4D printing aligner material based on shape memory polymer and preparation method and application thereof, and 4D printing aligner

Abstract

The application provides a 4D printing invisible appliance material based on a shape memory polymer and a preparation method and application thereof, and a 4D printing invisible appliance, and belongs to the technical field of high polymer materials. The 4D printing invisible appliance material is prepared from raw materials including the following components in mass fractions: polyester polyol 100-500 parts, isocyanate 400-800 parts, chain extender 400-800 parts, 1-vinyl-2-pyrrolidone 200-4800 parts, photoinitiator 5-35 parts, and polymerization inhibitor 1-15 parts. The 4D printing invisible appliance material is an invisible appliance material with shape memory performance. The crosslinking structure and hydrogen bond network structure of polyurethane endow the material with excellent shape memory performance. The material can have shape memory response within the oral temperature range, and finally apply slow and long-lasting light force to teeth through shape recovery force, so that the treatment efficiency is greatly improved.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, and in particular to a 4D-printed invisible orthodontic material based on shape memory polymer, its preparation method and application, and a 4D-printed invisible orthodontic device. Background Technology

[0002] Currently, the domestic and international orthodontic market is experiencing rapid growth. With the rapid advancements in biomaterials, computer-aided design, and manufacturing technologies, invisible orthodontic technology has attracted a large number of patients, especially adults, due to its aesthetics and comfort. However, existing invisible aligner materials suffer from severe stress relaxation, leading to problems such as excessive initial force on teeth, low tooth movement efficiency, and a large number of aligners required throughout the treatment, seriously affecting treatment outcomes and patient experience. Furthermore, the current manufacturing process for invisible aligners is complex, and the vacuum hot-pressing secondary molding process often results in insufficient precision in the aligners.

[0003] In recent years, shape memory polymers (SMPs), as a class of smart materials among cross-linked polymers, can autonomously recover from a temporary shape to its original shape after being subjected to specific stimuli (such as temperature changes). At the same time, due to their strong structural designability, excellent mechanical properties and adjustable shape memory transition temperature, they have gradually attracted widespread attention in the medical field.

[0004] In recent years, many scholars have attempted to use 4D printing technology to fabricate invisible aligners. By precisely curing photosensitive resin through digital light projection, the resulting aligners exhibit higher precision and accuracy. Furthermore, this effectively reduces costs and material waste. However, the related shape memory polymers do not exhibit shape memory effects at oral temperatures, resulting in low orthodontic efficiency. Summary of the Invention

[0005] In view of this, the purpose of this invention is to provide a 4D-printed invisible aligner material based on shape memory polymer, its preparation method and application, and a 4D-printed invisible aligner. The 4D-printed invisible aligner material provided by this invention can exhibit shape memory response within the oral temperature range, ultimately applying a slow-release and durable light force to the teeth through shape restoration force, thereby significantly improving orthodontic efficiency.

[0006] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0007] This invention provides a 4D-printed invisible orthodontic material based on shape memory polymer, which is made from the following raw materials in parts by weight: 100-500 parts of polyester polyol, 400-800 parts of isocyanate, 400-800 parts of chain extender, 200-4800 parts of 1-vinyl-2-pyrrolidone (NVP), 5-35 parts of photoinitiator, and 1-15 parts of polymerization inhibitor.

[0008] Preferably, the polyester polyol comprises polyethylene terephthalate-1,4-cyclohexanediol and / or polycarbonate diol.

[0009] Preferably, the number average molecular weight of the polycarbonate diol is 1000 to 2000.

[0010] Preferably, the chain extender comprises hydroxyethyl methacrylate and / or dimethylaminoethyl methacrylate.

[0011] This invention also provides a method for preparing the 4D-printed invisible orthodontic appliance material based on shape memory polymer described in the above technical solution, comprising the following steps:

[0012] Polyester polyol, isocyanate and chain extender are mixed and subjected to a prepolymerization reaction to obtain polyurethane prepolymer (PU);

[0013] The polyurethane prepolymer, 1-vinyl-2-pyrrolidone, photoinitiator and polymerization inhibitor are mixed to obtain the 4D printed invisible orthodontic material based on shape memory polymer.

