Preparation method and application of a nano-removable coating that can isolate saliva contamination and improve the bonding strength of zirconia restorations

Abstract

A method for preparing and applying a nano-removable coating that can isolate saliva contamination and improve the bonding strength of zirconia restorations. The method includes the following steps: (1) cleaning the substrate material; (2) preparing a tannic acid solution and a ferric chloride hexahydrate solution; (3) sequentially adding the ferric chloride hexahydrate solution and tannic acid solution to the cleaned substrate material, vortexing, adjusting the pH value, continuing vortexing, washing, and drying to obtain a nano-removable coating that can isolate saliva contamination and improve the bonding strength of zirconia restorations. The MPN coating provided by this invention can effectively isolate the interaction between proteins and the zirconia substrate material, overcoming saliva contamination caused during restoration trial. It can be pre-coated before trial and removed before clinical bonding. Furthermore, the bonding durability of zirconia restorations treated with this MPN coating is close to that of zirconia restorations treated with cleaning agents, and superior to zirconia restorations treated with Ivoclean cleaning agent.

Description

Technical Field

[0001] This invention relates to a method for preparing and applying a nano-removable coating that can isolate oral saliva, blood and other contaminants and improve the bonding strength of zirconia restorations, belonging to the field of oral ceramic coating technology. Background Technology

[0002] In recent years, zirconia ceramics have been widely used in the fabrication of various dental prostheses, including crowns, fixed bridges, adhesive bridges, inlays, veneers, implant abutments, and orthodontic brackets, due to their excellent aesthetic properties, good biocompatibility, and ultra-high mechanical strength. However, unlike glass ceramics, the low bonding strength of zirconia has always been a major challenge for dentists. Firstly, because zirconia is a polycrystalline ceramic and does not contain a glassy phase, it is difficult to perform hydrofluoric acid etching like glass ceramics. Secondly, zirconia has high hardness and density, limiting surface roughening methods and making it difficult to form a micromechanically interlocking bonding surface with the adhesive. Finally, the chemical inertness of zirconia makes it difficult to chemically bond with organosilanes.

[0003] Currently, the most widely accepted treatment methods are sandblasting to increase the surface roughness of zirconia, thereby improving the mechanical retention force of the bond, and using resin bonding systems containing phosphate ester monomers to form a chemical bond with the hydroxyl groups on the zirconia surface. In addition, during clinical bonding, proper moisture and contamination prevention are essential; otherwise, the bond strength of the restoration will be significantly reduced, affecting its final durability. However, a trial fitting of the restoration must be performed intraorally before bonding to check its fit. This inevitably leads to contamination of the bonding surface by various contaminants, including saliva, blood, gingival crevicular fluid, and silicone rubber indicators, with saliva contamination having the greatest impact. Saliva is 99% water, and in addition, it contains various organic substances (such as salivary proteins, bacteria, food debris, and enzyme molecules) and inorganic components (minerals). During clinical trials, salivary proteins can form a nanofilm on the bonding surface of the restoration within seconds, reducing the free energy of the bonding surface and occupying the binding sites between zirconia and the resin adhesive. This affects the penetration, curing, and chemical bonding of the resin adhesive at the bonding surface, thereby reducing the bonding strength and durability of zirconia. Scanning electron microscopy (SEM) revealed a protein film on the surface of zirconia contaminated with saliva. XPS elemental analysis of the bonding surface after saliva contamination showed a significant increase in C and N elements and a decrease in Zr. Simultaneously, shear strength (SBS) testing showed a significant immediate decrease in the bonding strength of zirconia after saliva contamination, with an even more pronounced decrease after aging.

[0004] Therefore, scholars both domestically and internationally have conducted extensive research on the impact of saliva contamination on the bonding strength of zirconia restorations. Existing methods mainly focus on surface physical treatment (sandblasting) and chemical cleaning. Chemical cleaning primarily involves using the chemical cleaner Ivoclean or the routine clinical treatment of wiping with alcohol. Ivoclean is a purple, strongly alkaline, supersaturated solution, mainly composed of spherical zirconia particles, sodium hydroxide, polyethylene glycol, water, and pigments. While this product can largely remove the impact of saliva contamination on zirconia bonding, residual small zirconia particles can reduce bonding durability. Furthermore, a single bottle of this product costs nearly 500 yuan, with only 5g per bottle, making its usage cost relatively high. Routine clinical treatment of wiping with alcohol does not effectively remove the salivary protein film on the bonding surface, thus failing to improve bonding strength. The above methods focus on how to remove saliva contamination after it occurs, thus affecting the bonding strength of zirconia restorations. The purpose of this invention is to find a simple, efficient, and low-cost method to construct a protective barrier on the zirconia bonding surface, fundamentally isolating it from saliva contamination. Therefore, there is an urgent need to develop a nano-removable coating material that can isolate saliva contamination and improve the bonding strength of zirconia restorations. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a method for preparing and applying a nano-removable coating that can isolate saliva contamination and improve the bonding strength of zirconia restorations.

