Stress-relief resistant dental orthodontic appliance

Abstract

An orthodontic device formed from a material comprising an interpenetrating polymer network or a semi-interpenetrating polymer network material to prevent or reduce stress relief of the material while the patient uses it. A method of forming an orthodontic device from a material comprising an interpenetrating polymer network or a semi-interpenetrating polymer network material to prevent or reduce stress relief of the material while the patient uses it.

Description

Technology Field

[0001] Cross-reference regarding related applications

[0002] The present application claims the benefit of U.S. provisional application No. 62 / 863,868 filed on June 19, 2019, which is incorporated by reference.

[0003] Technology field

[0004] The subject matter of the present disclosure generally relates to the field of orthodontic devices. More particularly, the present disclosure relates to user-removable orthodontic devices. Background Technology

[0005] The purpose of orthodontics is to move a patient's teeth to a position where function and / or aesthetics are optimized. Traditionally, devices such as braces are applied to the patient's teeth by a dentist, and the set of braces applies continuous force to the teeth, gradually pushing them toward their intended positions. Over time, and through a series of clinical visits and responsive adjustments to the braces by the dentist, the devices move the teeth toward their final destinations.

[0006] More recently, alternatives to conventional orthodontic treatment using traditional attachment devices (e.g., braces) have become available. For example, a system comprising a series of molded plastic aligners has become commercially available from Align Technology, Inc. (San Jose, California, USA) under the trademark Invisalign® System. The Invisalign® System is described in a number of patents and patent applications assigned to Align Technology, Inc., including, for example, U.S. Patent Nos. 6,450,807 and 5,975,893.

[0007] The Invisalign® system typically involves designing and fabricating multiple aligners to be worn by the patient before the aligners are administered to the patient and used to reposition the teeth (e.g., at the start of treatment). Often, designing and planning a customized treatment for the patient utilizes computer-based 3D planning and design tools. The design of the aligners relies on computer modeling of the patient's teeth in a series of planned, consecutive tooth arrangements, and individual aligners are designed to be worn over the teeth, with each aligner applying force to the teeth and elastically repositioning them into each of the planned tooth arrangements.

[0008] Orthodontic devices of the prior art are typically composed of a single (or multiple) non-interpenetrating polymer and undergo stress relief of the material(s). These devices are primarily formed of single-strand thermoplastic polymers, said single-strand thermoplastic polymers having unrestrained polymer chains subjected to stress relief. Consequently, it is typically required to replace the aligners weekly, and the manufacturer must program a slight overshoot into the device to handle stress relief, which is an undesirable quality for the device.

[0009] Embodiments of the present invention relate to dental orthodontic devices, systems, and methods of use as summarized in the following paragraphs. Some embodiments relate to dental orthodontic devices that maximize working elasticity.

[0010] Some embodiments relate to a dental orthodontic device having an interpenetrating polymer network (IPN) material that can be formed from multiple cross-linked polymers.

[0011] Some embodiments relate to a dental orthodontic device having a semi-interpenetrating polymer network (SIPN) material that can be formed from a first cross-linked polymer and a second non-cross-linked polymer.

[0012] In some embodiments, the plasticizing solvent may be configured to leak out of the IPN or SIPN material to gradually reduce the flexibility of the dental orthodontic device after production.

[0013] Some embodiments relate to a method for forming a dental orthodontic device. The method comprises the steps of obtaining a mold of a physical tooth model, thermoforming a material over the mold to form the shape of the dental orthodontic device, and, after forming the shape of the dental orthodontic device, crosslinking a portion of the material to transform the material into a semi-interpenetrating polymer network material.

[0014] Some embodiments relate to a method for forming a dental orthodontic device. The method comprises the steps of obtaining a mold of a physical tooth model and using the mold to thermoform a thermoformable interpenetrating polymer network material to form the dental orthodontic device. Brief explanation of the drawing

[0015] At least for a better understanding of a specific embodiment, reference will be made to the following detailed description, which should be read together with the attached drawings. 도 1 This is a perspective view of a jaw and a dental orthodontic device according to some embodiments. 도 2 is a perspective view of a process for forming a dental orthodontic device according to some embodiments. The drawings illustrate various embodiments of the invention for illustrative purposes only, wherein similar reference numbers are used to identify similar elements. A person skilled in the art will readily recognize from the following discussion that alternative embodiments of the structures and methods illustrated in the drawings may be utilized without departing from the principles of the invention as described herein. Specific details for implementing the invention

[0016] An embodiment is disclosed relating to a dental orthodontic device composed of an interpenetrating polymer network (IPN) or a semi-interpenetrating polymer network (SIPN) formed of multiple polymers. The use of such materials can resolve the stress relief problems experienced by thermoforming materials due to having a non-crosslinked structure. Possible advantages include reducing the number of dental orthodontic devices used in a treatment series and providing a more accurate orthodontic device that can reach the final treatment goal as intended without requiring overshoot in design parameters.

