Abstract:
Provided are orthodontic corrector devices, related assemblies and methods which direct forces within the oral cavity. These corrector devices and assemblies include a flexible cantilever which is coupled to both a connector component and a force module. The cantilever acts to isolate adjacent components from mastication forces encountered during treatment. By resiliently deflecting in response to these inadvertent forces, the cantilever reduces the likelihood of device breakage and bond failure. Upon removal of these forces, the cantilever returns to its original orientation thereby maintaining the proper alignment of the corrector. Advantageously, the cantilever also allows the force module to be positioned further in the distal direction thereby enabling a greater range of connection options.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    Orthodontic devices, assemblies and methods are provided for use in orthodontic treatment. More particularly, orthodontic corrector devices, along with related assemblies and methods, are provided for directing therapeutic forces between dental structures within the oral cavity. 
         [0003]    2. Description of the Related Art 
         [0004]    The field of orthodontics relates to the supervision, guidance and correction of teeth towards proper positions in the oral cavity. Orthodontic therapy generally involves the application of forces to move teeth into a proper bite configuration, or occlusion. One mode of therapy, known as fixed appliance treatment, is carried out using a set of tiny slotted appliances called brackets, which are affixed to the anterior, cuspid, and bicuspid teeth of a patient. In the beginning of treatment, a resilient orthodontic appliance known as an archwire is received in each of the bracket slots. The end sections of the archwire are typically anchored in appliances called buccal tubes, which are affixed to the patient&#39;s molar teeth. 
         [0005]    When initially installed in the brackets and buccal tubes, the archwire is deflected from its original arcuate (or curved) shape, but then gradually returns to this shape during treatment. In this manner, the archwire applies gentle, therapeutic forces to move the teeth from improper positions to proper positions. Taken together, the brackets, buccal tubes, and archwire are commonly referred to as “braces”. Braces are often prescribed to improve dental and facial aesthetics, bite function and dental hygiene. 
         [0006]    During certain stages of treatment, additional intraoral appliances may be prescribed for use in conjunction with fixed appliances to correct particular kinds of malocclusions. For example, some appliances are used to correct Class II malocclusions, such as an overbite where the mandibular first molars are located excessively distal (in the rearward direction) with respect to the maxillary first molars when the jaws are closed. Other appliances remedy an opposite malocclusion, known as a Class III malocclusion, such as an underbite where mandibular first molars are located excessively mesial (in the forward direction) with respect to the maxillary first molars when the jaws are closed. 
         [0007]    In recent years, Class II and Class III correctors have been developed that are installed by the orthodontist and require minimal patient intervention during the course of treatment. These devices advantageously correct Class II and Class III malocclusions without need for patient compliance. Moreover, there are various possibilities in connecting these devices to the dental arch. Banded headgear tubes are still commonly used to provide a distal connection to the upper dental arch. These banded appliances, however, are not universally used. Bondable molar appliances are more convenient to use in many respects and some orthodontists prefer them over banded appliances. As another option, connection to the dental arch may be made indirectly by coupling the intraoral device to one or both archwires. Accordingly, manufacturers have sought to configure these intraoral devices with the versatility to work with a wide variety of appliances. 
       BRIEF SUMMARY OF THE INVENTION 
       [0008]    Provided herein is an intraoral orthodontic corrector, along with related assemblies and methods, that direct corrective forces to dental structures while displaying substantially improved robustness during the course of treatment. 
         [0009]    While prior art devices have attempted to connect intraoral appliances to bonded appliances, these efforts often exposed their vulnerabilities to breakage or bond failure as a result of mastication (biting) forces inadvertently transmitted to the appliance. The risk of bond failure is also generally higher in these situations since bonded appliances tend to be significantly weaker than their banded counterparts. Moreover, these prior art devices tend to use couplings that provide a high degree of pivotal freedom between adjacent components. While these couplings advantageously allow normal jaw movement by the patient, these same couplings can also be problematic in at least two other ways. 
         [0010]    First, the freedom provided by the coupling can allow portions of the device to inadvertently pivot into the occlusal areas. This, in turn, can result in the patient biting down on the device thereby causing bond failure, device breakage and/or painful contact of the device with the oral tissues of the patient. Second, even if the device is kept safely away from the occlusion, the couplings can still bind or jam when misaligned or otherwise knocked out of position by hard food objects and the like. When this occurs, the biting force can become transmitted directly to the coupling and again cause device breakage or bond failure. 
