A self-cleaning coating material, a self-cleaning aligner and a method of making the same

Abstract

The application provides a self-cleaning coating material, a self-cleaning appliance and a preparation method thereof, and relates to the technical field of dental appliances, wherein the self-cleaning coating material is prepared by mixing poly-N-isopropyl acrylamide and acrylic acid-based oligomers in a mass ratio of 1:100-1:10 in anhydrous ethanol; the self-cleaning appliance is obtained by spraying the self-cleaning coating material on a polymer shell composed of 3D printing and a polyurethane matrix and then performing post-curing treatment; and other functional indicators are added according to actual requirements; the self-cleaning coating material can adjust its characteristics according to changes in oral temperature, effectively reacts in the process of bacterial biofilm formation, improves the cleaning efficiency and convenience of the appliance, and reduces the cleaning skill requirements for users.

Description

Technical Field

[0001] This invention relates to the field of dental appliance technology, and in particular to a self-cleaning coating material, a self-cleaning orthodontic appliance, and a method for preparing the same. Background Technology

[0002] In traditional orthodontic methods, especially with clear aligners, cleaning and maintenance are crucial issues. Because the aligners are in constant contact with teeth, food residue and bacteria easily accumulate. These substances mix with saliva, leading to the formation of stubborn plaque and biofilm on the aligner surface. This buildup not only affects the transparency and aesthetics of the aligners but can also cause oral hygiene problems such as halitosis and gingivitis.

[0003] Currently, common methods for cleaning orthodontic appliances include physical brushing (using a toothbrush) and chemical cleaning (using a cleaning solution). However, these methods often fail to completely remove stains from the appliances, especially those present in tiny cracks and fine structures. Physical brushing may damage the surface of the appliances, affecting their transparency and aesthetics; long-term use of chemical cleaners may corrode or discolor the materials. Furthermore, cleaning orthodontic appliances requires additional time and effort from the user, and improper cleaning can damage the appliances or leave them uncleaned, thus affecting the orthodontic outcome.

[0004] Conventional techniques and methods have certain limitations and characteristics in addressing this issue: First, the chosen orthodontic appliance material needs to possess appropriate strength and flexibility to accommodate tooth movement, which limits the cleaning methods and types of chemicals that can be used. Second, the design of orthodontic appliances usually needs to be individualized to accommodate different patient needs, making the cleaning process difficult, especially at the microscopic level. Finally, the effectiveness of cleaning orthodontic appliances largely depends on the user's cleaning habits and methods; improper operation may damage the appliances or result in incomplete cleaning.

[0005] To address the shortcomings of existing orthodontic appliances in cleaning, this invention discloses a self-cleaning coating material, a self-cleaning orthodontic appliance, and a method for preparing the same. These methods solve the inherent defects of traditional orthodontic appliances in terms of cleaning and maintenance. The invention employs an orthodontic appliance material with appropriate strength and flexibility to adapt to tooth movement, utilizes 3D printing technology to meet the personalized needs of different patients, and uses a self-cleaning coating material to improve the cleaning efficiency and convenience of the orthodontic appliance, reducing the cleaning skills required of the user. Summary of the Invention

[0006] In view of this, embodiments of this application provide a self-cleaning coating material, a self-cleaning orthodontic appliance, and a method for preparing the same, to improve the cleaning efficiency of the orthodontic appliance and reduce the cleaning skill requirements for the user. Embodiments of this application provide the following technical solutions:

[0007] On one hand, embodiments of this application provide a self-cleaning coating material comprising poly(N-isopropylacrylamide) and acrylic oligomer mixed in a mass ratio of 1:100 to 1:10, wherein anhydrous ethanol is used as a solvent.

[0008] Furthermore, the acrylic oligomer includes polyacrylic acid and / or sodium polyacrylate.

[0009] Furthermore, at 25°C, the viscosity of the self-cleaning coating material is 20–30 mPa·s; at 30–35°C, the self-cleaning coating material exhibits a transition from hydrophilic to hydrophobic.

[0010] Furthermore, the self-cleaning coating material also includes a functional indicator.

