WO2024206967A1 - Orthodontic appliances having non-affixed stacked shells - Google Patents

Abstract

An orthodontic appliance includes a plurality of shells shaped to receive teeth. The shells of the plurality have cavities that are similarly shaped to each other and to the teeth so as to enable the shells of the plurality to stack and form fit together. The plurality of shells are stacked and include at least one pair of adjacent shells that are non-affixed to each other and maintained stacked together by forces from being form fit together. The orthodontic appliance can be one of a series of similar appliances for incremental orthodontic modification or retaining of teeth.

Description

ORTHODONTIC APPLIANCES HAVING NON-AFFIXED STACKED SHELLS

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Application No. 63/493,660, filed March 31, 2023, the entirety of which is incorporated herein by reference.

FIELD OF TH E I NVENTION

[0002] The subject matter of the present disclosure relates generally to the field of orthodontic devices. More particularly, the present disclosure relates to user removable orthodontic appliances.

BACKGROUN D OF THE INVENTION

[0003] An objective of orthodontics is to move a patient's teeth to positions where function and/or aesthetics are optimized. Traditionally, appliances such as braces are applied to a patient's teeth by a treating practitioner and the set of braces exerts continual force on the teeth and gradually urges them toward their intended positions. Over time and with a series of clinical visits and reactive adjustments to the braces by the practitioner, the appliances to move the teeth toward their final destination.

[0004] More recently, alternatives to conventional orthodontic treatment with traditional affixed appliances (e.g., braces) have become available. For example, systems including a series of molded plastic aligners have become commercially available from Align Technology, Inc., San Jose, Calif., under the trade name Invisalign® System. The Invisalign® System is described in numerous patents and patent applications assigned to Align Technology, Inc. including, for example in U.S. Pat. Nos. 6,450,807, and 5,975,893.

[0005] The Invisalign® System typically includes 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 outset of treatment). Often, designing and planning a customized treatment for a patient makes use of computer-based 3-dimensional planning/design tools. The design of the aligners relies on computer modeling of the patient's teeth in a series of planned successive tooth arrangements, and the individual aligners are designed to be worn over the teeth, such that each aligner exerts force on the teeth and elastically repositions the teeth to each of the planned tooth arrangements. [0006] Currently, market-leading clear aligners have a layered construction of two or more layers of polymer materials that are affixed (or connected, bounded, etc.) together. A laminate, which includes the two or more affixed layers, is typically employed to thermoform a clear aligner. Laminate construction can be achieved by application of heat and pressure onto preformed sheets of material or as the laminate is extruded out of an extrusion machine. The lamination process results in the sheets or layers being bonded together on an intermolecular or intramolecular level. A disadvantage that exists today is the lack of availability of laminate materials that has varying laminate configurations such as the thicknesses of the individual layers and/or the polymer types across the individual layers. Although laminate materials produced by co-extrusion is a common practice worldwide, thin laminates of differing hardness values and/or materials in multilayer configuration are difficult to acquire because of lack of commercial availability, which is due to in-part, a high barrier to entry due to large capital investment costs combined with a relatively small market that impedes investment.

[0007] Like traditional braces, traditional aligners are required to be worn nearly constantly (20-22 hours a day), with breaks allowed for eating and cleaning teeth. Only small breaks are allowed because aligners do not have enough flexibility to account for teeth drifting out of alignment, which based on physical and material characteristics of the aligner. Increasing the working tolerance to account for higher drift requires increasing the working elasticity of an aligner, i.e., the amount an aligner can stretch to mount to teeth without causing permanent deformation, but a highly elastic aligner typically will not provide enough force to move teeth required for orthodontic treatment. Issues like these contribute to failed results or require restart of treatments because patients fail to wear the aligners according to prescribed requirements.

SUMMARY OF THE INVENTION

[0008] Embodiments of the 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.

[0009] In one aspect of the present disclosure, an orthodontic appliance is provided that includes a plurality of shells shaped to receive teeth. The plurality of shells are stacked and include at least one pair of adjacent shells that are non-affixed to each other.

[0010] In some embodiments, the plurality of shells are two shells that are stacked and non-affixed to each other. The two shells are sole shells of the orthodontic appliance. In some embodiments, the plurality of shells are three shells that are stacked and non-affixed to each other. The three shells are sole shells of the orthodontic appliance. In some embodiments, the plurality of shells are three or more shells that are stacked and nonaffixed to each other. In some embodiments, the plurality of shells further includes at least one pair of affixed shells.

[0011] In some embodiments, the plurality of shells are configured to extend successively closer to a gingiva line from a first shell configured to be closest to teeth to a second shell configured to be farthest from the teeth. In some embodiments, the plurality of shells are configured to extend successively closer to a gingiva line from a first shell configured to be farthest from teeth to a second shell configured to be closest to the teeth.

[0012] In some embodiments, the plurality of shells includes a first shell having a first edge and a second shell having a second edge. At a first coinciding point of the first and second edges, a first offset is formed between the first edge and second edge. The first offset is configured to face outward away from teeth. In some embodiments, the first offset is a value between 0.2 mm and 2.0 mm at the first coinciding point. In some embodiments, at a second coinciding point of the first and second edges, the first offset is configured to face inward toward the teeth. In some embodiments, at a third coinciding point of the first and second edges, the first offset is configured to be approximately zero such that the first and second edges are aligned.

[0013] In some embodiments, the plurality of shells includes a first shell having a first edge and a second shell having a second edge. At a first coinciding point of the first and second edges, a first offset is formed between the first edge and second edge. The first offset is configured to face inward toward teeth. In some embodiments, the first offset is a value between 0.2 mm and 2.0 mm at the first coinciding point.

[0014] In some embodiments, the plurality of shells includes a third shell having a third edge. At the first coinciding point, a second offset is formed between the first and third edges. The second offset is configured to face outward away from the teeth. In some embodiments, the second offset is a value between 0.2 mm and 2.0 mm at the first coinciding point. In some embodiments, at the second coinciding point, the second offset is configured to face inward toward the teeth. In some embodiments, at the third coinciding point, the second offset is configured to be approximately zero such that the first and third edges are aligned.

[0015] In some embodiments, the plurality of shells includes a third shell having a third edge. At the first coinciding point, a second offset is formed between the first and third edges. The offset is configured to face inward toward the teeth. In some embodiments, the second offset is a value between 0.2 mm and 2.0 mm at the first coinciding point.

[0016] In some embodiments, the plurality of shells includes at least one partially or completely translucent shell. In some embodiments, the plurality of shells includes a first translucent shell. The first translucent shell is configured such that the translucency extends toward a gingiva line without extending all the way to an edge of the first translucent shell. In some embodiments, a plurality of shells comprises at least one partially or completely translucent shell such that a teeth portion of the shell is translucent and a gingiva portion of the shell is non-translucent.

[0017] In another aspect of the present disclosure, methods are provided for making orthodontic appliances, such as the embodiments of orthodontic appliances described herein. In yet another aspect, systems are provided for repositioning teeth from an initial tooth arrangement to a final tooth arrangement are provided that include orthodontic appliances, such as the embodiments of orthodontic appliances described herein. The system can include, for example, a plurality of orthodontic appliances shaped to receive and reposition teeth or maintain the position of teeth. The plurality orthodontic appliances can include any of the various embodiments of the orthodontic appliances described herein. In yet another aspect of the present disclosure, methods for repositioning teeth from an initial tooth arrangement to a final tooth arrangement are provided. The method can include steps of incrementally using the system.

BRIEF DESCRI PTION OF DRAWINGS

[0018] For a better understanding of at least certain embodiments, reference will be made to the following Detailed Description, which is to be read in conjunction with the accompanying drawings.

[0019] FIG. 1 depicts an orthodontic appliance including non-affixed stacked shells, according to some embodiments.

[0020] FIG. 2 depicts an exploded view of an orthodontic appliance including non-affixed stacked shells, according to some embodiments.

[0021] FIG. 3A depicts an orthodontic appliance including only two stacked shells, which are non-affixed, according to some embodiments. FIG. 3B depicts a cross section at location C of the two shells of FIG. 3A, according to some embodiments. FIG. 3C depicts a cross section, taken at a similar location C shown in FIG. 3A, of an orthodontic appliance having only two shells that are stacked and non-affixed, according to an embodiment. FIG. 3D depicts a cross section, taken at a similar location C shown in FIG. 3A, of an orthodontic appliance having only two shells that are stacked and non-affixed, according to an embodiment.

[0022] FIG. 4A depicts an orthodontic appliance including only two shells, which are stacked and non-affixed, according to some embodiments. FIG. 4B depicts a cross section at the location C of the two shells of FIG. 4A, according to some embodiments.

