Gray scale controlled 3D printing appliance step solidification method

Abstract

The application discloses a kind of based on gray scale control 3D printing appliance step-by-step solidification method.The method includes: the light-sensitive resin used is prepared, and the light-sensitive resin includes epoxy acrylate component, a certain amount of thermal initiator is added in the light-sensitive resin;The region corresponding to the specified tooth is segmented from the 3D printing model of appliance, and the pattern gray scale of the region corresponding to the specified tooth is modified;The 3D printing model of appliance is sliced, and a plurality of slice patterns with gray scale processing are obtained;Based on a plurality of slice patterns, the gray scale photocuring treatment of each layer of appliance is completed;The appliance after gray scale photocuring treatment is placed in oven to heat for specified time at specified temperature.The application is based on gray scale control, uses photocuring, thermal curing step-by-step solidification scheme in the process of 3D printing appliance, reduces the internal monomer amount while guaranteeing the mechanical property of 3D printing appliance, can effectively reduce the precipitation of monomer, and improve biocompatibility.

Description

Technical Field

[0001] This invention relates to the field of 3D printing technology, and in particular to a stepwise curing method and system for 3D printed orthodontic appliances based on grayscale control. Background Technology

[0002] During growth and development, malocclusion can occur due to congenital factors, acquired diseases, or bad habits. Problems such as misaligned teeth, abnormal bite, and abnormal jaw size, shape, and position are collectively referred to as malocclusion. It can affect oral health, leading to periodontal inflammation and other issues. Clinically, malocclusion is treated by wearing orthodontic appliances.

[0003] Clear aligners are a new type of orthodontic treatment. Compared to traditional metal braces, clear aligners have rapidly gained popularity in my country due to their aesthetic appeal, comfort, and shorter treatment duration, and their market share is gradually increasing. Currently, the mainstream manufacturing method for clear aligners is thermoforming. This technology involves creating a 3D printed dental model, then heating and pressing a thermoplastic film onto the model to form the aligner. However, compared to the original size of the film, the thermoforming process results in uneven thickness, which can affect its mechanical properties and clinical treatment outcomes.

[0004] With the continuous development of 3D printing technology and biocompatible materials, direct 3D printing of orthodontic appliances is considered the next stage in orthodontic appliance manufacturing. Compared to thermoforming, direct 3D printing improves the manufacturing precision of orthodontic appliances and reduces resource waste and time costs. However, invisible aligners have significant limitations when dealing with complex orthodontic forces, such as difficulty in controlling torque and root resorption. Therefore, an effective method is needed to help orthodontic appliances provide adjustable orthodontic forces to ensure that teeth move in the correct position and prevent excessive orthodontic forces from causing damage to the periodontal tissues around the moving teeth.

[0005] Grayscale photopolymerization printing is a rapidly developing manufacturing technology in recent years. It can achieve different material properties by controlling the degree of local material crosslinking. Using grayscale printing to manufacture orthodontic appliances can overcome the shortcomings of single-material properties in 3D printed orthodontic appliances, and can adapt to more complex orthodontic cases. However, because 3D printing resin is biotoxic before it is fully polymerized, secondary curing and processing must be carried out to eliminate the potential toxicity of 3D printed orthodontic appliances, thus limiting the application of grayscale printing.

[0006] Regarding grayscale photopolymer printing, existing technologies have proposed a method based on two-color photopolymerization. While this method can reduce monomer precipitation within the printed body to some extent, it does not reduce the total amount of monomers within the printed body. Existing technologies have also proposed using photodegradable monomers, which decompose after prolonged exposure, thereby increasing bioactivity. However, this method leads to a decrease in the mechanical properties of the printed body.

[0007] How to reduce the amount of monomer inside the printed body while ensuring the mechanical properties of the printed body has become an urgent problem to be solved. Summary of the Invention

[0008] In view of the above problems, the present invention is proposed to provide a step-by-step curing method and system for 3D printed orthodontic appliances based on grayscale modulation to overcome or at least partially solve the above problems.

