Movement compensation during aligner treatments

Abstract

The present disclosure discusses systems and methods for altering the position of a teeth in a subject with an aligner. In an embodiment, an aligner for altering the position of teeth of a subject includes a body comprising a movement contact surface and a compensation contact surface. The movement contact surface creates force on a tooth to move the tooth during use. The compensation contact surface creates force on the tooth to inhibit unplanned movement of the tooth during use.

Description

MOVEMENT COMPENSATION DURING ALIGNER TREATMENTSCross-Reference to Related Application

[0001] This application claims benefit and priority to U.S. Provisional Application No. 63 / 735,021, filed December 17, 2024, entitled “Movement Compensation During Aligner Treatments.” The content of which is incorporated herein by reference in its entirety

[0002] Field of the Technology

[0003] The present technology relates to dental appliance systems for altering the position of teeth in a subject. More specifically, this technology relates to the use of aligners having compensation contact surfaces that can be used to inhibit unplanned movement of a tooth.Background

[0004] Orthodontic aligners are appliances intended to make a series of discrete tooth position corrections aimed at aligning the teeth correctly. Aligners are equivalent to having bracket / wire braces for orthodontic treatment, but they have many advantages. For example, aligners are often transparent or semi-transparent, comfortable, and removable for cleaning and they allow a subject to eat anything they want.

[0005] Aligners are disposed on the outer surfaces of a tooth and apply forces to the tooth to alter the position of the tooth. When force is applied to the tooth, the force vector applied to the tooth is not always aligned with the center of mass of the tooth. This can cause unplanned movement of the tooth during the treatment step. Unplanned movement of a tooth leads to longer treatment time due, in part, to revisions to the treatment plan to correct the unplanned movements.Summary

[0006] The present technology can, in some embodiments, mitigate the problems associated with unplanned movement of teeth during treatment by creating a compensation contact surface into an aligner to inhibit unplanned movement of the teeth.

[0007] In an aspect of the present technology, an aligner is configured for controlled movement of one or more teeth. The aligner includes a body having a plurality of indentions that are configured to receive one or more teeth of the subject, wherein one or more of the indentations are shifted in position, in relation to the position of the teeth of the subject, to create contact surfaces between the aligner and one or more teeth. The aligner also includes a movement contact surface, wherein the movement contact surface creates force on a tooth to move the tooth during use. The aligner further includes a compensation contact surface, wherein the compensation contact surface creates force on the tooth to inhibit unplanned movement of the tooth during use.

[0008] The aligner can be configured to translate the tooth from a first position to a second position. The aligner can be configured to translate the tooth by 0.1 to 0.3 mm, although movements of less than 0.1 mm or greater than 0.3 mm can be planned. In this aspect, the compensation contact surface can apply a force to the tooth to inhibit rotation and / or extrusionintrusion of the tooth during translation.

[0009] In one aspect, the force created by the movement contact surface buccally or palatally / lingually translates the tooth from the first position to the second position during use, given favorable patient conditions and allowing enough time for bone remodeling. The compensation contact surface can create a buccolingual counterrotation moment during translation of the tooth. The aligner can be configured to buccally or palatally / lingually translate the tooth typically by 0.1 to 0.3 mm. The compensation contact surface can be configured to reduce the buccolingual moment by at least 50% or at least 80% compared to an aligner without a designed compensation surface. The aligner can further be configured to inhibit extrusion-intrusion of the tooth during translation.

[0010] In one aspect, the force applied by the movement contact surface can mesially or distally translate the tooth from a first position to a second position during use, given favorable patient conditions and allowing enough time for bone remodeling. The compensation contact surface can create a mesiodistal counterrotation moment during translation of the tooth. The aligner can be configured to mesially or distally translate the tooth typically by 0.1 to 0.3 mm. The compensation contact surface can be configured to reduce the mesiodistal moment by at least 50% or at least 80% compared to an aligner without a designed compensation surface. The aligner can further be configured to inhibit extrusion-intrusion of the tooth during translation.

[0011] In one aspect, the force applied by the movement contact surface can buccally or palatally / lingually translate the tooth from a first position to a second position during use, given favorable patient conditions and allowing enough time for bone remodeling. The compensation contact surface can create a mesiolingual or distolingual counterrotation moment during translation of the tooth. The aligner can be configured to buccally or palatally / lingually translate the tooth typically by 0.1 to 0.3 mm. The compensation contact surface can be configured to reduce the mesiolingual or distolingual moment by at least 50% or at least 80% compared to an aligner without a designed compensation surface. The aligner can further be configured to inhibit extrusion-intrusion of the tooth during translation.

[0012] In one aspect, the force created by the movement contact surface creates an extrusion movement or intrusion movement of the tooth and the compensation contact surface applies force to the tooth to inhibit rotation and / or translation of the tooth during extrusion or intrusion of the tooth during use. The aligner can be configured for extrusion or intrusion of the tooth by typically by 0.1 to 0.3 mm although movements of less than 0.1 mm or greater than 0.4 mm can be planned. In one aspect, the movement of the tooth is an extrusion of the tooth and the compensation contact surface creates a mesiodistal counterrotation moment. The compensation contact surface can be configured to reduce the mesiodistal moment by at least 50% or at least 80% compared to an aligner without a designed compensation surface.

[0013] In one aspect, the tooth comprises one or more engagers. The movement contact surface and / or the compensation contact surface can be modified to include an engager void configured to interact with an engager on a tooth during use.

