Patent Publication Number: US-2018036623-A1

Title: Sequential sports guard

Description:
BACKGROUND 
     The present invention relates generally to the field of orthodontics, and more particularly to dental positioning appliances and mouth guards that provide protection against impact-induced injuries during a course of orthodontic treatment, as well as related methods and systems. 
     An objective of orthodontics is to move a patient&#39;s teeth to positions where function and/or aesthetics are optimized. Traditionally, appliances such as braces are applied to a patient&#39;s teeth by a treating practitioner and the set of braces exerts continual force on the teeth and gradually urges them toward their intended positions. Over time and with a series of clinical visits and adjustments to the braces, the practitioner adjusts the appliances to move the teeth toward their final destination. 
     More recently, alternatives to conventional orthodontic treatment with traditional affixed appliances (e.g., braces) have become available. For example, systems including a series of preformed appliances/aligners have become commercially available from Align Technology, Inc., Santa Clara, Calif., under the tradename Invisalign® System. The Invisalign® System is described in numerous patents and patent applications assigned to Align Technology, Inc. including, for example in U.S. Pat. Nos. 6,450,807, and 5,975,893, as well as on the company&#39;s website, which is accessible on the World Wide Web (see, e.g., the url “www.invisalign.com”). The Invisalign® System includes designing and/or fabricating multiple, and sometimes all, of the aligners to be worn by the patient before the aligners are administered to the patient and used to reposition the teeth (e.g., at the outset of treatment). Often, designing and planning a customized treatment for a patient makes use of computer-based 3-dimensional planning/design tools, such as Treat™ from Align Technology, Inc. The design of the aligners can rely on computer modeling of a series of planned successive tooth arrangements, and the individual aligners are designed to be worn over the teeth and elastically reposition the teeth to each of the planned tooth arrangements. 
     While recently developed orthodontic treatment technologies, such as those described above, represent a considerable advancement in the field of orthodontics, additional advancements remain of interest. For example, certain individuals may engage in a sporting activity during their orthodontic treatment. In many sports, especially in contact sports such as football, a player typically wears a mouth guard so as to protect the player against impact-induced injuries, including concussion. As such, there is a need for innovative products that provide an orthodontic patient with protection against impact-induced injuries. 
     BRIEF SUMMARY 
     The present disclosure provides protective positioning appliances, accommodating mouth guards, and covering guards that provide an orthodontic patient with protection against impact-induced injuries, and related systems and methods. The disclosed protective appliances, accommodating mouth guards, and covering guards provide the ability to have a patient&#39;s teeth protected while undergoing orthodontic treatment, such with the Invisalign® System. Mouth guards are often used by players of contact sports, such as football. 
     For a fuller understanding of the nature and advantages of the present invention, reference should be made to the ensuing detailed description and accompanying drawings. Other aspects, objects and advantages of the invention will be apparent from the drawings and detailed description that follows. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates a jaw together with an incremental positioning appliance. 
         FIG. 2  illustrates a jaw together with a protective incremental positioning appliance according to an embodiment of the present invention. 
         FIG. 3  illustrates a jaw together with a protective incremental positioning appliance according to another embodiment of the present invention. 
         FIGS. 4A and 4B  are cross-sectional illustrations of teeth received within protective incremental positioning appliances according to embodiments of the present invention. 
         FIG. 5  illustrates a fabrication process that can be used to create upper arch and lower arch protective incremental positioning appliances, accommodating mouth guards, covering guards, and/or accommodating covering guards that have complementary coupling features according to embodiments of the present invention. 
         FIGS. 6A and 6B  are cross-sectional illustrations of teeth received within accommodating mouth guards according to embodiments of the present invention. 
         FIG. 7  is a cross-sectional diagram illustrating the accommodation of a single tooth along a path of intermediate stages according to embodiments of the present invention. 
         FIGS. 8A and 8B  are cross-sectional illustrations of teeth received within incremental positioning appliances that are coupled with covering guards in accordance with embodiments of the present invention. 
         FIGS. 9A and 9B  are cross-sectional illustrations of teeth received within incremental positioning appliances that are coupled with accommodating covering guards in accordance with embodiments of the present invention. 
         FIG. 10  is a simplified block diagram illustrating a system of accommodating mouth guards in accordance with embodiments of the present invention. 
