ORTHODONTIC APPLIANCES

An aligner including a feature positioned on or in at least one of the buccal sidewall or lingual sidewall of the aligner that is configured to attach to an elastic member. The aligner applies a greater corrective force to a patient's dentition when the elastic member is attached. The feature may include a protrusion in the sidewall with an opening to a space configured to receive and attach to an elastic member hook coupled to the elastic member. The feature may include a through-bore in the sidewall that is configured to receive and attach to the elastic member. The feature may include an add-on hook on the sidewall that is configured to receive and attach to the elastic member. The add-on hook may be positioned on a protrusion in the sidewall. The protrusion may receive and engage with a dental attachment positioned on a surface of a patient's tooth.

TECHNICAL FIELD

The present invention relates generally to the field of orthodontic treatment, and more particularly to orthodontic aligners configured to be used in conjunction with an elastic member.

BACKGROUND

Orthodontics is the practice of manipulating teeth to correct malocclusions between the teeth of the upper and lower dental arches. Typically, treatment of malocclusions includes the use of an orthodontic appliance that applies corrective forces to the teeth. Over time, these corrective forces coerce the teeth to move into their orthodontically correct positions.

Orthodontists may utilize orthodontic appliances referred to as “dental aligners,” or simply “aligners” to move teeth. Aligners are generally supplied as a series of removable appliances that incrementally reposition the patient's teeth from their initial orientation to their orthodontically correct orientation. Patients being treated with aligners can insert and remove the aligners at will, and therefore do not need to visit the orthodontist for adjustments. Rather, when the currently worn aligner has moved the teeth to at or near a final orientation for that aligner, the patient merely begins using the next aligner in the series according to a treatment plan.

To fabricate aligners, the orthodontist may first obtain a 3D computer model of the patient's dentition. This model may be generated, for example, by taking an impression of the dentition and scanning the impression into a computer or using an intraoral scanner to directly image the patient's dentition. Once the 3D computer model has been obtained, the orthodontist determines a target orientation of the teeth that provides a corrected dentition. Alternatively, a software algorithm may automatically generate a target orientation of the teeth in accordance with specific programmed criteria. Multiple computer models may then be generated, with each model representing a 3D positive mold of the patient's teeth corresponding to an incremental orientation of the dentition from an initial orientation to a target orientation. The incremental orientations from initial to target orientations may move the patient's teeth according to a proposed treatment plan. Treatment plans typically include numerous stages of movement from an initial orientation to a target orientation of the teeth. Depending on the degree of tooth movement, treatment plans may include a plurality of aligners that are worn in a predetermined sequence from an initial orientation to a final orientation.

The output of the above-described treatment planning process is a series of 3D positive molds of the patient's teeth represented as a series of digital design files. Once the series of 3D molds has been designed, each aligner is fabricated. Fabrication of the aligners typically involves first printing each positive mold of the patient's teeth using an additive manufacturing method and forming plastic sheets over each mold constructed of target orientations of the dentition according to the computer models. After forming, waste material must be trimmed away to produce the aligner. Trimming may utilize CNC milling or another computer controlled cutting system. Additional post processing steps are also performed during printing of individual dental molds and after forming and trimming of the aligner atop a mold.

Aligners may be configured to be used in conjunction with dental attachments, commonly referred to by Orthodontists as “attachments”. Attachments are solid objects bonded to a tooth, typically using an adhesive, that protrude outwardly from the tooth. When a dental attachment is used, the dental aligner is fabricated to fit tightly over both the attachment and the corresponding tooth such that the forces on the tooth may be increased. The attachment effectively provides an additional contact point between the aligner and the corresponding tooth from which to create force on the tooth. Among many other benefits, this improved force application allows for better control and predictability of tooth movement as well as decreased treatment times. When used in conjunction with aligner treatment, attachments allow more aggressive treatment plans and the correction of more significant and pronounced dental malocclusions.

Aligners may also be configured to be used in conjunction with an elastic member, such as elastic bands. Elastic bands are configured to permit application of an additional corrective force on the jaw of the patient and can be useful in correcting underbite and overbite. Attachment of an elastic band to an aligner is typically achieved by modifying a gingival edge of the aligner to create an attachment point. For example, the gingival edge may be cut in two locations and the elastic member is then looped through the cuts. An intermediate portion of the aligner is bent outward due to the elastic member. Attaching an elastic member at this location can create problems. First, the increased corrective forces applied to the dental aligner by the elastic member adds stress at the location of the attachment point. The added stress is generally the highest at the cuts. Too much stress for too long at these locations can cause the aligner material to deform and prematurely fail, such as by bending, ripping, and/or tearing. When the aligner fails, the patient must replace the aligner. This prolongs treatment time. Second, cutting the gingival edge of the aligner introduces a defect at or near the gingival edge and so reduces the structural integrity of the aligner, potentially making it less effective than it was designed to be. This may also prolong treatment time because the cut aligners may not be capable of moving teeth according to the designed treatment plan.