[0011] Furthermore, the functional indicator is a pH-sensitive dye or a pH-sensitive polymer, wherein the pH-sensitive dye includes bromothymol blue, phenol red, methyl orange, and methyl red, and the pH-sensitive polymer includes poly(4-vinylpyridine), polyethyleneimine, and polyurethane.

[0012] On the other hand, embodiments of this application provide a self-cleaning orthodontic appliance, comprising: a polymer housing having an arrangement of cavities configured to receive one or more teeth; a coating located on at least a portion of the polymer housing, the polymer housing being a polyurethane matrix, a (meth)acrylate monomer having one or more single functional groups, and further comprising a diluent and a photoinitiator; the coating comprising a self-cleaning coating material of any of the above.

[0013] Furthermore, the acrylate monomer is one of methyl methacrylate, 1,6-hexanediol diacrylate, or trimethylolpropane triacrylate.

[0014] On the other hand, this application provides a method for preparing a self-cleaning orthodontic appliance, characterized by comprising the following steps:

[0015] S1. Use 3D printing technology to print the polymer shell;

[0016] S2. Pre-treat the polymer shell to prepare a self-cleaning coating material;

[0017] S2.1. Heat the incompletely photocured resin on the surface of the polymer shell to 26-28°C;

[0018] S2.2. Mix poly(N-isopropylacrylamide) and acrylic oligomer at a mass ratio of 1:100 to 1:10;

[0019] S2.3. Using anhydrous ethanol as a solvent, stir continuously until the poly(N-isopropylacrylamide) and acrylic oligomer are completely dissolved to form a copolymer solution;

[0020] S3. The self-cleaning coating material is evenly sprayed onto the polymer shell;

[0021] S4. The self-cleaning coating material is post-cured by irradiating it with UV light.

[0022] Furthermore, the polymer shell described in S3 also includes a functional indicator.

[0023] Furthermore, the functional indicator is a pH-sensitive dye or a pH-sensitive polymer.

[0024] Compared with the prior art, the beneficial effects that the at least one technical solution adopted in the embodiments of this application can achieve include at least:

[0025] 1. The self-cleaning coating material in this invention adjusts its properties according to changes in oral temperature, enabling the coating to react effectively during the formation of bacterial biofilm, helping to remove dirt and microorganisms already attached to the surface, and improving the cleaning efficiency and convenience of the orthodontic appliance.

[0026] 2. The self-cleaning coating material in this invention has excellent sustainability and durability. Its temperature-sensitive properties are retained even after long-term use, which helps maintain its long-term cleaning effect.

[0027] 3. The self-cleaning orthodontic appliance in this invention uses an orthodontic appliance material with appropriate strength and flexibility to adapt to tooth movement, uses 3D printing technology to adapt to the personalized needs of different patients, and uses a self-cleaning coating material to improve the cleaning efficiency and convenience of the orthodontic appliance, reducing the cleaning skill requirements of the user.

[0028] 4. In one embodiment of the self-cleaning coating material of the present invention, pH-sensitive dyes and pH-sensitive polymers are added to prepare a self-cleaning coating that can effectively indicate the degree of dirt accumulation in the orthodontic appliance. The color change of the coating using pH-sensitive dyes and the volume change and degree of dissolution of the coating using pH-sensitive polymers provide users with intuitive cleaning reminders, which helps to improve oral hygiene and the maintenance of the orthodontic appliance. Attached Figure Description

[0029] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 This is a comparison diagram of the anti-fouling effect of a self-cleaning coating material of the present invention;

[0031] Figure 2 This is a comparison chart of the anti-fouling effect of a self-cleaning coating material of the present invention as a function of temperature.

[0032] Figure 3 This is a process diagram of the preparation method of a self-cleaning orthodontic appliance according to the present invention. Detailed Implementation

[0033] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0034] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that, in the absence of conflict, the following embodiments and features in the embodiments can be combined with each other. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0035] The technical principle of this invention is based on the temperature-sensitive properties of poly(N-isopropylacrylamide) (PNIPAAm): PNIPAm is a polymer with unique phase transition properties. When the ambient temperature is below its low critical solution temperature (LCST, between 30-35°C), PNIPAm is hydrophilic; while when the temperature exceeds the LCST, PNIPAm becomes hydrophobic.

