Patent Description:
The field of orthodontics relates to repositioning a patient's teeth for improved function and aesthetic appearance. Orthodontic devices and treatment methods generally involve the application of forces to move teeth into a proper bite configuration, or occlusion. As one 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 may be placed in the slot of each bracket and serves as a track to guide movement of the teeth to desired orientations. The ends of the archwire are received in appliances known as buccal tubes that are secured to the patient's molar teeth. Such dental appliances remain in the mouth of the patient and are periodically adjusted by an orthodontist until proper alignment is achieved.

Orthodontic treatment may also involve the use of alignment trays, such as clear or transparent, polymer-based tooth positioning trays, often referred to as clear tray aligners (CTAs). For example, orthodontic treatment with CTAs may include forming a tray having shells that engage one or more teeth. Each shell may have a shape that is deformed upon being installed over the patient's teeth. The deformed position of a respective shell of the CTA may apply a force to a respective tooth toward a desired position of the tooth that is an intermediate position between an initial position of the respective tooth and a final position resulting from the orthodontic treatment. However, orthodontic treatment may require some tooth movements that are difficult for a CTA to achieve, such as, for example, tooth root movements and rotations of cuspids and bicuspids. In these instances, the forces and moments that a CTA is capable of applying directly to the surfaces of a tooth may be insufficient to achieve the desired tooth movement. Relevant prior art is exemplified by <CIT>, which, however, does not disclose a gingival ridge extending through the appliance body such that a portion of the gingival ridge is disposed on an exterior surface of the shell and a different portion of the gingival ridge is disposed on an interior surface of the shell.

Clear tray aligners often require attachments to achieve difficult tooth movements such as root movements and tooth rotations. Bonding attachments to the teeth is time consuming and can be problematic. Attachments are not aesthetically desirable and also make it difficult for patients to remove aligner trays from teeth. The disclosed removable dental appliances including gingival ridges facilitate difficult tooth movements without requiring the use of tooth attachments.

The details of one or more examples of this disclosure are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of this disclosure will be apparent from the description and drawings, and from the claims.

The disclosed removable dental appliances include gingival ridges that facilitate difficult tooth movements using a removable dental appliance without using tooth attachments. Clear tray aligners (CTAs), which are a type of removable dental appliance, are often used with attachments bonded to the surface of a tooth to achieve difficult tooth movements such as root movements and tooth rotations. The attachment acts as a handle on the tooth. Corresponding receptacles or apertures in the CTA engage with the attachments. The CTA can then apply forces and moments to teeth via the tooth attachment.

Bonding attachments to the teeth, however, is time consuming and can be problematic. Typical tooth attachments are bonded to the teeth with an attachment tray including pockets filled with a composite restorative. The attachment tray is placed on the patient's teeth and the composite restorative is bonded to the teeth. Under filling the pockets may result in the attachments debonding from the teeth. Over filling the pockets may result in excess composite restorative on the tooth surface (i.e., flash) that must be removed by grinding. If an attachment is not properly located or formed during the bonding process, the attachment may be removed by grinding the composite restorative, and a new attachment bonded to the tooth. Attachments that have not been well formed and located on the teeth can compromise the forces and moments that a CTA is capable of applying to teeth and may result in undesirable positions of the teeth at the end of orthodontic treatment. Also, during orthodontic treatment, the position of some teeth may lag the intended position in the treatment plan. The tooth position may lag significantly enough that the attachment on the tooth no longer engages properly into the corresponding receptacle or aperture in the CTA. In these circumstances, the CTA may become ineffective at applying desired forces to the tooth attachment and may even apply forces to the attachment in undesirable directions or with undesirable magnitudes that may move the tooth off course from the desired location in the treatment plan.

From the patient's perspective, tooth attachments may be uncomfortable, e.g., intruding on the tongue and inside of the cheeks, particularly when a CTA is not in the mouth covering the attachments. Attachments also may be aesthetically undesirable as the attachment and corresponding receptacles or aperture in the CTA are more conspicuous than a smooth CTA surface following the natural contour of the teeth. In addition, attachments on the teeth make removal of the CTA from the teeth considerably more difficult. The patient must remove CTAs from the mouth every time they eat or perform oral hygiene tasks. Particularly when a patient first has attachments bonded to their teeth, they can find removal of the CTA to be frustrating, uncomfortable, and time-consuming. Attachments may tend to betray the fundamental promise of CTAs as a completely removable appliance and can engender patient disappointment and resistance.

To improve the ability of the removable dental appliances to achieve difficult tooth movements without using tooth attachments, the disclosure describes removable dental appliances and orthodontic treatment techniques that include at least one gingival ridge in the removable dental appliance. Example removable dental appliances include an appliance body configured to at least partially surround two or more teeth of a dental arch of a patient. The appliance body includes a shell configured to receive one or more teeth of a patient and a gingival ridge extending from a first interproximal region of the appliance body at a mesial portion of the shell along a gingival edge of the shell to a second interproximal region of the appliance body at a distal portion of the shell. The gingival ridge enhances the stiffness of the gingival portion of the removable dental appliance, e.g., near the gingival margin. When worn by the patient, the enhanced stiffness of the gingival portion of the removable dental appliance may enhance contact between the removable dental appliance and the teeth below the respective height of contour of the respective teeth, e.g., near the gingival margin of the respective teeth. Enhancing contact below the height of contour increases retention of the removable dental appliance on the teeth and improves engagement of the removable dental appliance with the respective occlusal surfaces of the respective teeth. Enhancing contact below the height of contour and increasing engagement of the occlusal surfaces may improve the ability of the removable dental appliance to cause desired movements of teeth without attachments on the teeth.

During use of the removable dental appliance, engagement of the removable dental appliance with the teeth of the patient results in at least some of the removable dental appliance being deformed, e.g., from a physical configuration in which the removable dental appliance was formed to a configuration in which one or more teeth of the patient are received in the shell of the removable dental appliance. Deformation of the removable dental appliance results in a force being created in the shell and/or gingival ridge, such as, for example, compression, tension, shear, bending, or torsion forces. The force on the shell and/or the gingival ridge acts as a restorative force urging the shell and/or the gingival ridge in one or more directions that would result in the removable dental appliance becoming less deformed.

The restorative force results in force vectors at respective contact points on one or more teeth of the patient. For example, in a deformed configuration, respective shells of the removable dental appliance engage respective teeth at one or more contact points whereby the restorative force is transmitted to the teeth. By enhancing stiffness of the gingival portion of the appliance body and engagement of the teeth near the gingival and occlusal surface, the gingival ridge improves the determinability of the location contact points, e.g., as the removable dental appliance moves from the deformed configuration toward an undeformed configuration, and enables a greater force moment, e.g., torque, to be applied to a respective tooth. In this way, the gingival ridges improve the predictability of the magnitude and the direction of force vectors on the teeth to cause bone remodeling near the root of the respective teeth and produce desired tooth movements without bonding attachments to the teeth.

Additionally, or alternatively, deformation of the stiffened gingival portion of the appliance body, if any, may result in a force that is distributed by the gingival ridge to portions of the removable dental appliance adjacent to the gingival ridge, such as, for example, adjacent shells or adjacent gingival ridges. Distribution of force in a gingival ridge to adjacent portions of the removable dental appliance may concentrate deformation to a selected shell. Concentrating deformation to the selected shell may improve control of magnitude and direction of force vectors applied to the teeth by the selected shell when the removable dental appliance is worn by the patient. In this way, the gingival ridges improve control of force vectors on the teeth to cause bone remodeling near the root of the respective teeth and produce desired tooth movements without bonding attachments to the teeth. Additionally, or alternatively, gingival ridges may reduce the rate of the applied force degradation due to wear, material creep, stretching, moisture absorption, or the like. Sustaining applied forces to teeth at a desired magnitude for a longer time period will better sustain the rate of tooth movement, reduce the overall treatment time, and/or increase the duration a single removable dental appliance may be used during the course of orthodontic treatment.

<FIG> illustrate an example removable dental appliance <NUM> that includes a plurality of gingival ridges 102A-102D (collectively, "gingival ridges <NUM>"). Removable dental appliance <NUM> includes an appliance body <NUM> configured to at least partially surround a plurality of teeth of either the maxillary dental arch or the mandibular dental arch of a patient. For example, as illustrated in <FIG>, appliance body <NUM> is configured to surround at least one of the facial, lingual, and occlusal surfaces of the teeth (collectively, "teeth <NUM>") of a mandibular arch of the patient, e.g., tooth 106A. In some examples, appliance body <NUM> may surround different portions of different teeth <NUM> or overlap a portion of the gingiva of the patient. One tooth <NUM> is shown for purposes of illustration, although the number of teeth <NUM> may include all teeth <NUM> of the patient, such as, for example, fourteen teeth, less than fourteen (e.g., a patient having one or more extracted teeth), or more than fourteen (e.g., a patient having wisdom teeth or hyperdontia).

Removable dental appliance <NUM> may include an aligner tray. For example, appliance body <NUM> may include a plurality of tooth shells 108A-108N (collectively, "shells <NUM>") and gingival ridges <NUM>. Each respective shell of shells <NUM> is shaped to receive at least one respective tooth of teeth <NUM>. For example, shell 108D may be shaped to receive tooth 106A. In some examples, appliance body <NUM> may define a respective shell of shells <NUM> for each respective tooth of teeth <NUM>. In other examples, appliance body <NUM> may define fewer shells than teeth, e.g., a shell may receive more than one tooth or at least one of teeth <NUM> may not be surrounded by a shell of shells <NUM>. In other examples, appliance body <NUM> may define more shells <NUM> than teeth <NUM>, e.g., two or more shells or shell-like portions may surround at least a portion of at least one tooth or a shell in place to receive an unerupted tooth.

In some examples, a respective shell of shells <NUM> may be shaped to engage a contact point including at least one selected location having selected surface area of a respective tooth of teeth <NUM>. In some examples, shells <NUM> may surround the facial, lingual, and occlusal portions of teeth <NUM>. In some examples, shells <NUM> may surround fewer portions of teeth <NUM>, such as, for example, only the facial and lingual portions, or only one of the facial or lingual portions of teeth <NUM>. By selecting the shape of a respective shell of shells <NUM>, removable dental appliance <NUM> may control the location(s) and direction(s) of force(s) applied to a respective tooth of teeth <NUM>. In some examples, a thickness of a respective shell of shells <NUM> may range between about <NUM> millimeters and about <NUM> millimeters, such as between about <NUM> and about <NUM> millimeters, or between <NUM> millimeters and <NUM> millimeters.

In some examples, a respective shell of shells <NUM> may include a surface that defines a void internal to the respective shell, the surface shaped to receive respective tooth in a desired position. For example, as best illustrated in <FIG> and <FIG>, shell 108D includes an interior surface <NUM> that defines a void <NUM> internal to shell 108D. Surface <NUM> is shaped to receive tooth 106A in a desired position of tooth 106A. For example, removable dental appliance <NUM> may urge an occlusal surface <NUM> of tooth 106A from an initial position of tooth 106A toward a desired position of tooth 106A, such that occlusal surface <NUM> at least partially engages with surface <NUM>.

Appliance body <NUM> may include one or more anchor shells configured to receive one or more anchor teeth. In some examples, anchor teeth may include one or more molar teeth, premolar teeth, or both, and anchor shells may include corresponding shells, such as, for example, shells 108A-108D and <NUM>-108N. In other examples, anchor teeth may include one or more anterior teeth, or a combination of one or more anterior and posterior teeth. Anchor shells may be configured to allow portions of appliance body <NUM> to deform to result in a force sufficient to move one or more teeth (e.g., force sufficient to cause alveolar bone remodeling) without resulting in sufficient force to move the respective anchor teeth. In other examples, appliance body <NUM> may omit any one or more of anchor shells 108A-108D and <NUM>-108N.

