Elastic orthodontic appliances, systems, and methods of use

Abstract

To provide a user with a removable orthodontic appliance. The orthodontic appliance (10) is comprised of shells (14, 16, 18) shaped to receive teeth. The shells are constructed from one or more polymeric materials, stacked, and can be attached to one another in various ways, including being attached only around the edges of each shell. The orthodontic appliance can be one of a series of similar appliances for the progressive orthodontic correction of teeth.

Description

[Technical Field]

[0001] REFERENCE TO RELATED APPLICATIONS This application claims the benefit of U.S. Provisional Application No. 62 / 797,797, filed January 28, 2019, which is incorporated herein by reference.

[0002] FIELD OF THE INVENTION The subject matter of this disclosure relates generally to the field of orthodontic appliances. More particularly, this disclosure relates to user-removable orthodontic appliances. [Background technology]

[0003] The goal of orthodontics is to move a patient's teeth to positions that optimize function and / or aesthetics. Traditionally, appliances such as orthodontic braces are applied to the patient's teeth by the treating practitioner, with a set of braces exerting continuous force on the teeth and gradually urging the teeth toward the intended position. Over time, and with a series of clinical visits and adjustments to the appliances by the practitioner to accommodate changing conditions, the appliances move the teeth toward their final destination.

[0004] Recently, alternatives to traditional orthodontic treatment using traditional fixed orthodontic appliances (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. of San Jose, California, under the trade name Invisalign™ System. The Invisalign™ System is described in numerous patents and patent applications assigned to Align Technology, Inc., including U.S. Patent No. 6,450,807 and U.S. Patent No. 5,975,893.

[0005] The Invisalign™ system typically involves designing and fabricating multiple aligners for the patient to wear before administering them and using them to reposition the teeth (e.g., at the beginning of treatment). Often, developing and planning a patient's personalized treatment involves the use of computer-assisted three-dimensional design tools. Aligner design relies on computer modeling of the patient's teeth in a series of planned sequential tooth positions, and individual aligners are designed to be worn over the teeth so that each aligner applies force to the teeth and elastically repositions the teeth into each of the planned tooth positions.

[0006] Naturally, such aligners are less noticeable than traditional braces because they are typically made from a transparent material; however, many people believe that the aligners are easily noticeable due to the glossy sheen of the transparent material. Like traditional braces, aligners must be worn nearly constantly (20-22 hours per day), with breaks allowed for eating and cleaning. Only minor breaks are permitted, and aligners do not have sufficient malleability to account for tooth misalignment, which is based on the aligner's physical and material properties. Increasing the operating tolerance to account for higher misalignment requires increasing the aligner's working elasticity; that is, the aligner can stretch to fit the teeth without causing permanent deformation. However, highly elastic aligners typically would not provide sufficient force to move the teeth required for orthodontic treatment. Problems such as these can ultimately contribute to failure and the need to restart treatment because of failure to wear aligners according to prescribed requirements. Summary of the Invention

[0007] Embodiments of the present invention relate to orthodontic appliances, systems, and methods of use as summarized in the following paragraphs: Some embodiments relate to orthodontic appliances that maximize working elasticity.

[0008] Some embodiments relate to orthodontic appliances that can have shells shaped to receive teeth, where the shells can be stacked and are not substantially attached to one another.

[0009] Some embodiments relate to orthodontic appliances that can have shells shaped to receive teeth, which can be stacked and affixed to one another in various ways.

[0010] Some embodiments relate to orthodontic appliances and can have multiple shells that are substantially unattached to maximize working resiliency and are shaped to receive teeth that are mechanically engaged to provide rigidity for applying force to reposition the teeth.

[0011] Some embodiments relate to orthodontic appliances that can have a stack of mechanically interlocked shells. The stack of mechanically interlocked shells can have a hardness substantially equivalent to that of a single shell of the same thickness as the stack. The stack of mechanically interlocked shells can have the ability to be at least partially mechanically disengaged to increase working resiliency.