[0009] An embodiment of the present invention provides a step-by-step curing method for 3D printed orthodontic appliances based on grayscale modulation, the method comprising:

[0010] Prepare the photosensitive resin, which contains an epoxy acrylate component, and add a certain amount of thermal initiator to the photosensitive resin;

[0011] The region corresponding to the specified tooth is segmented from the 3D printed model of the orthodontic appliance, and the grayscale of the pattern corresponding to the specified tooth is modified.

[0012] The 3D printed model of the orthodontic appliance is sliced ​​to obtain multiple slice patterns with grayscale processing.

[0013] The grayscale photocuring process of each layer of the orthodontic appliance is completed based on multiple slice patterns;

[0014] The orthodontic appliance, after grayscale photocuring, is placed in an oven and heated at a specified temperature for a specified time to complete the thermocuring process.

[0015] In the photosensitive resin, the carbon-carbon double bond functionality of the epoxy acrylate component is greater than that of the epoxy group functionality.

[0016] Optionally, the preparation of the photosensitive resin includes:

[0017] The thermal initiator and photosensitive resin are added to a light-proof container, and then placed in a stirrer for thorough stirring to obtain a stirred mixture. The stirred mixture is then placed in an ultrasonic cleaner for ultrasonic dispersion to completely dissolve the thermal initiator in the photosensitive resin, thus obtaining a photosensitive resin for printing.

[0018] Optionally, the epoxy acrylate component is composed of one or more of the following: bisphenol A glycidyl methacrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate, and neopentyl glycol diglycidyl ether diacrylate.

[0019] Optionally, the ratio of the thermal initiator to the photosensitive resin by weight is 0.2-2 parts.

[0020] Optionally, the thermal initiator is one or two of the following: dimethyl azobisisobutyrate, nitrile diisoheptanenitrile, tert-butyl peroxide-2-ethylhexanoate, 593 curing agent, T31 curing agent, 1-methylimidazole, and diisopropyl peroxide dicarbonate.

[0021] Optionally, modifying the grayscale of the region corresponding to the specified tooth includes:

[0022] Adjust the gray level of the area corresponding to the specified tooth to be increased or decreased.

[0023] Optionally, reducing the grayscale of the region corresponding to the specified tooth includes:

[0024] Reduce the grayscale of the area corresponding to the specified tooth by 40%-60%.

[0025] Optionally, when the grayscale of the region corresponding to the specified tooth is reduced, the method further includes:

[0026] Obtain the surface pixels of the specified tooth, and restore the grayscale value of the surface pixels of the specified tooth to its original value.

[0027] Optionally, obtaining the surface pixels of the specified tooth includes:

[0028] Obtain the edges of each slice pattern corresponding to the specified tooth, where the edges of each slice pattern corresponding to the specified tooth are the surface pixels in the horizontal direction of the specified tooth;

[0029] The vertical surface pixels of the specified tooth are obtained based on the difference in grayscale values ​​of each pixel in the adjacent slice patterns.

[0030] Optionally, the grayscale photocuring process for each layer of the orthodontic appliance based on multiple slice patterns includes:

[0031] The grayscale photocuring process of each layer of the orthodontic appliance is completed using UV light based on multiple slice patterns.

[0032] Optionally, the oven is heated to a specified temperature of 60-120℃ for a specified time of 1-12 hours.

[0033] Another embodiment of the present invention provides a step-by-step curing system for 3D printed orthodontic appliances based on grayscale control, which employs the step-by-step curing method for 3D printed orthodontic appliances based on grayscale control as described above.