[0036] Hydrophilicity and hydrophobicity are properties that describe the behavior or affinity of a substance in water. Generally, substances with strong hydrophilicity are more likely to disperse or dissolve in water, while substances with strong hydrophobicity tend to repel water molecules and aggregate. For temperature-sensitive materials, their hydrophilicity and hydrophobicity can be switched rapidly and reversibly by adjusting the temperature.

[0037] PNIPAAm is routinely used in the fabrication of temperature-responsive drug delivery systems (which are particularly valuable in cancer therapy and targeted drug delivery) and can also be used in cell culture and tissue engineering (such as 3D cell culture scaffolds), but we have found that this property can be used to create an orthodontic coating that can automatically clean itself at a certain temperature.

[0038] The specific method for obtaining color change data in the experimental examples in this invention is as follows:

[0039] S1. Image Acquisition: Acquire images of the orthodontic appliance in a photography box with a gray background, ensuring consistency between lighting and background, using standardized photography equipment, and fixing exposure, ISO, and white balance settings;

[0040] S2. Color Correction: Color correction is performed using a gray background to ensure image color accuracy and consistency. Standardized color correction is performed using professional image processing software (such as Adobe Photoshop).

[0041] S3. Color Extraction and Analysis: Extract color from the center of the incisor crown of each orthodontic appliance to ensure consistency of the extraction area. Use the color sampling tool of image processing software to accurately extract color information.

[0042] S4. Color Change Quantification: The extracted color data is converted into HSV values, and the initial and final color values ​​are recorded. The CIE ΔE 2000 formula is applied to calculate the ΔE value of the color change, which serves as a quantitative indicator of color change. The anti-fouling performance of the product is evaluated based on the ΔE value. A smaller ΔE value indicates less color change and stronger anti-fouling performance.

[0043] The basic form of the formula in S4 is:

[0044]

[0045] Each symbol represents a different aspect of color difference, including brightness (L), chromaticity (C), and hue (H). k L k C k H It is a weighted function, S L S C S H It is a scaling function, R T It is a rotation function used for non-linear adjustment of hue.

[0046] On one hand, embodiments of this application provide a self-cleaning coating material comprising poly(N-isopropylacrylamide) and acrylic oligomer mixed in a mass ratio of 1:100 to 1:10, wherein anhydrous ethanol is used as a solvent.

[0047] Furthermore, acrylic oligomers include polyacrylic acid and / or sodium polyacrylate. It should be understood that acrylic oligomers are a class of organic compounds containing acrylic acid. Acrylic oligomer compounds having one or more acrylic functional groups and exhibiting good biocompatibility and suitable adhesion can be used to prepare the self-cleaning coating in one embodiment.

[0048] Experimental Example 1:

[0049] Experimental Overview: This Experiment Example 1 aims to evaluate the anti-fouling performance of a self-cleaning coating material according to the embodiments of this application, specifically comparing its cleaning performance with that of uncoated orthodontic appliances and orthodontic appliances with hydrophobic coatings (mainly composed of polytetrafluoroethylene) under different types of contaminants.

[0050] Experimental steps: 1. Immerse the three types of orthodontic appliances in sealed containers containing different contaminants. The contaminants are various foods and beverages that represent common sources of pollution in daily life, specifically orange juice, black tea, red wine, soy sauce, coffee, curry, cola, and pumpkin soup.

[0051] 2. Place the sealed container in a water bath at 30-37℃ for one week to simulate the oral cavity environment;

[0052] 3. After removing the three types of orthodontic appliances from the sealed container, immerse them in clean water at 50°C for 2 hours to observe the cleanliness of the dirt.

[0053] 4. Capture images of the dirt's cleaning status, record and calculate the color change ΔE value.