         FIG. 11  is a simplified block diagram illustrating a system of accommodating covering guards in accordance with embodiments of the present invention. 
         FIGS. 12 and 13  are simplified block diagrams illustrating methods for fabricating protective incremental positioning appliances according to embodiments of the present invention. 
         FIGS. 14 and 15  are simplified block diagrams illustrating methods for fabricating accommodating mouth guards according to embodiments of the present invention. 
         FIG. 16  diagrammatically illustrates a system according to an embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     Protective repositioning appliances, accommodating mouth guards, covering guards and accommodating covering guards are provided that protect an orthodontic patient against impact-induced injuries, as well as related systems and methods. In the absence of adequate protection, players of certain contact sports, such as football, may be exposed to a significant risk of impact-induced injuries. The presently disclosed appliances, guards, systems and methods provide a means by which an orthodontic patient can be protected against oral-related impact induced injuries during a course of orthodontic treatment. 
     A protective repositioning appliance can be configured to reposition a patient&#39;s teeth while protecting the patient against impact-induced injuries. Such a protective repositioning appliance can include teeth receiving cavities that are shaped to resiliently reposition a patient&#39;s teeth from a first arrangement towards a second arrangement. A protective repositioning appliance can be further configured to have a shape or material selected to provide protection against impact-induced injury. 
     An accommodating mouth guard can be configured to protect an orthodontic patient&#39;s teeth during a portion of a course of orthodontic treatment, during which the patient&#39;s teeth are repositioned from a first arrangement towards a second arrangement. An accommodating mouth guard can include teeth receiving cavities that are shaped to accommodate a range of positions of the patient&#39;s teeth. A system of accommodating mouth guards can be used to provide protection during multiple stages of orthodontic treatment, where during each stage a patient&#39;s teeth are repositioned by some amount. 
     A covering guard can be configured to couple with at least a portion of a tooth repositioning appliance. The combination of the covering guard and the tooth repositioning appliance can serve to protect the orthodontic patient against impact-induced injuries. An accommodating covering guard can be configured to couple with a sequence of tooth repositioning appliances. 
     Tooth Repositioning Appliances 
       FIG. 1  provides an appropriate starting point in a discussion of the present invention with respect to tooth repositioning appliances designed to apply repositioning forces to teeth. A tooth repositioning appliance  10  can be worn by a patient in order to achieve an incremental repositioning of individual teeth in the jaw  11 . The appliance can include a shell (e.g., polymeric shell) having teeth-receiving cavities that receive and resiliently reposition the teeth. In one embodiment, a polymeric appliance can be formed from a known thin sheet of suitable elastomeric polymeric material, such a 0.03 inch thermal forming dental material by Tru-Tain Plastics, Rochester, Minn. An appliance can fit over all teeth present in an upper or lower jaw, or less than all of the teeth. In some cases, only certain teeth received by an appliance will be repositioned by the appliance while other teeth can provide a base or anchor region for holding the appliance in place as it applies force against the tooth or teeth targeted for repositioning. In some cases, many or most, and even all, of the teeth will be repositioned at some point during treatment. Teeth that are moved can also serve as a base or anchor for holding the appliance as it is worn by the patient. Typically, no wires or other means will be provided for holding an appliance in place over the teeth. In some cases, however, it may be desirable or necessary to provide individual anchors on teeth with corresponding receptacles or apertures in the appliance so that the appliance can apply a selected force on the tooth. Exemplary appliances, including those utilized in the Invisalign® System, are described in numerous patents and patent applications assigned to Align Technology, Inc. including, for example in U.S. Pat. Nos. 6,450,807, and 5,975,893, as well as on the company&#39;s website, which is accessible on the World Wide Web (see, e.g., the url “www.invisalign.com”). 