[0034] The beneficial effects of this invention are that by modifying the grayscale of a specific tooth-corresponding region in the clear aligner model, and controlling the degree of cross-linking in that region using changes in light intensity, the Young's modulus of that region changes, creating regions with varying degrees of hardness. This means that the orthodontic force can be customized, thereby achieving the effect of regulating the orthodontic force. This invention does not modify the thickness of the aligner model, meaning a uniform thickness; by controlling the grayscale, a larger orthodontic range can be achieved during treatment without causing patient discomfort. Based on grayscale control, this invention adds a thermal initiator to the photosensitive resin used and employs a step-by-step curing scheme of photocuring and thermal curing during the 3D printing process. This reduces the amount of monomers inside while ensuring the mechanical properties of the 3D printed aligner, effectively reducing monomer precipitation and improving biocompatibility. Attached Figure Description

[0035] Figure 1 This is a schematic flowchart of a stepwise curing method for 3D printed orthodontic appliances based on grayscale control, according to an embodiment of the present invention.

[0036] Figure 2 This is a schematic diagram illustrating the principle of a step-by-step curing method for 3D printed orthodontic appliances based on grayscale control, according to an embodiment of the present invention.

[0037] Figure 3 This is a schematic diagram illustrating the principle of a step-by-step curing system for a 3D-printed orthodontic appliance based on grayscale control, according to an embodiment of the present invention.

[0038] Figure 4 This is a schematic diagram of obtaining an orthodontic appliance from a 3D printed model based on an embodiment of the present invention. Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0040] Figure 1 This is a schematic flowchart of a step-by-step curing method for 3D printed orthodontic appliances based on grayscale control, according to an embodiment of the present invention. Figure 1 As shown, the method of this embodiment of the invention includes:

[0041] S11: Prepare the photosensitive resin to be used, wherein the photosensitive resin contains an epoxy acrylate component and a certain amount of thermal initiator is added to the photosensitive resin;

[0042] In the photosensitive resin, the carbon-carbon double bond functionality of the epoxy acrylate component is greater than that of the epoxy group functionality.

[0043] S12: Segment the region corresponding to the specified tooth from the 3D printed model of the orthodontic appliance, and modify the grayscale of the pattern of the region corresponding to the specified tooth;

[0044] Understandably, the basic principle of this invention is to adjust the influence on the corrective force by modifying the local modulus of the orthodontic appliance model using grayscale. During the model preprocessing, the corrective force in a local area of ​​the orthodontic appliance model needs to be adjusted as needed, and the grayscale of that area is modified accordingly.

[0045] S13: Slice the 3D printed model of the orthodontic appliance to obtain multiple slice patterns with grayscale processing;

[0046] In practical applications, 3D printing software is used to slice the model to obtain multiple slice patterns. The grayscale value in the slice pattern is positively correlated with the light intensity value of the projected pattern light; a higher grayscale value indicates higher light intensity, which means the resin receives more energy and achieves a higher degree of curing.

[0047] S14: Complete the grayscale photocuring process of each layer of the orthodontic appliance based on multiple slice patterns;

[0048] S15: Place the orthodontic appliance, after grayscale light curing, into an oven and heat it at a specified temperature for a specified time to complete the thermosetting operation.

[0049] In this embodiment of the invention, a thermal initiator is added to the photosensitive resin used. In the first stage, grayscale photocuring is performed to regulate the mechanical properties of the orthodontic appliance. In the second stage, the orthodontic appliance is placed in an oven for thermal curing.

