Removable dental appliance with interproximal reinforcement - Patent application

Abstract

The removable dental appliance may include an appliance body configured to at least partially surround a plurality of teeth and an interproximal reinforcement. The appliance body may include a first shell shaped to engage a first tooth and a second shell shaped to engage a second tooth. The interproximal reinforcement extends along the interproximal region between the first tooth and the second tooth from a first gingival margin on the labial side of the appliance body to a second gingival margin on the lingual side of the appliance body. The interproximal reinforcement is configured to engage at least one of the lingual or labial surface of the first tooth below a contour height to enable the appliance body to cause movement of the first tooth toward a desired position. In certain embodiments, the present disclosure describes a method including determining, by a computer device, a removable dental appliance design including the same interproximal reinforcement.

Description

[Technical Field]

[0001] FIELD OF THE DISCLOSURE The present disclosure relates to polymer-based removable dental appliances, such as dental aligners. [Background technology]

[0002] The field of orthodontics is concerned with repositioning a patient's teeth to improve their function and aesthetic appearance. Orthodontic devices and treatment methods generally involve the application of forces to move the teeth into a proper occlusal configuration, or bite. As an example, orthodontic treatment may involve the use of slotted appliances known as brackets, which are fixed to the patient's anterior, cuspid, and bicuspid teeth. An archwire is typically placed in the slot of each bracket and serves as a track to guide tooth movement into a desired orientation. The ends of the archwire are usually received in appliances known as buccal tubes, which are fixed to the patient's molars. Such dental appliances remain in the patient's mouth and are periodically adjusted by an orthodontist to monitor the process and maintain appropriate pressure against the teeth until proper alignment is achieved.

[0003] Orthodontic treatment can also involve the use of alignment trays, such as bright or transparent polymer-based tooth-positioning trays, often referred to as clear tray aligners (CTAs). For example, orthodontic treatment with CTAs can include forming a tray with shells that engage one or more teeth. Each shell may be deformed from the tooth's initial position, e.g., a malocclusion. The deformed position of each shell of the CTA may apply a force to each tooth toward the tooth's desired position, which is an intermediate position between the initial position and the final position resulting from orthodontic treatment. However, orthodontic treatment may require some tooth movements that are difficult to achieve with CTAs, such as root movement and rotation of canines and premolars. In these instances, the forces and moments that a CTA can apply directly to the tooth surface may be insufficient to achieve the desired tooth movement. Summary of the Invention

[0004] Clear tray aligners often require attachments to achieve difficult tooth movements, such as root movement and tooth rotation. However, bonding the attachments to the teeth can be time-consuming and problematic. The attachments are aesthetically undesirable and make it difficult for patients to remove the aligner tray from the teeth. The disclosed removable dental appliances, including interproximal reinforcements, facilitate difficult tooth movements without requiring the use of dental attachments.

[0005] In some embodiments, the present disclosure describes a removable dental appliance including an appliance body configured to at least partially surround a plurality of teeth in a patient's dental arch and an interproximal reinforcement. The appliance body includes a first shell shaped to engage a first tooth of the plurality of teeth at an initial position of the first tooth and a second shell shaped to engage a second tooth of the plurality of teeth at an initial position of the second tooth. The second tooth is adjacent to the first tooth. The interproximal reinforcement extends along an interproximal region between the first and second teeth from a first gingival margin of the appliance body on a labial side of the appliance body to a second gingival margin of the appliance body on a lingual side of the appliance body. The interproximal reinforcement is configured to engage at least one of a lingual surface of the first tooth below a contour height of the first tooth or a labial surface of the first tooth below a contour height of the first tooth to enable the appliance body to apply a force vector at a contact point on the first tooth to move the first tooth toward a desired position of the first tooth when the removable dental appliance is worn by a patient.

[0006] In some embodiments, the present disclosure describes a method that includes creating a model of a patient's dental structure that provides desired positions for a plurality of teeth. The method also includes creating a removable dental appliance based on the model, the appliance including an appliance body configured to at least partially surround a plurality of teeth in the patient's dental arch and an interproximal reinforcement. The appliance body includes a first shell shaped to engage a first tooth of the plurality of teeth at an initial position of the first tooth, and a second shell shaped to engage a second tooth of the plurality of teeth at an initial position of the second tooth. The second tooth is adjacent to the first tooth. The interproximal reinforcement extends along an interproximal region between the first and second teeth from a first gingival margin of the appliance body on a labial side of the appliance body to a second gingival margin of the appliance body on a lingual side of the appliance body. The interproximal reinforcement is configured to engage at least one of a lingual surface of the first tooth below a contour height of the first tooth or a labial surface of the first tooth below a contour height of the first tooth to enable the appliance body to apply a force vector at a contact point on the first tooth to move the first tooth toward a desired position of the first tooth when the removable dental appliance is worn by a patient.

[0007] In some embodiments, the present disclosure describes a method including receiving, by a computing device, a digital representation of a patient's three-dimensional (3D) dental structure, the dental structure providing initial positions for a plurality of teeth. The method includes determining, by the computing device, a movement of a first tooth of the plurality of teeth from the initial position of the first tooth to a desired position of the first tooth. The method also includes determining, by the computing device, a force vector to be applied to a contact point on the first tooth to achieve the movement. The method also includes determining, by the computing device, a removable dental appliance design including positions of interproximal reinforcements on the removable dental appliance to induce the force vector, the removable dental appliance including an appliance body configured to at least partially surround the patient's plurality of teeth. The appliance body includes a first shell shaped to engage a first tooth of the plurality of teeth at the initial position of the first tooth and a second shell shaped to engage a second tooth of the plurality of teeth at the initial position of the second tooth. The second tooth is adjacent to the first tooth. The interproximal reinforcement extends along the interproximal region between the first tooth and the second tooth from a first gingival margin of the appliance body on a labial side of the appliance body to a second gingival margin of the appliance body on a lingual side of the appliance body. The interproximal reinforcement is configured to engage at least one of a lingual surface of the first tooth below a contour height of the first tooth or a labial surface of the first tooth below a contour height of the first tooth, such that the appliance body applies a force vector at a contact point of the first tooth to move the first tooth toward a desired position of the first tooth when the removable dental appliance is worn by a patient. The method also includes transmitting, by a computing device, a representation of the removable dental appliance to a computer-aided manufacturing system.

[0008] In some embodiments, the present disclosure describes a non-transitory computer-readable storage medium storing computer system executable instructions that, when executed, configure a processor to receive a digital representation of a patient's three-dimensional dental structure, the dental structure providing initial positions for a plurality of teeth. The non-transitory computer-readable storage medium also stores computer system executable instructions that, when executed, configure a processor to determine a movement of a first tooth of the plurality of teeth from the initial position of the first tooth to a desired position of the first tooth. The non-transitory computer-readable storage medium also stores computer system executable instructions that, when executed, determine a force vector applied to a contact point on the first tooth to effect the movement. The non-transitory computer-readable storage medium also stores computer system executable instructions that, when executed, configure a processor to determine a removable dental appliance design, including positions of interproximal reinforcements on the removable dental appliance, resulting in the force vectors, the removable dental appliance including an appliance body configured to at least partially surround the plurality of teeth. The appliance body includes a first shell shaped to engage a first tooth of the plurality of teeth at the first tooth's initial position, and a second shell shaped to engage a second tooth of the plurality of teeth at the second tooth's initial position. The second tooth is adjacent to the first tooth. The interproximal reinforcement extends along the interproximal region between the first tooth and the second tooth from a first gingival margin of the appliance body on a labial side of the appliance body to a second gingival margin of the appliance body on a lingual side of the appliance body. The interproximal reinforcement is configured to engage at least one of a lingual surface of the first tooth below a contour height of the first tooth or a labial surface of the first tooth below a contour height of the first tooth, such that the appliance body applies a force vector at a contact point on the first tooth to enable the first tooth to move toward a desired position of the first tooth when the removable dental appliance is worn by a patient. The non-transitory computer-readable storage medium also stores computer system executable instructions that, when executed, configure the processor to transmit a representation of the removable dental appliance to a computer-aided manufacturing system.

[0009] The details of one or more examples of the disclosure are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the disclosure will become apparent from the description and drawings, and from the claims. [Brief explanation of the drawings]

[0010] [Figure 1A] 1 illustrates an exemplary removable dental appliance including multiple interproximal reinforcements. [Figure 1B] 1 illustrates an exemplary removable dental appliance including multiple interproximal reinforcements. [Figure 1C] 1 illustrates an exemplary removable dental appliance including multiple interproximal reinforcements. [Figure 1D] 1 illustrates an exemplary removable dental appliance including multiple interproximal reinforcements. [Figure 1E] 1 illustrates an exemplary removable dental appliance including multiple interproximal reinforcements.

[0011] [Figure 2] FIG. 1 is a block diagram illustrating an exemplary computer environment in which a clinic and a manufacturing facility communicate information throughout the dental appliance manufacturing process.

[0012] [Figure 3] FIG. 1 is a flow diagram illustrating an exemplary process for generating digital dental structure data.

[0013] [Figure 4] FIG. 1 is a block diagram illustrating an example of a client computing device for generating digital dental structure data connected to a manufacturing facility via a network.

[0014] [Figure 5] FIG. 1 is a block diagram illustrating an exemplary computer-aided manufacturing system for constructing removable dental appliances.

[0015] [Figure 6A]FIG. 1 is a flow diagram illustrating a technique for manufacturing a set of removable dental appliances including interproximal reinforcements. [Figure 6B] FIG. 1 is a flow diagram illustrating a technique for manufacturing a set of removable dental appliances including interproximal reinforcements. [Figure 6C] FIG. 1 is a flow diagram illustrating a technique for manufacturing a set of removable dental appliances including interproximal reinforcements.

[0016] [Figure 7] FIG. 1 is a flow diagram illustrating successive iterations of treatment using a set of ordered removable dental appliances including interproximal reinforcements.

[0017] [Figure 8] FIG. 1 is a diagram showing the experimental setup for measuring the force applied to the root of a model first premolar by a removable dental appliance.

[0018] [Figure 9] 10 is a graph showing experimental results of the average measured force applied to the roots of a tooth model with a removable dental appliance including an interproximal reinforcement on the left first premolar and using an attachment on the model's right first premolar. [Figure 10] 10 is a graph showing experimental results of the average measured force applied to the roots of a tooth model with a removable dental appliance including an interproximal reinforcement on the left first premolar and using an attachment on the model's right first premolar. [Figure 11] 10 is a graph showing experimental results of the average measured force applied to the roots of a tooth model with a removable dental appliance including an interproximal reinforcement on the left first premolar and using an attachment on the model's right first premolar. [Figure 12] 10 is a graph showing experimental results of the average measured force applied to the roots of a tooth model with a removable dental appliance including an interproximal reinforcement on the left first premolar and using an attachment on the model's right first premolar. [Figure 13]10 is a graph showing experimental results of the average measured force applied to the roots of a tooth model with a removable dental appliance including an interproximal reinforcement on the left first premolar and using an attachment on the model's right first premolar. [Figure 14] 10 is a graph showing experimental results of the average measured force applied to the roots of a tooth model with a removable dental appliance including an interproximal reinforcement on the left first premolar and using an attachment on the model's right first premolar. [Figure 15] 10 is a graph showing experimental results of the average measured force applied to the roots of a tooth model with a removable dental appliance including an interproximal reinforcement on the left first premolar and using an attachment on the model's right first premolar. [Figure 16] 10 is a graph showing experimental results of the average measured force applied to the roots of a tooth model with a removable dental appliance including an interproximal reinforcement on the left first premolar and using an attachment on the model's right first premolar. [Figure 17] 10 is a graph showing experimental results of the average measured force applied to the roots of a tooth model with a removable dental appliance including an interproximal reinforcement on the left first premolar and using an attachment on the model's right first premolar. [Figure 18] 10 is a graph showing experimental results of the average measured force applied to the roots of a tooth model with a removable dental appliance including an interproximal reinforcement on the left first premolar and using an attachment on the model's right first premolar. [Figure 19] 10 is a graph showing experimental results of the average measured force applied to the roots of a tooth model with a removable dental appliance including an interproximal reinforcement on the left first premolar and using an attachment on the model's right first premolar. [Figure 20] 10 is a graph showing experimental results of the average measured force applied to the roots of a tooth model with a removable dental appliance including an interproximal reinforcement on the left first premolar and using an attachment on the model's right first premolar. DETAILED DESCRIPTION OF THE INVENTION

[0019] The disclosed removable dental appliances include interproximal reinforcements that facilitate difficult tooth movements using removable dental appliances without the use of dental attachments. Clear tray aligners (CTAs), a type of removable dental appliance, are often used with attachments bonded to tooth surfaces to achieve difficult tooth movements, such as root movement and tooth rotation. The attachments act as handles for the teeth. Corresponding receptacles or openings in the CTA engage with the attachments. The CTA can then apply forces and moments to the teeth via the dental attachments.

[0020] However, bonding attachments to teeth can be time-consuming and problematic. Typical tooth attachments are bonded to teeth with attachment trays containing pockets filled with composite restorations. The attachment trays are placed on the patient's teeth, and the composite restorations are bonded to the teeth. Underfilling, the pockets can result in attachment debonding from the teeth. Filling the pockets can result in excess composite restoration on the tooth surface (i.e., flash) that must be removed by grinding. If an attachment is not properly positioned or formed during the bonding process, the attachment may be removed by grinding off the composite restoration, and a new attachment is bonded to the tooth. Attachments that are not adequately formed and positioned on a tooth can impair the forces and moments that the CTA can apply to the tooth, which can result in undesired tooth positions at the end of orthodontic treatment. Additionally, during orthodontic treatment, the position of some teeth may lag behind the intended position in the treatment plan. Tooth positions may be delayed enough that the attachments on the teeth do not properly engage with the corresponding receptacles or openings in the CTA. In these situations, the CTA may not be effective in applying the desired force to the tooth attachments, and may apply force to the attachments in undesirable directions or at undesirable magnitudes that can strip the teeth from their desired positions in the treatment plan.

[0021] From the patient's perspective, dental attachments can be uncomfortable, for example, intruding on the tongue and inside the cheek, especially when the CTA is not in the mouth covering the attachment. Attachments can also be aesthetically undesirable because the attachment and the corresponding receptacle or opening in the CTA are more prominent than the smooth CTA surface that follows the natural contours of the tooth. Additionally, dental attachments make removal of the CTA from the tooth quite difficult. Patients must remove the CTA from their mouth every time they eat or perform oral hygiene tasks. Particularly when patients initially have attachments bonded to their teeth, they may find CTA removal frustrating, uncomfortable, and time-consuming. Attachments tend to violate the basic guarantee of the CTA as a fully removable appliance, potentially resulting in patient disappointment and resistance.

