Dental aligners having a modified material property and methods and devices for modifying same and treatment methods using same

Abstract

Methods and devices for modifying a material property of an aligner (100) prior to or during orthodontic treatment are disclosed. Orthodontic treatment with modified aligners (100) is disclosed. Elasticity of the aligner material may be modified by a patient. Elasticity of the aligner (100) is changed from an initial value (210) to a second value (220) that is greater or less than the initial value (210). A modulus of the aligner material can be increased or decreased by changing an amount of cross-linking, changing polymerization, or crystallization of the polymer of the material without changing the shape and / or the color of the aligner (100). The modulus of the aligner material is changed after a predetermined amount of anticipated tooth movement is achieved. Modification is achievable by one or more of exposure to specific light wavelengths and intensities, such as UV light or laser light, exposure to heat by which a reaction within the aligner material is achieved.

Description

DENTAL ALIGNERS HAVING A MODIFIED MATERIAL PROPERTY AND METHODS AND DEVICES FOR MODIFYING SAME AND TREATMENT METHODS USING SAMETECHNICAL FIELD

[0001] The present invention relates generally to orthodontic treatment devices, particularly orthodontic aligners, and to methods and to devices for modifying orthodontic treatment devices and their use in orthodontic treatment.BACKGROUND

[0002] In one type of orthodontic treatment, orthodontists address their patient’s malocclusion by moving their patient’s teeth relative to one another. Tooth movement is choreographed or planned so that each tooth may be efficiently moved from an initial configuration, such as a maloccluded position / orientation, into a desired position / orientation in which the functions and aesthetics of the patient’s teeth are improved. To that end, choreographed movement is achieved by an orthodontic treatment plan. The plan is simply a schedule for moving the patient’s teeth from their initial position / orientation to a final, treated position / orientation. A tooth can be moved from its initial position to a desired, final position by applying forces to it. Over time, application of these tooth-moving forces gradually reorient the tooth according to the treatment plan. Application of forces may be by way of orthodontic systems, such as bracket- and- wire systems and aligner systems.

[0003] In bracket-and-wire systems, brackets are bonded to a surface of the tooth, typically with an adhesive. An orthodontic archwire is secured to one or more of the brackets. The shape and stiffness of the archwire as well as the archwire-bracket interaction governs the forces applied to the teeth. By this arrangement, the orthodontist can design a direction and degree of tooth movement.

[0004] In aligner systems, a removable, polymeric shell fits over the patient’s teeth and applies tooth-moving forces to those teeth. The polymeric shell has one or more cavities shaped to receive one or more of the patient’s teeth. An orthodontic treatment plan with aligners often requires a set of aligners. That is, a series of aligners arc designed to take each tooth from aninitial position to a final position according to the treatment plan. For example, there may be 20 stages and so 40 aligners (one for the upper jaw and one for the lower jaw for each stage) required by an orthodontic treatment plan. Each of the aligners defines a stage of tooth movement. For each stage, one aligner is designed to move teeth from one position to a final positions for that stage. These teeth positions for each stage may be intermediate to the initial, untreated position and the final, treated position. Collectively, the stages are designed to treat the patient’s teeth.

[0005] Aligners can offer patients significantly improved aesthetics during treatment. For one, the polymeric shells are often made of a clear polymer, and so are nearly invisible. By contrast, the metallic brackets of brackets-and-wire systems are readily visible on the patient’s teeth. Aligners do not require the orthodontists to bend wires or reposition brackets and are generally more comfortable than orthodontic brackets. However, unlike brackets, aligners may be less effective for treating certain types of malocclusions. For example, extrusion, translation, and certain rotations, can be difficult to achieve with aligners in the absence of an attachment or anchor that is bonded to the tooth. The attachment or anchor provides additional surfaces that the align can engage thereby enlarging the possible tooth movements achievable with aligners.

[0006] During use, the patient typically inserts and removes a pair of aligners for each stage, one for the upper teeth and one for the lower teeth. As the patient couples the aligners to their teeth, the shell is elastically deformed. That is, during insertion, the shell is deformed as it is placed on the patient’s teeth. The deformed aligner applies the tooth-moving forces to the patient’s teeth as the aligner attempts to regain its undeformed condition. Generally, the toothmoving forces are proportional to the amount of deformation in the aligner. As the teeth move under the direction of the deformed aligner, the aligner becomes less deformed. As a result, the tooth-moving forces lessen. The reduction in the tooth-moving forces is difficult to predict. As a consequence, tooth position at the end of each stage is difficult to predict. While the orthodontic treatment plan is designed to move teeth to predetermined positions and orientations, the predetermined positions for one or more teeth are often not actually obtained during one or more stage of the treatment plan.

[0007] For example, aligners are designed to move teeth to specific positions and orientations during each stage of treatment. After a first stage of treatment, the patient’s teeth are intended to be at a first position / orientation. At the first position / orientation, a second stage oftreatment begins with a second set of aligners. After the second stage of treatment, the patient’s teeth arc intended to be at a second position / orientation. A third stage of treatment begins with the teeth at the second position / orientation. This continues for each additional stage of treatment with the next stage of treatment being designed to begin with the teeth at a specific position / orientation achieved with the aligners from the prior stage until the final tooth position / orientation is reached. While this is conceptually simple with each aligner fulfilling its intended, designed tooth movement, problems occur when the teeth do not reach their intended position / orientation in one or more of the stages. That is, there is an error in actual tooth position / orientation relative to the planned tooth position / orientation. That error in position may be propagated through each subsequent stage resulting in the teeth not reaching their final, designed positions. In addition or alternatively, the error can be magnified during subsequent stage or cause movement problems with surrounding teeth.