Appliance body <NUM> includes gingival ridges <NUM>. Gingival ridges <NUM> may include any suitable height, e.g., extending in the gingival-occlusal direction. For example, the height of a respective gingival ridge of gingival ridges <NUM> may be between about <NUM> millimeter (mm) and about <NUM>, such as between about <NUM> and about <NUM>. Gingival ridges <NUM> may include any suitable thickness, e.g., extending from interior surface <NUM> of appliance body <NUM> into void <NUM>. For example, the thickness of a respective gingival ridge of gingival ridges <NUM> may be between about <NUM> millimeter and about <NUM> millimeters, or between about <NUM> millimeters and about <NUM> millimeters, or between about <NUM> and about <NUM> millimeters, or about <NUM> millimeters. In some examples, gingival ridges <NUM> may include a step change in thickness of appliance body <NUM>, e.g., a non-tapered change in total thickness of appliance body <NUM> from a thickness of a respective shell of shells <NUM> to a thickness of the respective shell and a respective gingival ridge of gingival ridges <NUM>. In some examples, gingival ridges <NUM> may include a tapered change in thickness of appliance body <NUM>. Gingival ridges <NUM> may include any suitable length, e.g., extending in the mesial-distal direction. For example, a respective gingival ridge of gingival ridges <NUM> may extend the entire distance from a first interproximal region mesial of a respective shell to a second interproximal region distal of the respective shell. By extending to interproximal regions mesial and/or distal to a respective shell of shells <NUM>, a respective gingival ridges <NUM> may enhance the stiffness of the respective shell at the gingival ridge by physically coupling to the relatively stiffer interproximal region of the appliance body <NUM> (e.g., compared to the relatively more flexible shell). In some examples, gingival ridges <NUM> may extend across one or more interproximal regions. By extending across one or more interproximal regions, gingival ridges <NUM> may stiffen two or more adjacent shells at gingival ridges <NUM>.

In some examples, gingival ridges <NUM> may extend across less than the entire mesial-distal length between one or more interproximal regions. For example, a respective gingival ridge of gingival ridges <NUM> may extend across a portion of a respective shell of shells <NUM>. In some examples, a respective gingival ridge of gingival ridges <NUM> may include a plurality of segments. Each segment of the plurality of segments may traverse a portion of the distance from a first interproximal region mesial to a second interproximal region distal to the respective shell. For example, as illustrated in <FIG>, gingival ridge 102B may include a mesial segment 103A and a distal segment 103B defining a flexible region 103C between mesial segment 103A and a distal segment 103B. By including a plurality of segments, the respective gingival ridge may allow for selected flexible regions between each segment of the plurality of segments. The selected flexibility at the selected flexible regions may enable better control of direction(s) and magnitude(s) of force(s) applied by the appliance body <NUM> to teeth <NUM> compared to gingival ridges <NUM> without a plurality of segments.

A respective gingival ridge of gingival ridges <NUM> may be positioned at or near a gingival-most edge of appliance body <NUM>. For example, gingival ridges <NUM> may be positioned up to about <NUM> millimeters, such as between about <NUM> millimeter and about <NUM> millimeters, from the gingival edge of appliance body <NUM> or a gingival margin of teeth <NUM> when removable dental appliance <NUM> is worn by the patient. In some examples, gingival ridges <NUM> may be positioned at the gingival-most edge of appliance body <NUM> to reduce exposure of an edge of appliance body <NUM> that may otherwise be lifted off the face of teeth <NUM> by gingival ridges <NUM> and cause irritation when worn by the patient. In some examples, gingival ridges <NUM> may be disposed on interior surfaces (e.g. interior surface <NUM>) of shells <NUM>. In some examples, gingival ridges <NUM> may extend through appliance body <NUM>, such that one or more portions of a respective gingival ridge of gingival ridges <NUM> is disposed on an interior surface of a respective shell of shells <NUM> and one or more different portions of the respective gingival ridge are disposed on an exterior surface of the respective shell. In some examples, a respective gingival ridge of gingival ridges <NUM> may be shaped to correspond to a contour of a respective tooth of teeth <NUM>, such as, for example, to correspond to a shape of the respective tooth below the height of contour of the respective tooth. By corresponding to contours of teeth, gingival ridges <NUM> may better grip teeth <NUM> compared to gingival ridges <NUM> that do not follow contours of teeth <NUM>.

The position and shape of a respective gingival ridge of gingival ridges <NUM> may enable the respective gingival ridge to engage a respective tooth of teeth <NUM>. For example, as illustrated in <FIG>, gingival ridge 102A is configured (e.g., positioned and shaped) to engage lingual surface <NUM> of tooth 106A below a height of contour <NUM> of tooth 106A and labial surface <NUM> of tooth 106A below height of contour <NUM>. The height of contour (or crest of curvature), e.g., height of contour <NUM> of tooth 106A, is the location on a tooth with the greatest amount of a curve or greatest convexity or bulge, farthest from the root axis line. The region of appliance body <NUM> below the height of contour may include an undercut near the gingival margin. Engaging at least one of the lingual surface or the labial surface of teeth <NUM> below the height of contour of teeth <NUM> may enable appliance body <NUM> to enhance contact between removable dental appliance <NUM> and teeth <NUM> below the respective height of contour of the respective teeth.

Enhancing contact of appliance body <NUM> with a tooth of teeth <NUM> below the height of contour may increase retention of removable dental appliance <NUM> on teeth <NUM> and improve engagement of removable dental appliance <NUM> with the respective occlusal surfaces of the respective teeth. For example, enhancing contact below height of contour <NUM> of tooth 106A and increasing engagement of occlusal surface <NUM> of tooth 106A may enable removable dental appliance <NUM> to apply a force vector at a contact point <NUM> on tooth 106A to cause movement of tooth 106A toward a desired position of tooth 106A when removable dental appliance <NUM> is worn by the patient. In some examples, gingival ridges <NUM> may enable a greater moment, e.g., torque, to be applied to a respective tooth; improve the determinability of the location contact points, e.g., as removable dental appliance <NUM> moves from the deformed configuration to an undeformed configuration; or both compared to removable dental appliances without gingival ridges. In this way, gingival ridges <NUM> improve the control of the magnitude and the direction of force vectors on teeth <NUM> to cause bone remodeling near the root of the respective teeth and produce desired tooth movements without bonding attachments to the teeth.

Removable dental appliance <NUM> may be formed with an initial, undeformed shape corresponding to desired positions of teeth <NUM> (or intermediate positions of teeth <NUM>), such that the shape of removable dental appliance <NUM> is different than a current position of teeth <NUM>. When removable dental appliance <NUM> is worn by the patient, appliance body <NUM> may deform to allow shells <NUM> to receive teeth <NUM>. The deformation of appliance body <NUM> may induce a force, such as at least one of compression, tension, shear, bending, and torsion, in one or more portions of appliance body <NUM>. In some examples, the force in appliance body <NUM> may be concentrated in one or more shells <NUM>. Each respective shell of shells <NUM> may be engaged with a respective tooth of teeth <NUM> and, in each respective shell of shells <NUM> including a force induced by the deformation of appliance body <NUM>, cause the force to be transferred to each respective tooth of teeth <NUM>. In this way, deformation of appliance body <NUM> may transfer a force, via shells <NUM>, to the teeth <NUM>.

Gingival ridges <NUM> may affect the deformation of appliance body <NUM>. For example, without gingival ridges <NUM>, a gingival portion of appliance body <NUM> (e.g., first gingival edge <NUM> on labial side <NUM> and second gingival edge <NUM> on lingual side <NUM>) (referred to herein as, "gingival portions <NUM> and <NUM>") may be more flexible than other portions of appliance body <NUM>, such as an occlusal surface <NUM> of appliance body <NUM>. As one example, the relative stiffness of occlusal surface <NUM> may be due, at least in part, to the undulated surface of occlusal surface <NUM> that follows the shape of the occlusal surface of teeth <NUM>. The relative flexibility of gingival portions <NUM> and <NUM> may be due to fewer bends or folds near the gingival margin of teeth <NUM>. Additionally, or alternatively, appliance body <NUM> may be thicker near occlusal surface <NUM> than near gingival portions <NUM> and <NUM>, the relatively thinner gingival portions <NUM> and <NUM> being more flexible than the relatively thicker occlusal surface <NUM>. Gingival ridges <NUM> may stiffen appliance body <NUM> at gingival portions <NUM> and <NUM> near gingival ridges <NUM>. For example, gingival ridges <NUM> may increase resistance to twisting about a path that follows the contour of the dental arch. In some examples, the increased stiffness of the appliance body <NUM> with gingival ridges <NUM> may increase resistance to various other local (e.g., within a respective shell of shells <NUM>) or universal (e.g., across appliance body <NUM>) bending and twisting motions. For example, gingival ridges 102A may result in appliance body <NUM> at interproximal regions 114A and 114B being stiffer than labial side <NUM> and/or lingual side <NUM> of shell 108D. By stiffening gingival portions <NUM> and/or <NUM>, appliance body <NUM> may have a more uniform stiffness characteristic at occlusal surface <NUM> and at gingival portions <NUM> and <NUM> compared to a removable dental appliance without gingival ridges <NUM>.

The relatively stiffer gingival portions <NUM> and <NUM> may improve the grip of removable dental appliance <NUM> on teeth <NUM> (e.g., the amount of contact between dental appliance <NUM> and teeth <NUM>). When the dental appliance is being installed on the dental arch and teeth <NUM> are being received in shells <NUM> of removable dental appliance <NUM>, shells <NUM> and gingival ridges <NUM> deform to allow teeth <NUM> to enter shells <NUM>. For example, the height of contour of tooth 106A may be nearer an occlusal surface <NUM> of tooth 106A than a gingival margin <NUM> at tooth 106A. Gingival portions <NUM> and <NUM>, at labial side <NUM> and lingual side <NUM> of shell 108D may flex to allow tooth 106A to enter shell 108D. In some examples, gingival ridge 102A may flex to allow tooth 106A to enter shell 108D. After tooth 106A is received in shell 108D, gingival ridge 102A may urge labial side <NUM> and lingual side <NUM> of shell 108D toward labial face <NUM> and lingual face <NUM> of tooth 106A below height of contour <NUM> of tooth 106A. In this way, gingival ridges <NUM> enhance engagement of removable dental appliance <NUM> below the height of contour.

In some examples, enhancing engagement of removable dental appliance <NUM> below the height of contour, e.g., by engaging a lingual surface and/or a labial surface of a respective tooth of teeth <NUM>, may urge an occlusal portion of the interior surface of a respective shell of shells <NUM> toward an occlusal surface of the respective tooth. For example, gingival ridge 102A may urge labial side <NUM> and lingual side <NUM> of shell 108D toward labial face <NUM> and lingual face <NUM> of tooth 106B below height of contour <NUM> of tooth 106B, thereby urging an occlusal portion of surface <NUM> toward occlusal surface <NUM> of tooth 106B. Urging an occlusal portion of surface <NUM> toward occlusal surface <NUM> of tooth 106B may enable at least a portion of surface <NUM> to engage with occlusal surface <NUM> of tooth <NUM>. In some examples, the enhanced engagement below the height of contour of a respective tooth of teeth <NUM> and the enhanced engagement with a respective occlusal surface of the respective tooth of teeth <NUM> may enable removable dental appliance <NUM> to form a force couple on the respective tooth. In some examples, the enhanced engagement below the height of contour of a respective tooth of teeth <NUM> and the enhanced engagement with a respective occlusal surface of the respective tooth of teeth <NUM> may improve determinability of the contact points between appliance body <NUM> and teeth <NUM>. For example, by concentrating engagement at or near the occlusal portions and gingival portions of teeth <NUM>. In this way, gingival ridges <NUM> may improve engagement of removable dental appliance <NUM> with teeth <NUM> to cause movements of teeth <NUM> without attachments.