[0012] Some embodiments relate to orthodontic appliances that can have a first shell with several cavities shaped to receive teeth. The orthodontic appliance can include a second shell that can be shaped to receive the first shell. The second shell can be stacked on top of the first shell. The first shell and the second shell can be mechanically interlocked with each other between their surfaces, but are not substantially affixed to each other.

[0013] In some embodiments, the second shell and the first shell can be affixed to one another at discrete attachment locations on the first and second shells.

[0014] In some embodiments, the first shell can have a bottom first surface for direct engagement with a tooth and a top first surface opposite the bottom first surface. The second shell can have a bottom second surface for mechanically engaging the top first surface of the first shell and a top second surface opposite the bottom second surface. The top first surface and bottom second surface are not significantly attached to each other.

[0015] In some embodiments, the fixed, discrete attachment locations comprise between 1 and less than 80% of the combined surface area of ​​the upper first and lower second surfaces.

[0016] In some embodiments, the first shell has a first edge between an upper first surface and a lower first surface, and the second shell has a second edge between an upper second surface and a lower second surface, and the discrete attachment locations are located about the first and second edges.

[0017] In some embodiments, the shells can be made of the same material.

[0018] In some embodiments, a relatively high elastic shell can be provided between the shells.

[0019] In some embodiments, the shells can include a first shell that can have a cavity shaped to receive a tooth, and at least one additional shell that can be shaped to receive the first shell, where the at least one additional shell can be stacked over the first shell.

[0020] In some embodiments, the first shell and the at least one additional shell can be attached to one another at spaced attachment locations of the first shell and the at least one additional shell.

[0021] In some embodiments, the first shell can have a bottom first surface for direct engagement with a tooth and a top first surface opposite the bottom first surface. At least one additional shell can have a bottom second surface for mechanically engaging the top first surface of the first shell and a top second surface opposite the bottom second surface. The top first surface and bottom second surface can be positioned such that they are not significantly (significantly) attached to each other.

[0022] In some embodiments, the first shell can have a first edge between a first upper surface and a first lower surface, and at least one additional shell can have a second edge between a second upper surface and a second lower surface, and discrete attachment locations can be located about the first edge and the second edge.

[0023] In some embodiments, the first shell can have a bottom first surface for directly engaging a tooth, a top first surface opposite the bottom first surface, and a first edge defined therebetween. At least one additional shell can have a bottom second surface for mechanically engaging the top first surface of the first shell, a top second surface opposite the bottom second surface, and a second edge defined therebetween. Some or all of the first and second edges can be positioned so that they do not contact each other.

[0024] In some embodiments, the at least one additional shell can be a second shell, which can include a third shell.

[0025] In some embodiments, the shells may consist of only a first shell, a second shell, and a third shell.

[0026] In some embodiments, the second edge can be attached to the upper first surface or the lower first surface.

[0027] In some embodiments, the first edge can be attached to the lower second surface or the upper second surface.

[0028] In some embodiments, the first edge and the second edge can be spaced apart by 0.2 to 2.0 mm.

[0029] In some embodiments, the at least one additional shell can be a second shell, which can include a third shell, which can include a bottom second surface for mechanically engaging a top second surface of the second shell, a top third surface opposite the bottom third surface, and a third edge defined therebetween, and some or all of the first edge, second edge, and third edge can be positioned so as not to contact one another.

[0030] In some embodiments, the first edge, second edge, and third edge can be spaced apart by 0.2 to 3.0 mm.

[0031] In some embodiments, all of the shells can be constructed from the same type of material.

[0032] In some embodiments, variously attached can mean having attachment locations that can be less than 1-80% of the total area of ​​the shell.

[0033] In some embodiments, variously attached can mean having attachment locations that can be less than 1-60% of the total area of ​​the shell.