[0008] With one or more teeth out of position at or near the end of any particular stage, treatment becomes less efficient with the remaining stages. If the error reaches any significant magnitude, further treatment may be impossible. That is, the error in position may inhibit further treatment. For example, if the error in position for a single tooth reaches a significant level, tooth-to-tooth collisions can occur. Once teeth collide, further movement toward their desired positions may be impossible. In any respect, once errors in tooth position / orientation reach a predetermined level, the orthodontist’s intervention is required with the typical result being extended treatment.

[0009] Extending treatment often requires additional aligners to make up for the error in position / orientation or even reverse the tooth position / orientation. And, additional aligners require modified treatment plans and so require more in office time from the orthodontist and the patient. Added treatment time aggravates patients and costs the orthodontist more time and the aligner manufacturer more money for the additional aligners.

[0010] One solution to poor tooth position / orientation control is overcorrection. By overcorrection, aligners are designed to move the teeth more than is actually required. This is a type of designed overshoot of the position / orientation with the concept being that the overshoot position is never actually achieved. Overcorrection is therefore designed to target made-up tooth positions / orientations with the intent that the teeth never actually achieve those positions / orientations. This methodology adds to error in tooth position / orientation, subjects thepatient to higher-than-normal, tooth-moving forces, which can be painful, and reduces predictability by introducing another variable (i.c., the fake tooth position / orientation) in the development of orthodontic treatment plans.

[0011] While generally commercially successful, there are significant drawbacks to current orthodontic treatment with aligners. Thus, improved aligners, methods, and systems are needed.SUMMARY

[0012] The present disclosure is directed to methods and devices for modifying a material property of a dental aligner prior to or during orthodontic treatment and directed to orthodontic treatment with modified aligners. As an example, elasticity of the aligner material may be modified by a patient during treatment. While the invention will be described in connection with certain embodiments, it will be understood that the invention is not limited to those embodiments. On the contrary, the invention includes all alternatives, modifications, and equivalents as may be included within the spirit and scope of the present invention.

[0013] In some aspects, elasticity of the dental aligner is decreased by increasing a modulus of elasticity of the aligner material from an initial value, such as the modulus of elasticity associated with the aligner material after forming the aligner, to a second value that is greater than the initial value. In some arrangements, a modulus of elasticity of the aligner material can be increased by enhancing or increasing an amount of cross-linking, changing polymerization, or crystallization of the polymer of the aligner material without changing the shape and / or the color of the aligner.

[0014] In some aspects, elasticity of the dental aligner is decreased by decreasing a modulus of elasticity of the aligner material from an initial value, such as the modulus of elasticity associated with the aligner material after forming the aligner, to a second value that is less than the initial value. In some arrangements, the modulus of elasticity of the aligner material is decreased by degrading or reducing an amount of cross-linking, changing polymerization, or decrystallization of the polymer of the aligner material without changing the shape and / or the color of the aligner.

[0015] In some arrangements, the modulus of elasticity of the aligner material is increased or decreased after a predetermined amount of anticipated tooth movement is achieved. For example, the modulus of elasticity of the aligner material is increased after the aligner hasbeen used in treatment for one week of a two-week treatment stage, that is, after 50% of a stage is complete. In this way, during a first portion of time of a treatment stage, the modulus of elasticity of the aligner material is an as-formed elastic modulus and then, during a subsequent second portion of the same treatment stage, the modulus of elasticity of the aligner material is greater than the as-formed elastic modulus. As alternative example, the elastic modulus may be less than the as-formed elastic modulus during the second portion of the same treatment stage.

[0016] In some arrangements, the changes in aligner elasticity can be uniformly distributed throughout the aligner material. Stated another way, the modulus of elasticity of the aligner material is uniformly modified. In other arrangements, modification of the modulus of elasticity is localized to a specific region of the dental aligner. In that regard, the aligner consists of regions of as-formed elastic modulus and regions of modified elastic modulus.

[0017] Modification of the elastic modulus of the aligner material is achievable by one or more of exposure to specific light wavelengths and intensities, such as UV light or laser light, exposure to heat by which a reaction within the aligner material is achieved. Reaction may be facilitated by exposure of the aligner to a chemical solution with or without heat or with or without light. The chemical solution may modify molecular bonding or micro structure of the aligner material and thereby modify the modulus of elasticity.BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Embodiments of the present disclosure will now be described hereinafter, by way of example only, with reference to the accompanying drawings in which:

[0019] FIG. 1 depicts the teeth of a patient and a dental aligner that is sized to treat the teeth of the patient.

[0020] FIG. 2 depicts a top view of a patient’s teeth with a dental aligner configured to exert force on the patient’s teeth.

[0021]

[0001] FIG. 3 depicts a schematic representation of a dental aligner applying a force to a tooth.

[0022] FIG. 4A depicts a generalized stress-strain curve for a linearly elastic material and schematically illustrates orthodontic treatment.

[0023] FIG. 4B depicts a generalized stress-strain curve for a linearly elastic material and schematically illustrates orthodontic treatment according to one embodiment of the invention.

[0024] FIG. 5A is a schematic representation of a force relative to displacement of a mass.

[0025] FIG. 5B is a schematic representation of FIG. 5A applied conceptually to orthodontic treatment according to one embodiment of the invention.

[0026] FIG. 6A depicts a dental aligner and an initial stress-strain curve for the dental aligner.

[0027] FIG. 6B shows the dental aligner of FIG. 6A soaking in a soaking solution, according to some aspects of the present disclosure.

[0028] FIG. 6C shows a subsequent stress-strain curve for the dental aligner after the dental aligner of FIG. 6A has undergone the soaking solution of FIG. 6B.