[0023] FIG. 5A depicts an orthodontic appliance including three non-affixed stacked shells, according to some embodiments. FIG. 5B depicts a cross section of the three shells at a location C of the appliance of FIG. 5A, according to some embodiments. FIG. 5C depicts a cross section, taken at a similar location C shown in FIG. 5A, of an orthodontic appliance including three non-affixed stacked shells, according to an embodiment. FIG. 5D depicts a cross section, taken at a similar location C shown in FIG. 5A, of an orthodontic appliance including three non-affixed stacked shells, according to some embodiments. FIG. 5E depicts a cross section, taken at a similar location C shown in FIG. 5A, of an orthodontic appliance including three non-affixed stacked shells, according to some embodiments. FIG. 5F depicts a cross section, taken at a similar location C shown in FIG. 5A, of an orthodontic appliance including three non-affixed stacked shells, according to some embodiments.

[0024] FIGS. 6A and 6B depict orthodontic appliances having three shells, with one pair of adjacent shells being non-affixed and another pair of shells affixed, according to some embodiments.

[0025] FIG. 7 depicts an orthodontic appliance having three shells, with both pairs of the adjacent shells non-affixed and a pair of the non-adjacent shells affixed to each, according to some embodiments.

[0026] FIG. 8A depicts an orthodontic appliance having a translucent portion, according to an embodiment. FIG. 8B depicts an orthodontic appliance having a translucent shell that extends to the corresponding intersection of the teeth and the gingiva, according to some embodiments.

[0027] FIG. 9 depicts a diagram of a basic example process for forming an orthodontic appliance including non-affixed stacked shells, according to some embodiments

[0028] The figures depict various embodiments of the present invention for purposes of illustration only, wherein the figures use like reference numerals to identify like elements. One skilled in the art will readily recognize from the following discussion that alternative embodiments of the structures and methods depicted in the figures may be employed without departing from the principles of the invention described herein. DETAILED DESCRIPTION OF TH E INVENTION

[0029] Embodiments are disclosed that relate to orthodontic appliances constructed from multiple stacked shells that include at least one pair of adjacent shells that are non-affixed (or not affixed, unconnected, unbonded) to each other. In some embodiments, all shells in the stack are non-affixed to any other shell in the stack.

[0030] The term "affixed" is used herein to mean fixedly attached (or connected) in a permanent (or essentially permanent) manner, such as with adhesive, glue, bonding (e.g., intermolecular or intramolecular bonding), lamination, mechanical fasteners, etc. On the other hand, the term "non-affixed" is used herein to mean not fixedly attached to each other in a permanent (or essentially permanent) manner, such as with adhesive, glue, bonding (e.g., intermolecular or intramolecular bonding), lamination, mechanical fasteners, etc. It should be appreciated that almost any permanent connection can be broken, eventually break over time, weaken over time and separate, can be removed (e.g., mechanical fastener), etc. Thus, the term "permanent" is not intended to mean an absolutely permanent connection that is required to last indefinitely or that is impossible to break or separate. For example, adhesives, bonding, and mechanical fasteners can be used to fixedly attach the shells together in a permanent manner so they are inseparable unless broken or weakened as with an adhesive or bond, or broken or removed as with a mechanical fastener. The orthodontic appliances of the present disclosure have non-affixed shells that are non-affixed upon manufacture of the orthodontic appliance, in a state as intended for normal operation and use.

[0031] References to shells that are "non-affixed" or to "non-affixed shells" are used herein to mean that the shells are securely maintained (or held) in a stacked configuration (or arrangement) by the forces from being form fit (e.g., complementary shape and size) together without any adhesive (e.g., glue, etc.), any bonding (e.g., intermolecular or intramolecular bonding), or any mechanical fasteners that fixedly attach the shells together in a permanent (or essentially permanent) manner as described above. In this sense, the non-affixed shells may be referred to as being not affixed, unconnected, unbonded, etc. In certain instances, such as when the non-affixed shells are being flexed with a threshold amount of force, the non-affixed shells can move relative to one another yet still remain together in a stacked configuration because the shells are not affixed. This attribute can be beneficial for orthodontic appliances, especially with respect to a single shell at the same or similar thickness, by increasing flexibility or greater working elasticity while still possessing sufficient load force to properly move teeth as intended. [0032] The term, "working elasticity" is used here to refer to the capability of an orthodontic appliance to elastically deform to attach to an initial location of the teeth. This flexibility can allow an orthodontic appliance to obtain a greater range of initial tooth arranging (i.e., flexing) positions that differ from the appliance's target tooth arranging (i.e., resting) position. Additional possible benefits include greater break time (e.g., 8-12 hours) between required wear periods and greater latitude for patient non-adherence to required wear-times, and hence increased efficacy.

[0033] Shells that are non-affixed are positioned adjacent to one another and completely or partially abutting one another. In some embodiments, adjacent non-affixed shells can be completely abutting one another such that there is no space (or essentially no space) between the shells. In other embodiments, adjacent non-affixed shells can be partially abutting one another such that there is one or more pockets of space (e.g., areas of space) between the shells.

[0034] The term "non-affixed stacked shells" is used herein to refer to a stack of multiple shells (or a plurality of shells) that form the orthodontic appliance, wherein the multiple shells include at least one pair of adjacent shells that are non-affixed to each other. In some embodiments, all shells of the non-affixed stacked shells that form the appliance are nonaffixed to any other shell in the stack. For example, in some embodiments, the orthodontic appliance includes only two shells, which are stacked and non-affixed to one another. In other embodiments, the orthodontic appliance can include three or more shells, which are all stacked and non-affixed to any other shell. In some embodiments, the non-affixed stack shells can include at least one pair of non-affixed adjacent shells, as well as at least one pair of affixed shells, which can be adjacent or nonadjacent to each other. For example, a given shell (or alternatively, multiple given shells) can be stacked with, and non-affixed to, a stack of affixed shells. For instance, the given shell can be stacked with, and non-affixed to, an end shell (e.g., the top or bottom shell, and not a middle shell) of the stack of affixed shells. As another instance, the given shell can be stacked in between, and non-affixed to, two shells of a stack of affixed shells. For example, two affixed shells can be bonded near the edges such that a gap (or space) is formed between the two affixed shells; and further, before the two affixed shells are bonded, the given shell can be positioned within the gap while being stacked with, and non-affixed to, the two affixed shells. In other example embodiments, two stacks of affixed shells can be stacked together in a non-affixed manner.

[0035] Before the present invention is described in greater detail, it is to be understood that this invention is not limited to particular embodiments described, as such can, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting, since the scope of the present invention will be limited only by the appended claims.

[0036] Where a range of values is provided, it is understood that each intervening value, to the tenth of the unit of the lower limit unless the context clearly dictates otherwise, between the upper and lower limit of that range and any other stated or intervening value in that stated range, is encompassed within the invention. The upper and lower limits of these smaller ranges can independently be included in the smaller ranges and are also encompassed within the invention, subject to any specifically excluded limit in the stated range. Where the stated range includes one or both of the limits, ranges excluding either or both of those included limits are also included in the invention.

[0037] Unless defined otherwise, 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 methods and materials similar or equivalent to those described herein can also be used in the practice or testing of the present invention, representative illustrative methods and materials are now described.

[0038] It is noted that, as used herein and in the appended claims, the singular forms "a", "an", and "the" include plural referents unless the context clearly dictates otherwise. It is further noted that the claims may be drafted to exclude any optional element. As such, this statement is intended to serve as antecedent basis for use of such exclusive terminology as "solely," "only" and the like in connection with the recitation of claim elements or use of a "negative" limitation.

[0039] As will be apparent to those of skill in the art upon reading this disclosure, each of the individual embodiments described and depicted herein has discrete components and features which can be readily separated from or combined with the features of any of the other several embodiments without departing from the scope or spirit of the present invention. Any recited method can be carried out in the order of events recited or in any other order that is logically possible.

[0040] FIG. 1 depicts an orthodontic appliance 10 including non-affixed stacked shells, according to some embodiments. The orthodontic appliance 10 can be worn by a user (e.g., patient) in order to achieve an incremental repositioning of individual teeth (i.e., an "aligner") or for the purpose of retaining position of moved teeth after completion of an orthodontic treatment (i.e., a "retainer"). The oral appliance can fit over all teeth present in an upper or lower jaw 12, or less than all of the teeth in the upper or lower jaw 12. Various embodiments can enable tooth repositioning designed to apply repositioning forces to teeth. For example, the orthodontic appliance 10 can be worn by the user in order to achieve an incremental repositioning of individual teeth in the jaw 12 of the user. The orthodontic appliance 10 can include shells having teeth-receiving cavities that receive and resiliently reposition the teeth.

