Patent Publication Number: US-2021177550-A1

Title: Self-ligating bracket for orthodontics

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to German patent application 10 2019 134 575.8 filed on Dec. 16, 2019, the content of which is fully incorporated herein by this reference. 
     DESCRIPTION 
     Field of the Invention 
     The invention proceeds from a self-ligating bracket for orthodontics comprising a socket, an occlusal wall that extends from the socket, a gingival wall that extends from the socket, a groove, which separates the occlusal wall and the gingival wall from each other, and extends continuously in the mesial to distal direction, a fastening side facing away from the groove for adhesively bonding the bracket to a lingual or vestibular surface of a tooth, a slit, which extends in the gingival to occlusal direction, and is bordered by a lingually situated surface and by a labially situated surface, and a resilient clamp, which has a first clamp leg and a second clamp leg that are connected with each other by an occlusally or gingivally arranged clamp bend. The the first clamp leg is inserted in the slit between the lingually situated surface and the labially situated surface, and can be moved therein in a gingival-occlusal direction between a closed position and an open position of the clamp, wherein the first clamp leg is set up in such a way as to prevent an unintended loss of the clamp. 
     BACKGROUND OF THE INVENTION 
     For example, such brackets are known from DE 10 2004 056 168 B4 and DE 10 2005 056 184 B4. In these brackets, a tongue directed against the occlusal wall is cut out of a labial clamp leg, and bent in a labial direction so as to include an acute angle with the lingual clamp leg. The labial surface bordering the slit is further removed or interrupted in the area of the gingival wall and in the area of the groove, so that the tongue can be pressed down by introducing a tool into the groove from a labial direction. The tongue directed against the occlusal wall prevents the clamp from inadvertently sliding out of the slit in its open position and being lost. Brackets in which the clamp leg moveable in the slit is set up in such a way as to prevent the clamp from slipping out of the slit in its open position have proven themselves in practice time and again. Manufacturing a clamp with such a bent tongue is difficult, and can be associated with relatively high production tolerances, because the materials with a good resilience that are well suited for achieving a high elasticity for the chamber are usually hard to plastically deform. 
     US 2010/0062387 A1 discloses a bracket of a different type, which has a lifting element between the labial surface of the bracket and the labial leg of the clamp. The lifting element can be turned, so as to labially lift the labial clamp leg in the closed position of the clamp, and thereby limit the forces that the clamp exerts on the archwire. To this end, the lifting element can be provided with a thread or a cam disk mechanism. The lifting element has a cylindrical head, which has a slit, and sits in an oblong hole of the labial clamp leg, so as to allow the lifting element to be set from outside. At the same time, the length of the oblong hole in the labial clamp leg limits the displacement path of the clamp between its closed position and open position. Contaminants and food particles can very easily get stuck in the oblong hole and the lifting element, and even become compacted by the chewing process. Such food particles are practically impossible to remove with the usual toothbrushing methods. This can block a displacement of the clamp in its open position. 
     US 2009/0325120 A1 discloses a bracket of yet another different type. This bracket is a purely passive bracket without a clamp, but has a slider displaceable on a dovetail guide in the gingival-occlusal direction, which extends up to the gingival wall in its closed position, and exposes the groove in its open position. The socket has an integral ramp-shaped projection, which interacts with latching contours on the slider, and limits its displacement in the occlusal direction in its open position. The ramp-shaped projection and/or the latching contours of the slider are flexible enough to ensure a latching effect in the open position and closed position. As a consequence, such a bracket cannot be fabricated out of inflexible materials, such as ceramics. 
     SUMMARY OF THE INVENTION 
     An object of the present invention for a bracket of the kind mentioned at the outset is to improve and simplify clamp manufacture. 
     This object is achieved by a bracket with the features indicated in claim  1 . Advantageous refinements of the invention are the subject of dependent claims. 