[0050] It should be noted that the photosensitive resin used in this embodiment of the invention contains an epoxy acrylate component, which simultaneously possesses the rapid curing speed of acrylate and the low shrinkage and good mechanical properties of epoxy resin. During the first stage of photocuring, under light irradiation, the photoinitiator in the photosensitive resin decomposes to generate free radicals. These newly formed free radicals diffuse into the resin medium and polymerize with the acrylate monomers to form a cross-linked network. In the second stage, heating triggers the polymerization reaction of the epoxy groups, further increasing the cross-linking density. Due to the difference between the two reaction mechanisms, an interpenetrating polymer network forms inside the printed structure. The monomers in the resin used have epoxy groups and carbon-carbon double bond groups that can participate in the polymerization reaction. In the photocuring reaction, the carbon-carbon double bonds participate in the reaction, while in the thermocuring conditions, the epoxy groups participate. In the first stage of photocuring, the local grayscale of the projected pattern is adjusted to change the local light intensity, thereby controlling the degree of local cross-linking of the orthodontic appliance. (The degree of local crosslinking here refers to the crosslinking network formed by the monomers through carbon-carbon double bond reactions; epoxy groups do not participate in the reaction under light.) In the second stage of thermosetting, the thermal initiator generates active groups that polymerize with the epoxy groups in the components. (The carbon-carbon double bonds do not participate in this reaction, so these two reactions do not affect each other and are orthogonal.) With the polymerization of epoxy groups, the overall crosslinking density continuously increases. Because the carbon-carbon double bond functionality of the epoxy acrylate component in the photosensitive resin is greater than the epoxy group functionality, compared to thermosetting, photosetting can form a denser crosslinking network due to the greater number of functional groups participating in the reaction.

[0051] The following combination Figure 2 This invention explains the principle of the step-by-step curing method for 3D printed orthodontic appliances based on grayscale control in this embodiment. Figure 2 The left image shows the first stage of photocuring treatment of the photosensitive resin used, with the left projection set to 100% grayscale and the right image set to 50% grayscale. Since thermal curing does not occur, the resulting network is entirely a photocured cross-linked network. Furthermore, the network on the left is denser than the network on the right, with less residual monomer content in some areas. Figure 2 The right image shows the second-stage thermosetting treatment of the photosensitive resin. Since the 50% grayscale projection side has more unreacted monomers, the thermosetting network mainly forms on the grayscale side. Ultimately, under grayscale photocuring, photothermal cross-linked interpenetrating networks with different degrees of cross-linking can be formed. Because the thermosetting cross-linked network is more flexible than the photocured network, the advantages of grayscale printing in controlling mechanical properties can be effectively retained. Furthermore, because the thermosetting process further increases the degree of cross-linking, the monomer content inside the print body can be effectively reduced, thereby reducing monomer precipitation and improving the biocompatibility of the print body.

[0052] This invention modifies the grayscale of a specific area corresponding to a tooth in a clear aligner model, using variations in light intensity to control the degree of cross-linking in that area. This alters the Young's modulus of that area, creating regions of varying hardness. This allows for customized design of the orthodontic force, thus achieving control over the force applied. The invention does not modify the thickness of the aligner model, ensuring uniform thickness. By controlling the grayscale, greater orthodontic volume can be achieved without causing patient discomfort. Based on grayscale control, this invention adds a thermal initiator to the photosensitive resin and employs a step-by-step curing scheme of photocuring and thermal curing during 3D printing. This reduces the amount of monomers inside while maintaining the mechanical properties of the 3D printed aligner, effectively reducing monomer precipitation and improving biocompatibility.

[0053] In an optional embodiment of the present invention, the preparation of the photosensitive resin includes:

[0054] The thermal initiator and photosensitive resin are added to a light-proof container, and then placed in a stirrer for thorough stirring to obtain a stirred mixture. The stirred mixture is then placed in an ultrasonic cleaner for ultrasonic dispersion to completely dissolve the thermal initiator in the photosensitive resin, thus obtaining a photosensitive resin for printing.

[0055] In practical applications, the stirring time can be 10 minutes, and the ultrasonic dispersion time can be 15 minutes.

[0056] In practical applications, the epoxy acrylate component is composed of one or more of the following: bisphenol A glycidyl methacrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate, and neopentyl glycol diglycidyl ether diacrylate.

[0057] The ratio of the thermal initiator to the photosensitive resin by weight is 0.2-2 parts.