[0041] In some embodiments, only certain teeth received by an appliance will be repositioned by the appliance while other teeth can provide a base or anchor region for holding the appliance in place as it applies force against the tooth or teeth targeted for repositioning. In some cases, many or most, and even all, of the teeth will be repositioned at some point during treatment. Teeth that are moved can also serve as a base or anchor for holding the appliance as it is worn by the patient. Typically, no wires or other means will be provided for holding an appliance in place over the teeth. In some cases, however, it may be desirable or necessary to provide individual anchors on teeth with corresponding receptacles or apertures in the appliance so that the appliance can apply a selected force on the tooth. Basic methods for determining an orthodontic treatment plan using a series of incremented appliances as well as instructions for molding orthodontic appliances, are described in U.S. Pat. Nos. 6,450,807, and 5,975,893, which are incorporated by reference herein, but only to an extent that those patents do not contradict the newer teachings disclosed herein.

[0042] An orthodontic appliance can be designed and/or provided as part of a set of a plurality of appliances. In such some embodiments, each appliance may be configured so a tooth-receiving cavity has a geometry corresponding to an intermediate or final tooth arrangement intended for the appliance. The patient's teeth can be progressively repositioned from an initial tooth arrangement to a target tooth arrangement by placing a series of incremental position adjustment appliances over the patient's teeth. A target tooth arrangement can be a planned final tooth arrangement selected for the patient's teeth at the end of all planned orthodontic treatment. Alternatively, a 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 a target tooth arrangement can be any planned resulting arrangement for the patient's teeth that follows one or more incremental repositioning stages. Likewise, an initial tooth arrangement can be any initial arrangement for the patient's teeth that is followed by one or more incremental repositioning stages.

[0043] The orthodontic appliances can be generated all at the same stage or in sets or batches, e.g., at the beginning of a stage of the treatment, and the patient wears each appliance until the pressure of each appliance on the teeth can no longer be felt or has resulted in the maximum amount of expressed tooth movement for that given stage. A plurality of different appliances (e.g., set) can be designed and even fabricated prior to the patient wearing any appliance of the plurality. After wearing an appliance for an appropriate period of time, the patient replaces the current appliance with the next appliance in the series until no more appliances remain. The orthodontic appliances are generally not affixed to the teeth and the patient may place and replace the appliances at any time during the procedure (e.g., patient-removable appliances).

[0044] The final orthodontic appliance or several appliances in the series may have a geometry or geometries selected to overcorrect the tooth arrangement, i.e., have a geometry which would (if fully achieved) move individual teeth beyond the tooth arrangement which has been selected as the "final." Such over-correction may be desirable in order to offset potential relapse after the repositioning method has been terminated, i.e., to permit movement of individual teeth back toward their pre-corrected positions. Overcorrection may also be beneficial to speed the rate of correction, i.e., by having an appliance with a geometry that is positioned beyond a desired intermediate or final position, the individual teeth will be shifted toward the position at a greater rate. In such cases, the use of an appliance can be terminated before the teeth reach the positions defined by the appliance.

[0045] FIG. 2 depicts an exploded view of an orthodontic appliance including non-affixed stacked shells, according to some embodiments. In FIG. 2, an orthodontic appliance 10 is shown including a first shell 14 having an inner surface (also referred to as a teeth engaging surface, or a concave inner surface) that engages the teeth, and an outer surface (also referred to as an outer-shell engaging surface, or convex outer surface) on the opposite side. The orthodontic appliance 10 also includes a second shell 16 having an inner surface (also referred to as an inner-shell engaging surface, or a concave inner surface) and an outer surface (also referred to as a convex outer surface) on the opposite side that is exposed to the mouth. Optionally, one or more additional shells 18 can be located between the first shell 14 and the second shell 16, and have an inner surface (also referred to an inner-shell engaging surface, or a concave inner surface) and an outer surface (also referred to as an outer-shell engaging surface, or a convex outer surface). In some embodiments, the more shells that are used, the greater the working elasticity of the orthodontic appliance 10, assuming use of the same material for each shell. Moreover, it should be appreciated that the shells can fit over all teeth in the upper or lower jaw, such as shown in FIG. 2, or alternatively fit over less than all of the teeth in the upper or lower jaw (i.e., does not have to cover the whole dental arch). The shells can be configured to cover various parts of the dental arch for instance.

[0046] While the orthodontic appliance 10 is shown in an exploded view for the purpose of better understanding, the shells of the orthodontic appliance are intended to be stacked against each other. The shells include cavities (e.g., formed by the concave inner surfaces) that are similarly shaped to each other and to the teeth of the jaw, which enables them to be stacked with each other. For example, the similarly shaped shells can be manufactured and press fit together in a stacked configuration to create the orthodontic appliance, which can be then used in its intended purpose. Furthermore, the shells can vary in size in order to facilitate stacking. For example, a first shell that is stacked on a second shell (i.e., the first shell receives the second shell within its cavity) can be made (e.g., molded) slightly larger by at least a thickness of the second shell in order to receive and form fit to the second shell. In this way, each subsequent shell on the stack can be made progressively larger than the shell it is stacked on in order receive and form fit to the shell in which it is stacked. Put another way, each subsequent shell can be progressively larger by at least a total thickness of all the shells in which it is stacked on. After being stacked together, the cavities of the shells 14, 16, and 18 receive the teeth, with the cavity of the teeth engaging surface of the innermost shell (e.g., shell 14 in FIG. 2) engaging the teeth of the user to couple to the teeth.

[0047] The orthodontic appliance 10 includes shells (e.g., the shells 14, 16, and 18 of FIG. 2) that are stacked against each other with at least one pair of adjacent shells being nonaffixed to each other. In some embodiments, all shells of the non-affixed stacked shells that form the appliance 10 are non-affixed to any other shell in the stack. For example, in some embodiments, the orthodontic appliance includes only two shells, which are stacked and non-affixed to one another. Or, put another way, the two shells are the sole shells of the orthodontic appliance 10. In other embodiments, the orthodontic appliance 10 includes three or more shells, which are all stacked and non-affixed to any other shell. For example, the orthodontic appliance 10 can include only three shells, and are thus the sole shells in the orthodontic appliance.

[0048] In some embodiments, the non-affixed stacked shells can include at least one pair of non-affixed adjacent shells, as well as at least one pair of affixed shells, which can be adjacent or nonadjacent to each other. For example, a given shell (or alternatively, multiple given shells) can be stacked with, and non-affixed to, a stack of affixed shells. For instance, the given shell can be stacked with, and non-affixed to, an end shell (e.g., the top or bottom shell, and not a middle shell) of the stack of affixed shells. As another instance, the given shell can be stacked in between, and non-affixed to, two shells of a stack of affixed shells. For example, two affixed shells can be bonded near the edges such that a gap (or space) is formed between the two affixed shells; and further, before the two affixed shells are bonded, the given shell can be positioned within the gap while being stacked with, and nonaffixed to, the two affixed shells. In other example embodiments, two stacks of affixed shells can be stacked together in a non-affixed manner.

[0049] Since the shells are non-affixed, the flexibility and movement range is ultimately limited before separation occurs - e.g., past a threshold percentage of flexibility or threshold separation force to overcome the force of the form fit that holds the shells together. In some embodiments, the non-affixed stacked shells can be configured to shaped to accommodate attachments (or engagers) that may be fixed to the teeth. The attachments are used to apply a force to teeth. The attachments are not affixed to (e.g., with adhesives, with bonding, or mechanical fastened to) the shells.

[0050] While the non-affixed stacked shells enable movement and flexibility of non-affixed shells in the appliance, the flexural modulus of the appliance is not significantly impaired to serve the orthodontic purpose of aligning the teeth to the target position or maintaining the teeth in a desired position. In some implementations, the non-affixed stacked shells can provide greater working elasticity but a lower load force than a single shell appliance or a conventionally laminated stacked appliance at the same or similar thickness. For example, if a standard single shell or conventionally laminated aligner may have a thickness of 0.030 in. (or inches), the orthodontic appliance can include two non-affixed shells having approximate thicknesses of 0.015 in. each, or three non-affixed shells having approximate thicknesses of 0.010 in. each, and so on for greater numbers of non-affixed shells. The thicknesses of the non-affixed shells in the appliance do not have to be equal - i.e., the thicknesses of each non-affixed shell can vary from one another. For instance, in the first two-shell example having an overall thickness of 0.030 in., one shell can be 0.010 in. and the other shell can be 0.020 in., or some other variation of thicknesses to generate the desired thickness of 0.030 in. Any combination of thicknesses for each of the shells within any sized appliance (i.e., appliance with any number of shells) can be implemented to provide the minimum or desired thickness while providing the various optimal forces for moving teeth. In some implementations, the lower load force can provide the benefit of ensuring the teeth are moved without excessive force, while the flexibility enables greater movement range, which can be beneficial for compliance (e.g., user compliance in wearing the appliance for the intended duration or frequency). The thickness of each of the shells can vary from one another for the purpose of imparting a desired physical property or for varying desired physical properties. For example, the teeth-engaging shell can be made thinner than other shells in the appliance so that it can flex more than others.