[0034] In some embodiments, variously attached can mean having attachment locations that can be less than 1-40% of the total area of ​​the shell.

[0035] In some embodiments, variously attached can mean having attachment locations that can be less than 1-20% of the total area of ​​the shell.

[0036] Some embodiments relate to a system for repositioning teeth from an initial tooth arrangement to a final tooth arrangement. The system can include a plurality of orthodontic appliances configured to receive and reposition the teeth. The plurality of orthodontic appliances can include at least one aspect of the orthodontic appliance described herein.

[0037] Some embodiments relate to a method for repositioning teeth from an initial tooth arrangement to a final tooth arrangement, which may include progressive use of the system.

[0038] In some embodiments, at least one orthodontic appliance of the system can be used for less than 12 hours per day. [Brief explanation of the drawings]

[0039] For a better understanding of at least certain embodiments, reference is made to the following detailed description, which should be read in conjunction with the accompanying drawings.

[0040] [Figure 1] FIG. 1 is a perspective view of a jaw and an orthodontic appliance, according to some embodiments. [Figure 2] FIG. 2 is an exploded view of an orthodontic appliance, according to some embodiments. [Figure 3A] FIG. 3A is a connection schematic for an orthodontic appliance, according to some embodiments. [Figure 3B] FIG. 3B is a detailed view of a connection schematic for an orthodontic appliance, according to some embodiments. [Figure 4] FIG. 4 is a perspective view of a process for molding an orthodontic appliance, according to some embodiments. DETAILED DESCRIPTION OF THE INVENTION

[0041] The drawings depict various embodiments of the present invention for illustrative purposes only, wherein the drawings use like reference numerals to identify like elements. Those skilled in the art will readily recognize from the following description that alternative embodiments of the structures and methods illustrated in the drawings may be used without departing from the principles of the present invention as described herein.

[0042] Embodiments are disclosed that relate to orthodontic appliances constructed from multiple shells for the purpose of maximizing working resilience, defined as the ability of an orthodontic appliance to elastically deform to accommodate initial tooth positions. This flexibility allows the orthodontic appliance to achieve a greater range of initial tooth placement (i.e., flexion) positions that differ from the appliance's target tooth placement (i.e., rest) position. Potential advantages include greater rest periods (e.g., 8-12 hours) between required wear periods and greater discretion regarding patient non-compliance with required wear times, thus increasing efficacy.

[0043] Before the present invention is described in more detail, it is to be understood that the invention is not limited to the particular embodiments described, as such may, of course, vary. Moreover, the scope of the present invention will be limited only by the appended claims, and the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting.

[0044] When a range of values ​​is provided, it is understood that each intermediate value, to the tenth of the unit of the lower limit, between the upper and lower limits of that range and any other stated range, or each intermediate value within that stated range, is encompassed within the scope of the invention, unless the context clearly dictates otherwise. The upper and lower limits of these smaller ranges may independently be included in the smaller ranges and are also encompassed within the scope of the invention, subject to any specifically excluded limit in the stated range. Where the stated range includes one or both of those limits, ranges excluding either or both of those included limits are also encompassed within the invention.

[0045] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although any materials and methods similar or equivalent to those described herein can also be used in the practice or testing of the present invention, representative exemplary methods and materials are now described herein.

[0046] Please note that, as used in the specification and the appended claims, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. Furthermore, please note that the claims may be drafted to exclude any optional element. As such, this statement is intended to serve as a predicate for the use of exclusive terminology such as "solely," "only," and the like, in connection with the use of "negative" limitations or recitation of claim elements.

[0047] As will be apparent to one skilled in the art upon reading this disclosure, each of the individual embodiments described and illustrated herein has distinct components and features that can be readily separated from or combined with the features of several other embodiments without departing from the scope or spirit of the invention. Any recited method can be carried out in the order of events recited or in any other order that is logically possible.