[0006] The technical solution of the present invention is as follows:

[0007] A method for preparing a removable nano-coating that can isolate saliva contamination and improve the adhesive strength of zirconia restorations includes the following steps:

[0008] (1) Clean the substrate material;

[0009] (2) Prepare tannic acid (TA) solution and ferric chloride hexahydrate (FeCl3·6H2O) solution;

[0010] (3) Add ferric chloride hexahydrate (FeCl3·6H2O) solution and tannic acid (TA) solution to the cleaned substrate material in sequence. Vortex for 20-60s after each addition, adjust the pH value to 7-9, continue vortexing for 20-60s, clean and dry, and obtain a nano-removable coating that can isolate saliva contamination and improve the bonding strength of zirconia restoration.

[0011] According to a preferred embodiment of the present invention, in step (1), the substrate material is a zirconium oxide repair body.

[0012] According to a preferred embodiment of the present invention, in step (1), the cleaning method is as follows: add anhydrous ethanol to the substrate material, ultrasonically clean for 10 minutes, then replace with deionized water and continue ultrasonic cleaning for 5 minutes.

[0013] According to a preferred embodiment of the present invention, in step (2), the concentration of the tannic acid (TA) solution is 3-4 mg / mL.

[0014] More preferably, the concentration of the tannic acid (TA) solution is 3.2 mg / mL.

[0015] According to a preferred embodiment of the present invention, in step (2), the concentration of the ferric chloride hexahydrate (FeCl3·6H2O) solution is 0.75 to 1 mg / mL.

[0016] More preferably, the concentration of the ferric chloride hexahydrate (FeCl3·6H2O) solution is 0.8 mg / mL.

[0017] According to a preferred embodiment of the present invention, in step (3), the volume ratio of the tannic acid (TA) solution and the ferric chloride hexahydrate (FeCl3·6H2O) solution is 1:1, and the mass concentration ratio is 4:1.

[0018] According to a preferred embodiment of the present invention, in step (3), the pH is adjusted using 0.1M NaOH with pH=13.

[0019] The present invention also provides a nano-removable coating prepared by the above method that can isolate saliva contamination and improve the bonding strength of zirconia restorations.

[0020] The above-mentioned nano-removable coating, which can isolate saliva contamination and improve the bonding strength of zirconia restorations, is applied in oral restoration.

[0021] According to a preferred embodiment of the present invention, the application specifically includes:

[0022] Before clinical trial fitting, a nano-removable coating that can isolate saliva contamination and improve the bonding strength of the zirconia restoration was prepared according to the above method, resulting in a restoration pre-coated with MPN (Fe-TA) coating;

[0023] The restorations pre-coated with MPN (Fe-TA) were tried on in the oral cavity to check their fit;

[0024] After the clinical trial fitting and before bonding, the restoration pre-coated with MPN (Fe-TA) is placed in an HCl solution and sonicated for 20-60 seconds to adjust the pH to 1-2. Then it is placed in a NaOH solution to neutralize excess acid on the surface and remove residual protein. After cleaning and drying, the restoration with the MPN (Fe-TA) coating removed is then used for oral restoration.

[0025] More preferably, the concentration of the HCl solution is 0.1 mol / L and the pH is 1; the concentration of the NaOH solution is 0.1 mol / L and the pH is 13.

[0026] Technical features of the present invention:

[0027] This invention utilizes a one-step assembly method to perform aqueous deposition of a natural polyphenol tannic acid (TA) and a metal ion complex, ferric chloride hexahydrate (FeCl3·6H2O), onto a zirconia restoration at room temperature, forming a thin film coating of approximately 10 nm within seconds. This film coating is initiated by polyphenol adsorption, followed by inorganic cross-linking of metal ions, and guided by pH-dependent multivalent coordination bonding.

[0028] The specific mechanisms of coating assembly and removal are as follows: When pH is less than 2, the mixture is colorless. At low pH, a large number of hydroxyl groups of TA (binding sites with metal ions) are protonated, and Fe-TA crosslinking is unstable, forming a single-sided complex, leading to membrane decomposition (coating removal mechanism); When pH is greater than 3 and less than 6, the mixture is blue, Fe-TA forms a dihedral complex, and the membrane is relatively unstable; When pH is greater than 7, the mixture is red, Fe-TA forms a trihedral complex, and the membrane has high stability and high mechanical properties (coating stabilization mechanism).