[0014] Preferably, the mass ratio of the polyurethane prepolymer to 1-vinyl-2-pyrrolidone is 1-3:3-1.

[0015] Preferably, the temperature of the prepolymerization reaction is 60–80°C and the time is 2–3 hours.

[0016] The present invention also provides the application of the shape memory polymer-based 4D printed invisible aligner material described in the above technical solution or the shape memory polymer-based 4D printed invisible aligner material prepared by the preparation method described in the above technical solution in the preparation of oral invisible aligners.

[0017] The present invention also provides a 4D printed invisible orthodontic appliance, which is obtained by 4D printing from the 4D printed invisible orthodontic appliance material based on shape memory polymer as described in the above technical solution or the 4D printed invisible orthodontic appliance material based on shape memory polymer prepared by the preparation method described in the above technical solution.

[0018] Preferably, the parameters for 4D printing include: ultraviolet light wavelength of 350-400nm, irradiation time of 10-30s / layer, and printing temperature of 20-60℃.

[0019] This invention provides a 4D-printed invisible orthodontic material based on shape memory polymer, which is made from the following raw materials in parts by weight: 100-500 parts of polyester polyol, 400-800 parts of isocyanate, 400-800 parts of chain extender, 200-4800 parts of 1-vinyl-2-pyrrolidone, 5-35 parts of photoinitiator, and 1-15 parts of polymerization inhibitor.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0021] The 4D-printed invisible aligner material provided by this invention is an invisible aligner material with shape memory properties. Compared with existing invisible aligner materials, this invention utilizes the cross-linked structure and hydrogen bond network structure of polyurethane obtained by prepolymerization reaction of polyester polyol, isocyanate and chain extender to endow the material with excellent shape memory properties. It can undergo shape memory response within the oral temperature range, and finally achieve the application of slow-release and lasting light force to the teeth through shape restoration force. It can design high-precision, personalized invisible aligners that can continuously release light force in the mouth, thereby greatly improving orthodontic efficiency and reducing the number of aligners used.

[0022] This invention also provides a method for preparing the 4D printed invisible aligner material described in the above technical solution. Compared with the existing secondary molding vacuum hot pressing process for invisible aligner materials, the 4D printed invisible aligner material of this invention has a simple preparation method and can be applied to 4D printing to achieve high-precision, personalized invisible aligner printing and manufacturing.

[0023] Data from the embodiments show that the glass transition temperature of the material prepared by the present invention is -20 to 110°C, the yield stress is >30 MPa, the yield strain is >4%, the elastic modulus is >1500 MPa, and the shape recovery rate within 4 days at 37°C is >80%. Attached Figure Description

[0024] Figure 1 DMA test curves of the materials obtained in Examples 1-6 of this invention;

[0025] Figure 2 This is a bar chart showing the glass transition temperatures of the materials obtained in Examples 1-6 of the present invention.

[0026] Figure 3 These are shape memory demonstration diagrams of the materials obtained in Examples 1-6 of this invention;

[0027] Figure 4 These are stress-strain curves of the materials obtained in Examples 1 to 6 of this invention;

[0028] Figure 5 The image shows the 4D printing effect of the 4D printed invisible orthodontic appliance material in Example 5.

[0029] Figure 6 The DSC curve is for comparison. Detailed Implementation

[0030] This invention provides a 4D-printed invisible orthodontic material based on shape memory polymer, which is made from the following raw materials in parts by weight: 100-500 parts of polyester polyol, 400-800 parts of isocyanate, 400-800 parts of chain extender, 200-4800 parts of 1-vinyl-2-pyrrolidone, 5-35 parts of photoinitiator, and 1-15 parts of polymerization inhibitor.

[0031] Unless otherwise specified, all raw materials used in this invention are commercially available products in the field.

[0032] The preferred mass fraction of polyester polyol in the raw material of the 4D printed invisible orthodontic device provided by the present invention is 100, 200, 300, 400 or 500 parts.

[0033] In this invention, the polyester polyol preferably includes polyethylene terephthalate-1,4-cyclohexanediol and / or polycarbonate diol (PCDL).

[0034] In this invention, the number-average molecular weight of the polycarbonate diol is preferably 1000 to 2000.