[0022] To improve the ability of removable dental appliances to facilitate difficult tooth movement without the use of dental attachments, the present disclosure describes removable dental appliances and orthodontic treatment techniques that include interproximal reinforcements. An exemplary removable dental appliance includes an appliance body configured to at least partially surround a plurality of a patient's teeth. The appliance body includes a first shell shaped to engage a first tooth of the plurality of teeth in its initial position, a second shell shaped to engage a second tooth of the plurality of teeth in its initial position, and an interproximal reinforcement. The first tooth is adjacent to the second tooth. The interproximal reinforcement extends along the interproximal region between the first tooth and the second tooth from a first gingival margin of the appliance body on a labial side of the appliance body to a second gingival margin of the appliance body on a lingual side of the appliance body. The interproximal reinforcement is configured to engage at least one of a lingual surface of the first tooth or a labial surface of the first tooth to enable the appliance body to apply a force vector at a contact point of the appliance body on the first tooth to move the first tooth toward a desired position of the first tooth when the removable dental appliance is worn by a patient. In some embodiments, the interproximal reinforcement is configured to engage at least one of a lingual surface or a labial surface of the first tooth that is lower than a contour height of the first tooth.

[0023] When the dental appliances are placed on the dental arch and the first and second teeth are received within the first and second shells of the removable dental appliance, the shells and interproximal braces deform to allow the first and second teeth to enter the shells. When the teeth are received within the shells, the interproximal braces urge the appliance body against the labial and lingual surfaces of the first or second tooth in the interproximal region. The interproximal braces may be configured to strengthen contact between the removable dental appliance and the first and second teeth below the respective contour heights of the respective teeth, for example, near the gingival margins of the respective teeth. Strengthening contact below the contour height increases retention of the removable dental appliance on the teeth and improves engagement between the removable dental appliance and the respective occlusal surfaces of the respective teeth. Strengthening contact below the contour height and increasing occlusal engagement improves the ability of the removable dental appliance to cause desired tooth movement without attachments on the teeth.

[0024] During use of the removable dental appliance, engagement of the removable dental appliance with the patient's teeth deforms at least a portion of the removable dental appliance, e.g., deforming the removable dental appliance from a physical configuration in which one or more of the patient's teeth are configured to be received within the shell of the removable dental appliance. Deformation of the removable dental appliance generates forces in the shell and / or interproximal braces, such as, for example, compressive, tensile, shear, bending, or torsional forces. The forces on the shell and / or interproximal braces can be restorative forces that bias the shell and / or interproximal braces in one or more directions that make the removable dental appliance less susceptible to deformation.

[0025] Restorative forces result in force vectors on one or more of the patient's teeth. For example, in the deformed configuration, each shell of a removable dental appliance engages with each tooth at one or more contact points through which the restorative forces are transmitted to the tooth. By strengthening tooth engagement near the gingival and occlusal surfaces, the interproximal brace improves the determinability of positional contact points, allowing for greater force moments, e.g., torque, to be applied to each tooth as the removable dental appliance moves from the deformed configuration toward the undeformed configuration. In this way, the interproximal brace improves the predictability of the magnitude and direction of tooth force vectors, causing bone remodeling near the roots of each tooth and resulting in desired tooth movement without the need for attachments to the teeth. Additionally or alternatively, the interproximal brace can reduce the rate of applied force degradation due to wear, material creep, stretching, moisture absorption, and the like. By maintaining the desired magnitude of force applied to the teeth for a longer period of time, the rate of tooth movement can be better maintained, reducing overall treatment time and / or increasing the duration that a single removable dental appliance can be used over the course of orthodontic treatment.

[0026] FIG. 1 shows a perspective view of an exemplary removable dental appliance 100 including multiple interproximal augments 102A-102E (collectively "interproximal augments 102"). The removable dental appliance 100 includes an appliance body 104 configured to at least partially surround multiple teeth in either the patient's maxillary or mandibular dental arch. For example, the appliance body 104 surrounds at least one of the facial, lingual, and occlusal surfaces of teeth 106A and 106B (collectively "teeth 106") in the patient's mandibular dental arch. In some embodiments, the appliance body 104 may surround different portions of different teeth 106 or overlap portions of the patient's gums. Although two teeth 106 are shown for illustrative purposes, the number of teeth 106 may include all of the patient's teeth 106, e.g., 14 teeth, fewer than 14 (e.g., a patient with one or more extracted teeth), or more than 15 (e.g., a patient with wisdom teeth or supernumerary teeth).

[0027] The removable dental appliance 100 may include an aligner tray. For example, the appliance body 104 may include a plurality of tooth shells 108A-108N (collectively "shells 108") and an interproximal reinforcement 102. Each respective one of the shells 108 is shaped to receive at least one respective one of the teeth 106. For example, shell 108D may be shaped to receive tooth 106A, and shell 108E may be shaped to receive tooth 106B. In some examples, the appliance body 104 may define a respective one of the shells 108 for each respective one of the teeth 106. In other examples, the appliance body 104 may define fewer shells than teeth; for example, a shell may receive two or more teeth, or at least one of the teeth 106 may not be surrounded by a shell of the shell 108. In other embodiments, the appliance body 104 may define more shells 108 than teeth 106, e.g., two or more shells or shell-like portions may surround at least one tooth or at least a portion of a shell in place and receive an unerupted tooth.

[0028] In some embodiments, each of the shells 108 can be shaped so that at least one inner surface of the shell contacts at least one selected location, selected surface area, or both of each of the teeth 106. In some embodiments, the shells 108 can surround a facial portion, a lingual portion, and an occlusal portion of the tooth 106. In some embodiments, the shells 108 can surround less of the tooth 106, such as only the facial portion and the lingual portion, or only one of the facial portion or the lingual portion of the tooth 106. By selecting the shape of each of the shells 108, the removable dental appliance 100 can control the location and direction of forces applied to each of the teeth 106. In some embodiments, the thickness of each of the shells 108 can range from about 0.1 millimeters to about 2.0 millimeters, such as from about 0.25 millimeters to about 1.0 millimeters, or from 0.30 millimeters to 0.75 millimeters, or about 0.5 millimeters.

[0029] In some embodiments, each of the shells 108 may include a surface that defines a cavity within the respective shell, the surface being shaped to receive a respective tooth in a desired position. For example, as best seen in FIG. 1D , shell 108E includes an inner surface 132 that defines a cavity 134 within shell 108E. Surface 132 is shaped to receive tooth 106B in the desired position of tooth 106B. For example, removable dental appliance 100 may bias occlusal surface 136 of tooth 106B from an initial position toward the desired position of tooth 106B such that occlusal surface 136 at least partially engages surface 132.

[0030] As shown in FIG. 1A , the appliance body 104 may include one or more anchor shells configured to receive one or more anchor teeth. In some examples, the anchor teeth may include one or more molars, premolars, or both, and the anchor shells may include corresponding shells, such as shells 108A-108D and 108K-108N. In other examples, the anchor teeth may include one or more anterior teeth, or a combination of one or more anterior and posterior teeth. The anchor shells may be configured to allow portions of the appliance body 104 to deform to provide sufficient force to move one or more teeth (e.g., sufficient force to cause alveolar bone remodeling) without providing sufficient force to move each anchor tooth. In other examples, the appliance body 104 may omit any one or more of the anchor shells 108A-108D and 108K-108N.

[0031] The appliance body 104 includes interproximal reinforcements 102. Each of the interproximal reinforcements 102 may be disposed between a respective adjacent shell 108. In some embodiments, each of the interproximal reinforcements 102 may be disposed on an outer surface of a respective shell 108, on both the outer surface and the inner surface of a respective shell (e.g., extending through a portion of the shell 108), or on the inner surface of a respective shell. The interproximal reinforcements 102 may extend along an interproximal region between a first tooth and a second tooth (e.g., an interproximal region 114 between teeth 106A and 106B) from a first gingival margin 110 of the appliance body 104 on a labial side 112 of the appliance body 104 to a second gingival margin 116 of the appliance body 104 on a lingual side 118 of the appliance body 104. 1B and 1C show that the interproximal reinforcements 102A and 102B can be configured to engage, via the shell 108D, the lingual surface 120 of the tooth 106A below the height of the tooth's 106A's contour 121, the labial surface 122 of the tooth 106A below the height of the contour 121, or both. The contour height (or curvature crest), e.g., the height of the tooth's 106A's contour 121, is the location on the tooth farthest from the root axis that has the greatest amount of curvature or maximum prominence or ridge. The region of the appliance body 104 below the contour height may include an undercut near the gingival margin. By engaging at least one of the lingual or labial surface of the tooth 106 below the contour height of the tooth 106, the appliance body 104 can enhance contact between the removable dental appliance 100 and the tooth 106 below the respective height of the tooth's contour.

[0032] Enhancing contact of the appliance body 104 where the tooth 106 is below the contour height can increase retention of the removable dental appliance 100 on the tooth 106 and improve engagement of the removable dental appliance 100 with the respective occlusal surfaces of the respective teeth. For example, enhancing contact below the contour height 121 of tooth 106A and increasing engagement of the occlusal surface 136 of tooth 106A can enable the removable dental appliance 100 to apply a force vector to contact points 123 on tooth 106A to move tooth 106A to a desired position when the removable dental appliance 100 is worn by a patient. In some examples, the interproximal reinforcements 102 can enable larger moments, e.g., torques, to be applied to the respective teeth, improving the determinability of position contact points, for example, when the removable dental appliance 100 moves from a deformed configuration to an undeformed configuration, or both, compared to a removable dental appliance without interproximal reinforcements. In this way, the interproximal reinforcement 102 improves control of the magnitude and direction of the force vector on the teeth 106, causing bone remodeling near the root of each tooth and resulting in the desired tooth movement without bonding attachments to the teeth.

[0033] The removable dental appliance 100 may be formed with an initial, undeformed shape corresponding to an intermediate or desired position of the tooth 106, such that the shape of the removable dental appliance 100 differs from the current position of the tooth 106. When the removable dental appliance 100 is worn by a patient, the appliance body 104 may deform to allow the shells 108 to receive the tooth 106. The deformation of the appliance body 104 may induce forces, such as at least one of compression, tension, shear, bending, and torsion, in one or more portions of the appliance body 104. In some embodiments, the force within the appliance body 104 may be concentrated within one or more shells 108. Each respective shell 108 may be engaged with a respective tooth of the teeth 106, and a force, including a force induced by the deformation of the appliance body 104, is transmitted to the respective tooth of the teeth 106 in each respective shell 108. In this manner, the deformation of the appliance body 104 can transmit a force to the tooth 106 through the shells 108.

[0034] The interproximal reinforcement 102 can affect the deformation of the appliance body 104. For example, without the interproximal reinforcement 102, the gingival portions of the appliance body 104 (e.g., the first gingival margin 110 on the labial side 112 and the second gingival margin 116 on the lingual side 118) (referred to herein as "gingival portions 110 and 116") can be more flexible than the occlusal surface 124 of the appliance body 104. The relative stiffness of the occlusal surface 124 can be due, at least in part, to the contoured surface of the occlusal surface 124 following the shape of the occlusal surface of the tooth 106. The relative flexibility of the gingival portions 110 and 116 can be due to less bending or folding near the gingival margin of the tooth 106. Additionally or alternatively, the appliance body 104 may be thicker near the occlusal surface 124 than near the gingival portions 110 and 116, with the thinner gingival portions 110 and 116 being more flexible than the thicker occlusal surface 124. The interproximal reinforcement 102 can stiffen the appliance body 104 in the gingival portions 110 and 116 near the interproximal reinforcement 102. For example, the interproximal reinforcement 102 can increase resistance to twisting about a path that follows the contour of the dental arch. In some embodiments, increasing the stiffness of the appliance body 104 with the interproximal reinforcement 102 can increase resistance to various other local (e.g., within each of the shells 108) or general (e.g., across the appliance body 104) bending and twisting movements. For example, the interproximal reinforcements 102A and 102B provide the appliance body 104 with greater stiffness in the interproximal region 114 than the labial surface 130 of the shell 108D, the lingual surface (not shown) of the shell 108D, or both. By strengthening the gingival portions 110 and 116, the appliance body 104 may have more uniform stiffness characteristics at the occlusal surface 124 and in the gingival portions 110 and 116 compared to a removable dental appliance without the interproximal reinforcements 102.

[0035] The relatively hard gingival portions 110 and 116 can improve the grip of the removable dental appliance 100 on the tooth 106. When the dental appliance is placed on the dental arch and the tooth 106 is received within the shell 108 of the removable dental appliance 100, the shell 108 and interproximal reinforcement 102 deform to allow the tooth 106 to enter the shell 108. For example, the profile height of the tooth 106A may be closer to the occlusal surface 126 of the tooth 106A than to the gingival margin 128 on the tooth 106A. The gingival portions 110 and 116 on the labial surface 130 and lingual surface (not shown) of the shell 108D can flex to allow the tooth 106A to enter the shell 108D. In some embodiments, the interproximal reinforcement 102A, the interproximal reinforcement 102B, or both, can flex to allow the tooth 106A to enter the shell 108D. After tooth 106A is received within shell 108D, interproximal reinforcement 102A, interproximal reinforcement 102B, or both, may urge the labial surface 130 and lingual surface of shell 108D toward the labial surface 122 and lingual surface 120 of tooth 106A, which are lower than the height of the contour 121 of tooth 106A. In this manner, interproximal reinforcement 102A improves engagement of the lower-than-contour height removable dental appliance 100.

[0036] In some examples, for example, reinforcing engagement of removable dental appliance 100 below the contour height by engaging the lingual and / or labial surfaces of each of teeth 106 can urge an occlusal portion of the inner surface of each of shells 108 toward the occlusal surface of the respective tooth. For example, interproximal augmentation element 102B, interproximal augmentation element 102C, or both, can urge the labial and lingual surfaces of shell 108E toward the labial and lingual surfaces 122 and 120 of tooth 106B below the contour 121 height of tooth 106B, thereby urging the occlusal portion of surface 132 toward occlusal surface 136 of tooth 106B. Forcing the occlusal portion of surface 132 toward occlusal surface 136 of tooth 106B can allow at least a portion of surface 132 to engage occlusal surface 136 of tooth 106. In some embodiments, the enhanced engagement below the tooth profile height of each of the teeth 106 and the enhanced engagement with the occlusal surfaces of each of the teeth 106 can enable the removable dental appliance 100 to form a force bond with the respective teeth. In some embodiments, the enhanced engagement below the tooth profile height of each of the teeth 106 and the enhanced engagement with the occlusal surfaces of each of the teeth 106 can improve the determinability of the contact points between the appliance body 104 and the teeth 106, for example, by concentrating the engagement at or near the occlusal and gingival portions of the teeth 106. In this manner, the interproximal reinforcement 102 can improve the engagement between the teeth 106 and the removable dental appliance 100 to cause movement of the teeth 106 without an attachment.

[0037] In some embodiments, the interproximal reinforcement 102 may be biased deeper into the interproximal space near the gingival portion of the tooth 106 than near the occlusal portion of the tooth 106 to improve engagement with the gingival portion of the tooth 106, the occlusal portion of the tooth 106, or both. For example, the interproximal reinforcement 102 may be biased outward along the height of the shell 108 (e.g., toward the outer surface of the appliance body 104) near the occlusal portion of the appliance body 104 and inward (e.g., toward the inner surface of the appliance body 104) near the gingival portion of the appliance body 104. The amount of bias near the occlusal surface of the appliance body 104 may include, for example, about 3 millimeters, such as about 1 millimeter to about 2 millimeters from the occlusal surface of the appliance body 104. The amount of bias near the gingival portion of the appliance body 104 can include, for example, about 3 millimeters, such as about 1 millimeter to about 2 millimeters from the gingival portion of the appliance body 104. Biasing the interproximal reinforcement 102 in this manner can further enhance engagement of the appliance body 104 with the gingival portion of the tooth 106, the occlusal portion of the tooth 106, or both, allowing for a greater moment on the tooth 106 compared to the appliance body 104 without the biased interproximal reinforcement 102.

