Abstract:
An orthodontic distalizing apparatus comprises at least one force generating element positioned intermediate a force dissipating element secured to the hard palate and/or alveolar ridge and a first tooth (e.g., a molar) that is being distalized. The at least one force generating element is positioned to apply a distalizing force on the molar in a direction substantially along a longitudinal axis of the dental arch and at a low level of the basal gingiva. The at least one force generating element may be configured to prevent inadvertent disassembly thereof during installation, adjustment and/or conversion of the apparatus between an active and a passive state. In addition, the at least one force generating element may be configured to be reversibly convertible between an active state and a passive state without requiring removal of the device from the patient&#39;s mouth. Moreover, the at least one force generating element may be configured to provide a continuous activation force of substantially constant magnitude during distalization of the molar. The apparatus may also be constructed so that the force dissipating element is connected to at least one anchoring tooth by a slidable coupling that absorbs all reaction forces transmitted substantially along a direction of the longitudinal arch. A second force dissipating element may be positioned intermediate the force dissipating element and a second tooth (e.g., a bicuspid) to facilitate the closing of any gaps that are created following distalization of the molar. A method of converting an orthodontic distalizing apparatus between an active and a passive state is also provided.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention relates to an orthodontic distalizing apparatus for correcting the relative position of the teeth.  
         BACKGROUND OF THE INVENTION  
         [0002]    Orthodontic distalizing devices for correcting the relative position of the teeth of a dental arch are known. In such known devices of this kind, spring-loadable pusher means are generally arranged on the side opposite the lingual side of the dental arch. Moreover, the pusher means are interposed between the means for anchoring the framework to a tooth selected for that purpose and the means for fastening to the further tooth being distalized of the same branch of the dental arch. The reaction force exerted by the pusher on the tooth being distalized is not discharged completely onto the basal gingiva and underlying bony support of the arch, but can also act at least partially on the tooth selected for anchoring of the framework, thus resulting in the risk of causing displacement of the latter as well.  
           [0003]    The pusher of the known distalizing apparatuses generally consists of a pusher pin which is fastened substantially tangentially to the tooth being distalized, and on which is mounted in coaxially sliding fashion a compression sleeve of a pusher spring. The spring is interposed between the head end of the pin, rigidly fastened to the means for fastening to the tooth being distalized, and the facing head end of the sliding sleeve. The latter is in turn joined to the anchoring means of the framework via wires or the like, with which it is held in the desired spring compression position. For this purpose the pusher pin must extend sufficiently beyond the anchoring tooth, in a direction opposite to the compression direction of the spring, as a result of which the pusher means have considerable dimensions and are thus retained non-rigidly or only in a direction opposite to the direction of spring compression on the anchoring tooth. The pusher pin therefore does not exert sufficiently precise directional guidance on the tooth to prevent the forces exerted by the pusher means from being expressed, even partially, as torques capable of causing tilting of the tooth from the correct vertical orientation and/or rotation thereof, and/or as components transverse to the longitudinal axis of the dental arch.  
           [0004]    A number of relatively simple and low-cost designs which overcome all the above-identified drawbacks of conventional distalizing apparatuses are disclosed in U.S. Pat. No. 5,785,520, issued Jul. 28, 1998, which is hereby incorporated by reference in its entirety. According to one embodiment disclosed in the &#39;520 patent, a distalizing apparatus  10  (illustrated in FIGS.  1 - 4  attached hereto) comprises a supporting framework  12  composed of an anatomical support element  14  (in the form of a Nance button) and a transverse structure  16  (in the form of a metal wire) embedded in Nance button  14 . Framework  12  is anchored to a pair of anchoring teeth  18  and  20  by attaching the two opposed ends of transverse wire  16  to bands  22  and  24 , respectively. Extending from Nance button  14  are two additional transverse structures  26  and  28  (also in the form of metal wires), both of which have ends joined by means of pusher elements  30  and  32  to bands  34  and  36 , respectively, for fastening to teeth  38  and  40  being distalized.  
           [0005]    In the illustrated embodiment, each pusher element  30 ,  32  generally comprises a pusher pin  42  and a narrow tube  44  that are telescopically engaged with one another (see FIG. 3), with an elastic element  46  (e.g., a compression spring as shown in FIGS. 1 and 2) captured therebetween. In addition, each pusher element includes a locking collar  48  that is slidably mounted on tube  44  so that compression spring  46  can be preloaded as desired by moving locking collar  48  towards or away from pusher pin  42  and locking it in position. Pusher elements  30  and  32  are assembled and installed in the dental arch with the proper position and orientation so that the forces generated thereby are exerted in the general direction of the longitudinal axis of the dental arch. During this installation process, the technician must take care when adjusting the position of locking collar  48  to ensure that pusher elements  30  and  32 —including their associated springs and locking collars—remain in the fully assembled state to prevent the possibility of one or more elements being swallowed or aspirated.  