         [0011]    The provided orthodontic corrector overcomes these problems by including a flexible cantilever that isolates adjoining device components from the brunt of these biting forces. By resiliently flexing, or deflecting, in response to inadvertent forces placed on the device, vulnerable components of the device are protected. When these forces are subsequently removed, the cantilever returns to its original orientation and thereby maintains the proper alignment of the corrector. As an additional advantage, the cantilever can allow the position of the force module to be extended toward the distal direction and enable a greater range of connection options between the force module and the dental arch. 
         [0012]    In one aspect, the present invention is directed to an orthodontic corrector for applying therapeutic forces between an upper arch appliance and a lower arch appliance comprising a connector for coupling to the upper arch appliance of a patient, a cantilever rigidly coupled to the connector, the cantilever comprising a resilient material having sufficient memory to self-return the cantilever to a certain, pre-determined orientation when relaxed, and a force module having two opposing ends, with one end coupled to the cantilever and the opposite end adapted for coupling to the lower appliance. 
         [0013]    In another aspect, the invention is directed to an orthodontic assembly comprising a set of brackets, an archwire connected to the brackets, a connector coupled to the archwire, a cantilever rigidly coupled to the connector and comprising a resilient material having sufficient memory to self-return the cantilever to a certain, pre-determined orientation when relaxed, and a force module coupled to the cantilever. 
         [0014]    In still another aspect, the invention is directed to a method of applying forces between first and second orthodontic appliances located on opposing jaws of a patient comprising providing a connector, the connector rigidly attached to one end of a cantilever comprising a resilient material having sufficient memory to self-return the cantilever to a certain, pre-determined orientation when relaxed, the other end of the cantilever being pivotally attached to a force module, coupling the connector to the first appliance, and coupling the force module to the second appliance, wherein the cantilever flexibly maintains at least a portion of the force module in a location that is fixed relative to the connector. 
       DEFINITIONS 
       [0015]    As used herein: 
         [0016]    “Mesial” means in a direction toward the center of the patient&#39;s curved dental arch; 
         [0017]    “Distal” means in a direction away from the center of the patient&#39;s curved dental arch; 
         [0018]    “Occlusal” means in a direction toward the outer tips of the patient&#39;s teeth; 
         [0019]    “Gingival” means in a direction toward the patient&#39;s gums or gingiva; 
         [0020]    “Facial” means in a direction toward the patient&#39;s lips or cheeks; 
         [0021]    “Lingual” means in a direction toward the patient&#39;s tongue. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         [0022]      FIG. 1  is a side view of an orthodontic assembly according to one embodiment of the invention installed on a dental arch; 
           [0023]      FIG. 2  is an exploded facial view looking at the lingual side of an orthodontic corrector shown in the assembly of  FIG. 1 ; 
           [0024]      FIG. 3  is an enlarged facial view looking at the lingual side of a connector shown in  FIG. 2  except that the connector is shown in an orientation as it appears before assembly to a cantilever of the corrector; 
           [0025]      FIG. 4  is a mesial view of the connector in  FIG. 3 ; 
           [0026]      FIG. 5  is a gingival view of the connector in  FIGS. 3 and 4 ; 
           [0027]      FIG. 6  is a reduced fragmentary gingival view of the orthodontic corrector in  FIG. 2 ; 
           [0028]      FIG. 7  is a view somewhat similar to  FIG. 4  except that the connector is shown as it appears when assembled to the cantilever of  FIG. 3 ; 
           [0029]      FIG. 8  is an exploded facial view of an orthodontic corrector according to another embodiment of the invention; 
           [0030]      FIG. 9  is an enlarged mesial view of a connector shown in the corrector of  FIG. 8 ; 
           [0031]      FIG. 10  is a fragmentary gingival view of the orthodontic corrector in  FIG. 8 ; 
           [0032]      FIG. 11  is mesial view of the orthodontic corrector in  FIGS. 8 and 10 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0033]    The present disclosure relates to orthodontic devices, correctors, and assemblies that apply therapeutic forces to dental structures during the course of treatment. Exemplary embodiments of these devices, correctors, and assemblies shown herein are useful for treatment of Class II malocclusions. However, these should not be deemed to unduly limit the invention. For example, these embodiments could also be adapted for use in treating class III malocclusions. Alternatively, these embodiments could be adapted for use within either the upper or lower arch individually. 