While generally successful, further improvements in dental aligners and in orthodontic treatment are needed.

SUMMARY

A first embodiment of the present invention is an aligner for use in orthodontic treatment of a patient, comprising a hollow shell and a feature. The hollow shell includes a buccal sidewall, an occlusal wall, and a lingual sidewall and defines a plurality of cavities. The plurality of cavities is configured to receive respective ones of the patient's teeth. The sidewalls define a gingival edge that forms an opening in the hollow shell. The feature is positioned on or in at least one of the sidewalls and is spaced apart from the gingival edge, and is configured to receive an elastic member.

A further embodiment of the present invention is an aligner wherein the feature comprises a protrusion in the at least one sidewall and an opening. The protrusion at least partially defines the cavity and is configured to space the sidewall apart from the patient's tooth. The opening is through the sidewall proximate the protrusion or through the protrusion.

A further embodiment of the present invention is an aligner wherein the feature comprises a through-bore in the sidewall. The through-bore includes an edge that defines a shape. In some embodiments, the edge defines a substantially circular shape. In other embodiments, the edge includes at least one substantially linear portion that is most proximal to the gingival edge and is substantially parallel to the gingival edge. In some further embodiments, the edge defines a substantially polygonal shape.

A embodiment of the present invention is an aligner wherein the feature comprises an add-on hook attached on to the sidewall. The add-on hook includes a projection spaced apart from the sidewall thereby defining a recess between the projection and the sidewall. The add-on hook is fabricated separately from the aligner. In some further embodiments, the sidewall comprises a protrusion on which the add-on hook is attached. In some even further embodiments, the protrusion is configured to engage with a dental attachment on the patient's tooth. In some embodiments, the add-on hook may include a retention bump extending toward the recess that is configured to retain the elastic member. In various embodiments, the projection is curved relative to the sidewall.

A further embodiment of the invention is an aligner wherein the aligner is configured to apply a greater repositioning force than the aligner alone to the respective ones of the patient's teeth or the patient's jaw when an elastic member is attached to the feature.

A further embodiment of the invention is an aligner, wherein the feature comprises at least one of (1) a protrusion in the at least one sidewall that at least partially defines the cavity, the protrusion being configured to space the sidewall apart from the patient's tooth, and an opening through the sidewall proximate the protrusion or through the protrusion; (2) a through-bore in the sidewall, wherein the through-bore includes an edge that defines a shape; and (3) an add-on hook including a projection spaced apart from the sidewall thereby defining a recess between the projection and the sidewall, wherein the add-on hook is fabricated separately from the aligner and is attached on to the sidewall. A further embodiment of the invention is an aligner for use in orthodontic treatment of a patient comprising a hollow shell, a feature, and an elastic member. The hollow shell includes a buccal sidewall, an occlusal wall, and a lingual sidewall and defines a plurality of cavities to receive respective ones of the patient's teeth. The sidewalls define a gingival edge that forms an opening in the hollow shell. The feature is positioned on or in the at least one of the sidewalls and is spaced apart from the gingival edge. The elastic member is configured to attach to the feature. In some embodiments, the elastic member is attached to the feature using a lark's head knot. In various embodiments, the elastic member comprises a hook that attaches the elastic member to the feature. In some further embodiments, the hook includes a retention bump and the feature includes a retention bump receptacle, wherein the retention bump is configured to be received by the retention bump receptacle when the elastic member is attached to the feature by the hook.

DETAILED DESCRIPTION

Embodiments of the invention are directed to an aligner including a feature on or in at least one of a lingual sidewall or a buccal sidewall (also referred to as a labial sidewall herein) at which an elastic member may be attached to the aligner. Advantageously, with the attached elastic, embodiments of the aligner improve the range of forces available for application during orthodontic treatment without sacrificing the structural integrity of the aligner. This is achieved by avoiding modification of a gingival edge of the aligner. The feature that receives the elastic member is spaced apart from the gingival edge and so avoids negatively affecting the structural integrity of the aligner while still providing a location at which an elastic member may be secured. In other words, aligners according to embodiments of the invention lack modification of the gingival facing edge of the aligner during manufacturing or immediately prior to treatment (e.g., by the orthodontist or clinician, such as by cutting the gingival edge with a pair of scissors). An elastic member may be secured to the aligner at the location of the feature and so may be utilized to add specific forces (e.g., translational) to the patient's jaw that would otherwise be unavailable in the absence of the elastic member. This may be achieved without premature failure of the aligner. Application of forces through the elastic are transferred to the aligner at a location and will not degrade the structural integrity of the aligner for the period of use of that aligner. Because each aligner is essentially customized to the patient's teeth in a particular pre-planned orientation, the location at which a feature may be formed may vary according to the forces needed during treatment. In the figures below, exemplary embodiments of the invention are shown in which the feature permits an elastic member to be secured to the aligner.