[0017] Before the present invention is described in more detail, it should be understood that the invention is not limited to the specific embodiments described and, of course, may be modified. Furthermore, it should be understood that the terms used herein are for the purpose of describing specific embodiments only, and that the scope of the invention is not intended to be limited, as it will be limited only by the appended claims.

[0018] Where a range of values ​​is provided, each intermediate value between the upper and lower limits of such range (up to 1 / 10 of the unit of the lower limit, unless the context clearly indicates otherwise) and any other mentioned or intermediate value within the aforementioned range are understood to be included within the scope of the present invention. The upper and lower limits of such smaller ranges may be independently included within the smaller ranges and are also included within the present invention subject to any specifically excluded limits from the mentioned ranges. Where the mentioned range includes one or both of the limits, the range excluding one or both of the included limits is also included in the present invention.

[0019] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this invention pertains. Any method and material similar or equivalent to that described herein may also be used to practice or test the invention, but representative exemplary methods and materials are described hereafter.

[0020] It is noted that, as used in the present and attached claims, the singular form and "above" include multiple referents unless the context clearly indicates otherwise. It is also noted that the claims may be drafted to exclude any optional elements. Accordingly, such references are intended to serve as a precedent for the use of such exclusive terms, such as "alone" or "only," in relation to the reference of claim elements or the use of "negative" limitations.

[0021] As will be apparent to those skilled in the art upon reading this disclosure, each of the individual embodiments described and illustrated herein has individual components and features that can be easily separated from or combined with the features of any of the other embodiments without departing from the scope or spirit of the invention. Any mentioned method may be performed in the order of the mentioned events or in any other logically possible order.

[0022] FIG. 1 provides a suitable starting point for a detailed description of various embodiments of the present invention regarding a tooth repositioning device designed to apply a repositioning force to teeth. The dental orthodontic device (10) may be worn by a patient to achieve the gradual repositioning of individual teeth in the jaw (12). The dental orthodontic device (10) may comprise a shell having a tooth-receiving cavity that accommodates and elastically repositions the teeth. In some embodiments, the polymer device may be formed from a sheet of a suitable layer of polymer material. The device may be fitted over or less than all teeth present in the upper or lower jaw.

[0023] In some embodiments, only specific teeth accommodated by the device will be repositioned by the device, while other teeth may provide a base or anchor area to hold the device in place when the device applies force to the teeth or teeth to be repositioned. In some cases, at some point during treatment, a number, most, or even all of the teeth will be repositioned. The repositioned teeth may also serve as a base or anchor to hold the device when the patient wears it. Typically, no wire or other means will be provided to hold the device in place on the teeth. However, in some cases, it may be desirable or necessary to provide individual anchors on the teeth, with the device having a corresponding receptacle or aperture to allow the device to apply selected force to the teeth. Basic methods for determining an orthodontic treatment plan using a series of incremented appliances, as well as guidelines for forming orthodontic appliances, are described in U.S. Patent Nos. 6,450,807 and 5,975,893, which are incorporated herein by reference, but only to the extent that the said patents do not contradict the newer teachings disclosed herein.

[0024] The device may be designed and / or provided as part of a set of multiple devices. In one such embodiment, each device may be configured such that the tooth-accepting cavity has a geometry corresponding to an intermediate or final tooth arrangement intended for the device. By placing a series of incremental position adjustment appliances over the patient's teeth, the patient's teeth may be progressively repositioned from an initial tooth arrangement to a target tooth arrangement. The target tooth arrangement may be a planned final tooth arrangement selected for the patient's teeth at the end of all planned orthodontic treatment. Alternatively, the target arrangement may be one of a number of intermediate arrangements for the patient's teeth during the course of orthodontic treatment. Accordingly, it is understood that the target tooth arrangement may be any planned resulting arrangement for the patient's teeth following one or more incremental repositioning stages. Likewise, the initial tooth arrangement may be any initial arrangement for the patient's teeth, followed by one or more incremental repositioning stages.