     An appliance can be designed and/or provided as part of a set or plurality of appliances. In such an embodiment, each appliance may be configured so a tooth-receiving cavity has a geometry corresponding to an intermediate or final tooth arrangement intended for the appliance. The patient&#39;s teeth can be progressively repositioned from an initial tooth arrangement to a target tooth arrangement by placing a series of incremental position adjustment appliances over the patient&#39;s teeth. A target tooth arrangement can be a planned final tooth arrangement selected for the patient&#39;s teeth at the end of all planned orthodontic treatment. Alternatively, a target arrangement can be one of many intermediate arrangements for the patient&#39;s teeth during the course of orthodontic treatment, which may include where surgery is recommended, where inter-proximal reduction (IPR) is appropriate, where a progress check is scheduled, where anchor placement is best, where palatal expansion is desirable, etc. As such, it is understood that a target tooth arrangement can be any planned resulting arrangement for the patient&#39;s teeth that follows one or more incremental repositioning stages. Likewise, an initial tooth arrangement can be any initial arrangement for the patient&#39;s teeth that is followed by one or more incremental repositioning stages. The adjustment appliances can be generated all at the same stage or in sets or batches, e.g., at the beginning of a stage of the treatment, and the patient wears each appliance until the pressure of each appliance on the teeth can no longer be felt or has resulted in the maximum amount of expressed tooth movement for that given stage. A plurality of different appliances (e.g., set) can be designed and even fabricated prior to the patient wearing any appliance of the plurality. After wearing an appliance for an appropriate period of time, the patient replaces the current appliance with the next appliance in the series until no more appliances remain. The appliances are generally not affixed to the teeth and the patient may place and replace the appliances at any time during the procedure (e.g., patient-removable appliances). The final appliance or several appliances in the series may have a geometry or geometries selected to overcorrect the tooth arrangement, i.e., have a geometry which would (if fully achieved) move individual teeth beyond the tooth arrangement which has been selected as the “final.” Such over-correction may be desirable in order to offset potential relapse after the repositioning method has been terminated, i.e., to permit movement of individual teeth back toward their pre-corrected positions. Over-correction may also be beneficial to speed the rate of correction, i.e., by having an appliance with a geometry that is positioned beyond a desired intermediate or final position, the individual teeth will be shifted toward the position at a greater rate. In such cases, the use of an appliance can be terminated before the teeth reach the positions defined by the appliance. 
     Protective Repositioning Appliances 
     Protective dental appliances are provided that reposition a patient&#39;s teeth and provide protection against impact-induced injuries. A protective appliance can include teeth receiving cavities shaped to receive and reposition a patient&#39;s teeth. A protective appliance can have a shape or material selected to provide protection against impact-induced injury. 
     Referring now to  FIG. 2 , an embodiment of a protective repositioning appliance  20  is shown. Similar to the tooth repositioning appliance  10  shown in  FIG. 1 , the protective repositioning appliance  20  includes teeth receiving cavities (hidden from view in  FIG. 2 ) shaped to receive and resiliently reposition a patient&#39;s teeth. In the embodiment shown, the protective appliance  20  includes an optional u-shaped tray  22  for receiving the patient&#39;s opposite jaw teeth when the patient bites down. The u-shaped tray  22  can be defined in part by an occlusal-pad portion  24 , which can be configured so as to exhibit an impact-absorbing compliance during an impact that forces the lower teeth into the upper teeth. The amount of compliance can be influenced by the elasticity and thickness of material used in the occlusal-pad portion. The amount of compliance can also be influenced by the span coverage of the occlusal-pad portion. Additionally, the optional u-shaped tray is partially defined by buccal wall  26  and lingual wall  28 . The buccal wall  26  and lingual wall  28  can serve to laterally couple a plurality of a patient&#39;s upper and lower jaw teeth so as to help protect against lateral impact-induced injuries by distributing localized lateral impacts to surrounding tissues. 
     A protective repositioning appliance  20  can come in a range of variations. For example, an appliance  20  can also be adapted to permit better air flow and breathing while the patient bites down. In the embodiment shown, a plurality of traverse air passages  30  are provided so as to permit the flow of air between buccal and lingual sides of the appliance  20 . A variety of other configurations can also be used to facilitate mouth breathing. For example, one or more regions of the buccal wall  26 , the lingual wall  28 , and/or the occusal-pad portion  24  can be modified so as to provide air passages across the appliance  20 . A protective repositioning appliance  20  can also include provisions for the attachment of a connecting leash, such as the leash tab  32  shown. A connecting leash can be used to couple the appliance with the patient so that it will not get misplaced, such as by attaching the connecting leash to a football helmet or the like. A variety of other configurations may be used to provide for the attachment of a connecting leash, such as loops, sockets, or the like. 