To these and other ends, referring toFIGS.1-7B, aligners10,11each includes a hollow shell12that is configured to encapsulate a crown of one or more teeth13of a patient's dentition. For each aligner10,11, the shell12is formed with a plurality of cavities14that collectively define a gingival edge16. The gingival edge16defines an opening18in the hollow shell12. Each aligner10,11further includes an occlusal wall20, a buccal sidewall22, and a lingual sidewall24. The shell12may be an elastic material, such as a thermoplastic, in one or more layers. As shown inFIGS.3A,3B, and5-7B, during treatment, aligners10,11are worn on a patient's mandible jaw26and maxillary jaw28, respectively. Referring again toFIGS.1-7B, each cavity14is shaped to receive a specific tooth13on the respective jaw26,28through the opening18. Embodiments of the invention are not limited to use on both mandible and maxillary jaws. Specifically, embodiments of the invention may be worn on the upper jaw, the lower jaw, or both the upper and lower jaw. Any reference to a particular jaw or an aligner to be used with a specific jaw is merely for convenience of description unless stated otherwise.

With further reference toFIGS.1-7B, during orthodontic treatment, each aligner10,11is configured to be selectively positionable over one or more of the patient's teeth13and may fit tightly at least in part due to slight differences in the position of one or more cavities14relative to the corresponding tooth13. A set of aligners (not shown) may include one or more aligners10,11for use in series. Each aligner10,11in the set may differ so that each applies an incremental corrective force to the patient's dentition sufficient to cause movement of one or more of the patient's teeth13through incremental positions from a starting position to an end position. Cumulatively, the individual movements of one or more of a patient's teeth13that results from the use each aligner10,11in series may result in complete treatment of the patient's malocclusion.

With continued reference to the exemplary embodiment shown inFIGS.1-7B, a feature30is located on or in the buccal sidewall22of the aligner10. Although embodiments of the invention shown inFIGS.1-7Bdemonstrate features located on or in the buccal sidewall22, any reference to a feature on or in the buccal sidewall22is merely for convenience of description may be placed on or in the lingual sidewall24. To place the feature30on or in the buccal sidewall22, the doctor or orthodontist first selects a particular tooth13a. Then, the doctor or orthodontist determines the vector of force and amount of movement that they want that tooth13aor the patient's jaw26,28to move. The placement of the feature may be determined based on clinical considerations including, but not limited to, design, structural integrity of the feature30or aligner10, and forces applied to the patient's tooth13aor patient's jaw26(including but not limited to tangential forces). For example, with reference toFIG.3A, the more occlusally offset the feature30is from the gingival edge16, the more tangential force41is created when an elastic40is attached (discussed further below). As shown in the exemplary embodiment ofFIGS.1-3B, the feature30is located on the buccal sidewall22of the cavity14acorresponding to the particular tooth13a. While the feature30forms a portion of the cavity14afor a particular tooth13a, the feature30may be formed on the buccal sidewall22of any single one or multiple cavities14for the remaining teeth13. Embodiments of the invention are not limited to a single feature30on the cavity14aas shown. That is, multiple features30may be formed on or in the buccal sidewall22depending on available space and clinical considerations.

With further reference toFIGS.2-3B, an exemplary feature30includes a buccally extending protrusion32in the buccal sidewall22. The protrusion32forms a portion of the sidewall22but projects outwardly relative to a surrounding portion23of the sidewall22that forms the cavity14a. With this configuration, the protrusion32may appear as a bulge in the sidewall22. The shape of the bulge or the protrusion32does not conform with the surface of the tooth. The protrusion32is formed of the same thickness material as the surrounding portion23but is spaced buccally apart from the tooth surface. This arrangement results in a space34(i.e., gap) being formed between the tooth13aand the protrusion32. As shown inFIGS.3A and3B, an opening36formed through the sidewall22intersects the space34. The opening36in the sidewall22is located proximate a periphery edge37of the protrusion32, such as at a gingival portion of the protrusion32. In such an embodiment, the opening36is therefore positioned between the protrusion32and the edge16of the shell12. In the exemplary embodiment, the opening36is oriented in a substantially labial-lingual direction and so is accessible from the labial direction when the aligner10,11is worn. Embodiments are not limited to the location of the opening36relative to the protrusion32as shown. For example, and although not shown, the opening36may be located substantially on a mesial portion (i.e., positioned between individual cavities), a distal portion (i.e., also positioned between individual cavities), or on an occlusal portion (i.e., between the protrusion32and the occlusal wall20) of the protrusion32.