[0025] Orthodontic appliances may be produced in the same stage, as a set, or in a batch, for example, at the beginning of a treatment stage, and the patient wears each appliance until the pressure of each appliance on the teeth is no longer felt or until the maximum amount of tooth movement expressed for the given stage is achieved. Multiple different appliances (e.g., a set) may be designed and even manufactured before the patient wears any of the appliances. After wearing the appliances for an appropriate period, the patient replaces the current appliance with a subsequent appliance in the series until the appliance is no longer retained. Orthodontic appliances are generally not attached to the teeth, and the patient can place and replace the appliances at any time during the procedure (e.g., patient-removable appliance).

[0026] A final orthodontic appliance or multiple appliances in a series may have a geometry or geometry selected to overcorrect the tooth alignment; that is, they may have a geometry that moves individual teeth beyond the tooth alignment selected as "final" (if fully achieved). Such overcorrection may be desirable to offset the allowance of potential relapse after the repositioning method is completed, namely, individual teeth moving back toward their pre-orthodontic positions. Overcorrection can also be beneficial for accelerating the pace of orthodontics, meaning that by using appliances with geometry positioned beyond the intended intermediate or final positions, individual teeth will move toward those positions at a greater speed. In such cases, the use of the appliance may be terminated before the teeth reach the positions prescribed by the appliance.

[0027] The device may have a thickness in the range of 0.001 to 0.030 inches and may be composed of polyester, copolyester, polycarbonate, thermoplastic polyurethane, polypropylene, polyethylene, polypropylene and polyethylene copolymer, acrylic, cyclic block copolymer, polyetheretherketone, polyamide, polyethylene terephthalate, polybutylene terephthalate, polyetherimide, polyethersulfone, polytrimethylene terephthalate, or a combination thereof.

[0028] To address the issue of stress relief, orthodontic aligners may be formed from materials having an interpenetrating polymer network (IPN) or a semi-interpenetrating polymer network (SIPN) formed from multiple polymers. Detailed information and methods for forming IPN and SIPN are described in the literature [Klempner et al., Interpenetrating Polymer Networks Advances in Chemistry ; American Chemical Society: Washington, DC, 1994, Roland; Interpenetrating Polymer Networks (IPN): Structure and Mechanical Behavior [Encyclopedia of Polymeric Nanomaterials, 2013], US8883915B2 and US6720402B2 (these are incorporated by reference). Briefly, an IPN is a network of two or more inseparable polymers that are at least partially interlaced (chemically or physically). SIPNs are similarly structured, but one of the polymers has a linear structure and can be separated from the network, for example, by the use of a solvent.

[0029] Orthodontic devices of the prior art are typically composed of a single (or multiple non-interpenetrating polymer) material(s) and undergo stress relief. These devices are primarily formed from single-strand thermoplastic polymers, which have unbound polymer chains subjected to stress relief. Consequently, it is typically required to replace the device weekly, and the manufacturer must program a slight overshoot into the device to handle the stress relief. Often, the device cannot reach its final intended position due to stress relief.

[0030] Orthodontic devices formed from IPN and SIPN are much more resistant to stress relief because the interpenetrating polymers are restrained. Therefore, not only are the major modes of failure found in thermoplastic materials avoided, but the need to crosslink all or part of the non-interpenetrating polymer, which can lead to brittleness and loss of elasticity, is also avoided. Depending on the formulation, IPN and SIPN can also provide the benefits of heterogeneous polymer physical properties, such as elasticity and transparency.

[0031] In some embodiments, orthodontic devices formed from IPN and SIPN may also be modified using solvent plasticizers, such as biocompatible solvents (e.g., limonene, eugenol). These solvents are described in the literature [Nakamura et al., Nontoxic organic solvents identified using an a priori approach with Hansen solubility parameters This is described in [, Chem. Commun., 2017, 53, 4096-4099] (incorporated by reference). The inclusion of a solvent may provide initial flexibility that helps alleviate patient discomfort. The device may be configured to leak the solvent slowly (e.g., over 1 to 3 days), which allows the device to gradually intensify rather than provide sudden and potentially painful treatment, and enables the patient to easily adapt to the treatment protocol.