         [0034]      FIG. 1  depicts an orthodontic assembly according to one exemplary embodiment, broadly designated by the numeral  100 . The assembly  100  represents the combination of orthodontic appliances installed on the right side of the upper and lower dental arches of a patient as shown. Located on the upper dental arch are a set of teeth, including upper anteriors  10 , upper cuspid  12 , upper bicuspids  14 , upper first molar  16 , and upper second molar  18 . Similarly, the lower arch shows a set of teeth including lower anteriors  20 , lower cuspid  22 , lower bicuspids  24 , and lower molars  26 . 
         [0035]    Bonded orthodontic appliances are affixed to the respective teeth of both the upper and lower arches. Appliances attached to the upper arch include upper brackets  30  and upper buccal tube  32 . Similarly, appliances attached to the lower arch include lower brackets  40  and lower buccal tube  42 . As shown in  FIG. 1 , each bracket and buccal tube includes a base for bonding the appliance to the facial surface of its respective tooth. As shown, each bracket further includes a slot for receiving an archwire with an opening oriented towards the facial direction. 
         [0036]    Each of the upper appliances is connected to an upper archwire  50  and each of the lower appliances is connected to a lower archwire  60 . In this example, both upper and lower archwires  50 , 60  have generally rectangular cross-sections in planes perpendicular to their longitudinal axes. An elastomeric O-ring ligature extends around each of the bracket tiewings to retain the respective archwire  50 , 60  in its archwire slot. Optionally, the distal ends of the archwires  50 , 60  are bent as shown in  FIG. 1  in a location adjacent the distal side of the respective buccal tube  32 , 42 . Alternatively, self-ligating appliances which use slidable doors, shutters, bales or clips may also be used. 
         [0037]    While not shown, some embodiments of the invention include a mirror image configuration of assembly  100  similarly installed on the left side of the upper and lower dental arches. Such a configuration allows a symmetrical application of forces on both sides of the dental arch. 
         [0038]    Orthodontic corrector  102  is part of the assembly  100  which couples the upper archwire  50  to the lower archwire  60 . Optionally and as shown here, the corrector  102  is coupled on one end to the upper archwire  50  between the upper bicuspid brackets  30  and the upper buccal tube  32 . As used herein, the “end” of a component, such as the corrector  102 , shall mean a portion of the component adjacent its outermost end, and shall not be limited, for example, to an outermost end wall of the component. On the opposite end, the corrector  102  is coupled to the lower archwire  60  between the lower cuspid and lower bicuspid brackets  40 . In the configuration shown, corrector  102  provides an expansion force bearing against the upper buccal tube  32  and the lower cuspid bracket  40 . This expansion force in turn generates a therapeutic force that can correct an overbite by urging the lower dental arch in the forward direction relative to the upper dental arch. 
         [0039]      FIG. 2  illustrates the corrector  102  detached from the archwires  50 , 60  and viewed from the opposite direction (from the lingual side). As shown, the corrector  102  includes a connector  104  for coupling to the upper archwire  50 . A cantilever  106  is coupled to the connector  104  at one end, and extends outwardly from the connector  104  in a generally distal direction. The opposite end of the cantilever  106  is coupled to a force module  108 . As shown, the force module  108  has two opposing ends, with one end coupled to the cantilever  106  and the opposite end adapted for coupling to the lower archwire  60 . 
         [0040]    Preferably, the force module  108  is similar in many respects to the bite corrector described in U.S. Pat. No. 5,964,588 (Cleary). As exemplified in  FIG. 2 , the force module  108  includes a first elongated tubular member  118 , a second elongated tubular member  120  that is received in the first member  118  in sliding, telescoping relation, and a third member  110  that is received in the second member. A helical compression spring  122  extends around the first tubular member  118  and has an outer end that bears against a distal end cap  124  fixed to the first member  118 . The opposite end of the spring  122  bears against an annular fitting  126  that is secured to an outer end section of the second member  120 . The third member  110  further includes an oversized stop  128  that engages the annular fitting  126  and limits the extent to which the third member  110  can be received into the second member  120 . 