[0038] The direction of the force on each of the teeth 106 may result in part from one or more contact points between at least one surface of each of the teeth 106 and at least one surface of each of the shells 108, and from the attachment points of the interproximal abutments 102 to the shells 108. In some embodiments, the number of contact points, the total area of ​​engagement, or both of each of the teeth 106 and each of the shells 108 may be greater than the number of contact points, the total area of ​​engagement, or both of a removable dental appliance without an interproximal abutment. For example, the force applied by the interproximal abutments 102 may be concentrated at the attachment points of each of the interproximal abutments 102 to the shells 108. Thus, the direction of the applied force on each of the teeth 106 may be selected by selecting the attachment points of one or more of the interproximal abutments 102 to the shells of the shells 108 that engage the teeth.

[0039] For example, a force distributed substantially evenly across the facial surface of tooth 106A can cause lingual translation of tooth 106A. Thus, to achieve translation of tooth 106A, interproximal reinforcements 102A and 102B can be shaped and attached to shell 108D to distribute the force substantially evenly across the facial surface of tooth 106A. A force concentrated on the mesial half of the facial surface of tooth 106A or one half of the facial surface and the opposite half of the lingual surface of tooth 106A can cause lingual rotation of tooth 106A about an axis of rotation extending generally in the occlusal-gingival direction. Thus, to achieve rotation of tooth 106A, interproximal reinforcements 102A and 102B may be shaped and attached to shell 108D to distribute force to half of the facial surface of tooth 106A or to one half of the facial surface and the opposite half of the lingual surface of tooth 106A. Force concentrated near the gingival margin (or gingival margin relative to the contour height) of tooth 106A may cause extrusion of tooth 106A. For example, about 3 millimeters, e.g., about 1 millimeter to about 2 millimeters, from the gingival or cervical margin of tooth 106A on either the dental or gingival side of the gingival margin line. Thus, to achieve extrusion, interproximal reinforcements 102A and 102B may be shaped and attached to shell 108D to concentrate force gingivally at the contour height of tooth 106A, e.g., to pinch or clamp both the lingual and facial sides of tooth 106A. Forces concentrated on both the facial and occlusal portions of a tooth can cause crown chipping in a lingual-gingival direction. The combination of forces concentrated on the facial occlusal surface of a tooth and forces concentrated on the lingual gingival surface of a tooth can cause tooth torque, causing the crown to move occlusally and the root to move facially.

[0040] As described above, each of shells 108 may include a surface defining a void therein, the surface being shaped to receive a respective tooth at a desired position. Appliance body 104 may be configured to apply a respective force vector at a respective contact point on each tooth relative to the void to move the respective tooth toward the void. For example, as shown in FIG. 1D , shell 108E includes an inner surface 132 defining a void 134 therein. Surface 132 is shaped to receive tooth 106B at a desired position for tooth 106B. In some examples, appliance body 104 may be configured to apply a force vector to contact point 123 on tooth 106B opposite portion 133 of void 134 to move tooth 106B toward portion 133 of void 134. In some examples, surface 132 of shell 108E can define second portion 135 of void 134, and appliance body 104 can be configured to apply a second force vector to a second contact point 125 on tooth 106B opposite second portion 135 of void 134 to move tooth 106B toward second portion 135 of void 134. In some examples, contact points 123 and 125 can be on opposite sides of tooth 106B. In some examples, contact points 123 and 125 can be on the same side of tooth 106B. In some embodiments, contact point 123 may be located near occlusal surface 136 of tooth 106B, such as on occlusal surface 136 or within about 3 millimeters (e.g., about 1 millimeter to about 2 millimeters) of the cusp crest, incisal edge, or marginal ridge of tooth 106B, and contact point 125 may be located near the gingival surface of tooth 106B, for example, within about 3 millimeters (e.g., about 1 millimeter to about 2 millimeters) of gingival margin 128 or cervical margin of tooth 106B, either dentally or gingivally of the line of gingival margin 128. In some embodiments, contact point 123 may be located on lingual surface 120 of tooth 106B, and contact point 125 may be located on labial surface 122 of the first tooth. In some embodiments, appliance body 104 may be configured to apply more than two force vectors at more than two contact points on each tooth to move each tooth toward one or more spaces.The shape of the voids can induce specific movement of each tooth by providing areas of reduced resistance, allowing each tooth of the teeth 106 to move in response to a force vector applied to the respective tooth when the removable dental appliance 100 is worn by a patient. In this manner, the voids within the appliance body 104 can assist in biasing each tooth of the teeth 106 toward a desired position.

[0041] Other force vectors and combinations of force vectors are contemplated that may result in one or more tooth movements. For example, Table 1 includes the type of desired tooth movement, the respective thresholds for each movement, and exemplary positions of the interproximal reinforcement relative to the moved tooth to achieve each movement. [Table 1]

[0042] In some embodiments, each threshold for each tooth movement indicates a threshold (minimum) amount of tooth movement for which the interproximal reinforcement 102 can be used to ensure predictable completion of tooth 106 movement. By selecting the shape of the interproximal reinforcement 102 and the position of the interproximal reinforcement 102 on the shell 108, the removable dental appliance 100 can be configured to apply a force having a particular direction and magnitude to the tooth 106 via deformation of the interproximal reinforcement 102, which can result in any one or more of a corresponding rotational force, translational force, extrusion force, intrusion force, chipping force, or torqueing force on the tooth 106.

[0043] Each interproximal reinforcement of the interproximal reinforcement 102 may extend over at least a portion of a respective interproximal region, e.g., the interproximal region 114 between the first tooth 106 and the second tooth 106, e.g., between tooth 106A and tooth 106B. The interproximal reinforcement 102, e.g., interproximal reinforcement 102B, may include any suitable shape. In some embodiments, the interproximal reinforcement 102 may include a substantially smooth and continuous arcuate shape after the interproximal region. The substantially smooth and continuous arcuate shape may result in substantially uniform (e.g., uniform or near-uniform) stiffness characteristics of the interproximal reinforcement 102. In some embodiments, the interproximal reinforcement 102 may include a serpentine or zigzag shape extending along the interproximal region having two or more linear segments joined at an angle. Forming the interproximal reinforcement 102 with a curved shape, for example, a serpentine or zigzag shape, may result in more controllable and appropriate engagement force levels and directions during dental treatment intervals.

[0044] The cross-sectional shape of the interproximal reinforcement 102 may be substantially constant or may vary along the length of the interproximal reinforcement 102. The cross-sectional shape may include, for example, an oval, a rectangle, other geometric shapes, or an irregular shape. In some embodiments, the cross-section of each interproximal reinforcement of the interproximal reinforcement 102 may be configured to control deformation of the respective interproximal reinforcement, thereby controlling the magnitude and direction of the force vector applied to each of the teeth 106 when the removable dental appliance 100 is worn by a patient. For example, as shown in FIG. 1B , the interproximal reinforcement 102A may include a first region 140 having a relatively small cross-sectional area to increase the flexibility of the respective interproximal reinforcement near the region.

[0045] Additionally or alternatively, first region 140 may include other features that increase the flexibility of first region 140, such as a relatively flat cross-section, notches, a region of material with a low modulus of elasticity, etc. The relative flexibility of each interproximal reinforcement near first region 140 may reduce the restorative forces exerted by interproximal reinforcement 102A when removable dental appliance 100 is worn by a patient. Similarly, interproximal reinforcement 102A may include second region 142 having a relatively large cross-sectional area to increase the stiffness of each interproximal reinforcement near first region 140.

[0046] Additionally or alternatively, the second region 142 may include other features that increase the stiffness of the second region 142, such as reinforcing ribs or rail areas of material with a higher modulus of elasticity. The second region 142 may be shaped to form a stepped or tapered joint on the exterior surface of the appliance body 104. The relative stiffness of each interproximal reinforcement 102A near the second region 142 may increase the restorative forces exerted by the interproximal reinforcement 102A when the removable dental appliance 100 is worn by a patient. Although the first region 140 and the second region 142 are shown near the exterior of the removable dental appliance 100, the regions of increased flexibility or stiffness may be located in any portion of each interproximal reinforcement 102. In this manner, selecting the shape of the interproximal reinforcements 102 can control the deformation of each interproximal reinforcement, thereby controlling the magnitude and direction of the force vector applied to each of the teeth 106 when the removable dental appliance 100 is worn by the patient.

[0047] The length of the interproximal reinforcement 102 may include any suitable length. In some embodiments, the length of the interproximal reinforcement 102 may affect the deformation of the interproximal reinforcement 102 and the resulting force on the tooth 106. For example, a longer interproximal reinforcement may result in a greater restorative force in the interproximal reinforcement 102, a longer distance over which the force is exerted in the interproximal reinforcement 102, or both, compared to a shorter interproximal reinforcement 102. In this manner, the length of each interproximal reinforcement of the interproximal reinforcement 102 may affect the force resulting from deformation of each interproximal reinforcement of the interproximal reinforcement 102 when the removable dental appliance 100 is worn by the patient.

[0048] In some embodiments, each interproximal reinforcement of interproximal reinforcement 102 may extend around less than the entire length of the respective interproximal region. For example, as shown in FIG. 1C , the lingual portion 144 of interproximal reinforcement 102B may extend from the occlusal portion 124 of the appliance body 104 near the occlusal surface 136 of tooth 106A to the lingual-gingival portion 116 of the appliance body 104 near the gingival margin of tooth 106. Additionally or alternatively, as shown in FIG. 1C , the labial portion 146 of interproximal reinforcement 102B may extend from the occlusal portion 124 of the appliance body 104 near the occlusal surface 136 of tooth 106A to the labial-gingival portion 110 of the appliance body 104 near the gingival margin of tooth 106. In some embodiments, each interproximal reinforcement of interproximal reinforcement 102 may extend a length substantially equal to the entire length of the interproximal region. For example, as shown in FIG. 1B, the interproximal reinforcement 102A may extend from a lingual gingival portion 116 of the appliance body 104 near the lingual gingival margin of the tooth 106 to a labial gingival portion 110 of the appliance body 104 near the labial gingival margin of the tooth 106.

[0049] In some embodiments, each interproximal reinforcement of the interproximal reinforcement 102 may include a length greater than the length of its respective interproximal region. For example, as shown in FIG. 1D , the interproximal reinforcement 102C may overhang a portion of the lingual gingival margin of the tooth 106B, a portion of the labial gingival margin of the tooth 106B, or both. By overhanging a portion of the gingival margin, the interproximal reinforcement 102C may be configured to anchor through the gingiva to at least a portion of the alveolar bone. For example, when worn by a patient, the interproximal reinforcement 102C may at least partially contact the gingiva overlying the alveolar process to effect at least a portion of the deformation of the interproximal reinforcement 102C. In this manner, the removable dental appliance 100 may be configured to utilize the alveolar process as an anchor. For example, the inclusion of one or more interproximal reinforcements 102 attached to one or more respective portions of the shell 108 that extend to contact the gums allows for access to additional braces provided by extension surfaces that indirectly engage the alveolar process without interfering with the mobility of the tooth 106, allowing for greater forces to be applied to selected ones of the teeth 106 while using the stiffer alveolar process as an anchor instead of the adjacent teeth 106 or both. Thus, another advantage can be better control of tooth movement relative to a fixed reference (alveolar process) without causing undesired reactive movement of the adjacent teeth 106.

[0050] The interproximal reinforcements 102 may comprise any suitable material. In some embodiments, each of the interproximal reinforcements 102 may comprise one or more continuous or discontinuous regions of material disposed on or integrally formed with the appliance body 104. In some embodiments, the interproximal reinforcements 102 and the appliance body 104 may be formed from a single material. The interproximal reinforcements 102 may be formed from a material with a relatively high modulus of elasticity compared to the appliance body 104. Forming the interproximal reinforcements 102 from a material with a higher modulus of elasticity may strengthen the appliance body in the interproximal region relative to the adjacent portion of the appliance body 104, increase the durability of the removable dental appliance 100, and / or improve control over the direction of forces applied to the shell 108. In some embodiments, each interproximal augmentation of interproximal augmentation elements 102 may comprise a metal wire, including, but not limited to, iron, copper, tin, nickel, titanium, molybdenum, tungsten, and alloys thereof, such as stainless steel (SS), nickel-titanium (NiTi or Nitinol), copper-nickel-titanium (CuNiTi), cobalt-chromium (CoCr), cobalt-chromium-molybdenum (CoCrMo), or cobalt-chromium-tungsten (CoCrW), etc. Metal wires include braided and non-braided wires and wires having any suitable cross-sectional shape, such as oval or rectangular. In some embodiments, each interproximal reinforcement of interproximal reinforcement 102 may include, but is not limited to, polylactic acid, epoxy, silicone, polyester, polyurethane, polycarbonate, thiol-ene polymer, urethane, (meth)acrylate polymer or acrylate polymer such as poly(methyl methacrylate), polyalkylene oxide di(meth)acrylate, alkanediol di(meth)acrylate, aliphatic (meth)acrylate, silicone (meth)acrylate, polyethylene terephthalate-based polymer such as polyethylene terephthalate glycol, polypropylene, ethylene-vinyl acetate, nylon, acetal resin (POM or Delrin®), acrylonitrile butadiene styrene, or combinations thereof.In some embodiments, the polymer ribs may comprise a polymer configured to be dispensed using a fused deposition modeling (FDM) printing process, such as a polymer suitable for robotically dispensing beads of polymer onto the surface of a removable dental appliance using a heated extrusion nozzle. The use of FDM printing may allow for control of the thickness of selected regions of the removable dental appliance, such as the interproximal reinforcement 102, or for control of material properties compared to the bulk material of the removable dental appliance. In embodiments in which both the polymer rib material and the removable dental appliance material comprise thermoplastic materials, the FDM-printed material may fuse to the removable dental appliance material.

[0051] The interproximal reinforcement 102 may be attached to the appliance body 104 using any suitable attachment means. The interproximal reinforcement 102 and / or each interproximal reinforcement of the appliance body 104 may be shaped to form a graduated or tapered joint when the respective interproximal reinforcement is attached to the appliance body 104. In some embodiments, the interproximal reinforcement 102 may be integrally formed with the appliance body 104. For example, the removable dental appliance 100 may comprise a unitary polymer that includes the appliance body 104 and the interproximal reinforcement 102. In some embodiments, the interproximal reinforcement 102 may be physically separate from and mechanically attached to the appliance body 104 along one or more portions of the interproximal reinforcement 102. In some embodiments, each interproximal augmentation member 102 may be adhered to the appliance body 104 along the entire length of the respective interproximal augmentation member, along a portion of the respective interproximal augmentation member, or along two or more discontinuous portions of the respective interproximal augmentation member. Suitable adhesives may include, for example, epoxy resins, polyurethanes, cyanoacrylates, and the like. In some embodiments, each interproximal augmentation member or interproximal augmentation member 102 may be at least partially surrounded by two or more layers of material forming the appliance body 104. For example, the interproximal augmentation member 102 may be formed or disposed on a first layer of material of the appliance body 104, and a second layer of material of the appliance body 104 may be formed or disposed on the first layer of material and the interproximal augmentation member 102.