[0032] FIG. 2 illustrates an example of a basic process (30) for forming a dental orthodontic device. As illustrated, a thermoformable IPN or SIPN material (32) can be formed into a dental orthodontic device (36). The material (32) may be a single layer to form a single shell or multiple non-bonded layers of material to form multiple shells at once. In this exemplary process, the dental orthodontic device (36) may be manufactured using a physical tooth model or mold (34). The dental orthodontic device (36) may be manufactured by heating the thermoformable material (32) and then forming the material over the teeth in the physical tooth model (34) by vacuum or pressure. The dental orthodontic device (36) is a direct representation of the physical tooth model.

[0033] Some IPNs are thermoformable and can be used in conjunction with the methods mentioned above. Thermoplastic IPN materials are hybrids between polymer blends and IPNs that involve physical rather than chemical crosslinking. These materials flow at elevated temperatures like thermoplastic materials and crosslink at the operating temperature to behave like IPNs. Types of crosslinking include block copolymer morphology, ionic groups, and semi-crystallinity.

[0034] Multiple IPNs, for example, IPNs formed sequentially or simultaneously, are thermosetting materials that cannot be molded after formation. In the case of such materials, the base monomer and crosslinking agent constituting the IPN may be required to be injection molded.

[0035] SIPN can be formed from an established thermoforming-based method, wherein the material (32) comprises a thermoforming polymer used to form the shape of a dental orthodontic device (36). The thermoforming polymer is in the form of strands, and the material (32) also comprises a non-crosslinked monomer. After the thermoforming step, the monomer can be crosslinked (e.g. by UV and / or heat) to form a semi-interpenetrating polymer structure together with the strand-form polymer.

[0036] A monomer or monomer formulation may be mixed with an initiator activated by UV, heat, or both. A solvent compatible with the polymer and miscible with the monomer formulation may transport the monomer into the matrix to form an interpenetrating network. It may be necessary to wash or extract unreacted monomer from the finished aligner. In some embodiments, a silicon prepolymer with a platinum catalyst and an acrylate-modified silicon monomer may be used without this extraction step.

[0037] One or a series of physical tooth models, such as the model described above, can be used to create elastic repositioning devices for orthodontic treatment. Similar to the process described above, each device can be created by thermoforming a multilayer polymer material onto a mold of the desired tooth arrangement to form a dental device. The tooth positioning device of the desired tooth arrangement generally matches the patient's teeth but is slightly misaligned with the initial tooth configuration. Placing an elastic positioner over the teeth applies a controlled force at specific locations to progressively move the teeth to the desired configuration. Repeating this process with a succession of devices containing new configurations eventually moves the teeth through a series of intermediate configurations to the desired final configuration.

[0038] Throughout the foregoing description, and for the purposes of explanation, numerous specific details are presented to provide a complete understanding of the described technology. However, it will be apparent to those skilled in the art that these technologies can be practiced without some of these specific details. Although various embodiments incorporating these teachings have been shown and described in detail, those skilled in the art can readily devise numerous other modified embodiments or mechanisms to incorporate these technologies. Furthermore, embodiments may include various operations, fewer operations, or more operations as presented above; or operations in a predetermined order. Accordingly, the scope and spirit of the invention must be determined with respect to the following claims as well as their legal equivalents.