[0029] Natural polyphenol tannic acid (TA) binds to salivary proteins through hydrophobic interactions and hydrogen bonds. This invention utilizes an MPN (Fe-TA) coating as a barrier to effectively isolate the interaction between proteins and zirconium oxide. Subsequently, taking advantage of the pH dependence of the complex of natural polyphenol TA and trivalent Fe ions, it is immersed in a hydrochloric acid solution. The nano-coating degrades as the pH decreases. Then, excess acid is neutralized by alkali and residual proteins are removed, leaving a clean restoration surface for subsequent oral restoration.

[0030] The beneficial effects of this invention are as follows:

[0031] 1. This invention utilizes natural polyphenol tannic acid (TA) and the metal ion complex ferric chloride hexahydrate (FeCl3·6H2O) to prepare a nano-removable coating on a substrate material in a one-step assembly process. This coating isolates saliva contamination and improves the adhesive strength of zirconia restorations. The MPN (Fe-TA) coating effectively isolates the interaction between proteins and zirconia, overcoming saliva contamination during restoration fitting and fundamentally eliminating the problem of saliva contamination affecting zirconia adhesion. Furthermore, this MPN (Fe-TA) coating exhibits excellent degradation properties, allowing for pre-application before fitting and removal before clinical bonding. Its effectiveness is comparable to that of Ivoclean cleaning agent. Simultaneously, the adhesive durability of zirconia restorations treated with this MPN (Fe-TA) coating is close to that of zirconia restorations without saliva contamination, and superior to zirconia restorations treated with Ivoclean cleaning agent.

[0032] 2. The nano-removable coating provided by this invention, which isolates saliva contamination and improves the bonding strength of zirconia restorations, contains abundant hydroxyl groups (metal ion chelating agents), which can reduce metalloenzyme activity, extract metal ions needed by microorganisms, and inhibit bacterial growth. Simultaneously, the multi-functional phenolic groups of tannic acid (TA) can disrupt the stability and integrity of cell membranes, and TA can reduce the activity of glucosyltransferase GTF (GTF promotes the adhesion of Streptococcus, the most abundant bacteria in the oral cavity's natural flora, to the tooth surface), thereby inhibiting bacterial adhesion and achieving an antibacterial effect.

[0033] 3. The raw materials of this invention are low in cost, the preparation method is simple, and it is easier to promote quickly; the coating has good biocompatibility and is safe during oral trial; the coating is thin and does not affect the placement of the prosthesis. Attached Figure Description

[0034] Figure 1 A schematic diagram illustrating saliva contamination during intraoral fitting of a zirconia restoration and the application of the coating.

[0035] Figure 2 Macroscopic color changes and scanning electron microscope images of zirconia ceramic blocks after sandblasting, zirconia restorations pre-coated with MPN (Fe-TA) coating, and zirconia restorations with MPN (Fe-TA) coating removed;

[0036] Figure 2 In the image: A shows the macroscopic color change during the successful coating synthesis and removal process; B shows a 5000x scanning electron microscope (SEM) image of the zirconia ceramic block after sandblasting; C shows a 5000x SEM image of the MPN(Fe-TA) coating after preparation; D shows a 20000x SEM image of the MPN(Fe-TA) coating; E shows a 5000x SEM image of the zirconia restoration after the MPN(Fe-TA) coating has been removed.

[0037] Figure 3 The Fourier transform infrared (FT-IR) spectra of the following zirconia restorations are: sandblasted zirconia blocks, zirconia restorations pre-coated with MPN (Fe-TA) coating, and zirconia restorations with MPN (Fe-TA) coating removed.

[0038] Figure 4 The results of X-ray photoelectron spectroscopy (XPS) surface elemental analysis of the sandblasted zirconia ceramic block, the zirconia restoration pre-coated with MPN (Fe-TA) coating, and the zirconia restoration with the MPN (Fe-TA) coating removed.

[0039] Figure 5 The results of water contact angle hydrophilicity test (WCA) are as follows: zirconia ceramic block after sandblasting, zirconia restoration with MPN (Fe-TA) coating pre-coated, and zirconia restoration with MPN (Fe-TA) coating removed.

[0040] Figure 6 Fourier transform infrared (FT-IR) spectra of zirconia restorations with MPN (Fe-TA) coating removed, zirconia restorations with MPN (Fe-TA) coating after saliva treatment, zirconia restorations with MPN (Fe-TA) coating pre-coated, zirconia restorations after saliva treatment, and zirconia blocks after sandblasting.