[0054] Figure 1 This is a comparison chart of the anti-fouling effect of the self-cleaning coating material of this invention. The diagonal lines represent orthodontic appliances without coating, the horizontal lines represent orthodontic appliances with hydrophobic coatings, and the dot matrix represents orthodontic appliances with the self-cleaning coating of this invention. The horizontal axis represents the three types of orthodontic appliances under different contaminants, and the vertical axis represents the final contamination ΔE value of the three types of orthodontic appliances after immersion in a 50°C water bath for 2 hours. By recording the color change ΔE values ​​of the three types of orthodontic appliances under different contaminants, it is clear that:

[0055] Uncoated orthodontic appliances perform the worst in terms of cleanliness and hydrophobicity because they do not have any additional protective layer to prevent the accumulation of surface dirt.

[0056] Hydrophobic coated orthodontic appliances (PTFE) perform moderately in terms of cleanliness and hydrophobicity. They have strong hydrophobicity, which mainly provides the ability to repel water and water-soluble substances. They can effectively prevent the adsorption of moisture and other liquids, thereby keeping the surface of the orthodontic appliance clean. However, the hydrophobic coating has poor interaction with other aqueous solutions containing pigment deposits and / or corrosion, and its effect on removing dirt and microorganisms that have already adhered to the surface is limited.

[0057] The poly-N-isopropylacrylamide coating of this application exhibits the best performance in terms of cleanliness and hydrophobicity. It can change from hydrophobic to hydrophilic at a certain temperature (LCST), and has a good effect on removing dirt and microorganisms that have already adhered to the surface, providing a good cleaning effect.

[0058] Comparing orthodontic appliances with no coating, hydrophobic coating (mainly composed of polytetrafluoroethylene), and PNIPAAm coating, the experimental results show that after immersion in a 50°C water bath for 2 hours, the orthodontic appliance with PNIPAAm coating exhibits a significant advantage in stain resistance.

[0059] In some embodiments, the viscosity of the self-cleaning coating material is 20–30 mPa·s at 25°C to ensure the uniformity of the coating process and the coating quality; at 30–35°C, the self-cleaning coating material exhibits a hydrophilic to hydrophobic transition. The physicochemical properties testing procedure for the self-cleaning coating material solution is as follows:

[0060] a. Viscosity test: The viscosity of the solution is measured using a rotational viscometer.

[0061] b. Temperature response test: Test the changes in hydrophilicity and hydrophobicity of the solution at different temperatures (20℃ to 40℃). Near the LCST of PNIPAAm (approximately 32℃), the solution should exhibit a significant hydrophilic-to-hydrophobic transition.

[0062] c. Stability testing: Long-term stability testing of the solution is conducted to check its property changes under different storage conditions, ensuring consistent performance in practical applications.

[0063] Experimental Example 2:

[0064] Experimental Overview: This Experimental Example 2 aims to evaluate the antifouling performance of a self-cleaning coating material according to the embodiments of this application, specifically by comparing the antifouling effects of the self-cleaning coating and the hydrophobic coating as temperature changes.

[0065] Experimental steps: 1. Immerse the two types of orthodontic appliances, one with a self-cleaning coating and the other with a hydrophobic coating, in a sealed container containing orange juice;

[0066] 2. Place the sealed container in a water bath at 30-37℃ for one week to simulate the oral cavity environment;

[0067] 3. After removing the two types of orthodontic appliances from the sealed container, immerse them in water baths at different temperatures of 35-60℃ for 2 hours;

[0068] 4. Collect images of the dirt cleaning status, record and calculate the final dirt ΔE value.