[0052] In some embodiments, the appliance body 104 may define one or more alignment guides configured to mechanically attach each interproximal augmentation of the interproximal augmentation members 102 to the appliance body 104. For example, as shown in FIG. 1E , the appliance body 104 may define alignment guide 148. Alignment guide 148 may be integrally formed with the appliance body 104 in the interproximal region 114 between shells 108D and 108E. Alignment guide 148 may be configured to receive each interproximal augmentation member of interproximal augmentation members 102 (e.g., interproximal augmentation member 102B). For example, alignment guide 148 may be shaped to engage each interproximal augmentation member of interproximal augmentation members 102 in a push-fit or push-connect arrangement. As an example, the alignment guide 148 may include recesses shaped to receive the shape of each interproximal augmentation element of the interproximal augmentation elements 102 and one or more ridges or posts integrally formed with the appliance body 104. The appliance body 104, such as the one or more ridges or posts, may deform when each interproximal augmentation element of the interproximal augmentation elements 102 is inserted (e.g., pushed) into the recess, allowing the respective interproximal augmentation element to seat within the recess. The one or more ridges or posts may then return to an undeformed configuration to retain the respective interproximal augmentation element within the recess. In some embodiments, the interproximal augmentation elements 102 may be attached to the appliance body 104 using a combination of mechanical attachments. In some embodiments, a first portion of each interproximal augmentation member 102 may be secured to the appliance body 104, and a second portion of each interproximal augmentation member may be secured within an elongated recess but be free to move in a selected direction, such as by moving along the longitudinal axis of the elongated recess. By securing selected portions of the interproximal augmentation member 102 to the appliance body 104, the removable dental appliance 100 may control the location at which restorative forces on the interproximal augmentation member 102 are transmitted to the appliance body 104, while other portions of the interproximal augmentation member 102 are free to move in a selected direction.For example, in embodiments in which the interproximal reinforcement 102 is secured to the appliance body 104 near the gingival portions 110 and 116, restorative forces from deformation of the interproximal reinforcement 102 can be substantially transmitted to contact points near the gingival margins of the teeth 106. Force transmission through engagement near the gingival margins of the teeth 106 can enable or enhance desired tooth movements, such as rotation, torquing, chipping, or extrusion. In this manner, selecting the type and location of attachments on the interproximal reinforcement 102 or appliance body 104 can affect the magnitude and / or force vector applied to the teeth 106 when the removable dental appliance 100 is worn by a patient.

[0053] By selecting the material, shape, length, and attachment of each interproximal reinforcement of the interproximal reinforcement 102, the removable dental appliance 100 can control at least one of the direction, magnitude, and length of the force exerted on each shell of the shells 108 resulting from deformation of the appliance body 104 when the removable dental appliance 100 is worn by a patient.

[0054] In some examples, the appliance body 104 may be formed from a single material, such as a single, monolithic material. The monolithic material may include a single polymer or a substantially homogeneous mixture of one or more polymers. For example, the removable dental appliance 100 may be comprised of a single, continuous 3D-printed or thermoformed component. In other examples, the appliance body 104 may include a multilayer material. The multilayer material may include a single material, such as a single polymer, multiple layers of multiple materials, such as two or more polymers, or multiple layers of a polymer and another material. A multilayer material may allow one or more portions of the appliance body 104 to be formed with multiple layers having different elastic moduli, allowing for selection of the force characteristics, displacement characteristics, or both of the interproximal reinforcement 102. For example, the removable dental appliance 100 may be comprised of a multilayer 3D-printed or thermoformed component. Suitable polymers can include, but are not limited to, (meth)acrylate polymers, epoxies, silicones, polyesters, polyurethanes, polycarbonates, thiol-ene polymers, urethane (meth)acrylate polymers, polyalkylene oxide di(meth)acrylates, alkanediol di(meth)acrylates, aliphatic (meth)acrylates, acrylate polymers such as silicone (meth)acrylates, polyethylene terephthalate-based polymers such as polyethylene terephthalate glycol (PETG), polypropylene, ethylene-vinyl acetate, or combinations thereof. In the same or a different embodiment, the removable dental appliance 100 can include chamfers or fillets on the edges and other spaces of the appliance body 104. Such chamfers or fillets can improve patient comfort and reduce the visibility of the removable dental appliance 100.

[0055] In other embodiments, the removable dental appliance 100 may include a metal component configured to enhance the force applied to one or more of the teeth 106 surrounded by the removable dental appliance 100. For example, the metal component may include a wire or ribbon extending through at least a portion of the appliance body 104, such as the interproximal reinforcement 102. In some embodiments, the removable dental appliance 100 may include one or more other metal components, such as metal occlusal components, if greater durability is required to overcome the stresses of high-pressure occlusal contacts, such as bruxism or chewing. In some embodiments, the removable dental appliance 100 may include a catch configured to engage a fixation device implanted within the patient, such as a temporary fixation device or miniscrew, or an attachment secured to the tooth surface of the tooth 106. For example, the catch may be disposed on the anchor shells 108A-104D and 104K-104N and connected to the anchor device on the anchor teeth 106A-103D and 103K-103N. In this manner, such removable dental appliances 100 may provide a hybrid metal and plastic construction.

[0056] In some examples, metal components may be formed on the removable dental appliance 100 using an electroforming (or electrodeposition) process. For example, a conductive coating may be applied to selected areas of the removable dental appliance 100 by electroless plating, physical vapor deposition (e.g., electron beam physical vapor deposition, evaporation, sputter deposition, etc.), or conductive paint. The selected areas may be masked before depositing the conductive coating to ensure that only the selected areas are conductive. After applying the conductive coating, one or more contact points on the conductive coating may be connected to a first terminal of a power source, e.g., the negative terminal of a direct current voltage source, and the donor metal piece may be connected to a second terminal of the power source, e.g., the positive terminal of the direct current voltage source. The removable dental appliance may then be immersed in an electrolyte solution, such as water, salt water, or acid. The current applied to the terminals may result in the migration of metal ions from the donor metal through the solution to the conductive surface of the device to be deposited. The duration of the electroplating may be controlled to control the thickness of the metal coating. In some embodiments, masking may include placing non-conductive vertical dams on either side of the conductive region to control the shape of the deposited metal, for example, to make the sidewalls of the deposited metal perpendicular to the substrate surface. In some embodiments, the dams may function to reinforce the metal reinforcement, hold it in place under stress, and minimize the possibility of separation. In some embodiments, the dams may include a fillet between the vertical wall of the metal reinforcement and the horizontal surface of the substrate to relieve mechanical stress at the joint and / or increase patient comfort. In some embodiments, a metal with suitable structural properties and ease of electroforming, such as nickel, may be used for the bulk of the deposited metal. To improve biocompatibility (e.g., to reduce the possibility of allergic reactions or corrosion), the bulk metal may be coated with one or more inert metals, metal oxides, or polymers, such as gold, platinum, or rhodium. Additionally or alternatively, the entire exterior surface of the removable dental appliance may be coated with another layer of polymer or thermoformable polymer sheet.

[0057] The plastic components may be substantially clear to reduce visibility, while the metal components may include plating or other coloring agents to reduce the visibility of the removable dental appliance 100 when worn by a patient. For example, metal components that are positioned near the patient's teeth 106 when worn may include a white coating or plating, such as rhodium, silver, white anodized titanium, Teflon, PTFE, or may be formed of a white metal, such as rhodium, silver, white anodized titanium, etc. Metal components positioned elsewhere may be colored to generally match the color of tissue in the patient's mouth.

[0058] FIG. 2 is a block diagram illustrating an exemplary computer environment 10 in which a clinic 14 and a manufacturing facility 20 communicate information throughout the manufacturing process of a set of removable dental appliances 22 for a patient 12. The set of removable dental appliances 22 may include removable dental appliances 100. As described above, the removable dental appliances 100 include at least two shells and at least one interproximal reinforcement. Initially, an orthodontist at the clinic 14 generates one or more images of the patient's 12's dental structure using any suitable imaging technology to generate digital dental structure data 46 (e.g., a digital representation of the patient's 12's tooth structure). For example, the orthodontist may generate x-ray images that can be digitally scanned. Alternatively, the orthodontist may capture digital images of the patient's tooth structure using, for example, conventional computed tomography (CT), laser scanning, intraoral scanning, CT scanning of dental impressions, scanning of dental casts poured from the impressions, ultrasound measurement, magnetic resonance imaging (MRI), or any other suitable method of three-dimensional (3D) data acquisition. In other embodiments, the digital images may be provided using a handheld intraoral scanner, such as the intraoral scanner using active wavefront sampling developed by Brontes Technologies, Inc. (Lexington, Massachusetts) and described in PCT Publication No. WO 2007 / 084727 (Boerjes et al.). Alternatively, other intraoral scanners or intraoral contact probes may be used. Alternatively, digital dental structure data 16 may be provided by scanning negative impressions of the patient's 12 teeth. As yet another option, digital dental structure data 16 may be provided by imaging a positive physical model of the patient's 12 teeth or by using a contact probe on a model of the patient's 12 teeth. The model used for scanning may be made, for example, by casting an impression of the patient's 12 dentition from a suitable impression material such as alginate or polyvinylsiloxane (PVS), pouring a casting material (such as orthodontic stone or epoxy resin) into the impression, and allowing the casting material to harden.Any suitable scanning technique may be used to scan the model, including those described above. Other possible scanning methods are described, for example, in U.S. Patent No. 9,191,648 (Kriveshko et al.) and U.S. Patent No. 9,245,374 (McQueston et al.).

[0059] In addition to providing digital images by scanning exposed tooth surfaces, it is possible to image non-visible features of the dentition, such as the roots of the patient's 12 teeth and the patient's 12 jawbone. In some embodiments, digital dental structure data 16 is formed by preparing several 3D images of these features and then "stitching" them together. These different images need not be provided using the same imaging technology. For example, a digital image of the roots provided by a CT scan may be integrated with a digital image of the crowns provided by an intraoral visible light scanner. Scaling and registration of two-dimensional (2D) dental images with 3D dental images is described in U.S. Patent No. 6,845,175 (Kopelman et al.). Issued U.S. Patent Nos. 7,027,642 (Imgrund et al.) and 7,234,937 (Sachdeva et al.) describe the use of techniques to integrate digital images provided from various 3D sources. Thus, the term "imaging," as used herein, is not limited to conventional photographic imaging of visually apparent structures, but also includes imaging of dental structures hidden from view, which may include, but are not limited to, any portion of one or more crowns or roots of a dental arch, gums, periodontal ligament, alveolar bone, cortical bone, implants, artificial crowns, bridges, veneers, dentures, orthodontic appliances, or any structure that may be considered part of the dentition before, during, or after treatment.

[0060] To generate digital dental structure data 16, a computer must convert the raw data from the imaging system into a usable digital model. For example, when a computer receives raw data representing tooth shapes, the raw data is often simply a cloud of points in 3D space. Typically, this point cloud is organized into a surface to create a 3D object model of the patient's dentition, including one or more teeth, gum tissue, and other surrounding oral structures. To make this data useful in orthodontic diagnosis and treatment, the computer may "segment" the dentition surface and generate one or more separate, movable 3D tooth object models representing each tooth. The computer may further separate these tooth models from the gums into separate objects.

[0061] Segmentation allows the user to characterize and manipulate the tooth arrangement as a set of individual objects. Advantageously, a computer can derive diagnostic information from these models, such as arch length, bite alignment, spacing between adjacent teeth, and even American Board of Orthodontics (ABO) grading. As an additional benefit, digital orthodontic setup may provide flexibility to the manufacturing process. By replacing physical processes with digital processes, data acquisition and data manipulation steps can be performed in separate locations, without the need to transport stone models or impressions from one location to another. Reducing or eliminating the need to transport physical objects back and forth can result in significant cost savings for both the customer and the manufacturer of customized appliances.

[0062] After generating the digital dental structure data 16, the clinic 14 may store the digital dental structure data 16 in a patient record in a database. The clinic 14 may, for example, update a local database having multiple patient records. Alternatively, the clinic 14 may remotely update a central database (optionally within the manufacturing facility 20) via the network 24. After storing the digital dental structure data 16, the clinic 14 electronically communicates the digital dental structure data 16 to the manufacturing facility 20. Alternatively, the manufacturing facility 20 may retrieve the digital dental structure data 16 from the central database. Alternatively, the manufacturing facility 20 may retrieve existing digital dental structure data 16 from a data source independent of the clinic 14.

[0063] The clinic 14 may also transmit prescription data 18 to the manufacturing facility 20, which conveys general information regarding the orthodontist's diagnosis and treatment plan for the patient 12. In some examples, the prescription data 18 may be more specific. For example, the digital dental structure data 16 may be a digital representation of the dental structure of the patient 12. The orthodontist at the clinic 14 may review the digital representation and indicate at least one of the desired movement, spacing, and final position of the patient's 12's individual teeth. For example, the desired movement, spacing, and final position of the patient's 12's individual teeth may affect the forces to be applied to the patient's 12's teeth by each removable dental appliance in the set of removable dental appliances 22 at each stage of treatment. As described above, the forces applied by each removable dental appliance 100 in the set of removable dental appliances 22 may be determined by selecting the size, shape, and position of the interproximal reinforcements (e.g., interproximal reinforcement 102) and shells (e.g., first and second shells 108). At least one of the desired movement, spacing, or final position of individual teeth of patient 12 enables one or more of the orthodontist, a technician at manufacturing facility 20, and a computer at manufacturing facility 20 to determine at least one of the selected dimensions, shapes, and positions of at least one of the shells and interproximal reinforcements. In this manner, digital dental structure data 16 may include at least one of the orthodontist, technician, or computer-selected dimensions, shapes, and positions of at least one of the interproximal reinforcements and shells of each removable dental appliance of the set of removable dental appliances 22 to effect the desired movement of the teeth of patient 12. After reviewing the digital representation, digital dental structure data 16, including the selected dimensions, shapes, and positions of the interproximal reinforcements and shells of each removable dental appliance of the set of removable dental appliances 22, can be transferred to manufacturing facility 20. Manufacturing facility 20 may be located elsewhere or may be associated with clinic 14.