[0035] Based on the mass of the polyester polyol, the preferred mass fraction of isocyanate in the raw material is 400, 500, 600, 700 or 800 parts.

[0036] In this invention, the isocyanate is preferably hexamethylene diisocyanate (HDI).

[0037] Based on the mass of the polyester polyol, the preferred mass fraction of the chain extender in the raw material is 400, 500, 600, 700 or 800 parts.

[0038] In this invention, the chain extender preferably includes hydroxyethyl methacrylate (HEMA) and / or dimethylaminoethyl methacrylate.

[0039] Based on the mass of the polyester polyol, the preferred mass fraction of 1-vinyl-2-pyrrolidone in the raw material is 200, 400, 500, 1000, 2000, 3000, 4000, 4500, or 4800 parts; the 1-vinyl-2-pyrrolidone, as a copolymer solvent, is a solvent for polyurethane prepolymers, photoinitiators, and polymerization inhibitors.

[0040] Based on the mass of the polyester polyol, the preferred mass fraction of the photoinitiator in the raw material is 5.5, 10, 15, 20, 25 or 34.5 parts.

[0041] In this invention, the photoinitiator preferably includes one or more of 2,2-dimethoxy-2-phenylacetophenone (DMPA), phenyl bis(2,4,6-trimethylbenzoyl)phosphine oxide (PPO), and 2,4,6-trimethylbenzoyl-diphenylphosphine oxide (TPO).

[0042] Based on the mass of the polyester polyol, the preferred mass fraction of the polymerization inhibitor in the raw material is 1, 1.65, 3, 5, 8, 10.35, or 15 parts.

[0043] In this invention, the polymerization inhibitor is preferably hydroquinone (also known as hydroquinone).

[0044] This invention also provides a method for preparing the 4D-printed invisible orthodontic appliance material based on shape memory polymer described in the above technical solution, comprising the following steps:

[0045] Polyester polyol, isocyanate and chain extender are mixed and subjected to a prepolymerization reaction to obtain polyurethane prepolymer;

[0046] The polyurethane prepolymer, 1-vinyl-2-pyrrolidone, photoinitiator and polymerization inhibitor are mixed to obtain the 4D printed invisible orthodontic material based on shape memory polymer.

[0047] This invention involves mixing polyester polyol, isocyanate, and chain extender to conduct a prepolymerization reaction, thereby obtaining a polyurethane prepolymer.

[0048] In this invention, the temperature of the prepolymerization reaction is preferably 60-80°C, specifically 60, 65, 70, 75 or 80°C, and the time is preferably 2-3 hours.

[0049] In this invention, the polyester polyol and isocyanate are weighed into a three-necked flask, heated and stirred in an oil bath at 60-80°C for 2-3 hours, and then the chain extender is added and stirred at 60-80°C for another 2-3 hours to carry out the prepolymerization reaction, thereby obtaining the polyurethane prepolymer.

[0050] After obtaining the polyurethane prepolymer, the present invention mixes the polyurethane prepolymer, 1-vinyl-2-pyrrolidone, photoinitiator and polymerization inhibitor to obtain the 4D printed invisible orthodontic device material based on shape memory polymer.

[0051] In this invention, the mass ratio of the polyurethane prepolymer to 1-vinyl-2-pyrrolidone is preferably 1 to 3:3 to 1, specifically 3:1, 2:1, 3:2, 1:1, 1:2 or 1:3.

[0052] In this invention, the amount of photoinitiator is preferably 0.5% of the sum of the mass of the polyurethane prepolymer and 1-vinyl-2-pyrrolidone, and the amount of polymerization inhibitor is preferably 0.15% of the sum of the mass of the polyurethane prepolymer and 1-vinyl-2-pyrrolidone.

[0053] In this invention, the polyurethane prepolymer is preferably dissolved in 1-vinyl-2-pyrrolidone, stirred at 60-80°C for 1 hour, and then the photoinitiator and polymerization inhibitor are added. The mixture is then stirred evenly at 60-80°C. The resulting solution is then degassed in a vacuum oven at 60-80°C until all bubbles are removed, thus obtaining the 4D printed invisible orthodontic material, which is then taken out for use.