[0058] The thermal initiator is one or two of the following: dimethyl azobisisobutyrate, nitrile diisoheptanenitrile, tert-butyl peroxide-2-ethylhexanoate, 593 curing agent, T31 curing agent, 1-methylimidazole, and diisopropyl peroxide dicarbonate.

[0059] Another embodiment of the present invention provides a step-by-step curing system for 3D-printed orthodontic appliances based on grayscale control, employing the step-by-step curing method for 3D-printed orthodontic appliances based on grayscale control as described above. In practical applications, the hardware structure of the 3D-printed orthodontic appliance system can utilize existing technologies.

[0060] Figure 3This is a schematic diagram illustrating the principle of a step-by-step curing system for 3D-printed orthodontic appliances based on grayscale control, according to an embodiment of the present invention. To better understand the technical solution of this embodiment, the following is combined with... Figure 3 Please provide an explanation.

[0061] like Figure 3 As shown, the 3D printed orthodontic appliance step-by-step curing system of this embodiment includes a stepper motor 1, a guide rail 2, a printing platform 3, a material tank 5 containing photosensitive resin 4, a reflector 6, a motor driver 7, a display 8, a DLP optical engine 9, and a control motherboard 10. The stepper motor 1 controls the movement of the printing platform 3; the guide rail 2 restricts the movement direction of the printing platform 3, allowing it to move vertically; the printing platform 3 is connected to the guide rail 2 via a crossbeam, and the printed body is formed on the printing platform 3; the reflector 6 reflects the projected light to the bottom of the material tank 5; the motor driver 7 drives the stepper motor 1; the display 8 provides an operating interface; the DLP optical engine 9 projects pattern light; and the control motherboard 10 controls the overall 3D printing process. The operator can operate the system via the display 8 to set printing parameters, including the printing platform's moving speed, moving distance, set layer thickness, and DLP optical engine exposure time. The printing platform's moving speed and distance affect the printing success rate, while the layer thickness affects the vertical printing accuracy. Exposure time influences both success rate and accuracy; insufficient exposure may lead to layer adhesion failure due to inadequate resin curing, while excessive exposure may result in over-curing and affect printing accuracy. The control motherboard 10 transmits the sliced ​​pattern to the DLP optical engine 9 and projects it. After a certain exposure time, the photosensitive resin corresponding to the pattern inside the feed tank 5 cures, and the DLP optical engine 9 shuts off. Subsequently, the stepper motor 1 receives a control command and begins to move upwards, causing the cured resin to detach from the bottom of the feed tank 5, completing one layer of printing. The DLP optical engine then projects the next sliced ​​pattern and undergoes the same process, ultimately producing a grayscale orthodontic device.

[0062] Specifically, modifying the grayscale of the region corresponding to the specified tooth includes:

[0063] Adjust the gray level of the area corresponding to the specified tooth to be increased or decreased.

[0064] The grayscale value in the slice pattern is positively correlated with the light intensity of the projected pattern light; a higher grayscale value indicates higher light intensity, meaning the resin receives more energy and achieves a higher degree of curing. When the grayscale value of a specific tooth's corresponding area is lowered, the light intensity in that area decreases, resulting in a slower curing degree of the photosensitive resin and thus a reduced modulus. Conversely, when the grayscale value of a specific tooth's corresponding area is increased, the light intensity in that area increases, leading to a faster curing degree of the photosensitive resin and thus an increased modulus.

[0065] Modulus is directly proportional to orthodontic force. Based on grayscale modification, the modulus of a specified tooth area is adjusted, and the orthodontic force is also controlled.

[0066] Furthermore, the step of lowering the grayscale of the region corresponding to the specified tooth includes:

[0067] Reduce the grayscale of the area corresponding to the specified tooth by 40%-60%.

[0068] Preferably, the grayscale of the area corresponding to the specified tooth is reduced by 50%.

[0069] Furthermore, when the grayscale of the area corresponding to a specified tooth is reduced, it also includes:

[0070] Obtain the surface pixels of the specified tooth, and restore the grayscale value of the surface pixels of the specified tooth to its original value.

