Abstract:
According to one embodiment of the invention, a self-ligating orthodontic bracket apparatus has a body with an archwire slot, a lingual surface for mounting to a tooth and a guide track. The body and guide track form facing surfaces. A clip is engaged between the facing surfaces and is slideably movable in the guide track between an open position such that the archwire slot can receive an archwire and a closed position in which the clip can retain the archwire in the slot. The clip is dimensioned to extend the entire length and height of the slot in the bracket when in the closed position.

Description:
TECHNICAL FIELD 
     The field of this invention relates to a self-ligating orthodontic bracket. 
     BACKGROUND OF THE DISCLOSURE 
     Self-ligating orthodontic brackets are in common use for correcting irregularities of tooth position with relation to each other or in relation to the surrounding anatomy. While many different self-ligating orthodontic appliances have been devised and used, they all have drawbacks. They are either hard to install and adjust or are compromised in their ability to rotate and move teeth to the appropriate position. 
     What is needed is a self-ligating orthodontic bracket that is easy to install, and use and has a great capacity for rotating teeth and for performing all the functions necessary to move teeth into their proper position. 
     SUMMARY OF THE DISCLOSURE 
     According to one embodiment of the invention, a self-ligating orthodontic bracket apparatus has a body with an archwire slot, a lingual surface for mounting to a tooth and a guide track. The body and guide track form facing surfaces. A clip is engaged between the facing surfaces and is slideably movable in the guide track between an open position such that the archwire slot can receive an archwire and a closed position in which the clip can retain the archwire in the slot. The clip is dimensioned to extend the entire length and height of the slot in the bracket when in the closed position. 
     Preferably, a section of the clip has a tongue for movement between a first position and second position. The tongue extends into a notch in the body when in the first position and when the clip is in its closed position. The tongue abuts against the notch to retain the clip in the closed position. The facing surfaces are frictionally engaged with the clip when the tongue is in a second position and when the clip is in its open position. 
     Preferably, the tongue is mounted at a center section of the clip and has its first position being a normal bias position to extend into a notch in the body when the clip is in its closed position and to abut against the notch to bias and retain the clip in its closed position. The facing surfaces are frictionally engaged with the clip by resilient flexing of the tongue away from its normal bias position when the clip is in its open position. 
     In one embodiment, the body has cutaway outer sections extending from the guide track to the outer lateral edges of the body. The notch is located adjacent the slot and between the outer sections of the guide track. The tongue has a normal resilient bias extending lingually into the notch. 
     The center section has an access port that is positioned to be proximate to and extend beyond a gingival facing surface of the body when the clip is in the closed position. The gingival facing surface is accessible through the access port in the clip to allow a tool to extend through the access port and be leveraged against the gingival facing surface to exert a sliding force greater than the engagement force of the tongue in the notch. This provides flexing of the tongue outward to slide the clip from its closed position to its open position. 
     Preferably, the clip has a general T-shape with a crossbar section and the center section being a stem section of the T-shape. The crossbar section extends the length of the slot and the stem section contains the resilient tongue. Occlusal facing edges of the crossbar section engage the cutaway outer section of the body on both sides of the notch and the stein section engages the guide track when the clip is in the open and closed positions. An engagement slot in the body engages a gingival facing edge of the crossbar section when the clip is in the closed position. 
     Alternatively, the guide track may have a first and second guide track section generally facing outward toward each outer edge of the bracket. The clip may have two outer legs that engage the respective first and second guide track sections. 
     In accordance with another aspect of the invention, a body has a lingual surface for mounting to a tooth and an archwire slot. The body also has a guide track. The body and the guide track form facing surfaces; one of the facing surfaces has a notch therein. A clip is engaged between the facing surfaces and slideably movable in the guide track between an open position such that the archwire slot can receive an archwire and a closed position in which the clip can retain the archwire in the slot. A section of the clip has a tongue for movement between a first position and a second position often corresponding to an open position and closed position respectively of the clip. The resilient tongue extends into the notch in the body when in its first position, and when the clip is in its closed position. The tongue abuts against the notch to retain the clip in its closed position. The facing surfaces are frictionally engaged with the clip when the tongue is in its second position by resilient flexing when the clip is in its open position. 
     Preferably, the tongue is mounted at a center section of the clip and has its first position being a normal bias position to extend into a notch in the body when the clip is in its closed position and to abut against the notch to bias and retain the clip in its closed position. The facing surfaces are frictionally engaged with the clip by resilient flexing of the tongue away from its normal bias position when the clip is in its open position. 