The protrusion32may be formed in various ways. For example, the protrusion32may be formed by fabricating the aligner10over a mold of a patient's teeth that includes an artificially built-up feature on one or more 3D printed structures in the shape of the desired protrusion32. This can be accomplished by designing a structure on one or more of the 3D modeled teeth in software, which will be printed on the mold of the patient's teeth when the mold is printed using an additive manufacturing method. The result is that when raw aligner material is thermoformed on top of such a mold to form aligner10, the artificially built-up feature will be reflected in the aligner10. Since the designed structure does not reflect an actual part of the patient's tooth, the space34(i.e., a “gap”) will result at the location of the structure when the formed aligner10is worn by the patient. In this way, the protrusion32may have the same thickness as the sidewall22. Another way of forming the protrusion32is to add extra material to the portion of the sidewall22at which the protrusion32is formed. This adds to the through-thickness of the sidewall22. The extra material can be removed from the portion of the sidewall22proximal to the cavity14ato create the space34using a conventional means of removing materials. The placement of the protrusion32may be determined based on clinical considerations including, but not limited to, design and forces applied to the patient's tooth13aor patient's jaw26(including but not limited to tangential forces such as tangential force41shown inFIG.3A). For example, the more occlusally offset the protrusion32is from the gingival edge16, the more tangential force is created when the elastic40is attached. The opening36may be formed in various ways as well. Alternatively, the opening36may be formed by removing a portion of the protrusion32using a conventional means of removing material. Conventional means of removing materials include, but are not limited to, hole punching, drilling, cutting, puncturing, boring, end milling or other similar methods (not shown).

During use and with reference to the exemplary embodiment shown inFIGS.3A and3B, the protrusion32has an internal surface38proximal to the space34and an external surface39opposite from the internal surface38. In the exemplary embodiment, the space34formed by the protrusion32receives a hook42. As shown, the hook42includes a connection44at which the hook42is coupled to the elastic member40. The connection44may be configured to be removably coupled to the elastic40. A portion of the hook42is received by the space34and may contact a portion of the internal surface38. The hook42may not contact the tooth13aduring treatment and, depending on the treatment and material of the hook42, it may be preferable that the hook42not be in a position in which the hook42contacts the tooth13aduring treatment. Another portion of the hook42is in contact with a portion the external surface39of the protrusion32. In this way, the elastic40attaches to the aligner10at the protrusion32via the hook42as shown inFIGS.1-3B. The elastic40may have a closed-loop configuration. The elastic40may be, but is not limited to, an o-ring including a rubber-like elastic polymer or any other continuous band including a suitable rubber-like elastic that can be coupled to the hook42. The elastic member40may not be a continuous band. In some embodiments, a spring may be used in place of the elastic member40shown. It is contemplated that the spring would be capable of creating a tensile force similar to a rubber or rubber-like polymer. The tensile force applied by the elastic member40or other clinical considerations may affect the location the orthodontist chooses to place the feature30. In some embodiments, the feature30or the protrusion32is positioned such that the elastic40is not visible when the aligner10,11is worn by the patient. Advantageously, the hook42is securely attached to the aligner10at a location spaced apart from the gingival edge16of the aligner10. Thus, forces produced by the elastic40when it is elastically stretched, such as when it is stretched and attached at another position in the patient's mouth, are transferred to the sidewall22via the protrusion32and are efficiently and safely distributed to the aligner10. Additionally, the forces produced by the elastic member40are distributed in an area around the protrusion32thereby avoiding subjecting the edge16or any portion thereof to direct loads from the stretched elastic40. In this way, treatment of the patient's malocclusion may be hastened or otherwise improved with a decreased risk premature failure of the aligner10,11at or near the gingival edge16due to the added loading.

With reference toFIG.3B, the hook42may further include a retention bump45and the protrusion32may further include a retention bump receptacle47configured to receive the retention bump45when the hook42is received in opening36of the protrusion32. In such an embodiment, the hook42may be more stably retained in the cavity14awhen the retention bump45is received in the retention bump receptacle47.

Embodiments are not limited to an elastic member40attached to the aligner10at the protrusion32via a hook42. Although not shown, the aligner11may include a protrusion configured to attach to the elastic40as described above. Further, multiple hooks are contemplated. In some such embodiments, the elastic member40is coupled to a plurality of hooks42by which the elastic40may be attached to both aligners10,11at the protrusion32and at a second protrusion respectively as described above. In this way, the elastic member40may be stretched between aligners10,11so that additional forces may be applied to one or more teeth13on both the mandible jaw26and the maxillary jaw28.