[0014] In one aspect, the aligners described herein can be used to move one or more teeth of a subject by positioning the aligner on the teeth of the subject such that the movement contact surface and the compensation contact surface contact a tooth of the subject.

[0015] In one aspect, the aligner can be made from digital representations of a series of aligners. The method includes generating digital representations of a series of aligners that can incrementally move one or more teeth of a subject. One or more of the aligners in the series of aligners comprises a movement contact surface. The movement contact surface is positioned to create a force on a tooth of the subject to move the tooth during use. The digital representations of one or more of the aligners can be modified by adding a compensation contact surface. The added compensation contact surface creates a force on the tooth to inhibit unplanned movement of the tooth during use. The digital representations of one or more of thealigners can further be modified by altering the movement contact surface. Alteration of the movement contact surface counters some of the forces created by the compensation contact surfaces that effect the movement force created by the movement contact surface during use.

[0016] One or more of the aligners in the series of aligners are formed using the modified digital representations of one or more of the aligners. The aligners can be formed using a thermoforming process or by using a 3D printing process.Brief Description of the Drawings

[0017] The technology will be more fully understood from the following detailed description taken in conjunction with the accompanying drawings, in which:

[0018] FIGS. 1 A-1D depict typical unplanned movements which occur during common tooth movements using aligner technology,

[0019] FIG. 2A depicts a cross-sectional view of a central incisor tooth being palatally translated by a conventional aligner.

[0020] FIG. 2B depicts a schematic diagram of the forces applied to the tooth by the aligner depicted in FIG. 2A during the palatal movement of the tooth.

[0021] FIG. 2C depicts the final position and orientation of the tooth after multiple movement steps using the aligner described in FIG. 2A.

[0022] FIG. 3A depicts a cross-sectional view of a central incisor tooth being palatally translated by an aligner that includes a compensation contact surface.

[0023] FIG. 3B depicts a schematic diagram of the forces applied to the tooth by the aligner depicted in FIG. 3 A during the palatal movement of the tooth.

[0024] FIG. 3C depicts the final position and orientation of the tooth after multiple movement steps using the aligner described in FIG. 3 A.

[0025] FIGS. 4A and 4B depict comparisons of translation of a tooth by 1.4 mm, with and without a compensation contact surface.

[0026] FIG. 5 depicts a comparison of different compensation strategies that can be used for buccal translation of an incisor by 0.2 mm.Detailed Description

[0027] The present technology provides a method of moving a tooth in a controlled and directed manner to a desired position. The tooth is moved in a way that minimizes unplanned movements and maximizes the planned movements. An aligner can include a compensation contact surface that inhibits unplanned movement of the tooth during treatment.

[0028] Aligners, generally, can be used to alter the position of one or more teeth within a subject’s mouth. Aligners include a plurality of indentions and are configured to fit tightly on the subject’s teeth. Aligners are maintained on the teeth through an interference fit between the aligner and the teeth. Aligners also include some indentations that do not perfectly match the current shape or position of the patienf s teeth. The mismatch between the aligner and the teeth is predetermined so that the aligner applies pressure to specific teeth. In areas where the shape and position of the aligner does not match the current shape or position of the teeth, pressure areas between the aligner and the teeth are created. The forces applied at the pressure areas will trigger bone remodeling in the maxilla or mandibula, and, over time, teeth will shift position towards the shape and position dictated by the aligner. The specific force needed trigger bone remodeling results from a combination of specific pressure areas between that tooth and the aligner. The forces at the pressure areas are substantially greater than the pressure applied to the teeth through the interference fit.

[0029] The aligner covers the teeth and, optionally, a portion of the gums when inserted into the mouth. The aligners used in the present technology, are designed to provide forces to the teeth, at pressure areas created by contact of the aligner with the teeth, to direct the teeth to a more desirable configuration. After the subject’s teeth adjust to the new positions dictated by the aligner, the aligner may be replaced with a new aligner having a slightly different configuration which creates pressure areas that maintain forces on the teeth to continue movement of the teeth until the configuration dictated by the new aligner is achieved.

[0030] The aligners described herein cover either the maxillary teeth (top teeth) or the mandibular teeth (bottom teeth). Aligners can be made of any material suitable for dental applications. Preferably, aligners are composed of a clear material, particularly a polymeric clear material. The aligner material can be a unitary material (made, e.g., by a 3D printing process). Alternatively, the aligner material can be composed of multiple layers of one or more polymeric materials. Aligners can cover one or more of the teeth.

[0031] As used herein the term “distal” refers to the direction away from the midline along the arch curvature in each quadrant of a dentition. Each tooth can be described as having a distal surface and, for posterior teeth, a distobuccal (DB) and a distolingual (DL) corner or cusp tip.

[0032] As used herein the term “mesial” refers to the direction toward the midline in a dental arch. Each tooth can be described as having a mesial surface and, for posterior teeth, a mesiobuccal (MB) and a mesiolingual (ML) comer or cusp tip.

[0033] As used herein the term “anterior” refers to the direction toward the front of the head or the lips. The term anterior teeth refers to incisors and canines.

[0034] As used herein the term “posterior” refers to the direction toward the back of an individual's head. The term posterior teeth refers to premolars and molars.

[0035] As used herein the term “midline” refers to imaginary line dividing the left and right sides of the dentition.

[0036] As used herein the term “buccal” refers to the side of a tooth that is adjacent to (or the direction toward) the inside of the cheek.

[0037] As used herein the term “lingual” refers to the side of a tooth adj acent to (or the direction toward) the tongue (lingua). While formally, the term “lingual” is generally used when referring to teeth in the mandible (lower jaw), it is commonly used as a reference for teeth in either the mandible or the maxilla.