[0048] FIG. 1 relates to a tooth repositioning device designed to apply a repositioning force to teeth and provides a suitable starting point for the detailed description of various embodiments of the present invention. An orthodontic device 10 can be worn by a patient to achieve gradual repositioning of individual teeth within a jaw 12. The orthodontic device 10 can include a shell having a cavity for receiving and resiliently repositioning the teeth. In some embodiments, the polymeric device can be formed from a sheet of appropriate layers of polymeric material. The device can be worn over all or fewer than all of the teeth in the upper or lower jaw.

[0049] In some embodiments, only the specific teeth accepted by the appliance will be repositioned by the appliance, while other teeth can provide base or anchor areas to hold the appliance in place as the specific teeth apply force against the tooth or teeth targeted for repositioning. In some cases, many, most, or even all teeth will be repositioned (repositioned) at some point during treatment. The moved teeth can also serve as bases or anchors to hold the appliance when the patient wears it. Generally, no wires or other means are provided to hold the appliance over the teeth. However, in some cases, it may be desirable or necessary to provide corresponding receptacles or apertures in the appliance for individual anchors on the teeth so that the appliance can apply selected forces to the teeth. Basic methods for specifying an orthodontic treatment plan using a series of progressive appliances, as well as instructions for molding the appliances, are described in the following U.S. patents: U.S. Pat. No. 6,450,807; and U.S. Pat. No. 5,975,893. Those patents are incorporated herein by reference only to the extent that they do not contradict the more recent teachings disclosed herein.

[0050] An appliance can be designed and / or provided as part of a set of multiple appliances. In such embodiments, each appliance may be configured so that the tooth-receiving cavities have a geometry corresponding to the intermediate or final tooth arrangement intended for that appliance. The patient's teeth can be steadily repositioned from their initial tooth arrangement to their target tooth arrangement by attaching a series of incremental position-adjusting appliances to the patient's teeth. The target tooth arrangement can be the planned final tooth arrangement selected for the patient's teeth at the end of all planned orthodontic treatment. Alternatively, the target arrangement can be one of many intermediate arrangements for the patient's teeth during the course of orthodontic treatment. As such, it is understood that the target tooth arrangement can be any resulting planned arrangement for the patient's teeth following one or more incremental repositioning steps. Similarly, the initial tooth arrangement can be any initial arrangement for the patient's teeth followed by one or more incremental repositioning steps.

[0051] Orthodontic appliances can be all produced in the same phase, or in sets or batches, for example, at the beginning of a phase of treatment, and the patient wears each appliance until the pressure of each appliance can no longer be felt on the teeth or the maximum amount of manifested tooth movement for that given phase has occurred. A number of different appliances (e.g., a set) can even be designed and manufactured before the patient wears any of the appliances. After wearing an appliance for an appropriate period of time, the patient replaces (changes) the current appliance with the next appliance in the series until no appliances remain. Orthodontic appliances are generally not affixed to the teeth, and the patient can wear and change appliances (e.g., patient-removable appliances) at any time during treatment.

[0052] The final orthodontic appliance, or some appliances in the series, may have one or more geometries selected to overcorrect tooth positioning, i.e., they may have geometries that would (if fully achieved) move individual teeth beyond the tooth position selected as "final." Such overcorrection may be desirable to offset potential relapse after the repositioning procedure is terminated, i.e., to allow individual teeth to move back to their pre-corrected positions. Overcorrection may also be beneficial to accelerate correction speed, i.e., by having appliances with geometries positioned beyond the desired intermediate or final positions, individual teeth will be displaced into position at a greater rate. In such cases, use of the appliance may be terminated before the teeth reach the positions prescribed by the appliance.

[0053] FIG. 2 shows an exploded view of one example of an orthodontic appliance 10. The orthodontic appliance 10 can include a first shell 14 having a tooth-engaging surface and an opposing upper surface. The orthodontic appliance 10 can also include a second shell 16 having a lower shell-engaging surface and an opposing upper surface exposed to the mouth. Optionally, one or more additional shells 18 can be positioned between the first shell 14 and the second shell 16. In some embodiments, the more shells used, the greater the working resilience of the orthodontic appliance 10, assuming the same material is used for each shell.