     The self-ligating bracket for orthodontics according to the invention has a socket, an occlusal wall that proceeds from the socket, a gingival wall that proceeds from the socket, and a groove, which separates the occlusal wall and the gingival wall from each other, and extends continuously in the mesial to distal direction. The side of the bracket facing away from the groove is referred to as the fastening side, which is designed to be adhesively bonded to a tooth. The fastening side of the bracket according to the invention can be adhesively bonded to a lingual or a vestibular surface of the tooth. The groove is also referred to as “slot”. It is used to receive an archwire, which usually leads through a sequence of brackets that are fastened to a row of teeth lying one next to the other. Pulling and/or twisting can generate a prestress in the wire, which is conveyed by the archwire to the brackets, and from the latter to one or several teeth, so as to change their position. 
     The bracket has a slit, which extends in the gingival to occlusal direction, and is bordered by a lingually situated guiding surface and by a labially situated guiding surface. The bracket further has a resilient clamp, which has a first clamp leg and a second clamp leg that are connected with each other by a bent section. This bent section is referred to as a clamp bend, and can be arranged occlusally or gingivally, depending on the orientation in which the bracket is adhesively bonded to the surface of the tooth. In a bracket whose fastening side is intended to be adhesively bonded onto a vestibular surface of a tooth, the first clamp leg is also referred to as a lingual leg, and the second clamp leg as a labial leg. The first clamp leg has a longitudinal direction that runs in the gingival-occlusal direction, and also extends in a plane. The first clamp leg is inserted in the slit between the lingually situated surface and the labially situated surface, and can be moved therein in a gingival-occlusal direction between a closed position and an open position of the clamp. When the clamp is moved from gingival to occlusal for opening purposes, the clamp bend is occlusally arranged. In the closed position of the clamp, the second clamp leg then extends until into a cutout in the gingival wall. In the open position of the clamp, the tip of the second clamp leg rests on the occlusal wall, so that an archwire can be inserted into the groove or removed from the groove. In the closed position, the second clamp leg closes the groove and resiliently abuts against the archwire, so as to press it against the base of the groove. Therefore, such a bracket is referred to as an “active bracket”. In a case where the archwire exerts a force on the second clamp leg that exceeds the restoring force of the clamp, the recess in the gingival wall can be bordered by a stop, which the second clamp leg hits when the archwire acts on the second clamp leg with a high enough force. The stop thus limits the distance of the second clamp leg from the base of the groove. The stop in the gingival wall further limits the largest possible size of the archwire in the lingual-labial direction. It can alternatively also be provided that the clamp be displaced from occlusal to gingival for opening purposes. In such a case, the clamp bend is gingivally arranged, and the second clamp leg extends until into a cutout of the occlusal wall in the closed position, while its tip rests on the gingival wall in the open position. 
     Given an occlusally arranged clamp bend, the clamp can be held in its closed position because the second clamp leg is sprung against the occlusal wall in the closed position, and can only be moved out of the closed position into the open position by being elastically bent up. Given a gingivally arranged clamp bend, the second clamp leg is sprung against the gingival wall. 
     The first clamp leg of the bracket according to the invention is set up in such a way as to prevent an unintended loss of the clamp during interaction with other parts of the bracket. The first clamp leg has at least one oblong recess, into which protrudes a projection that proceeds from the lingually or labially situated surface of the slit. The recess in the first clamp leg extends in the gingival-occlusal direction, and is bordered on its end facing away from the clamp bend by a stop, which hits the projection in the open position of the clamp and limits a further movement of the clamp. As a result, the clamp cannot be occlusally or gingivally moved beyond its open position in the direction of the clamp bend. There is a limit on how much the first clamp leg can be pushed out of the slit, so that the clamp cannot fall out of the slit. 
     The surface situated opposite the projection forms an escape space inside of the slit, into which the first clamp leg escapes with the stop under a resilient deformation when the stop slides over the projection during insertion of the clamp into the slit. The surface lying opposite the projection is here formed in such a way as to yield an escape space, in particular in the region lying opposite the projection. For example, the escape space can take the form of a cavity, recess, depression, pocket, or channel. If the projection proceeds from the labially situated surface of the slit, it protrudes in the lingual direction into the recess of the first clamp leg. If the first clamp leg reaches the projection during insertion, the clamp leg is resiliently deformed in a lingual direction, and escapes into the escape space, which is formed in the lingually situated surface of the slit. By escaping in this way, the stop glides over the projection without the projection deforming. The projection can be inflexible. In the escaping process, the first clamp leg is bent around a line that runs along its plane of extension. 