[0038] As used herein the term “palatal” refers to the side of a tooth adj acent to (or the direction toward) the palate. The term “palatal” is generally used when referring to teeth in the maxilla.

[0039] As used herein the term “apical” refers to the direction toward the root tip(s) or apex(es) of a tooth (the apices). It may also refer to something relating to the roots, such as apical support.

[0040] A used herein the term “occlusal” refers to the direction toward the biting surface of posterior teeth or something relating to this surface, such as the terms occlusal interference or occlusal surface. The term “coronal” is used similarly to refer to the direction toward the crown of a tooth (molars), as opposed to apical, which refers to the direction toward the tip(s) of the root(s) or apex(es). It may also refer to something relating to the crown, such as coronal forces.

[0041] As used herein the term “translation” refers to moving the tooth mesialdistal or buccolingual (out-in) so that the position of the tooth within the mouth is changed without rotation of the tooth.

[0042] As used herein the term “extrusion” refers to moving the tooth away from the gums of the mouth (occlusal direction). As used herein the term “intrusion” refers to moving the tooth toward the gums (apical direction).

[0043] As used herein, the phrase “movement of a tooth” refers to any change to the position, exposed height, or orientation of the tooth that is caused by the aligner. The term “movement” therefore encompasses translation, extrusion, intrusion, and rotation of the tooth.

[0044] The movement of a tooth by an aligner is determined by the forces acting on the tooth for sufficient time to allow the movement to happen. Tooth movement also requires a free path for the tooth to move into. Avoiding collisions with other teeth‘s roots or crowns play a crucial role as well for a successful single tooth movement. Bone health, height and density are also key variables influencing deeply tooth movement. Finally age and other cofactors such as the patient is a smoker or not, or other pathologies can affect deeply the quality of the expressed movement.

[0045] The forces acting on a tooth by an aligner can be characterized by force vectors and moments with respect to the center of resistance (CR) of the tooth. The CR is considered the fundamental reference point for controlled tooth movement. Typically, the CR is situated at a point located 1 / 3 to ’A of the distance from the alveolar crest to the root apex of the tooth. Force vectors include but are not limited to: mesiodistal force (Fmd); buccolingual force (Fbl); and apical-occlusal force (Fao). Moments include but are not limited to: buccolingual moment (Mbl); mesiodistal moment (Mmd); and mesiolingual / distolingual moment (Mmldl).

[0046] Mesiodistal forces (Fmd) applied to a tooth can translate the tooth toward the midline of the teeth (anteriorly), which is known as the mesial direction, or away from the midline, which is known as the distal direction. Mesiodistal forces can be used to translate a tooth along the gumline such that the tooth is evenly spaced between the adjacent teeth. As used herein, a positive mesiodistal force is used to designate movement in the distal direction. As used herein a negative mesiodistal force is used to designate movement in the mesial direction.

[0047] Buccolingual forces (Fbl) applied to a tooth can move the tooth toward the lips or cheeks (buccal direction) or toward the tongue / palate (lingual direction). Buccolingual forces are used to move a tooth in or out to align the tooth with the position of the adjacent teeth. As used herein a positive buccolingual force moves the tooth in the lingual direction. As used herein a negative buccolingual force moves the tooth in the buccal direction.

[0048] Apical-occlusal forces (Fao) applied to a tooth can move the tooth away from the gums of the mouth (occlusal direction, extrusion) or toward the root or gums of mouth (apical direction). Apical-occlusal forces are used to move a tooth into the gums of the patient or away from the gums. As used herein, a positive apical-occlusal force is used to designate movement in the occlusal direction. As used herein a negative apical-occlusal force is used to designate movement in the apical direction.

[0049] Rotational moment can also be applied to alter the position of a tooth. Buccolingual moment (Mbl) refers to a rotational moment applied to a tooth that causes the tooth to rotate about the mesiodistal axis around the center of resistance (CR). This type of rotation appears as a forward or backward rotation of the crown, also known as tipping of the crown. Forward rotation of the crown translates the occlusal surface of the tooth toward the lips (buccal crown tipping). Backward rotation of the tooth translates the occlusal surface of the tooth toward the tongue (lingual crown tipping). Buccolingual rotation can be used to align a long axis of the tooth running (i.e., an axis running from the apical end to the occlusal end) with the long axes of the adjacent teeth. As used herein, a positive buccolingual moment is used to designate buccal crown tipping. As used herein a negative buccolingual moment is used to designate lingual crown tipping.

[0050] Mesiodistal moment (Mmd) refers to a rotational moment that causes the tooth to rotate about the buccolingual axis (i.e., an axis extending from the buccal surface to the lingual surface of the tooth) around the center of resistance (CR) which appears as a sidewise tipping of the tooth. Rotation of the tooth such that the occlusal surface of the tooth moves in the mesial direction is known herein as mesial rotation or mesial crown tipping. Rotation of the tooth such that the occlusal surface of the tooth moves in the distal direction is known as distal rotation or distal crown tipping. Mesiodistal rotation can be used to rotate the tooth such that a long axis of the tooth is substantially perpendicular to the horizontal plane. As used herein, a positive mesiodistal moment is used to designate distal rotation. As used herein a negative mesiodistal moment is used to designate mesial rotation.