Moreover, embodiments are not limited to a single protrusion32per aligner. In that regard, both of the aligners10,11may include a plurality of protrusions32as described above, and each of a plurality of the elastic members40may be attached to a protrusion32on both of the aligners10,11via a plurality of hooks42(not shown). In this way, additional forces may be applied to the patient's jaws26,28. Treatment of the patient's malocclusion may be further hastened or otherwise further improved by the use of the elastic40to apply a greater corrective force to the patient's dentition or additional corrective forces to the patient's dentition as disclosed above.

Referring now toFIGS.4and5, the feature30of the aligner10may include a through-bore60. The through-bore60extends from an external surface66of the sidewall22to an internal surface68of the sidewall22and so opens to the cavity14aconfigured to receive the tooth13a. In such embodiments, no protrusion is formed in the sidewall22, as is shown inFIGS.1-3B. In that regard, the through-bore60receives the elastic member40without the aid of hook42. Therefore, the size of the through-bore60is related to a thickness dimension of the elastic member40. In the exemplary embodiment shown, the through-bore60is a circular hole that is slightly larger than twice the diameter of the elastic member40. The through-bore60may be formed in the aligner10by removing a portion of the sidewall22, including but not limited to hole punching, drilling, cutting, piercing, puncturing, boring, end milling, or other similar methods. Embodiments of the invention are not limited to a single through-bore in an aligner as a plurality of through-bores60may be formed in the aligner10,11.

The size and location of the through-bore60are selected to avoid significant stress at the edge16of the shell12and to allow for the elastic40to attach to the through-bore60(described below). As such, the through-bore is spaced apart from the edge16toward the occlusal wall20. The placement of the through-bore60may be determined using clinical considerations, including but not limited to design, structural integrity of the aligner, and forces applied to the patient's tooth13aor jaw26(including but not limited to tangential forces such as tangential force41shown inFIG.3A) when the elastic40is attached. For example, the more occlusally offset the through-bore60is from the gingival edge16, the more tangential forces are created when the elastic40is attached. The distance of the through-bore60from the gingival edge16of the aligner may be related to the magnitude of the force anticipated to be applied via the elastic member40during treatment. As the anticipated force increases, the through-bore60may be moved further away from the gingival edge16.

The through-bore60includes a through-bore edge62that defines a shape in the sidewall22. As shown, the edge62defines a substantially circular through-bore60. However, embodiments of the invention are not limited to circular through-bores60such as that shown. A portion of the edge62may be substantially parallel to gingival edge16(not shown). In some such embodiments of the invention, the portion of edge62that is substantially parallel to gingival edge16is also the most proximal portion of the through-bore60to edge16(not shown). In that regard, the through-bore edge62may define a polygonal shape such as, but not limited to, a triangular, square, hexagonal, octagonal, or other suitable polygonal shape. Further, the through-bore edge may define an irregular shape, such as a substantially semi-circular shape (not shown). In some further embodiments of the semi-circularly shaped through bore edge, the semi-circular shape resembles a capital letter “D” rotated ninety degrees counterclockwise.

In the exemplary embodiment shown, the elastic member40is tied directly to the aligner10via the through-bore60. As shown, the elastic member40passes through the bore60and is wrapped around the gingival edge16. The elastic40may be a continuous band tied to the aligner10using the lark's head knot (also known as the cow hitch knot). The elastic member40may be tied to the aligner10by looping one end of the elastic band40around edge16, internal surface68, and edge62. Opposing loops in ends of the elastic band40may be tied by pulling one loop (i.e., one end) of the elastic band40through the opposing loop (i.e., the other end) of the elastic band40until the knot is taut. In this way, the elastic40attaches to the aligner10at the through-bore60as shown inFIGS.4and5. Although not shown, other conventional knots for attaching a cord to another object can be used, including but not limited to the reverse lark's head knot, the clove hitch, the constrictor knot, the half-hitch knot, or other similar knots. Embodiments of the invention are not limited to use with elastic members that are continuous bands. By way of example and not limitation, the elastic member40may be a single strand of elastic material that may be tied to the aligner10via the through-bore60. When attached, forces produced by the elastic member40when it is stretched, such as when it is attached to a separate location at another position in the patient's mouth, are transferred to the sidewall22and are efficiently and safely distributed to the aligner10. Moreover, the through-bore60is positioned such that the portion of the edge16where the elastic40applies force has a greater structural strength than conventional aligners that have elastic members attached to a portion of the edge16. Although not shown, the aligner11may include a through-bore configured to attach to the elastic40as described above. The elastic40may therefore be tied to both aligners10,11and be stretched between them so that additional forces may be applied to one or more teeth13on both the mandible jaw26and the maxillary jaw28. In this way, the location, design, and application of the through-bore60allows an elastic40to provide continual application of force during treatment of the patient's malocclusion without subjecting the aligner10,11to force at the gingival edge16sufficient to substantially deform the aligner10,11.