         [0041]    The cantilever  106  is pivotally coupled to the force module  108  at attachment lug  125  which extends outwardly in a gingival direction from the distal end cap  124 . At the opposite end of the force module  108 , the outer mesial end of the third member  110  is formed into a loop-type configuration as shown in  FIG. 2  for extending around a section of the lower archwire  60 . Additional examples of loop-type configurations are set out in U.S. Pat. No. 6,669,474 (Vogt). Other constructions for connecting a force module to an orthodontic archwire are described in co-filed U.S. provisional patent application entitled “INTERARCH FORCE MODULE WITH LINK FOR ORTHODONTIC TREATMENT”, Ser. No. 61/168,946, filed on Apr. 13, 2009. In some embodiments, the outer end of the third member  110  also includes a line of weakness such as a recess or other area of reduced thickness for ease of bending the outer end section around the lower archwire  60 . Examples of suitable commercially-available force modules  108  are included in the FORSUS brand fatigue resistant Class II correctors from 3M Unitek Corporation (Monrovia, Calif.). 
         [0042]    When the connector  104  is connected to the archwires  50 , 60  in the manner described, the helical compression spring  122  urges the connector  104  and the third member  110  in directions away from each other. As a result, the connector  104  slides distally along the archwire  50  until it bears against the mesial side of the buccal tube  32 , while the third member  110  slides mesially along the archwire  60  until it bears against the distal side of the bracket  40 . Other aspects of operating the assembly  100  are similar to those of the appliance described in issued U.S. Pat. No. 6,558,160 (Schnaitter et al.). 
         [0043]    The connector  104  and cantilever  106  of the assembly  100  may be used with other types of force modules as well, and its use need not be limited to telescopic force modules such as the force module  108  shown. For example, the cantilever  106  may be coupled to a flat spring made from a shape-memory alloy such as disclosed in issued U.S. Pat. No. 5,752,823 (Vogt). Likewise, the cantilever  106  may be coupled to any other resilient elongated body that is bendable in an arc about references axes perpendicular to its longitudinal axis, such as the force modules described in U.S. Pat. No. 5,651,672 (Cleary). 
         [0044]      FIGS. 3-5  show the connector  104  as viewed from the lingual, distal, and occlusal directions, respectively. The connector  104  preferably shares some aspects with the connector component shown and described in copending U.S. provisional patent application entitled “ORTHODONTIC CONNECTOR PROVIDING CONTROLLED ENGAGEMENT WITH AN ORTHODONTIC WIRE”, Ser. No. 61/168,959, filed on Apr. 13, 2009. 
         [0045]    As shown in these figures, the connector  104  includes a body  130 . A pair of central posts  132 , a pair of mesial posts  136 , and a pair of distal posts  138  protrude outwardly from the body  130  towards a generally lingual direction. The central, mesial and distal posts  132 , 136 , 138  present aligned notches  144  which reside between each pair of posts  132 , 136 , 138 . A pair of elongated grooves  143  extend across the lingual side of the body  130  in directions transverse to the notches  144  and are located in the spaces between the central and mesial posts  132 , 136  and between the central and distal posts  132 , 138 . Optionally and as shown, the central, mesial and distal posts  132 , 136 , 138  are integral with the body  130 . 
         [0046]    A pair of resilient clips  150  are located in the grooves  143  and held captive by a retaining bar  142 , which is received in the aligned notches  144  and extends along generally mesial-distal directions. The notches  144  thereby provide mating surfaces that allow the retaining bar  142  to precisely register with the body  130  when joined. In an exemplary method of assembly, the clips  150  are first placed in the grooves  143  of the body  130 , the retaining bar  142  threaded through the clips  150 , and finally the retaining bar  142  welded, soldered, or adhesively attached to the mating surfaces of the notches  144 . The clips  150  have a mesial-distal width slightly smaller than the width of the grooves  143  to allow the clips  150  to flex freely. 
         [0047]    The central, mesial and distal posts  132 , 136 , 138  and the retaining bar  142  collectively present an elongated archwire slot  140 . As shown in  FIG. 3 , the archwire slot  140  extends in generally mesial-distal directions across the lingual side of the body  130  and is aligned with the pair of clips  150 . The archwire slot  140  further has a generally “U”-shaped configuration in sections transverse to its longitudinal axis. 