     The invention has significant advantages:
     The first clamp leg in conjunction with the projection present inside of the slit reliably prevents an unintended loss of the clamp when it is transferred from the closed position into the open position. The first clamp leg is prevented from unintendedly slipping out of the slit.   Clamp manufacture is substantially simplified. The clamp no longer needs to be plastically deformed to prevent it from slipping out.   The oblong recess in the first clamp leg can be manufactured very easily by punching, for example an oblong hole or an edge area of the leg.   As a result, the clamp can be manufactured with a much greater precision and less manufacturing tolerances.   Apart from the resilient clamp, the bracket can be manufactured out of an inflexible material, which is practically impossible to resiliently deform, for example ceramics. Only the clamp is elastically deformed when inserting the first clamp leg into the slit.   The projection and the escape space arranged opposite it can be easily formed within this slit, in particular if the bracket is molded in one piece, in particular via metal injection molding (MIM) or sintering out of ceramic.   

     In a further embodiment of the invention, the surface of the slit lying opposite the projection may contain at least one flat guiding surface for the first clamp leg. The surface that borders the slit, and from which the projection extends, may contain a flat guiding surface for the first clamp leg, in particular be designed as a flat guiding surface. The surface from which the projection extends may be completely flat. The guiding surfaces in the lingually situated surface and in the labially situated surface of the slit may run parallel to each other. This can ensure a good guidance of the first clamp leg. 
     The side of the projection within the slit facing the clamp bend may run inclined to the guiding surface from which the projection proceeds, in particular at an angle of 15° to 25°. This makes it easier for the stop to slide over the projection while inserting the first clamp leg into the slit, and escape during resilient deformation. The side of the projection facing away from the clamp bend may be inclined more strongly toward the guiding surface than its side facing the clamp bend. This causes the first clamp leg to latch in, and provides a good safeguard against undesired loss. 
     In another embodiment, the fastening side of the bracket may have a widened base, whose width as measured in a mesial to distal and/or gingival to occlusal direction is greater than the corresponding width of the socket. Such a widened base is also referred to as a “pad”, and can enlarge the area on the fastening side available for adhesively bonding the bracket, thereby improving the adhesion of the bracket to the tooth. The fastening side may also be provided with structures, for example undercut projections in an alternating orientation, which result in a distinctly better adhesion of the backet to the tooth while adhesively bonding the bracket with a tooth. In brackets made out of metal, the base may also be manufactured separately, and only connected with the socket of the bracket after the fact via welding. The occlusal wall may have a ligature wing or even several ligature wings. The gingival wall may have at least one gingival ligature wing. Ligature wires can be secured to ligature wings in a manner known in the art. 
     The slit in which the first clamp leg is inserted may run transverse to the groove, in particular perpendicularly to the groove. In particular, the slit may extend continuously through the socket. As an alternative, the slit may be closed on the side of the bracket facing away from the clamp bend, wherein in particular the gingival side of the bracket may here be involved. The slit may run in the socket between the groove and the fastening side of the bracket. In particular, the base of the groove may run continuously without interruption from mesial to distal. Then there exists no passage between the slit and the groove. This can make it easier to manufacture the bracket, in particular a one-piece bracket. The bracket has less free spaces inside, which can become clogged with deposits. 
     The surface bordering the slit on the side of the first clamp leg facing away from the groove may protrude over the free end of the first clamp leg in each position of the clamp. The “free end” is understood as the end of the clamp leg facing away from the clamp bend. A positioning aid for a tool may be provided at the free end and/or before the free end of the first clamp leg, with which the clamp can be moved from the closed position into the open position by pressing against the free end of its first clamp leg. Such a positioning aid does not weaken the clamp and its restoring force. Moreover, the first clamp leg cannot escape when pressure is exerted on its free end, because it is guided along a straight line in the slit in which it is inserted. A channel extending from gingival to occlusal may be provided in the socket as the positioning aid, which ends at a stop that is covered by an end of the first clamp leg when the clamp is in its closed position. However, alternatively or additionally the second clamp leg may have a hole into which a pin-shaped tool can engage in order to move the clamp out of its closed position into its open position. 