     An appliance can also include a selected color or ornamental design. For example, an appliance can include embedded colors and/or logos, such as for a team or a sponsor. As another example, an appliance can be made with camouflage color for military use. An appliance can also be labeled with personal information, such as the name of the owner, or the number of the owner&#39;s athletic jersey. 
     An appliance can be multi-laminate in composition, such that the different layers of the appliance confer different physical properties. For example, an outer layer can be softer for greater impact protection and an inner layer can be made of harder material for better adaptation to the teeth. An appliance can be tri-laminate, with an outer layer being hard for durability, a middle layer being softer for impact absorption, and an inner layer being hard for better adaptation and retention. 
       FIG. 3  illustrates another protective repositioning appliance  40 , in accordance with an embodiment. Appliance  40  includes a plurality of teeth receiving cavities  42  for the patient&#39;s upper and lower teeth. Appliance  40  can be configured to be an integral unit, or can be configured to include an upper component  44  and a lower component  46 , each of which can include teeth receiving cavities  42 . Where separate upper and lower components are used, they can be configured with complementary interfacing surfaces (not shown in  FIG. 3 ). These complementary interfacing surfaces can serve to laterally couple a plurality of a patient&#39;s upper and lower teeth, thereby helping to distribute localized lateral impacts to surrounding tissues. These complementary surfaces can also provide for snap-fit coupling between the upper component  44  and the lower component  46 . Appliance  40  can also be adapted to facilitate mouth breathing while the patient is biting down, such as by the traverse air passages  48  shown. Additionally, an appliance  40  can be adapted to facilitate mouth breathing in a variety of different ways, such as discussed above with reference to  FIG. 2 . 
       FIGS. 4A and 4B  are cross-sectional illustrations of embodiments of protective repositioning appliances.  FIG. 4A  illustrates a cross-section of an appliance  50  having lower-teeth receiving cavities. The appliance can include an occlusal-pad portion  52  and an optional u-shaped tray  54  for receiving the patient&#39;s upper teeth. As discussed above with reference to  FIG. 2 , the occlusal-pad portion  52  can be configured to exhibit an impact absorbing compliance so as to reduce peak forces transmitted between the patient&#39;s jaws during an impact that forces the lower teeth into the upper teeth, or vice-versa. The optional u-shaped tray  54  can be configured to provide coupling between a plurality of the patient&#39;s upper and lower teeth, so as to distribute localized lateral impact forces to surrounding tissues thereby reducing the level of localized impact forces felt by local tissues. The appliance  50  of  FIG. 4A  can be used to protect a patient against impact-induced injuries while simultaneously subjecting the patient&#39;s lower teeth to resilient repositioning forces. An analogous, but opposite, appliance can be used for to reposition the patient&#39;s upper teeth while providing protection against impact-induced injuries. The appliance  60  of  FIG. 4B  includes an upper component  62  having teeth receiving cavities for the patient&#39;s upper teeth  64 , and a lower component  66  having teeth receiving cavities for the patient&#39;s lower teeth  68 . 
     The upper and lower components can be configured with complementary shaped interfacing surfaces, such as the snap-fit surfaces  70  shown. These complementary-shaped surfaces can provide for lateral coupling between a plurality of the patient&#39;s upper and lower teeth, thereby enhancing the distribution of localized lateral impact forces to surrounding tissues. Various complementary shaped interfacing surfaces can be used. For example,  FIG. 5  illustrates a fabrication process that can be used to create upper arch and lower arch protective incremental positioning appliances, accommodating mouth guards, covering guards, and/or accommodating covering guards that have complementary coupling features. Thin sheets  72 ,  74  of a suitable elastomeric polymeric material can be configured with complementary coupling features, such as ribs on sheet  72  and grooves on sheet  74 , or any other complementary shaped features. Sheet  72  can be formed over a positive mold  76  to form an upper arch component  80  having complementary shaped features disposed on its outer surface. Likewise, sheet  74  can be formed over a positive mold  78  to form a lower arch component  82  having complementary shaped features disposed on its outer surface. When worn by a patient, one or more upper arch component features  84  can interface with one or more lower arch component features  86  so as to provide the above discussed lateral coupling. Components  80 ,  82  can be a protective incremental positioning appliance, an accommodating mouth guard, a covering guard, or an accommodating covering guard. 