In some examples, gingival ridges <NUM> may be biased into the interproximal spaces and/or lingual or labial faces of teeth <NUM> to improve engagement with the gingival portion of teeth <NUM>. For example, gingival ridges <NUM> may be biased outward (e.g., in a direction toward an exterior surface of appliance body <NUM>) near an occlusal portion of appliance body <NUM> and along the height of shells <NUM>, biased inward (e.g., in a direction toward an interior surface of appliance body <NUM>) near a gingival portion of appliance body <NUM>, or both. In some examples, a first portion of gingival ridges <NUM> may be biased inward and a second different portion of gingival ridges <NUM> may be biased outward. Biasing gingival ridges <NUM> in this way may further enhance engagement of appliance body <NUM> with the gingival portion of teeth <NUM>, the occlusal portion of teeth <NUM>, or both to enable a greater moment to teeth <NUM> compared to an appliance body <NUM> without biased gingival ridges <NUM>. For example, biasing gingival ridges <NUM> inward near a gingival margin of tooth <NUM> may reduce premature contact of appliance body <NUM> with the facial or lingual surfaces of teeth <NUM> by assuring that first contact occurs near the gingiva. Controlling contact in this way may be helpful when torqueing a tooth <NUM>, e.g., if neighboring teeth are prescribed first-order rotations that cause appliance body <NUM> deform away from tooth <NUM> along the gingival margin.

The direction of the force on a respective tooth of teeth <NUM> may result in part from one or more contact points of at least one surface of a respective shell of shells <NUM> with at least one surface of the respective tooth of teeth <NUM> and the position and shape of gingival ridges <NUM> relative to shells <NUM>. In some examples, the number of contact points, the total area of engagement, or both, of the respective shell of shells <NUM> with the respective tooth of teeth <NUM> may be greater than the number of contact points, the total area of engagement, or both of a removable dental appliance without gingival ridges. By increasing the number and/or control of contact points, the direction(s) and magnitude(s) of the force(s) to applied to teeth <NUM> may be more accurately controlled compared to an alignment tray without gingival ridges <NUM>.

For example, a force distributed substantially evenly across the facial surface of tooth 106A may cause a translation of tooth 106A in the lingual direction. Hence, to achieve a translation of tooth 106A, gingival ridge 102A may be positioned to shell 108D and shaped to distribute force substantially evenly across the facial surface of tooth 106A. A force concentrated on a mesial half of a facial surface of tooth 106A, or one half of a facial surface and the opposite half of the lingual surface of tooth 106A, may cause a rotation of tooth 106A in the lingual direction about an axis of rotation extending generally in the occlusal-gingival direction. Hence, to achieve a rotation of tooth 106A, gingival ridge 102A may be biased toward tooth 106A along a selected portion of shell 108D to cause a rotation of tooth 106A, e.g., to distribute force on one half of a facial surface of tooth 106A or one half of the facial surface and the opposite half of the lingual surface of tooth 106A. A force concentrated near a lingual-gingival margin and/or labial-gingival margin (or at least gingival to the height of contour) of tooth 106A may cause an extrusion of tooth 106A. Hence, to achieve an extrusion, gingival ridges 102A and 102B may be positioned on shell 108D and shaped to concentrate force gingival to the height of contour of tooth 106A, e.g., such that shell 108D is configured to pinch or clamp both the lingual and facial sides of tooth 106A. A force concentrated on a portion of both the facial and occlusal surfaces of a tooth may cause a crown tipping of the tooth in the lingual-gingival direction. A combination of a force concentrated at a facial-occlusal surface of a tooth and a force concentrated at a lingual-gingival surface of a tooth may cause a torqueing of the tooth with the crown moving in the lingual direction and the root moving in the facial direction.

As discussed above, a respective shell of shells <NUM> may include a surface that defines a void internal to the respective shell, the surface shaped to receive respective tooth in a desired position. Appliance body <NUM> may be configured to apply a respective force vector at a respective contact point on the respective tooth relative to the void to cause movement of the respective tooth toward the void. For example, as illustrated in <FIG>, shell 108D includes an interior surface <NUM> that defines a void <NUM> internal to shell 108D. Surface <NUM> is shaped to receive tooth 106A in a desired position of tooth 106A. In some examples, appliance body <NUM> may be configured to apply a force vector at contact point <NUM> on tooth 106A opposite from a portion <NUM> of void <NUM> to cause movement of tooth 106A toward portion <NUM> of void <NUM>. In some examples, surface <NUM> of shell 108D may define a second portion <NUM> of void <NUM>, and appliance body <NUM> may be configured to apply a second force vector at a second contact point <NUM> on tooth 106A opposite from second portion <NUM> of void <NUM> to cause movement of tooth 106A toward second portion <NUM> of void <NUM>. In some examples, contact points <NUM> and <NUM> may be on opposite sides of tooth 106A. In some examples, contact points <NUM> and <NUM> may be on the same side of tooth 106A. In some examples, contact point <NUM> may be located on an occlusal surface of tooth 106A and contact point <NUM> may be located on a gingival surface of the tooth. In some examples, contact point <NUM> may be located on lingual surface <NUM> of tooth 106A and contact point <NUM> may be located on a labial surface <NUM> of the tooth. In some examples, appliance body <NUM> may be configured to apply more than two force vectors at more than two contact points on a respective tooth to cause movement of the respective tooth toward one or more voids. The shape of a void may cause a specific movement of a respective tooth by providing areas of reduced resistance through which a respective tooth of teeth <NUM> may move in response to force vectors applied to the respective tooth when a removable dental appliance <NUM> is worn by the patient. In this way, voids internal to appliance body <NUM> may assist in urging a respective tooth of teeth <NUM> toward a desired position.

Other force vectors and combinations of force vectors that may result in one or more tooth movements are contemplated. For example, Table <NUM> includes type of desired tooth movements, respective thresholds for the respective movements, and example locations of gingival ridges relative to the moving tooth to achieve the respective movement. By selecting a shape of gingival ridges <NUM> and locations of gingival ridges <NUM> on shells <NUM>, removable dental appliance <NUM> may be configured to apply, via deformation of gingival ridges <NUM>, a force with a particular direction and magnitude to teeth <NUM> that may result in any one or more of a corresponding rotational, translational, extrusive, intrusive, tipping, or torqueing force to teeth <NUM>.

In some examples, the respective thresholds for the respective movements tooth movements indicate a threshold (minimum) amount of tooth movement above which gingival ridges <NUM> may be used to ensure that movement of teeth <NUM> is completed predictably. By selecting a shape of gingival ridges <NUM> and locations of gingival ridges <NUM> on shells <NUM>, removable dental appliance <NUM> may be configured to apply, via deformation of gingival ridges <NUM>, a force with a particular direction and magnitude to teeth <NUM> that may result in any one or more of a corresponding rotational, translational, extrusive, intrusive, tipping, or torqueing force to teeth <NUM>.

A respective gingival ridge of gingival ridges <NUM> may extend over at least a portion of one or more adjacent interproximal regions, e.g., interproximal regions 114A and 114B. Gingival ridges <NUM>, e.g., gingival ridge 102B, may include any suitable shape. In some examples, gingival ridges <NUM> may include a substantially smooth and continuous arcuate shape following the gingival portion (e.g., gingival portion <NUM> or <NUM>) of appliance body <NUM> in the mesial-distal direction. A substantially smooth and continuous arcuate shape may result in a substantially uniform (e.g., uniform or near uniform) stiffness characteristic of gingival ridges <NUM>. In some examples, gingival ridges <NUM> may include a serpentine shape or a zigzag shape extending along the gingival portion of appliance body <NUM> having two or more linear segments joined at an angle. Forming gingival ridges <NUM> with curving shapes, e.g., serpentine or zigzag shapes, may result in more controllable and appropriate engaged force levels and directions during tooth treatment intervals.

The cross-sectional shape of gingival ridges <NUM> may be substantially constant or vary along the length of gingival ridges <NUM>. The cross-sectional shape may include, for example, an elliptical shape, a rectangular shape, other geometrical shapes, or irregular shapes. In some examples, the cross-section of a respective gingival ridge of gingival ridges <NUM> may be configured to control deformation of the respective gingival ridge and, thereby, a magnitude and a direction of a force vector applied to a respective tooth of teeth <NUM> when removable dental appliance <NUM> is worn by the patient. For example, as illustrated in <FIG>, gingival ridge 102C may include a first region <NUM> having a relatively smaller cross-sectional area to increase the flexibility of the respective gingival ridge near the region. Additionally, or alternatively, first region <NUM> may include other features to increase the flexibility of first region <NUM>, such as a relatively flatter cross-section, cut-outs, areas of a material having a low elastic modulus, or the like. The relative flexibility of the respective gingival ridge near first region <NUM> may reduce the restorative force exerted by gingival ridge 102C when removable dental appliance <NUM> is worn by the patient.

Similarly, gingival ridge 102C may include a second region <NUM> having a relatively larger cross-sectional area to increase the stiffness of the respective gingival ridge near first region <NUM>. Additionally, or alternatively, second region <NUM> may include other features to increase the stiffness of second region <NUM>, such as a reinforcing rib or rail areas of a material having a higher elastic modulus, or the like. For example, as illustrated in <FIG>, appliance body <NUM> may define reinforcing rib <NUM> distal to gingival ridge 102A and reinforcing rib <NUM> mesial to gingival ridge 102A. Reinforcing ribs <NUM> and <NUM> may be positioned on an exterior surface of appliance body <NUM> at or near the interproximal regions between shell 108D and adjacent shells 108C and 108E. Although illustrated as near an interproximal region, in some examples, reinforcing ribs <NUM> and <NUM> may be positioned in a medial portion of shell 108D. Reinforcing ribs <NUM> and <NUM> may enhance the relative stiffness of gingival ridge 102A (or shell 108D) to increase the restorative force exerted by gingival ridge 102A (or shell 108D) when removable dental appliance <NUM> is worn by the patient. In some examples, reinforcing ribs <NUM> and <NUM> may counteract typical material creep and/or diminishing forces applied by removable dental appliance <NUM> over time. In this way, selecting the shape of gingival ridges <NUM> may control deformation of the respective gingival ridge and, thereby, a magnitude and a direction of a force vector applied to a respective tooth of teeth <NUM> when removable dental appliance <NUM> is worn by the patient.

The length of gingival ridges <NUM> in the distal-mesial direction may include any suitable length. In some examples, the length of gingival ridges <NUM> may affect the amount that gingival ridges <NUM> deform and the resulting force on teeth <NUM>. For example, a longer gingival ridge may result in greater restorative force in gingival ridges <NUM>, a longer distance of expression of the force in gingival ridges <NUM>, or both, compared to shorter gingival ridges <NUM>. In this way, the length of a respective gingival ridge of gingival ridges <NUM> may affect the force resulting from the deformation of the respective gingival ridge of gingival ridges <NUM> when removable dental appliance <NUM> is worn by the patient.