[0054] While the orthodontic device 10 is shown in an exploded view for better understanding, it is intended that the shells of the orthodontic device 10 be mechanically engaged with one another within the stack. "Mechanically engaged" is defined herein as a substantially non-attached or variably attached engagement between one or more shells to approximate the strength of a single shell device of approximately the same thickness as the stacked shells. The mechanical engagement can be achieved by stacking the shells, with the mating surface of the lower shell of the second shell largely fitting against the upper surface of the first shell. In some embodiments, the shells can be loosely stacked, i.e., without the shells in the inverted stack self-disassembling or creating a compression or interference fit between the shells before being substantially attached or variably attached. The shells are substantially non-attached (or variably attached) because a significant amount of the surface area between the shells is not bonded or is otherwise rendered inseparable through some process, and the remaining surfaces are affixed. In some embodiments, the substantially unattached or variously affixed shells have less than 1-2%, 1-5%, 1-10%, 1-20%, 1-40%, 1-60%, or 1-80% of the combined contact surface of the affixed shells. The unattached area can be limited depending on the needs of the device; thus, in some embodiments, most of the surface area of ​​the device is affixed while the remaining portion is unaffixed, because only the latter requires high working resilience.

[0055] In some embodiments, the lack of substantial interlocking between the shells provides greater working resilience to the orthodontic device 10 because the tooth-engaging shells are thinner and therefore more flexible, allowing the outer shells to flex in multiple directions away from the tooth-engaging shells. In some embodiments, this may result in partial mechanical separation between some of the engaging surfaces of the shells; however, this separation is not sufficient to significantly impair the flexural modulus of the device necessary to align the teeth to their target positions.

[0056] FIG. 3A shows a schematic diagram for bonding the shells of the orthodontic appliance 10 to different locations. Each enclosed "X" represents a potential anchor point between the shells. Alternatively, as indicated by the dashed lines, the edges of each shell can serve as continuous or discontinuous anchoring areas. Generally, the more anchorage provided, the weaker the working resilience of the appliance 10 will be. The anchor points can be identified based on which teeth are moving, which teeth are acting as anchors, and the amount of working resilience required. Alternatively, the shells can be uniformly and weakly bonded with a highly resilient material with low bond strength, allowing for a large amount of stretch and / or shear. Such embodiments can be substantially non-bonded or variably bonded, since the working flexibility of such appliances is maintained due to the weak bond characteristics.

[0057] In some embodiments, the shells of the orthodontic device 10 may not be identical, such as one shell having a larger or smaller surface area than another. Accordingly, in some embodiments, edges are defined by the upper and lower surfaces of each shell, and the edges of such shells may be separated by a gap (e.g., 0.20-3.0 mm), as depicted in FIG. 3B, which shows an example with three shells 14, 16, and 18 and three edges 14a, 16a, and 18a. In some embodiments, referring to the arrangement shown in FIG. 2, the bottom shell 14 may have the largest surface area, such that edge 14a is in the bottom position as shown, and shells 18 and 16, respectively, have smaller surface areas, with edge 16a in the top position. In such embodiments, the shells 14, 16, and 18 are stacked such that the step formed by edges 14a, 16a, and 18a faces outward, away from the teeth. 2, the top shell 16 can have the largest surface area, such that edge 16a is in the bottom position shown, and shells 18 and 14 each have a smaller surface area such that edge 14a is in the top position. In such embodiments, shells 14, 16, 18 are stacked such that the step formed by edges 14a, 16a, 18a faces inward, i.e., toward the teeth.