     Accommodating Mouth Guards 
     Accommodating mouth guards are provided that can be used during a portion of a course of orthodontic treatment. An accommodating mouth guard can accommodate a range of positions of the patient&#39;s teeth. An accommodating mouth guard may or may not supply any repositioning forces to a patient&#39;s teeth. Instead, an accommodating mouth guard can be used in place of a tooth positioning appliance during a sporting activity. 
     Accommodating mouth guards are provided that can be used during a course of orthodontic treatment. An accommodating mouth guard can include teeth receiving cavities shaped to accommodate a patient&#39;s teeth in a first and a second arrangement. An accommodating mouth guard can have a shape or material selected to provide protection against impact-induced injury. 
       FIGS. 6A and 6B  are cross-sectional illustrations of embodiments of accommodating mouth guards.  FIG. 6A  illustrates a cross-section of an accommodating mouth guard  100  having lower-teeth receiving cavities. Accommodation of a range of positions of the patient&#39;s teeth can be provided in a number of ways. For example, as shown in  FIG. 6A , the teeth receiving cavities can be configured with additional volume selected to accommodate the range of positions. This additional volume provides a cavity of sufficient dimensions to accommodate a tooth in any of the range of positions along the path of possible tooth positions from the initial point to the end point (i.e., the tooth&#39;s swept volume). As another example, the appliance cavity walls can include sufficient compliance so as to be able to deflect a sufficient amount to accept the tooth in any of the range of positions. A combination of additional volume and cavity wall compliance can also be used. As such, it is understood that a tooth receiving cavity can be shaped to accommodate a range of positions for the tooth in a variety of ways, including those discussed above. Additionally, an accommodating mouth guard can include features similar to features of a protective repositioning appliance, such as the occlusal-pad portion  102  and the optional u-shaped tray  104  as shown, and as discussed above with reference to  FIG. 4A . Similarly, the accommodating mouth guard  100  of  FIG. 6A  can be likewise configured for a patient&#39;s upper teeth. 
     Accommodating mouth guards can also be advantageously configured to selectively provide accommodation only for teeth that are being repositioned during a stage of orthodontic treatment. During orthodontic treatment using repositioning appliances, an appliance, or even a series of appliances, may be used to reposition a subset of the patient&#39;s teeth. The remaining teeth may not be repositioned during the stage of treatment. The teeth receiving cavities for non-repositioned teeth can be configured without accommodation, thereby providing for a more secure coupling with the non-moving teeth. This more secure coupling can provide for a more secure coupling between the accommodating mouth guard and the patient&#39;s teeth in general. 
     The accommodating mouth guard  110  of  FIG. 6B  includes an upper component  112  having teeth receiving cavities for the patient&#39;s upper teeth  114 , and a lower component  116  having teeth receiving cavities for the patient&#39;s lower teeth  118 . As discussed above with reference to  FIG. 6A , these teeth receiving cavities can be configured to accommodate a range of positions for any subset of teeth that are being repositioned during a stage of orthodontic treatment, and omit accommodation for any subset of teeth that are not being repositioned during the stage of treatment. Similarly, the upper and lower component can be configured with complementary-shaped interfacing surfaces, such as the snap-fit surfaces  120  shown. These complementary-shaped surfaces can provide for a level of lateral coupling between a plurality of the patient&#39;s upper and lower teeth, thereby enhancing the distribution of localized lateral impact forces to surrounding tissues. 
       FIG. 7  is a simplified cross-sectional diagram of the cavity walls  121  of an accommodating mouth guard and received teeth  122 ,  123 ,  124  that illustrates the accommodation of a single tooth  123  along a path of movement. As can be seen, the cavity walls  121  that surround tooth  123  are configured to accommodate the entire path of the tooth  123  (i.e., the swept volume) for a sequence of positions  125 ,  126 ,  127 . Such accommodation can also be incorporated into an accommodating covering guard. 
     Accommodating mouth guards may also be designed to accommodate orthodontic treatment that is being performed using fixed wire and bracket braces. The accommodation in the mouth guard would allow the mouth guard to fit around both the braces and the archwire, and enable a range of tooth movements to take place for the given time period for which the guard is applicable. The braces treatment plan can be digitally planned out in advance, so that an accommodating mouth guard can be designed to work for a specific portion of the treatment plan. 