In some examples, as illustrated in <FIG>, gingival ridge 102D may protrude over a portion of a lingual gingival margin, a portion of a labial gingival margin, or both. By protruding over a portion of the gingival margin, gingival ridge 102D may be configured to anchor to at least a portion of the alveolar bone via the gingiva. For example, when worn by the patient, gingival ridge 102D may at least partially contact the gingiva overlying the alveolar process to result in at least a portion of the deformation of gingival ridge 102D. In this way, removable dental appliance <NUM> may be configured to utilize the alveolar process as an anchor. For example, including one or more gingival ridges <NUM> attached to one or more respective portions of shells <NUM> extending to contact the gingiva may access additional bracing provided by the extended surface indirectly engaging with the alveolar process without impeding mobility of teeth <NUM>, enable greater force to be applied to a selected tooth of teeth <NUM> while using the more rigid alveolar process as an anchor instead of neighboring teeth <NUM>, or both. As such, another advantage could be better control of tooth movements relative to a fixed reference (the alveolar process), without causing unwanted reactionary movements of neighboring teeth <NUM>.

Gingival ridges <NUM> may include any suitable material. In some examples, a respective gingival ridge of gingival ridges <NUM> may include a continuous or discontinuous region of one or more materials disposed on or integrally formed with appliance body <NUM>. In some examples, gingival ridges <NUM> and appliance body <NUM> may be formed from a unitary material. Gingival ridges <NUM> may be formed of a material of a relatively higher modulus of elasticity compared to appliance body <NUM>. Forming gingival ridges <NUM> from a material of a higher modulus of elasticity may stiffen the gingival edge of appliance body <NUM> relative to adjacent portions of appliance body <NUM>, increase the durability of removable dental appliance <NUM>, and/or improve control of direction of the force applied to shells <NUM>. In some examples, a respective gingival ridge of gingival ridges <NUM> may include 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 CCM®), or cobalt-chromium-tungsten (CoCrW). Metal wire includes braided and non-braided wires and wires having any suitable cross-sectional shape, such as elliptical or rectangular. In some examples, a respective gingival ridge of gingival ridges <NUM> may include a polymeric rib including, but not limited to, polylactic acid; epoxy; silicones; polyesters; polyurethanes; polycarbonate; thiol-ene polymers; acrylate polymers such as urethane, (meth)acrylate polymers or poly(methyl methacrylate), polyalkylene oxide di(meth)acrylate, alkane diol di(meth)acrylate, aliphatic (meth)acrylates, silicone (meth)acrylate; polyethylene terephthalate based polymers such as polyethylene terephthalate glycol; polypropylene; ethylene-vinyl acetate; nylon; acetal resin (POM or Delrin®); acrylonitrile butadiene styrene; or combinations thereof. In some examples, the polymeric rib may include polymers configured to be dispensed using fused deposition modeling (FDM) printing processes, such as, polymers suitable for robotically dispensing a bead or beads of the polymer onto the surface of a removable dental appliance using a heated extruder nozzle. Using FDM printing may allow for controlling thickness in select areas of the removable dental appliance, e.g., the gingival ridges <NUM>, or controlling material properties compared to the bulk material of the removable dental appliance. In examples, in which the polymeric rib material and the removable dental appliance material both include thermoplastics, FDM printed material may fuse to the removable dental appliance material.

Gingival ridges <NUM> may be attached to appliance body <NUM> using any suitable attachment means. A respective gingival ridge of gingival ridges <NUM> and/or appliance body <NUM> may be shaped to form a stepwise joint or a tapered joint when the respective gingival ridge is attached to appliance body <NUM>. In some examples, gingival ridges <NUM> may be integrally formed with appliance body <NUM>. For example, removable dental appliance <NUM> may include a unitary polymer including appliance body <NUM> and gingival ridges <NUM>. In some examples, gingival ridges <NUM> may be physically separate from and mechanically attached to appliance body <NUM> along one or more portions of gingival ridges <NUM>. In some examples, a respective gingival ridge of gingival ridges <NUM> may be adhered to appliance body <NUM> along the entire length of the respective gingival ridge, a portion of the respective gingival ridge, or two or more discontinuous portions of the respective gingival ridge. A suitable adhesive may include, for example, epoxy resins, polyurethanes, cyanoacrylates, acrylics, silicones, or the like. In some examples, a respective gingival ridge or gingival ridges <NUM> may be at least partially surrounded by two or more material layers forming appliance body <NUM>. For example, gingival ridges <NUM> may be formed or positioned on a first material layer of appliance body <NUM> and a second material layer of appliance body <NUM> may be formed or placed over the first material layer and the gingival ridges <NUM>.

In some examples, appliance body <NUM> may define one or more alignment guides configured to mechanically attach a respective gingival ridge of gingival ridges <NUM> to appliance body <NUM>. For example, an alignment guide maybe integrally formed with appliance body <NUM> along a gingival edge of appliance body <NUM>. The alignment guide may be configured to receive a respective gingival ridge of gingival ridges <NUM> (e.g., gingival ridge 102A). For example, the alignment guide may be shaped to engage a respective gingival ridge of gingival ridges <NUM> in a push-to-fit or push-to-connect arrangement. As one example, the alignment guide may include a recess shaped to receive the shape of a respective gingival ridge of gingival ridges <NUM> and one or more ridges or posts integrally formed with appliance body <NUM>. The appliance body <NUM>, such as the one or more ridges or posts, may deform when the respective gingival ridge of gingival ridges <NUM> is inserted (e.g., pushed) into the recess to allow the respective gingival ridge to seat in the recess. The one or more ridges or posts may then return to an undeformed configuration to retain the respective gingival ridge in the recess. In some examples, a combination of mechanical attachments may be used to attach gingival ridges <NUM> to appliance body <NUM>. In some examples, a first portion of a respective gingival ridge of gingival ridges <NUM> may be fixed to appliance body <NUM> and a second portion of the respective gingival ridge may be secured, but free to travel in a selected direction, e.g., such as secured in an elongate recess and allowed to travel along the longitudinal axis of the elongate recess. By fixing selected portions of gingival ridges <NUM> to appliance body <NUM> while other portions of gingival ridges <NUM> may travel in a selected direction, removable dental appliance <NUM> may control the location or locations where a restorative force on gingival ridges <NUM> is transferred to appliance body <NUM>. For example, in examples in which gingival ridges <NUM> are fixed to appliance body <NUM> near interproximal regions, the restorative force from the deformation of gingival ridges <NUM> may be substantially transferred to a contact point near the respective interproximal regions. Force transfer via engagement near the interproximal regions may enable or improve desired tooth movements such as rotations, torqueing, tipping, or extrusions. In this way, selecting the type and location of attachment of gingival ridges <NUM> or appliance body <NUM> may affect a magnitude and/or a force vector applied to teeth <NUM> when removable dental appliance <NUM> is worn by the patient.

By selecting the material, shape, length, and attachment of a respective gingival ridge of gingival ridges <NUM>, removable dental appliance <NUM> may control at least one of a direction, a magnitude, and a length of expression of a force on a respective shell of shells <NUM> resulting from deformation of appliance body <NUM> when removable dental appliance <NUM> is worn by the patient.

In some examples, appliance body <NUM> may be formed from a unitary material, e.g., a single, uniform material. The unitary material may include a single polymer, or substantially homogeneous mixture of one or more polymers. For example, removable dental appliance <NUM> may consist of a single, continuous 3D printed or thermoformed component. In other examples, appliance body <NUM> may include a multi-layer material. The multi-layer material may include multiple layers of a single material, e.g., a single polymer, or multiple layers of a plurality of materials, e.g., two or more polymers, a polymer and another material. Multi-layer materials may enable one or more portions of appliance body <NUM> to be formed with a plurality of layers having different elastic modulus to enable selection of force characteristics, displacement characteristics, or both of gingival ridges <NUM>. For example, removable dental appliance <NUM> may consist of a multilayer 3D printed or thermoformed component. Suitable polymers may include, but are not limited to, (meth)acrylate polymer; epoxy; silicones; polyesters; polyurethanes; polycarbonate; thiol-ene polymers; acrylate polymers such as urethane (meth)acrylate polymers, polyalkylene oxide di(meth)acrylate, alkane diol di(meth)acrylate, aliphatic (meth)acrylates, silicone (meth)acrylate; polyethylene terephthalate based polymers such as polyethylene terephthalate glycol (PETG); polypropylene; ethylene-vinyl acetate; or combinations thereof. In the same or different examples, removable dental appliance <NUM> may include chamfers or fillets on edges of appliance body <NUM> and other spaces. Such chamfers or fillets may improve patient comfort and reduce the visibility of removable dental appliance <NUM>.

In other examples, removable dental appliance <NUM> may include metallic components configured to enhance forces applied by removable dental appliance <NUM> to one or more of the surrounded teeth <NUM>. For example, the metallic component may comprise a wire or ribbon extending through at least a portion of appliance body <NUM>, such as gingival ridges <NUM>. In some examples, removable dental appliance <NUM> may include one or more other metal components, such as metal occlusal components, where greater durability is needed to overcome the stress of high-pressure occlusal contact, such as bruxing, or mastication. In some examples, removable dental appliance <NUM> may include catches configured to engage an anchorage device implanted within the patient, e.g., a temporary anchorage device or mini-screw, or attachments fixed to a surface a of tooth of teeth <NUM>. For example, catches may be positioned on anchor shells 108A-104D and <NUM>-104N to connect to an anchorage device on anchor teeth, such as molars or premolars. In this manner, such removable dental appliances <NUM> may provide a hybrid construction of metal and plastic.

In some examples, a metallic component may be formed on removable dental appliance <NUM> using an electroforming (or electrodeposition) process. For example, an electrically conductive coating may be applied to selected areas of removable dental appliance <NUM>, such as by electroless plating, physical vapor deposition (e.g. electron beam physical vapor deposition, evaporative deposition, sputter deposition, etc.), or conductive paint. The selected areas may be masked prior to deposition of the conductive coating to ensure that only the selected areas are made 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., a negative terminal of a DC voltage source, and piece of donor metal may be connected to a second terminal of the power source, e.g., a positive terminal of the DC voltage source. Then removable dental appliance may be immersed in an electrolyte solution, such as water, salt water, or acid. Current applied to the terminals may result in migration of metal ions through the solution from the donor metal to the conductive surface of the appliance where they are deposited. The duration of electroplating may be controlled to control the thickness of the metal coating. In some examples, masking may include placing a non-conductive vertical dam on either side of the conductive area to control a shape of the deposited metal, e.g., to make sidewalls of the deposited metal perpendicular to the substrate surface. In some examples, the dam might may serve to brace the metal reinforcement and retain it in its proper position while under stress, minimizing the possibility of detachment. In some examples, the dam 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 examples, 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., lessen the possibility of allergic reaction or corrosion) the bulk metal may be coated with one or more inert metals, such as gold, platinum, or rhodium; a metal oxide; or a polymer. Additionally, or alternatively, the entire outer surface of the removable dental appliance may be coated with another layer of polymer or thermoformed polymeric sheet.

While plastic components may be generally clear for reduced visibility, metal components may include plating or other coloring to reduce visibility of removable dental appliance <NUM> when worn by the patient. For example, metal components positioned near teeth <NUM> of a patient when worn may include white colored coating or plating, such as, for example, rhodium, silver, white anodized titanium, Teflon, PTFE, and the like, or be formed of a white colored metal, such as, for example, rhodium, silver, white anodized titanium, and the like. Metal components positioned elsewhere may be colored to generally match tissue color within the mouth of the patient.