     In a first variant of the bracket according to the invention the first clamp leg may have a central recess. In particular, the latter may be designed as an oblong hole that extends in the longitudinal direction of the first clamp leg. The end of the oblong hole facing away from the clamp bend may comprise the stop for the projection proceeding from the socket. An oblong hole in the first clamp leg can be manufactured very easily. The escape space may be provided by a channel in the surface of the slit situated opposite the projection. The channel extends from gingival to occlusal, in particular over the entire length of the slit. The channel may be arranged between two flat guiding surfaces for the first clamp leg. The surface of the slit lying opposite the projection thus contains two guiding surfaces, which extend along the mesial or distal edge of the first clamp leg. As a result, very good guidance can be ensured for the first clamp leg in the slit. If it is intended that such a bracket be fastened on a vestibular surface of a tooth, in particular the lingually situated surface of the slit can contain the channel and the two guiding surfaces, which extend mesially and distally next to the channel along the edges of the first clamp leg. 
     In a second variant of a bracket according to the invention, the first clamp leg may each have a recess on its mesial edge and on its distal edge. Each of the recesses is bordered by a stop at its end facing away from the clamp bend. A projection proceeding from the lingually or labially situated surface of the slit protrudes into each of the recesses. An escape space is formed in the slit opposite each projection. Each escape space may be provided by a respective channel in the surface of the slit lying opposite the projection. The channels may extend from gingival to occlusal, in particular over the entire length of the slit. The flat guiding surface in the surface of the slit lying opposite the projection may be arranged between the two channels. 
     In the first and second variants of the bracket according to the invention, the line around which the first clamp leg is bent while yielding to the projection during insertion of the clamp into the slit under a resilient deformation is a line that runs along the longitudinal direction of the first clamp leg. 
     In a third variant of the bracket according to the invention, the escape space may be comprised of a pocket in the surface of the slit that is opposite the projection. The pocket extends from gingival to occlusal, in particular over the entire width of the first clamp leg and/or the slit. The line around which the first clamp leg is bent as it yields to the projection during insertion of the clamp into the slit under a resilient deformation is here a line, which runs transverse to the longitudinal direction of the first clamp leg. 
     In another embodiment of the bracket, the groove may have inclined surfaces and/or rounded areas at its distal end and at its mesial end. Two ribs may be provided in the groove on the wall facing away from the clamp bend. The ribs may be on the gingival wall and extend in the lingual-labial direction. The ribs may have chamfered or rounded edges. The ribs make it possible to very easily vary the width of the slit measured in the gingival-occlusal direction while manufacturing the bracket. The clamp—in particular the first clamp leg—can have a rounded edge. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Additional details and advantages of the invention are disclosed in the following description of several illustrative embodiments in conjunction with the attached figures: 
         FIG. 1  is a perspective view of a first embodiment of a bracket according to the invention with a clamp in the open position; 
         FIG. 2  is a view of the bracket in the direction of arrow II in  FIG. 1 ; 
         FIG. 3  is a view of the bracket cut along the cut surface III-III in  FIG. 2 ; 
         FIG. 4  is an oblique view of the bracket cut along the cut surface IV-IV in  FIG. 3 ; 
         FIG. 5  is an oblique view of the bracket cut along the cut surface V-V in  FIG. 3 ; 
         FIG. 6  shows the bracket of  FIG. 1  in a view corresponding to the latter, wherein the clamp is in the closed position; 
         FIG. 7  shows the bracket according to  FIG. 6  in a view corresponding to  FIG. 3 ; 
         FIG. 8  shows the bracket of  FIG. 3  in a view corresponding to the latter, wherein the clamp has not yet been inserted; 
         FIG. 9  shows the bracket according to  FIG. 8  in a view corresponding to  FIG. 2 ; 
         FIG. 10  shows the bracket according to  FIG. 8  in a view corresponding to  FIG. 4 ; 