[0058] Providing such a gap or gaps can be used to adjust the bending elasticity of the orthodontic device 10 and can result in less tongue irritation to the patient that could occur due to the thickness of the material to which the edges are bonded in the same location. To mitigate irritation, the gaps can be located in the mouth-facing area, resulting in a stepped edge (e.g., edges 14a, 16a, 18a) facing the tongue, or the tooth-engaging shell can have a smaller surface area than the shells stacked on it, resulting in an internal, tooth-facing step and a single tongue-contactable shell edge (e.g., edge 16a). In some embodiments, the shell engaging the lowermost tooth can have a larger or smaller total surface area than the second shell stacked on it, resulting in at least a portion of the second shell's edge being separated from the tooth-engaging shell's edge. In some embodiments, only a portion of the mouth-facing edge has such a gap, while in other embodiments, a uniform or non-uniform gap can exist between all of the edges. In some embodiments, the orthodontic appliance 10 can include multiple shells, each having a different surface area.

[0059] The shell can have a thickness ranging from 0.001 to 0.015 inches thick and can be constructed from 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 combinations thereof. In some embodiments, the shell is coated with a lubricious material or provided with a surface treatment to reduce friction between the shells. In some embodiments, the interior portion of the shell is treated with a hydrophobic coating to prevent liquids from penetrating the shell. In some embodiments, a relatively flexible shell can be used in combination with a harder shell. The flexible shell can be constructed from a hydrogel, a styrenic block copolymer (SBC), a silicone rubber, an elastomeric alloy, a thermoplastic elastomer (TPE), a thermoplastic vulcanizate (TPV) elastomer, a polyurethane elastomer, a block copolymer elastomer, a polyolefin blend elastomer, a thermoplastic copolyester elastomer, a thermoplastic polyamide elastomer, or a combination thereof. The flexible shell may also offer the benefit of a gasket to prevent liquid ingress between the shells.

[0060] FIG. 4 shows an example of a basic process 30 for forming an orthodontic appliance. As shown, material 32 can be formed into an orthodontic appliance 36. Material 32 can be one layer to form a single shell, or multiple, non-stick layers to form multiple shells at once. In this example process, tooth positioning device 36 can be made using a physical tooth model, or mold 34. Tooth positioning device 36 can be made by heating thermoformable material 32 and then vacuum or pressure forming the material over the teeth of physical tooth model 34. Tooth positioning device 36 is a direct representation of the physical tooth model. In some embodiments, material 32 is formed to the required dimensions (e.g., 120 mm and / or 125 mm diameter circles) for preparation on a commercially available forming device (e.g., Erkoform™, Erkoform-3dmotion™, Biostar™, Ministar S™, Drufomat Scan™, Drufosmart™, Essix™ SelectVac™). Guidelines for operating such molding devices can be found in: Scheu Dental Technology, Biostar Operating Manual, DE / GB / FR / IT / ES / 1.000 / 06 / 19 G REF PM 0113.01; Scheu Dental Technology, Application booklet for the pressure molding technique, GB 2.000 / 07 / 19 G REF 0111.02; Erkodent, Thermoforming, S15-3106-48; Erkodent, Erkoform 3D, 61-8002-2; Erkodent, Erkoform-3D+ Instructions, BA-Erkoform-3d+-anl-EN-04-04-2019, which are incorporated herein by reference.

[0061] Once formed, the shells can be affixed to one another depending on the desired working elasticity required for the patient. Methods of fastening include chemical bonding, localized melting, fixtures, and / or localized physical deformation to fasten the shells together, such as with pins. Before or after fastening occurs, excess material from the sheet can be trimmed to form the final tooth positioning device that can be used in the patient's orthodontic treatment. The edges of the shells can be sealed with a flexible material, such as silicone, to prevent liquid ingress.