<FIG> is a block diagram illustrating an example computer environment <NUM> in which clinic <NUM> and manufacturing facility <NUM> communicate information throughout a manufacturing process of a set of removable dental appliances <NUM> for patient <NUM>. The set of removable dental appliances <NUM> may include removable dental appliance <NUM>. As discussed above, removable dental appliance <NUM> includes shells and at least one gingival ridge. Initially, an orthodontic practitioner of clinic <NUM> generates one or more images of a dental anatomy of patient <NUM> using any suitable imaging technique and generates digital dental anatomy data <NUM> (e.g., a digital representation of patient's <NUM> tooth structure). For example, the practitioner may generate X RAY images that can be digitally scanned. Alternatively, the practitioner may capture digital images of the patient tooth structure using, for example, conventional computed tomography (CT), laser scanning, intra-oral scanning, CT scans of dental impressions, scans of dental casts poured from impressions, ultrasound instrumentation, 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 hand-held intra-oral scanner such as the intra-oral scanner using active wavefront sampling developed by Brontes Technologies, Inc. (Lexington, Massachusetts) and described in <CIT>). Alternatively, other intra-oral scanners or intra-oral contact probes may be used. As another option, the digital dental anatomy data <NUM> may be provided by scanning a negative impression of the teeth of patient <NUM>. As still another option, the digital dental anatomy data <NUM> may be provided by imaging a positive physical model of the teeth of patient <NUM> or by using a contact probe on a model of the teeth of patient <NUM>. The model used for scanning may be made, for example, by casting an impression of the dentition of patient <NUM> 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 cure. Any suitable scanning technique may be used for scanning the model, including those described above. Other possible scanning methods are described in, for example, <CIT>) and <CIT>).

In addition to providing digital images by scanning the exposed surfaces of the teeth, it is possible to image non-visible features of the dentition, such as the roots of the teeth of patient <NUM> and the jaw bones of patient <NUM>. In some embodiments, the digital dental anatomy data <NUM> is formed by providing several 3D images of these features and subsequently "stitching" them together. These different images need not be provided using the same imaging technique. For example, a digital image of teeth roots provided with a CT scan may be integrated with a digital image of the teeth crowns provided with an intraoral visible light scanner. Scaling and registering of two-dimensional (2D) dental images with 3D dental images is described in <CIT>). Issued <CIT>), and <CIT>), describe using techniques of integrating digital images provided from various 3D sources. Accordingly, the term "imaging" as it is used herein is not limited to normal photographic imaging of visually apparent structures but includes imaging of dental anatomies that are hidden from view. The dental anatomy may include, but is not limited to, any portion of crowns or roots of one or more teeth of a dental arch, gingiva, periodontal ligaments, alveolar bone, cortical bone, implants, artificial crowns, bridges, veneers, dentures, orthodontic appliances, or any structure that could be considered part of the dentition before, during, or after treatment.

To generate digital dental anatomy data <NUM>, a computer must transform raw data from the imaging systems into usable digital models. For example, for raw data representing the shapes of teeth received by a computer, the raw data is often little more than a point cloud in 3D space. Typically, this point cloud is surfaced to create 3D object models of the patient's dentition, including one or more teeth, gingival tissue, and other surrounding oral structure. For this data to be useful in orthodontic diagnosis and treatment, the computer may "segment" dentition surfaces to produce one or more discrete, movable 3D tooth object models representing individual teeth. The computer may further separate these tooth models from the gingiva into separate objects.

Segmentation allows a user to characterize and manipulate the teeth arrangement as a set of individual objects. Advantageously, the computer may derive diagnostic information such as arch length, bite setting, interstitial spacing between adjacent teeth, and even American Board of Orthodontics (ABO) objective grading from these models. As a further benefit, the digital orthodontic setups may provide flexibility in the manufacturing process. By replacing physical processes with digital processes, the data acquisition step and data manipulation steps can be executed at separate locations without the need to transport stone models or impressions from one location to another. Reducing or eliminating the need for shipping physical objects back and forth can result in significant cost savings to both customers and manufacturers of customized appliances.

After generating digital dental anatomy data <NUM>, clinic <NUM> may store digital dental anatomy data <NUM> within a patient record in a database. Clinic <NUM> may, for example, update a local database having a plurality of patient records. Alternatively, clinic <NUM> may remotely update a central database (optionally within manufacturing facility <NUM>) via network <NUM>. After digital dental anatomy data <NUM> is stored, clinic <NUM> electronically communicates digital dental anatomy data <NUM> to manufacturing facility <NUM>. Alternatively, manufacturing facility <NUM> may retrieve digital dental anatomy data <NUM> from the central database. Alternatively, manufacturing facility <NUM> may retrieve preexisting digital dental anatomy data <NUM> from a data source unassociated with clinic <NUM>.

Clinic <NUM> may also forward prescription data <NUM> conveying general information regarding a practitioner's diagnosis and treatment plan for patient <NUM> to manufacturing facility <NUM>. In some examples, prescription data <NUM> may be more specific. For example, digital dental anatomy data <NUM> may be a digital representation of the dental anatomy of patient <NUM>. The practitioner of clinic <NUM> may review the digital representation and indicate at least one of desired movements, spacing, or final positions of individual teeth of patient <NUM>. For example, the desired movements, spacing, and final positions of individual teeth of patient <NUM> may affect the forces to be applied to the teeth of patient <NUM> at each stage of treatment by each removable dental appliance of the set of removable dental appliances <NUM>. As discussed above, the forces applied by each removable dental appliance <NUM> of the set of removable dental appliances <NUM> may be determined by selecting the dimensions, shapes, and positions of the gingival ridge (e.g., gingival ridges <NUM>) and shells (e.g., shells <NUM>). The at least one of desired movements, spacing, or final positions of individual teeth of patient <NUM> may enable one or more of the practitioner, a technician at manufacturing facility <NUM>, and a computer at manufacturing facility <NUM> to determine at least one of selected dimensions, shapes, and positions of at least one of the shells, and gingival ridges. In this way, digital dental anatomy data <NUM> may include at least one of practitioner, technician, or computer selected dimensions, shapes, and positions of at least one of the gingival ridge and the shells of each of removable dental appliance of the set of removable dental appliances <NUM> to result in the desired movement of the teeth of patient <NUM>. Following review of the digital representation, the digital dental anatomy data <NUM> that includes the selected dimensions, shapes, and positions of the gingival ridge and shells of each removable dental appliance of the set of removable dental appliances <NUM>, may be forwarded to manufacturing facility <NUM>. Manufacturing facility <NUM> may be located off-site or located with clinic <NUM>.

For example, each clinic <NUM> may act as manufacturing facility <NUM> such that a treatment plan and digital design may be performed entirely by a clinical practitioner, or an assistant, in the clinical setting, using software installed locally. The manufacturing may be performed in the clinic, as well, by using a 3D printer (or by other methods of additive manufacturing). A 3D printer allows manufacturing of intricate features of a dental appliance or a physical representation of the dental anatomy of patient <NUM> through additive manufacturing. The 3D printer may use iterative digital designs of original dental anatomy of patient <NUM> as well as a desired dental anatomy of patient <NUM> to produce multiple digital appliances and/or digital appliance patterns customized to produce the desired dental anatomy of patient <NUM>. In some examples, other methods of additive manufacturing may include, for example, fused deposition modeling using a <NUM>- or <NUM>-axis cartesian robot or articulating arm robot to dispense material onto the surface of a removable dental appliance after thermoforming, 3D printing, and/or milling the removable dental appliance. Manufacturing may include post-processing, such as milling, to remove uncured resin and remove support structures, or to assemble various components, which may also be necessary and could also be performed in a clinical setting.

Manufacturing facility <NUM> utilizes digital dental anatomy data <NUM> of patient <NUM> to construct the set of removable dental appliances <NUM> to reposition teeth of patient <NUM>. Sometime thereafter, manufacturing facility <NUM> forwards the set of removable dental appliances <NUM> to clinic <NUM> or, alternatively, directly to patient <NUM>. For example, the set of removable dental appliances <NUM> may be an ordered set of removable dental appliances. Patient <NUM> then wears the removable dental appliances <NUM> in the set of removable dental appliances <NUM> sequentially over time according to a prescribed schedule to reposition the teeth of patient <NUM>. For example, patient <NUM> may wear each removable dental appliance in the set of removable dental appliances <NUM> for a period of between about <NUM> week and about <NUM> weeks, such as between about <NUM> weeks and about <NUM> weeks, or about <NUM> weeks. Optionally, patient <NUM> may return to clinic <NUM> for periodic monitoring of the progress of the treatment with removable dental appliances <NUM>.

During such periodic monitoring, a clinician may adjust the prescribed schedule of patient <NUM> for wearing the removable dental appliances in the set of removable dental appliances <NUM> sequentially over time. Monitoring generally includes visual inspection of the teeth of patient <NUM> and may also include imaging to generate digital dental anatomy data. In some relatively uncommon circumstances, the clinician may decide to interrupt the treatment of patient <NUM> with the set of removable dental appliances <NUM>, for example, by sending the newly generated digital dental anatomy data <NUM> to manufacturing facility <NUM> in order to produce a new set of removable dental appliances <NUM>. In the same or different examples, the clinician may send newly generated digital dental anatomy data <NUM> to manufacturing facility <NUM> following the completion of the prescribed schedule of the treatment with removable dental appliances <NUM>. In addition, following the completion of the prescribed schedule of the treatment with removable dental appliances <NUM>, the clinician may request a new set of removable dental appliances from manufacturing facility <NUM> to continue treatment of patient <NUM>.

<FIG> is a flow diagram illustrating an example process of generating digital dental anatomy data <NUM>. Initially, a practitioner at clinic <NUM> collects patient identity and other information from patient <NUM> and creates a patient record (<NUM>). As described, the patient record may be located within clinic <NUM> and optionally configured to share data with a database within manufacturing facility <NUM>. Alternatively, the patient record may be located within a database at manufacturing facility <NUM> that is remotely accessible to clinic <NUM> via network <NUM> or within a database that is remotely accessible by both manufacturing facility <NUM> and clinic <NUM>.

Next, digital dental anatomy data <NUM> of patient <NUM> may be generated using any suitable technique (<NUM>), to thereby create a virtual dental anatomy. Digital dental anatomy data <NUM> may be comprised of a two-dimensional (2D) image and/or a three-dimensional (3D) representation of the dental anatomy.

In one example, 3D representations of a dental anatomy are generated using a cone beam computerized tomography (CBCT) scanner, such as an i-CAT 3D dental imaging device (available from Imaging Sciences International, LLC; <NUM> N Penn Road, Hatfield, PA). Clinic <NUM> stores the 3D digital dental anatomy data <NUM> (in the form of radiological images) generated from the CBCT scanner in the database located within clinic <NUM>, or alternatively, within manufacturing facility <NUM>. The computing system processes the digital dental anatomy data <NUM> from the CBCT scanner, which may be in the form of a plurality of slices, to compute a digital representation of the tooth structure that may be manipulated within the 3D modeling environment.