[0051] Mesiolingual / distolingual moment (Mmldl) refers to a rotational moment that causes the tooth to rotate about the long axis extending vertically through the tooth, around the center of resistance. This type of rotation appears as a rotation of the occlusal surface of the tooth. Rotation of the tooth such that the mesial surface rotates towards lingual is known herein as mesiolingual rotation. Rotation of the tooth such that the distal surface of the tooth rotates in a lingual direction is known as distolingual rotation. As used herein, a positivemesiolingual / distolingual moment (Mmldl) is used to designate mesiolingual rotation. As used herein a negative mesiolingual / distolingual moment (Mmldl) is used to designate a distolingual rotation.

[0052] Controlling each of the forces and moments applied to a tooth during treatment is an important factor for an efficient orthodontic correction of the teeth. Current aligners tend to apply forces that create moderate to large unplanned movements. The resulting unplanned movement of the tooth can result in suboptimal movements often leading to revisions of the aligner treatment plan. Multiple revisions per patients are common and accepted today as a side effect of aligner treatments.

[0053] Some typical unplanned movements which occur during common tooth movements using aligner technology are depicted in FIGS. 1 A-1D. FIG. 1 A depicts a schematic depiction of extrusion of a central incisor tooth. During extrusion of a central incisor tooth, unplanned mesial rotation (mesial tipping) can occur. FIG. IB depicts a schematic depiction of buccal translation of a premolar. During buccal translation of the premolar, unplanned buccal rotation can occur. FIG. 1C depicts a schematic depiction of mesial translation of a premolar. During mesial translation of the premolar, unplanned mesial rotation can occur. FIG. ID depicts a schematic depiction of palatal translation of a central incisor tooth. During palatal translation of the central incisor tooth, unplanned mesiolingual rotation can occur.

[0054] FIG. 2A depicts a cross-sectional view of a central incisor tooth 210 being palatally translated by a conventional aligner 200. Aligner 200 includes a movement contact surface 220 which creates forces on the tooth 210 to move the tooth toward the palate. In FIG. 2A, the aligner 200 and tooth 210 are depicted in an initial starting position. For illustrative purposes, a cross section of the tooth and a cross section of a portion of the aligner are superimposed in the figure. The depiction of the aligner represents the shape of the aligner before being applied to the teeth. As can be seen in this figure, a mismatch is created between the position of the tooth and the configuration of the aligner The intentional mismatch is used to induce forces on the tooth. The depiction of the tooth represents the starting position of the tooth. When a subject places the aligner over the tooth, the aligner deflects away from the tooth at the aligner surfaces that are depicted as overlapping the tooth. The inherent stiffness of the aligner, and the deflection of the aligner caused by the tooth when placed on the tooth, create a movement contact surface 220 which applies force to the tooth 210 to move the tooth. The aligner is further configured with an intentional gap 230 placed opposite to the movement contact surface to allow the tooth to move into the desired position.

[0055] FIG. 2B depicts a schematic diagram of the forces applied to the tooth by the aligner depicted in FIG. 2A during the palatal movement of the tooth. The movement contact surface provides translation force (F) to the tooth. The force (F), however, is not applied to the center of resistance of the tooth (CR) which is located at a position in the tooth underneath the gumline. The translation force (F) therefore also induces a buccal-lingual rotation about the center of resistance (CR) as illustrated in FIG. 2A. The result is that as the tooth is translated to the desired position the tooth is also buccal-lingually rotated. The final position of the tooth after translation using the aligner of FIG. 2A is shown in dashed lines in FIG. 2B.

[0056] In a typical procedure, a tooth is incrementally moved to the desired position. For example, a tooth may be moved by 1.4 mm in 0.2 mm steps. The movement process would therefore require 7 different aligners with each aligner configured to move the tooth by 0.2 mm. Without any sort of compensation, the unplanned movement of the tooth is cumulative with each step of the translation. FIG. 2C depicts the final position and orientation of the tooth after multiple movement steps. In FIG. 2C, the right representation 212 of the tooth represents the starting position of the tooth. The left representation 214 of the tooth represents the desired final position of the tooth after multiple translations. Superimposed over the starting position 212 and the final position 214, is the actual position of the tooth 216 after multiple treatment steps. As discussed above, the actual position of the tooth after treatment is buccal- lingually rotated (tipped) in the direction of rotation around the CR. The cumulative rotation of the tooth during movement can cause the tooth to not move correctly due to the rotation of the tooth causing the tooth to not properly fit into the aligner. This problem can lead to revisions of the treatment plan to correct the rotation of the tooth. Such revisions prolong the treatment by requiring the design and use of additional aligners to complete the movement.

[0057] Ideally, tooth translation occurs when the crown and root of a tooth move in the same direction and an equal distance. This happens when the force applied goes through the tooth's center of resistance (CR). Movement of a tooth with a conventional aligner causes movement of the crown of the tooth without significant movement of the root. For example, as shown in FIG. 2C, the root of the tooth is only slightly moved toward the desired location. Without movement of the root of the tooth, the tooth will be more prone to moving back to the original (starting) position after treatment is complete.

[0058] Current strategies for overcoming unplanned movement of the tooth include using auxiliaries to control the movement such as engagers, power bars, dimples, and other aligner alterations. Other strategies for overcoming unplanned movements include: reducing themovement rate; moving fewer teeth at the same time in each aligner step; or performing an overcorrection of 2-5 aligners at the end of the treatment. Such interventions are currently necessary to ensure the proper positioning of the teeth. These interventions, however, still suffer from some unplanned movements and typically cause the treatment to be extended to correct the unplanned movements.