           [0006]    As best seen in FIG. 2, the attachment points of pusher elements  30  and  32  to wires  26  and  28  are located as low as possible within the dental arch so that pusher elements  30  and  32  are within the basal zone of gingiva. Similarly, the attachment points of pusher elements  30  and  32  to bands  34  and  36 , respectively, are also provided as low as possible above (or in) the cervical zone so as to be as close as possible to the centers of resistance of teeth  38  and  40 . As recognized in the &#39;520 patent, this arrangement largely suppresses those components of the distalizing force exerted by pusher elements  30  and  32  which otherwise would act to tilt teeth  38  and  40  from their correct vertical orientations.  
           [0007]    To prevent pusher elements  30  and  32  from discharging any reactive forces on anchoring teeth  18  and  20 , transverse anchoring wire  16  may be provided with a pair of respective force compensation means  50  and  52  (in the form of wire loops). Wire loops  50  and  52  are suitably elastically preloaded by the technician in the direction opposite to the reaction force components resulting from pusher elements  30  and  32  applying their desirable distalizing forces. To ensure that no reaction forces are exerted on the anchoring teeth  18  and  20 , loops  50  and  52  must be carefully shaped to provide an offsetting bias force that is substantially the same magnitude but in the opposite direction as the anticipated reaction forces from pusher elements  30  and  32  acting against teeth  38  and  40  which are not absorbed by Nance button  14 .  
           [0008]    Another feature of distalizing apparatus  10  disclosed in the &#39;520 patent is that pusher elements  30  and  32  may be converted into a rigid (or inactive) state to prevent further application of distalizing forces. This makes it possible to use distalizing apparatus  10  as an anchoring structure or molar retainer once distalizing has been successfully completed and when it is necessary to move the anterior teeth toward the distalized teeth to close any space that has been created.  
           [0009]    According to the &#39;520 patent, this conversion may be accomplished by providing a slit (or notch)  54  in the end of tube  44  (see FIG. 3) so that it can be readily clamped to pusher pin  42  to prevent any relative sliding movement therebetween (see FIG. 4). The &#39;520 patent also mentions that this conversion process can be accomplished by applying a cold-setting or photo-activated resin to the junction of pin  42  and tube  44 . Although the distalizing appliance  10  of the &#39;520 patent when converted into a molar retainer by either of the foregoing methods can be reversed to restore pusher elements  30  and  32  to their active (or force-applying) states, the apparatus  10  must generally be removed from the patient&#39;s mouth in order to do so.  
           [0010]    In view of the forgoing, it is an object of the invention to implement an orthodontic distalizing apparatus which, like the devices disclosed in the &#39;520 patent, effectively eliminates all the above-noted drawbacks of conventional distalizing devices, while at the same time offering greater ease of installation, adjustment and conversion between the active and passive states.  
         SUMMARY OF THE INVENTION  
         [0011]    The invention achieves the aforesaid objects with an orthodontic distalizing apparatus comprising at least one force generating element positioned intermediate a force dissipating element secured to the hard palate and/or alveolar ridge and a first tooth (e.g., a molar) being distalized. The at least one force generating element is positioned to apply a distalizing force on the first tooth in a direction substantially along a longitudinal axis of the dental arch and a low level of the basal gingiva.  
           [0012]    According to a first aspect of an embodiment of the present invention, the at least one force generating element is configured to prevent inadvertent disassembly thereof during installation, adjustment and/or conversion of the apparatus between an active and a passive state.  
           [0013]    According to another aspect of an embodiment of the present invention, the at least one force generating element is reversibly convertible between the active and passive states while remaining installed in the patient&#39;s mouth.  
           [0014]    According to a different aspect of an embodiment of the present invention, the force dissipating element is connected to at least one anchoring tooth different from the first tooth by a slidable coupling that absorbs all forces transmitted along a direction of the longitudinal arch.  
           [0015]    According to a further aspect of an embodiment of the present invention, the at least one force generating element provides a continuous activation force of a substantially constant magnitude as the first tooth is distalized.  
           [0016]    According to a yet another aspect of an embodiment of the present invention, a second force generating element may be positioned intermediate the force dissipating element and a second tooth (e.g., a bicuspid) for closing any gap that is created by distalization of the first tooth.  