[0041] Figure 7 Immunofluorescence analysis of proteins isolated by MPN (Fe-TA) coating (BSA-FITC).

[0042] Figure 8 The results are for the antibacterial test of the MPN(Fe-TA) coating.

[0043] Figure 9 This is a scanning electron microscope image of the MPN(Fe-TA) coating after an antibacterial test.

[0044] Figure 10 The results show the immediate bond strength of different groups of zirconia restorations.

[0045] Figure 11 The results show the aging bond strength of different groups of zirconia restorations.

[0046] Figure 12 The fracture mode analysis results and typical scanning electron microscope images of fracture surfaces of different groups of zirconia restorations are presented.

[0047] Figure 13 Scanning electron microscope images of different groups of zirconia restorations.

[0048] Figure 14 The results of surface elemental analysis of different groups of zirconia restorations using X-ray photoelectron spectroscopy (XPS). Detailed Implementation

[0049] The embodiments of the present invention are described in detail below. These embodiments are implemented based on the technical solution of the present invention, and provide detailed implementation methods and specific operation processes. However, the scope of protection of the present invention is not limited to the following embodiments.

[0050] The raw materials and equipment used in the examples were all commercially available products, and the saliva used was collected from normal healthy people on an empty stomach in the morning.

[0051] Example 1

[0052] A method for preparing a removable nano-coating that can isolate saliva contamination and improve the adhesive strength of zirconia restorations includes the following steps:

[0053] (1) Place the sandblasted zirconia ceramic block with a size of 10mm*10mm*2mm into a 50ml centrifuge tube, add 10ml of anhydrous ethanol, sonicate for 10min, then replace with 10ml of deionized water and continue sonicating for 5min to obtain a thoroughly cleaned zirconia ceramic block.

[0054] (2) Prepare a tannic acid (TA) solution with a concentration of 3.2 mg / ml and a ferric chloride hexahydrate (FeCl3·6H2O) solution with a concentration of 0.8 mg / ml;

[0055] (3) After drying the pretreated zirconia ceramic block, place it into a 50ml centrifuge tube, add 10ml of FeCl3·6H2O solution and 10ml of TA solution in sequence, vortex for 60s after each addition, then add 1.5ml of 0.1M NaOH solution to the centrifuge tube to adjust the pH of the mixed solution from 2.5 to 8, continue vortexing for 60s, wash and dry, and obtain a nano-removable coating (MPN(Fe-TA) coating) that can isolate saliva contamination and improve the bonding strength of zirconia restoration.

[0056] Example 2

[0057] A method for preparing a removable nano-coating that can isolate saliva contamination and improve the adhesive strength of zirconia restorations includes the following steps:

[0058] (1) Place the sandblasted zirconia ceramic block with a size of 10mm*10mm*2mm into a 50ml centrifuge tube, add 10ml of anhydrous ethanol, sonicate for 10min, then replace with 10ml of deionized water and continue sonication for 5min to obtain the pretreated zirconia ceramic block.

[0059] (2) Prepare a tannic acid (TA) solution with a concentration of 3 mg / ml and a ferric chloride hexahydrate (FeCl3·6H2O) solution with a concentration of 0.5 mg / ml;

[0060] (3) After drying the pretreated zirconia ceramic block, place it into a 50ml centrifuge tube, add 10ml of FeCl3·6H2O solution and 10ml of TA solution in sequence, vortex for 40s after each addition, then add 1.5ml of 0.1M NaOH solution to adjust the pH value to 8, continue vortexing for 40s, wash and dry, and obtain a nano-coating that can isolate saliva contamination and improve adhesion strength.

[0061] Example 3

[0062] A method for preparing a removable nano-coating that can isolate saliva contamination and improve the adhesive strength of zirconia restorations includes the following steps:

[0063] (1) Place the sandblasted zirconia ceramic block with a size of 10mm*10mm*2mm into a 50ml centrifuge tube, add 10ml of anhydrous ethanol, sonicate for 10min, then replace with 10ml of deionized water and continue sonication for 5min to obtain the pretreated zirconia ceramic block.

[0064] (2) Prepare a tannic acid (TA) solution with a concentration of 4 mg / ml and a ferric chloride hexahydrate (FeCl3·6H2O) solution with a concentration of 1 mg / ml.

[0065] (3) After drying the pretreated zirconia ceramic block, place it into a 50ml centrifuge tube, add 10ml of FeCl3·6H2O solution and 10ml of TA solution in sequence, vortex for 20s after each addition, then add 1.5ml of 0.1M NaOH solution to adjust the pH value to 8, continue vortexing for 20s, and after washing and drying, the color of the zirconia ceramic block can be seen to change from white to purple, thus obtaining a nano-coating that can isolate saliva contamination and improve the bonding strength.