Embodiments of the invention are not limited to the elastic member40being tied to one or both aligners10and11between the through-bore60and the edge16. For example, both the aligners10,11may include a plurality of through-bores60as described above. In this way, a plurality of the elastic members40may be tied to a through-bore60on both aligners10,11. In this way, additional forces may be applied to the patient's jaws26,28. Treatment of the patient's malocclusion may be further hastened or otherwise further improved by the use of an elastic40to apply a greater corrective force to the patient's dentition or additional corrective forces to the patient's dentition as disclosed above.

Referring now toFIGS.6A-6C, in the embodiments shown, the feature30includes a buccally extending protrusion81in the buccal sidewall22in combination with an add-on hook80. As shown, the hook80is attached on to an external surface the buccal protrusion81. The hook80is a separate component that may be attached to the protrusion81using an adhesive selected from a group including, but not limited to, an ultraviolet activated adhesive or a time activated adhesive. In other embodiments, the add-on hook80is a separate component that is welded to the sidewall22using a method including, but not limited to, laser welding. The hook80is formed without penetrations into or through the shell12. The placement of the protrusion81and the hook80may be determined based on clinical considerations including, but not limited to, design and forces applied to the patient's tooth13aor patient's jaw26(including but not limited to tangential forces such as tangential force41shown inFIG.3A). For example, the more occlusally offset the protrusion81and add-on hook80are from the gingival edge16, the more tangential force is created when the elastic40is attached.

A portion of the hook80extends beyond a perimeter of the buccal protrusion81to form at least one projection82. The projection82is therefore a result of a mismatch in position and/or size between the hook80and the protrusion81at the perimeter of buccal protrusion81. The protrusion81extends buccally away relative to surrounding portions of the sidewall22such that the projection82is spaced from the sidewall22to create a recess86. In the exemplary embodiments shown, the projection82extends substantially parallel to the buccal sidewall22from the buccal protrusion81and is pointed in substantially gingival direction (i.e., toward the edge16) from the protrusion81and so is between the edge16and the protrusion81. However, embodiments are not limited to the position shown. For example, the projection82may extend distally, mesially, or occlusally from the protrusion81with the elastic member40being stretched in generally the opposite direction when attached as described below. This ensures that the elastic member40remains securely attached to the aligner10when the elastic member40is stretched during use. In some embodiments, the projection82is curved concavely relative to the buccal sidewall22while the add-on hook is attached to the buccal protrusion81(not shown).

With reference toFIGS.6B and6C, the buccal projection82may include a retention bump85that extends from the projection82toward the recess86. In such embodiments, the retention bump85may be configured to enable secure attachment of the elastic40to the aligner10between the protrusion81and the retention bump85.

With further reference toFIGS.6A-6C, the buccal protrusion81may be formed to engage with a dental attachment84that is bonded to the patient's tooth. In such embodiments, the protrusion81has an internal surface88proximal to the dental attachment84and an external surface89opposite from the internal surface38. The dental attachment84may be bonded to the tooth13aof the patient using a conventional attachment method. In some embodiments, the buccal protrusion81is configured such that the internal surface88comes into contact with the dental attachment84while the aligner10is in use.

With reference toFIG.6C, the add-on hook80may be shaped like a scoop with a handle such that the scoop is configured to cover the protrusion81and handle forms the projection82. As shown in the exemplary embodiment, the attachment84, and consequently the protrusion81, are shaped like hemispheres. The protrusion81and the add-on hook80may be standardized to fit together. This may be accomplished, for example and without limitation, by fabricating the portion of the add-on hook80that covers the protrusion81(i.e., the scoop) to have a relative size and shape configured to receive the protrusion81.

With reference toFIGS.6A-6C, embodiments are not limited to a buccal protrusion81that engages with a dental attachment. For example, the aligner10may include a solid buccal protrusion81(not shown). That is, the portion of the shell12increases in thickness to define the protrusion81.