           [0017]    According to still another aspect of an embodiment of the present invention, a method for converting an orthodontic distalizing apparatus such as any of the foregoing between an active state and a passive state is also provided.  
           [0018]    These and other benefits and features of the invention will be apparent upon consideration of the following detailed description of preferred embodiments thereof, presented in connection with the following drawings in which like reference numerals are used to identify like elements throughout. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0019]    The particular characteristics of the invention and the advantages deriving from it will be evident in greater detail from the description of a preferred embodiment depicted as a non-limiting example in the attached drawings, in which:  
         [0020]    [0020]FIG. 1 shows a top view of a prior art apparatus applied to a dental arch.  
         [0021]    [0021]FIG. 2 shows a side elevation view of the prior art apparatus of FIG. 1.  
         [0022]    [0022]FIGS. 3 and 4 show an enlarged detail of the pusher elements of the prior art apparatus of FIG. 1 in two different operating states.  
         [0023]    [0023]FIG. 5 shows a first embodiment of an orthodontic distalizing apparatus in accordance with the present invention.  
         [0024]    [0024]FIG. 6 shows a second embodiment of an orthodontic distalizing apparatus in accordance with the present invention.  
         [0025]    [0025]FIG. 7 shows an enlarged sectional view of the locking collar associated with the apparatus of FIG. 6.  
         [0026]    [0026]FIG. 8 shows an enlarged sectional view of an alternative locking collar associated with the apparatus of FIG. 6.  
         [0027]    [0027]FIG. 9 shows a third embodiment of an orthodontic distalizing apparatus in accordance with the present invention.  
         [0028]    [0028]FIG. 10 shows a fourth embodiment of an orthodontic distalizing apparatus in accordance with the present invention.  
         [0029]    [0029]FIGS. 11 and 12 show a fifth embodiment of an orthodontic distalizing apparatus in accordance with the present invention.  
         [0030]    [0030]FIG. 13 shows a sixth embodiment of an orthodontic distalizing apparatus in accordance with the present invention.  
         [0031]    [0031]FIG. 14 shows an enlarged, exploded perspective view of a force generating element and an associated support linkage of the apparatus of FIG. 13.  
         [0032]    [0032]FIGS. 15 and 16 show a seventh embodiment of an orthodontic distalizing apparatus in accordance with the present invention.  
         [0033]    Before explaining at least one preferred embodiment of the invention in detail it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of the components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments or being practiced or carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein is for the purpose of description and should not be regarded as limiting. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0034]    Referring initially to FIG. 5, a first embodiment of an orthodontic distalizing apparatus  100  in accordance with the present invention is shown mounted to a maxillary jaw. As illustrated, apparatus  100  generally includes a pair of force generating elements  102  and  104 , a force dissipating element  106  (e.g., a Nance button) configured for engaging the hard palate and/or alveolar ridge, and a pair of anchoring elements  108  and  110 . Each force generating element is preferably positioned and oriented to apply a distalizing force to a respective molar  112 ,  114  in a direction substantially along a longitudinal axis of the dental arch and at a low level of the basal gingiva. As explained in the &#39;520 patent, applying forces at this low level and orientation causes the tooth distalizing forces to pass as close as possible to the center points of resistance of the molar  112 ,  114  being distalized, which minimizes risk of any undesirable tilting occurring during distalization.  
         [0035]    In the illustrated embodiment, each force generating element  102 ,  104  includes an elongated guiding element  116 ,  118 , respectively. Each guiding element  116 ,  118  includes a respective mesial end  120 ,  122  which is embedded in force dissipating element  106  and a respective distal end  124 ,  126  having an associated distal stop  128 ,  130  located thereon. As illustrated, each guiding element  116 ,  118  may be formed from a solid, heavy wire (e.g., large diameter stainless steel), and each distal stop  128 ,  130  may be formed on its associated wire by simply bending or kinking the distal end  124 ,  126  thereof. If desired, an annealing process may be used to facilitate the bending of distal ends  124  and  126  to form distal stops  128  and  130  and, if so, the distal ends  124  and  126  may be doubled back upon themselves to provide a smooth surface. As discussed below in connection with the additional exemplary embodiments, distal stops  128  and  130  could take other forms as are well known in the art.  