[0051] Because the load force provided by the single shell appliance or a conventionally laminated stacked appliance is significantly higher than the minimum load force required to move teeth, the load force provided by non-affixed stacked shells of comparable thickness can still be greater than the minimum force required to move teeth. For instance, as a generalized example to facilitate understanding, if the minimum load force to move teeth is around 150 gram force, the load force provided by the single shell appliance of a typical material or a conventionally laminated stacked appliance may be around 800 to 900 gram force. Therefore, the load force from non-affixed stacked shells of the same or similar thickness can be less than 800 gram force but still remain above the minimum load force of 150 gram force. It should be appreciated that the values of the example provided are not intended to be limiting and that other values can be implemented without compromising the underlying principles of the present disclosure. Various design parameters of the nonaffixed shells (e.g., the material used to make the shells, thicknesses of the materials, etc.) can be implemented to provide a wide range of possible load forces above the minimum load force as desired.

[0052] In some implementations, each shell can be the same material or various materials that provide optimal forces for moving teeth (e.g., 5 different types of movements associated with orthodontics), patient comfort, and aesthetic appearance. In some implementations, an additional shell or shells can be added to carry the needed energy for added teeth movement.

[0053] ORTHODONTIC APPLIANCES INCLUDING ONLY TWO SHELLS

[0054] In one embodiment, the orthodontic appliance 10 includes only two stacked shells, which are non-affixed. FIG. 3A depicts an orthodontic appliance including only two stacked shells, which are non-affixed, according to some embodiments. In FIG. 3A, an orthodontic appliance 10a is shown including only two shells 14a and 16a, which are stacked together and non-affixed to each other. It should be appreciated that some of the features and variations discussed for FIG. 2 may also applicable here, and that all similar features and variation are not repeated here for the sake of brevity. For example, the shells 14a and 16a are stacked and include abutting adjacent surfaces. The abutting surfaces of the shells can be completely abutting with no space between the abutting surfaces, or partially abutting with one or more areas of spaces formed between the abutting surfaces.

[0055] The shell closer to the teeth (i.e., the shell 14a) extends farther toward the gingiva line of the jaw, which is represented by a dotted line 13. In this way, an edge 24a of the shell 14a is positioned closer to the gingiva line than an edge 26a of the shell 16a. The term "gingiva line" is used herein to refer to a line representing the general gingiva area of the jaw for directional purposes, and is drawn in the figures to approximate the corresponding location of a muco-gingival line. In some implementations, the shells of the orthodontic appliance are non-identical such that the shell with a greater surface area has a corresponding edge that extends to a position closer to the gingiva line than the edge of the shell with a smaller surface area.

[0056] An offset (or gap) is shown between the two edges 24a and 26a of the respective shells 14a and 16a, with the size of the offset indicated as distance D in FIG. 3A. The offset can vary along the appliance and the distance D can be measured at any "coinciding point" of the two edges 24a and 26a. For example, the distance D shown in FIG. 3A corresponds to the distance between the two edges 24a and 26b at the coinciding point along dotted line CP. The distance D can vary in different embodiments depending on various factors such as measurements of the shells, material properties of the shells, etc. Example distances D can include, but are not limited to, distances within the range of 0.01 mm to 0.5 mm, such as distances within the range of 0.03 mm to 0.3 mm, including distances within the range of 0.05 mm to 0.2 mm. In some embodiments, the distance D is between .07 mm and 0.13 mm, such as approximately 0.1 mm. In some implementations, the shell 14a is closer to the teeth and has a greater surface area than the shell 16a, resulting in edge 24a being closer to the gingiva line 13 than the edge 26a. FIG. 3B depicts a cross section at location C of the two shells of FIG. 3A, according to some embodiments. In FIG. 3B, the appliance 10a is shown along with the non-affixed and stacked shells 14a and 16a, which are configured such that an offset is formed by edges 24a and 26a and faces outward, away from the teeth T(as represented by the arrow at the offset). For instance, the offset in FIG. 3B forms steps that face outward, away from the teeth. The offsets correspond to the edges at the coinciding point at the cross section. It should be appreciated that all offsets shown in the cross section depictions in the figures herein correspond to the edges at the coinciding point at the cross section shown in the depiction.

[0057] In another embodiment, an edge of the shell farther from the teeth is positioned closer to the gingiva line than an edge of the shell closer to the teeth. For example, FIG. 3C depicts a cross section, taken at a similar location C shown in FIG. 3A, of an orthodontic appliance 10c having only two shells 14c and 16c that are stacked and non-affixed, according to an embodiment. In FIG. 3C, the shells 14c and 16c of orthodontic appliance 10c are stacked such that: the shell 16c is farther from the teeth and extends closer to the gingiva line 13 than the shell 14c; the edge 26c of the shell 16c is positioned closer to the gingiva line 13 than the edge 24c of the shell 14c; and, the offset formed by the edges 24c and 26c faces inward toward the teeth T (as represented by the arrow at the offset). The offset in FIG. 3C forms steps that face outward, away from the teeth. The example distances D discussed above for FIG. 3A are also applicable to the embodiment of FIG. 3C. In some implementations, the shell 16c is farther from the teeth 13 and has a greater surface area than the shell 14c, resulting in the edge 26c being positioned closer to the gingiva line 13 than the edge 24c.

[0058] In yet another embodiment, the distance D can be approximately zero such that the shell 16d farther from the teeth and the shell 14a closest to the teeth extend to the same approximate position from the gingiva line 13, with the respective two edges 26a and 24a positioned approximately aligned with each other, as shown in FIG. 3D. FIG. 3D depicts a cross section, taken at a similar location C shown in FIG. 3A, of an orthodontic appliance lOd having only two shells 14d and 16d, which are stacked and non-affixed, according to an embodiment. In FIG. 3D, the shells 14d and 16d are stacked such that the respective two edges 24d and 26d are positioned approximately aligned with each other such that the offset is zero (or approximately zero) and no steps are formed.

[0059] Providing offsets with a non-zero distance D (or gaps) create steps inward toward the teeth or outward away from the teeth. The offsets can be used to tune a flexural modulus of the orthodontic appliance, and can also result in less tongue irritation to the user that can occur due to material thickness where the distance D is zero and the edges are aligned at the same position. To alleviate irritation, the offsets can be placed in areas that face outward away from the teeth and inwards towards the mouth, resulting in stepped edges (e.g., edges 24a and 26a) facing the tongue. Alternatively, the offsets can be placed in areas that face inward toward the teeth, resulting in stepped edges (e.g., edges 24a and 26a) facing the teeth and only one edge (e.g., edge 16a) that can contact the tongue.

[0060] In some embodiments, the distance D of the offset can remain approximately uniform (e.g., a generally fixed distance) around the appliance from one distal end of the appliance (e.g., where the back most molar on the left side of the jaw would be) to the other distal end of the appliance (e.g., where the back most molar on the right side of the jaw would be).

[0061] In some embodiments, the distance D can vary around the appliance between distal ends. The distance D can be varied to tune the flexural modulus at different areas along the appliance between the distal ends. Furthermore, the distance D of the shells 14 and 16 can vary between distal ends to allow the respective edges 24 and 26 to change to and from any one of the following configurations any number of times: offset facing inward toward the teeth, offset facing outward away from the teeth, and offset equal to zero (i.e., aligned edges). For example, FIG. 4A depicts an orthodontic appliance including only two shells, which are stacked and non-affixed, according to some embodiments. In FIG. 4A, an orthodontic appliance lOe is shown having shells 14e and 16e, which are stacked and nonaffixed to each other. The shell 14e is closer to the teeth than the shell 16e. The shells 14e and 16e include respective edges 24e and 26e that vary with respect to their positions from the gingiva line 13. To facilitate understanding, the edge 24e is shown dotted while the edge 26e is shown solid. In section A, the edges 24e and 26e are aligned such that the distance Da of the offset between the edges 24e and 26e is approximately zero (or, put another way, no gap exists between the edges 24e and 26e). References to the "offset equal to zero" are used herein to mean the same as the "distance D of the offset is equal to zero." In section B, the shell 16e does not extend as far toward the gingiva line 13 than the shell 14e, and the edge 24e is positioned closer to the gingiva line 13 than the edge 26e by a distance Db. Further, the edges 24e and 26e form an offset that faces outward away from the teeth, and the size of the offset is distance Db in section B. In section G, the shell 14e does not extend as far toward the gingiva line 13 than the shell 16e, and the edge 26e is positioned closer to the gingiva line 13 than the edge 24e by a distance Dg. Further, the edges 24e and 26e form an offset facing inward toward the teeth, and the size of the offset is distance Dg in section G.

[0062] Furthermore, in some embodiments, the offsets and associated distances D on an outward-facing side of the appliance (or facing outward toward the cheeks and lips of a user) can independently vary from the offsets and distances D on an inward-facing side of the appliance (or facing inward toward the tongue and palate of the user). For example, the sections A, B, and C of FIG. 4A are shown on the outward-facing side of the appliance lOe. In section E of FIG. 4A, on the inward-facing side of the appliance lOe, the shells 14e and 16e are aligned such that the distance De of the offset between the edges 24e and 26e is approximately zero. In section F, on the inward-facing side of the appliance lOe, the shell 16e does not extend as far toward the gingiva line 13 than the shell 14e, and the edge 24e is positioned closer to the gingiva line 13 than the edge 26e with a distance Df of the offset. Furthermore, in section F, the edges 24e and 26e form an offset that faces outward away from the teeth, and the size of the offset is equal to distance Df.