[0029] FIG. 7 illustrates a dental aligner according to some aspects of the present disclosure.DETAILED DESCRIPTION

[0030] Embodiments of the invention are directed to dental aligners, methods, and devices for changing one or more material properties of a dental aligner for use in orthodontic treatment. As an example, the material property of the aligner is modified during orthodontic treatment sometime after the aligner is formed from a sheet of material, such as a sheet of thermoplastic polymer. That is, the aligner may be used at the start of treatment in its as-formed condition and material property. After a period of treatment, a material property of the aligner is modified. The modification of the aligner may be made by the patient or by the orthodontist. The aligner may be modified in the field and not by the aligner manufacture. And, while the material property is modified, the shape and color (typically clear or transparent) of the aligner are not changed. Advantageously, embodiments of the aligners, methods, and devices of the present invention reduce errors in tooth position / orientation and thereby improve accuracy of tooth position / orientation for each stage of treatment. The patient’s orthodontic treatment is more likely to remain on its intended, designed schedule according to a prepared orthodontic treatment plan. Further, reducing tooth position / orientation errors during treatment will require fewer, if any, corrections to the prepared orthodontic treatment plan after manufacturing aligners according to the orthodontic treatment plan.

[0031] To those and other ends and with reference to Fig. 1, a dental aligner 100 is shown according to some aspects of the present disclosure. The dental aligner 100 fits over theteeth 10 of a patient’s jaw 12. Each of the teeth 10 has an occlusal surface 23, a buccal surface 24, a lingual surface 26, and a gingival line 25. Although the upper jaw is not shown, a separate dental aligner may also treat malocclusions on the upper jaw at the same time that the dental aligner 100 treats the lower jaw 12. For the sake of simplicity, a single dental aligner 100 is described. However, embodiments described herein can be applied to each aligner in a series of aligners that are manufactured according to an orthodontic treatment plan. A series of dental aligners may be collectively configured to move a patient’s teeth from an initial, pretreated position / orientation progressively and incrementally through one or more intermediate teeth positions / orientations to a final, desired teeth position / orientation.

[0032] Referring now to Figs. 2 and 3, the aligner 100 is shown coupled to a patient’s jaw. The aligner 100 has an outer surface 110 and an inner surface 120. The inner surface 120 forms one or more cavities 122 that receive one or more of the patient’s teeth 10. A wall or shell 130 may define the outer surface 110 and the inner surface 120 of the aligner 100. In the exemplary aligner 100, the inner surface 120 defines a single, continuous cavity 122 that extends from a rear molar on the left side of the jaw to a rear molar on the right side of the jaw 12, thereby encapsulating all the patient’s teeth 10 on jaw 12. In some embodiments, the aligner 100 can have two or more tooth-receiving cavities 122 that are not in communication with one another. In other words, in the areas where teeth are absent, the aligner 100 can include one or more places where the shell 130 extends transversely across a buccal inner wall 124 and a lingual inner wall 126 of the aligner 100 to separate one cavity from an adjacent cavity.

[0033]

[0002] With reference now to Fig. 3, the tooth 30 is received within the cavity 122 of the aligner 100. Coupling the aligner 100 to the jaw 12 deforms the aligner 100. This is schematically illustrated in Fig. 3. The shell 130 is elastically deformed from a relaxed position 132 (indicated by a dashed line shifted to the right in Fig. 3) to a deformed position 134 (indicated by a solid line shifted to the left in Fig. 3). In the relaxed position 132 (dashed line), the aligner 100 is in a relaxed, undeformed state. Although not shown in Fig. 3, deformation of the aligner 100 may occur in areas of the aligner between adjacent teeth. Accordingly, in Fig. 3, the aligner 100 is shifted from the left (dashed line) to the right (solid line) with the deformation in the shell 130 occurring on each side of the tooth 30. From a different perspective, if the aligner 100 is deformed to the position shown at 134 and the tooth 30 is removed, the elasticallydeformed regions on each side of the tooth 30 would recover and the aligner 100 would regain its undcformcd configuration 132.

[0034] In further detail, the relaxed position 132 is shown for reference purposes in Fig. 3. A macroscopic deformation of the aligner 100 is generally shown by a leftward shift of the aligner 100 (between the phantom line and the solid line 134) in the schematic cross-section shown. By way of example, the aligner 100 is deformed by the position and orientation of the tooth 30. The deformation of the aligner 100 is in another region of the aligner 100 not shown in Fig. 3. That is, the aligner 100 may be bent from its relaxed position 132 to fit the cavity 122 over tooth 30. In the deformed condition, the elasticity of the material of the aligner 100 exerts a tooth-moving force onto a tooth 10 as the aligner 100 attempts to revert to its undeformed condition. As described herein, when deformed, the shell 130 can impart a force onto the tooth 30 inserted into the cavity 122 as the elastically deformed shell 130 attempts to revert to its undeformed condition. This may represent an initial condition of the aligner 100 at the start of a treatment stage. A deformation distance 136 is the difference between the relaxed position 132 and the elastically deformed position 134 and may be at maximum when the aligner 100 is initially coupled to the teeth 10 of jaw 12. The deformation distance 136 may represent the desired movement of the tooth 30 with the aligner 100. By way of example, and not limitation, the deformation distance 136 may be a maximum of 250 pm. Thus, with respect to Fig. 3, the distance between the deformed position 134 and the relaxed position 132 may be as great as 250 pm.

[0035] In the deformed position 134, the aligner 100 imposes tooth moving forces on the tooth 10 as the aligner 100 attempts to recover its relaxed position 132. In Fig. 3, the general force direction is shown by way of arrow 138. In the simple example shown, the aligner 100 may be designed to move the tooth 10 from left to right in the plane of the page in the direction of arrow 138 as the aligner 100 attempts to recover its relaxed position.