         [0036]    Preferably, each guiding element  116 ,  118  includes an additional bend or elbow  132 ,  134 , respectively, that is located in a substantially vertically spaced relationship with (i.e., generally above or below, depending on whether apparatus  100  is situated on the mandible or maxilla) the entry point of each guiding element  116 ,  118  into force dissipating element  106 . Thus, each guiding element  116 ,  118  may include a substantially horizontal main portion  136 ,  138  and a mesial portion  140 ,  142  having a substantially vertical component. As will be appreciated, the vertical component portions  140  and  142  of guiding elements  116  and  118  provide an improved geometry in that the reactive forces resulting from force generating elements  102  and  104  pushing against molars  112  and  114  are directed deeper into the palate than would be the case for a similar apparatus that is lacking such a vertical component. As a result of this structure, force dissipating element  106  is less likely to slip mesially (i.e., toward the front center of the mouth) than would otherwise be the case.  
         [0037]    As illustrated in FIG. 5, each force generating element  102 ,  104  further comprises an associated compression spring  144 ,  146  which is slidably mounted on the associated guiding element  116 ,  118  along with a pair of adjustable spring stops  148 ,  150  and  152 ,  154 , respectively, abutting against the anterior and posterior ends of each spring  144 ,  146 , respectively. In a preferred embodiment, each spring stop  148 ,  150 , and  152 ,  154  is releasably lockable in axial position along the horizontal portion  136  and  138 , respectively, of the associated guiding element  116  and  118 . In a particularly preferred embodiment, each spring stop  148 ,  150 ,  152  and  154  comprises a locking collar and a set screw  156  which allows the collar to be readily fixed in a position by rotating the screw in one direction or released and moved to a different position by rotating the screw in the opposite direction.  
         [0038]    Still referring to FIG. 5, each posterior spring stop  150 ,  154  is fixedly connected to the associated molar  112 ,  114  to move therewith by means of a support linkage  158 ,  160 . As illustrated, each support linkage  158 ,  160  may be formed of a relatively short and rigid lingual wire  159 ,  161  having one end attached (e.g., by means of soldering or welding) to the associated posterior spring stop  150 ,  154  and an opposite end attached (e.g., by means of a lingual tube and an associated band) to the associated molar  112 ,  114 . Persons skilled in the art will recognize that support linkages  158  and  160  could take other forms besides simple wires and could be secured to the posterior collars and/or to the molars by other means, e.g., directly attached to the molars using an adhesive compound. Regardless of the particular structure and attachment means used for support linkage  158 ,  160 , it can be seen that each force generating element  102 ,  104  is operatively positioned at a low level of the dental arch between force dissipating element  106  and the associated molar  112 ,  114  being distalized.  
         [0039]    If desirable for the particular application at hand, force dissipating element  106  may be further secured in place by means of anchoring elements  108  and  110 . As illustrated, each anchoring element  108 ,  110  includes an associated mesial end  162 ,  164  embedded in force dissipating element  106  and an associated distal end  166 ,  168  fixedly or releasably attached to an associated anchoring tooth (or teeth)  170 ,  172  (e.g., a bicuspid). In the particular embodiment illustrated in FIG. 5, distal end  166  of anchoring element  108  is secured to the crowns of two adjacent anchoring teeth  170  by use of an adhesive, while distal end  168  of anchoring element  110  is secured to anchoring tooth  172  by use of a soldered band  174 .  
         [0040]    In a preferred embodiment, each anchoring element  108 ,  110  may comprise a pair of wire segments  176 ,  178  and  180 ,  182 , respectively, with the wire segments of each pair being joined together by a force absorbing coupling  184 ,  186 , respectively. Each force absorbing coupling  184 ,  186  is designed to prevent transfer of substantially all the forces that are oriented in a direction substantially along the longitudinal direction of the arch, i.e., in a direction substantially parallel to the direction of distalization. Hence, any reaction forces that are imparted to force dissipating element  106  from the action of force generating elements  102  and  104  against molars  112  and  114  are not passed to anchoring teeth  170  and  172 . In the illustrated embodiment, each force absorbing coupling  184 ,  186  comprises a slidable connection formed by a tubular cylinder  188 ,  190  having an anterior end soldered to wire segment  176 ,  180 , respectively, and an opposite posterior end that slidably receives the other wire segment  178 ,  182 , respectively. Persons skilled in the art will recognize that the various elements of force absorbing couplings  184  and  186  could be reversed from that illustrated, i.e., the posterior ends of the tubular cylinders could be soldered to the wire segments.  
