Orthodontic appliances and their use

Abstract

This invention discloses an orthodontic appliance and its application. The appliance includes a shell and a cavity. The shell includes a covering layer and a temperature-sensitive absorbent layer. The cavity formed by the covering layer is used to accommodate teeth. The temperature-sensitive absorbent layer is disposed in at least a portion of the surface of the covering layer near the teeth. The material of the temperature-sensitive absorbent layer includes a polymer whose hydrophilicity / hydrophobicity changes with temperature. This orthodontic appliance can simultaneously achieve the effects of secure wearing and easy removal.

Description

Technical Field

[0001] This invention relates to an orthodontic appliance and its application. Background Technology

[0002] The shape of the alveolar bone in invisible aligners differs slightly from the shape of natural teeth, and there may be issues such as short crowns, insufficient undercuts, missing teeth, or excessive saliva and food debris in the mouth, which can often lead to the aligners loosening and falling out. Therefore, during dental treatment, orthodontists will bond attachments to the patient's teeth to firmly fix the invisible aligners in place and ensure that the teeth move in the expected direction.

[0003] However, there are currently several problems with attachments: 1. Bonding attachments to the patient's teeth reduces the dentist's work efficiency; 2. There is a risk of attachments falling off during treatment; 3. It is difficult to remove attachments at the end of treatment; 4. Demineralization caries are more likely to occur around the attachments.

[0004] To address the aforementioned issues, patent application CN116942338A provides a method for preparing a suction cup structure during the hot-pressing process of an invisible aligner. This method reduces the need for attachments by generating an adhesive force between the suction cup structure and the teeth. Patent application CN219439483U describes a method for installing hollow suction components inside the aligner. The suction components are positioned inside the aligner corresponding to one of the user's teeth, and the suction components create negative pressure after degassing, generating an adhesive force with the teeth. However, these patents only focus on the fixation of the invisible aligner during wear; the adhesive force cannot be changed when it is removed, and the generation of negative pressure in each suction cup structure requires manual degassing, making the operation neither simple nor convenient. Summary of the Invention

[0005] To address the shortcomings of existing orthodontic appliances that cannot simultaneously achieve both secure fit and easy removal, this invention provides an orthodontic appliance and its application. This appliance can simultaneously achieve both secure fit and easy removal.

[0006] The present invention solves the above-mentioned technical problems through the following technical solutions.

[0007] The present invention provides an orthodontic appliance comprising a housing and a cavity. The housing includes a wrapping layer and a temperature-sensitive adsorption layer. The cavity formed by the wrapping layer is used to accommodate teeth. The temperature-sensitive adsorption layer is disposed in at least a portion of the surface of the wrapping layer near the teeth. The material of the temperature-sensitive adsorption layer includes a polymer whose hydrophilicity / hydrophobicity changes with temperature.

[0008] In this invention, the adsorption force between the temperature-sensitive adsorption layer and the teeth can be adjusted by changes in the external temperature, thereby changing the adsorption force between the orthodontic appliance and the teeth.

[0009] The thermosensitive adsorption layer is made of poly(N-isopropylacrylamide), abbreviated as PNIPAM, a thermosensitive polymer. Its thermosensitive principle is mainly based on the competition between the hydrophilic amide groups and the hydrophobic isopropyl groups near the lower critical solution temperature (LCST), leading to a change in hydrophilicity / hydrophobicity. The LCST of PNIPAM is approximately 32°C. Below this temperature, the hydration of the amide groups in PNIPAM dominates, exhibiting hydrophilicity and an extended chain conformation. When the temperature rises above the LCST, the hydrophobic effect of the isopropyl groups in PNIPAM becomes dominant, causing the polymer chains to physically coil, and the enhanced inter-chain interactions trigger phase separation. This change in polymer chain conformation near the LCST results in a significant change in polymer volume. Below the LCST, water molecules form hydrogen bonds with the amide groups of PNIPAM, causing the polymer to absorb water and swell. When the temperature rises above the LCST, the hydrogen bonds are broken, and the hydrophobic effect of the isopropyl groups repels water molecules, causing the polymer to shrink and its volume to decrease. Therefore, due to its thermosensitive volume swelling-shrinkage transformation, PNIPAM can generate internal negative pressure during shrinkage, enhancing its adsorption capacity with surrounding substances. PNIPAM's LCST is approximately 32°C, near human body temperature, thus allowing it to be applied to the human body to achieve thermosensitive adsorption force changes. Therefore, during the insertion and removal of orthodontic appliances, the thermosensitive adsorption layer can switch its adsorption force according to changes in ambient temperature, eliminating the need for attaching and removing attachments.