[0036] Without being bound by theory, inaccurate repositioning of teeth during orthodontic treatment with the aligner 100 is thought to be due, in part, to a reduction of toothmoving forces as the tooth is moved. For the aligner 100, the tooth-moving force as indicated by arrow 138 are directly related to the material of the aligner and the magnitude of the deformation distance 136 between the tooth’s initial position and the tooth’s final, planned position for each stage. A large distance to be moved will initially produce a proportionallylarge tooth-moving force. However, that force dissipates as the tooth moves according to the treatment plan. In the case of Fig. 3, for example, the force dissipates in the direction of arrow 138. This is because the distance to the final, planned position is less as the tooth 30 moves. So, there is a continuous reduction in tooth-moving forces as the difference between the tooth’s actual position and final position is reduced. With respect to any given stage of treatment, the forces at the start of treatment with the aligner 100 are greater than those at the end of any particular stage of treatment with the aligner 100. In that regard, the magnitude of the force in direction 138 lessens as the tooth 30 moves to the right in Fig. 3. At some point prior to reaching the designed, final position, the tooth-moving forces may be insufficient to move the tooth. This results in an error in the tooth position relative to the designed position according to the treatment plan. As an example, error in tooth position may be in the range of 175 pm (0.175 mm) or less. While not being limited to theory, is believed that an error in position of the tooth from its designed, final position of 25 pm or less is preferred. Biomechanical models theorize a range of minimum threshold forces to move teeth at an acceptable rate, for example, one to 1 mm to 1.5 mm per month. While orthodontic tooth movement depends on magnitude and duration of applied force and variables associated with the particular patient’s anatomy (e.g., number and shape of roots among others) minimum force is believed to be at least 30 gram-force (gf) with optimum force in a range of 50 gf to 150 gf depending on the type of movement (e.g., bodily movement, tipping movement, intrusion, extrusion torquing, uprising, or rotation) desired.

[0037] Embodiments of the invention address this reduction in tooth-moving forces by modifying one or more material properties of the aligner to compensate for a predicted reduction in the tooth-moving force. The tooth-moving forces may therefore be maintained at a predetermined level above that required (e.g., 30 gf) for tooth movement for a larger portion or the entirety of each stage of treatment. That is, the tooth moving forces are maintained for longer period of time above a minimum level. In this way, the tooth-moving forces are more consistent from the start of any tooth movement until the tooth is at or near the desired position / orientation. By maintaining the forces at a more consistent level (i.e., a more constant level above the minimum level) for a longer period of each stage, more accurate tooth positioning is obtained with an aligner at each stage.

[0038] In one embodiment, the material property modified is or relates to a modulus of elasticity of the aligner material. Modulus of elasticity may be thought of as stiffness of thematerial. Increasing the modulus of elasticity of the aligner material increases the stiffness of the aligner. Modulus of elasticity (also referred to as clastic modulus) is a ratio of stress, below a proportional limit, to a corresponding strain. In terms of a stress-strain curve for the aligner material, the modulus of elasticity is a slope of the stress-strain curve in the range of linear proportionality of stress to strain. Increasing the modulus of elasticity, increases the ratio. For a given strain, a proportionally greater stress is produced. This is empirically observed as a stiffer material. As an example, two aligners that are otherwise the same design but with one of a material with a greater elastic modulus than a second one, the aligner having the material of greater elastic modulus (i.e., greater stiffness) will produce proportionally greater tooth-moving forces for the same tooth positions and targeted movement distances. According to embodiments of the invention, modification of the elastic modulus of the material of the aligner during treatment permits more accurate tooth movement. The capability of the aligner to accurately position the teeth is increased. There is thus less error between the actual tooth position / orientation and the designed tooth position / orientation. Tooth movement according to orthodontic treatment plans is therefore more predictable.

[0039] From a perspective of position accuracy, by modification of a material property, such as elastic modulus of one or more aligners in a series of aligners designed according to an orthodontic treatment plan, tooth positioning and / or orientation produced by the one or more aligners is more accurate. The result of the treatment plan is therefore more predictable. As the accuracy increases, error between an actual position / orientation of one or more teeth relative to a designed position / orientation of the one or more teeth at each stage of treatment is reduced. For example, if the error in position / orientation of each tooth is zero at each stage of treatment, the orthodontic treatment plan may be predicted to be completely successful. In that regard, embodiments of the invention do not implement overcorrection and so treatment plans prepared according to embodiments of the invention may not include overcorrection.

[0040]

[0003] As an example and referring to Figs. 4A and 4B, a stress-strain curve 200 of a linearly elastic material for an aligner 100 is shown. By way of example, the aligner 100 may include a thermoplastic polymer. Exemplary thermoplastic polymers include polyethylene (PE), including ultra-high-molecular- weight polyethylene (UHMWPE). Other exemplary materials include polyurethanes that are available from Bay Materials LLC, of Fremont California, a copolyester as a core or monolayer in a multilayered (e.g., three layered) shell. Forthe sake of simplicity, aspects of the present disclosure will he described within the context of an isotropic, linear clastic material. However, the concepts of the present disclosure can be applied to an aligner 100 made from a material that has material properties different from a linear elastic material (e.g., visco-elastic material, non-isotropic material, porous material, and multi-layered material).