         [0041]    Now that the structure of distalizing apparatus  100  has been described in detail, a method of using apparatus  100  to distalize molars  112  and  114  will be provided. After mounting apparatus  100  in the maxillary or mandibular jaw, one or both of the force generating elements  102 ,  104  may be activated by moving the anterior spring stop(s)  148 ,  152  in a posterior direction (i.e., rearwardly or away from the front of the mouth) against the anterior end(s) of the associated compression spring(s)  144 ,  146  until the desired degree of compression has been achieved. Once this is done, the anterior spring stops(s)  148 ,  152  can be fixed in position (i.e., converted into a molar retainer) by turning the screw(s)  156  as appropriate to lock spring stop(s)  148 ,  152  in place. During this activation process, the technician need not be concerned with either of the force generating elements  102 ,  104  inadvertently coming apart because distal stop(s)  128 ,  130  prevent any such incident.  
         [0042]    After distalization has been successfully completed, apparatus  100  can readily be converted into a molar retainer by simply tightening the screw(s)  156  of all four spring stops  148 ,  150 ,  152  and  154 . Once this has been done, apparatus  100  will function as a Nance appliance anchored to molars  112  and  114 , which thus permits selected anterior teeth to be moved toward the recently distalized teeth  112 ,  114  to close any spaces created during distalization. If desired, the technician can remove one or both anchoring elements  108 ,  110  when apparatus  100  is being used as a molar retainer.  
         [0043]    Referring now to FIG. 6, a second embodiment of an orthodontic distalizing apparatus  200  is shown. For brevity, the description of distalizing apparatus  200  will be generally limited to its differences relative to distalizing apparatus  100  described above. For convenience, elements of distalizing apparatus  200  that are substantially similar to corresponding elements of distalizing apparatus  100  will be identified by the same reference numerals but preceded by a “2” instead of a “1”.  
         [0044]    Distalizing apparatus  200  differs from distalizing apparatus  100  described above in that each anterior spring stop  248 ,  252  comprises a generally cone-shaped collar  201  and a set screw  256 . As best seen in FIG. 7, cone shaped collar  201  comprises a cylindrical base portion  203  and a conical portion  205 . Conical portion  205  includes a threaded bore  207  which extends approximately perpendicular to the conical outer surface  217  and is thus at an angle relative to a central bore  209  that extends through collar  201  for slidably receiving one of the guiding elements  216 ,  218 . As a result of this structure, the anterior spring stops  248  and  252 —when slidably mounted on guiding element  216  and  218  with their respective conical portions  205  closest to the front of the mouth—are significantly easier to adjust in position because of the improved angle provided for accessing screws  256 . FIG. 8 shows an alternatively shaped collar  201 ′ which provides the same advantages as collar  201  but which requires less material for its manufacture. Collars  201  and  201 ′ can be made by casting and/or machining as well as several other manufacturing techniques that are well known in the art.  
         [0045]    Distalizing apparatus  200  also differs from distalizing apparatus  100  described above with respect to anchoring elements  208  and  210 . Unlike anchoring elements  108 ,  110  described above, each anchoring element  208 ,  210  provides a rigid (i.e., non-force absorbing) connection between force dissipating element  206  and anchoring teeth  270  and  272 . That is, anchoring elements  208  and  210  lack the slidable force absorbing coupling associated with anchoring elements  108  and  110  of apparatus  100  described above. Another difference is that the two anchoring elements  208  and  210  of apparatus  200  are secured to anchoring teeth  270  and  272 , respectively, by means of a pair of soldered bands  274  rather than a combination of soldered bands and an adhesive.  
         [0046]    Referring now to FIG. 9, a third embodiment of an orthodontic distalizing apparatus  300  is shown. For brevity, the description of distalizing apparatus  300  will be generally limited to its differences relative to distalizing apparatus  100  described above. For convenience, elements of distalizing apparatus  300  that are substantially similar to corresponding elements of distalizing apparatus  100  will be identified by the same reference numerals but preceded by a “3” instead of a “1”.  
         [0047]    Distalizing apparatus  300  differs from distalizing apparatus  100  described above in that force dissipating element  306  is in the form of an osseointegrated (e.g., subperiosteal or endosseous) implant  311 . Implant  311 , which resembles a button, is a relatively flat, disc-shaped fixture having a threaded aperture  313  for securing thereto the mesial ends  320 ,  322  of guiding elements  316 ,  318  or another transpalatal member. Implant  311  is known as an “indirect anchorage device,” which is a term of art given to implants that are placed solely for orthodontic purposes (e.g., for stabilizing specific dental units to which clinical forces are then applied) and are generally removed once their anchorage duties have been fulfilled. Implant  311  provides for reliable anchorage and dissipation of the reactive forces generated by force generating elements  302  and  304  with no possibility of any anterior or mesial movement and no requirement of patient compliance or dexterity. Presently, there are at least two indirect implants available in the United States: a device known as the OnPlant, and another called the Ortholmplant.  