[0066] Example 4

[0067] A schematic diagram illustrating saliva contamination during intraoral fitting of zirconia restorations and the application of the coating is shown below. Figure 1 As shown, this embodiment simulates saliva contamination during intraoral fitting.

[0068] A nano-removable coating that can isolate saliva contamination and improve the bonding strength of zirconia restorations was prepared according to the method described in Example 1, resulting in zirconia restorations pre-coated with MPN (Fe-TA) coating;

[0069] The zirconia restoration pre-coated with MPN(Fe-TA) was placed in a 50ml centrifuge tube, 10ml of freshly collected saliva was added, the ceramic block was immersed for 60s, then rinsed with water and dried to obtain the saliva-treated MPN(Fe-TA) coated zirconia restoration.

[0070] After saliva treatment, the MPN(Fe-TA) coated zirconia restorations were placed in a 50ml centrifuge tube, and 10ml of 0.1mol / L HCl solution (pH=1) was added. The tubes were sonicated for 60s, then rinsed with water to remove the HCl. Subsequently, the restorations were placed in a 0.1M NaOH solution (pH=13) to neutralize excess acid and remove residual protein. Finally, the tubes were rinsed and dried to obtain zirconia restorations with the MPN(Fe-TA) coating removed. This group was designated as the coating group (pre-coated group).

[0071] Comparative Example 1

[0072] A sandblasted zirconia ceramic block measuring 10mm*10mm*2mm was placed in a 50ml centrifuge tube, followed by the addition of 10ml of anhydrous ethanol. The block was ultrasonically cleaned for 10 minutes, then replaced with 10ml of deionized water and ultrasonically cleaned for another 5 minutes to obtain a thoroughly cleaned zirconia restoration, which was designated as the zirconia cleaned group (cleaned group).

[0073] Comparative Example 2

[0074] A sandblasted zirconia ceramic block measuring 10mm*10mm*2mm was placed in a 50ml centrifuge tube, and 10ml of freshly collected saliva was added. The block was immersed for 60 seconds, then rinsed with water and dried to obtain a saliva-treated zirconia restoration, which was designated as the saliva-contaminated group.

[0075] Comparative Example 3

[0076] A 10mm*10mm*2mm sandblasted zirconia ceramic block was placed in a 50ml centrifuge tube, followed by the addition of 10ml of anhydrous ethanol. The tube was ultrasonically cleaned for 10 minutes, then replaced with 10ml of deionized water and ultrasonically cleaned for another 5 minutes to obtain a thoroughly cleaned zirconia restoration. After rinsing and drying, the restoration was immersed in 10ml of freshly collected saliva for 60 seconds, then removed, rinsed, and dried. Finally, it was wiped with a cotton ball soaked in 75% ethanol (clinically used). This group of zirconia restorations was designated as the alcohol-wiped group.

[0077] Comparative Example 4

[0078] A 10mm*10mm*2mm sandblasted zirconia ceramic block was placed in a 50ml centrifuge tube, followed by the addition of 10ml of anhydrous ethanol. The tube was ultrasonically cleaned for 10 minutes, then replaced with 10ml of deionized water and ultrasonically cleaned for another 5 minutes to obtain a thoroughly cleaned zirconia restoration. After rinsing and drying, the restoration was immersed in 10ml of freshly collected saliva for 60 seconds, then removed, rinsed, and dried. It was then cleaned with the commercial chemical cleaner Ivoclean. According to the instructions, the purple liquid was evenly applied to the bonding surfaces with a small brush for 20 seconds, followed by rinsing with water for 40 seconds and drying. This resulted in the Ivoclean-cleaned zirconia restoration, designated as the Ivoclean group.

[0079] Experimental Example 1

[0080] 1. Macroscopic color observation and scanning electron microscopy were performed on the sandblasted zirconia ceramic block (10mm*10mm*2mm), the zirconia restoration with pre-coated MPN (Fe-TA) coating as described in Example 4 (zirconia-MPN), and the zirconia restoration with MPN (Fe-TA) coating removed as described in Example 4 (zirconia-MPN-saliva-HCl-NaOH). The results are as follows: Figure 2 As shown in A to E.

[0081] Depend on Figure 2 As can be seen from A, after the MPN(Fe-TA) coating was successfully synthesized, the color of the zirconia ceramic block changed from white to purple; after the MPN(Fe-TA) coating was removed, the color of the zirconia ceramic block changed back from purple to white.