[0071] Understandably, considering the biotoxicity of photosensitive resins, and the fact that higher curing levels reduce toxicity, it is necessary to increase the surface curing degree of the orthodontic appliance. During grayscale conversion of the model, a reduction in the grayscale value of a specified tooth area leads to a decrease in the curing degree of that area, thus increasing its biotoxicity. Therefore, it is necessary to enhance the surface curing degree of the areas where grayscale values ​​are modified. The approach to this process is to first obtain the surface pixels of the specified tooth, restore the grayscale values ​​of these surface pixels to their original values, thereby increasing the exposure and enhancing the surface curing degree of the modified area.

[0072] Specifically, obtaining the surface pixels of the specified tooth includes:

[0073] Obtain the edges of each slice pattern corresponding to the specified tooth, where the edges of each slice pattern corresponding to the specified tooth are the surface pixels in the horizontal direction of the specified tooth;

[0074] The vertical surface pixels of the specified tooth are obtained based on the difference in grayscale values ​​of each pixel in the adjacent slice patterns.

[0075] Understandably, obtaining the surface pixels in the vertical direction requires calculating the difference in grayscale values ​​between pixels in two adjacent slice patterns. For example, if pixel A is a surface pixel of the model, then the corresponding pixel B in the adjacent slice pattern has a grayscale value of 0. This means there is no pattern at pixel B, indicating that pixel A is also on the model surface. Therefore, by subtracting the values ​​of two slices of the model, if it is the model surface, the difference between the corresponding pixels is the absolute value of pixel A. Then, based on a set grayscale value of 50%, pixels whose difference matches the 50% grayscale value are selected; these pixels represent the surface area of ​​the model in the vertical direction.

[0076] After obtaining the surface pixels of the model, the grayscale value is modified back to 100%. The purpose of this operation is to increase the surface light transmittance of the printed orthodontic appliance and improve the surface curing degree.

[0077] In practical applications, the grayscale photocuring process for each layer of the orthodontic appliance based on multiple slice patterns includes:

[0078] The grayscale photocuring process of each layer of the orthodontic appliance is completed using UV light based on multiple slice patterns.

[0079] Preferably, the oven is heated to a specified temperature of 60-120℃ for a specified time of 1-12 hours.

[0080] Figure 4 This is a schematic diagram illustrating the 3D-printed model of an orthodontic appliance obtained according to an embodiment of the present invention. Figure 4 As shown, Figure 4 On the left is a 3D printed model of the orthodontic appliance. The six teeth in the middle are designated teeth with their grayscale level reduced by 50%, while the grayscale level of the remaining teeth is not adjusted. Using the method described above, the first stage involves UV light curing to control the mechanical properties of the appliance. The second stage involves placing the appliance in an oven for heat curing, thereby obtaining the desired result. Figure 4 The printed orthodontic appliance is shown on the right.

[0081] It should be noted that:

[0082] Numerous specific details are set forth in the specification provided herein. However, it will be understood that embodiments of the invention may be practiced without these specific details. In some instances, well-known methods, structures, and techniques have not been shown in detail so as not to obscure the understanding of this specification.

[0083] Similarly, it should be understood that, in order to simplify the invention and aid in understanding one or more of the various inventive aspects, in the above description of exemplary embodiments of the invention, various features of the invention are sometimes grouped together in a single embodiment, figure, or description thereof. However, this disclosure should not be construed as reflecting an intention that the claimed invention requires more features than are expressly recited in each claim. Rather, as reflected in the following claims, inventive aspects lie in fewer than all features of a single foregoing disclosed embodiment. Therefore, the claims following the detailed description are hereby expressly incorporated into this detailed description, wherein each claim itself is a separate embodiment of the invention.

[0084] Furthermore, those skilled in the art will understand that although some embodiments described herein include certain features included in other embodiments but not others, combinations of features from different embodiments are meant to be within the scope of the invention and form different embodiments.