         [0048]    Distalizing apparatus  300  also differs from distalizing apparatus  100  described above with respect to force generating element  302 . Unlike force generating element  102  of apparatus  100  described above, force generating element  302  is shown in its inactive (or passive) state in which the compression spring has been removed and both collars  348 ,  350  have been locked in position. Thus, element  302  will function as a molar retainer. It should be noted that FIG. 9 is intended purely for purposes of illustration and that in actual use the technician would typically convert both force generating elements  302  and  304  to the rigid (or passive) state. It should also be noted that the compression spring can usually be readily removed by simply grasping one end of the spring with a pliers and pulling with sufficient force to cause the spring to unwind from guiding element  316 .  
         [0049]    Referring now to FIG. 10, a fourth embodiment of an orthodontic distalizing apparatus  400  is shown. For brevity, the description of distalizing apparatus  400  will be generally limited to its differences relative to distalizing apparatuses  100  described above. For convenience, elements of distalizing apparatus  400  that are substantially similar to corresponding elements of distalizing apparatus  100  will be identified by the same reference numerals but preceded by a “4” instead of a “1”.  
         [0050]    Distalizing apparatus  400  differs from distalizing apparatus  100  described above in that force generating element  404  has been modified to provide continuous force activation. More specifically, force generating element  404  has been modified relative to force generating element  104  of apparatus  100  in that anterior spring stop  452  is free floating (i.e., rather than fixed in one position) during distalization and that element  404  additionally includes an elastic strap (or chain)  415 . As illustrated, elastic strap  415  is stretched (or tensioned) between the medial face of anterior spring stop  452  and the distal end  426  of guiding element  418 . Although strap  415  is illustrated with its anterior-most loop  417  extending around wire  418 , loop  417  could instead be secured directly to collar  452 . One way this could be accomplished would be to substitute for collar  452  a collar similar to locking collar  652 A (see FIGS. 13 and 14) which provides a convenient tie off  655  (as described in detail below).  
         [0051]    Returning now to FIG. 10, elastic strap  415  applies a force in a posterior direction to anterior spring stop  452  that directly opposes the force applied in an anterior direction to anterior spring stop  452  by compression spring  446 . With these two opposing forces in equilibrium, elastic strap  415  will compress anterior spring stop  452  in a posterior direction against compression spring  446  to drive posterior spring stop  454  distally to cause spring  446  to remain continuously in a (nearly) fully compressed state. That is, so long as elastic strap  415  retains its memory, force generating element  404  will continue to provide its full distalizing force regardless of how far molar  414  moves in a posterior direction during distalization. Once again, it should be noted that FIG. 10 is intended solely for purposes of illustration and that apparatus  400  when used in actual practice by a technician would be modified to include the elastic strap  415  on both of the force generating elements  402  and  404 .  
         [0052]    Referring now to FIGS. 11 and 12, a fifth embodiment of an orthodontic distalizing apparatus  500  is shown. For brevity, the description of distalizing apparatus  500  will be generally limited to its differences relative to distalizing apparatus  100  described above. For convenience, elements of distalizing apparatus  500  that are substantially similar to corresponding elements of distalizing apparatus  100  will be identified by the same reference numerals but preceded by a “5” instead of a  
         [0053]    Distalizing apparatus  500  differs from apparatus  100  in that in place of anchoring element  108  in apparatus  100 , apparatus  500  includes a force generating element  502 ′. Although not illustrated, apparatus  500  also includes a similar force generating element on the opposite side of the dental arch in place of anchoring element  110  in apparatus  100 . Thus apparatus  500  includes a first pair of force generating elements  502  positioned between force dissipating element  506  and molars  512 , and a second pair of force generating elements  502 ′ positioned between force dissipating element  506  and bicuspid  570 . Each force generating element  502 ,  502 ′ includes an associated spring  544 ,  544 ′ captured between an anterior spring stop  548 ,  548 ′ and a posterior spring stop  550 ,  550 ′. In addition, each force generating element  502 ,  502 ′ includes an associated distal stop  528 ,  528 ′. In the illustrated embodiment, distal stop  528  is formed as a double-back and distal stop  528 ′ is formed by a solder ball.  