[0059] The present technology overcomes the problems associated with unplanned movements of teeth during an aligner treatment plan by creating aligners having compensation contact surfaces. For example, instead of creating aligners with a shape that simply matches the target movement position of the teeth, the aligner will be designed to include compensation contact surfaces in specific positions, to minimize unplanned movements. The compensation will vary depending on the type of movement, the shape and location in the arch of the tooth, and the overall treatment planning. The compensation can be applied at each step of the treatment, not only at the end, therefore minimizing cumulative errors in the placement of the tooth during a series of aligner treatment steps.

[0060] In one aspect, the problems associated with unplanned movements of a tooth during aligner translation or extrusion / intrusion of a tooth can be overcome with the use of an appropriately positioned compensation contact surface or surfaces. FIG. 3A depicts a cross- sectional view of a central incisor tooth 310 being palatally translated by an aligner 300 that includes a compensation contact surface 340. As in the example depicted in FIG. 2A, aligner 300 includes a movement contact surface 320 which applies force to the tooth 310 to move the tooth toward the palate. In FIG. 3A, the aligner 300 and tooth 310 are depicted in an initial starting position. In contrast to the aligner depicted in FIG. 2A, aligner 300 includes a compensation contact surface 340.

[0061] FIG. 3B depicts a schematic diagram of the forces applied to the tooth by the aligner 300 during the palatal movement of the tooth. As depicted, the aligner creates two opposed forces to translate the tooth to the desired position without rotation. Force Fl represents the force created by the movement contact surface for translation of the tooth. Force F2 represents the force created by the compensation contact surface. In the present example, the compensation force F2 is being applied as a buccolingual counterrotation moment. F 1 is larger than F2, resulting in a net positive palatal force F of F=F1-F2 expressed at the CR. Fl, like in FIG. 2B, produces an unwanted palatal tipping, Ml, at the CR. F2 also generates a tipping at the CR, M2, but buccally instead of palatally. In this idealized example, the two tippings cancel each other out at the CR, Ml-M2=0, leaving only the force F acting on the tooth. Force F aloneacting on the tooth at the CR ensures a correct and pure translation without unwanted buccopalatal tipping.

[0062] In FIG. 3C, the right representation 312 of the tooth represents the starting position of the tooth. The left representation 314 of the tooth represents the desired final position of the tooth after multiple translations. Superimposed over the final position 314, is the actual position of the tooth 316 after multiple treatment steps. As can be seen in FIG. 3C, the use of a compensation contact surface eliminates unplanned rotation of the tooth as it is translated to the final position.

[0063] FIGS. 4A and 4B depict comparisons of translation of a tooth, with and without a compensation contact surface. In FIG. 4A the translation of a tooth is shown using a series of aligners having a configuration as depicted in FIG. 2A. The series of aligners depicted in FIG. 4A have a movement contact surface but do not have a compensation contact surface. The depicted treatment plan was intended to translate the tooth by 1.2 mm in 0.2 mm increments. Each aligner was therefore configured to translate the tooth by 0.2 mm. As shown in FIG. 4A, as the tooth is translated tipping occurs. The tipping is cumulative, meaning that the tipping from the first aligner is continued by in the second aligner. Tipping of the tooth also creates an unintentional mismatch between the aligner and the tooth. The unintentional mismatch occurs because the tooth is not in the expected position after an aligner treatment period is completed. The tooth does not sit in the proper position within the aligner, and the translation is slowed down. The entire process of translation, without compensation for the unintended rotation of the tooth, requires nine aligner steps to complete the desired movement. The first seven aligners are used to translate the tooth to the final position, and two aligners are added to correct the position of the tooth. As shown in FIG. 4A, the tooth, in the final position, is substantially rotated with respect to the desired orientation. Furthermore, while the tooth will appear to have been moved to the desired location, the root remains close to the original position. The treatment steps and / or time will therefore have to be extended to ensure that the tooth is fully moved to the new position.

[0064] FIG. 4B depicts an alternative treatment plan for the same 1.2 mm translation of the tooth. In this plan aligners that include a compensation contact surface (to compensate for the rotation / tipping of the tooth) are used. As can be seen from the figure, each step of the treatment plan moves the tooth with minimal or no unwanted rotation of the tooth. The use of a contact surface in each of the series of aligners, allows the tooth to be translated to the new position using less steps (seven) compared to the number of steps required withoutcompensation for rotation (nine). Furthermore, the result of the translation of the tooth using a compensation contact is correct and substantially matches the desired position and orientation of the tooth.

[0065] FIG. 5 depicts a comparison of different compensation strategies that can be used for buccal translation of an incisor by 0.2 mm. In the studies shown in FIG. 5, values of ±1.0 N are considered noise, and do not have a substantial effect on the movement or orientation of the tooth. In this comparison study, the goal is to maximize the buccolingual force (for translation of the tooth) while minimizing the other forces that can be applied to the tooth. As previously discussed, the main side effect that occurs during translation of a tooth is rotation (tipping) caused by a buccolingual moment. The primary goal of the compensation strategies that were implemented in this study is to reduce the buccolingual moment without effecting the buccolingual force.

[0066] Example A represents a classic 0.2 mm buccal translation with no compensation. As discussed with respect to FIGS 2A-2C, a large buccolingual moment is created when a buccolingual translation force is applied to the crown of the tooth. The large buccolingual moment creates substantial rotation (tipping) of the tooth during translation. Additionally, a significant intrusive force is applied to the tooth, causing the tooth to be pushed into the gum.