[0063] FIG. 4B depicts a cross section at location C of the two shells of FIG. 4A, according to some embodiments. In FIG. 4B, the appliance lOe is shown along with the shells 14e and 16e, with the edges on the outward- and inward-facing sides distinguished from each other. The edges 24eout and 26eout of the respective shells 14e and 16e are on the outwardfacing side of the appliance lOe (or facing outward toward the cheeks and lips of a user). As shown in FIGS. 4A and 4B, the edges 24eout and 26eout are aligned such that their associated distance D of the offset is approximately zero (e.g., at the coinciding point of the edges at the cross section). On the other hand, the edges 24ein and 26ein (not shown in FIG. 4A) of the respective shells 14e and 16e are on the inward-facing side of the appliance lOe (or facing inward toward the tongue and palate of the user). As shown in FIG. 4B, on the inward-facing side of the appliance lOe, the shell 16e does not extend as far toward the gingiva line 13 than the shell 14e, and the edge 24ein is positioned closer to the gingiva line 13 than the edge 26ein by a distance De. Furthermore, the edges 24ein and 26ein form an offset that faces outward away from the teeth T with a size equal to distance De. The offsets correspond to the edges at the coinciding point at the cross section. It should be appreciated that all offsets shown in the cross section depictions in the figures herein correspond to the edges at the coinciding point at the cross section shown in the depiction. It should be appreciated that the distances D can be varied around the appliance between distal ends on the outward- and inward-facing sides of the appliance in any possible variations in different embodiments, and that all these possible variations are contemplated and within the scope of the present disclosure. For the sake of brevity, all possible variations are not shown.

[0064] ORTHODONTIC APPLIANCES INCLUDING THREE OR MORE SHELLS

[0065] In some embodiments, the orthodontic appliance can include three or more shells, with at least one pair of adjacent shells in the stack being non-affixed to each other. In some embodiments, all three or more shells are stacked and non-affixed to any other shell.

[0066] It should be appreciated that features and variations thereof that were discussed for the orthodontic appliances having only two shells, which are stacked and non-affixed (e.g., as discussed for the FIGS. 3A-D, 4A, and 4D) can also be analogously applied to orthodontic appliances having three or more shells, with at least one pair of adjacent shells in the stack being non-affixed. For example, in various embodiments, the shells can independently vary in how far they extend toward the gingiva line; the position of the edges can independently vary in closeness to the gingiva line; the offsets formed by edges can independently form offsets that face inward toward the teeth or that face outward away from the teeth; the size (or distance D) of different offsets can independently vary. Furthermore, these variations (e.g., variations in positions of the edges of the shells) can occur independently anywhere along the orthodontic appliance between the distal ends. Still further, these variations (e.g., variations in distances D of adjacent shells) can occur independently on inward- and outward-facing sides of the appliance. It should be appreciated that all possible variations can be analogously implemented in different embodiments, and such possible variations are contemplated for three or more shells and within the scope of the present disclosure. For the sake of brevity, all possible variations are not shown. Various example embodiments with three shells are shown in the following figures to facilitate understanding and are not intended to be limiting.

[0067] FIG. 5A depicts an orthodontic appliance including three non-affixed stacked shells, according to some embodiments. In FIG. 5A, an orthodontic appliance lOf has three shells 14f, 16f, and 18f. The shell 14f is closest to the teeth, the shell 18f is next closest shell to the teeth, and the shell 16f is farthest from the teeth, as similarly described in FIG. 2. It should be appreciated that some of the features and variations discussed for FIG. 2 may also applicable here, and that all similar features and variation are not repeated here for the sake of brevity. For example, the shells 14f, 16f, and 18f are stacked and include abutting adjacent surfaces. The abutting surfaces of the shells can be completely abutting with no space between the abutting surfaces, or partially abutting with one or more areas of spaces formed between the abutting surfaces.

[0068] In the embodiment shown in FIG. 5A, the shell 14f closest to the teeth extends closer to the gingiva Iinel3 than the shell 18f, which extends closer to the gingiva line 13 than the shell 16f. In this way, an edge 24f of the shell 14f is positioned closer to the gingiva line 13 than an edge 28f of the shell 18f, which is positioned closer to the gingiva line 13 than an edge 26f of the shell 16f. In the embodiment shown, the edges 24f, 26f, and 28f are not aligned such that: a distance D24-28 exists between the two edges 24f,28f of the respective shells 14f,18f; a distance D26-28 exists between the two edges 26f,28f of the respective shells 16f,18f; and a distance D24-26 exists between the two edges 24f,26f of the respective shells 14f,16f. Example distances D24-28 and D26-28 can include, but are not limited to, distances within the range of 0.01 mm to 0.5 mm, such as distances within the range of 0.03 mm to 0.3 mm, including distances within the range of 0.05 mm to 0.2 mm. In some embodiments, the distance DI and DI are between .07 mm and 0.13 mm, such as approximately 0.1 mm. In some embodiments, the shells of the orthodontic appliance are non-identical such that the shells with greater surface areas have corresponding edges that extend to positions closer to the gingiva line. For example, in some embodiments, the shell 14a is closest to the teeth and can have the greatest surface area of all shells, resulting in the edge 24a being closer to the gingiva line 13 than the edges 26a and 28a. Further, the shell 16a is furthest from the teeth and can have the smallest surface area of all shells, resulting in the edge 26a being further away from the gingiva line 13 than the edges 24a and 28a.

[0069] FIG. 5B depicts a cross section at a location C of the appliance lOf of FIG. 5A, according to some embodiments. In FIG. 5B, the appliance lOf is shown including the shells 14f, 18f, andl6f, which are stacked such that offsets are formed by respective edges 24f, 28f, 26f and face outward, away from the teeth T. The edge 24f is positioned closer to the gingiva line 13 than the edge 28f, which is positioned closer to the gingiva line 13 than the edge 26f. Distances D24-28, D26-28, and D24-26 of the offsets are also shown. The offsets correspond to the edges at the coinciding point at the cross section. It should be appreciated that all offsets shown in the cross section depictions in the figures herein correspond to the edges at the coinciding point at the cross section shown in the depiction.

[0070] In another embodiment, the three or more shells of the orthodontic appliance can include offsets that face outward away from the teeth. FIG. 5C depicts a cross section, taken at a similar location C shown in FIG. 5A, of an orthodontic appliance including three nonaffixed stacked shells. In FIG. 5C, an orthodontic appliance 10g includes only three shells 14g, 16g, and 18c that are stacked and non-affixed, according to an embodiment. In FIG. 5C, the shell 16g is farthest from the teeth T and extends closer to the gingiva line 13 than the shell 18g, which extends closer to the gingiva line 13 than the shell 14g, which is closest to the teeth T. The edge 26g of the shell 16g is positioned closer to the gingiva line 13 than the edge 28g of the shell 18g; and, the edge 28g of the shell 18g is positioned closer to the gingiva line 13 than the edge 24g of the shell 14g. Moreover, the offsets formed by the edges 24g, 28g, and 26g face inward toward the teeth T. The variations in distances D of the offsets as discussed above for the embodiment of FIG. 5A may also be applicable here to the embodiment of FIG. 5C. For the sake of brevity, not all variations are shown. In an implementation, the shell 16c is farther from the teeth 13 and has a greater surface area than the shell 14c, resulting in the edge 26c being positioned closer to the gingiva line 13 than the edge 24c. [0071] In other embodiments, the shells do not have to extend successively closer to the gingiva line 13b from the shell closest to the teeth to the shell farthest from the teeth, or vice versa. Any of the edges can be positioned relatively closer to, or farther from, the gingiva line with respect to any other edge, or positioned approximately aligned with any other edge. Furthermore, the relative positions of the edges of the shells can vary independently between distal ends of the appliance, as well as independently on the inward- and outward-facing sides of the appliance. While the following figures 5D-5F are provided as examples to facilitate understanding, it should be appreciated that the underlying principles of the present disclosure are not limited to the example embodiments shown. All possible variations are contemplated. FIG. 5D depicts an orthodontic appliance including three non-affixed stacked shells. In FIG. 5D, an orthodontic appliancelOh includes three non-affixed stacked shells 14h, 18h, and 26h, according to some embodiments. The shell 16h is farthest from the teeth T and includes an edge 26h that is positioned closest to the gingiva line 13. The shell 14h is closest to the teeth T and includes an edge 24h that is closer to the gingiva line 13 than an edge 28h of the shell 18h. The offset between edges 24h and 28h faces outward, away from the teeth, while the offset between edges 28h and 26h faces inward, towards the teeth. FIG. 5E depicts an orthodontic appliance lOi that includes three non-affixed stacked shells 14i, 18i, and 26i, according to some embodiments. The shell 16i is farthest from the teeth T and includes an edge 26h that is positioned farthest from the gingiva line 13. The shell 14i is closest to the teeth T and includes an edge 24i that is farther from the gingiva line 13 than an edge 28i of the shell 18i. The offset between edges 24h and 28h faces inward, toward the teeth, while the offset between edges 28h and 26h faces outward, away from the teeth. FIG. 5F depicts an orthodontic appliance lOj that includes three non-affixed stacked shells 14j, 18j, and 26j, according to some embodiments. The shell 16j is farthest from the teeth T and includes an edge 26j that is positioned farthest from the gingiva line 13. The shell 14j is closest to the teeth T and includes an edge 24j that is approximately the same distance to the gingiva line 13 than an edge 28j of the shell 18i - i.e., the edges 24j and 28j are aligned. The offset between edges 24h and 28h is zero and aligned, while the offset between edges 28h and 26h faces outward, away from the teeth.