     Covering Guards 
     Covering guards are provided that can be coupled with a tooth repositioning appliance so as to provide protection against impact-induced injuries. A covering guard can include a guard segment that covers at least a portion of an appliance. The combination of a guard segment and an appliance can have a shape or material selected to provide protection against impact-induced injury. 
     Covering guards are provided that can be used in combination with a repositioning appliance so as to provide protection against impact-induced injury.  FIG. 8A  is a cross-sectional illustration of a covering guard  130  in accordance with an embodiment. As shown, a covering guard can be coupled with a basic repositioning appliance  132 . A covering guard can be coupled with a repositioning appliance  132  in a variety of ways. For example, the covering guard  130  shown includes repositioning appliance receiving cavities that provide an interface with the underlying repositioning appliance  132 . A covering guard can include a variety of features similar to features discussed above, such as an optional u-shaped tray  134  for receiving teeth from the opposing arch, and an occlusal-pad portion  136 . As discussed above, the optional u-shaped tray  134  can provide for lateral coupling between a plurality of the patient&#39;s upper and lower teeth, thereby helping to distribute localized lateral impact forces to surrounding tissues. The occlusal-pad portion  136  can be configured to provide an impact-absorbing compliance so as to reduce peak forces transmitted between the patient&#39;s arches during an impact that forces the arches together. This reduction of peak transmitted forces can help to reduce the occurrence of impact-induced injuries, such as damage to teeth or concussion. 
       FIG. 8B  is a cross-sectional illustration of a covering guard  140  in accordance with an embodiment. The covering guard  140  includes an upper component  146  adapted to couple with an upper-arch appliance  142 , and a lower component  148  adapted to couple with a lower-arch appliance  144 . As discussed above, a variety of ways can be used to couple the upper and lower components with an underlying repositioning appliance. In the embodiment shown, the upper and lower components have appliance receiving cavities that provide an interface with the underlying repositioning appliance. The upper and lower component can be configured with complementary-shaped interfacing surfaces, such as the snap-fit surfaces  150  shown. Complementary-shaped interfacing surfaces can provide for lateral coupling between a plurality of the patient&#39;s upper and lower teeth, thereby enhancing the distribution of localized lateral impact forces to surrounding tissues. 
     Accommodating Covering Guards 
     Accommodating covering guards are provided that combine characteristics of an accommodating mouth guard and a covering guard. As such, an accommodating covering guard can be configured to interface with a series of underlying repositioning appliances.  FIGS. 9A and 9B  illustrate embodiments of accommodating covering guards  160 ,  170 . Because these accommodating guards share characteristics with the accommodating mouth guards and covering guards discussed above, the above discussion applies and will not be repeated here. 
     Protective Systems 
     Systems are provided that provide protection against impact-induced injuries during a multi-stage orthodontic treatment. An orthodontic treatment stage can include a series of appliances shaped to reposition a patient&#39;s teeth from an arrangement to a subsequent arrangement. A system can include a first accommodating mouth guard for use during a first treatment stage, and a second accommodating mouth guard for use during a second treatment stage. An accommodating mouth guard can include teeth receiving cavities shaped to accommodate a range of positions of a patient&#39;s teeth. An accommodating mouth guard can have a shape or material selected to provide protection against impact-induced injury. A system can include a first accommodating covering guard for use during a first treatment stage, and a second accommodating covering guard for use during a second treatment stage. An accommodating covering guard can be configured to interface with a series of repositioning appliances. 
     A series of two or more of the above discussed protective repositioning appliances, accommodating mouth guards, covering guards, or accommodating covering guards can be used for form a protective system. In the case of protective repositioning appliances or covering guards, the period of use of a particular protective repositioning appliance or covering guard can be generally equivalent to the period of use of an analogous or associated basic repositioning appliance. In the case of accommodating mouth guards or accommodating covering guards, the period of use can be greater that the period of use of an analogous or associated basic repositioning appliance. The period of use for accommodating mouth guards or accommodating covering guards will typically depend on the range of positions accounted for, and the rate that the teeth are being repositioned. 