[0067] In Example B of FIG. 5, compensation forces are applied to correct the unplanned movements. To compensate for the unplanned movements, a compensatory extrusion force and compensatory buccolingual moment is created by the aligner. To create the compensation contact surface, the aligner is altered to apply a force opposite to the movement contact surface. For example B, the aligner was modified so that the compensation contact surface applies an extrusion force sufficient to pull the tooth 0.15 mm from the gumline. The extrusion force is intended to compensate for the intrusive force seen during uncorrected buccal translation. The compensation contact surface also applies a counterrotation buccolingual moment to the tooth sufficient to rotate the tooth 7.5°. Additionally, the movement contact surface is also modified. Because the compensation forces are applied to the opposing surface of the aligner (with respect to the movement contact surface), the buccolingual force would be significantly reduced, and the desired translation would not be achieved. In Example B, the movement contact surface is modified to create a theoretical buccal translation of 1.95 mm to compensate for the force generated by the compensation contact surface.

[0068] The resulting buccal translation for the compensations made in Example B of FIG. 5 exhibit substantially less unplanned motions than the uncorrected translation (Example A). The buccolingual force, required for buccal translation of the tooth is slightly reduced (from 12.4 N to 10.4 N) but is still sufficient to affect the desired translation of the tooth. More importantly, the buccolingual moment is reduced by about 65% (17.9 N cm to 6.3 N cm). The reduction in buccolingual moment allows the translation of the tooth to be accomplished with less tipping of the tooth during translation. The application of an extrusion compensation force had the intended purpose of eliminating the intrusion forces applied by the movement contact surfaces. However, the extrusion force applied to the tooth also created an unplanned slight extrusion of the tooth. The extrusion force, however, is relatively low (less than 3 N) and can be adjusted by modifying the compensation surface to apply less extrusion force to the tooth.

[0069] In Example C of FIG. 5, stronger correction forces are applied using the compensation contact surface to reduce the buccolingual moment further. In Example C, the aligner is further modified to increase the compensation for buccolingual moment. The aligner compensation contact surface is modified to apply 12° of buccolingual counterrotation. As discussed above, with respect to Example B, the movement contact surface will need to be modified to maintain the desired buccal translation of the tooth. In Example C, the aligner is modified to create a theoretical buccal translation of 3.0 mm. The aligner was also modified so that the compensation contact surface applies an extrusion force sufficient to pull the tooth 0.27 mm from the gumline, to compensate for the increased buccolingual force.

[0070] The resulting buccal translation using the compensations made in Example C of FIG. 5 exhibit substantially less unplanned motions than the uncorrected translation (Example A). The buccolingual force, required for buccal translation of the tooth is the same as the uncorrected example (12.4 N). The buccolingual moment is reduced by about 82% (17.9 N cm to 3.1 N cm). This reduction in buccolingual moment allows the translation of the tooth to be accomplished with almost no tipping of the tooth during translation. The application of an extrusion compensation force had the intended purpose of eliminating the intrusion forces applied by the movement contact surfaces. However, the extrusion force applied to the tooth also created an unplanned extrusion force on the tooth. The extrusion force, however, can be adjusted by modifying the compensation surface to apply less extrusion force to the tooth.

[0071] As shown in the examples above, unplanned movements of a tooth can be reduced or eliminated by creating a compensation contact surface in the aligner which provides a counter force or counter moment to the tooth to reduce the effect of unplanned forces applied to thetooth. During designed translation movements of a tooth the compensation contact surface can be used to inhibit rotation and / or extrusion-intrusion of the tooth. During designed extrusion or intrusion movements of the tooth the compensation contact surface can be used to inhibit rotation and / or translation of the tooth.

[0072] In one aspect, the movement contact surface of an aligner is configured to apply a force to buccally or palatally / lingually translate the tooth by at least 0.2 mm. The compensation contact surface is configured to create a buccolingual counterrotation moment. The compensation contact surface may also provide an apical force to counter extrusion of the tooth or an occlusal force to counter intrusion of the tooth. The compensation contact surface can be configured to reduce the buccolingual moment, produced by the movement contact surface, by at least 50%, by at least 60%, by at least 70%, by at least 80%, or by at least 90%, compared to an aligner without a designed compensation surface, during buccal or lingual / palatal translation of the tooth.

[0073] In one aspect, the movement contact surface of an aligner is configured to apply a force to mesially or distally translate the tooth by at least 0.2 mm. The compensation contact surface is configured to create a mesiodistal counterrotation moment. The compensation contact surface may also provide an apical force to counter extrusion of the tooth or an occlusal force to counter intrusion of the tooth. The compensation contact surface can be configured to reduce the mesiodistal moment, produced by the movement contact surface, by at least 50%, by at least 60%, by at least 70%, by at least 80%, or by at least 90%, compared to an aligner without a designed compensation surface, during mesial or distal translation of the tooth.

[0074] In one aspect, the movement contact surface of an aligner is configured to apply a force to buccally or palatally / lingually translate the tooth by at least 0.2 mm. The compensation contact surface is configured to create a mesiolingual or distolingual counterrotation moment. The compensation contact surface may also provide an apical force to counter extrusion of the tooth or an occlusal force to counter intrusion of the tooth. The compensation contact surface can be configured to reduce the mesiolingual or distolingual moment, produced by the movement contact surface, by at least 50%, by at least 60%, by at least 70%, by at least 80%, or by at least 90%, compared to an aligner without a designed compensation surface, buccal or lingual / palatal translation of the tooth.