[0064] For example, each clinic 14 may function as a manufacturing facility 20, allowing treatment planning and digital design to be performed entirely by a clinician or assistant using locally installed software in a clinical environment. Manufacturing may also occur within the clinic through the use of a 3D printer (or other methods of additive manufacturing). The 3D printer enables the fabrication of complex features of dental appliances or physical representations of the patient's 12 dental structure through additive manufacturing. The 3D printer may use iterative digital designs of the patient's 12's natural dental structure and the patient's 12's desired dental structure to create multiple digital appliances and / or digital appliance patterns customized to create the patient's 12's desired dental structure. In some examples, other methods of additive manufacturing may include, for example, thermoforming, 3D printing, and / or fused deposition modeling, using, for example, a 5-axis or 6-axis Cartesian robot or an articulated arm robot, to mill the removable dental appliance and then dispense material onto the surface of the removable dental appliance. Fabrication may include post-processing such as milling to remove uncured resin, remove support structures, or assemble various parts, which may also be necessary and could be performed in a clinical environment.

[0065] The manufacturing facility 20 uses the digital dental structure data 16 of the patient 12 to construct a set of removable dental appliances 22 for repositioning the patient 12's teeth. After some time has passed, the manufacturing facility 20 sends the set of removable dental appliances 22 to the clinic 14, or alternatively, directly to the patient 12. For example, the set of removable dental appliances 22 may be an ordered set of removable dental appliances. The patient 12 then wears the removable dental appliances 22 in the set of removable dental appliances 22 sequentially over time according to a predetermined schedule to reposition the patient 12's teeth. For example, the patient 12 may wear each removable dental appliance in the set of removable dental appliances 22 for a period of about one week to about six weeks, such as about two weeks to about four weeks or about three weeks. Optionally, the patient 12 may return to the clinic 14 for periodic monitoring of the progress of treatment with the removable dental appliances 22.

[0066] During such periodic observations, the clinician may arrange for the patient 12 to wear the removable dental appliances 22 in succession over time. The observations generally include a visual inspection of the patient's 12's teeth and may also include imaging to generate digital dental structure data. In some relatively uncommon circumstances, the clinician may decide to discontinue treatment of the patient 12 with the set of removable dental appliances 22, for example, by sending the newly generated digital dental structure data 16 to the manufacturing facility 20 to create a new set of removable dental appliances 22. In the same or a different example, the clinician may send the newly generated digital dental structure data 16 to the manufacturing facility 20 after completing the predetermined schedule of treatment with the removable dental appliances 22. Additionally, after completing the predetermined schedule of treatment with the removable dental appliances 22, the clinician may request a new set of removable dental appliances from the manufacturing facility 20 and continue treating the patient 12.

[0067] 3 is a flow diagram illustrating an exemplary process for generating digital dental structure data 16, as described above with reference to FIG. 2. Initially, an orthodontist collects patient personal and other information from patient 12 at clinic 14 and creates a patient record (32). As described, the patient record may be located within clinic 14 and, optionally, may be configured to share data with a database within manufacturing facility 20. Alternatively, the patient record may be located in a database at manufacturing facility 20 that is remotely accessible to clinic 14 via network 24, or in a database that is remotely accessible by both manufacturing facility 20 and clinic 14.

[0068] Digital dental structure data 16 for patient 12 may then be generated (34) using any suitable technique to create the virtual dental structure. Digital dental structure data 16 may include two-dimensional (2D) images and / or three-dimensional (3D) representations of the dental structure.

[0069] In one example, the 3D representation of the dental structure is generated using a cone beam computerized tomography (CBCT) scanner, such as the i-CAT 3D dental imaging device (available from Imaging Sciences International, LLC, 1910 N Penn Road, Hatfield, PA). The clinic 14 stores the 3D digital dental structure data 16 (in the form of radiographic images) generated by the CBCT scanner in a database located within the clinic 14 or, alternatively, within a manufacturing facility 20. A computing system processes the digital dental structure data 16 from the CBCT scanner, which may be in the form of multiple slices, and computes a digital representation of the tooth structure that can be manipulated within a 3D modeling environment.

[0070] If 2D radiographic images are used (36), the orthodontist may further generate 3D digital data (38). The 3D digital dental structure data 16 may be generated, for example, by making a physical impression or cast of the patient's 12 tooth structure and then digitally scanning it. For example, a physical impression or cast of the patient's 12 dental arch may be scanned using a visible light scanner, such as an OM-3R scanner (available from Laser Design, Inc., Minneapolis, Minnesota) or an ATOS scanner (available from GOM GmbH, Braunschweig, Germany). Alternatively, the orthodontist may generate the occlusal 3D digital dental structure data 16 by using an intraoral scan of the patient's 12 dental arch or existing 3D tooth data. For example, U.S. Patent No. 8,491,306, issued July 23, 2013, and entitled "REGISTERING PHYSICAL AND VIRTUAL TOOTH STRUCTURES WITH PEDESTALS," describes a method for creating digital scans from casts or registered impressions. Additionally, or alternatively, U.S. Patent No. 8,897,902, issued November 25, 2014, and entitled "ORTHODONTIC DIGITAL SETUPS," describes techniques for defining virtual tooth surfaces and virtual tooth coordinate systems. In either case, the digital data is digitally registered within a 3D modeling environment to create a composite digital representation of the tooth structure, which may include roots and occlusal surfaces.

[0071] In one embodiment, the 2D radiographic images and 3D digital data of the occlusal surfaces of the dental arch are registered by first attaching registration markers (e.g., fiducial markers or pedestals with known geometric dimensions) to the tooth structure of the patient 12 prior to generating both the radiographic images and the 3D digital scan. The digital representations of the registration markers in the 2D radiographic images and the 3D digital data may then be registered in a 3D modeling environment using registration techniques described in U.S. Pat. No. 8,491,306.

[0072] In another example, 3D digital data of tooth structure is generated by combining two 3D digital representations of tooth structure. For example, a first 3D digital representation may be a relatively low-resolution image of the root obtained from a CBCT scanner (e.g., an i-CAT 3D dental imaging device), and a second 3D digital representation may be a relatively high-resolution image of the crown obtained from an industrial CT scan of an impression of the patient's dental arch or a visible light (e.g., laser) scan of a cast. The 3D digital representations may be registered using a software program (e.g., Geomagic Studio software (available from 3D Systems, Inc., 333 Three D Systems Circle, Rock Hill, South Carolina)) that allows the 3D representations to be manipulated within a computer environment, or alternatively, the registration techniques described in U.S. Patent No. 8,491,306 may be used.

[0073] A computer system running 3D modeling software then renders a composite digital representation of the patient's dental arch, including the occlusal surfaces and root structure. The modeling software provides a user interface that allows the orthodontist to manipulate the digital representation of the teeth in 3D space relative to the digital representation of the patient's 12 dental arch. By interacting with the computer system, the orthodontist generates treatment information (40), such as by selecting representations of the final positions of the patient's 12's individual teeth, the duration or number of treatment phases, the direction or magnitude of forces on the patient's 12's teeth during the treatment phases, etc. For example, the final positions of the patient's 12's individual teeth, the duration or number of treatment phases, or the number of treatment phases can affect the direction or magnitude of forces on the patient's 12's teeth during each treatment phase with each removable dental appliance in the set of removable dental appliances 22. In some embodiments, interproximal reinforcements may be used during at least one of the treatment phases, but fewer than all of the treatment phases. As described above, the force applied by each removable dental appliance 100 of the set of removable dental appliances 22 can be determined by selecting the size, shape, and location of the interproximal reinforcement (e.g., interproximal reinforcement 102) and shell (e.g., shell 108). In this manner, updating the database with diagnostic and treatment information (40) can include determining or selecting, by a doctor, technician, or automatically by a computer, the size, shape, and location of the interproximal reinforcement and shell of each removable dental appliance of the set of removable dental appliances 22 to effect the desired movement of the patient's 12's teeth.

[0074] Once the orthodontist has completed communicating the general diagnosis and treatment plan information within the 3D environment, the computer system updates a database associated with the patient record and records prescription data 18 conveying the general diagnosis and treatment plan information specified by the orthodontist (42). Prescription data 18 is then relayed to manufacturing facility 20 so that manufacturing facility 20 can construct one or more removable dental appliances, including interproximal reinforcements, such as removable dental appliance 22 (44).

[0075] Although described with respect to an orthodontist located at an orthodontic clinic, one or more of the steps discussed with respect to Figure 3 may be performed by a remote user, such as a user located at manufacturing facility 20. For example, the orthodontist may simply transmit radiographic image data and a patient impression or cast to manufacturing facility 20, where the user interacts with a computer system to develop the treatment plan within the 3D modeling environment. Optionally, the digital representation of the treatment plan within the 3D modeling environment may then be transmitted to the orthodontist at clinic 14, who may review the treatment plan and either return his approval or indicate desired changes.

[0076] 4 is a block diagram illustrating an example of a client computing device 50 connected to manufacturing facility 20 via network 24 for generating digital dental data. In the illustrated example, client computing device 50 provides an operating environment for modeling software 52. Modeling software 52 presents a modeling environment for modeling and rendering 3D representations of patient 12's teeth. In the illustrated example, modeling software 52 includes a user interface 54, an alignment module 56, and a rendering engine 58.

[0077] The user interface 54 provides a graphical user interface (GUI) that visually displays a 3D representation of the teeth of the patient 12. In addition, the user interface 54 provides an interface for receiving input from the orthodontist 60, for example, via a keyboard and pointing device, touch screen, etc., to manipulate the teeth of the patient 12 within the modeled dental arch.

[0078] The modeling software 52 may be accessible to the manufacturing facility 20 via a network interface 70. The modeling software 52 interacts with a database 62 to access various data, such as treatment data 64, 3D data 66 related to the tooth structure of the patient 12, and patient data 68. The database 62 may be presented in various forms, including data storage files, lookup tables, or a database management system (DBMS) running on one or more database servers. The database management system may be a relational database management system (RDBMS), a hierarchical database management system (HDBMS), a multidimensional database management system (MDBMS), an object-oriented database management system (ODBMS or OODBMS), or an object-relational database management system (ORDBMS). The data may be stored in a single relational database, such as, for example, SQL Server from Microsoft Corporation. Although the database 62 is shown as local to the client computing device 50, it may be located remotely from the client computing device 50 and coupled to the client computing device 50 via a public or private network, such as the network 24.

[0079] Treatment data 64 represents diagnostic or repositioning information for the teeth of patient 12 selected by orthodontist 60 and placed within the 3D modeling environment. For example, treatment data 64 may include the size, shape, and position of interproximal reinforcements (e.g., interproximal reinforcement 102) and shells (e.g., shell 108), which may result in selected magnitudes and directions of force vectors applied to the patient's teeth (e.g., tooth 106) throughout the treatment plan.

[0080] Patient data 68 represents a group of one or more patients, such as patients 12, associated with orthodontist 60. For example, patient data 68 identifies general information about each patient 12, such as name, date of birth, and dental history.

[0081] The rendering engine 58 accesses and renders the 3D data 66 to generate a 3D view that is presented to the orthodontist 60 via the user interface 54. More specifically, the 3D data 66 includes information defining 3D objects representing each tooth (optionally including its root) and the jawbone within a 3D environment. The rendering engine 58 processes each object and renders a 3D triangular mesh within the 3D environment based on the viewpoint of the orthodontist 60. The user interface 54 displays the rendered 3D triangular mesh to the orthodontist 60 and allows the orthodontist 60 to change the viewpoint and manipulate the objects within the 3D environment.

[0082] U.S. Patent No. 8,194,067, issued June 5, 2012, entitled "PLANAR GUIDES TO VISUALLY AID ORTHODONTIC APPLIANCE PLACEMENT WITHIN A THREE-DIMENSIONAL (3D) ENVIRONMENT," and U.S. Patent No. 7,731,495, issued June 8, 2010, entitled "USER INTERFACE HAVING CROSS SECTION CONTROL TOOL FOR DIGITAL ORTHODONTICS," describe other examples of computer systems and 3D modeling software with user interfaces that can be used with the techniques described herein.

[0083] The client computing device 50 includes a processor 72 and a memory 74 for storing and executing the modeling software 52. The memory 74 may represent any volatile or non-volatile storage element. Examples include random access memory (RAM), such as synchronous dynamic random access memory (SDRAM), read-only memory (ROM), non-volatile random access memory (NVRAM), electrically erasable programmable read-only memory (EEPROM), and flash memory. Examples may also include non-volatile storage, such as hard disks, magnetic tape, magnetic or optical data storage media, compact discs (CDs), digital versatile discs (DVDs), Blu-ray discs, and holographic data storage media.

[0084] Processor 72 represents one or more processors, such as a general-purpose microprocessor, a specially designed processor, an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), a collection of discrete logic, or any type of processing device capable of performing the techniques described herein. In one example, memory 74 may store program instructions (e.g., software instructions) that are executed by processor 72 to perform the techniques described herein. In other examples, the techniques may be performed by specially programmed circuitry in processor 72. In these or other ways, processor 72 may be configured to perform the techniques described herein.

[0085] The client computing device 50 is configured to transmit the digital representation of the patient's 3D tooth structure, and optionally, the treatment data 64 and / or the patient data 68, to a computer 80 at the manufacturing facility 20 over the network 24. The computer 80 includes a user interface 82. The user interface 82 provides a GUI that visually displays the 3D representation of the digital tooth model. In addition, the user interface 82 provides an interface for receiving input from a user, for example, via a keyboard and pointing device, for manipulating the patient's teeth within the digital representation of the patient's 3D tooth structure.

[0086] The computer 80 may be further configured to automatically determine the size and shape of each removable dental appliance in the set of removable dental appliances 22. The size and shape of the removable dental appliances 22 may include the position, size, and shape of the shells and interproximal reinforcements such that the removable dental appliances 22 are configured to reposition one or more teeth from their initial positions to their final positions when the removable dental appliances are worn by a patient. As described above with reference to FIGS. 1A-1E, the position, size, and shape of the shells and interproximal reinforcements can affect the magnitude, direction, and length of force exertion applied to the teeth when the removable dental appliances are worn by a patient. For example, the thickness and shape of each interproximal reinforcement of the plurality of interproximal reinforcements can at least partially determine the magnitude, direction, and length of force exertion resulting from deformation of each interproximal reinforcement when the removable dental appliances are worn by a patient. The location at which each interproximal reinforcement is coupled to its respective shell can also at least partially determine the direction of force that may be transferred from each interproximal reinforcement to its respective shell. Additionally, the engagement position of each shell with each tooth determines the direction of the force applied to each tooth. The computer 80 may analyze at least one of the magnitude, direction, and length of the force exerted resulting from the deformation of each interproximal reinforcement when the removable dental appliance is worn by the patient to determine at least one of the position, size, and shape of each interproximal reinforcement that will result in the desired movement of the patient's teeth when the removable dental appliance is worn by the patient.

[0087] The computer 80 may present a representation of the removable dental appliances 22 for review by the user, including review of the size and shape. Alternatively, or in addition, the computer 80 may accept input from a user to determine the size and shape of the set of removable dental appliances 22 for the patient 12. For example, the user input may affect at least one of the automatically determined size or shape. The computer 80 may transmit or otherwise send the digital model of the set of removable dental appliances 22, the size and shape of the set of removable dental appliances 22, or both, to a computer-aided manufacturing system 84 for manufacturing the set of removable dental appliances 22.