[0072] The distances D24-28 , D26-28 , D24-26 can vary in different embodiments to provide desired values of flexural modulus and working elasticity, which may also take into account factors such as thicknesses of the shells, properties of the materials used for the shells, etc. Furthermore, as similarly discussed above for the distances D of the two nonaffixed stacked shells embodiments, the distances D24-28 and D28-26 can independently vary along the orthodontic appliance between the distal ends, as well as on the inward- and outward-facing side of the appliance. It should be appreciated that the distances D24-28 , D26-28 , D24-26 can be varied around the appliance between distal ends on the outward- and inward-facing sides of the appliance in any possible variations in different embodiments, and that all these possible variations are contemplated and within the scope of the present disclosure. For the sake of brevity, all possible variations are not shown.

[0073] VARIATIONS OF AFFIXED AND NON-AFFIXED SHELLS

[0074] As stated above, an orthodontic appliance having non-affixed stacked shells includes at least one pair of adjacent shells in the stack that is non-affixed to each other. For example, in FIGS. 3A-D and 4A-B, the orthodontic appliances shown include only two shells, which are adjacent, stacked, and non-affixed to each other.

[0075] In FIGS. 5A-F, for instance, the orthodontic appliances includes two pairs of adjacent shells: the shells 14 and 18, and the shells 18 and 16. In some embodiments, all shells 14,16, and 18 of the appliances are non-affixed to any other shell. In other embodiments, the appliances can include affixed (e.g., bonded, laminated, etc.) shells in addition to non-affixed shells. For example, one pair of adjacent shells can be non-affixed and the other pair of adjacent shells can be affixed, such as the shells 14 and 18 being non-affixed and the shells 18 and 16 being affixed, or vice versa. FIGS. 6A and 6B depicts an example orthodontic appliance having three shells, with one pair of adjacent shells being non-affixed and another pair of shells affixed, according to some embodiments. In FIG. 6A, an orthodontic appliance 10m is shown including: adjacent shells 18m and 16m non-affixed to each other; and, adjacent shells 14m and 18m affixed to each other, as represented by affixing points P. In FIG. 6B, an orthodontic appliance lOn is shown including: adjacent shells 14n and 18n nonaffixed to each other; and, adjacent shells 18n and 16n affixed to each other, as represented by affixing points P. The affixed shells of can be affixed together at one or more specific locations on their abutting surfaces, such as with bonding, adhesive, mechanical fastener at the affixing points P. Alternatively, the affixed shells can be affixed generally across the abutting surfaces, such as with bonding or adhesive spread between the affixed shells, or with lamination of the affixed shells.

[0076] In other embodiments, an orthodontic appliance can include at least one pair of adjacent shells that are non-affixed to each other, and at least one pair of non-adjacent shells that are affixed to each other. FIG. 7 depicts an orthodontic appliance lOo having three shells 14o, 16o, and 18o, with both pairs of the adjacent shells non-affixed and a pair of the non-adjacent shells affixed to each, according to some embodiments. In FIG. 7, an orthodontic appliance lOo is shown having both pairs of the adjacent shells (i.e., the shells 14o and 18o, and the shells 18o and 16o) that are non-affixed to each other. Further, the appliance lOo includes the non-adjacent shells 14o and 16o that are affixed to each other, as represented by the affixing points P. In such case, the shell 18o is positioned between, and non-affixed to, both of the shells 14o and 16o. The affixing points P are located at the ends of the shells 14o and 16o with a space (or gap) S located between the ends of the shell 18o and the affixing point P. Since the shell 18o is non-affixed to both shells 14o and 16o, the shell 18o can move relative to the shells 14o and 16o to provide flexibility and strength to the orthodontic appliance lOo. Orthodontic appliances with multiple shells bonded at or near their edges, and methods of making such appliances, can be found in U.S. Pat. No. 11,317,992, which is incorporated by reference herein, but only to an extent that the patent does not contradict the newer teachings disclosed herein.

[0077] It should be appreciated that the underlying principles taught here for three stacked shells are also applicable to other embodiments having four or more stacked shells. For the sake of brevity, all possible variations of the four or more stacked shells are not shown herein but should be understood to be contemplated along with their underlying concepts appreciated. In one embodiment, all of the four or more shells of the appliance are nonaffixed to any other shell. Furthermore, the orthodontic appliance having four or more stacked shells can include at least one pair of adjacent shells in the stack that is non-affixed to each other. Any combination of at least one pair of adjacent shells can be non-affixed to each other, such as in an analogous or similar manner to that described for the various combinations of three stacked shells. Moreover, any combination of affixed shells can be implemented within a stack of four or more stacked shells having at least one pair of nonaffixed shells, such as in an analogous or similar manner to that described for the various combinations of three stacked shells. Still further, any of the edges of the four or more shells can be positioned in any combination of relative closeness to the gingiva line with respect to any edge of the other shells, such as in an analogous or similar manner to that described for the various combinations of three stacked shells. For example, the shells can, but are not limited to, extending successively closer to the gingiva line from the shell closest to the teeth to the shell farthest from the teeth, or vice versa. Still further, the distances D of the offsets can vary independently around the appliance between distal ends of the appliance or on the inward- or outward-facing side of the appliance, such as in an analogous or similar manner to that described for the various combinations of three stacked shells. [0078] For the various orthodontic appliances having non-affixed stacked shells described herein, the thickness of each shell can vary in different embodiments as desired. For example, the total thickness of the shells of an orthodontic appliance can include, but is not limited to, a thickness within the range of 0.001 - 0.040 inches thick. The total thickness of the shells can be divided up into various thicknesses for each shell as desired, such as to provide a desired property (e.g., flexibility, translucency, etc.) to any of the shells. Furthermore, each of the shells can be constructed from a thermal plastic material, such as a polyester, a co-polyester, a polycarbonate, a thermoplastic polyurethane, a polypropylene, a polyethylene, a polypropylene and polyethylene copolymer, an acrylic, a cyclic block copolymer, a polyetheretherketone, a polyamide, a polyethylene terephthalate, a polybutylene terephthalate, a polyetherimide, a polyethersulfone, a polytrimethylene terephthalate or a combination thereof. For example, all shells can be made of the same material, or shells can be made of different materials. In some embodiments, one or more shells can be coated with lubricous materials or provided with surface treatments to decrease friction between the shells. In some embodiments, interior portions of the shells are treated with hydrophobic coatings to prevent liquid intrusion into the shells. In some embodiments, shells of relatively more flexibility can be used in conjunction with stiffer shells. For example, all shells may be rigid with varying degrees of flexibility. Flexible shells can be constructed from hydrogels, styrenic block copolymers (SBC), silicone rubbers, elastomeric alloys, thermoplastic elastomers (TPE), thermoplastic vulcanizate (TPV) elastomers, polyurethane elastomers, block copolymer elastomers, polyolefin blend elastomers, thermoplastic co-polyester elastomers, thermoplastic polyamide elastomers, or a combination thereof. Flexible shells may also provide the benefit of a gasket to prevent liquid intrusion between the shells.

[0079] TRANSLUCENCY

[0080] Light transmittance is the ratio of light intensity passing through a material to the intensity of light received by the specimen. Transmittance is determined by light reflection, absorption, and scattering at the material. A highly transparent material has very little absorptive and scattering properties. An opaque material transmits little to no light because of high scattering and absorptive qualities. Translucent materials have relatively high transmittance ratios, because of negligible absorption, but greatly scatter the transmitted light, resulting in a hazy, white appearance. Methods of making orthodontic appliances with translucent properties are known. For example, methods of making orthodontic appliances with translucent properties are described in U.S. Pat. No. 11,324,571, which is incorporated by reference herein, but only to an extent that the patent does not contradict the newer teachings disclosed herein.