[0041] The exemplary stress-strain curve 200 illustrates that for an increase in strain there is a proportional increase in stress in the material along an initial portion of the curve 200. In the exemplary curve, the initial portion of the stress-strain curve 200 is linear’ and as approximated by the dashed line 210. The stress-strain curve 200 of the aligner 100 is an as- formed material property, but it may be modified according to embodiments of the invention. This linear relationship is referred to as Young’s modulus or the elastic modulus 210 of the material. In one embodiment, the modulus of elasticity of the material is as-received by the patient from the aligner manufacturer. In addition, the strain is fully recovered if a load in the linear region, represented by elastic modulus 210, is removed. That is, in the linear region, the material is elastic, and it reverts to its original configuration when the strain / stress is removed. By contrast, plastic deformation can occur at elevated stresses. Plastic deformation may be considered permanent deformation or strain and is not recoverable.

[0042] As applied to the conditions in Fig. 3, when the aligner 100 is deformed to couple it to the patient’s jaw 12, the material is stressed. In the context of the aligner 100, upon insertion of the patient’s teeth, the shell 130 is deformed because the locations of the teeth do not align with the corresponding cavities. At the beginning of a treatment stage, the deformation is at a maximum because the teeth positions are at their maximum displacements, such as distance 136 in Fig. 3, from their targeted position for that stage. For illustrative purposes only, in Fig. 4A, the condition of the maximum deformation is labeled Al for the deformed aligner 100 initially coupled to the patient’s jaw 12. This deformation results in the maximum strain for this region of the aligner 100 and produces a correspondence tooth-moving force Fniaxin the direction of arrow 138 in Fig. 3.

[0043] As the tooth moves under the influence of the force Fmax, the strain in the aligner 100 lessens with time. For illustration purposes only, this is labeled A2 in Fig. 4. That is, the stress and strain of the aligner 100 are each reduced relative to the condition at Al as the tooth 30 is moved to the right in Fig. 3 toward its designed position / orientation. This is represented bythe arrow between A1 and A2. At A2, the tooth-moving force is F2 and is less than Fmax. With the tooth-moving force F2, further tooth movement toward the designed position / orientation of the tooth 30 occurs though movement may be at a slower rate. The final designed position / orientation of the tooth 30 at the end of treatment at this stage is a condition of zero, or near zero, strain in the aligner 100, which occurs at AO. With reference to Fig. 3, zero strain in the aligner 100 is at the relaxed position 132.

[0044] With continued reference to Fig. 4A, the condition of the aligner 100 at A0 may occur when the tooth 30 reaches its designed position / orientation. So, the aligner 100 is unstrained at A0. However, between A2 and A0, the force reduces to a force that is insufficient to move the tooth 30. For illustrative purposes, this is labeled X in Fig. 4. At configuration X, the tooth-moving force drops below a level sufficient to further move the tooth 30. As an example, the tooth-moving force may drop below 30 gf. At this level force, the tooth 30 essentially stops moving or may move but only at a very slow rate. The tooth 30 therefore never reaches its designed position represented by condition A0 in a therapeutically acceptable timeframe. Instead, once the aligner 100 reaches the configuration represented by the strain at X, the tooth 30 remains at a position associated with X. As shown, that position is displaced from the designed position / orientation for that stage. As an example, if the aligner 100 reaches configuration X after one week of treatment of a two-week stage, the tooth remains stationary for the remaining week. An error in position of tooth 30 may then be represented by strain at X orEx.

[0045] With reference to Fig. 4B, in one embodiment of the invention, the patient or the orthodontist may remove the aligner 100 from the patient’s mouth and modify a material property of the aligner 100. By way of example, the material of the aligner 100 may be modified to have an increased elastic modulus as represented by dotted line 220 in Fig. 4B. As is described below, the material of the aligner 100 may be modifiable by soaking the aligner in a chemical solution, by exposure to electromagnetic radiation, or by application of heat or by a combination thereof. The modifications described do not change the shape of the aligner 100 or the clarity of the aligner 100.

[0046] The aligner 100 may be modified one or more times during a single treatment stage. With reference to Fig. 4B, the aligner 100 may be modified at any time before configuration X (i.e., the amount of deformation at which no tooth movement occurs) is reached.In the example, modification may occur a few days into the first week. For example, the aligner 100 may be modified at a configuration B 1 between configurations X and A2. By the modification, the elastic modulus of the material is increased and is represented by dotted line 220. As indicated in Fig. 4, the aligner 100 retains its configuration Bl when it is coupled to the teeth but the modified aligner 100 provides a tooth-moving force F4 that is greater than F3 by virtue of the increased elastic modulus 220. The tooth-moving force F4 may be greater than Fmax depending on the relationship between the elastic modulus 210 and 220. Embodiments of the invention are not limited to F4 being greater than Fmax.

[0047] Based on the elastic modulus 220, the aligner 100 imposes higher tooth-moving forces on the tooth 30 relative to the elastic modulus defined by 210 at configuration Bl even though the amount deformation of the aligner 100 is the same. With time, the deformed distance decreases and so the strain in the aligner 100 is reduced. This is schematically represented by the arrow between Bl and Y. At some strain at Y on the elastic modulus 220, the tooth-moving forces may be insufficient to move the tooth 30. The position of the tooth 30 at Y may be represented by the strain sy. While the tooth 30 may not reach the designed, final position for the treatment stage, which is A0, modification of the elastic modulus at Bl (i.e., from elastic modulus 210 to 220), enables the aligner 100 to move the tooth 30 closer to the designed position at A0, thereby reducing the error in position from that represented by sxto the error in position represented by the ey. The position error may be reduced by a minimum of 50%. For example, if the position error at X is 75 pm and the position error at Y is 30 pm, then the reduction is position error is greater than 50% (i.e., 60%). The modification during the treatment stage is intended to improve the predictability of that stage of the treatment plan with the aligner 100 by reducing the position error.