[0010] In this invention, preferably, the material of the temperature-sensitive adsorption layer includes poly(N-isopropylacrylamide) and / or poly(N-isopropylacrylamide) copolymer.

[0011] Preferably, the number average molecular weight of the poly(N-isopropylacrylamide) is 10,000-100,000, for example, 40,000.

[0012] Preferably, the number-average molecular weight of the poly(N-isopropylacrylamide) copolymer is 1,000-500,000, for example, 30,000.

[0013] Preferably, the poly(N-isopropylacrylamide) copolymer is formed by polymerization of poly(N-isopropylacrylamide) and a first monomer; the first monomer includes one or more of acrylic acid, acrylate and acrylamide.

[0014] Preferably, the mass ratio of the poly(N-isopropylacrylamide) to the first monomer is 1:(0.01-100).

[0015] In some specific embodiments of the present invention, the poly(N-isopropylacrylamide) copolymer is formed by polymerizing poly(N-isopropylacrylamide) and acrylic acid; the mass ratio of poly(N-isopropylacrylamide) to acrylic acid is 1:0.1.

[0016] In this invention, preferably, the LCST of the material of the thermosensitive adsorption layer is 25-45°C. Here, LCST refers to the temperature at which the hydrophilicity / hydrophobicity of the material of the thermosensitive adsorption layer changes.

[0017] In this invention, preferably, the peel strength of the temperature-sensitive adsorption layer below 25°C is less than 5 N / m, wherein the peel strength below 25°C means the peel strength between the temperature-sensitive adsorption layer and the tooth in an environment below 25°C.

[0018] Preferably, the peel strength of the temperature-sensitive adsorption layer at 20°C is below 5 N / m, where the peel strength below 20°C means the peel strength between the temperature-sensitive adsorption layer and the tooth at an environment of 20°C.

[0019] Preferably, the peel strength of the temperature-sensitive adsorption layer at 20°C is 1-5 N / m.

[0020] In this invention, preferably, the peel strength of the temperature-sensitive adsorption layer at 30-37°C is above 20 N / m, wherein the peel strength at 30-37°C means the peel strength between the temperature-sensitive adsorption layer and the tooth under normal oral environment (30-37°C).

[0021] Preferably, the peel strength of the temperature-sensitive adsorption layer at 37°C is above 20 N / m. Here, the peel strength at 37°C refers to the peel strength between the temperature-sensitive adsorption layer and the tooth at 37°C.

[0022] Preferably, the peel strength of the temperature-sensitive adsorption layer at 37°C is 20-1000 N / m.

[0023] In this invention, preferably, the hydrophilicity / hydrophobicity switching time of the material in the temperature-sensitive adsorption layer is less than 5 minutes. The hydrophilicity / hydrophobicity switching time of the material in the temperature-sensitive adsorption layer means the time elapsed when the external temperature changes from T1 to T2, during which the material in the temperature-sensitive adsorption layer changes from being predominantly hydrophilic to being predominantly hydrophobic, or vice versa.

[0024] The time it takes for the peel strength to change from 5 N / m to 20 N / m is defined as the time elapsed between the peel strength and the peel strength of the adsorption force.

[0025] In this invention, the method for preparing the orthodontic appliance may include the following steps: coating a solution onto at least a portion of the surface of the wrapping layer near the teeth, and then curing it to form a temperature-sensitive adsorption layer; wherein the solution includes the material and solvent of the temperature-sensitive adsorption layer.