[0054] The present invention also provides the application of the shape memory polymer-based 4D printed invisible aligner material described in the above technical solution or the shape memory polymer-based 4D printed invisible aligner material prepared by the preparation method described in the above technical solution in the preparation of oral invisible aligners.

[0055] The present invention also provides a 4D printed invisible orthodontic appliance, which is obtained by 4D printing from the 4D printed invisible orthodontic appliance material based on shape memory polymer as described in the above technical solution or the 4D printed invisible orthodontic appliance material based on shape memory polymer prepared by the preparation method described in the above technical solution.

[0056] In this invention, the preferred parameters for 4D printing include: ultraviolet light wavelength of 350-400nm, irradiation time of 10-30s per layer (specifically 10, 20, or 30s per layer), and printing temperature of 20-60℃ (specifically 20, 30, 40, 50, or 60℃); during the 4D printing process, a photoinitiated polymerization reaction occurs to form a polyurethane-based thermally responsive shape memory polymer.

[0057] 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.

[0058] Example 1

[0059] Take 30 parts by mass of polycarbonate diol (number average molecular weight of 1000) and 60 parts by mass of hexamethylene diisocyanate in a three-necked flask, heat and stir in an oil bath at 60°C for 3 hours, then add 60 parts by mass of hydroxyethyl methacrylate and continue stirring at 60°C for 3 hours to obtain polyurethane prepolymer. Then, 150 parts by mass of the prepared polyurethane prepolymer were dissolved in 50 parts by mass of 1-vinyl-2-pyrrolidone. After stirring at 80°C for 1 hour, 1 part by mass of photoinitiator 2,4,6-trimethylbenzoyl-diphenylphosphine oxide and 0.3 parts by mass of polymerization inhibitor hydroquinone were added. The mixture was stirred evenly at 80°C. The resulting solution was then degassed in a vacuum oven at 80°C until all bubbles were removed. The solution was then 4D printed for later use. A portion of the solution was photocured to form a film (UV wavelength range of 350-400nm) (denoted as PU3NVP1, where PU refers to polyurethane prepolymer, NVP is 1-vinyl-2-pyrrolidone, and the subscripts refer to the mass ratio. PU3NVP1 means that the mass ratio of PU to NVP is 3:1). The film was tested for later use and is a polyurethane-based thermoresponsive shape memory polymer.

[0060] Example 2

[0061] Similar to Example 1, the only difference is that the mass ratio of PU to NVP is 2:1, while ensuring that the amount of photoinitiator is 0.5% of the sum of the mass of polyurethane prepolymer and 1-vinyl-2-pyrrolidone, and the amount of polymerization inhibitor is 0.15% of the sum of the mass of polyurethane prepolymer and 1-vinyl-2-pyrrolidone. The photocured film is denoted as PU2NVP1.

[0062] Example 3

[0063] Similar to Example 1, the only difference is that the mass ratio of PU to NVP is 3:2, while ensuring that the amount of photoinitiator is 0.5% of the sum of the mass of polyurethane prepolymer and 1-vinyl-2-pyrrolidone, and the amount of polymerization inhibitor is 0.15% of the sum of the mass of polyurethane prepolymer and 1-vinyl-2-pyrrolidone. The photocured film is denoted as PU3NVP2.

[0064] Example 4

[0065] Similar to Example 1, the only difference is that the mass ratio of PU to NVP is 1:1, while ensuring that the amount of photoinitiator is 0.5% of the sum of the mass of polyurethane prepolymer and 1-vinyl-2-pyrrolidone, and the amount of polymerization inhibitor is 0.15% of the sum of the mass of polyurethane prepolymer and 1-vinyl-2-pyrrolidone. The photocured film is denoted as PU1NVP1.

[0066] Example 5

[0067] Similar to Example 1, the only difference is that the mass ratio of PU to NVP is 1:2, while ensuring that the amount of photoinitiator is 0.5% of the sum of the mass of polyurethane prepolymer and 1-vinyl-2-pyrrolidone, and the amount of polymerization inhibitor is 0.15% of the sum of the mass of polyurethane prepolymer and 1-vinyl-2-pyrrolidone. The photocured film is denoted as PU1NVP2.