[0048] Referring to Fig. 4B, in one embodiment, orthodontic treatment during a stage may include modification of the elastic modulus from one value to another, higher value. Advantageously, the net force experienced by the tooth 30 may be at or near Fmax or have an average value greater than the average of forces produced by the elastic modulus 210 alone. While an increase in the modulus of elasticity of the material is shown and described, the material of the aligner 100 may be modified to have a lower modulus of elasticity, such as that represented by line 230 in Fig. 4B. Further, the modulus of elasticity may be modified more than once. For example, at predetermined times during a treatment stage, the aligner 100 may bemodified from elastic modulus 230 to 210 and then to 220 at predetermined times. The reverse relationship is also contemplated.

[0049] With reference to Fig. 5A, a displacement-force schematic is illustrated. A mass 240 is coupled to a spring 242 which is in turn anchored to an immovable object 244. This illustrates a concept of Figs. 4A and 4B in the context of force and displacement as opposed to modulus of elasticity. Displacement of the mass 240 to the right in FIG. 5A elastically extends the spring 242 by an amount 252 from equilibrium 248. This produces a force, Fi, in the direction of arrow 246 toward the immovable object 244 in proportion to a spring constant, ki, multiplied by the displacement, x, at arrow 252. Also shown in FIG. 5A, a displacement of y of the mass 240 indicated at arrow 254 from equilibrium 248 is insufficient to further move the mass 240 toward equilibrium 248. That is, force Fo at ki multiplied by y at 254 is insufficient to produce movement of the mass 240. The resistance to force Fo may be due to friction, for example. Therefore, moving the mass 240 toward equilibrium 248 requires a force greater than the force Fo generated by displacement y at arrow 254 with spring constant ki. One way to achieve movement toward equilibrium 248 at 254 is to change or modify the spring 242 to increase the spring constant, ki, to a new spring constant, I . Increasing the spring constant to k2 increases the force to new force F2 in the direction of arrow 246. To reiterate, forces greater than Fo move the mass 240. Force F2 is greater than Fo so the mass 240 moves. Specifically, at displacement y at 254 with spring constant k2 the modified spring 242 will move the mass toward equilibrium 248.

[0050] Conceptually, the aligner 100 may be analogous to the spring 242 with the tooth 30 being analogous to the mass 240. The patient alveolar bone produces the “friction” to movement. In the analogy, and with reference to FIG. 5B, the aligner 100 will produce a force, F, in proportion to the displacement, x, of the tooth 30 from its designed, targeted position, which in FIG. 5B is 0 on the displacement or X axis. During a first portion of a stage of orthodontic treatment, when the elasticity of the aligner 100 is represented by ki, at displacement xi, the aligner produces a force, Fl. At the displacement y, the force F0 is insufficient to move the tooth 30. Since Fl is greater than F0, the tooth 30 moves towards its designed, targeted position. The first portion of the stage is illustrated by arrow 260. Thus, during the first portion 260 of orthodontic treatment, as the tooth moves, the force is reduced from Fl to F2.

[0051] Before the tooth reaches displacement y and force F0, the aligner 100 is modified. In the example, when the tooth 30 reaches displacement x2 and force F2, the patient may remove the aligner 100 and modify it in accordance with instructions from the orthodontist or from the manufacturer. The aligner 100 is modified to have elasticity represented by k2. The patient then continues to use the aligner 100 in its modified form.

[0052] Since the tooth 30 is at position x2, with the new elasticity k2, the aligner 100 may produce a force of the same or similar magnitude as the force, Fl, observed at displacement xl. The force on the tooth 30 before modification is F2 at displacement x2. After modification, the force is increased to a magnitude similar to that observed at beginning of the stage of treatment, i.e., force Fl. Orthodontic treatment at a second portion of the stage (according to arrow 262), moves the tooth from displacement x2 to displacement x3. As shown, displacement x3 is greater than displacement y. As the tooth moves, the force on the tooth is reduced from Fl to F3. As shown, the force F3 at displacement x3 may be similar to the force F2.

[0053] At displacement x3, the force F3 is greater than F0, but the patient then removes the aligner 100 and modifies it in accordance with instructions from the orthodontist or from the manufacturer. In the example, the aligner 100 is modified to have elasticity represented by k3. The patient then continues to use the modified aligner 100. Since the tooth is at position x3, with the new elasticity k3, the aligner 100 produces a force of the same or similar magnitude as the force, Fl, observed at displacement xl. So, the force on the tooth increases from F3 to Fl.

[0054] Orthodontic treatment at a third portion of the stage (according to arrow 264), moves the tooth from displacement x3 to displacement x4. As shown, displacement x4 is less than displacement y when the force approaches F0, at which no further movement of the tooth is achievable with the aligner 100. So, whereas displacement y represented displacement error of the tooth 30 from its designed targeted position according to elasticity kl, modifying the aligner 100 in accordance with embodiments of the invention may reduce the displacement error to that represented by x4. This may represent a reduction in displacement error of at least 50%.Advantageously, embodiments of the present invention improve the predictability of orthodontic treatment by reducing displacement error.

[0055] As is illustrated, the force on the tooth is adjusted to ensure that the tooth moves during the entirety of the treatment stage with a single aligner without exceeding a force threshold that causes the patient significant pain or causes tissue damage. Moreover, the averageforce is maintained for each of the three portions of the single treatment stage at a level above the forces observed for an aligner without any modification. Because the average force is higher and is maintained for a longer period during the stage, tooth movement is more predictable. Each of the portions of the stage of treatment may be represented by days (e.g., less than a week) where a single stage of treatment lasts two weeks. While FIG. 5B illustrates that the force increases to near F 1 after each modification, embodiments of the invention are not limited to matching an initial force Fl during each or any single subsequent portion of the treatment stage.