[0026] The coating may be, for example, brushing, spraying, spin coating, or dip coating.

[0027] The solvent is, for example, water.

[0028] In the solution, the mass concentration of the material of the thermosensitive adsorption layer is preferably 1%-20%, for example, 10%. Here, % represents the percentage of the mass of the material of the thermosensitive adsorption layer relative to the mass of the solution.

[0029] The curing process can be, for example, heating. Upon heating, the solvent evaporates, and the material of the temperature-sensitive adsorption layer solidifies to form the temperature-sensitive adsorption layer.

[0030] The curing temperature is preferably 20-80℃, for example 40℃.

[0031] The curing time is preferably 1-72 hours, for example, 24 hours.

[0032] The preparation method of the coating layer can be a conventional preparation method in the art.

[0033] In this invention, preferably, the coating layer is prepared by compression molding, 3D printing technology or CNC machine tool cutting technology.

[0034] The molding temperature is preferably 180-260°C, for example, 200°C.

[0035] The molding time is preferably 10-120s, for example 60s.

[0036] Preferably, the thickness of the temperature-sensitive adsorption layer is less than 100 μm, for example, 60 μm. The molding process allows for a tolerance of ±100 μm in dental model error, and a thickness of less than 100 μm for the temperature-sensitive adsorption layer does not affect the orthodontic performance of the appliance.

[0037] In some specific embodiments of the present invention, the molding process further includes cooling, cutting, and polishing steps.

[0038] In this invention, preferably, at least a portion of the cavity structure is fitted to the corresponding teeth.

[0039] In this invention, the wrapping layer can be a single-layer structure or a multi-layer structure.

[0040] In this invention, preferably, the temperature-sensitive adsorption layer is disposed on the entire surface of the coating layer near the tooth side.

[0041] In this invention, preferably, the material of the coating layer is a polymer material.

[0042] The polymer material is, for example, one or more of polyurethane, polyamide, and copolyester.

[0043] The polyurethane is, for example, thermoplastic polyurethane.

[0044] In this invention, preferably, the thickness ratio of the temperature-sensitive adsorption layer to the coating layer is 1:(5-40), more preferably 1:(5-20), for example 1:7.5, 1:12.5, 1:18.8 or 1:37.5.

[0045] In this invention, the thickness of the temperature-sensitive adsorption layer is preferably 20-100 μm, and more preferably 60-100 μm.

[0046] In this invention, preferably, the thickness of the temperature-sensitive adsorption layer below LCST is less than 200 μm.

[0047] The present invention also discloses the application of the aforementioned orthodontic appliance in orthodontic treatment.

[0048] Based on common knowledge in the field, the above-mentioned preferred conditions can be combined arbitrarily to obtain various preferred embodiments of the present invention.

[0049] The reagents and raw materials used in this invention are all commercially available.

[0050] The positive and progressive effects of this invention are as follows:

[0051] The orthodontic appliance of the present invention can adjust the adhesion force between itself and the teeth according to the changes in the external temperature, which can achieve the advantages of easy peeling at low temperatures and high wearing stability at high temperatures.

[0052] The orthodontic appliance of this invention improves the efficiency of dentists' work, enhances the convenience for patients to remove and wear clear aligners during treatment, and increases removal efficiency after treatment, thus better protecting the patient's teeth. Compared with conventional attachment methods, it reduces the risk of peri-attachment demineralization and caries. Attached Figure Description

[0053] Figure 1 This is a schematic diagram of the orthodontic appliance in Examples 1-3.

[0054] Figure 2 for Figure 1 Cross-sectional view along plane AA.

[0055] The attached figures are labeled as follows:

[0056] 1-Encapsulation layer; 2-Thermosensitive adsorption layer; 3-Cavity. Detailed Implementation

[0057] The present invention is further illustrated below by way of embodiments, but the invention is not limited to the scope of the embodiments described herein. Experimental methods in the following embodiments that do not specify specific conditions were performed according to conventional methods and conditions, or as selected according to the product instructions.