         FIG. 11  shows the bracket of  FIG. 3  in a view corresponding to the latter, wherein the clamp is partially inserted; 
         FIG. 12  shows the bracket according to  FIG. 11  in a view corresponding to  FIG. 2 ; 
         FIG. 13  shows the bracket according to  FIG. 11  in a view corresponding to  FIG. 4 ; 
         FIG. 14  is a view of the bracket cut along the cut surface XIV-XIV in  FIG. 11 ; 
         FIG. 15  is a perspective view of a second embodiment of the bracket according to the invention with a clamp in the open position; 
         FIG. 16  is a view of the bracket in the direction of arrow XVI in  FIG. 15 ; 
         FIG. 17  is a view of the bracket cut along the cut surface XVII-XVII in  FIG. 16 ; 
         FIG. 18  is an oblique view of the bracket cut along the cut surface XVIII-XVIII in  FIG. 17 ; 
         FIG. 19  is an oblique view of the bracket cut along the cut surface XIX-XIX in  FIG. 17 ; 
         FIG. 20  shows the bracket of  FIG. 15  in a view corresponding to the latter, wherein the clamp is in the closed position; 
         FIG. 21  shows the bracket according to  FIG. 20  in a view corresponding to  FIG. 17 , 
         FIG. 22  shows the bracket of  FIG. 17  in a view corresponding to the latter, wherein the clamp has not yet been inserted, 
         FIG. 23  shows the bracket according to  FIG. 22  in a view corresponding to  FIG. 16 , 
         FIG. 24  shows the bracket according to  FIG. 22  in a view corresponding to  FIG. 18 , 
         FIG. 25  shows the bracket on  FIG. 17  in a view corresponding to the latter, wherein the clamp is partially inserted, 
         FIG. 26  shows the bracket according to  FIG. 25  in a view corresponding to  FIG. 16 ; 
         FIG. 27  shows the bracket according to  FIG. 25  in a view corresponding to  FIG. 18 ; 
         FIG. 28  is a view of the bracket cut along the cut surface XXVIII-XXVIII in  FIG. 25 ; 
         FIG. 29  is a perspective view of a third embodiment of the bracket according to the invention with a clamp in the open position; 
         FIG. 30  is a view of the bracket in the direction of arrow XXX in  FIG. 29 ; 
         FIG. 31  is a view of the bracket cut along the cut surface XXXI-XXXI in  FIG. 30 ; 
         FIG. 32  is an oblique view of the bracket cut along the cut surface XXXII-XXXII in  FIG. 31 ; 
         FIG. 33  is an oblique view of the bracket cut along the cut surface XXXIII-XXXIII in  FIG. 31 ; 
         FIG. 34  shows the bracket of  FIG. 29  in a view corresponding to the latter, wherein the clamp is in the closed position; 
         FIG. 35  shows the bracket according to  FIG. 34  in a view corresponding to  FIG. 31 ; 
         FIG. 36  shows the bracket of  FIG. 31  in a view corresponding to the latter, wherein the clamp has not yet been inserted; 
         FIG. 37  shows the bracket according to  FIG. 36  in a view corresponding to  FIG. 30 ; 
         FIG. 38  shows the bracket according to  FIG. 36  in a view corresponding to  FIG. 32 ; 
         FIG. 39  shows the bracket of  FIG. 31  in a view corresponding to the latter, wherein the clamp is partially inserted; 
         FIG. 40  shows the bracket according to  FIG. 39  in a view corresponding to  FIG. 30 ; 
         FIG. 41  shows the bracket according to  FIG. 39  in a view corresponding to  FIG. 32 ; and 
         FIG. 42  is a view of the bracket cut along the cut surface XLII-XLII on  FIG. 39 . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       FIGS. 1 to 42  show three embodiments of a bracket  1  according to the invention. The bracket  1  according to the invention has a curved fastening side  2 , whose curvature is approximated to the vestibular side of a tooth (not shown). Projections  3  arranged in rows are present on the fastening side  2 . An adhesive can be applied to the fastening side, so as to adhesively bond the bracket  1  to the vestibular side of a tooth. The fastening side  2  thus comprises the lingual side of the bracket  1 . In a bracket to be adhesively bonded to the lingual side of a tooth, the indications “lingual” and “labial” must be switched accordingly. The bracket  1  has a socket  4 , from which a gingival wall  5  and an occlusal wall proceed. The two walls  5  and  6  run parallel to each other, and are separated by a groove  7  that runs continuously along a straight line from distal to mesial, and is labially open. Two ligature wings  8  protruding in a gingival direction are provided on the gingival wall  5 . Two ligature wings  9  protruding in an occlusal direction are provided on the occlusal wall  6 . As a consequence, the orientation provided for the bracket on a tooth is as follows on  FIG. 3  with respect to the directions: bottom lingual, top labial, right occlusal, left gingival and distal-mesial perpendicular to the drawing plane. 