If 2D radiological images are used (<NUM>), then the practitioner may further generate 3D digital data (<NUM>). The 3D digital dental anatomy data <NUM> may be produced by, for example, forming and subsequently digitally scanning a physical impression or casting of the tooth structure of patient <NUM>. For example, a physical impression or casting of a dental arch of patient <NUM> may be scanned using a visible light scanner, such as an OM-3R scanner (available from Laser Design, Inc. of Minneapolis, Minnesota) or an ATOS scanner (available from GOM GmbH of Braunschweig, Germany). Alternatively, the practitioner may generate the 3D digital dental anatomy data <NUM> of the occlusal service by use of an intra-oral scan of the dental arch of patient <NUM>, or existing 3D tooth data. For example, <CIT>, describes a method of forming a digital scan from a casting or an impression described in <CIT>, may be used. Additionally, or alternatively, <CIT>, describes techniques for defining a virtual tooth surface and virtual tooth coordinate system as described in <CIT> may be used. In any case, the digital data are digitally registered within the 3D modeling environment to form a composite digital representation of a tooth structure, which may include the tooth roots as well as the occlusal surfaces.

In one example, 2D radiological images and the 3D digital data for the occlusal surface of the dental arch are registered by first attaching registration markers (e.g., fiducial markers or a pedestal having known geometry) to the tooth structure of patient <NUM> prior to generating both the radiological images and the 3D digital scan. Thereafter, the digital representation of the registration markers within the 2D radiological image and the 3D digital data may be aligned within a 3D modeling environment using registration techniques described in <CIT>.

In another example, 3D digital data of the tooth structure is generated by combining two 3D digital representations of the tooth structure. For example, a first 3D digital representation may be a relatively low-resolution image of the roots obtained from a CBCT scanner (e.g., an i-CAT 3D dental imaging device) and the second 3D digital representation may be a relatively high-resolution image of the crowns of the teeth obtained from an industrial CT scan of an impression or a visible light (e.g., laser) scan of a casting of the dental arch of the patient. The 3D digital representations may be registered using a software program that enables the 3D representations to be manipulated within a computer environment (e.g., Geomagic Studio software (available from 3D Systems, Inc. ; <NUM> Three D Systems Circle, Rock Hill, South Carolina), or alternatively, registration techniques described in <CIT> may be used.

Next, a computer system executing 3D modeling software renders a resultant digital representation of the tooth structure, including the occlusal surface as well as the root structure of the patient's dental arch. Modeling software provides a user interface that allows the practitioner to manipulate digital representations of the teeth in 3D space relative to the digital representation of the dental arch of patient <NUM>. By interacting with the computer system, the practitioner generates treatment information, such as by selecting indications of the final positions of individual teeth of patient <NUM>, duration of a respective stage of treatment, or number of treatment stages, the direction or magnitude of forces on the teeth of patient <NUM> during a stage of treatment, or the like (<NUM>). For example, the final positions of individual teeth of patient <NUM>, duration of a respective stage of treatment, or number of treatment stages may affect the direction or magnitude of forces on the teeth of patient <NUM> at each stage of treatment by each removable dental appliance of the set of removable dental appliances <NUM>. In some examples, gingival ridge may be used during at least one, but fewer than all stages of treatment. As discussed above, the forces applied by each removable dental appliance <NUM> of the set of removable dental appliances <NUM> may be determined by selecting the dimensions, shapes, and positions of the gingival ridge (e.g., gingival ridges <NUM>) and shells (e.g., shells <NUM>). In this way, updating the database with diagnostic and treatment information (<NUM>) may include determining or selecting by the practitioner, a technician, or automatically by a computer the dimensions, shapes, and positions of the gingival ridge and shells of each of removable dental appliance of the set of removable dental appliances <NUM> to result in the desired movement of the teeth of patient <NUM>.

Once the practitioner has finished conveying general information regarding a diagnosis and treatment plan within the 3D environment, the computer system updates the database associated with the patient record to record the prescription data <NUM> conveying general information regarding a diagnosis and treatment plan as specified by the practitioner (<NUM>). Thereafter, the prescription data <NUM> is relayed to manufacturing facility <NUM> for manufacturing facility <NUM> to construct one or more removable dental appliances including gingival ridges, such as removable dental appliances <NUM> (<NUM>).

Although described with respect to an orthodontic practitioner located at an orthodontic clinic, one or more of the steps discussed with respect to <FIG> may be performed by a remote user, such as a user located at manufacturing facility <NUM>. For example, the orthodontic practitioner may only send radiological image data and an impression or casting of the patient to manufacturing facility <NUM>, where a user interacts with a computer system to develop a treatment plan within a 3D modeling environment. Optionally, a digital representation of the treatment plan within the 3D modeling environment may then be transmitted to the orthodontic practitioner of clinic <NUM>, who may review the treatment plan and either send back his or her approval or indicate desired changes.

<FIG> is a block diagram illustrating an example of a client computing device <NUM> connected to manufacturing facility <NUM> via network <NUM> to generate digital dental anatomy data. In the illustrated example, client computing device <NUM> provides an operating environment for modeling software <NUM>. Modeling software <NUM> presents a modeling environment for modeling and depicting the 3D representation of the teeth of patient <NUM>. In the illustrated example, modeling software <NUM> includes user interface <NUM>, alignment module <NUM>, and rendering engine <NUM>.

User interface <NUM> provides a graphical user interface (GUI) that visually displays the 3D representation of the teeth of patient <NUM>. In addition, user interface <NUM> provides an interface for receiving input from practitioner <NUM>, e.g., via a keyboard and a pointing device, a touchscreen, or the like, for manipulating the teeth of patient <NUM> within the modeled dental arch.

Modeling software <NUM> may be accessible to manufacturing facility <NUM> via network interface <NUM>. Modeling software <NUM> interacts with database <NUM> to access a variety of data, such as treatment data <NUM>, 3D data <NUM> relating to the tooth structure of patient <NUM>, and patient data <NUM>. Database <NUM> may be represented in a variety of forms including data storage files, lookup tables, or a database management system (DBMS) executing on one or more database servers. The database management system may be a relational (RDBMS), hierarchical (HDBMS), multi-dimensional (MDBMS), object oriented (ODBMS or OODBMS) or object relational (ORDBMS) database management system. The data may, for example, be stored within a single relational database, such as SQL Server from Microsoft Corporation. Although illustrated as local to client computing device <NUM>, database <NUM> may be located remote from the client computing device <NUM> and coupled to the client computing device <NUM> via a public or private network, e.g., network <NUM>.

Treatment data <NUM> describes diagnosis or repositioning information for the teeth of patient <NUM> selected by practitioner <NUM> and positioned within the 3D modeling environment. For example, treatment data <NUM> may include the dimensions, shapes, and positions of the gingival ridge (e.g., gingival ridges <NUM>) and shells (e.g., shells <NUM>) that may result in a selected magnitude and direction of force vectors to be applied to patient's teeth (e.g., teeth <NUM>) throughout the treatment plans.

Patient data <NUM> describes a set of one or more patients, e.g., patient <NUM>, associated with practitioner <NUM>. For example, patient data <NUM> specifies general information, such as a name, birth date, and a dental history, for each patient <NUM>.

Rendering engine <NUM> accesses and renders 3D data <NUM> to generate the 3D view presented to practitioner <NUM> by user interface <NUM>. More specifically, 3D data <NUM> includes information defining the 3D objects that represent each tooth (optionally including roots), and jaw bone within the 3D environment. Rendering engine <NUM> processes each object to render a 3D triangular mesh based on viewing perspective of practitioner <NUM> within the 3D environment. User interface <NUM> displays the rendered 3D triangular mesh to practitioner <NUM> and allows practitioner <NUM> to change viewing perspectives and manipulate objects within the 3D environment.

<CIT>, and <CIT>, describes other examples for computer systems and 3D modeling software having user interfaces that may be used with the techniques described herein.

Client computing device <NUM> includes processor <NUM> and memory <NUM> to store and execute modeling software <NUM>. Memory <NUM> may represent any volatile or non-volatile storage elements. 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 a hard-disk, magnetic tape, a magnetic or optical data storage media, a compact disk (CD), a digital versatile disk (DVD), a Blu-ray disk, and a holographic data storage media.

Processor <NUM> 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 executing the techniques described herein. In one example, memory <NUM> may store program instructions (e.g., software instructions) that are executed by processor <NUM> to carry out the techniques described herein. In other examples, the techniques may be executed by specifically programmed circuitry of processor <NUM>. In these or other ways, processor <NUM> may be configured to execute the techniques described herein.

Client computing device <NUM> is configured to send a digital representation of a 3D tooth structure of a patient, and optionally, treatment data <NUM> and/or patient data <NUM> to computer <NUM> of manufacturing facility <NUM> via network <NUM>. Computer <NUM> includes user interface <NUM>. User interface <NUM> provides a GUI that visually displays the 3D representation of the digital model of teeth. In addition, user interface <NUM> provides an interface for receiving input from a user, e.g., via a keyboard and a pointing device, for manipulating a patient's teeth within the digital representation of the 3D tooth structure of the patient.

Computer <NUM> may further be configured to automatically determine dimensions and shapes of each removable dental appliance of a set of removable dental appliances <NUM>. The dimensions and shapes of removable dental appliance <NUM> may include a position, dimension, and shape of shells and gingival ridges such that removable dental appliance <NUM> is configured to reposition the one or more teeth from their initial positions to final positions when the removable dental appliance is worn by the patient. As discussed above in reference to <FIG>, the position, dimension, and shape of the shells and gingival ridges may affect the magnitude, direction, and length of expression of a force applied to the teeth when the removable dental appliance is worn by the patient. For example, the shape of a respective gingival ridge of a plurality of gingival ridges may determine, at least in part, the magnitude, direction, and length of expression of the force resulting from a deformation of the respective gingival ridge when the removable dental appliance is worn by the patient. The location of a respective gingival ridge relative to a respective shell may also determine, at least in part, the direction of the force that may be transferred from a respective gingival ridge to a respective shell. Also, the location or locations of engagement of a respective shell with a respective tooth determine the direction of the force applied to the respective tooth. Computer <NUM> may analyze at least one of the magnitude, direction, and length of expression of the force resulting from a deformation of the respective gingival ridge when the removable dental appliance is worn by the patient to determine at least one of position, dimension, and shape of a respective gingival ridge that will result in a desired movement of the patient's teeth when the removable dental appliance is worn by the patient.

Computer <NUM> may present a representation of the removable dental appliance <NUM> for the user to review, including review of dimensions and shapes. Alternatively, or additionally, computer <NUM> may accept input from a user to determine dimensions and shapes of a set of removable dental appliances <NUM> for patient <NUM>. For example, the user input may influence at least one of an automatically determined dimensions or shapes. Computer <NUM> may transmit, or otherwise send, a digital model of the set of removable dental appliance <NUM>, the dimensions and shapes of the set of removable dental appliances <NUM>, or both, to computer-aided manufacturing system <NUM> for production of the set of removable dental appliances <NUM>.

Client computing device <NUM> and computer <NUM> are merely conceptual representations of an example computer system. In some examples, the functionalities described with respect to client computing device <NUM>, computer <NUM>, or both may be combined into a single computing device or distributed among multiple computing devices within a computer system. For example, cloud computing may be used for digital design of dental appliances described herein. In one example, the digital representations of tooth structures are received at one computer at the clinic, while a different computer, such as computer <NUM>, is used to determine the shapes and dimensions of a removable dental appliance. In addition, it may not be necessary for that different computer, such as computer <NUM>, to receive all of the same data in order for it to determine shapes and dimensions. Shapes and dimensions may be determined, at least in part, based on knowledge derived through analysis of historical cases or virtual models of exemplary cases, without receiving a complete 3D representation of the case in question. In such an example, data transmitted between client computing device <NUM> and computer <NUM>, or otherwise utilized to design a custom dental appliance may be significantly less than the complete data set representing a complete digital dental model of a patient.