         [0054]    With the foregoing arrangement, apparatus  500  can be utilized in a two step method to first distalize molars  512  and, subsequently, to close any gaps that are created. In the first step, spring stops  548 ,  548 ′ and  550 ′ are moved to their desired positions and then fixed in place, while posterior spring stop  550  of thrust generating element  502  is allowed to freely slide along guiding element  516 . Because spring stops  548 ′ and  550 ′ of force generating element  502 ′ are both fixed in position, force generating element  502 ′ will function as an anchoring element (or retainer) during this first step. By contrast, because spring stop  550  of force generating element  502  is not fixed in position, the biasing force provided by compression spring  544  will cause molar  512  to distalize and thus create a space (or gap)  519  between molar  512  and bicuspid  570  (see FIG. 12). According to a second step, space  519  can be closed (or reduced) by distalizing bicuspid  570  toward molar  512 . This may be accomplished using apparatus  500  by fixing the position of posterior spring stop  550  of thrust generating element  502  while also unlocking posterior spring stop  550 ′ of thrust generating element  502 ′ so that it is free to slide along elongated guiding element  516 ′. Thus, the biasing force provided by compression spring  544 ′ will cause bicuspid  570  to distalize toward molar  512 , while at the same time thrust generating element  502  will function as an anchoring element. After bicuspid  570  has been sufficiently distalized to close (or reduce) space  519 , posterior spring stop  550 ′ of thrust generating element  502 ′ can again be fixed in position to place apparatus  500  in its inactive state.  
         [0055]    Apparatus  500  also differs from apparatus  100  in the attachment of support linkage  558  to molar  512 . In particular, support linkage  558  includes a short and rigid lingual wire  559  that has one of its ends attached to molar  512  by means of a lingual sheath  521  oriented generally transverse to the longitudinal axis of elongated guiding element  516 . As such, support linkage  558  can easily be decoupled from molar  512  by simply grasping wire  559  with a pliers and pulling downward with sufficient force to remove the end of wire  559  from lingual sheath  521 . This facilitates adjustment of apparatus  500  and/or replacement of one or more of its elements after it has been installed in the patient. If desired, the end of wire  559  may have a square cross-section to facilitate its connection to lingual sheath  521 . A similar releasable coupling arrangement may be provided between collar  548 ′ and bicuspid  570 .  
         [0056]    Referring now to FIGS. 13 and 14, a sixth embodiment of an orthodontic distalizing apparatus  600  is shown. For brevity, the description of distalizing apparatus  600  will be generally limited to its differences relative to distalizing apparatus  100  described above. For convenience, elements of distalizing apparatus  600  that are substantially similar to corresponding elements of distalizing apparatus  100  will be identified by the same reference numerals but preceded by a “6” instead of a “1”.  
         [0057]    Distalizing apparatus  600  differs from apparatus  100  in that in place of the solid, fixed length guiding element  116  and the short, rigid lingual wire  159  of apparatus  100 , apparatus  600  includes a multi-piece, expandable length guiding element  616  and an elongated, coiled support linkage  659 , respectively. In addition, apparatus  600  includes alternative locking collars  648  and  650  which, as described more fully below, include a number of features not present in collars  148  and  150  of apparatus  100 .  
         [0058]    According to the illustrated embodiment, elongated guiding element  61   6  comprises a mesial portion  640  formed by a solid, heavy gauge (i.e., large diameter) wire, a substantially horizontal main portion  636  formed by a hollow tube, a distal end  624  configured to be slidably received within the interior of hollow tube  636 , and a distal stop  628  formed on distal end  624  by a double (asymmetric) nail-head end. Solid rod  640  may have its posterior end slidably received within the anterior end of hollow tube  636 , and the two ends may be coupled together by laser welding  629 .  
         [0059]    In an exemplary embodiment, each locking collar  648 ,  650  includes a cylindrical base portion  649 ,  651 , respectively, and a transversely extending screw receiving portion  653 ,  655 , respectively. As best illustrated in FIG. 14, each screw receiving portion  653 ,  655  may include a funnel-shaped opening  657 ,  659  that leads to a threaded bore  607  for facilitating the reception of a set screw  656  therein. As best illustrated by FIG. 13, each screw receiving portion  653 ,  655  has an exterior cylindrical surface that provides a convenient tie off location for a ligature wire, elastic strap, or any other orthodontic element without requiring a permanent connection. For example, coiled support linkage wire  659  is illustrated with a mesial portion  661  tied off to screw receiving portion  655  of collar  650 . Because support linkage wire  659  is tied to collar  650  rather than permanently fastened (e.g., welded) thereto, wire  659  can be easily decoupled from collar  650  to facilitate adjustment thereof. As illustrated, support linkage wire  659  also includes a central coiled portion  663  extending around (and thus coupled to) distal stop  628  of movable distal end  624 , as well as a distal end  665  that is releasably secured to molar  612  by a lingual sheath and a band. Central portion  663  may also include one or more loops extending around the elongated cylindrical base portion  651  of locking collar  650 .  