         [0048]    As seen from the distal direction in  FIG. 4 , each clip  150  has a generally “C”-shaped configuration and includes a pair of arm portions  152  that initially extend in lingual directions and then bend inwardly toward each other. Within each clip  150  is a wire-receiving region  154  aligned with the archwire slot  140 . The pair of clips  150  are disposed adjacent to the respective mesial and distal sides of the connector  104  and releasably retain the archwire  50  in the archwire slot  140  when the assembly  100  is installed as shown in  FIG. 1 . 
         [0049]    The clips  150  are shown in their normal, relaxed orientations in  FIGS. 2 ,  3 , and  4 . However, the arm portions  152  of each clip  150  are movable away from each other in order to admit the archwire  50  into a wire-receiving region  154  when so desired. The smooth, outer edge of the arm portions  152  enables each clip  150  to receive the archwire  50  by first pressing the archwire  50  against the outer curved edges of the arm portions  152 . As pressure is exerted by the archwire  50  on the curved edges, the arm portions  152  deflect away from each other in order to admit the archwire  50  into the wire-receiving region  154 . 
         [0050]    Once the archwire  50  is received in the wire-receiving region  154 , the inherent resiliency of each clip  150  enables arm portions  152  to spring back toward each other and toward their normal, relaxed configuration as shown in  FIGS. 2-4  to retain the archwire  50  in the archwire slot  140 . In preferred embodiments, the archwire  50  is a rectangular archwire and the archwire slot  140  includes a pair of rigid and opposing walls  141  (see  FIG. 3 ) that restrict relative rotation of the connector body  130  about the longitudinal axis of the archwire  50 . In some embodiments, the wire-receiving region  154  is somewhat larger than the cross-section of the wire in directions along both an occlusal-gingival reference axis as well as along a facial-lingual reference axis, thereby avoiding firm contact between each clip  150  and the archwire  50 . 
         [0051]    Also located on the body  130  is an elongated crimpable slot  160 , which extends across the body  130  in generally mesial-distal directions. As shown in  FIG. 4 , the crimpable slot  160  has a cross-section that is generally “U”-shaped when viewed in directions along the longitudinal axis of the crimpable slot  160 . Alternatively, other cross-sectional shapes could also be used. 
         [0052]    Optionally and as shown, the crimpable slot  160  has a slot bottom  162  that is non-parallel with the longitudinal axis of the archwire slot  140 . This aspect is particularly shown by  FIG. 5 , in which the slot bottom  162  (denoted by dashed lines) is slightly inclined toward the lingual direction from the mesial and distal edges to the mesial-distal center of the crimpable slot  160 . In this case, it is preferable that the mesial and distal taper of the slot bottom  162  is symmetrical about a reference plane that bisects the connector  104  into mesial and distal halves. This symmetry provides a manufacturing advantage, since it allows the same connector  104  to be used on either the left or right side of the dental arch. 
         [0053]      FIG. 6  shows in more detail the cantilever  106  and the manner in which it is coupled to the adjoining connector  104  and the force module  108 . In this exemplary embodiment, the cantilever  106  includes a single flexible wire  170  that is doubled back upon itself to form a closed loop  172  at the distal end of the cantilever  106 . The flexible wire  170  has a configuration such that the closed loop  172  is threaded through the attachment lug  125  of the force module  108  to form a pivotal coupling. 
         [0054]    Optionally and as shown in  FIG. 6 , the loop  172  is then secured using a collar  174 . The collar  174  engages the doubled flexible wire  170  in encircling relation at a position adjacent to the loop  172  and is crimped into place to prevent undue sliding along the flexible wire  170 . As an alternative, the collar  174  may also be welded, soldered, or adhesively fastened in place. 
         [0055]    As further shown in  FIG. 6 , the doubled flexible wire  170  is received into the crimpable slot  160  of the connector  104 .  FIG. 7  shows a cross-section of the crimp coupling between the flexible wire  170  and the crimpable slot  160  as viewed from the distal direction. Preferably, the flexible wire  170  is fully seated into the crimpable slot  160  and assumes a shape that conforms with the tapered slot bottom  162  as shown in  FIG. 6 . In preferred embodiments, the flexible wire  170  crimped to the connector  104  such that the cantilever  106  is rigidly coupled and does not slide or rotate relative to the connector  104  during the course of treatment. The slot bottom  162  aligns the flexible wire  170  in a slight acute angle relative to the archwire slot  140  of the connector  104 . As shown in  FIGS. 2 and 7 , the crimpable slot  160  is substantially closed when the cantilever  106  is secured to the connector  104 . 