[0075] In one aspect, the force applied by the movement contact surface creates an extrusion movement or intrusion movement of the tooth by at least 0.2 mm. The compensation contactsurface is configured to inhibit rotation and / or translation of the tooth during extrusion or intrusion of the tooth during use. For example, during extrusion of a tooth, the compensation contact surface creates a mesiodistal counterrotation moment. The compensation contact surface can be configured to reduce the mesiodistal moment, produced by the movement contact surface, by at least 50%, by at least 60%, by at least 70%, by at least 80%, or by at least 90%, compared to an aligner without a designed compensation surface, during extrusion / intrusion of the tooth.

[0076] It should be understood that the principles described herein to reduce unplanned movements can be applied to aligners used with one or more assistive elements. For example, an aligner that is used with one or more engagers can be modified as described herein to apply movement and compensation forces to the tooth. For example, if one or more engagers are present on a tooth, the movement contact surface and / or the compensation contact surface can include an engager void configured to interact with an engager on a tooth.

[0077] In an illustrative embodiment, the aligners described herein can be formed from biocompatible aligner materials. Examples of aligner materials include polyurethanes (e.g., Isoplast), epoxies, and metals. In an example, the aligner material can be clear or colored to allow for aligners with designs in them instead of a uniformly clear. The formation and use of aligners is generally described in U.S. Pat. Pub. US20120270173A1 by Pumphrey et. al., titled "Aligners for incrementally moving teeth, and methods and apparatus of making and using such aligners”, which is incorporated herein by reference.

[0078] The aligners described herein can be made using thermoforming processes or 3D printing technology. A series of aligners can be made using either process which allow incremental movement of the subject’s teeth to the desired positions.

[0079] To create an aligner using a 3D printer, a digital representation of one or more aligners in a series of aligners is obtained. A digital representation of an aligner can be produced by initially scanning the user’s teeth to create a 3D image of the teeth. Alternatively, a model of the users’ teeth can be made by preparing a polymeric resin impression of the teeth. A 3D digital model can be generated from the polymeric impression directly or by creating a model of the subject’s teeth and scanning the model. The digital model of the teeth is used to define one or more digital models of aligners that are used to guide the 3D printing process.

[0080] To create an aligner using a thermoforming process, a physical model of the user’s teeth can be prepared from a polymeric resin impression of the teeth or a digital scan of theteeth. A thin plastic film is then heated up and placed over the physical model. One or more thin films may be applied to the model to form the aligner.

[0081] For 3D printing methods, once a 3D digital model of the subject’s teeth is obtained, a treatment plan is developed. A treatment plan is a series of steps that are predetermined by the provider to reposition the teeth of the subject into a desired configuration. Each step of the treatment plan corresponds to a specific movement of one or more teeth of the subject by a series of aligners. The series of aligners can be created from the initial 3D digital model of the subject’s teeth. Each aligner in the system is created to have one or more mismatches between the current or projected configurations of the teeth, so that contact surfaces are created between the aligner and the teeth to induce movement of the teeth toward the final tooth position as defined by the aligner.

[0082] In either thermoforming or 3D printing processes, the desired movement of the teeth is broken down into a series of incremental steps designed to gradually move the subject’s teeth from the original position of the teeth, as defined by the 3D image of the subject’s teeth, to a final desired position of the teeth. The digital representation of the subject’s teeth can be used to generate a series of aligners that can incrementally reposition the teeth of the subject from the original position to the final position. The series of digital models of aligners is determined using a machine / software that runs a program that includes rules that provide the machine / software with a manner of evaluation and decision making. Some rules will define which teeth are best to be moved first, in a certain manner, and if multiple teeth can be moved at the same time with any given aligner in a sequence of aligners. The machine / software will perform assessments of the original teeth positions versus final teeth positions and perform calculations of what movement(s) are logically next in the sequence of aligners based on governing rules and parameters that serve as guidance for achieving optimally arranged teeth. In some implementations, identifying an arrangement of the second teeth alignment based on the first teeth alignment can be provided as an input performed manually by a provider. In this case, the number of iterative forces or movements required to cause the arrangement of the second teeth alignment can be determined based on the manually determined arrangement of the second teeth alignment.

[0083] Digital models of aligners can be created by using design software to create offsets (mismatches) between the teeth and the aligner for each of aligners in the series. The digital models can be designed, trimmed, smoothed, and modified using the design software.

[0084] In a 3D printing method, printing instructions for printing each aligner are determined from the digital models of the aligner created using the design software. In an exemplary embodiment, the printing instructions can include an ordering or sequence and timing of each additive manufacturing layer using a particular material within the alignment structure. In an exemplary embodiment, the printing instructions can be configured for a respective printer's capabilities to print with multiple materials, to resolve 3D objects into discrete volumetric pixels (“voxels”). Additionally, the printing instructions can provide for the method of additively manufacturing different materials (resins) at the correct location in such a way that the intended shape can be constructed with the designed features that are calculated for the aligner to accomplish predetermined movements of one or more teeth. In an example, the printing instructions can be configured to print on an additive manufacturing printer such as a Polyjet printer from Stratasys, Ltd. (Billerica, MA). Polymeric 3D printers that can be used to form aligners include, but are not limited to, fused deposition modeling (FDM) printers, stereolithography (SLA) printers, and selective laser sintering (SLS) printers. Further details for using 3D printing technology to form aligners can be found in U.S. Patent Application Publication No. 2020 / 0383754, which is incorporated herein by reference.