Although not shown, the protrusion81may be formed in various ways. For example, the protrusion81may be formed by fabricating the aligner10over a mold of a patient's teeth that includes an artificially built-up feature on one or more 3D printed structures in the shape of the desired protrusion81. This can be accomplished by designing a structure on one or more of the 3D modeled teeth in software, which will be printed on the mold of the patient's teeth when the mold is printed using an additive manufacturing method. The result is that when raw aligner material is thermoformed on top of such a mold, the artificially built-up feature will be reflected in the aligner10formed. Since the designed structure is artificial and does not form an actual part of the patient's tooth, a “gap” will result at the location of the structure when the aligner10is applied to the patient's teeth13(i.e., worn by the patient). In this way, the protrusion81may have the same thickness as the sidewall22and the protrusion81may be configured to engage with a dental attachment84. Another way of forming the protrusion81is to add extra material to the portion of the sidewall22at which the protrusion81is formed (not shown). In embodiments where the protrusion81is configured to engage with the dental attachment84, excess material can be removed from the portion of the sidewall22proximal to the cavity14ausing a conventional means of removing materials including, but not limited to, hole punching, drilling, cutting, puncturing, boring, end milling, or other similar methods (not shown).

As shown, the elastic40is attached to the add-on hook80when a portion of the elastic40is received in the recess86and another portion of the elastic40is extended in a direction generally opposite the projection82. Advantageously, the elastic40is securely attached to the hook80at a location spaced-apart from the edge16of the aligner10. Thus, forces produced by the elastic40when it is elastically stretched, such as when it is attached to a separate location at another position in the patient's mouth, are transferred to the sidewall22via the hook80and are efficiently distributed to the aligner10. Additionally, the forces produced by the elastic member40are distributed in an area around the hook80thereby avoiding subjecting the edge16or any portion thereof to direct loads from the stretched elastic40. In this way, treatment of the patient's malocclusion may be hastened or otherwise improved by the use of the elastic40with a decreased risk premature failure of the aligner10,11at or near the gingival edge16due to the added loading.

Embodiments of the invention are not limited to the elastic40being attached to a single add-on hook80of aligner10. Although not shown, the aligner11may include an add-on hook configured to attach to the elastic40as described above. In some such embodiments, the elastic40may be attached to the hook80on aligner10and a second hook on aligner11. In this way, the elastic40may be stretched between aligners10,11so that additional forces may be applied to one or more teeth13on both the mandible jaw26and the maxillary jaw28. Embodiments are not limited to a single add-on hook80per aligner. In that regard, both the aligners10,11may include a plurality of hooks80as described above, and each of a plurality of the elastic members40may be attached to an add-on hook80on both the aligners10,11(not shown). In this way, additional forces may be applied to the patient's jaws. Treatment of the patient's malocclusion may be further hastened or otherwise further improved by the use of an elastic40to apply a greater corrective force to the patient's dentition or additional corrective forces to the patient's dentition as disclosed above.

Referring now toFIGS.7A and7B, in one exemplary embodiment, the feature30of the aligner10may include an add-on hook100on the buccal sidewall22that differs in configuration than the add-on hook80ofFIGS.6A-6C. As shown, the hook100may be attached to the sidewall22at locations without the protrusion32(FIGS.1-3B) or without the protrusion81(FIGS.6A-6C). The hook100has a projection102extending from a main body104. As shown, the body104may attached to the sidewall22at a location spaced apart from the edge16. The add-on hook100may be attached to the aligner10at the sidewall22using an adhesive including, but not limited to, an ultraviolet activated adhesive or a time activated adhesive. In some embodiments, the add-on hook100is welded to the sidewall22using a method including, but not limited to, laser welding. The placement of the hook100may be determined based on clinical considerations including, but not limited to, design and forces applied to the patient's tooth13aor the patient's jaw26(including but not limited to tangential forces such as tangential force41shown inFIG.3A). For example, the more occlusally offset the hook100is from the gingival edge16, the more tangential force is created when the elastic40is attached.

As shown, the projection102extends from the body104so that, in cross-section, the feature30has a dog-legged shape with the projection102extending substantially parallel to the sidewall22. The body104extends buccally away from sidewall22such that the projection102is spaced from the sidewall22to create a recess106. As shown, the projection102extends in a gingival direction. However, embodiments are not limited to the orientation shown. For example, the projection102may extend distally, mesially, or occlusally from the body104with the elastic member40being stretched in generally the opposite direction when attached as described below. Generally, the projection102is positioned on the body104on the same side as the direction in which the body104extends from the shell12. This ensures that the elastic member40remains securely fastened to the aligner10when the elastic member40is stretched during use. In some embodiments, the projection102is curved concavely relative to the sidewall22while the hook100is attached to the shell12(not shown).

With reference toFIG.7B, the projection102may include a retention bump105that extends from the projection102toward the recess106. In such embodiments, the retention bump105may be configured to enable secure attachment of the elastic40to the aligner10between the body104and the retention bump105.