[0068] Example 6

[0069] Similar to Example 1, the only difference is that the mass ratio of PU to NVP is 1:3, while ensuring that the amount of photoinitiator is 0.5% of the sum of the mass of polyurethane prepolymer and 1-vinyl-2-pyrrolidone, and the amount of polymerization inhibitor is 0.15% of the sum of the mass of polyurethane prepolymer and 1-vinyl-2-pyrrolidone. The photocured film is denoted as PU1NVP3.

[0070] Shape Memory Demonstration

[0071] The glass transition temperature (Tg) of the materials in the examples was tested using DMA (242C), and the measured Tg range of the samples was -22.5 to 113.8 °C. Figure 1 Oral temperature (36.3–37.5℃) falls within the above range. Figure 2 The bar chart shows the glass transition temperature of the material obtained by the present invention, illustrating that the material of the present invention can exhibit a shape memory effect at oral temperature.

[0072] The thermal response shape memory of the materials prepared in Examples 1-6 was demonstrated at a temperature of 37°C. See details below. Figure 3 As shown, the material exhibits a shape memory effect. In the example, the sample was folded in hot water at 70-80°C, fixed to a temporary shape in ice water at 0°C, and then placed in an oven at 37°C. The sample slowly recovered its shape, with a shape recovery rate of up to 80% within 4 days.

[0073] Mechanical properties

[0074] The mechanical properties of the materials prepared in the examples were tested at room temperature using a Shimadzu AG-X (5000N) electronic universal testing machine. The tensile speed was 1 mm / min. The sample shape was cut into dumbbell shape according to the international standard ISO-527-2 / 5B, and the average value of three samples was taken. The yield stress of Examples 5 and 6 was found to be >30 MPa, yield strain >4%, and elastic modulus >1500 MPa, which meets the industry standard for tensile properties in "Dental Orthodontic Appliance Membranes" (YY / T 1819-2022). See details. Figure 4 As shown, Figure 4 The image on the right is a partially enlarged view.

[0075] 4D printing

[0076] The invisible orthodontic appliance was modeled using computer modeling software (4DMAX, CAD, Solidworks, Blender, etc.), and then sliced ​​using slicing software. The material from Example 5 was selected for Digital Light Processing (DLP) and Stereolithography Appearance (SLA). The 4D printing process used was irradiation with 350–400 nm wavelength ultraviolet light for 10 seconds per layer, with a printing chamber temperature of 60°C. The 4D printing effect is shown in the image. Figure 5 As shown, the 3D aligners produced by printing have a certain degree of precision.

[0077] In summary, the materials of Examples 1 to 6 meet the requirements for being invisible orthodontic appliance materials with shape memory properties, and Example 5 meets the industry standard requirements for orthodontic appliance films.

[0078] Comparative example

[0079] Commonly used invisible aligner materials on the market were used as comparative examples (Angel Invisalign hard version was comparative example 1, Angel Invisalign soft version was comparative example 2, and Invisalign was comparative example 3). After being cut into samples, they were tested by differential scanning calorimetry (DSC).

[0080] The glass transition temperature of the comparative example was determined using a DSC STA449F3 (NETZSCH, Germany). The tests were conducted under a nitrogen atmosphere. The DSC tests followed this procedure: the sample was heated from room temperature to 100°C to eliminate the influence of thermal history. Subsequently, the sample was cooled to -100°C and then heated to 100°C. The heating / cooling rate for the entire process was set to 10°C / min. The second heating stage was used to evaluate the glass transition temperature of the material.

[0081] Figure 6 The DSC curve is for comparison.

[0082] Table 1 shows the specific data of glass transition temperature for the examples and comparative examples. It can be seen that the invisible orthodontic material designed by the present invention can exhibit shape memory effect within the oral temperature range (36.3~37.5℃). The polymer of the present invention is a thermally responsive shape memory polymer, composed of a reversible phase and a fixed phase. The fixed phase plays the role of maintaining the original shape, which is generally undertaken by the physical or chemical cross-linking points in the material. The reversible phase plays the role of maintaining a temporary shape, which is undertaken by the melting-crystallization or amorphous-glass transition process of the polymer chain segments. When heated to the melting point or glass transition temperature of the reversible phase, the reversible phase chain segments can move freely and can be shaped at this time. Then, by cooling, the molecular chains are crystallized or glassened to fix the reversible phase and obtain a temporary shape. When the temperature is raised again to exceed the melting point or glass transition temperature of the reversible phase, driven by entropy change, the chain segments move freely again and tend to return to the free state, and the material returns to the original shape. The melting point of the reversible phase of the polyurethane-based thermally responsive shape memory polymer of the present invention is located within the oral temperature range or its glass transition temperature includes the oral temperature range.