     The groove  7  is designed to receive an archwire (not shown), which usually has a rectangular cross section and is not part of the bracket. By preloading the archwire, a torque can be exerted on the base  11  of the groove  7  and on the walls  5  and  6 . To this end, the clear cross section of the groove  7  is generally rectangular. In the present case, the clear cross section is bordered by the base  11  of the groove  7  as well as by ribs  12  on the gingival wall  5 , which serve to diminish the friction of the archwire in the groove  7 . The base  11  extends continuously without interruption from mesial to distal, see  FIGS. 14, 28 and 42 . Provided at the ends of the groove  7  are rounded inclined surfaces  14  on the base  11 , rounded inclined surfaces  15  on the gingival wall  5  and rounded inclined surfaces on the occlusal wall  6 , which widen the entry of the groove  7 , and likewise serve to diminish the friction for the archwire lying in the groove  7 . This can be advantageous in particular given severely misaligned teeth, which require an especially irregular progression of the archwire. 
     A slit  18  runs underneath the base  11  of the groove  7  parallel to the base  11 , and is bordered by a lingually situated surface  19  and a labially situated surface  20 , as well as by two narrow side walls  21 . The side walls  21  run parallel to each other, and extend between the lingually situated surface  19  and the labially situated surface  20 . The slit  18  extends continuously through the socket  4 , and is not connected with the groove  7 . 
     The bracket  1  also comprises a clamp  25  made out of a spring material. It has a first clamp leg  26  that runs in a straight line and a second clamp leg  27  that is shorter than the first clamp leg  26  and runs approximately in a straight line. The first clamp leg  26  is the lingual leg, and the second clamp leg  27  is the labial leg. The two clamp legs  26 ,  27  are connected by a section that runs in an approximately circular arc, which is referred to as the clamp bend  28 . In the case depicted, the clamp bend  28  forms an occlusally arranged section of the clamp  25 . The latter is exactly as wide as the first clamp leg  26 , which fits into the slit  18  with little play. The second clamp leg  27  widens to approximately the length of the groove  7 . It does not run parallel, but rather at an acute angle to the first clamp leg  26 , which it approaches from the clamp bend  28 . The gingival end of the second clamp leg  27  has a gingivally extending extension  29 , which is angled in a labial direction. The extension  29  is narrower than the second clamp leg  27 , and narrower than the first clamp leg  26 ; it fits with little play in a cutout  24  arranged in the gingival wall  5 . The clamp  25  is connected with the bracket  1  by introducing the clamp leg  26  from an occlusal direction into the slit  18 , see  FIGS. 8, 22 and 36 , and pushing it forward in a gingival direction until in the closed position of the clamp  25 , see  FIGS. 7, 21 and 35 . For opening purposes, the clamp  25  is pushed back until it is in its open position, see  FIGS. 3, 17 and 31 . Given a bracket to be adhesively bonded to a tooth in the opposite direction, the clamp bend  28  can form a gingivally situated section of the clamp  25 , and the indications “occlusal” and “gingival” are to be switched accordingly. 