[0082] Depend on Figure 2 As shown in B to E, the zirconium oxide surface is pitted after sandblasting. After being coated with MPN (Fe-TA) coating, the surface becomes relatively flat. Under magnification, film deposition and MPN (Fe-TA) aggregates can be seen. After the MPN (Fe-TA) coating is removed, the surface returns to its pitted state.

[0083] 2. Fourier transform infrared (FT-IR) spectroscopy was performed on the sandblasted zirconia ceramic block (10mm*10mm*2mm), the zirconia restoration with pre-coated MPN (Fe-TA) layer as described in Example 4 (zirconia-MPN), and the zirconia restoration with MPN (Fe-TA) layer removed as described in Example 4 (zirconia-MPN-saliva-HCl-NaOH). The results are as follows: Figure 3 As shown.

[0084] Depend on Figure 3 It can be seen that the zirconia ceramic block coated with MPN (Fe-TA) was found to have an infrared signature at a wavelength of 2983.67 cm⁻¹. -1 The presence of a tannic acid phenolic hydroxyl absorption peak indicates that the MPN(Fe-TA) coating was successfully applied. This absorption peak disappeared after the coating was removed, similar to the cleaned zirconia ceramic block.

[0085] 3. X-ray photoelectron spectroscopy (XPS) was performed on the sandblasted zirconia ceramic block (10mm*10mm*2mm), the zirconia restoration with pre-coated MPN (Fe-TA) coating as described in Example 4 (zirconia-MPN), and the zirconia restoration with MPN (Fe-TA) coating removed as described in Example 4 (zirconia-MPN-saliva-HCl-NaOH). The results are as follows: Figure 4 As shown.

[0086] Depend on Figure 4 It can be seen that after the coating is applied, the C1s element on the surface increases (the coating contains TA), the Zr3d element decreases significantly (the coating covers the surface of the zirconia block), and the Fe2p element appears (the coating contains Fe). All of these indicate that the MPN (Fe-TA) coating was successfully applied. After the coating is removed, the surface element content is similar to that of the zirconia block, indicating that the coating has been successfully removed.

[0087] 4. Water contact angle hydrophilicity tests (WCA) were performed on the sandblasted zirconia ceramic block (10mm*10mm*2mm), the zirconia restoration with pre-coated MPN (Fe-TA) layer as described in Example 4 (zirconia-MPN), and the zirconia restoration with MPN (Fe-TA) layer removed as described in Example 4 (zirconia-MPN-saliva-HCl-NaOH). The results are as follows: Figure 5 As shown.

[0088] Depend on Figure 5 It can be seen that the average static water contact angle of the zirconia ceramic block surface after sandblasting is 47.94°, the average static water contact angle of the zirconia restoration with pre-coated MPN (Fe-TA) coating (zirconia-MPN) is 29.77°, and the average static water contact angle of the zirconia restoration with MPN (Fe-TA) coating removed (zirconia-MPN-saliva-HCl-NaOH) is 48.41°.

[0089] Experimental Example 2

[0090] 1. Fourier transform infrared (FT-IR) spectroscopy was performed on the following zirconia restorations: the zirconia restoration with MPN (Fe-TA) coating removed (zirconia-MPN-saliva-HCl-NaOH) described in Example 4; the zirconia restoration with MPN (Fe-TA) coating after saliva treatment described in Example 4 (zirconia-MPN-saliva); the zirconia restoration with MPN (Fe-TA) coating pre-coated in Example 4 (zirconia-MPN); the zirconia restoration after saliva treatment described in Comparative Example 2 (zirconia-saliva); and the sandblasted zirconia ceramic block (10mm*10mm*2mm) described in Comparative Example 1. The results are as follows: Figure 6 As shown.

[0091] Depend on Figure 6 It can be seen that the zirconia ceramic block contaminated with saliva was 1394.08 cm². -1 An absorption peak is visible at this point. Here, CN represents the abundant amide band in salivary proteins, which is used as the absorption peak of salivary proteins. However, after zirconium oxide is coated, immersed in saliva, and then removed by acid, no absorption peak was detected on the surface, indicating that there is no protein adsorption on the surface.

[0092] 2. The zirconia restoration with the MPN (Fe-TA) coating removed as described in Example 4 (zirconia-MPN-BSA-HCl-NaOH) and the sandblasted zirconia ceramic block (10mm*10mm*2mm) as described in Comparative Example 1 were subjected to bovine serum albumin immunofluorescence assay (BSA-FITC). The results are as follows: Figure 7 As shown.

[0093] Depend on Figure 7It can be seen that after zirconium oxide is immersed in calf serum protein for immunofluorescence labeling, the surface fluorescence signal is strong. However, after the protein is immersed in the MPN (Fe-TA) coated group and the coating is removed, almost no fluorescence signal is observed on the surface. This shows that the MPN (Fe-TA) coating can effectively isolate protein contamination.