     The center section has an access port that is positioned to be proximate to and extend beyond a gingival facing surface of the body when the clip is in the closed position. The gingival facing surface is accessible through the access port in the clip to allow a tool to extend through the access port and be leveraged against the gingival facing surface to exert a sliding force greater than the engagement force of the tongue in the notch. This provides flexing of the tongue outward to slide the clip from its closed position to its open position. 
     Preferably, the clip has a general T-shape with a crossbar section and center section being a stem section of the I-shape. The crossbar section extends the length of the slot and the stem section contains the resilient tongue. Occlusal facing edges of the crossbar section engage the cutaway outer section of the body on both sides of the notch. The stem section engages the guide track when the clip is in the open and closed positions. An engagement slot in the body engages a distal edge of the crossbar section when the clip is in the closed position. 
     In accordance with another aspect of the invention, a self-ligating orthodontic bracket apparatus has a body with an archwire slot and a lingual surface for mounting to a tooth. The body has a guide track. The body has a first beveled surface at one long side of the archwire slot beveled toward the guide track. The body has a second beveled surface at an opposing side of the archwire slot canted in the same general direction as the first beveled surface. A clip is engaged between the guide track and slideably movable between an open position such that the archwire slot can receive an archwire and a closed position in which the clip can retain the archwire in the slot. The clip is installable into the body by passing between the two beveled surfaces in front of the archwire slot to be received into the guide track. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Reference now is made to the accompanying drawings in which: 
         FIG. 1  is a perspective view of one embodiment of a self-ligtating orthodontic bracket according to the invention in the open position; 
         FIG. 2  is a similar perspective view illustrating the base member component shown in  FIG. 1 ; 
         FIG. 3  is a perspective view of the clip component shown in  FIG. 1 ; 
         FIG. 4  is a side elevational view of the clip shown in  FIG. 3 ; 
         FIG. 5  is a bottom plan view of the bracket shown in  FIG. 1 ; 
         FIG. 6  is a perspective view similar to  FIG. 1  showing the clip moved to the closed position; 
         FIG. 7  is a cross-sectional view taken along lines  7 - 7  shown in  FIG. 6  illustrating a lever tool in position to move the clip to the open position; 
         FIG. 8  is a cross-sectional view taken along lines  8 - 8  shown in  FIG. 1 ; and 
         FIG. 9  is a perspective and exploded view of an alternative embodiment in accordance with the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to  FIG. 1 , a self-ligating orthodontic bracket  10  has a body  12  and a clip  14 . The body  12  as shown in  FIG. 2  may be made from a metal material such as titanium. It has a contoured lingual surface  16  for adhering to a tooth member. The figures are oriented to show the bracket  10  as it would be basically viewed on a patient&#39;s upper teeth when the patient is sitting upright. When installed on lower teeth, the bracket  10  would be turned upside down from as shown in the drawings. A pair of gingival tie wings  18  and a pair of occlusal tie wings  20  extend from the body  12 . An archwire slot  22  extends laterally through the body  12  to hold an archwire  24  as shown in  FIG. 7 . 
     As more clearly shown in  FIGS. 2 and 5 , two slotted internal track sections  26  i.e. track slots  26  run vertically along the axially inner edge  28  of the pair of occlusal tie wings to slideably engage the clip  14 . As shown in  FIGS. 1 ,  2  and  6 , two laterally outer track sections, cutaway, or pocket sections  30  extend laterally outward from the track section  26  to the laterally outer sides  32  of the body  12 . Between the occusal tie wings  20  and the track sections  26  is a labial facing surface  34  of the body member  12 . A notch  36  is formed in the labial surface  34  that is adjacent the slot  22  and between the outer pocket sections  30 . The notch may have a leading canted surface  38 . The gingival edge of the tie wings  20  has an internal bevel  40  facing the outer pocket sections  30 . An engagement slot  42  lies on the other side of slot  22  and runs the entire width between the sides  32  of the body  12  and situated under the pair of gingival tie wings  18 . On the labial side of the engagement slot  42 , the body  12  has a bevel edge  44  canted into slot  22 . The internal bevel  40  and bevel edge  44  are canted in the same general direction. 
     The clip  14 , as shown in more detail in  FIGS. 3 and 4 , has a generally T-shape with a cross bar section  46  and a stem section  48 . The stem section has an access port  50  and a spring tongue member  52 . As shown most clearly in  FIG. 4 , the distal end  54  of tongue  52  bends out of the main plane of the clip  14 . Its normal position is at this bent position but the tongue can be resiliently flexed away from this normal bent position toward the main portion of the clip  14 . The tongue must have a width less than the width of the notch  36  and be positioned to sit in the notch  36  as described more fully later. The clip may be made from a spring quality stainless steel or a commercially available specialized metal for example, Elgiloy™. The metal may have memory set by heat treating. The clip may have a typical thickness of about 0.007 inches. Other thicknesses between 0.003 and 0.010 inches are foreseen. 