       FIG. 10  diagrammatically illustrates a system  180  of accommodating mouth guards. The system can include a first accommodating mouth guard  182  that is worn during a first treatment stage during which the patient&#39;s teeth are repositioned from a first arrangement to a second arrangement. The system can include a second accommodating mouth guard  184  that is worn during a second treatment stage during which the patient&#39;s teeth are repositioned from the second arrangement to a third arrangement. The system can also include additional accommodating mouth guards, such as an Nth accommodating mouth guard  186 . Similarly,  FIG. 11  diagrammatically illustrates an analogous system  190  of accommodating covering guards  192 ,  194 , and  196 . 
     Fabrication Methods 
       FIG. 12  diagrammatically illustrates a method  200  that can be used to fabricate of a protective positioning appliance. In step  202 , digital models of teeth-receiving cavities are obtained. These cavities are shaped so that when incorporated into a protective repositioning appliance the appliance exerts resilient forces to the patient&#39;s teeth so as to reposition the patient&#39;s teeth over time. In step  204 , the digital models are used to fabricate a positive mold. The positive mold can be fabricated using a variety of approaches, such as by way of a rapid prototyping machine such as a stereo lithography or digital light projector machine, or also via computer numerical control (CNC) milling. An exemplary rapid prototyping machine is available from 3D System, Valencia, Calif. or EnvisionTEC, Gladbeck, Germany. The rapid prototyping machine can selectively harden a liquid or other non-hardened resin into a three-dimensional structure which can be separated from the remaining non-hardened resin, washed, and used as a positive mold for the appliance. Where such a fabrication method is used, a digital model that includes a negative representation of the teeth-receiving cavities can be prepared from which the positive mold can be fabricated. In step  206 , the appliance if fabricated by forming material over the positive mold. 
       FIG. 13  diagrammatically illustrates a method  210  that can be used to fabricate of a protective positioning appliance having an upper component with upper-teeth receiving cavities, and having a lower component with lower-teeth receiving cavities. In step  212 , digital models of the teeth receiving cavities are received. In step  214 , an upper-positive mold can be fabricated using the digital models for the upper-teeth receiving cavities as discussed above. In step  216 , an upper component is fabricated using the upper-positive mold. In step  218 , a lower-positive mold can be fabricated using the digital models for the lower-teeth receiving cavities as discussed above. In step  220 , a lower component is fabricated using the lower positive mold. In step  222 , the appliance is fabricated using the upper and lower components. 
       FIG. 14  diagrammatically illustrates a method  230  that can be used to fabricate an accommodating mouth guard. In step  232 , digital models of teeth in an initial arrangement are obtained. In step  234 , digital models of teeth in a subsequent arrangement are obtained. The initial arrangement and the subsequent arrangements can be the starting and the ending arrangements for which accommodation is to be provided. In step  236 , the digital models are combined so as to generate an accommodation model that includes geometry that accommodates the positions of the teeth as they move from the initial arrangement to the subsequent arrangement. Intermediate arrangements between the initial arrangement and the subsequent arrangement can also be used in the generation of the accommodation model so as to more accurately accommodate for intermediate positions of the patient&#39;s teeth. A “swept volume” representing the spatial path of each tooth from the beginning to the end within the series can be built in so that the appliance will not interfere with the tooth movement planned during the tooth movement interval for which the guard is designed to accommodate. In step  238 , a positive mold is fabricated by using the accommodation model. The positive mold can be fabricated in a variety of ways, such as by using a rapid prototyping machine as discussed above. In step  240 , the accommodating mouth guard is fabricated using the positive mold. 
       FIG. 15  diagrammatically illustrates a method  250  that can be used to fabricate of an accommodating mouth guard having an upper component with upper-teeth receiving cavities and a lower component with lower-teeth receiving cavities. In step  252 , digital models of teeth in an initial arrangement are obtained. In step  254 , digital models of teeth in a subsequent arrangement are obtained. In step  256 , the digital models are used to generate an accommodation model that includes geometry that accommodates the positions of the teeth as they move from the initial arrangement to the subsequent arrangement. As discussed above, one or more intermediate arrangements can also be used in the formation of the accommodation model so as to more accurately account for intermediate positions of the teeth. In step  258 , a upper-positive mold is fabricated by using the accommodation model. In step  260 , an upper component is fabricated by using the upper-positive mold. In step  262 , a lower-positive mold is fabricated by using the accommodation model. In step  264 , a lower component is fabricated by using the lower-positive mold. In step  266 , the mouth guard is fabricated from the upper and lower components. 