[0083] Table 1 Glass transition temperatures of the examples and comparative examples.

[0084] Glass transition temperature / °C Is it within the oral temperature range? Comparative Example 1 95.76 no Comparative Example 2 85.92 no Comparative Example 3 112.91 no Glass transition region / °C Is it within the oral temperature range? Example 1 -15.6～64.1 yes Example 2 -15.5～71.4 yes Example 3 -22.5～84.3 yes Example 4 -7.3～100 yes Example 5 -5.4～113.8 yes Example 6 -7.6～109.2 yes

[0085] 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. A 4D-printed invisible orthodontic material based on shape memory polymer, characterized in that, It is prepared from raw materials comprising the following parts by weight: 100-500 parts polyester polyol, 400-800 parts isocyanate, 400-800 parts chain extender, 200-4800 parts 1-vinyl-2-pyrrolidone, 5-35 parts photoinitiator, and 1-15 parts polymerization inhibitor; wherein the chain extender comprises hydroxyethyl methacrylate and / or dimethylaminoethyl methacrylate; The method for preparing the 4D-printed invisible orthodontic appliance material based on shape memory polymer includes the following steps: Weigh the polyester polyol and isocyanate into a three-necked flask, heat and stir in an oil bath at 60-80°C for 2-3 hours, then add the chain extender and continue stirring at 60-80°C for 2-3 hours to carry out the prepolymerization reaction, and obtain the polyurethane prepolymer. The polyurethane prepolymer, 1-vinyl-2-pyrrolidone, photoinitiator and polymerization inhibitor are mixed to obtain the 4D printed invisible orthodontic material based on shape memory polymer; The mass ratio of the polyurethane prepolymer to 1-vinyl-2-pyrrolidone is 3:

1.

2. The 4D-printed invisible orthodontic material according to claim 1, characterized in that, The polyester polyols include polyethylene terephthalate-1,4-cyclohexanediol and / or polycarbonate diols.

3. The 4D-printed invisible orthodontic material according to claim 2, characterized in that, The number average molecular weight of the polycarbonate diol is 1000~2000.

4. The method for preparing the 4D-printed invisible orthodontic appliance material based on shape memory polymer according to any one of claims 1 to 3, characterized in that, Includes the following steps: Weigh the polyester polyol and isocyanate into a three-necked flask, heat and stir in an oil bath at 60-80°C for 2-3 hours, then add the chain extender and continue stirring at 60-80°C for 2-3 hours to carry out the prepolymerization reaction, and obtain the polyurethane prepolymer. The polyurethane prepolymer, 1-vinyl-2-pyrrolidone, photoinitiator and polymerization inhibitor are mixed to obtain the 4D printed invisible orthodontic material based on shape memory polymer; The mass ratio of the polyurethane prepolymer to 1-vinyl-2-pyrrolidone is 3:

1.

5. The preparation method according to claim 4, characterized in that, The prepolymerization reaction is carried out at a temperature of 60-80°C for 2-3 hours.

6. The application of the 4D-printed invisible aligner material based on shape memory polymer as described in any one of claims 1 to 3, or the 4D-printed invisible aligner material based on shape memory polymer prepared by the preparation method described in any one of claims 4 to 5, in the preparation of invisible aligners.

7. A 4D-printed invisible orthodontic appliance, characterized in that, The 4D-printed invisible orthodontic appliance material based on shape memory polymer as described in any one of claims 1 to 3, or the 4D-printed invisible orthodontic appliance material based on shape memory polymer prepared by the preparation method described in any one of claims 4 to 5, is obtained by 4D printing.

8. The 4D-printed invisible orthodontic appliance according to claim 7, characterized in that, The parameters for 4D printing include: ultraviolet light wavelength of 350~400nm, irradiation time of 10~30s / layer, and printing temperature of 20~60℃.

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