Claims

Claim 1 An orthodontic appliance comprising: a shell shaped to accommodate and reposition teeth, wherein the shell comprises: an interpenetrating polymer network (IPN) material formed of a multi-crosslinked polymer to provide target flexibility for a treatment protocol and resistance to stress relief of the shell, and a plasticizing solvent, wherein the plasticizing solvent provides the shell with initial flexibility greater than the target flexibility of the shell for the treatment protocol, and subsequently leaks out of the IPN material over 1 to 3 days when inserted into the oral cavity of a patient receiving treatment according to the treatment protocol, thereby progressively strengthening the shell of the orthodontic appliance over 1 to 3 days and progressively reducing the flexibility of the shell to reach the target flexibility for the treatment protocol, so that the patient can easily adapt to the treatment protocol over 1 to 3 days. Claim 2 An orthodontic device comprising: a shell shaped to accommodate and reposition teeth, wherein the shell comprises: a semi-interpenetrating polymer network (SIPN) material formed of a first cross-linked polymer and a second non-cross-linked polymer to provide target flexibility for a treatment protocol and resistance to stress relief of the shell, and a plasticizing solvent, wherein the plasticizing solvent provides the shell with initial flexibility greater than the target flexibility of the shell for the treatment protocol, and subsequently leaks out of the SIPN material over 1 to 3 days when inserted into the oral cavity of a patient receiving treatment according to the treatment protocol, thereby progressively strengthening the shell of the orthodontic device over 1 to 3 days and progressively reducing the flexibility of the shell to reach the target flexibility for the treatment protocol, so as to enable the patient to easily adapt to the treatment protocol over 1 to 3 days. Claim 3 A method for forming a dental orthodontic device, wherein the dental orthodontic device comprises a shell shaped to accommodate and reposition teeth, the shell comprises i) a semi-interpenetrating polymer network (SIPN) material formed of a first cross-linked polymer and a second non-cross-linked polymer to provide target flexibility for a treatment protocol and resistance to stress relief of the shell, and ii) a plasticizing solvent, wherein the plasticizing solvent provides the shell with initial flexibility greater than the target flexibility of the shell for the treatment protocol, and subsequently leaks out of the SIPN material over 1 to 3 days when inserted into the oral cavity of a patient receiving treatment according to the treatment protocol, thereby progressively strengthening the shell of the dental orthodontic device over the 1 to 3 days and progressively reducing the flexibility of the shell to reach the target flexibility for the treatment protocol, so that the patient can easily adapt to the treatment protocol over the 1 to 3 days, and the method comprises: a step of obtaining a mold of a physical tooth model; and a step of thermoforming a material on a mold to form the shape of the dental orthodontic device, wherein the material comprises a strand-form thermoformable polymer and a non-crosslinked monomer; and, after forming the shape of the shell of the dental orthodontic device, applying UV or heat to crosslink the non-crosslinked monomer to form a SIPN structure together with the strand-form thermoformable polymer, thereby transforming the material into the SIPN material to provide the target flexibility of the shell for the treatment protocol and resistance to stress relief for the shell;A method comprising the step of configuring the shell of the orthodontic device such that the shell of the orthodontic device is modified with a plasticizing solvent to provide the shell with an initial flexibility greater than the target flexibility of the shell for the treatment protocol, and subsequently leaks out of the SIPN material over 1 to 3 days when inserted into the oral cavity of a patient receiving treatment according to the treatment protocol, thereby progressively strengthening the shell of the orthodontic device and progressively reducing the flexibility of the shell over 1 to 3 days to reach the target flexibility for the treatment protocol, so that the patient can easily adapt to the treatment protocol over 1 to 3 days. Claim 4 A method for forming a dental orthodontic device, wherein the dental orthodontic device comprises a shell shaped to accommodate and reposition teeth, wherein the shell comprises i) an interpenetrating polymer network (IPN) material formed of a multi-crosslinked polymer to provide target flexibility for a treatment protocol and resistance to stress relief of the shell, and ii) a plasticizing solvent, wherein the plasticizing solvent provides the shell with initial flexibility greater than the target flexibility of the shell for the treatment protocol, and subsequently leaks out of the IPN material over 1 to 3 days when inserted into the oral cavity of a patient receiving treatment according to the treatment protocol, thereby progressively strengthening the shell of the dental orthodontic device over the 1 to 3 days and progressively reducing the flexibility of the shell to reach the target flexibility for the treatment protocol, so as to enable the patient to easily adapt to the treatment protocol over the 1 to 3 days, and the method comprises: a step of obtaining a mold of a physical tooth model; A method comprising: a step of thermoforming a thermoformable interpenetrating polymer network (IPN) material using the mold to form the orthodontic device and providing the shell with a target flexibility and resistance to stress relief for the treatment protocol; and a step of deforming the shell of the orthodontic device with the plasticizing solvent to provide the shell with an initial flexibility greater than the target flexibility of the shell for the treatment protocol, and subsequently leaking out of the IPN material over 1 to 3 days when inserted into the oral cavity of a patient receiving treatment according to the treatment protocol, thereby progressively strengthening the shell of the orthodontic device over 1 to 3 days and progressively reducing the flexibility of the shell to reach the target flexibility for the treatment protocol, so that the patient can easily adapt to the treatment protocol over 1 to 3 days. Claim 5 delete Claim 6 A dental orthodontic device according to claim 1, wherein the plasticizing solvent is a biocompatible solvent. Claim 7 delete Claim 8 delete Claim 9 A dental orthodontic device according to paragraph 2, wherein the plasticizing solvent is a biocompatible solvent. Claim 10 delete

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