[0062] One or a series of physical tooth models, such as the models described above, can be used in the creation of elastic repositioning appliances for orthodontic treatment. Similar to the process described above, each appliance can be created by thermoforming multiple layers of polymeric material over a mold of the desired tooth arrangement to form a dental appliance. Tooth positioning devices with the desired tooth arrangement typically fit the patient's teeth but are slightly out of alignment with the initial tooth configuration. When elastic positioners are placed over the teeth, controlled forces are applied at specific locations to gradually move the teeth to the desired configuration. This process is repeated with successive appliances with new configurations, ultimately moving the teeth through a series of intermediate configurations to the final desired configuration.

[0063] Throughout the above description, and for purposes of explanation, numerous specific details are set forth to provide a thorough understanding of the described technology. However, it will be apparent to those skilled in the art that these technologies may be practiced without some of these specific details. While various embodiments incorporating these teachings have been shown and described in detail, those skilled in the art can readily devise many other different embodiments or mechanisms to incorporate these technologies. Also, embodiments may include various, fewer, or more operations; or operations in a certain order, as described above. Therefore, the scope and spirit of the present invention should be determined in terms of the following claims, which follow as well as their legal equivalents.

Claims

1. a stack of polymeric shells, the stack of polymeric shells configured to have a cavity configured to receive a tooth, the stack of polymeric shells including a first shell, a second shell, and a third shell, the stack of polymeric shells having unattached and attached portions between adjacent ones of the first shell, the second shell, and the third shell; the first shell has a bottom first shell surface having a first cavity shaped to receive the tooth, a top first shell surface opposite the bottom first shell surface, and a first shell edge along which the bottom first shell surface and the top first shell surface meet; the second shell has a second cavity shaped to receive the first shell and a bottom second shell surface in contact with the top first shell surface, a top second shell surface opposite the bottom second shell surface, and a second shell edge to which the bottom second shell surface and the top second shell surface meet; the third shell has a third cavity shaped to receive the second shell and a bottom third shell surface in contact with the top second shell surface, an upper third shell surface opposite the bottom third shell surface, and a third shell rim to which the bottom third shell surface and the upper third shell surface meet; the affixed portion includes a plurality of discrete fastening portions between the first shell and the second shell; The affixed portion is disposed on at least one of the first and second shell edges such that at least one of the first and second shell edges includes a plurality of the discrete fastening portions. Dental orthodontic appliance.

2. the first shell, the second shell, and the third shell are constructed from the same type of polymeric material; 2. The orthodontic appliance of claim 1.

3. the orthodontic appliance consists only of the first shell, the second shell, and the third shell; 10. The orthodontic appliance of claim 1.

4. The attached portion includes less than 20% or less than 40% of the total area of ​​the bottom second shell surface, the upper first shell surface, the upper second shell surface, and the bottom third shell surface; 10. The orthodontic appliance of claim 1.

5. The non-attached portion is not glued or is rendered inseparable.

10. The orthodontic appliance of claim 1.

6. the affixed portion is positioned on the first shell edge such that the first shell edge includes a plurality of the discrete fastening portions; 10. The orthodontic appliance of claim 1.

7. The affixed portion is disposed on the second rim such that the second rim includes a plurality of the discrete fastening portions.

10. The orthodontic appliance of claim 1.

8. The affixed portion is disposed on the first edge, the second edge, and the third edge such that the first edge, the second edge, and the third edge include a plurality of the discrete fastening portions.

10. The orthodontic appliance of claim 1.

9. The distance between the first shell edge and the second shell edge is defined by a first uniform gap having a first uniform width.

10. The orthodontic appliance of claim 1.

10. The first shell edge and the third shell edge are separated by a second uniform gap having the first uniform width or the second uniform width.

10. The orthodontic appliance of claim 9.

11. the unattached portions between adjacent ones of the first shell, the second shell, and the third shell have the ability to be at least partially mechanically disengaged when the orthodontic appliance receives a tooth to generate increased working resiliency at the unattached portions between adjacent ones of the first shell, the second shell, and the third shell.

6. The orthodontic appliance of claim 5.

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