperature for 24 hours to obtain the modified cross-linking solution. The groups were: marker group (known marker bands, 10-200 kDa), control group (non-crosslinked solution), positive control group (commercial glutaraldehyde solution, prepared at 5% (Glutaricdialdehyde, GD)) and CAM group (dentin pretreatment agent as described in Example 1). Cross-linking solution preparation: Solution for each experimental group (CAM group and positive irradiation group): 3.52 mg / mL collagen solution = 1:1; Non-crosslinked solution (control group): Deionized water: 3.52 mg / mL collagen solution = 1:1; Mix 50 μL of each cross-linking solution with 10 μL of SDS protein loading buffer, heat at 98 °C for 10 min, load 10 μL of each sample for electrophoresis, first use a constant voltage of 80 V for about 30 min, after the indicator marker enters, adjust the voltage to 100 V until it reaches the bottom of the gel, after electrophoresis, stain with Coomassie blue for 2 h, destain for 1 h, and take pictures for recording and analysis.

[0036] in Figure 4 The results of the CAM bonding interface stability factor test are shown, where A is a representative image of the in-situ enzyme spectrum of the resin-dentin bonding interface for each group, B is the statistical result of the converted endogenous enzyme activity of the in-situ enzyme spectrum of the resin-dentin bonding interface for each group, and C is the collagen cross-linking effect of CAM; Figure 4 As shown in A, in normal dentin, the bonding interface exhibits green fluorescence representing enzyme activity after acid etching. In cariously infected dentin, the green fluorescence at the bonding interface is significantly stronger than in normal dentin, while in cariously infected dentin treated with CAM, the green fluorescence at the bonding interface is significantly reduced. Figure 4As shown in B, statistical analysis of the green fluorescence intensity at the bonding interface using in-situ enzyme chromatography revealed that the endogenous enzyme activity was highest after acid etching of cariously infected dentin, followed by normal dentin with lower enzyme activity than cariously infected dentin. After CAM treatment, the endogenous enzyme activity of cariously infected dentin was the lowest. Figure 4 As shown in C, the collagen in the untreated blank control group showed multiple protein imprints in the lanes, while the collagen in the CAM group and the positive control glutaraldehyde group underwent cross-linking, and the molecular weight increased significantly beyond the molecular sieve pores, resulting in no protein imprints in the lanes, proving that collagen cross-linking occurred.

[0037] Antibacterial activity test: Frozen Streptococcus mutans (ATCC25175) was cultured in an anaerobic incubator at 37°C for 24 hours. Single colonies were then inoculated onto sterile BHI agar plates and anaerobically cultured at 37°C for another 24 hours. The bacterial culture was then diluted to 0.5 MAC (1×10⁻⁶) using BHI liquid medium. 8 (CFU / mL), then further serially diluted 100-fold to 1×10⁻⁶. 6 CFU / mL, the obtained Streptococcus mutans culture medium is used for later use; Add CAM at a concentration of 5 mg / mL to 1×10 6 In BHI culture medium with CFU / mL, the control group used the bacterial suspension directly without any addition. The suspension was anaerobically cultured at 37℃ with shaking for 24 h. Then, 100 μl of the cultured bacterial suspension was taken, diluted 10 times with BHI culture medium, and inoculated onto BHI agar plates. After 48 hours of culture, the colony count (CFU) was counted.

[0038] Sterilized glass slides were placed at the bottom of a 6-well plate, and 1 mL of the above-mentioned Streptococcus mutans culture medium and CAM solution with a concentration of 5 mg / mL were added respectively. The plates were cultured under anaerobic conditions at 37℃ for 24 h to form plaque biofilms. Commercial glutaraldehyde solution was added to prepare a 2.5% fixation solution for 12 h. The plates were dehydrated by an ethanol gradient, dried and sputter-coated with gold, and the morphology of the plaque biofilms was observed under a scanning electron microscope (FE-SEM). Add 500 μL of live / dead bacteria staining reagent (LIVE / DEADBacLigh, l7012, Molecular Probes, USA) to each well of the above-mentioned cultured plaque biofilm, then cover the dentin specimen (resin-dentin bonded specimens obtained in Example 1 and Comparative Examples 1-2), incubate at room temperature in the dark for 15 min, rinse the surface with PBS to remove excess dye, and observe the bacteria on the surface of the dentin specimen using a laser confocal microscope; Figure 5The images show the antibacterial activity of CAM, where A is a representative image of colony-forming units (CFU), B is the statistical results of CFU, C is the bacterial morphology observed under a scanning electron microscope, D is a representative image of live and dead bacteria stained under laser confocal microscopy, and E is the statistical results of live and dead bacteria staining. Figure 5 As shown in A and B, in the CFU counting experiment, the CFU in the CAM group was significantly reduced by two orders of magnitude compared to the control group (bacteria were cultured in the culture medium without any reagents). Figure 5 As shown in C, the bacteria in the control group were mostly plump and structurally intact, while in the CAM group, the bacterial accumulation was reduced, and bacterial swelling and death were observed; from Figure 5 As shown in D, the control group mainly consisted of live green bacteria with a small amount of dead red bacteria, while the CAM group was mainly composed of dead red bacteria. Figure 5 The E value indicates that the ratio of dead to live bacteria was significantly higher than that of the control group. This suggests that CAM has a significant inhibitory effect on Streptococcus mutans.

[0039] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. The application of a catechol-alkyl-methacrylate monomer in dentin pretreatment, characterized in that, The catechol-alkyl-methacrylate monomer has the structure shown in Formula 1: Formula 1.

2. The application as described in claim 1, characterized in that, The method of application includes the following steps: The catechol-alkyl-methacrylate monomer and a polar solvent are mixed to obtain a dentin pretreatment agent; After exposing the carious dentin surface of the tooth, it is etched with an acid etchant and then pretreated with the dentin pretreatment agent to obtain pretreated dentin.

3. The application as described in claim 2, characterized in that, The concentration of catechol-alkyl-methacrylate monomer in the dentin pretreatment agent is 1~5 mg / mL; The polar solvent includes one or more of water, anhydrous ethanol, and dimethyl sulfoxide.

4. The application as described in claim 3, characterized in that, The concentration of catechol-alkyl-methacrylate monomer in the dentin pretreatment agent is 5 mg / mL.

5. The application as described in claim 2, characterized in that, The etching agent is phosphoric acid with a mass concentration of 32% to 37%.

6. The application as described in claim 2 or 5, characterized in that, The acid etching time is 10-15 seconds.

7. The application as described in claim 2, characterized in that, After the acid etching is completed, the process also includes rinsing and drying. The rinsing agent used is water.

8. The application as described in claim 2, characterized in that, The preprocessing time is 50-60 seconds.

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