[0094] Experimental Example 3

[0095] 1. The antibacterial function of the zirconia restorations in the coating group of Example 4 and the cleaning group of Comparative Example 1 was tested. The antibacterial rate of the coating was calculated by plate colony counting. *Streptococcus mutans*, a common oral bacteria, was selected as the model bacteria for the antibacterial test. It was cultured at 37°C under constant temperature anaerobic conditions (80% N2, 10% N2, and 10% CO2), revived, purified, and 1*10... 4 CFU / ml bacterial suspension was prepared for use. Zirconia specimens were irradiated with UV light on both sides for 40 min each before and after coating preparation (n=3). The specimens were placed in 24-well plates, and 100 μl of the bacterial suspension was added to the surface of each sample. The plates were then anaerobically incubated for 4 h. Subsequently, 1 ml of BHI liquid medium was added to each well, and anaerobic incubation continued for 24 h. The specimens were then removed and gently rinsed with sterile PBS buffer to remove suspended bacteria from the sample surface. The samples were then placed in sterile centrifuge tubes containing PBS, sonicated for 60 s, and then vortexed for 3 min to fully dissolve the bacteria from the sample surface into the PBS. This bacterial suspension was then diluted 100-fold, and 100 μl was transferred to sterile solid agar medium. The medium was evenly spread using a disposable sterile spreader and anaerobically incubated at 37°C for 24 h. The colony count on each medium was then performed.

[0096] Calculate the antibacterial rate of the coating using the following formula:

[0097] (AR): AR = (AB) / A * 100%, where A is the average colony count of clean zirconia, and B is the average colony count of the coated group. The results are as follows: Figure 8 As shown.

[0098] Zirconia restorations from the coating group of Example 4 and the cleaning group of Comparative Example 1 were co-cultured anaerobicly with Streptococcus mutans, followed by scanning electron microscopy observation. The results are as follows: Figure 9 As shown.

[0099] Depend on Figure 8It is known that the MPN(Fe-TA) coating has a significant antibacterial effect, with an antibacterial rate of up to 66.4%. This is because the tannic acid TA in the MPN(Fe-TA) coating contains abundant hydroxyl groups (metal ion chelating agents), which can reduce the activity of metalloenzymes, extract the metal ions needed by microorganisms, and inhibit bacterial growth; at the same time, the multi-functional phenolic groups of TA can disrupt the stability and integrity of cell membranes; most importantly, TA can reduce the activity of glucosyltransferase GTF (GTF can promote the adhesion of Streptococcus, the largest genus of bacteria in the oral cavity's natural flora, to the tooth surface), thereby inhibiting bacterial adhesion and achieving an antibacterial effect.

[0100] Depend on Figure 9 It can be seen that a large number of Streptococcus variants were observed in the clean group, while the number was relatively reduced in the pre-coated group. Under magnification, bacterial division and cell membrane deformation were visible on the surface of the coated group. This indicates that the coated group can achieve antibacterial effect by inhibiting bacterial adhesion and disrupting bacterial cell membrane stability.

[0101] 2. The bonding strength of the zirconia restorations in the coating group of Example 4, the cleaning group of Comparative Example 1, the saliva contamination group of Comparative Example 2, the alcohol wiping group of Comparative Example 3, and the Ivoclean group of Comparative Example 4 was tested. The specific method was as follows: Zirconia restoration bonding specimens (clinical resin bonding system) were prepared in vitro, and the long-term (1 year) aging of intraoral use was simulated by a hot and cold cycle instrument (the specimens were immersed in 55°C and 5°C for 10,000 cycles, each immersion for 20 seconds) and the immediate bonding strength, aging bonding strength and fracture strength of the above 5 groups of zirconia restorations were measured by a universal testing machine. The sample size n=10.

[0102] The immediate bond strength results of the above 5 groups of zirconia restorations are as follows: Figure 10 As shown, the aging bond strength results are as follows: Figure 11 As shown, the fracture mode results are as follows: Figure 12 As shown.

[0103] Depend on Figure 10 The results show that the average immediate bond strength of the saliva-contaminated group was 5.72 MPa, the average immediate bond strength of the alcohol-wiping group was 7.275 MPa, the average immediate bond strength of the Ivoclean group was 14.717 MPa, and the average immediate bond strength of the coating group was 14.772 MPa. This indicates that the cleaning effect of the coating group was basically the same as that of the Ivoclean group and the cleaning group.