     In the first embodiment of the bracket  1  shown in  FIGS. 1 to 14 , the first clamp leg  26  has an oblong recess  30 . The recess  30  is designed as an oblong hole, and centrally arranged in the first clamp leg  26 . A projection  31  that proceeds from the labially situated surface  20  of the slit  18  protrudes lingually into the recess  30 . The labially situated surface  20  is designed as a flat guiding surface  20   a  for the first clamp leg  26 . The projection  31  is shaped like a latching lug. The (occlusal) side of the projection  31  facing the clamp bend ( 28 ) runs inclined at an angle of roughly 20° to the guiding surface  20   a.  The (gingival) side of the projection  31  facing away from the clamp bend ( 28 ) is inclined more strongly toward the guiding surface  20   a  than the side facing the clamp bend ( 28 ). The projection  31  is molded in one piece on the socket  4 . The (gingival) end of the recess  30  facing away from the clamp bend ( 28 ) is bordered by a stop  33 , which is formed by the mesially to distally running web at the free (gingival) end  26   a  of the first clamp leg  26 . The lingually situated surface  19  of the slit  18  contains two flat guiding surfaces  19   a  and  19   b  for the first clamp leg  26 , between which a channel  35  is arranged. The guiding surfaces  19   a,    19   b  run parallel to the guiding surface  20   a.  The guiding surfaces  19   a,    19   b  and the channel  35  extend from gingival to occlusal over the entire length of the slit  18 . When starting to introduce the clamp  5  into the slit  18 , the free end  26   a  of the first clamp leg  26  sits before the projection  31 , see  FIGS. 8 to 10 . When the stop  33  reaches the projection  31  while continuing to insert the first clamp leg  26  into the slit  18 , the first clamp leg  26  is resiliently deformed in the lingual direction with the stop  33 , see in particular  FIGS. 11 to 14 . The channel  35  in the lingually situated surface  19  forms an escape space  36  in the surface  19  lying opposite the projection  31 . The first clamp leg  26  with the stop  33  can thus escape into the escape space  36  when the stop  33  slides over the projection  31  while inserting the clamp  25 . In the area of the stop  33 , the guiding surfaces  19   a,    19   b  and the projection  31  here bend the first clamp leg  26  around a straight line, which runs along the longitudinal direction of the first clamp leg  26  in the gingival-occlusal direction, see in particular  FIGS. 12 and 14 . Once the stop  33  has been pushed over the projection  31 , the first clamp leg  26  springs back into its flat initial shape, see  FIGS. 2 to 4 . If the first clamp leg  26  is pushed further in the direction of the closed position, the projection  31  does not impede the movement, since the projection  31  finds room in the recess  30 . If the first clamp leg  26  has been completely pushed into the slit  18 , the clamp  25  is in its closed position, see  FIGS. 6 and 7 . For moving the clamp  25  from the closed position into the open position, the second clamp leg  27  has a hole  40 , which a pin-shaped tool (not shown) can engage. In addition, a positioning aid  41  for a tool (not shown) is provided before the free end  26   a  of the first clamp leg  26 , with which the clamp  25  can be moved from the closed position into the open position by pressing against the free end  26   a  of its first clamp leg  26 . In each position of the clamp  25 , in particular in its closed position (see  FIG. 7 ), the surface  19  that borders the slit  18  and is situated on the side of the first clamp leg  26  facing away from the groove  7  protrudes over the free end  26   a  of the first clamp leg  26 . In order to move the clamp  25  out of its closed position (see  FIG. 7 ) into its open position (see  FIG. 3 ), a tool (not shown) is taken to hand, for example a scaler, and applied to the free end  26   a  of the first clamp leg  26 . This position can be palpated without having to see it, because the lingually situated surface  19  extends so far in the gingival direction as to protrude over the free end  26   a  of the first clamp leg  26 . In addition, a channel  41  extending until under the first clamp leg  26  is located in the lingually situated surface  19 , proceeding from its gingival end. The channel  41  narrows in the gingival to occlusal direction, and ends at a stop  42 . The channel  41  serves as a positioning aid for the tool (not shown), with which the channel  41  can be palpated. Once the recess  41  has been palpated, the tip of the tool is used to move the clamp  25  in the gingival to occlusal direction. The tip of the tool here continues to be guided in the correct direction by the channel  41 . The sliding movement ends when the stop  33  hits the projection  31 , see  FIG. 3 . The clamp  25  is then in its open position. In this open position, the second clamp leg  27  has a resting position on the occlusal wall  6 , in which it opens up access to the groove  7  from a labial direction. 