[0056] In some multi-aligner systems, the initial aligner may cause patient discomfort due to high forces imparted to the patient’s teeth 10 by the initial aligner 100. In some aspects, the present disclosure provides a dental aligner 100 that can have an initial low elastic modulus that is modified to be more stiff with time. As described herein, decreasing the elastic modulus of the material of the dental aligner 100 over time can minimize or reduce an initial discomfort felt by the patient. In some arrangements, the dental aligner 100 can minimize or reduce bone cell injury by exerting an initial low-magnitude force on the teeth 10 and offsetting the reduction in tooth-moving forces over time by increasing the elastic modulus of the aligner 100.

[0057] Referring to

[0004] Figs. 6A, 6B, and 6C, in one embodiment, a method and a device for altering a material property of an aligner 100 is shown. In Fig. 6A, the aligner 100 can have a first stress-strain function 300 and a first elastic modulus 310. The aligner 100 can be treated to change the first elastic modulus 310 of the aligner 100. In the illustrative example shown in Fig. 5B, the aligner 100 is treated by soaking the aligner 100 in a soaking solution 400. Thus, after a first period of treatment with the aligner 100 have the first elastic modulus 310, the patient or orthodontist may soak the aligner 100 in solution 400. Although not shown, the soaking solution 400 may be in a protective storage case for storing the aligner 100 when not being used. Generally, the patient removes the aligner 100 when eating or drinking anything but water. Thus, the storage case may be filled with solution 400 provided by the orthodontist. When the patient stores the aligner 100, the elastic modulus may be modified.

[0058] In some configurations, the soaking solution 400 can be a solution that is reactive with the material of the aligner 100. The soaking solution 400 can cause a change in the material properties of the aligner 100. For example, the material of the aligner 100 can undergo crosslinking, or polymerization, or depolymerization in the presence of the soaking solution 400. The soaking solution 400 can include an alcohol (e.g., rubbing alcohol), an acidic solution, a basicsolution, or a high-salt solution that degrades the material of the aligner 100. The soaking solution 400 can include a reagent that forms an epoxy with a material of the aligner 100. The soaking solution 400 can be a sugar solution that induces glycation of a material of the aligner 100.

[0059] With reference to Fig. 6C, after a predetermined time, the aligner 100 is removed from the solution 400. The aligner 100 may have a second stress-strain function 320 and a second elastic modulus 330. In the illustrated example of Fig. 6C, the second elastic modulus 330 is steeper (i.e., greater in value) than the first elastic modulus 310, indicating the material of the aligner 100 has become more stiff or less elastic due to treatment with the soaking solution 400. In some arrangements, the aligner 100 and the soaking solution 400 can be configured so that the second elastic modulus 330 can be less than the first elastic modulus 310 following treatment of the aligner 100 with the soaking solution 400, indicating the material of the aligner 100 has become less stiff or more pliable due to treatment with the soaking solution 400.

[0060] Referring now to Fig. 7, in one embodiment, the aligner 100 can include one or more features that enhance the delivery of the soaking solution 400 into the aligner 100. In some arrangements, the aligner 100 can include one or more features that reduce the delivery of the soaking solution 400 into the aligner 100. As depicted in Fig. 6, the outer surface 110 of the aligner 100 can include an unmasked region 140. The unmasked region 140 can be more porous to the soaking solution 400 compared to surrounding regions of the outer surface 110. The unmasked region 140 can enhance infiltration of the soaking solution 400 into the shell 130 adjacent the unmasked region 140. Masking portions of the outer surface 110 and unmasking other portions of the outer surface 110 permits preselected, localized delivery of the soaking solution 400 into the shell 130. Localized delivery of the soaking solution 400 into the shell 130 can enable material properties of portions of the aligner 100 to be changed while other portions of the aligner 100 retain the unmodified material properties of the aligner 100.

[0061] Fig. 7 also depicts other features that can be used as alternatives or additions to localize changes in the elastic modulus of the aligner 100. For example, the aligner 100 can include one or more localized reactive regions 150 that are formed of a material that is reactive or more reactive to the soaking solution 400 compared to surrounding portions of the aligner 100. The reactive regions 150 can be formed in the shell 130, as illustrated in Fig. 6. The reactive regions 150 can be formed of material that weakens or strengthens when exposed to thesoaking solution 400, as described herein. The reactive regions 150 can be disposed within the aligner 100 to selectively alter forces on a tooth 10 in the vicinity of the reactive region 150 upon the elastic modulus of the reactive region 150 changing with treatment of the aligner 100. The reactive region 150 can be disposed near or underneath an unmasked region 140 to enhance delivery of the soaking solution 400 to the reactive region 150.

[0062] As is also shown in Fig. 6, the aligner 100 may alternatively or additionally include one or more fissures or channels 160 formed into the aligner 100. In some arrangements, the channels 160 can be used as conduits that enhance delivery of the soaking solution 400 to the reactive region 150 or to other regions of the aligner 100. In some arrangements, the channels 160 can be formed of or include a material that degrades or stiffens when exposed to the soaking solution 400. In some arrangements, the channels 160 can be used to enhance delivery of the soaking solution 400 to the vicinity of an unmasked region 140. The channels 160 can be openmouth structures that open to the outer surface 110. In some arrangements, the channels 160 can be tube-like structures embedded in the aligner 100 as it is formed. The channels 160 can be arranged as a network or web-like structure that localizes changes in the elastic modulus of the aligner 100 upon the aligner 100 being soaked in the soaking solution 400. The network of channels 160 can be used alone or in combination with the other features disclosed herein to tailor the changes in tooth-moving forces upon the aligner 100 stiffening or degrading upon treatment with the soaking solution 400.