         [0056]    As an alternative to crimp coupling the connector  104  and the cantilever  106 , the two components may be joined by welding, soldering, adhesive bonding, or some other type of mechanical connection. 
         [0057]    The cantilever  106  preferably comprises a flexible and resilient material that can withstand a significant amount of bending and twisting in response to forces transmitted from the force module  108  or even hard food objects during mastication. It is further preferable that the resilient material has sufficient memory to self-return the cantilever  106  to a certain, pre-determined orientation when relaxed (i.e. when external forces are removed). As shown here, the pre-determined orientation of the cantilever  106  is a generally straight orientation. Examples of suitable materials include, but are not limited to, shape-memory materials such as nickel-titanium alloys and the like. In exemplary embodiments, the cantilever  106  is made from a flexible wire  170  made from a nickel-titanium superelastic alloy and has a diameter of approximately 0.041 centimeters (0.016 inches). 
         [0058]    The flexibility and resilience of the cantilever  106  significantly improve the robustness of both the orthodontic corrector  102  and the orthodontic assembly  100  as a whole. For one, these aspects allow the cantilever  106  to provide a flexible connection between the archwire  50  and the force module  108 . Since the cantilever  106  resiliently deflects in a direction laterally of its longitudinal axis when external forces are encountered by the corrector  102 , the transfer of mastication forces to the archwire  50  and the connector  104  is reduced. Advantageously, forces transferred to bonded appliances such as the brackets  30 , 40  and the buccal tubes  32 , 42  are similarly reduced, leading to fewer bond failures between these appliances and the patient&#39;s teeth. 
         [0059]    Additionally, when the external forces are removed, the cantilever  106  springs back to its original orientation to ensure that the corrector  102  is once again properly aligned as depicted in  FIG. 1 . In this manner, the cantilever  106  flexibly maintains the distal end of the force module  108  in a location that is fixed relative to the connector  104  throughout the course of treatment. By maintaining proper and consistent alignment of the corrector  102  in the oral cavity, the likelihood of binding between couplings is also reduced, leading to fewer breakages between adjacent device components. 
         [0060]    As an added benefit, the cantilever  106  positions the coupling between the loop  172  and the attachment lug  125  of the force module  108  in a location that is distal to the buccal tube  32 . This provides a number of further advantages. First, positioning the coupling to the force module  108  distal, as opposed to mesial, to the buccal tube  32  provides a wider range of connection options between the corrector  102  and the lower dental arch. For example, this coupling creates sufficient space for the third member  110  to be alternatively coupled to the lower archwire  60  between the two lower bicuspid brackets  24  if desired by the orthodontist. This in turn can provide a Class II corrector with improved aesthetics since the third member  110  would be further hidden by the patient&#39;s cheeks. Even if this option is declined, positioning the coupling distal to the buccal tube  32  provides greater extension of the force module  108 , which in turn expands the range of jaw motion over which the compression spring  122  can be activated. 
         [0061]      FIGS. 8-11  are directed to an alternative embodiment of the invention using a cantilever with a somewhat larger cross-section. 
         [0062]      FIG. 8  shows an exploded view of an orthodontic corrector  202 . Similar to the corrector  102 , the corrector  202  has a connector  204  that includes a pair of resilient clips held captive within the connector  204  for reversably coupling to the upper archwire  50 . As indicated by  FIG. 8 , the connector  204  also includes a body  250  and a generally elliptical post  205  (shown using dashed lines) extending from the body  250  in a generally occlusal direction and terminating in an oversized occlusal end cap  207 . The post  205  extends through a complementally-shaped aperture in a cantilever  206  to couple the connector  204  to the cantilever  206  while rigidly coupling these components to each other. In some embodiments, the aperture in the cantilever  206  is slightly smaller than the cross-section of the post  205  so that there is a snug fit between the two components. 