[0085] The aligner digital models are typically generated without consideration of the formation of compensation contact surfaces. In an embodiment, the aligner digital models are modified prior to 3D printing. The aligner digital models are modified to create compensation contact surfaces. The aligner digital models are further modified by altering the movement contact surfaces to counter the forces created by the compensation contact surfaces that effect the movement force created by the movement contact surface, for example, as discussed in the examples depicted in FIG. 5. The use of digital software allows the modification of the aligner digital models to be done prior to creating the aligners.

[0086] After the series of aligner digital models has been defined, the series of aligners is created using 3D printing technology or using thermoforming methods. The aligners are created using one or more of the modified digital representations.

[0087] Specific embodiments and methods of aligners having compensation contact surfaces have been disclosed. It should be apparent, however, to those skilled in the art that many more modifications besides those already described are possible without departing from the inventive concepts herein. The inventive subject matter, therefore, is not to be restricted except in the spirit of the disclosure. Moreover, in interpreting the disclosure, all terms should be interpreted in the broadest possible manner consistent with the context. In particular, theterms “comprises” and “comprising” should be interpreted as referring to elements, components, or steps in a non-exclusive manner, indicating that the referenced elements, components, or steps may be present, or utilized, or combined with other elements, components, or steps that are not expressly referenced.

Claims

CLAIMSWhat is claimed is:

1. An aligner configured for controlled movement of one or more teeth, the aligner comprising: a body comprising a plurality of indentions that are configured to receive one or more teeth of the subject, wherein one or more of the indentations are shifted in position, in relation to the position of the teeth of the subject, to create contact surfaces between the aligner and one or more teeth; a movement contact surface, wherein the movement contact surface creates force on a tooth to move the tooth during use; and a compensation contact surface, wherein the compensation contact surface creates force on the tooth to inhibit unplanned movement of the tooth during use.

2. The aligner of claim 1, wherein the controlled movement of the tooth translates the tooth from a first position to a second position, and wherein the compensation contact surface applies force to the tooth to inhibit rotation and / or extrusion-intrusion of the tooth during use.

3. The aligner of claim 2, wherein the force created by the movement contact surface buccally or palatally / lingually translates the tooth from the first position to the second position during use, and wherein the compensation contact surface creates a buccolingual counterrotation moment.

4. The aligner of claim 3, wherein the compensation contact surface reduces the buccolingual moment by at least 50% or at least 80% compared to an aligner without a designed compensation surface.

5. The aligner of claim 2, wherein the force applied by the movement contact surface mesially or distally translates the tooth from the first position to the second position during use, and wherein the compensation contact surface creates a mesiodistal counterrotation moment.

6. The aligner of claim 5, wherein the compensation contact surface reduces the mesiodistal moment by at least 50% or at least 80% compared to an aligner without a designed compensation surface.

7. The aligner of claim 2, wherein the force applied by the movement contact surface buccally or palatally / lingually translates the tooth from the first position to the second position during use, and wherein the compensation contact surface creates a mesiolingual or distolingual counterrotation moment.

8. The aligner of claim 5, wherein the compensation contact surface reduces the mesiolingual or distolingual moment by at least 50% or at least 80% compared to an aligner without a designed compensation surface.

9. The aligner of any one of claims 2-8, wherein the compensation contact surface creates an apical force to counter extrusion of the tooth or an occlusal force to counter intrusion of the tooth.

10. The aligner of any one of claims 2-9, wherein the aligner is configured to translate the tooth by at least 0.2 mm.

11. The aligner of claim 1, wherein the force created by the movement contact surface creates an extrusion movement or intrusion movement of the tooth, and wherein the compensation contact surface applies force to the tooth to inhibit rotation and / or translation of the tooth during extrusion or intrusion of the tooth during use.

12. The aligner of claim 11, wherein the movement of the tooth is an extrusion of the tooth and wherein the compensation contact surface creates a mesiodistal counterrotation moment.

13. The aligner of claim 12, wherein the compensation contact surface reduces the mesiodistal moment by at least 50% or at least 80% compared to an aligner without a designed compensation surface.

14. The aligner of any one of claims 11-13, wherein the aligner is configured to extrude the tooth by at least 0.2 mm.

15. The aligner of any one of claims 1-14, wherein the tooth comprises one or more engagers, and wherein the movement contact surface and / or the compensation contact surface comprises an engager void configured to interact with an engager on a tooth during use.

16. A method of movement of one or more teeth of a subject, comprising:obtaining an aligner as described in any one of claims 1-15; and positioning the aligner on the teeth of the subject such that the movement contact surface and the compensation contact surface contact a tooth of the subject.

17. A method of making an aligner as described in any one of claims 1-15, the method comprising: generating digital representations of a series of aligners that can incrementally move one or more teeth of a subject, wherein one or more of the aligners in the series of aligners comprises a movement contact surface, wherein the movement contact surface is positioned to create a force on a tooth of the subject to move the tooth during use; modifying the digital representation of the one or more aligners by adding a compensation contact surface, wherein the compensation contact surface creates a force on the tooth to inhibit unplanned movement of the tooth during use; and modifying the digital representation of the one or more aligners by altering the movement contact surface, wherein the alteration of the movement contact surface counters some of the forces created by the compensation contact surfaces that effect the movement force created by the movement contact surface during use.

18. The method of claim 17, wherein one or more of the aligners in the series of aligners are formed using the modified digital representations of one or more of the aligners.

19. The method of claim 18, wherein the one or more aligners are formed by a thermoforming process.

20. The method of claim 18, wherein the one or more aligners are formed by a 3D printing process. 1

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