       FIG. 16  is a simplified block diagram of a data processing system  300  embodying the present invention. Data processing system  300  typically includes at least one processor  302  which communicates with a number of peripheral devices via bus subsystem  304 . These peripheral devices typically include a storage subsystem  306  (memory subsystem  308  and file storage subsystem  314 ), a set of user interface input and output devices  318 , and an interface to outside networks  316 , including the public switched telephone network. This interface is shown schematically as “Modems and Network Interface” block  316 , and is coupled to corresponding interface devices in other data processing systems via communication network interface  324 . Data processing system  300  could be a terminal or a low-end personal computer or a high-end personal computer, workstation or mainframe. 
     The user interface input devices typically include a keyboard and may further include a pointing device and a scanner. The pointing device may be an indirect pointing device such as a mouse, trackball, touchpad, or graphics tablet, or a direct pointing device such as a touch screen incorporated into the display. Other types of user interface input devices, such as voice recognition systems, are also possible. 
     User interface output devices typically include a printer and a display subsystem, which includes a display controller and a display device coupled to the controller. The display device may be a cathode ray tube (CRT), a flat-panel device such as a liquid crystal display (LCD), or a projection device. The display subsystem may also provide non-visual display such as audio output. 
     Storage subsystem  306  maintains the basic programming and data constructs that provide the functionality of the present invention. The software modules discussed above are typically stored in storage subsystem  306 . Storage subsystem  306  typically comprises memory subsystem  308  and file storage subsystem  314 . 
     Memory subsystem  308  typically includes a number of memories including a main random access memory (RAM)  310  for storage of instructions and data during program execution and a read only memory (ROM)  312  in which fixed instructions are stored. In the case of Macintosh-compatible personal computers the ROM would include portions of the operating system; in the case of IBM-compatible personal computers, this would include the BIOS (basic input/output system). 
     File storage subsystem  314  provides persistent (non-volatile) storage for program and data files, and typically includes at least one hard disk drive and at least one disk drive (with associated removable media). There may also be other devices such as a CD-ROM drive and optical drives (all with their associated removable media). Additionally, the system may include drives of the type with removable media cartridges. The removable media cartridges may, for example be hard disk cartridges, such as those marketed by Syquest and others, and flexible disk cartridges, such as those marketed by Iomega. One or more of the drives may be located at a remote location, such as in a server on a local area network or at a site on the Internet&#39;s World Wide Web. 
     In this context, the term “bus subsystem” is used generically so as to include any mechanism for letting the various components and subsystems communicate with each other as intended. With the exception of the input devices and the display, the other components need not be at the same physical location. Thus, for example, portions of the file storage system could be connected via various local-area or wide-area network media, including telephone lines. Similarly, the input devices and display need not be at the same location as the processor, although it is anticipated that the present invention will most often be implemented in the context of PCs and workstations. 
     Bus subsystem  304  is shown schematically as a single bus, but a typical system has a number of buses such as a local bus and one or more expansion buses (e.g., ADB, SCSI, ISA, EISA, MCA, NuBus, or PCI), as well as serial and parallel ports. Network connections are usually established through a device such as a network adapter on one of these expansion buses or a modem on a serial port. The client computer may be a desktop system or a portable system. 
     Scanner  320  is responsible for scanning casts of the patient&#39;s teeth obtained either from the patient or from an orthodontist and providing the scanned digital data set information to data processing system  300  for further processing. In a distributed environment, scanner  320  may be located at a remote location and communicate scanned digital data set information to data processing system  300  via network interface  324 . 
     Fabrication machine  322  can encompass a range of fabrication machines and methods used to fabricate positive molds, protective positioning appliances, accommodating mouth guards, or covering guards based on data set information received from data processing system  300 . In a distributed environment, fabrication machine  322  may be located at a remote location and receive data set information from data processing system  300  via network interface  324 . 
     It is understood that the examples and embodiments described herein are for illustrative purposes and that various modifications or changes in light thereof will be suggested to persons skilled in the art and are to be included within the spirit and purview of this application and the scope of the appended claims. Numerous different combinations are possible, and such combinations are considered to be part of the present invention.