With reference toFIGS.7A and7B, the elastic member40is attached to the hook100with a portion of the elastic40received in the recess106and another portion of the elastic40is extended in a direction generally opposite to the projection102. Advantageously, the elastic40is securely attached to the hook100at a location that is spaced-apart from the edge16of aligner10. Thus, forces produced by the elastic40when it is elastically stretched, such as when it is attached to a separate location at another position in the patient's mouth, are transferred to the sidewall22via the hook100and are efficiently and safely distributed to the aligner10. Additionally, the forces produced by the elastic member40are distributed in an area around the protrusion32thereby avoiding subjecting the edge16or any portion thereof to direct loads from the stretched elastic40. In this way, treatment of the patient's malocclusion may be hastened or otherwise improved by the elastic40with a decreased risk of premature failure of the aligner10,11at or near the gingival edge16due to the added loading.

Embodiments of the invention are not limited to the elastic40being attached to a single add-on hook100of aligner10. Although not shown, the aligner11may include an add-on hook configured to attach to the elastic40as described above. In some such embodiments, the elastic40may be attached to the hook100on aligner10and a second hook on aligner11. In this way, the elastic40may be stretched between aligners10,11so that additional forces may be applied to one or more teeth13on both the mandible jaw26and the maxillary jaw28. Embodiments are not limited to a single add-on hook80per aligner. In that regard, both the aligners10,11may include a plurality of hooks100as described above, and each of a plurality of the elastic members40may be attached to an add-on hook on both the aligners10,11(not shown). In this way, additional forces may be applied to the patient's jaws26,28. Treatment of the patient's malocclusion may be further hastened or otherwise further improved by the use of an elastic40to apply a greater corrective force to the patient's dentition or additional corrective forces to the patient's dentition as disclosed above.

Referring generally toFIGS.1-7B, a pair of aligners10,11may include at least two different types of features30. That is, the orthodontist may mix and match the features30though this may depend on the patient's treatment plan. For example, one feature30, such as that shown inFIGS.1-3B, may be incorporated into the design of the aligner and so be preplanned. If needed and not initially designed, an orthodontist may modify an existing aligner at the office with feature30shown in one ofFIGS.4-7Bso that an elastic member may be utilized during treatment. By way of additional example, the pair of aligners10,11may include the elastic member40that attaches to a first feature30using a hook42as disclosed inFIGS.1-3Band a second feature30as disclosed inFIGS.4and5. As another example, the pair of aligners10,11may include an elastic40that attaches to a first feature30using a hook42as disclosed inFIGS.1-3Band a second feature30as disclosed inFIGS.6A-6C. And, by way of further example, the pair of aligners10,11may include an elastic40that attaches to a first feature30using a hook42as disclosed inFIGS.1-3Band a second feature30as disclosed inFIGS.7A and7B. Treatment of the patient's malocclusion may be hastened or otherwise improved by the use of elastics to apply a greater corrective force to the patient's dentition as disclosed above. Embodiments in which the elastic40is attached to at least two different types of features30disclosed above are not limited to embodiments where the elastic40includes the hook42. Although these embodiments disclosed are not shown, they are readily understood by those skilled in the art as combinations of the elements disclosed above. For example, the pair of aligners10,11may include the elastic member40that attaches to a first feature30as disclosed inFIGS.4and5and a second feature30as disclosed inFIGS.6A-6C. Alternatively, the pair of aligners10,11may include an elastic40that attaches to a first feature30as disclosed inFIGS.4and5and a second feature30as disclosed inFIGS.7A and7B. In some embodiments, the pair of aligners10,11may include an elastic40that attaches to a first feature30as disclosed inFIGS.6A-6Cand a second feature30as disclosed inFIGS.7A and7B. Treatment of the patient's malocclusion may be hastened or otherwise improved by the use of elastics to apply a greater corrective force to the patient's dentition as disclosed above.

With further reference toFIGS.1-7B, embodiments of dental aligners10,11are not limited to one or more feature30on the buccal sidewall22. Aligners10,11according to the present invention may include one or more feature30on the lingual sidewall24(not shown). In such embodiments, the elastic member40may be configured to attach to a feature30on the lingual sidewall24of aligner10and the lingual sidewall24of aligner11. In embodiments with one or more feature30on a lingual sidewall24, the feature30may include one of the following: a projection, similar to projection32shown inFIGS.1-3B, that extends lingually; a through-bore, similar to the through-bore60shown inFIGS.4and5; an add-on hook and a protrusion, similar to the add-on hook80and protrusion81shown inFIGS.6A-6C, where the protrusion extends lingually; and an add-on hook with a body, similar to the add-on hook100with a body104shown inFIGS.7A and7B, where the body extends lingually.