[0081] In one aspect of the present disclosure, orthodontic appliances including non-affixed stacked shells are provided that include at least one shell that is partially or completely translucent. The translucent shell can have translucent appearance (or properties) that can be visually similar (as perceived by the human eye) to the appearance of natural teeth while mitigating gloss perceptions of prior art clear appliances. Furthermore, the translucent appearance one or more shells can be used to make teeth appear whiter. For example, in FIG. 3A for instance, either one of the shells 14a and 16a can be partially or completely translucent, or both shells 14a and 16 can be partially or completely translucent. In FIG. 5A for instance, any one of the shells 14f, 16f, and 18f can be partially or completely translucent; any two of the shells 14f, 16f, and 18f can be partially or completely translucent; or all of the shells 14f, 16f, and 18f can be partially or completely translucent. In some embodiments, one or more shells can be completely translucent or opaque to provide a desired appearance (e.g., color) to the orthodontic appliance.

[0082] For partially translucent shells, one or more portions (or areas) of the shell can be translucent and other portions of the shell non-translucent (e.g., transparent). For example, in some embodiments, the translucent portion of the shell can extend towards the gingiva line without extending to (or reaching) the edge of the shell. For instance, the translucent portion of the shell can extend toward the gingiva line but stop before the edge of the shell all the way between distal ends of the appliance, leaving a non-translucent portion (e.g., strip, section, etc.) at the edge and extending between the distal ends. FIG. 8A depicts an orthodontic appliance having a translucent portion, according to an embodiment. In FIG. 8A, an orthodontic appliance lOp is shown including non-affixed stacked shells 14p and 16p. The shell 14p that is closer to the teeth than the shell 16p. The shell 14p includes a translucent portion 80 and a non-translucent portion 84 (e.g., transparent portion). The translucent portion 80 extends towards the gingiva line 13 but does not extend all the way to the edge 24p. The translucent portion 80 extends from the edge 24p to the translucent portion 80. A dotted line 82 is shown where the translucent portion 80 and the non-translucent portion 84 meet. The transparent portion 84 can be configured to extend a distance that corresponds to the general area of intersection of the teeth and the gingiva. For example, the non- translucent portion 84 can be configured such that the dotted line 82 aligns with, approximates, or is near the intersection of the teeth and the gingiva. In this way, for instance, the non-translucent portion 84 can cover the general area of the gingiva while the translucent portion 80 covers the general area of the teeth so as to make the teeth appear whiter. Furthermore, the translucent portion and non-translucent portion of the shell can be positioned on either the inward-facing side of the appliance, outward-facing side of the appliance, or both.

[0083] In other embodiments, one or more shells can extend such that the edge of the shell generally aligns with intersection of the teeth and the gingiva. For example, FIG. 8B depicts an orthodontic appliance having a translucent shell that extends to the corresponding intersection of the teeth and the gingiva, according to some embodiments. In FIG. 8B, an orthodontic appliance lOq includes shells 14q and 16q, with the shell 14q being closest to the teeth, and the shell 16q being entirely translucent. An edge 26q of the shell 16q can extend to the intersection line 88 of the teeth and the gingiva as shown. In some instances, the shell 16q can be made to extend past the corresponding intersection, and thereafter be cut along the intersection line 88 of the teeth and gingiva.

[0084] In some embodiments, more than one shell of an appliance is partially or completely translucent. For example, multiple shells can each include one or more translucent portions. In some embodiments, an orthodontic appliance can include one or more translucent shells based on their position in the stack of shells. For instance, any translucent shell can be selected based on its relative position in the stack, such as: the shell closest to the teeth, the shell farthest from the teeth, or the shell located at a particular position between the shells closest to and farthest from the teeth.

[0085] In some embodiments, orthodontic appliances having non-affixed stacked shells, such as described herein, can include any combination of translucent shells and transparent shells. For instance, in the orthodontic appliances having three shells described in FIGS. 5A-F, the shell 14 and shell 18 can be transparent while the shell 16 can be a translucent, or any other combination. It should be appreciated that the other combinations of transparent and non-transparent shells are contemplated. For the sake of brevity are not all combinations are provided here.

[0086] In another aspect of the present disclosure, orthodontic appliances including nonaffixed stacked shells are provided that include at least one shell that is partially or completely opaque. Variations similar to the transparency embodiments discussed above can similarly apply to possible variations shells that are opaque. For the sake of brevity are not all provided here.

[0087] Some embodiments of orthodontic appliances of the present disclosure can include one or more transparent shells stacked with a translucent shell or an opaque shell. In some instances, this can reduce perceived glossiness by: including a thinner transparent shell (s) to reduce reflective gloss perceptions derived from light interaction between internal transparent surfaces; including a thinner transparent shell to reduce gloss perceptions derived from light interaction at inner and outer surface concavity changes; including an internal translucent or opaque shell to eliminate gloss perceptions derived from reflections of teeth surfaces; including an internal translucent shell to eliminate gloss perceptions derived from air gaps between the transparent shell and the translucent or opaque shell; including a translucent shell to eliminate gloss perceptions derived from light interaction with trapped saliva; and including a thinner transparent shell(s) to reduce gloss perceptions derived from light interaction at surface changes (i.e., hard surface lines at gaps between teeth, gumlines).

[0088] In some embodiments, a transparent shell is formed from a transparent polymer having low haze, high gloss, high transparency, high regular transmittance, and high total transmittance. For example, for a 0.010 inch (0.25 mm) sample light transmission values can include 0.5-1.5% Haze (ASTM D1003), >80 GU @ 45° (ASTM D2457), >80% transparency (ASTM D1746), >80% regular transmittance (ASTM D1003 modified), and/or >80% total transmittance (ASTM D1003 Modified)). In some embodiments, a transparent copolyester (e.g., Eastar™ copolyester 6763) can be used having the following properties: (for a 0.010 inch (0.25 mm) sample: 0.8 % Haze (ASTM D1003), 108 GU @ 45° (ASTM D2457), 85 % Transparency (ASTM D1746), 89% Regular Transmittance (ASTM D1003 Modified), 91% Total Transmittance (ASTM D1003 Modified)). In some embodiments, the transparent shell can be formed from one or more polymers. In some embodiments, to provide a long service life when the orthodontic appliance is a retainer, the transparent shell can be selected from materials having high impact resistance. In some embodiments, transparent shell can be made primarily or entirely from polyethylene terephthalate glycol-modified (PETG). In some embodiments, the transparent shell can be made primarily or entirely from polycarbonate. In some embodiments, the transparent shell can be made primarily or entirely from polymethylmethacrylate (PMMA). In some embodiments, the transparent shell can be processed to reduce or remove hydrophobic properties (e.g., from PETG) that can induce saliva foaming. In some embodiments, the transparent shell can be processed (e.g. rolled) to have a matte outer surface finish to reduce or remove hydrophobic properties. In some embodiments, the transparent shell can be processed with an acid or a base to reduce or remove hydrophobic properties. In some embodiments, first shell 14 and/or third shell 18 are covered with coatings or layers having hydrophilic properties. [0089] In some embodiments, the translucent shell can be formed from a semicrystalline thermal plastic material, a semi-compatible thermal plastic material, or an anti-phase material. In some instances, the translucent shell can be formed from one or more translucent polymers, which can provide a hazed white appearance. In some embodiments, the translucent shell can be primarily or entirely made of polyurethane, thermoplastic elastomer such as a thermoplastic copolyester (TPC/TPE-E) (e.g. Arnitel® EM400/EM460), maleic anhydride grafted polyethylene (HDPE) (e.g. Westlake Plastics® GB1002), or reactive terpolymer (e.g. Lotader® blends). In some embodiments, the translucent shell can be processed to increase crystallinity, thereby increasing light scattering to reduce transparency, increase translucence and provide a white or milky appearance. In some embodiments, the translucent shell can have greater flexibility (e.g., at least 1.5x less flexural modulus) to provide the appliance 10 with greater flexibility.

[0090] In some embodiments, the colorant can be integrated within the shell itself. For example, a dye, pigment, or other colorant can be blended or otherwise added to the material (e.g., thermal plastic materials) used to make a shell in order to provide color to some or all of the shell. For example, a colorant can be added to make the shell (or portions of the shell) a desired color (e.g., white) so that one or more teeth of the user appear the desired color (e.g., white). In some embodiments, an opaque shell can be an opaque or nearly opaque material, such as a polymer having a white colorant (e.g. titanium dioxide particles) or a metal foil. In some embodiments, a metal foil can be coated with titanium dioxide to provide a white appearance.