[0063] In one embodiment, a storage case (not shown) for the aligner 100 when not in use may include one or more lights, such as LEDs and / or lasers inside the case, that produce light capable of causing molecular or microstructural changes to the aligner 100 or a portion thereof. For example, LEDs or lasers may produce UV light by which the material of the aligner may begin to crystallize. Periodic exposure of the aligner 100 to one or more wavelengths and / or intensities during any single treatment stage may gradually increase the modulus of elasticity by facilitating crystal growth. As treatment according to that stage progresses, the tooth-moving forces may be maintained at about the same level as Fmax(see Fig. 4).Other Variations and Terminology

[0064] While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of protection. Indeed, the novel methods and systems described herein may be embodied in a variety of other forms. Itwill be understood by those skilled in the art that the present disclosure extends beyond the specifically disclosed embodiments to other alternative embodiments or uses and obvious modifications and equivalents thereof, including embodiments which do not provide all of the features and advantages set forth herein. Furthermore, various omissions, substitutions, and changes in the form of the methods and systems described herein may be made. Those skilled in the art will appreciate that in some embodiments, the actual steps taken in the processes illustrated or disclosed may differ from those shown in the figures. Depending on the embodiment, certain of the steps described above may be removed; others may be added. Accordingly, the scope of the present disclosure is not intended to be limited by the specific disclosures of preferred embodiments herein, and may be defined by claims as presented herein or as presented in the future. The language of the claims is to be interpreted broadly based on the language employed in the claims and not limited to the examples described in the patent specification of during prosecution of the application, which examples are to be construed as non-exclusive.

[0065] Features, materials, characteristics, or groups described in conjunction with a particular aspect, embodiment, or example are to be understood to be applicable to any other aspect, embodiment, or example described herein unless incompatible therewith. All of the features disclosed in this specification (including any accompanying claims, abstract, and drawings), or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features or steps are mutually exclusive. The protection extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract, and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

[0066] Conditional language, such as “can,” “could,” “might,” or “may,” unless specifically stated otherwise, or otherwise understood within the context as used, is generally intended to convey that certain embodiments include, while other embodiments do not include, certain features, elements, or steps. Thus, such conditional language is not generally intended to imply that features, elements, or steps are in any way required for one or more embodiments.The terms “comprising,” “including,” “having,” and the like are synonymous and are used inclusively, in an open-ended fashion, and do not exclude additional elements, features, acts, operations, and so forth. Also, the term “or” is used in its inclusive sense (and not in its exclusivesense) so that when used, for example, to connect a list of elements, the term “or” means one, some, or all of the elements in the list. Further, the term “each,” as used herein, in addition to having its ordinary meaning, can mean any subset of a set of elements to which the term “each” is applied.

[0067] Conjunctive language, such as the phrase “at least one of X, Y, and Z,” unless specifically stated otherwise, is otherwise understood with the context as used in general to convey that an item, term, etc. may be either X, Y, or Z. Thus, such conjunctive language is not generally intended to imply that certain embodiments require the presence of at least one of X, at least one of Y, and at least one of Z.

[0068] Language of degree used herein, such as the terms “approximately,” “about,” “generally,” and “substantially” as used herein represent a value, amount, or characteristic close to the stated value, amount, or characteristic that still performs a desired function or achieves a desired result. For example, the terms “approximately,” “about,” “generally,” and “substantially” may refer to an amount that is within less than 10% of the stated amount. As another example, the terms “generally parallel” and “substantially parallel” may refer to a value, amount, or characteristic that departs from exactly parallel by less than 15 degrees.

[0069] While the present invention has been illustrated by a description of various embodiments and while these embodiments have been described in some detail, it is not the intention of the inventors to restrict or in any way limit the scope of the appended claims to such detail. Thus, additional advantages and modifications will readily appear to those of ordinary skill in the art. The various features of the invention may be used alone or in any combination depending on the needs and preferences of the user.

[0070] What is claimed is:

Claims

1. A method of altering a material property of an aligner, the method comprising: providing an aligner comprising a polymer having a first elastic modulus; soaking the aligner in a soaking solution, the soaking solution configured to interact with the polymer to form a treated polymer having a second elastic modulus, the second elastic modulus being different from the first elastic modulus; and removing the aligner from the soaking solution after the second elastic modulus has been achieved.

2. The method of claim 1 wherein soaking occurs after a portion of one stage of orthodontic treatment with the aligner is completed.

3. The method of claim 1 or claim 2 wherein the first elastic modulus is of the polymer following forming of the aligner.

4. A method of orthodontic treatment of a patient with an aligner comprising: using the aligner to move at least one of the patient’s teeth; after moving the at least one of the patient’ s teeth, (i) modifying the aligner to change an elastic property of the aligner; and after modifying the aligner, (ii) using the aligner to further move the at least one of the patient’s teeth.

5. The method of claim 4, further comprising: repeating (i) and (ii) at least once for the at least one of the patient’s teeth.

6. A dental aligner comprising: a shell comprising a polymer, wherein an elastic modulus of the polymer has a first value at one region of the shell and a second value at another region of the shell, the first value being different from the second value.

7. The dental aligner of claim 6, wherein the shell includes one or more channels therein.

8. A dental aligner comprising: a shell comprising a polymer, wherein the shell includes one or more channels therein.

9. The dental aligner of claim 8, wherein the channels are tube-like structures embedded in the shell.

10. The dental aligner of claim 8 or claim 9, wherein the channels are arranged as a network or web-like structure.

11. A storage case for storing aligners having one or more of an LED and a laser housed therein.

12. A dental aligner having modified material property as described herein.

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