[0069] Figure 2 This is a comparison chart showing the anti-fouling effect of a self-cleaning coating material of the present invention as a function of temperature. The dashed line represents the self-cleaning coating, and the solid line represents the hydrophobic coating (based on polytetrafluoroethylene (PTFE) or silane compounds). The horizontal axis represents the water bath temperature of the two types of orthodontic appliances, and the vertical axis represents the final staining ΔE value of the two types of orthodontic appliances after 2 hours of immersion in the water bath. Figure 2As the temperature rises, the ΔE value of the self-cleaning coating of this invention decreases, demonstrating a good cleaning effect for removing orange juice contamination. The anti-fouling performance of the PNIPAAm coating increases with temperature, and at 45°C, the self-cleaning coating outperforms the hydrophobic coating. Poly(N-isopropylacrylamide) (PNIPAAm) coating is a temperature-sensitive polymer. At low temperatures, this coating is hydrophilic, which may be detrimental to removing contaminants such as orange juice. However, when the temperature exceeds its hydrophilic-hydrophobic transition point, the coating becomes hydrophobic, making it difficult for contaminants to adhere and facilitating contamination removal. In contrast, conventionally used hydrophobic coatings, such as those based on polytetrafluoroethylene (PTFE) or silane compounds, have hydrophobic properties primarily determined by their chemical composition and surface microstructure, and are relatively less affected by temperature. They typically lack environmental responsiveness, meaning they cannot adjust their properties according to changes in external conditions (such as temperature), and therefore cannot effectively react during bacterial biofilm formation.

[0070] In addition, hydrophobic coatings also have sustainability and durability issues compared to self-cleaning coatings: after long-term use or after physical damage, the hydrophobic properties of hydrophobic coatings may decrease, affecting their long-term cleaning effect.

[0071] In some embodiments, the self-cleaning coating material further includes a functional indicator for providing visual feedback on the oral environment. Further, the functional indicator is a pH-sensitive dye or a pH-sensitive polymer; the pH-sensitive dye includes bromothymol blue, phenol red, methyl orange, and methyl red; and the pH-sensitive polymer includes poly(4-vinylpyridine), polyethyleneimine, and polyurethane.

[0072] pH-sensitive dyes typically need to be combined with a polymer matrix before being used in coatings. Available pH-sensitive dyes include: 1. Bromothymol Blue: can be physically mixed or chemically grafted into the polymer matrix; 2. Phenol Red: can be covalently grafted onto polymer chains or encapsulated within the polymer matrix; 3. Methyl Orange: can be adsorbed onto the surface of polyelectrolyte polymers through charge interactions; 4. Methyl Red: can be introduced into polymers through blending or copolymerization. Specifically, some examples of combinations are as follows:

[0073] 1. Doping polyacrylamide (PAM) with bromophenol blue: Polyacrylamide itself is a nonionic polymer. By doping it with pH-sensitive dyes such as bromophenol blue, which change from colorless to colored under acidic conditions, the polymer can develop color in acidic environments. Under neutral and weakly alkaline environments, the dye reverts to its colorless state.

[0074] 2. pH-Sensitive Polymer Brushes: pH-sensitive dyes are grafted onto polymer chains to form "polymer brushes." These polymer brushes exhibit different conformational changes under different pH conditions, thus causing color changes. For example, a poly(methacrylate) polymer brush grafted with methyl red develops color in an acidic environment. Methyl red is mixed with PNIPAAM at a mass ratio of 0.5%, keeping the original ratio of PNIPAAM to oligomers unchanged, and other process parameters and methods also remain the same.

[0075] In addition, some pH-sensitive polymers are water-soluble, meaning they dissolve in acidic environments but are not easily dissolved in neutral or weakly alkaline environments. Observing for volume changes or dissolution can also serve as an indicator. Available pH-sensitive polymers include:

[0076] 1. Poly(4-vinylpyridine): In acidic environments, the nitrogen atom on the pyridine ring is protonated, forming a positive charge, which increases the water solubility. However, in neutral or alkaline environments, the nitrogen atom on the pyridine ring is not protonated, which reduces the hydrophilicity and thus decreases the solubility.

[0077] 2. Polyethyleneimine (PEI): PEI contains a large number of amino groups. These amino groups are easily protonated in acidic environments, which makes the polymer chains positively charged and enhances water solubility. In neutral or alkaline environments, the degree of protonation of the amino groups decreases, which weakens the solubility of the polymer.

[0078] 3. Polyurethane (PU) modified materials: Some specially modified polyurethanes may contain functional groups that can increase solubility under acidic conditions. For example, by introducing functional groups that are easily protonated (such as carboxyl groups), the material can be made more soluble in acidic environments.