[0104] Depend on Figure 11The results show that after aging, the average bond strength of the cleaning group was 11.19 MPa, the average bond strength of the saliva-contaminated group was 2.078 MPa, the average bond strength of the alcohol-wiped group was 3.4 MPa, the average bond strength of the Ivoclean group was 7.9789 MPa, and the average bond strength of the coating group was 10.802 MPa. This indicates that aging affects the bond strength of zirconia, with the chemical cleaning agent group showing poor durability and the coating group showing superior performance.

[0105] Depend on Figure 12 It can be seen that in the immediate bond fracture mode, the cleaning group, chemical cleaning group, and MPN (Fe-TA) coating group mainly exhibited mixed fracture, while the saliva contamination group and alcohol wiping group mainly exhibited bond fracture. After aging, all groups showed bond fracture as the main type of fracture (bonded fracture: fracture occurs between the resin adhesive and the ceramic interface; cohesive fracture: fracture occurs inside the resin adhesive, and the ceramic surface is covered by the resin adhesive; mixed fracture: both occur, with the ceramic surface partially covered by the resin adhesive). Under scanning electron microscopy, it was observed that the surface of the bond fractured ceramic had no resin adhesive, and under magnification, a pitted structure after sandblasting was visible. The surface of the mixed fracture showed residues of resin adhesive and primer, and some exhibited a pitted morphology of zirconia after sandblasting.

[0106] 3. The zirconia restorations in the coating group of Example 4, the cleaning group of Comparative Example 1, the saliva-contaminated group of Comparative Example 2, the alcohol-wiping group of Comparative Example 3, and the Ivoclean group of Comparative Example 4 were observed by scanning electron microscopy and analyzed by X-ray photoelectron spectroscopy (XPS). The results are as follows: Figures 13-14 As shown.

[0107] Depend on Figure 13 It can be seen that after sandblasting, the surface of zirconia is uneven. After saliva protein adsorption, a protein film can be seen covering the surface. After wiping with alcohol, there is no obvious change in the surface. After chemical cleaning with Ivoclean, the surface returns to a pitted morphology similar to the cleaned group, but small zirconia particles are visible as residues. The MPN (Fe-TA) coating group shows a pitted result on the surface, similar to the cleaned group. This indicates that the chemical cleaning Ivoclean group can effectively remove saliva contamination, and the coating group has the same effect.

[0108] Depend on Figure 14 It was found that the carbon content on the zirconia surface increased significantly after saliva contamination, and the nitrogen content also increased substantially. There was no significant change after wiping with alcohol. The carbon content on the surface of the Ivoclean chemical cleaner group decreased significantly, and nitrogen was almost undetectable, but the zirconium content was slightly higher than in the cleaned group. The elemental analysis results of the coating group were similar to those of the cleaned group. This indicates that the Ivoclean chemical cleaner can effectively remove saliva contamination from the surface of zirconia restorations, but it leaves small zirconia particles, while the coating group can isolate saliva contamination without leaving any residue.

Claims

1. A method for preparing a removable nano-coating that can isolate saliva contamination and improve the adhesive strength of zirconia restorations, characterized in that, The steps include the following: (1) Clean the substrate material; (2) Prepare a tannic acid solution with a concentration of 3~4 mg / mL and a ferric chloride hexahydrate solution with a concentration of 0.75~1 mg / mL; (3) Add ferric chloride hexahydrate solution and tannic acid solution to the cleaned substrate material in sequence. Vortex for 20-60s after each addition, adjust the pH value to 7-9, continue vortexing for 20-60s, clean and dry, and obtain a nano-removable coating that can isolate saliva contamination and improve the bonding strength of zirconia restoration. The volume ratio of the tannic acid solution to the ferric chloride hexahydrate solution is 1:1, and the mass concentration ratio is 4:

1.

2. The preparation method according to claim 1, characterized in that, In step (1), the substrate material is a zirconium oxide restoration.

3. The preparation method according to claim 1, characterized in that, In step (1), the cleaning method is as follows: add anhydrous ethanol to the substrate material, ultrasonically clean for 10 minutes, then replace with deionized water and continue ultrasonic cleaning for 5 minutes.

4. The preparation method according to claim 1, characterized in that, In step (2), the concentration of the tannic acid solution is 3.2 mg / mL.

5. The preparation method according to claim 1, characterized in that, In step (2), the concentration of the ferric chloride hexahydrate solution is 0.8 mg / mL.

6. A nano-removable coating that can isolate saliva contamination and improve the adhesive strength of zirconia restorations, characterized in that, It is prepared according to the preparation method described in any one of claims 1 to 5.

7. The application of the nano-removable coating of claim 6, which can isolate saliva contamination and improve the bonding strength of zirconia restorations, in the preparation of pre-coated MPN-coated restorations.

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