[0085] The above description is merely a specific embodiment of the present invention. Under the teachings of the present invention, those skilled in the art can make other improvements or modifications based on the above embodiments. Those skilled in the art should understand that the above specific description is only to better explain the purpose of the present invention, and the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A step-by-step curing method for 3D-printed orthodontic appliances based on grayscale modulation, characterized in that, include: Prepare the photosensitive resin, which contains an epoxy acrylate component, and add a certain amount of thermal initiator to the photosensitive resin; The region corresponding to the specified tooth is segmented from the 3D printed model of the orthodontic appliance, and the grayscale of the pattern corresponding to the specified tooth is modified. The 3D printed model of the orthodontic appliance is sliced ​​to obtain multiple slice patterns with grayscale processing. The grayscale photocuring process of each layer of the orthodontic appliance is completed based on multiple slice patterns; The orthodontic appliance, after grayscale photocuring, is placed in an oven and heated at a specified temperature for a specified time to complete the thermocuring process. In the photosensitive resin, the carbon-carbon double bond functionality of the epoxy acrylate component is greater than that of the epoxy group functionality. The ratio of the thermal initiator to the photosensitive resin by weight is 0.2-2 parts; Modifying the grayscale of the region corresponding to the specified tooth includes: Adjust the gray level of the area corresponding to the specified tooth to be higher or lower; The step of lowering the gray level of the region corresponding to the specified tooth includes: Reduce the gray level of the area corresponding to the specified teeth by 40%-60%.

2. The method for 3D printing an orthodontic appliance based on grayscale control according to claim 1, characterized in that, The photosensitive resin is prepared by: The thermal initiator and photosensitive resin are added to a light-proof container, and then placed in a stirrer for thorough stirring to obtain a stirred mixture. The stirred mixture is then placed in an ultrasonic cleaner for ultrasonic dispersion to completely dissolve the thermal initiator in the photosensitive resin, thus obtaining a photosensitive resin for printing.

3. The method for 3D printing an orthodontic appliance based on grayscale control according to claim 1, characterized in that, The epoxy acrylate component comprises one or more of the following: bisphenol A glycidyl methacrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate, and neopentyl glycol diglycidyl ether diacrylate.

4. The method for 3D printing an orthodontic appliance based on grayscale control according to claim 1, characterized in that, The thermal initiator is one or two of the following: dimethyl azobisisobutyrate, nitrile diisoheptanenitrile, tert-butyl peroxide-2-ethylhexanoate, 593 curing agent, T31 curing agent, 1-methylimidazole, and diisopropyl peroxide dicarbonate.

5. The method for 3D printing an orthodontic appliance based on grayscale control according to claim 1, characterized in that, In addition to lowering the grayscale of the area corresponding to a specified tooth, the following are also included: Obtain the surface pixels of the specified tooth, and restore the grayscale value of the surface pixels of the specified tooth to its original value.

6. The method for 3D printing an orthodontic appliance based on grayscale control according to claim 5, characterized in that, The step of obtaining the surface pixels of the specified tooth includes: Obtain the edges of each slice pattern corresponding to the specified tooth, where the edges of each slice pattern corresponding to the specified tooth are the surface pixels in the horizontal direction of the specified tooth; The vertical surface pixels of the specified tooth are obtained based on the difference in grayscale values ​​of each pixel in the adjacent slice patterns.

7. The method for 3D printing an orthodontic appliance based on grayscale control according to claim 1, characterized in that, The grayscale photocuring process for each layer of the orthodontic appliance based on multiple slice patterns includes: The grayscale photocuring process of each layer of the orthodontic appliance is completed using UV light based on multiple slice patterns.

8. The method for 3D printing an orthodontic appliance based on grayscale control according to claim 1, characterized in that, The oven heating temperature is specified as 60-120℃, and the specified time is 1-12h.

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