[0058] Examples 1-4

[0059] The temperature-sensitive adsorption layer in Examples 1-4 is made of poly(N-isopropylacrylamide) with a number-average molecular weight of 40,000.

[0060] The wrapping layer is made of thermoplastic polyurethane.

[0061] The method for preparing the orthodontic appliance is as follows:

[0062] The coating layer is prepared by heating the material and then pressing it onto a dental mold. After cooling, it is cut and polished. The heating temperature is 200℃ and the heating time is 60s. The thickness of the coating layer is 0.75mm.

[0063] The method for preparing the temperature-sensitive adsorption layer is as follows: the solution is coated on the entire surface of the coating layer near the tooth side, and after curing, the temperature-sensitive adsorption layer is formed; wherein, the solution includes the material of the temperature-sensitive adsorption layer and water; the mass concentration of the material of the temperature-sensitive adsorption layer in the solution is 10%; wherein, the curing temperature is 40℃ and the time is 24h.

[0064] Example 5

[0065] The temperature-sensitive adsorption layer in Examples 1-4 is a copolymer of poly(N-isopropylacrylamide) and acrylic acid, with a mass ratio of poly(N-isopropylacrylamide) to acrylic acid of 1:0.1 and a number average molecular weight of 30,000.

[0066] The wrapping layer is made of thermoplastic polyurethane.

[0067] The method for preparing the orthodontic appliance is as follows:

[0068] The coating layer is prepared by heating the material and then pressing it onto a dental mold. After cooling, it is cut and polished. The heating temperature is 200℃ and the heating time is 60s. The thickness of the coating layer is 0.75mm.

[0069] The method for preparing the temperature-sensitive adsorption layer is as follows: the solution is coated on the entire surface of the coating layer near the tooth side, and after curing, the temperature-sensitive adsorption layer is formed; wherein, the solution includes the material of the temperature-sensitive adsorption layer and water; the mass concentration of the material of the temperature-sensitive adsorption layer in the solution is 10%; wherein, the curing temperature is 40℃ and the time is 24h.

[0070] The thickness of the temperature-sensitive adsorption layer and the peel strength at 20°C and 37°C for Examples 1-5 are listed in Table 1 below.

[0071] The peel strength test method is 90° peel, referring to ISO 4578:1990.

[0072] The structural schematic diagrams of the orthodontic appliances prepared in Examples 1-5 above are shown below. Figure 1 As shown, the cross-sectional view along plane AA is as follows. Figure 2 As shown, it consists of a shell and a cavity 3. The shell is a temperature-sensitive adsorption layer 2 and a single-layer wrapping layer 1. The cavity 3 formed by the wrapping layer 1 is used to accommodate the tooth. The temperature-sensitive adsorption layer 2 is located on the entire surface of the wrapping layer 1 near the tooth.

[0073] Comparative Example 1

[0074] The orthodontic appliance in Comparative Example 1 does not contain a temperature-sensitive adsorption layer, and all other conditions are the same as in Example 1.

[0075] The thickness of the temperature-sensitive adsorption layer and the peel strength at 20℃ and 37℃ of Comparative Example 1 are listed in Table 1 below.

[0076] Table 1

[0077]

[0078] As shown in the table above, the peel strength of the orthodontic appliance of this embodiment is only below 2N / m at 20℃ and above 39N / m at 37℃. The orthodontic appliance of this embodiment can achieve the advantages of easy peeling at low temperature and high wearing stability at high temperature, which can make it convenient for patients to easily put on and take off during treatment, while improving the work efficiency of doctors.

[0079] As can be seen from the effects of Examples 1-5, a thickness of 60-100μm for the temperature-sensitive adsorption layer can further improve the stability of wearing at high temperatures, and it is also easy to peel off at low temperatures.

[0080] Comparative Example 1 does not use a temperature-sensitive adsorption layer, and its peel strength is 0, resulting in poor wearing stability at both high and low temperatures.