[0088] The client computing device 50 and the computer 80 are merely conceptual representations of an exemplary computer system. In some embodiments, the functionality described with respect to the client computing device 50, the computer 80, or both may be combined on a single computing device or distributed among multiple computing devices within a computer system. For example, cloud computing may be used for the digital design of dental appliances described herein. In one example, a digital representation of tooth structure is received on one computer at a clinic, while the shape and dimensions of the removable dental appliance are determined using a different computer, such as the computer 80. In addition, the different computer, such as the computer 80, may not need to receive all of the same data for determining the shape and dimensions. The shape and dimensions may be determined, at least in part, based on knowledge gained through analysis of virtual models of historical or exemplary cases without receiving a complete 3D representation of the subject case. In such an example, the data transmitted between the client computing device 50 and the computer 80, or otherwise utilized to design the customized dental appliance, may be significantly smaller than the complete data set representing the patient's complete digital dental model.

[0089] FIG. 5 is a block diagram illustrating an example computer-aided manufacturing system 700 for construction of a removable dental appliance 722. In some embodiments, the computer-aided manufacturing system 700 may include a 3D printer, a fused deposition modeling device, or the like. The computer-aided manufacturing system 700 may include an additive manufacturing (AM) manufacturing system 702 in communication with a computer 704 and coupled to a build material source 710. In some embodiments, the computer-aided manufacturing system 700 may include the computer-aided manufacturing system 84 of FIG. 4. For example, the computer 704 may be the same as or substantially similar to the computer 80. The build material source 710 may include a source of at least one polymeric material, such as at least one of the polymeric materials of the appliance body 104 described above. The dental appliance 722 may be the same as or substantially similar to the removable dental appliance 100. In some embodiments, the dental appliance 722 may include one dental appliance of the set of dental appliances 22.

[0090] The additive manufacturing system 702 may include a movable platform 708 and an extrusion head 706. The movable platform 708 and the extrusion head 706 may be configured to manufacture a dental appliance 722. For example, the computer 704 may control the extrusion head 706 and the movable platform 708 to manufacture a removable dental appliance 722. Controlling the extrusion head 706 by the computer 704 may include at least one of controlling a material feed rate from a build material source 710 to the extrusion head 706, controlling a deposition rate of the build material on the dental appliance 722, controlling a temperature of the extrusion head 706, and controlling a position of the extrusion head 706. By controlling at least one of the material feed rate, the material deposition rate, the temperature of the extrusion head 706, and the position of the extrusion head 710, the computer 704 can control the manufacture of a position, size, and shape of at least a portion of the dental appliance 722. Controlling the movable platform 708 by the computer 704 can include at least one of controlling the translation of the movable platform in a plane perpendicular to the direction of material deposition from the extrusion head 706 and controlling the elevation of the movable platform along an axis substantially parallel to the direction of material deposition from the extrusion head 706. By controlling at least one of the translation and elevation of the movable platform 708, the computer 704 can control the fabrication of the position, size, and shape of at least a portion of the dental appliance 722.

[0091] 5 illustrates a computer-aided manufacturing system 700 configured for fused deposition modeling (FDM), but the computer-aided manufacturing system 700 may also be configured for stereolithography (SLA), reverse bath polymerization additive manufacturing, inkjet / polyjet additive manufacturing, or other methods of additive manufacturing. In embodiments where the computer-aided manufacturing system 700 is configured for polyjet printing, the computer-aided manufacturing system 700 may be configured to print multiple materials in a single print, thereby enabling a high modulus material for rigid components of the dental appliance 722 (e.g., the interproximal augmentation element 102) and a low modulus or elastomeric material for less rigid components of the dental appliance 722 (e.g., the shell 108). Furthermore, with polyjet additive manufacturing, the modulus of elasticity can be selectively varied across the dental appliance 722, for example, a different modulus of elasticity can be used for the interproximal augmentation element than for the shell, different portions of the interproximal augmentation element, or different portions of the shell. Similarly, a different modulus of elasticity may be used for the fixed shell than that used for the shells used to reposition the individual teeth.

[0092] 6A-6C are flow diagrams illustrating a process 500 performed at a manufacturing facility 20 for constructing a set of removable dental appliances 22. In some examples, the set of removable dental appliances 22 may include removable dental appliances 100. A computer 80 at the manufacturing facility 20 receives (502) digital dental structure data 16 and prescription data 18 from a clinic 14, including the initial positions of one or more teeth of the patient. Alternatively, the computer 80 may retrieve the information from a database residing within or otherwise accessible by the computer 80. If the clinic 14 has not already done so, a trained user associated with the computer 80 may interact with a computerized modeling environment running on the computer 80 to develop a treatment plan for a digital representation of the patient's tooth structure and generate prescription data 18. In other examples, the computer 80 may automatically develop a treatment plan based solely on the patient's tooth structure and predetermined design constraints.

[0093] Once the computer 80 receives the patient's tooth structure, the computer 80 determines (504) the size and shape of the patient's removable dental appliances. The size and shape of the removable dental appliances are configured to reposition one or more of the patient's teeth from their initial positions to their final positions when the removable dental appliances are worn by the patient. In the same or further embodiments, the computer 80 determines the size and shape of a set of the patient's removable dental appliances 22 configured to be worn sequentially.

[0094] In some embodiments, determining the size and shape of the removable dental appliance includes selecting, by the computer 80, the size and shape of the removable dental appliance according to a set of pre-defined design constraints. The set of pre-defined design constraints may include one or more factors, including, but not limited to, at least one of minimum and maximum local forces applied to one or more of the surrounded teeth, at least one of minimum and maximum rotational forces applied to one or more of the surrounded teeth, at least one of minimum and maximum translational forces applied to one or more of the surrounded teeth, at least one of minimum and maximum resultant forces applied to one or more of the surrounded teeth, and at least one of minimum and maximum stress or strain applied to the removable dental appliance when the removable dental appliance is worn by a patient and the surrounded teeth are in their initial positions. A minimum amount of force must be applied to provide sufficient pressure against the periodontal ligament to cause bone remodeling and tooth movement.

[0095] When determining the size and shape of the removable dental appliances, the computer 80 may use finite element analysis (FEA) to analyze the forces on the patient's teeth and the removable dental appliances. For example, the computer 80 may apply FEA to a solid model of the patient's teeth as the modeled teeth move from their initial positions to their final positions, representing treatment including a set of ordered removable dental appliances. The computer 80 may use FEA to select appropriate removable dental appliances for applying desired forces to the teeth. In addition, the computer 80 may use a virtual articulator to determine contact points between the teeth throughout the movement of the modeled teeth during treatment. The computer 80 may further include occlusal contact forces, such as intercuspation forces, along with forces from the removable dental appliances in the FEA force analysis when designing the removable dental appliances in the set of ordered removable dental appliances. The computer 80 may further determine the order in which the teeth will be moved to optimize force application, reduce treatment time, improve patient comfort, etc.

[0096] In some examples, determining the size and shape of the removable dental appliance 100 includes selecting, by the computer 80, the thickness of the appliance body 104, such as the shells 108 and the interproximal augmentation members 102, to provide a rigidity suitable for repositioning one or more of the patient's teeth from their initial positions to their final positions when the removable dental appliance is worn by the patient. In some examples, the thickness of each of the shells 108 may range from about 0.1 millimeters to about 2.0 millimeters, e.g., from about 0.25 millimeters to about 1.0 millimeters, or about 0.5 millimeters, while the thickness of the interproximal augmentation members 102 may range from about 0.05 millimeters to about 2.0 millimeters, or from about 0.1 millimeters to about 1.0 millimeters, or from about 0.25 millimeters to about 0.75 millimeters, or about 0.5 millimeters. In some examples, the computer 80 may further select materials for the removable dental appliance, such as those described above with respect to the removable dental appliance 100, according to predetermined design constraints.

[0097] The size and shape of the patient's removable dental appliance may be presented to the user via the user interface 82 of the computer 80 (506). In embodiments where the size and shape of the removable dental appliance are presented to the user via the user interface 82 of the computer 80, the user may have the opportunity to adjust design constraints or directly adjust the size and shape of the removable dental appliance before the design data is sent to the computer-aided manufacturing system 84. In some embodiments, the size and shape of the removable dental appliance may be presented to the user directly by the computer 80 as the removable dental appliance is manufactured by the computer-aided manufacturing system 84. For example, the computer 80 can send a digital model of the removable dental appliance 100 to the computer-aided manufacturing system 84, which manufactures the removable dental appliance according to the digital model from the computer 80.

[0098] However, even in embodiments where the dimensions and shape of the patient's removable dental appliances can be presented to the user via the user interface of computer 80 82, after user approval, computer 80 sends (508) a digital model of the removable dental appliances to computer-aided manufacturing system 84, which then manufactures (510) the removable dental appliances 100 of the set of removable dental appliances 22 according to the digital model from computer 80. Manufacturing of the removable dental appliances 22 may include hybrid plastic and metal manufacturing techniques such as 3D printing, thermoforming, injection molding, lost-wax casting, five-axis milling, laser cutting, multi-axis robotic fused deposition modeling (FDM), snap-fitting and overmolding, or electroforming, as well as other manufacturing techniques.

[0099] In some examples, manufacturing (510) the removable dental appliance 100 includes 3D printing the removable dental appliance 100. FIG. 6B is a flow diagram illustrating a technique for 3D printing a removable dental appliance including interproximal reinforcements. As shown in FIG. 6B, 3D printing the removable dental appliance 100 includes preparing a 3D printer (512). In some embodiments, preparing the 3D printer may include selecting and installing (e.g., loading) one or more polymers, one or more bonding agents, or other materials to be printed by the 3D printer. In some embodiments, preparing the 3D printer may include creating a stage or form on which the 3D printer will build up material. Printing the removable dental appliance 100 also includes building up material (514). In some examples, the build-up material may include inserting material onto the surface of the removable dental appliance 100 (e.g., an interproximal reinforcement 102 comprising a metal wire or ribbon) and restarting the build-up of the material, and the computer-aided manufacturing system 84 may include a 3D printer. In some examples, 3D printing the removable dental appliance 100 may include post-processing to remove uncured resin, remove support structures, remove excess material, or assemble various components, such as bonding a pre-formed interproximal reinforcement 102 to the surface of the removable dental appliance 100 or dispensing or building the interproximal reinforcement 102 directly onto the surface of the removable dental appliance 100, and may also be performed in a clinical setting.

[0100] In some examples, manufacturing (510) the removable dental appliance 100 includes thermoforming the removable dental appliance 100. FIG. 6 is a flow diagram illustrating a technique for thermoforming a removable dental appliance including interproximal reinforcements. As shown in FIG. 6C, thermoforming the removable dental appliance 100 includes preparing (522) a 3D model of the patient's dentition. In some examples, the 3D model may include a plaster (stone) model or another representation of the patient's dentition, such as printed by a 3D printer. The 3D model may include one or more teeth in their final positions or one or more teeth in intermediate positions (e.g., between initial and final positions resulting from orthodontic treatment). In some embodiments, the 3D model may include raised surfaces to facilitate forming at least one of the shell and interproximal reinforcements within the thermoformed and trimmed appliance body. Thermoforming the removable dental appliance 100 includes thermoforming the appliance body 104 over the 3D model (524). In some embodiments, thermoforming includes placing a polymer sheet over the 3D model and heating the polymer sheet to substantially conform (e.g., fit or approximately fit) the shape of the 3D model. In some embodiments, thermoforming can use a vacuum to facilitate conformation of the heated polymer sheet to the 3D model. Thermoforming the removable dental appliance 100 includes trimming excess material from the client's body to form the shell and interproximal reinforcements (526). In some embodiments, trimming can be done manually or automated by CNC or robotic machinery, such as an end mill or laser cutter.

[0101] In some embodiments, both thermoforming and 3D printing may be used to form different portions of the appliance body. For example, the shell 108 may be formed by thermoforming as described above, while the interproximal reinforcement 102 may be formed by 3D printing on the thermoformed shell 108. In some examples, the techniques described with respect to FIGS. 6A-6C may be embodied in a computer-readable storage medium, such as the computer-readable storage medium of the computing device 50, the computer 80, or both. The computer-readable storage medium may store computer-executable instructions that, when executed, configure a processor to perform the techniques described with respect to FIGS. 6A-6C.

[0102] 6A-6B may be applied to the design and manufacture of each of the ordered sets of removable dental appliances 22. For example, each removable dental appliance in the ordered set of removable dental appliances 22 may be configured to incrementally reposition a patient's teeth. In this manner, the ordered set of removable dental appliances 22 may be configured to reposition a patient's teeth to a greater extent than any one of the removable dental appliances in the set of removable dental appliances 22. Such an ordered set of removable dental appliances 22 may be specifically configured to incrementally reposition one or more of a patient's teeth from their initial positions to their final positions as the removable dental appliances in the patient's ordered set of removable dental appliances 22 are sequentially worn by the patient.

[0103] 7 is a flow diagram 600 illustrating successive iterations of treatment using an ordered set of removable dental appliances configured to reposition one or more teeth of a patient. In some examples, the ordered set of removable dental appliances may include removable dental appliance 100.

[0104] Treatment begins with a first iteration of treatment (602). At the start of the first iteration of treatment, the patient's teeth are in initial tooth positions as indicated by detention state X (604). To facilitate the design of an ordered set of removable dental appliances, a scan of the patient's teeth is taken (606), for example, as described above with respect to FIG. 2. From the scan of the patient's teeth, a computer, for example, computing device 50, generates two different shapes and sizes for the removable dental appliances in the ordered set, a first setup X a 608A and second setup X b 608B. Exemplary techniques for creating a digital model of a patient's teeth are described in U.S. Patent No. 8,738,165 (Cinader et al.), issued May 27, 2014, entitled "METHODS OF PREPARING A VIRTUAL DENTITION MODEL AND FABRICATING A DENTAL RETAINER THEREFROM," which is incorporated herein by reference in its entirety. The computer determines the first setup X by first adjusting the digital model of the patient's teeth to create a model of the desired position of the patient's teeth after treatment. a 608A and second setup X b608B. The computer may then create the shapes and dimensions of the removable dental appliances in the ordered set based on the time and force required to move the patient's teeth from their initial positions to their desired positions. For example, the computer model may adjust the thickness, position, shape, and size of the shells and interproximal reinforcements of the removable dental appliances in the ordered set to generate the forces required to move the patient's teeth from their initial positions to their desired positions. The modeled forces applied by the removable dental appliances in the ordered set may further be based on the gradual positional movements of the patient's teeth during treatment. In this manner, the computer may design each of the removable dental appliances in the ordered set according to the expected forces applied to the teeth at the expected positions of the teeth during treatment when the removable dental appliances in the ordered set will be worn by the patient.