         [0063]    The cantilever  206  is secured against the body  250  by occlusal end cap  207 . As shown by phantom lines in  FIG. 8 , the occlusal end cap  207  has an initially straight configuration. This straight configuration allows the cantilever  206  to be elastically stretched over the end cap  207  and onto the post  205  during assembly. The occlusal end cap  207  is subsequently bent at a right angle, as shown by the solid lines in  FIG. 8 . In this bent configuration, the end cap  207  extends along both occlusal and mesial edges of the cantilever  206  to prevent accidental disengagement. 
         [0064]    Preferably and as shown, the cantilever  206  extends away from the connector  204  in a generally distal direction. On the distal end of the cantilever  206  is a pivotal joint  211  between the cantilever  206  and the force module  108  (which is identical to the force module  108  described in connection with the embodiment shown in  FIGS. 1 and 2 ). As shown in  FIG. 10 , the distal end of the cantilever  206  includes a yoke  212 , which straddles the attachment lug  125  of the force module  108 . The yoke  212  includes a pair of aligned apertures  214 , which are aligned with a through hole in the attachment lug  125 . To assemble the pivotal joint  211 , a split rivet  216  is inserted through the apertures  214  and the through hole in the attachment lug  125  and fastened in place by bending over a pair of rivet flanges  218 . Optionally and as shown in  FIGS. 8 ,  10 , and  11 , the rivet  216  also extends through a washer  228 , which is interposed between the yoke  212  and the flanges  218 . Preferably, the rivet  216  is sized to allow relative pivotal movement between the cantilever  206  and the force module  108  about the longitudinal axis of the rivet  216 . Other aspects of the force module  108  have been already described and shall not be repeated here. 
         [0065]    In some embodiments, the cantilever  206  comprises a resilient polymeric material such as a modified urethane or polyolefin. In alternative embodiments, the cantilever  206  comprises a high modulus elastomer such a highly crosslinked rubber, ethylene-propylene-diene monomer (EPDM) rubber, copolyester elastomer or fluoroelastomer. If additional stiffness or strength is desired, hard organic or inorganic fillers may be blended into the polymeric material. Cantilever  206  is preferably capable of significant twisting and bending deflection. In some embodiments, the cantilever  206  comprises a material having a flexural modulus ranging from 30 to 100 megapascals (4351-14504 pounds per square inch). It is further preferred that the cantilever  206  is durable and does not plastically deform during the course of treatment. 
         [0066]    Other components of the assembly  100  and the correctors  102 , 202  may be manufactured according to any number of methods known to the skilled artisan. These methods include, but are not limited to, milling, investment casting, metal injection molding, and rapid prototyping. If desired, one or more of these parts can also be manufactured from other classes of materials, such as ceramics, polymers, or composites. If polymeric components are used, these may optionally be formed by milling, injection molding, extrusion or rapid prototyping. 
         [0067]    In preferred embodiments, the individual correctors  102 , 202  are manufactured and provided to the orthodontist as a complete set. For example, the manufacturer may pre-assemble the connector  104 , cantilever  106 , and the force module  108  (excluding the third member  110 ) to minimize installation time by the orthodontist. The correctors  102 , 202  may further be packaged with an assortment of third members  110  with a range of sizes to fit a variety of patients. 
         [0068]    In alternative embodiments, the cantilever  106 , 206  is connected directly to a bonded appliance such as an upper buccal tube or auxiliary wire segment. 
         [0069]    In further alternative embodiments, one or more of the orthodontic correctors above are adapted to correct a Class III malocclusion. Such correction may be achieved, for example, by connecting the one end of the assembly to the archwire  50  between the upper cuspid  12  and upper first bicuspid  14  and the other end of the assembly to the archwire  60  distal to the lower first buccal tube  42 . Similar configurations for treating Class III malocclusions are described in issued U.S. Pat. No. 6,558,160 (Schnaitter et al.). As before, the connections between components benefit from the increased robustness and functionality provided by the present invention. 
         [0070]    All of the patents and patent applications mentioned above are hereby expressly incorporated by reference. The embodiments described above are illustrative of the present invention and other constructions are also possible. Accordingly, the present invention should not be deemed limited to the embodiments described in detail above and shown in the accompanying drawings, but instead only by a fair scope of the claims that follow along with their equivalents.