     The outer edges  56  of the stem section  48  engage the track slots  26  as best shown in  FIG. 5 . The crossbar section as best shown in  FIG. 1  engage the outer track section  30 . The track slots  26  and pocket section  30  has a thickness i.e. depth slightly greater than the thickness of the clip  14  to provide sliding movement. For example, the depth may be 0.010 inches to provide a 0.003 inch clearance. Other depths and clearances are foreseen depending on the application. However, when in the open position as shown in  FIG. 1  and in  FIG. 8 , the distal end  54  of tongue  52  resiliently engages the labial surface  34  of body  12  and the labial surface  60  of the clip  14  abuts against a lingual facing surface  59  of tie wings  20  to provide a friction to gently retain the clip  14  in position against free unintentional sliding but provide sliding motion when desired. 
     The archwire  24 , as shown in  FIG. 7 , is free to enter the open slot  22  when the clip is in the open position as shown in  FIGS. 1 and 8 . The clip  14  can then be moved by merely pushing the stem  14  to overcome the stopping friction caused by the tongue  52 . The clip  14  then can be moved to the closed position as shown in  FIGS. 6 and 7  thereby trapping the archwire  24  as shown in  FIG. 7 . The cross bar section  46  is moved up to cover the entire width of the slot  22  and the gingival edge engages the engagement slot  42 . The occlusal edges  58  of the cross bar section  46  maintain engagement in the outer pocket sections  30 . The outer edges  56  of stem section  48  still engage the track slots  26 . The distal end  54  of the tongue  52  is allowed to resiliently bias toward its normal position into notch  36  and engage the canted surface  38 . The tongue  52  thus provides a spring locking force when the clip  14  is in the closed position to prevent the clip  14  from unintentionally and undesirably slipping to the open position. 
     When the bracket  10  needs to be open, the access port  50  in clip  14  receives a lever tool  62  as shown in  FIG. 7 . The tip  64  of the lever tool engages the occlusal surface  66  of the body  12  and more particular a groove  68  shaped to align with the access port  50  when the clip  14  is in the closed position in body  12 . The lever  62  is merely pivoted downwardly with the tip  64  secured against the groove  68  and abutting against port  50  in the clip  14  to overcome the locking force of the tongue  52  in the notch  36 . The tongue  52  then flexes back toward the main plain of the clip and the clip  14  is then allowed to slide to the open position as shown in  FIGS. 1 and 8 . 
     The clip  14  is initially installed in the body by sliding the clip  14  against the bevel edge  44  and the clip  14  then enters the outer track section  30  via the bevel edges  40  on the other side of the slot  22 . The clip  12  material has enough flexure to slip into the track slot  26  and pocket section  30  while the top bar section  46  slips into slot  22  under bevel edge  44 . The clip may be installed before being heat-treated. Both the bracket body and the clip may be heat-treated at the same time. 
     Referring now to  FIG. 9 , an alternate embodiment of a bracket  110  is shown where the body  112  has its occlusal tie wings  120  having track slots  126  on the lateral outer edges  132 . The cutaway section or pocket section  130  adjacent the slot  122  extends laterally from the guide track toward the inner edges of the wings  120 . Two engagement slots  142  extend laterally across each gingival tie wing  118  with a gap in the middle. The clip  114  has a span section  146  and has two laterally outer legs  148  which engage the respective track slots  126  at the respective lateral outer edge  132  of the body  112 . The clip  114  has a center post section  147  with the access port  150  and two resilient tongue legs  152  each with a distal end  154 . The tongue ends  154  engage the ramp and notch section  136  between the track section  130  Functionally, the clip  114  and body  112  work in substantially the same fashion as the first embodiment. 
     In this fashion, the clip and body as described has several advantages. Firstly, it is easy to operate and does not require special tooling. It only requires a prong lever device that is a standard tool for orthodontists. The sliding motion between the open and closed positions is easy and requires no pivoting or flipping of clips or gates. Furthermore, the clip is secured in both the open and closed position against undesirable and unintentional movement. The effectiveness of the bracket is greater than standard brackets because the entire width of the bracket can be used to help create de-rotation of the teeth. Greater rotational forces can be created against the archwire in the desired direction to provide better de-rotation effects on the tooth when a larger lateral surface is used against the archwire. 
     Variations and modifications are possible without departing from the scope and spirit of the present invention as defined by the appended claims.