Claims

1. An orthodontic appliance, characterized in that, The orthodontic appliance includes a housing and a cavity. The housing includes a wrapping layer and a temperature-sensitive absorbent layer. The cavity formed by the wrapping layer is used to accommodate teeth. The temperature-sensitive absorbent layer is disposed in at least a portion of the surface of the wrapping layer near the teeth. The material of the temperature-sensitive absorbent layer includes a polymer whose hydrophilicity and hydrophobicity change with temperature.

2. The orthodontic appliance as described in claim 1, characterized in that, The material of the temperature-sensitive adsorption layer includes poly(N-isopropylacrylamide) and / or poly(N-isopropylacrylamide) copolymer; The number average molecular weight of the poly(N-isopropylacrylamide) is 10,000-100,000, for example, 40,000. The number-average molecular weight of the poly(N-isopropylacrylamide) copolymer is 1,000-500,000, for example, 30,000; Preferably, the poly(N-isopropylacrylamide) copolymer is formed by polymerization of poly(N-isopropylacrylamide) and a first monomer; the first monomer includes one or more of acrylic acid, acrylate, and acrylamide. Preferably, the mass ratio of the poly(N-isopropylacrylamide) to the first monomer is 1:(0.01-100).

3. The orthodontic appliance as described in claim 1, characterized in that, The LCST of the material of the temperature-sensitive adsorption layer is 25-45℃; And / or, the peel strength of the temperature-sensitive adsorption layer at 25°C is below 5 N / m; And / or, the peel strength of the temperature-sensitive adsorption layer at 30-37℃ is above 20N / m; And / or, the hydrophilicity / hydrophobicity switching time of the material in the temperature-sensitive adsorption layer is less than 5 minutes.

4. The orthodontic appliance as described in claim 3, characterized in that, The peel strength of the temperature-sensitive adsorption layer at 20°C is below 5 N / m; Preferably, the peel strength of the temperature-sensitive adsorption layer at 20°C is 1-5 N / m; And / or, the peel strength of the temperature-sensitive adsorption layer at 37°C is above 20 N / m; Preferably, the peel strength of the temperature-sensitive adsorption layer at 37°C is 20-1000 N / m.

5. The orthodontic appliance as described in claim 1, characterized in that, The method for preparing the orthodontic appliance includes the following steps: applying a solution to at least a portion of the surface of the wrapping layer near the teeth, and then curing it to form a temperature-sensitive adsorption layer; wherein the solution includes the material and solvent of the temperature-sensitive adsorption layer.

6. The orthodontic appliance as described in claim 5, characterized in that, The coating is applied by brushing, spraying, spin coating, or dip coating. And / or, the solvent is water; And / or, in the solution, the mass concentration of the material of the temperature-sensitive adsorption layer is preferably 1%-20%, for example, 10%; And / or, the curing process is performed by heating; The curing temperature is preferably 20-80°C, for example, 40°C; The curing time is preferably 1-72 hours, for example, 24 hours.

7. The orthodontic appliance as claimed in claim 1, characterized in that, The coating layer is prepared by compression molding, 3D printing technology or CNC machine tool cutting technology.

8. The orthodontic appliance as claimed in claim 1, characterized in that, At least a portion of the cavity structure is fitted with the corresponding teeth; And / or, the wrapping layer is a single-layer structure or a multi-layer structure; And / or, the temperature-sensitive adsorption layer is disposed on the entire surface of the coating layer near the tooth side; And / or, the material of the encapsulation layer is a polymer material.

9. The orthodontic appliance as claimed in claim 1, characterized in that, The thickness ratio of the temperature-sensitive adsorption layer to the coating layer is 1:(5-40), preferably 1:(5-20), for example 1:7.5, 1:12.5, 1:18.8 or 1:37.5; The thickness of the temperature-sensitive adsorption layer is preferably 20-100 μm, and more preferably 60-100 μm. And / or, the thickness of the temperature-sensitive adsorption layer below LCST is less than 200 μm.

10. The use of an orthodontic appliance as described in any one of claims 1-9 in orthodontic treatment.

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