         [0060]    With the foregoing structure, persons skilled in the art will recognize that guiding element  616  has an adjustable length. In particular, the length of guiding element  616  will vary in accordance with the amount or distance that molar  612  is distalized. More specifically, when collar  648  is locked and collar  650  is unlocked, compression spring  644  will cause collar  655  to move in a posterior direction along the exterior of hollow tube  636 . As collar  650  continues to move in a posterior direction, it will eventually extend beyond the posterior end of hollow tube  636  and abut against the anterior-most flange or head on distal stop  628 . Once this occurs, any additional posterior movement of collar  650  resulting from further expansion of compression spring  644  will cause distal end  624  to withdraw out of the interior of hollow tube  636  and thus effectively lengthen guiding element  616 . Thus, apparatus  600  is advantageous in applications where space is at a premium because the length of guiding element  616  will be only as long as necessary to accomplish the distalization. Hence, apparatus  600  is less likely to interfere with swallowing or cause any other discomfort to the patient.  
         [0061]    Persons skilled in the art will also recognize that the coiled shaped of support linkage  658  provides several advantages over a relatively short, straight wire. For example, the coiled shape of lingual wire  659  increases the length of support linkage  658  which provides it with a longer lever action when it is desirable to torque or rotate molar  612 . As another example, the coiled shape of lingual wire  659  allows the technician to increase the effective distalization range of apparatus  600  by uncoiling wire  659  as desired.  
         [0062]    Referring now to FIGS. 15 and 16, a seventh embodiment of an orthodontic distalizing apparatus  700  is shown. For brevity, the description of distalizing apparatus  700  will be generally limited to its differences relative to distalizing apparatus  600  described above. For convenience, elements of distalizing apparatus  700  that are substantially similar to corresponding elements of distalizing apparatus  600  will be identified by the same reference numerals but preceded by a “7” instead of a “6”.  
         [0063]    Distalizing apparatus  700  differs from apparatus  600  in that force generating element  702  includes an anterior locking collar  748  that is elongated and a posterior collar (or spring stop)  750  that is non-lockable. According to an exemplary embodiment, anterior locking collar  748  includes a cylindrical base portion  749  having a mesio-distal length of about 7 mm when measured from the center of a central threaded bore  707  to a posterior edge  765 . In addition, posterior spring stop  750  has a mesio-distal length of about 0.5 mm. As persons skilled in the art will recognize, the first and second bicuspids  770  of adult humans measure on average about 7.2 mm and 6.8 mm, respectively, taken along a mesio-distal line through the crowns. See Black, O. V., “Descriptive Anatomy of the Human Teeth,” ed. 4, Philadelphia, Pa.,  1897 , The S.S. White Dental Manufacturing Co. Quite commonly, a molar  712  needs to be distalized because it has encroached in the anterior bicuspid space (i.e., moved forwardly into the arch). Thus, it will be appreciated by persons skilled in the art that anterior locking collar  748  has a length substantially equal to the maximum mesio-distal length of a space (or gap)  719  that is likely to be created during distalization. With the forgoing construction, it is possible to quickly convert force generating element  702  into a rigid, mechanically fixed retainer after distalization is complete by removing spring  744  and sliding anterior locking collar  748  in a posterior direction until it abuts posterior collar  750 , and then locking anterior  748  collar in place.  
         [0064]    It is important to note that the above-described preferred embodiments of the distalizing apparatuses are illustrative only. Although the invention has been described in conjunction with specific embodiments thereof, those skilled in the art will appreciate that numerous modifications are possible without materially departing from the novel teachings and advantages of the subject matter described herein. For example, although each distalizing apparatus disclosed and illustrated above includes a pair of force generating elements, only one force generating element need be used if the molar(s) requiring distalization are all on the same side of the dental arch. In addition, although the apparatuses are all shown being anchored to bicuspids, other teeth including incisor, canines or other molars could be used as an anchoring teeth if desired. Accordingly, these and all other such modifications are intended to be included within the scope of the present invention. Other substitutions, modifications, changes and omissions may be made in the design, operating conditions and arrangement of the preferred and other exemplary embodiments without departing from the spirit of the present invention.