<FIG> is a block diagram illustrating an example computer-aided manufacturing system <NUM> for construction of removable dental appliance <NUM>. In some examples, computer-aided manufacturing system <NUM> may include a 3D printer, a fused deposition modeling device, or the like. Computer-aided manufacturing system <NUM> may include an additive manufacturing system <NUM> in communication with computer <NUM> and coupled to build material source <NUM>. In some examples, computer-aided manufacturing system <NUM> may include computer-aided manufacturing system <NUM> of <FIG>. For example, computer <NUM> may be the same as or substantially similar to computer <NUM>. Build material source <NUM> may include a source of at least one polymeric material, such as, for example, at least one of the polymeric materials of appliance body <NUM> discussed above. Dental appliance <NUM> may be the same as or substantially similar to removable dental appliance <NUM>. In some examples, dental appliance <NUM> may include one dental appliance of the set of dental appliances <NUM>.

Additive manufacturing system <NUM> may include a moveable platform <NUM> and an extrusion head <NUM>. Movable platform <NUM> and extrusion head <NUM> may be configured to manufacture dental appliance <NUM>. For example, computer <NUM> may control extrusion head <NUM> and moveable platform <NUM> to manufacture removable dental appliance <NUM>. Controlling, by computer <NUM>, extrusion head <NUM> may include at least one of controlling a material feed rate from build material source <NUM> to extrusion head <NUM>, controlling a deposition rate of build material on dental appliance <NUM>, controlling a temperature of extrusion head <NUM>, and controlling a position of extrusion head <NUM>. By controlling at least one of a material feed rate, a material deposition rate, a temperature of extrusion head <NUM>, and a position of extrusion head <NUM>, computer <NUM> may control manufacture of a position, dimension, and shape of at least a portion of dental appliance <NUM>. Controlling, by computer <NUM>, movable platform <NUM> may include at least one of controlling a translation of moveable platform in a plane normal to the direction of material deposition from extrusion head <NUM> and controlling an elevation of moveable platform along an axis substantially parallel to the direction of material deposition from extrusion head <NUM>. By controlling at least one of a translation and elevation of moveable platform <NUM>, computer <NUM> may control manufacture of a position, dimension, and shape of at least a portion of dental appliance <NUM>.

Although <FIG> illustrates a computer-aided manufacturing system <NUM> configured for Fused Deposition Modeling (FDM), computer-aided manufacturing system <NUM> may also be configured for stereolithography (SLA), inverse vat polymerization additive manufacturing, inkjet/polyjet additive manufacturing, or other methods of additive manufacturing. In examples in which computer-aided manufacturing system <NUM> is configured for polyjet printing, computer-aided manufacturing system <NUM> may be configured to print multiple materials in a single print, thereby allowing a high modulus material for the rigid components of dental appliance <NUM> (e.g., gingival ridges <NUM>) and a low modulus or elastomeric material for the less rigid components of dental appliance <NUM> (e.g., shells <NUM>). Further, with polyjet additive manufacturing, the modulus may be varied selectively across the dental appliance <NUM>, and a different modulus may be used for the gingival ridge than is used for the shells, for different parts of a gingival ridge, or for different parts of a shell, for example. Similarly, a different modulus may be used for the anchoring shells than is used for the shells used to reposition individual teeth.

<FIG> are flow diagrams illustrating process <NUM> conducted at manufacturing facility <NUM> for construction of the set of removable dental appliances <NUM>. In some examples, set of removable dental appliances <NUM> may include removable dental appliance <NUM>. Computer <NUM> at manufacturing facility <NUM> receives digital dental anatomy data <NUM> including initial positions of one or more teeth of the patient and prescription data <NUM> (<NUM>) from clinic <NUM>. Alternatively, computer <NUM> may retrieve the information from a database located within or otherwise accessible by computer <NUM>. A trained user associated with computer <NUM> may interact with a computerized modeling environment running on computer <NUM> to develop a treatment plan relative to the digital representation of the patient's tooth structure and generate prescription data <NUM>, if clinic <NUM> has not already done so. In other examples, computer <NUM> may automatically develop a treatment plan based solely on the patient's tooth structure and predefined design constraints.

Once computer <NUM> receives patient's tooth structure, computer <NUM> determines dimensions and shapes of a removable dental appliance for the patient (<NUM>). The dimensions and shapes of the removable dental appliance are configured to reposition the one or more teeth of the patient from their initial positions to final positions when the removable dental appliance is worn by the patient. In the same or additional examples, computer <NUM> determines dimensions and shapes of the set of removable dental appliances <NUM> for the patient configured to be worn in series.

In some examples, determining dimensions and shapes of the removable dental appliance includes selecting, with computer <NUM>, the dimensions and shapes of the removable dental appliance according to a set of predefined design constraints. The set of predesigned design constraints may include one or more factors, including, but not limited to, at least one of a minimum and a maximum localized force applied to one or more of the surrounded teeth, at least one of a minimum and a maximum rotational force applied to one or more of the surrounded teeth, at least one of a minimum and a maximum translational force applied to one or more of the surrounded teeth, at least one of a minimum and a maximum total force applied to one or more of the surrounded teeth, and at least one of a minimum and a maximum stress or strain applied to the removable dental appliance, when the removable dental appliance is worn by the patient and the surrounded teeth are in their initial positions. Minimum applied forces are necessary to cause pressure on the periodontal ligament sufficient to result in bone remodeling and tooth movement.

Computer <NUM> may use finite element analysis (FEA) techniques to analyze forces on a patient's teeth as well as the removable dental appliance during the determination of the dimensions and shapes of the removable dental appliance. For example, computer <NUM> 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 a treatment including an ordered set of removable dental appliances. Computer <NUM> may use FEA to select the appropriate removable dental appliance to apply the desired forces on the teeth. In addition, computer <NUM> may use a virtual articulator to determine contact points between the teeth throughout the movement of the modeled teeth during the treatment. Computer <NUM> may further include occlusal contact forces, such as cusp interdigitation forces, in the FEA forces analysis in combination with forces from the removable dental appliance during the design of removable dental appliances in an ordered set of removable dental appliances. Computer <NUM> may further determine an order in which teeth are to be moved to optimize the application of forces, reduce treatment time, improve patient comfort, or the like.

In some examples, determining dimensions and shapes of removable dental appliance <NUM> includes selecting, with computer <NUM> thicknesses of appliance body <NUM>, such as shells <NUM>, and gingival ridges <NUM>, to provide a stiffness suitable to reposition the one or more teeth of the patient from their initial positions to final positions when the removable dental appliance is worn by the patient. In some examples, a thickness of a respective shell of shells <NUM> may range between about <NUM> millimeters and about <NUM> millimeters thick, such as between about <NUM> and about <NUM> millimeters thick, or about <NUM> millimeters thick, whereas a thickness of gingival ridges <NUM> may be between about <NUM> millimeter and about <NUM> millimeters, or between about <NUM> millimeters and about <NUM> millimeter, or between about <NUM> and about <NUM> millimeters, or about <NUM> millimeters. In some examples, computer <NUM> may further select a material of the removable dental appliance, for example, a material as discussed above with respect to removable dental appliance <NUM>, according to the predefined design constraints.

The dimensions and shapes of a removable dental appliance for the patient may be presented to a user via user interface <NUM> of computer <NUM> (<NUM>). In examples in which dimensions and shapes of the removable dental appliance are presented to a user via user interface of <NUM>, the user may have the opportunity to adjust the design constraints or directly adjust the dimensions and shapes of the removable dental appliance before the design data is sent to computer-aided manufacturing system <NUM>. In some examples, the dimensions and shapes of the removable dental appliance may be presented to a user by computer <NUM> directly as the removable dental appliance is manufactured by computer-aided manufacturing system <NUM>. For example, computer <NUM> may send a digital model of removable dental appliance <NUM> to computer-aided manufacturing system <NUM>, and computer-aided manufacturing system <NUM> manufactures removable dental appliance according to the digital model from computer <NUM>.

However, even in examples where the dimensions and shapes of a removable dental appliance for the patient may be presented to a user via user interface of <NUM> of computer <NUM>, following user approval, computer <NUM> sends a digital model of the removable dental appliance to computer-aided manufacturing system <NUM> (<NUM>), and computer-aided manufacturing system <NUM> manufactures removable dental appliance <NUM> of a set of removable dental appliances <NUM> according to the digital model from computer <NUM> (<NUM>). Manufacturing of removable dental appliances <NUM> (<NUM>) may include 3D printing, thermoforming, injection molding, lost wax casting, <NUM>-axis milling, laser cutting, multi-axis robotic Fused Deposition Modeling (FDM), hybrid plastic and metal manufacturing techniques, such as snap-fitting, overmolding, or electroforming, as well as other manufacturing techniques.

In some examples, manufacturing removable dental appliance <NUM> (<NUM>) includes 3D printing removable dental appliance <NUM>. <FIG> is a flow diagram illustrating a technique for 3D printing of a removable dental appliances that include a gingival ridge. As illustrated in <FIG>, 3D printing removable dental appliance <NUM> includes preparing the 3D printer (<NUM>). In some examples, preparing the 3D printer may include selecting and installing (e.g., loading) one or more polymers, one or more binders, or other materials to be printed by the 3D printer. In some examples, preparing the 3D printer may include creating a stage or form onto which the 3D printer will build-up material. Printing removable dental appliance <NUM> also includes building up the material (<NUM>). In some examples, building up material may include inserting materials onto the surface of the removable dental appliance <NUM> (e.g., gingival ridges <NUM> that include metal wires or ribbons) and recommencing building up material. In some examples, 3D printing removable dental appliance <NUM> may include post-processing to remove uncured resin, remove support structures, remove excess material, or to assemble various components, such as adhering a preformed gingival ridge <NUM> to a surface of removable dental appliance <NUM>, or to dispense or build gingival ridge <NUM> directly onto a surface of removable dental appliance <NUM>, which may also be performed in a clinical setting.

In some examples, manufacturing removable dental appliance <NUM> (<NUM>) includes thermoforming removable dental appliance <NUM>. <FIG> is a flow diagram illustrating a technique for thermoforming a removable dental appliances that includes a gingival ridge. As illustrated in <FIG>, thermoforming removable dental appliance <NUM> includes preparing a 3D model of the dentition of the patient (<NUM>). In some examples, the 3D model may include a plaster (stone) model or another representation of the dentition of the patient, such as printed with a 3D printer. The 3D model may include the teeth in a final position of one or more teeth or an intermediate position of one or more teeth (e.g., between the initial position and a final position resulting from the orthodontic treatment). In some examples, the 3D model may include indentations or depressions (e.g., relative to a plane of the teeth) to facilitate forming at least one of the shells and the gingival ridges in the thermoformed and trimmed appliance body. Thermoforming removable dental appliance <NUM> includes thermoforming appliance body <NUM> over the 3D model (<NUM>). In some examples, thermoforming includes placing a polymer sheet onto the 3D model and heating the polymer sheet to cause the polymer sheet to substantially conform (e.g., conform or nearly conform) to the shape of the 3D model. In some examples, thermoforming may use a vacuum to facilitate conformation of the heated polymer sheet to the 3D model. Thermoforming removable dental appliance <NUM> includes trimming excess material from the applicant body to form the shells and the gingival ridges (<NUM>). In some examples, trimming may be performed manually or automated by CNC or robotic machinery such as, e.g., end mill or LASER cutter.