[0079] Plaque buildup in the mouth can easily lead to the formation of acidic substances, which can erode teeth. By combining pH-sensitive dyes or polymers with PNIPAAm, a coating can be prepared that effectively indicates the degree of plaque accumulation on the orthodontic appliance. Changes in coating color, volume, and dissolution provide users with intuitive cleaning reminders, helping to improve oral hygiene and appliance maintenance. This technology offers an innovative self-monitoring function for orthodontic appliance design.

[0080] Experimental Example 3:

[0081] Experimental Overview: This Experiment Example 1 aims to evaluate the pH indication performance of a self-cleaning coating material according to the embodiments of this application, specifically by comparing the same colorless liquid at different pH values.

[0082] Simulating pH changes in the oral cavity environment, the pH range was set from 4.0 to 7.5. It was found that self-cleaning aligners with this pH-sensitive dye appeared red in liquids below pH 4.4, turned yellow in liquids above pH 6.2, and faded to colorless in neutral and alkaline environments. Within the pH range of 5.5 to 6.5, the color change ΔE value exceeded 0.5, meaning the color change was sufficiently noticeable to the naked eye.

[0083] On the other hand, embodiments of this application provide a self-cleaning orthodontic appliance, comprising: a polymer housing having an arrangement of cavities configured to receive one or more teeth; a coating located on at least a portion of the polymer housing, the polymer housing being a polyurethane matrix, a (meth)acrylate monomer having one or more single functional groups, and further comprising a diluent and a photoinitiator; the coating comprising a self-cleaning coating material comprising any one of the above.

[0084] The polyurethane matrix (PUA) uses prepolymerized polyurethane, accounting for 20% to 50% of the total formulation by weight. PUA with appropriate molecular weight, good biocompatibility, and suitable mechanical strength is selected. The acrylate monomers are one of methyl methacrylate, 1,6-hexanediol diacrylate, or trimethylolpropane triacrylate. 5% ethyl acetate is added as a diluent to adjust the viscosity of the substrate and ensure good printing flow. 2-hydroxy-2-methylpropionate (HMPP) is used as a photoinitiator, accounting for 5% of the total formulation, to ensure effective photocuring.

[0085] In some embodiments, other additives are also included: UV blockers, inhibitors, and antioxidants, etc., to improve its performance and durability.

[0086] Figure 3 This is a process diagram of a method for preparing a self-cleaning orthodontic appliance according to the present invention, including the following steps:

[0087] S1. Print the polymer shell using 3D printing technology; the 3D printing parameters are: illumination time set to 10-15 seconds per layer, and illumination intensity adjusted to 1-5 mW / cm². 2 This process solidifies the PUA, but leaves resin containing photoinitiators on the surface. Printing process: A DLP 3D printer is used for printing, and the support height is raised after each layer is printed to form the next layer.

[0088] S2. Pretreatment of the polymer shell to prepare a self-cleaning coating material:

[0089] S2.1. Heat the partially cured resin on the surface of the polymer shell to 26-28°C; before spraying, heat the partially cured resin on the surface of the orthodontic appliance to 27°C, controlling ±1°C, to improve the miscibility of PNIPAAm solution and resin.

[0090] S2.2. Mix poly(N-isopropylacrylamide) and acrylic oligomer at a mass ratio of 1:100 to 1:10; the mixing ratio of PNIPAAM to oligomer should not be less than 1:100, otherwise it will be difficult to achieve temperature sensitivity.

[0091] S2.3. Using anhydrous ethanol as a solvent, stir continuously until poly(N-isopropylacrylamide) and acrylic oligomers are completely dissolved to form a copolymer solution; stir continuously with a magnetic stirrer for 4 hours at room temperature to ensure uniform dispersion of PNIPAAM and oligomers in the solution;

[0092] S3. Apply the self-cleaning coating material evenly to the polymer housing; for coating mixture application: use a fine nozzle with a nozzle diameter of 50-100 micrometers to achieve a fine and uniform coating effect; set the spraying pressure to 2-3 bar and maintain the distance between the nozzle and the orthodontic appliance surface at 15-20 cm to achieve the best spraying effect; control the spraying speed to ensure the uniformity of the coating, with a moving speed of approximately 10-15 cm per second.