[0105] In some embodiments, at least one different removable dental appliance, such as three in a set of removable dental appliances, is included in a first setup X. a 608A and second setup X b 608B can be used to manufacture at least two removable dental appliances, such as six, in a set of removable dental appliances. For example, the first setup X a First aligner X using 608A a , Soft 610A, Second Aligner X a , intermediate 610B and third aligner X a , hard 610C and second setup X b Using 608B, the fourth aligner X b , Soft 610D, 5th Aligner X b , intermediate 610E and sixth aligner X bThe first, second, and third aligners 610A-610C may be substantially the same shape and size, but may comprise materials with different stiffness characteristics. For example, the second and third aligners 610B and 610C may have higher stiffness characteristics than the first aligner 610A, and the third aligner 610C may have higher stiffness characteristics than the second aligner 610B. Similarly, the fourth, fifth, and sixth aligners 610D-610F may be substantially the same shape and size, but may comprise materials with different stiffness characteristics. In some embodiments, the first aligner 610A may have the same stiffness characteristics as the fourth aligner 610D, such as a relatively soft polymeric material. Similarly, the second aligner 610B may have the same stiffness characteristics as the fifth aligner 610E, such as a polymer material that is relatively stiffer than the first aligner 610A. Similarly, the third aligner 610C may have the same stiffness characteristics as the sixth aligner 610F, such as a polymer material that is relatively stiffer than the second aligner 610B.

[0106] The aligners 610A-610F in the set of ordered removable dental appliances may be worn sequentially by the patient over an extended period of time. For example, each of the aligners 610A-610F in the set of ordered removable dental appliances may be worn for about one week to about six weeks, such as about two weeks to about four weeks, or about three weeks. After treatment planning using the aligners 610A-610F, the patient's teeth may be in their final positions in the first iteration of treatment, as indicated by detention state X+1 (612).

[0107] Once the patient's teeth are at or near dentition state X+1, the patient may return to the clinician, who may evaluate the results of the first iteration of treatment (614). If the first iteration of treatment resulted in acceptable final positions of the patient's teeth, treatment may be terminated (616). However, if the first iteration of treatment did not result in acceptable final positions of the patient's teeth, one or more additional iterations of treatment may be performed. To begin the next iteration of treatment, the clinician may again scan the patient's teeth to facilitate the design of the next set of ordered removable dental appliances (606). In some examples, evaluating the results of the first iteration of treatment may include again scanning the patient's teeth, in which case initiating the next iteration of treatment may simply include sending a digital model of the patient's teeth to a manufacturing facility so that another set of ordered removable dental appliances can be manufactured for the patient based on the new positions of the patient's teeth. In yet another example, the newly acquired scans may be used to create one or more iterations of removable dental appliances at the clinician's facility.

[0108] The technique of FIG. 7 illustrates one specific example, and various modifications may be made to the technique of FIG. 7 within the spirit and scope of the present disclosure. For example, the set of ordered removable dental appliances may include more or less than six removable dental appliances. As another example, each removable dental appliance in the set of ordered removable dental appliances may have a unique shape and size, and each removable dental appliance in the set of ordered removable dental appliances may be made of a material having substantially the same or similar rigidity characteristics. As another example, each removable dental appliance in the set of ordered removable dental appliances may include a selected thickness, width, height, length, shape, material, or presence of an interproximal reinforcement. For example, the first aligner X a , Soft 610A, Second Aligner X a , intermediate 610B and third aligner X a, the hard 610C may be the first thickness of the interproximal reinforcement, while the fourth aligner X b , Soft 610D, 5th Aligner X b , intermediate 610E and sixth aligner X b , rigid 610F may be a second, different thickness of interproximal reinforcement. The first thickness may be less than the second thickness. As another example, each removable dental appliance in the ordered set of removable dental appliances may include one or more interproximal reinforcement selected sizes, one or more interproximal reinforcement selected shapes, or both. [Example]

[0109] Tests were conducted to evaluate the effectiveness of interproximal braces and compare their performance with dental attachments. Figure 8 shows an experimental setup 900 for measuring the force applied to the roots of model first premolars by removable dental appliances. A removable dental appliance 902 was formed, including a copper wire as an interproximal brace attached to the appliance body in the interproximal space of the left first premolar and a pocket for receiving a dental attachment attached to the right first premolar. The removable dental appliance 902 was thermoformed from 0.75 mm thick Duran PET-G thermoplastic material. Three-dimensional models of the right first premolar (not shown) and left first premolar 904B (collectively, tooth model 904) were 3D printed and placed within the respective shells of the removable dental appliance 902. The removable dental appliance 902 was clamped to the angle brackets of the corresponding lateral incisors and first molars using clamps 906A and 906B. The occlusal surfaces of the removable dental appliance 902 were shaped to be held against the angle brackets without applying force or displacement to the labial and lingual surfaces of the removable dental appliance 902.

[0110] A Lloyd Instruments LF Plus Digital Testing Machine available from AMETEK Test & Calibration Instruments (Largo, Florida) ("Testing Machine 908") was used to apply force to the root of the tooth model. Typically, the maximum torque applied to a tooth during orthodontic treatment is approximately 10 Newton-millimeters (N-mm). For tooth model 904, the distance from the center of the labial tooth surface to the base of the root was approximately 17.0 mm. The maximum force applied to the base of the root was 10 N-mm / 17.0 mm = 0.59 N. Force was applied to the root of tooth model 904 in the mesial, distal, labial, and lingual directions. Five consecutive runs were performed for each test to measure the force applied to the root of tooth model 904 in the mesial, distal, labial, and lingual directions. The measured forces were averaged for each run. The first run of each test was excluded from the average due to slippage between the removable dental appliance 902 and the tooth model 904 during some tests. The second and subsequent runs were performed without resetting the tooth model 904 on the removable dental appliance 902.

[0111] 9-12 show the average measured force applied to the root of a tooth model 904 by a removable dental appliance 902 including an interproximal reinforcement on the left first premolar 904B ("Average Interproximal Reinforcement") and using an attachment on the model right first premolar 904A ("Average Attachment"). Displacement values ​​are relative to the point where the root of the tooth model 904 is first contacted by the first test tooth, so that the graph shows relative displacement, not absolute displacement, of the tooth model 904. FIG. 9 shows the measured force (kilograms, "kg") applied in the distal direction (e.g., "distal pressure") to the tooth model 904 versus the displacement (millimeters, "mm") of the removable dental appliance 902 using an attachment fixed to the model right first premolar 904A ("Attachment") and using an interproximal reinforcement including a wire on the model left first premolar 904B ("Wire IR"). FIG. 10 shows the measured force in the labial direction (e.g., "labial pressure") applied to the tooth model 904 versus the displacement (mm) of the removable dental appliance 902 using attachments and wire IR. FIG. 11 shows the measured force in the lingual direction (e.g., "lingual pressure") applied to the tooth model 904 versus the displacement (mm) of the removable dental appliance 902 using attachments and wire IR. FIG. 12 shows the measured force in the mesial direction (e.g., "mesial pressure") applied to the tooth model 904 versus the displacement (mm) of the removable dental appliance 902 using attachments and wire IR. As shown in FIGS. 9-12, the performance of the removable dental appliance with wire interproximal reinforcements (and without tooth attachments) is similar to the performance of the removable dental appliance with tooth attachments.

[0112] Tests were also conducted in which a rotational moment was applied to the tooth model 904. The removable dental appliance 902 was clamped to angle brackets on the lateral incisors and first molars, as described above. A testing machine 908 was used to apply a force to the end of a metal pin inserted into a hole in the tooth model 904. The moment was applied to the tooth model 904 in clockwise and counterclockwise directions. The resulting moment tended to rotate the tooth model 904. The ability of the interproximal reinforcement and attachment to resist the rotational moment was evaluated. The maximum torque typically applied to teeth during orthodontic treatment is approximately 10 N-mm. The distance from the central axis of the first premolar to the end of the metal pin was approximately 35.0 mm. The maximum force applied to the end of the metal pin was 10 N-mm / 35.0 mm = 0.28 N. The results of the moment applied to the tooth model 904 are shown in Figures 13 and 14. The angular rotations shown in Figures 13 and 14 have been corrected to remove the apparent rotational component caused by the elastic deformation of the metal pin. Figure 13 shows the measured force (e.g., moment, Newton-millimeters ("N-mm")) in the counterclockwise direction (e.g., "CCW") applied to the tooth model 904 versus the rotation (degrees, "deg") of the removable dental appliance 902 using the attachment and wire IR. Figure 14 shows the measured force (e.g., moment, N-mm) in the clockwise direction (e.g., "CW") applied to the tooth model 904 versus the rotation (degrees) of the removable dental appliance 902 using the attachment and wire IR. The results demonstrate the ability of the interproximal reinforcement to resist tooth rotation caused by a rotational moment applied to the tooth. Similar performance of the interproximal reinforcement and the tooth attachment representing the interproximal reinforcement may be effective as a tooth attachment in rotating malpositioned teeth toward a desired rotation angle.

[0113] This test was also performed on a removable dental appliance containing polymer ribs as interproximal reinforcement in the interproximal space of a left first premolar formed by stereolithography ("SLA IR"). Figures 15-18 show the average measured force applied to the root of a tooth model 904 by a removable dental appliance 902 containing interproximal reinforcement on the left first premolar 904B ("average interproximal reinforcement") and with an attachment on the model right first premolar 904A ("average attachment"). Displacement values ​​are relative to the point where the root of the tooth model 904 is first contacted by the first test, so that the graph shows relative displacement, not absolute displacement, of the tooth model 904. FIG. 15 shows the measured force (kilograms, "kg") applied in the distal direction (e.g., "distal pressure") to the tooth model 904 versus the displacement (millimeters, "mm") of the removable dental appliance 902 using an attachment secured to the model's right first bicuspid 904A ("attachment") and a polymer interproximal reinforcement applied by stereolithography (SLA) to the model's left first bicuspid 904B ("SLA IR"). FIG. 16 shows the measured force in the labial direction (e.g., "labial pressure") to the tooth model 904 versus the displacement (mm) of the removable dental appliance 902 using the attachment and SLA IR. FIG. 17 shows the measured force in the lingual direction (e.g., "lingual pressure") to the tooth model 904 versus the displacement (mm) of the removable dental appliance 902 using the attachment and SLA IR. Figure 18 shows the measured force in the mesial direction (e.g., "mesial pressure") applied to the tooth model 904 versus the displacement (mm) of the removable dental appliance 902 using attachments and SLA IR. As shown in Figures 15-18, the performance of the removable dental appliance with SLA interproximal reinforcements (and without tooth attachments) is similar to the performance of the removable dental appliance with tooth attachments.

[0114] Tests were also conducted in which a rotational moment was applied to the tooth model 904 using an SLA IR as described above. The results of the moment applied to the tooth model 904 are shown in FIGS. 19 and 20. The angular rotations shown in FIGS. 19 and 20 have been corrected to remove the apparent rotational component caused by the elastic deformation of the metal pin. FIG. 19 shows the measured force (e.g., moment, Newton-millimeters (“N-mm”)) in the counterclockwise direction (e.g., “CCW”) applied to the tooth model 904 versus the rotation (degrees, “deg”) of the removable dental appliance 902 using the attachment and SLA IR. FIG. 20 shows the measured force (e.g., moment, N-mm) in the clockwise direction (e.g., “CW”) applied to the tooth model 904 versus the rotation (degrees) of the removable dental appliance 902 using the attachment and SLA IR. The results demonstrate the ability of the interproximal reinforcement to resist tooth rotation caused by a rotational moment applied to the tooth. The same performance of interproximal reinforcements and tooth attachments representing interproximal reinforcements can be effective as tooth attachments in rotating malpositioned teeth towards a desired angle of rotation.

[0115] Various embodiments have been described. These and other embodiments are within the scope of the following claims. List of embodiments: Embodiment 1 A removable dental appliance, comprising: An appliance body configured to at least partially encircle a plurality of teeth of a patient's dental arch, comprising: a first shell shaped to engage a first tooth of the plurality of teeth at an initial position of the first tooth; and an appliance body including a second shell shaped to engage a second tooth of the plurality of teeth at an initial position of the second tooth, the second tooth being adjacent to the first tooth; an interproximal reinforcement extending along the interproximal region between the first tooth and the second tooth from a first gingival margin of the appliance body on the labial side of the appliance body to a second gingival margin of the appliance body on the lingual side of the appliance body. A removable dental appliance, wherein the interproximal reinforcement is configured to engage at least one of a lingual surface of the first tooth below a contour height of the first tooth or a labial surface of the first tooth below a contour height of the first tooth, such that the appliance body applies a force vector at a contact point on the first tooth to enable movement of the first tooth toward a desired position of the first tooth when the removable dental appliance is worn by a patient. Embodiment 2 The removable dental appliance of embodiment 1, wherein the removable dental appliance comprises an alignment tray. Embodiment 3 A removable dental appliance according to embodiment 1 or 2, wherein the interproximal reinforcement causes the appliance body in the interproximal region to have a higher rigidity than the labial and lingual surfaces of the first shell. Embodiment 4 A removable dental appliance described in any one of embodiments 1 to 3, wherein the first shell includes a surface defining a void within the first shell, the surface being shaped to receive the first tooth in a desired position. Embodiment 5: A removable dental appliance according to embodiment 4, wherein the interproximal reinforcement is configured to engage the lingual surface of the first tooth and the labial surface of the first tooth to bias the occlusal portion of the surface of the first shell toward the occlusal surface of the first tooth. Embodiment 6: A removable dental appliance as described in embodiment 4, wherein the appliance body is configured to apply a force vector at a contact point on the first tooth opposite the portion of the void to move the first tooth toward the portion of the void. Embodiment 7 A removable dental appliance as described in embodiment 5 or 6, wherein the force vector is a first force vector, the contact point is a first contact point, the surface of the first shell further defines a second portion of the gap, and the appliance body is configured to apply a second force vector at the second contact point on the first tooth opposite the second portion of the gap to cause movement of the first tooth toward the second portion of the gap. Embodiment 8 The removable dental appliance of embodiment 7, wherein the first contact point and the second contact point are on opposite sides of the first tooth. Embodiment 9 The removable dental appliance of embodiment 7, wherein the first contact point is located near the occlusal surface of the first tooth and the second contact point is located near the gingival surface of the first tooth. Embodiment 10 The removable dental appliance of embodiment 7, wherein the first contact point is located on a lingual surface of the first tooth and the second contact point is located on a labial surface of the first tooth. Embodiment 11 The removable dental appliance of embodiment 7, wherein the first contact point and the second contact point are on the same side of the first tooth. Embodiment 12 A removable dental appliance described in any one of embodiments 1 to 11, wherein the interproximal reinforcement is biased toward the exterior of the appliance body near the occlusal surface of the appliance body and toward the interior of the appliance body at the first and second gingival margins to concentrate a force vector at the first tooth adjacent the gingival margin. Embodiment 13 The device body is a third shell shaped to engage a third tooth of the plurality of teeth at an initial position of the third tooth, the third tooth being adjacent to the first tooth; a second interproximal reinforcement extending along a second interproximal region between the first tooth and the third tooth from a first gingival margin on the labial side of the appliance body to a second gingival margin of the appliance body on the lingual side of the appliance body; A removable dental appliance according to any one of embodiments 1 to 12, wherein the second interproximal reinforcement is configured to engage with at least one of a lingual surface of the first tooth that is lower than the contour height of the first tooth or a labial surface of the first tooth that is lower than the contour height to apply a third force vector at a third contact point of the first tooth when the removable dental appliance is worn by a patient, thereby enabling the appliance body to apply a force vector at the contact point of the first tooth and move the first tooth toward the desired position of the first tooth. Embodiment 14 A removable dental appliance described in any one of embodiments 1 to 13, wherein the interproximal reinforcement comprises a metal wire or an integral polymer rib configured to strengthen the appliance body in the interproximal region relative to adjacent portions of the appliance body. Embodiment 15 A removable dental appliance described in any one of embodiments 1 to 14, wherein the cross-section of the interproximal reinforcement varies along the length of the interproximal reinforcement from the end adjacent to the first gingival margin to the end adjacent to the second gingival margin. Embodiment 16 A removable dental appliance described in any one of embodiments 1 to 15, wherein the appliance body defines an alignment guide including at least one recess, ridge, or post configured to receive an interproximal reinforcement. Embodiment 17 A removable dental appliance according to any one of embodiments 1 to 16, wherein the appliance body is thinner adjacent the first and second gingival margins than at the occlusal surface of the appliance body. Embodiment 18 A removable dental appliance described in any one of embodiments 1 to 17, wherein the appliance body does not include features configured to engage with a tooth attachment. Embodiment 19: A removable dental appliance according to any one of embodiments 1 to 17, wherein the appliance body further comprises a feature configured to engage with a tooth attachment. Embodiment 20. A system comprising an ordered set of removable dental appliances configured to reposition one or more teeth of a patient, wherein each removable dental appliance in the set of removable dental appliances comprises a removable dental appliance described in any one of embodiments 1 to 19.