In some examples, both thermoforming and 3D-printing may be used to form different portions of an appliance body. For example, shells <NUM> may be formed by thermoforming, as discussed above, whereas gingival ridges <NUM> may be formed by 3D printing onto the thermoformed shells <NUM>. In some examples, the techniques described with respect to <FIG> may be embodied within a computer-readable storage medium, such as a computer-readable storage medium of computing device <NUM>, computer <NUM>, 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 <FIG>.

The techniques of <FIG> may be applied to design and manufacture of each of an ordered set of removable dental appliances <NUM>. For example, each removable dental appliance in the ordered set of removable dental appliances <NUM> may be configured to incrementally reposition the teeth of the patient. In this manner, the ordered set of removable dental appliances <NUM> may be configured to reposition the teeth of the patient to a greater degree than any one of the removable dental appliances within the set of the removable dental appliances <NUM>. Such an ordered set of removable dental appliances <NUM> may specifically be configured to incrementally reposition the one or more teeth of the patient from their initial positions to final positions as the removable dental appliances of the ordered set of removable dental appliances <NUM> for the patient are worn sequentially by the patient.

<FIG> is a flow diagram <NUM> illustrating successive iterations of treatment using an ordered set of removable dental appliances. The ordered set of removable dental appliances is 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 <NUM>.

Treatment begins with the first iteration of treatment (<NUM>). At the beginning of the first iteration of treatment, the patient's teeth are at their initial positions as represented by detention state X (<NUM>). A scan of the patient's teeth, for example, as described above with respect to <FIG>, are taken to facilitate the design of the ordered set of removable dental appliances (<NUM>). From the scan of patient's teeth, a computer, e.g., computing device <NUM>, determines two different shape and dimensions for removable dental appliances in the ordered set: first setup Xa 608A and second setup Xb 608B. Example techniques for creating a digital model of a patient's teeth are described in <CIT>. The computer may determine first setup Xa 608A and second setup Xb 608B by first adjusting the digital model of the patient's teeth to create a model of the desired position of the patient's teeth following the therapy. Then, the computer may create the shape and dimensions for removable dental appliances in the ordered set based on the time and forces required to move the patient's teeth from the initial positions to their desired positions. For example, the computer model may adjust the thicknesses, positions, shapes, and dimensions of shells and gingival ridge of the removable dental appliances in the ordered set to produce the forces required to move the patient's teeth from the initial positions to their desired positions. The modeled forces applied by removable dental appliances in the ordered set may further be based on the incremental positional movements of the patient's teeth during the treatment. In this manner, the computer may design each of the removable dental appliances in the ordered set according to expected forces applied on the teeth in the predicted positions of the teeth at the time during the treatment the removable dental appliances in the ordered set are to be worn by the patient.

In some examples, at least one, such as three, different removable dental appliances in the set of removable dental appliances can be manufactured using each of first setup Xa 608A and second setup Xb 608B to produce at least two, such as six, removable dental appliances in the set of removable dental appliances. For example, first setup Xa 608A may be used to manufacture first aligner Xa, SOFT 610A, second aligner Xa, MEDIUM 610B, and third aligner Xa, HARD 610C; and second setup Xb 608B may be used to manufacture fourth aligner Xb, SOFT 610D, fifth aligner Xb, MEDIUM 610E, and sixth aligner Xb, HARD 610F. First, second, and third aligners 610A to 610C may be substantially the same shape and dimensions but may include materials with different stiffness characteristics. For example, the second and third aligners 610B and 610C may have higher stiffness characteristics than first aligner 610A, and third aligner 610C may have higher stiffness characteristics than second aligner 610B. Similarly, the fourth, fifth, and sixth aligners 610D to 610F may be substantially the same shape and dimensions but include materials with different stiffness characteristics. In some examples, first aligner 610A may have the same stiffness characteristics as the fourth aligner 610D, such as a relatively soft polymeric material. Similarly, second aligner 610B may have the same stiffness characteristics as the fifth aligner 610E, such as a relatively stiffer polymeric material than first aligner 610A. Likewise, third aligner 610C may have the same stiffness characteristics as the sixth aligner 610F, such as a relatively stiffer polymeric material than second aligner 610B.

Aligners 610A to 610F in the ordered set of removable dental appliances may be worn in sequence over time by the patient. For example, each of aligners 610A to 610F in the ordered set of removable dental appliances may be worn between about <NUM> week and about <NUM> weeks, such as between about <NUM> weeks and about <NUM> weeks, or about <NUM> weeks. Following the treatment plan using aligners 610A to 610F, the patient's teeth may be at their final positions for the first iteration of treatment as represented by detention state X+<NUM> (<NUM>).

Once patient's teeth are at or near dentition state X+<NUM>, the patient may return to the clinician who may evaluate the result of the first iteration of treatment (<NUM>). If the first iteration of treatment has resulted in acceptable final positions of the patient's teeth, then the treatment may be ended (<NUM>). 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 take another scan of the patient's teeth to facilitate the design of a subsequent ordered set of removable dental appliances (<NUM>). In some examples, evaluation of the result of the first iteration of treatment may include taking another scan of the patient's teeth, in which case beginning the next iteration of treatment may simply involve forwarding the digital model of the patient's teeth to a manufacturing facility so that another ordered set of removable dental appliances may be manufactured for the patient based on the new positions of the patient's teeth. In yet other examples, the newly acquired scan may be used to create one or more iterations of removable dental appliances in the clinician's facility.

The techniques of <FIG> represent one specific example, and a variety of modifications may be made to the techniques of <FIG>. For example, an ordered set of removable dental appliances may include more or less than six removable dental appliances. As another example, each removable dental appliance in the ordered set of removable dental appliances may have unique shapes and dimensions, and each removable dental appliance in the ordered set of removable dental appliances may be made of material having substantially the same or similar stiffness characteristics. As another example, each removable dental appliance in the ordered set of removable dental appliances may include a selected thickness, width, height, length, shape, material, or presence of the gingival ridges. For example, first aligner Xa, SOFT 610A, second aligner Xa, MEDIUM 610B, and third aligner Xa, HARD 610C may be a first thickness of the gingival ridge; whereas fourth aligner Xb, SOFT 610D, fifth aligner Xb, MEDIUM 610E, and sixth aligner Xb, HARD 610F may be a second, different thickness of the gingival ridge. 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 selected dimensions of one or more gingival ridge, selected shapes of one or more gingival ridge, or both.

Tests were done to evaluate the effect of a gingival ridge and compare the performance to tooth attachments. <FIG> and <FIG> illustrate an experimental apparatus <NUM> for measuring a force applied to the root of a model first bicuspid by removable dental appliances. A removable dental appliance <NUM> including a gingival ridge formed in the appliance body at the shell of the left first bicuspid and a pocket to receive a tooth attachment bonded to the right first bicuspid was formed. The removable dental appliance <NUM> was thermoformed of <NUM> thick Duran PET-G thermoplastic material. Three-dimensional models of the right first bicuspid 904A (including an attachment) and the left first bicuspid 904B (collectively, tooth models <NUM>), were 3D printed and placed into the respective shells of removable dental appliance <NUM>. Removable dental appliance <NUM> was clamped by clamps 906A and 906B to an angle bracket at the corresponding lateral incisor and at the first molar. The clamps were shaped such that the occlusal surfaces of removable dental appliance <NUM> were held against the angle bracket without applying forces or causing displacement of the labial and lingual surfaces of removable dental appliance <NUM>.

A Lloyd Instruments LF-Plus Digital Testing Machine, available from AMETEK Test & Calibration Instruments, Largo, Florida ("test machine <NUM>"), was used to apply force to the root of the tooth model. Typically, a maximum torque applied to a tooth during orthodontic treatment is about <NUM> Newton-millimeters (N-mm). For tooth models <NUM>, the distance from the center of the labial tooth face to the base of the root was about <NUM>. The maximum force applied to the base of the root was <NUM> N-mm/<NUM> = <NUM> N. Forces were applied to the root of tooth models <NUM> in the mesial, distal, labial and lingual directions. Five consecutive runs were performed for each test to measure forces applied to the root of tooth models <NUM> in the mesial, distal, labial and lingual directions. The measured forces were averaged for the runs. The first run of each test was excluded from the average because of slip between removable dental appliance <NUM> and tooth models <NUM> during some tests. The second and subsequent runs were performed without resetting tooth models <NUM> in removable dental appliance <NUM>.

<FIG> illustrate an average measured force applied to the root of tooth models <NUM> in removable dental appliance <NUM>, including a gingival ridge at the left first bicuspid 904B ("Average Gingival Ridge") and using an attachment on the model right first bicuspid 904A ("Average Attachment"). The displacement values are relative to the point at which the root of tooth models <NUM> is initially contacted in the first test such that the graphs illustrate a relative displacement, rather than an absolute displacement, of tooth model <NUM>. <FIG> illustrates measured force (kilogram, "kg") applied in a distal direction, (e.g., a "distal push") applied to tooth models <NUM> versus displacement (millimeters, "mm") for removable dental appliance <NUM> using an attachment fixed to the model right first bicuspid 904A ("Attachment") and using a gingival ridge at the model left first bicuspid 904B ("Gingival Ridge"). <FIG> illustrates measured force in a labial direction (e.g., a "labial push") applied to tooth models <NUM> versus displacement (mm) for removable dental appliances <NUM> using the Attachment and the Gingival Ridge. <FIG> illustrates measured force in a lingual direction (e.g., a "lingual push") applied to tooth models <NUM> versus displacement (mm) for removable dental appliances <NUM> using the Attachment and the Gingival Ridge. <FIG> illustrates measured force in a mesial direction (e.g., a "mesial push") applied to tooth models <NUM> versus displacement (mm) for removable dental appliances <NUM> using the Attachment and the Gingival Ridge. As indicated by <FIG>, the performance of the removable dental appliance with the gingival ridge (and no tooth attachment) is similar to the performance the removable dental appliance with the tooth attachment.

Claim 1:
A removable dental appliance (<NUM>) comprising:
an appliance body (<NUM>) configured to at least partially surround a plurality of teeth (<NUM>) of a dental arch of a patient (<NUM>), wherein the appliance body (<NUM>) comprises:
a shell (108A-108N) shaped to engage a tooth of the plurality of teeth in an initial position of the tooth; and
a gingival ridge (102A-102D) extending through the appliance body (<NUM>) such that a portion of the gingival ridge is disposed on an exterior surface of the shell and a different portion of the gingival ridge is disposed on an interior surface of the shell, the gingival ridge extending at least from a first interproximal region of the appliance body (<NUM>) at a mesial portion of the shell (108A-108N) along a gingival edge of the shell to a second interproximal region of the appliance body at a distal portion of the shell,
wherein the gingival ridge (102A-102D) is configured to engage a lingual surface (<NUM>) of the tooth (106A) below a height of contour (<NUM>) of the tooth or a labial surface (<NUM>) of the tooth below the height of contour (<NUM>) to enable the appliance body (<NUM>) to apply a force vector at a contact point on the tooth to cause movement of the tooth toward a desired position of the tooth when the removable dental appliance (<NUM>) is worn by the patient, and wherein the gingival ridge (102A) results in a gingival portion of the appliance body (<NUM>) being stiffer than a labial face of the shell or a lingual face of the shell (108A-108N).