[0093] S4. Post-curing treatment of the self-cleaning coating material by irradiation with UV light; service strength is 300-400 mW / cm². 2 A UV light source is used to ensure full cross-linking of the coating and resin; the total irradiation time is controlled at 10-15 minutes to fully cure the coating and resin; an intermittent irradiation method is used, with a 30-second pause after each 2-minute irradiation to reduce heat buildup and protect the structural integrity of the orthodontic appliance.

[0094] In some embodiments, the self-cleaning orthodontic appliance of the present invention further includes a functional indicator, which may be a single-layer structure bonded to poly-N-isopropylacrylamide or a multi-layer coating structure composed of the self-cleaning coating of the present invention. The functional indicator is a pH-sensitive dye or pH-sensitive polymer, providing intuitive cleaning reminders and helping to improve oral hygiene and appliance maintenance.

[0095] Furthermore, the coating in a self-cleaning orthodontic appliance may also include one or more combinations of antibacterial coatings, whitening coatings, and / or anti-caries coatings.

[0096] In this specification, the same or similar parts between the various embodiments can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. In particular, the descriptions of the embodiments described later are relatively simple, and relevant parts can be referred to the descriptions of the foregoing embodiments.

[0097] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A self-cleaning coating material for self-cleaning orthodontic appliances, characterized in that, It includes poly-N-isopropylacrylamide and acrylic oligomers mixed in a mass ratio of 1:100 to 1:10, wherein anhydrous ethanol is used as a solvent; The acrylic oligomers include polyacrylic acid and / or sodium polyacrylate; At 25°C, the viscosity of the self-cleaning coating material is 20~30 mPa·s; at 30~35°C, the self-cleaning coating material exhibits a hydrophilic to hydrophobic transition. The self-cleaning coating material also includes a functional indicator; the functional indicator is a pH-sensitive dye or a pH-sensitive polymer, wherein the pH-sensitive dye is selected from bromothymol blue, phenol red, methyl orange and methyl red, and the pH-sensitive polymer is selected from poly(4-vinylpyridine), polyethyleneimine and polyurethane.

2. A self-cleaning orthodontic appliance, comprising: A polymer shell having an arrangement of cavities configured to receive one or more teeth; A coating located on at least a portion of a polymer housing, characterized in that the polymer housing is a polyurethane matrix, a (meth)acrylate monomer having one or more monofunctional groups, and further comprising a diluent and a photoinitiator; the coating comprises the self-cleaning coating material of claim 1.

3. The self-cleaning orthodontic appliance according to claim 2, characterized in that, The acrylate monomer is one of methyl methacrylate, 1,6-hexanediol diacrylate, or trimethylolpropane triacrylate.

4. A method for preparing a self-cleaning orthodontic appliance, characterized in that, Includes the following steps: S1. Use 3D printing technology to print the polymer shell; S2. Pre-treat the polymer shell to prepare a self-cleaning coating material; at 25°C, the viscosity of the self-cleaning coating material is 20~30 mPa·s; at 30~35°C, the self-cleaning coating material exhibits a hydrophilic to hydrophobic transition; S2.

1. Heat the incompletely photocured resin on the surface of the polymer shell to 26~28°C; S2.

2. Mix poly(N-isopropylacrylamide) and acrylic oligomer at a mass ratio of 1:100 to 1:10; S2.

3. Using anhydrous ethanol as a solvent, continuously stir until the poly-N-isopropylacrylamide and acrylic oligomer are completely dissolved to form a copolymer solution, which is the self-cleaning coating material; S3. The self-cleaning coating material is uniformly sprayed onto the polymer shell; the polymer shell also includes a functional indicator, which is a pH-sensitive dye or a pH-sensitive polymer; S4. The self-cleaning coating material is post-cured by irradiating it with UV light.

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