[0091] FIG. 9 depicts a diagram of a basic example process 30 for forming an orthodontic appliance, according to some embodiments. In FIG. 9, a process 30 is shown for forming a material 32 into a single shell 36 of an orthodontic appliance, such as an aligner, retainer, or other tooth positioning appliance. In some embodiments, the process 30 can be implemented to form the material 32 into any of the shells described herein or shown in the FIGS. 1-7. The material 32 can be of one layer to form a single shell 36. The type of material 32 used for each shell can vary depending on the shells purpose of the physical trait desired to be imparted on the shell. Furthermore, in some embodiments, a colorant (e.g., a dye, pigment, or other colorant) can be blended or otherwise added to the material 32 (e.g., thermal plastic materials) for the purpose of providing color the shell. For example, a colorant can be added to make the shell (or portions of the shell) a desired color (e.g., white) so that one or more teeth of the user appear the desired color (e.g., white). [0092] The various shells of a stacked non-affixed orthodontic appliance can be formed in a similar manner. In this example process, the orthodontic appliance 36 can be produced with the use of a physical tooth model, or mold, 34. The material 32 can be a thermoformable material, and the orthodontic appliance 36 can be produced by heating the thermoformable material 32 and then vacuum or pressure forming the material 32 over the teeth in the physical tooth model 34. The orthodontic appliance 36 is a direct representation of the physical tooth model. In some embodiments, a first shell can be formed, such as the shell configured to be closest to the teeth; and thereafter, the first shell can be positioned on the mold for a second shell to be formed. For example, another thermoformable material 32 can be heated and then vacuum or pressure formed over the first shell and mold. Then, the second shell can be positioned on the first shell and mold, and another thermoformable material 32 heated and vacuum or pressure formed over the second shell, first shell, and mold to form a third shell. This process can be repeated to provide the desired number of shells in the appliance. In this way, each subsequent shell on the stack can be progressively larger than the shell it is stacked on in order to receive and form fit to the shells in which it is stacked on.

[0093] In some embodiments that implement pockets of space between shells, a spacer can be positioned on the first shell when on the mold. The second shell can then be thermoformed over the spacer, first shell, and mold. In this way, the shape of the second shell is modified such that a pocket of space will be present where the spacer was when the first and second shells are stacked. These operations can be repeated for a third shell, fourth shell, etc.

[0094] In some embodiments, material 32 is dimensioned (e.g., 120mm and/or 125mm diameter circle) for ready processing on a commercially available forming device (e.g., Erkoform®, Erkoform-3dmotion®, Biostar®, Ministar S®, Drufomat Scan®, Drufosmart®, Essix® SelectVac®). Guidelines for operating such forming devices can be found at 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 moulding 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 by reference herein.

[0095] After formation, the multiple shells 36 of an orthodontic appliance can be pressed together to stack the non-affixed shells together and form the orthodontic appliance. Before or after the stacking of the shells takes place, excess material from the sheet can be trimmed to form a final appliance that can be used for orthodontic treatment of a patient. The edges of the shells can be cut at the appropriate distances as designed, such as shown and described for the distances D in the figures.

[0096] In another embodiment, the material 32 can include multiple non-affixed layers of material to form multiple non-affixed shells 36 at once. In an implementation, the multiple non-affixed shells 36 are formed to create the stack of non-affixed shells of the orthodontic appliance. In another implementation, one of the multiple non-affixed shells 36 can be combined with "other shells" to form an orthodontic appliance, such as to make multiple duplicate orthodontic appliances for instance. The "other shells" can also be made in a similar manner and all pressed together to form an orthodontic appliance having a stack of multiple shells that are all non-affixed to each other. In some implementations, the "other shells" can include any arrangement of affixed shells (e.g., bonded shells, laminated shells, etc.) with or without non-affixed shells. The shell 36 can then be pressed together with the "other shells" to be stacked with, and non-affixed to, the "other shells" having the arrangement of affixed shells. In some implementations, one or more shells 36 can be combined together to form an orthodontic appliance by: 1) pressing together at least one pair of adjacent shells 36 in the stack to be non-affixed to each other, and 2) bonding any shells 36 of the stack together (if affixed shells are present in the design or if desired). The bonding of any of the shells 36 can occur before or after the pressing together of the at least one pair of non-affixed adjacent shells 36. In this way, any of the varying arrangements of affixed and non-affixed shells can be created to form an orthodontic appliance. Methods of fixation include chemical bonding, localized melting, fasteners, and/or localized physical deformation to key the shells together. Before or after fixation takes place, excess material from the sheet can be trimmed to form a final tooth positioning appliance that can be used for orthodontic treatment of a patient. The edges of the shells can be sealed with a flexible material such as silicone to prevent liquid intrusion

[0097] One or a series of physical tooth models, such as the model described above, may be used in the generation of elastic repositioning appliances for orthodontic treatment. Similar to the process above, each of the appliances can be generated by thermoforming a multilayer polymeric material over a mold of a desired tooth arrangement to form a dental appliance. The tooth positioning appliance of the desired tooth arrangement generally conforms to a patient's teeth but is slightly out of alignment with the initial tooth configuration. Placement of the elastic positioner over the teeth applies controlled forces in specific locations to gradually move the teeth into the desired configuration. Repetition of this process with successive appliances comprising new configurations eventually moves the teeth through a series of intermediate configurations to a final desired configuration.

[0098] Throughout the foregoing description, and for the purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the described techniques. It will be apparent, however, to one skilled in the art that these techniques can be practiced without some of these specific details. Although various embodiments that incorporate these teachings have been shown and described in detail, those skilled in the art could readily devise many other varied embodiments or mechanisms to incorporate these techniques. Also, embodiments can include various operations as set forth above, fewer operations, or more operations; or operations in an order. Accordingly, the scope and spirit of the invention should be judged in terms of the claims, which follow as well as the legal equivalents thereof.

Claims

Claims

1. An orthodontic appliance comprising a plurality of shells shaped to receive teeth, wherein the shells of the plurality have cavities that are similarly shaped to each other and to the teeth so as to enable the shells of the plurality to stack and form fit together, and wherein the plurality of shells are stacked and comprise at least one pair of adjacent shells that are non-affixed to each other and maintained stacked together by forces from being form fit together.

2. The orthodontic appliance of claim 1, wherein the plurality of shells are two shells that are stacked and non-affixed to each other, and wherein the two shells are sole shells of the orthodontic appliance.

3. The orthodontic appliance of claim 1, wherein the plurality of shells are three shells that are stacked and non-affixed to each other, and wherein the three shells are sole shells of the orthodontic appliance.

4. The orthodontic appliance of claim 1, wherein the plurality of shells further comprises at least one pair of affixed shells.

5. The orthodontic appliance of claim 1, wherein the plurality of shells comprises a first shell having a first edge and a second shell having a second edge; wherein, at a first coinciding point of the first and second edges, a first offset is formed between the first edge and the second edge, the first offset configured to face outward away from teeth; and wherein, at a second coinciding point of the first and second edges, the first offset is configured to face inward toward the teeth.

6. The orthodontic appliance of claim 5, wherein the first offset is a value between 0.2 mm and 2.0 mm at the first coinciding point.

7. The orthodontic appliance of claim 5, wherein, at a third coinciding point of the first and second edges, the first offset is configured to be approximately zero such that the first and second edges are aligned.

8. The orthodontic appliance of claim 1, wherein the plurality of shells comprises adjacent first and second shells, the first shell having a first edge and the second shell having a second edge; wherein, at a first coinciding point of the first and second edges, a first offset is formed between the first edge and second edge; wherein the first offset is configured to face inward toward the teeth or outward away from the teeth; and wherein, at a second coinciding point of the first and second edges, the first offset is configured to be approximately zero such that the first and second edges are aligned.

9. The orthodontic appliance of claim 8, wherein the first offset is a value between 0.2 mm and 2.0 mm at the first coinciding point.

10. The orthodontic appliance of claim 1, wherein the plurality of shells comprises adjacent first and second shells, the first shell having a first edge and the second shell having a second edge; wherein, at a first coinciding point of the first and second edges, a first offset is formed between the first edge and second edge; wherein the first offset is configured to face inward toward the teeth or outward away from the teeth; and wherein the plurality of shells comprises a third shell having a third edge, the third shell adjacent to the second shell; wherein, at the first coinciding point, a second offset is formed between the first and third edges; and wherein the second offset is configured to face outward away from the teeth or inward toward the teeth, respectively.

11. The orthodontic appliance of claim 1, wherein the plurality of shells comprises at least one partially translucent shell that is configured such that the translucency extends toward a gingiva line without extending all the way to an edge of the first translucent shell.

12. The orthodontic appliance of claim 1, wherein the plurality of shells comprises at least one partially translucent shell such that a teeth portion of the shell is translucent and a gingiva portion of the shell is non-translucent.

13. The orthodontic appliance of claim 1 wherein, when flexed with a threshold amount of force, the at least one pair of non-affixed shells is movable relative to one another while still remaining stacked together.

14. The orthodontic appliance of claim 1, wherein thicknesses of the at least one pair of nonaffixed shells are not equal.

15. The orthodontic appliance of claim 1, wherein the plurality of shells comprises a first shell, a second shell, and a third shell; wherein the second shell is between and adjacent to the first and third shells, and wherein the first shell is affixed to the third shell.