[0023] Embodiment 21: Producing a model of a patient's dental structure that provides desired positions for a plurality of teeth; and forming a removable dental appliance based on the model, the removable dental appliance constituting the removable dental appliance of any one of embodiments 1 to 19. Embodiment 22. The method of embodiment 21, wherein forming the removable dental appliance comprises three-dimensionally printing or thermoforming the removable dental appliance and the interproximal reinforcement as a unitary piece. Embodiment 23. Forming a removable dental appliance comprises: 3D printing or thermoforming a removable dental appliance; forming an interproximal reinforcement separate from the removable dental appliance. Embodiment 24: The method of embodiment 23, wherein the removable dental appliance comprises an alignment guide configured to receive an interproximal reinforcement, the alignment guide comprising at least one recess, ridge, or post integrally formed with the appliance body, and the method further comprises inserting the interproximal reinforcement into the alignment guide. Embodiment 25. The method of embodiment 23 or 24, wherein forming the interproximal reinforcement includes at least one of bending and cutting a wire to define the interproximal reinforcement. Embodiment 26. The method of embodiment 23 or 24, wherein forming the interproximal reinforcement comprises extruding the interproximal reinforcement onto the appliance body. Embodiment 27. Receiving, by a computing device, a digital representation of a patient's three-dimensional dental structure, the dental structure providing initial positions for a plurality of teeth; determining, by a computing device, movement of a first tooth of the plurality of teeth from an initial position of the first tooth to a desired position of the first tooth; determining, by a computing device, a force vector applied to a contact point on the first tooth to effect the movement; determining, by a computing device, a removable dental appliance design including positions of interproximal reinforcements on the removable dental appliance to induce force vectors, the removable dental appliance including an appliance body configured to at least partially surround a plurality of teeth of the patient, the appliance body comprising: a first shell shaped to engage a first tooth of the plurality of teeth at an initial position of the first tooth; a second shell shaped to engage a second tooth of the plurality of teeth at an initial position of the second tooth, the second tooth being adjacent to the first tooth; and determining a dental appliance design including an interproximal augmentation extending along an interproximal region between a first tooth and a second tooth from a first gingival margin of the appliance body on a labial side of the appliance body to a second gingival margin of the appliance body on a lingual side of the appliance body, wherein the interproximal augmentation engages at least one of a lingual surface of the first tooth below a contour height of the first tooth or a labial surface of the first tooth below a contour height of the first tooth, and wherein the appliance body is configured to apply a force vector at a contact point of the first tooth to move the first tooth toward a desired position of the first tooth when the removable dental appliance is worn by a patient; transmitting, by a computing device, a representation of the removable dental appliance to a computer aided manufacturing system. Embodiment 28. The method of embodiment 27, wherein the movement comprises moving, rotating, or torquing the root. Embodiment 29. The method of embodiment 27 or 28, wherein determining the first tooth movement includes determining a plurality of movements, each movement of the plurality of movements corresponding to a respective movement of each of the plurality of teeth from an initial position of the respective tooth to a desired position of the respective tooth, and the method further includes ordering the plurality of movements by difficulty or length of occurrence to prioritize the plurality of movements. Embodiment 30. The method of any one of embodiments 27-29, wherein the removable dental appliance design further includes the size and shape of at least one of the first shell, the second shell, or the interproximal reinforcement. Embodiment 31: A method according to any one of embodiments 27 to 30, wherein determining the removable dental appliance design includes determining the position of an interproximal reinforcement on the appliance body and the size and shape of the interproximal reinforcement to reinforce the appliance body in the interproximal region against the labial and lingual surfaces of the first shell. Embodiment 32: The method of any one of embodiments 27 to 31, wherein determining the removable dental appliance design includes determining the dimensions and shape of a surface of a first shell, the surface defining a void within the first shell, and the surface being shaped to receive the first tooth in the desired position. Embodiment 33: The method of embodiment 32, wherein determining the removable dental appliance design includes determining the position of an interproximal reinforcement on the appliance body and the size and shape of the interproximal reinforcement to bias the surface toward the occlusal surface of the first tooth. Embodiment 34: The method of embodiment 32 or 33, wherein determining the removable dental appliance design includes determining the position of an interproximal reinforcement on the appliance body and the size and shape of the interproximal reinforcement to move the first tooth toward the first portion of the space. Embodiment 35: The method of any one of embodiments 32 to 34, wherein the force vector is a first force vector, the contact point is a first contact point, the surface of the first shell further defines a second portion of the space, and determining the removable dental appliance design includes determining the dimensions and shape of the first shell and the interproximal reinforcement, and applying a second force vector at a second contact point on the first tooth opposite the second portion of the space to move the first tooth toward the second portion of the space. Embodiment 36. The method of embodiment 35, wherein the first contact point and the second contact point are on opposite sides of the first tooth. Embodiment 37. The method of embodiment 35, wherein the first contact point is located near the occlusal surface of the first tooth and the second contact point is located near the gingival surface of the first tooth. Embodiment 38. The method of embodiment 35, wherein the first contact point is located on the lingual surface of the first tooth and the second contact point is located on the labial surface of the first tooth. Embodiment 39. The method of embodiment 35, wherein the first contact point and the second contact point are on the same side of the first tooth. Embodiment 40 The device body is a third shell shaped to engage a third tooth of the plurality of teeth at an initial position of the third tooth, the third tooth being adjacent to the first tooth; a second interproximal reinforcement extending along a second interproximal region between the first tooth and the third tooth from a first gingival margin on the labial side of the appliance body to a second gingival margin of the appliance body on the lingual side of the appliance body; The method of any one of embodiments 27 to 39, wherein the second interproximal reinforcement is configured to engage at least one of a lingual surface of the first tooth that is lower than the contour height of the first tooth or a labial surface of the first tooth that is lower than the contour height, and to apply a third force vector at a third contact point of the first tooth when the removable dental appliance is worn by a patient, thereby enabling the appliance body to apply a force vector at the contact point of the first tooth and move the first tooth toward the desired position of the first tooth. Embodiment 41: A method according to any one of embodiments 27 to 40, wherein determining the removable dental appliance design includes determining a material for an interproximal reinforcement to strengthen the appliance body in the interproximal region relative to the adjacent portion of the appliance body. Embodiment 42: A method according to any one of embodiments 27 to 41, wherein determining the removable dental appliance design includes determining the length and cross-section of an interproximal reinforcement, the cross-section varying along the length of the interproximal reinforcement from an end adjacent to the first gingival margin to an end adjacent to the second gingival margin. Embodiment 43: The method of any one of embodiments 27 to 42, wherein determining the removable dental appliance design includes determining the dimensions and shape of one or more features configured to engage with a dental attachment attachment. Embodiment 44 The method of any one of embodiments 27 to 43, wherein forming the removable dental appliance comprises three-dimensionally printing the removable dental appliance and the interproximal reinforcement as a unitary part. Embodiment 45. Forming a removable dental appliance comprises: 3D printing of removable dental appliances and 45. The method of any one of embodiments 27-44, comprising forming an adjacent reinforcement. Embodiment 46: The method of embodiment 45, wherein the removable dental appliance comprises an alignment guide configured to receive an interproximal reinforcement, the alignment guide comprising at least one recess, ridge, or post integrally formed with the appliance body, and the method further comprises inserting the interproximal reinforcement into the alignment guide. Embodiment 47. The method of embodiment 45 or 46, wherein forming the interproximal reinforcement includes at least one of bending and cutting a wire to define the interproximal reinforcement. Embodiment 48. The method of embodiment 45 or 46, wherein forming the interproximal reinforcement comprises extruding the interproximal reinforcement onto the appliance body. Embodiment 49. The method of any one of embodiments 27 to 48, wherein the patient's three-dimensional dental structure further comprises at least a portion of a tooth root, gingiva, periodontal ligament (PDL), alveolar bone, or cortical bone. Embodiment 50: A method according to any one of embodiments 27 to 49, wherein determining the removable dental appliance design includes accepting input from a user by a computing device, the input affecting at least one of dimensions and shape. Embodiment 51 A method according to any one of embodiments 27 to 50, wherein determining the removable dental appliance design includes automatically determining, by a computing device, at least one of the position of the interproximal reinforcement or the dimensions and shape of at least one of the first shell, the second shell and the interproximal reinforcement. Embodiment 52 A method according to any one of embodiments 27 to 51, wherein determining the removable dental appliance design includes presenting, by a computing device, a representation of the removable dental appliance to a user for review. Embodiment 53: A method according to any one of embodiments 27 to 52, wherein transmitting a representation of the removable dental appliance includes transmitting, by the computing device, a digital model of the removable dental appliance from the computing device to a computer-aided manufacturing system, and the method further includes manufacturing at least a portion of the removable dental appliance in the computer-aided manufacturing system according to the digital model. Embodiment 54 The method of embodiment 53, wherein the computer-aided manufacturing system includes a 3D printer, and at least a portion of the removable dental appliance is formed using the 3D printer. Embodiment 55 A method as described in any one of embodiments 27 to 54, further comprising determining by a computing device a removable dental appliance design for each of an ordered set of removable dental appliances for the patient, wherein the removable dental appliance is one of the ordered set of removable dental appliances for the patient, and each removable dental appliance in the ordered set of removable dental appliances is configured to progressively reposition at least one tooth of the plurality of teeth to a more advanced position than any one of the previous removable dental appliances in the set of removable dental appliances. Embodiment 56 The method of embodiment 55, wherein determining the movement of the first tooth includes determining a plurality of movements of the first tooth, the movements being respective movements of the plurality of movements corresponding to respective removable dental appliances of the ordered set of removable dental appliances. Embodiment 57. Determining by the computing device the size and shape of the removable dental appliance includes selecting by the computing device the size and shape of the removable dental appliance according to a set of predefined design constraints, wherein the set of predefined design constraints includes: minimum and maximum local forces applied to one or more of the surrounded teeth, the first shell, the second shell, or the interproximal reinforcement; a minimum and maximum rotational force applied to one or more of the surrounded tooth, the first shell, the second shell, or the interproximal support; minimum and maximum translational forces applied to one or more of the surrounded tooth, the first shell, the second shell, or the interproximal reinforcement; a minimum and maximum total force applied to one or more of the surrounded tooth, the first shell, the second shell, or the interproximal reinforcement; 57. The method of any one of embodiments 27-56, comprising one or more of the group consisting of a minimum strain and a maximum strain applied to the removable dental appliance when worn by a patient. Embodiment 58: A method according to any one of embodiments 27 to 57, wherein determining the removable dental appliance design includes modifying, by a computing device, the initial positions of one or more teeth of the patient to generate a modified dental structure, the modified dental structure representing a gradual repositioning of one or more teeth of the patient compared to the initial positions of the one or more teeth of the patient, and the removable dental appliance design is compatible with the modified dental structure.

[0062] Embodiment 59. The method of any one of embodiments 27-58, wherein the computing device comprises a plurality of computing devices operatively connected via one or more computer networks. Embodiment 60. A non-transitory computer-readable storage medium storing computer system executable instructions that, when executed, configure a processor to perform the method of any one of embodiments 27 to 59.

Claims

1. A removable dental appliance, An appliance body configured to at least partially encircle a plurality of teeth of a patient's dental arch, comprising: a first shell shaped to engage a first tooth of the plurality of teeth at an initial position of the first tooth; and a second shell shaped to engage a second tooth of the plurality of teeth at an initial position of the second tooth, the second tooth being adjacent to the first tooth; An orthosis body including: an interproximal reinforcement external to the appliance body that extends along an interproximal region between the first tooth and the second tooth from a first gingival margin of the appliance body on a facial side of the appliance body to a second gingival margin of the appliance body on a lingual side of the appliance body; the interproximal reinforcement causes the appliance body in the interproximal region to have a greater stiffness than the facial and lingual surfaces of the first shell; 1. A removable dental appliance, wherein the interproximal reinforcement is configured to contact and engage the appliance body with at least one of a lingual surface of the first tooth that is below a height of the contour of the first tooth or a facial surface of the first tooth that is below the height of the contour, such that the appliance body applies a force vector at a contact point on the first tooth to enable movement of the first tooth toward a desired position of the first tooth when the removable dental appliance is worn by the patient.

2. A removable dental appliance as described in claim 1, wherein the cross-section of the interproximal reinforcement is substantially constant along the length of the interproximal reinforcement from the end adjacent to the first gingival margin to the end adjacent to the second gingival margin.

3. 3. The removable dental appliance of claim 1, wherein the first shell includes a surface defining a cavity therein, the surface being shaped to receive the first tooth in a desired position, the interproximal reinforcement is configured to engage the lingual surface of the first tooth and the facial surface of the first tooth to bias an occlusal portion of the surface of the first shell toward the occlusal surface of the first tooth, and the appliance body is configured to apply the force vector at the contact point on the first tooth opposite the portion of the cavity to move the first tooth toward the portion of the cavity.

4. 4. The removable dental appliance of claim 1, wherein the interproximal reinforcement is biased toward an exterior of the appliance body near the occlusal surface of the appliance body and toward an interior of the appliance body at the first and second gingival margins to concentrate the force vector at the first tooth adjacent the gingival margin.

5. 10. A system comprising an ordered set of removable dental appliances configured to reposition one or more teeth of a patient, wherein each removable dental appliance in the set of removable dental appliances comprises a removable dental appliance according to any one of claims 1 to 4.

6. A method of operating a computer-aided manufacturing system for forming a removable dental appliance, comprising: receiving, by a computer of the computer-aided manufacturing system, a model of the patient's dental structure providing desired positions for a plurality of teeth; an additive manufacturing system of the computer-aided manufacturing system forming, based on the model, a removable dental appliance constituting the removable dental appliance of any one of claims 1 to 5; A method comprising:

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