     In the second embodiment of the bracket  1  shown in  FIGS. 15 to 28 , the mesial edge and distal edge of the first clamp leg  26  each have a recess  30   a,    30   b.  A projection  31   a  proceeding from the labially situated surface  20  protrudes into the recess  30   a.  A projection  31   b  proceeding from the labially situated surface  20  protrudes into the recess  30   b.  An escape space  36  is allocated in the list  18  opposite the projection  31   a , designed like a channel  35   a,  and extends from gingival to occlusal over the entire length of the slit  18 . An escape space  36  is provided in the slit  18  opposite the projection  31   b.  The escape space  36  is formed as a channel  35   b  that extends from gingival to occlusal over the entire length of the slit  18 . The labially situated surface  20  of the slit is designed as a flat guiding surface  20   a,  from which the two projections  31   a ,  31   b  proceed. The lingually situated surface  19  of the slit  18  contains a flat guiding surface  19   a  for the first clamp leg  26 , which is arranged between the two channels  35   a  and  35   b.  As in the first embodiment, during the insertion of the first clamp leg  26  into the slit  18 , the first clamp leg  26  with the two stops  33   a  and  33   b  resiliently escapes into the respective escape space  36   a  and  36   b  (see  FIGS. 25 to 28 ) while the stops  33   a,    33   b  slide over the projections  31   a  and  31   b  during insertion of the clamp  25  into the slit  18 . In the area of the stops  33   a,    33   b,  the projections  31   a  and  31   b  and the guiding surfaces  19   a  here bend the first clamp leg  26  around a straight line, which runs along the longitudinal direction of the first clamp leg  26  in the gingival-occlusal direction, see  FIGS. 26 and 28 . Here as well, the bend of the first clamp leg  25  again reverses once the stops  33   a,    33   b  have been pushed over the projections  31   a  and  31   b,  see  FIGS. 16 to 18 . When the clamp  25  is moved between the open position (see  FIG. 17 ) and the closed position (see  FIG. 21 ), the projections  31   a,    31   b  protrude into the recesses  30   a ,  30   b,  and do not impede the movement. In order to move the clamp  25  from the closed position into the open position, the second clamp leg  27  has a hole  40 , into which a pin-shaped tool (not shown) can engage. The functional principle of the second embodiment otherwise corresponds to that of the first embodiment, so that reference is made thereto so as to avoid repetition. 
     In the third embodiment of the backet  1  according to the invention shown on  FIGS. 29 to 42 , the first clamp leg  26  has an oblong recess  30  that is T-shaped in design. A projection  31  proceeding from the labially situated surface  20  lingually protrudes into the latter. The labially situated surface  20  is designed as a flat guiding surface  20   a.  The lingually situated surface  19  contains a flat guiding surface  19   a.  A pocket  37  is formed in the lingually situated surface  19  as an escape space  36 . The pocket  37  extends over the entire width of the slit  18 , see  FIG. 33 . As in the first exemplary embodiment, during the insertion of the first clamp leg  26  into the slit  18 , the first clamp leg  26  with the stop  33  resiliently escapes into the escape space  36  (see  FIGS. 39 to 42 ) while the stop  30  slides over the projection  31  during insertion of the clamp  25  into the slit  18 . In the area of the stop  33 , the projection  31  here bends the first clamp leg around a straight line, which runs transverse to the longitudinal direction of the first clamp leg  26 , i.e., in the mesial-distal direction. As in the first embodiment, the bend of the first clamp leg again reverses once the stop  33  has been pushed over the projection  31 , see  FIGS. 30 to 32 . The functional principle of the third exemplary embodiment otherwise corresponds to that of the first exemplary embodiment, so that reference is made thereto so as to avoid repetition. 
     REFERENCE LIST 
       1  Bracket 
       2  Fastening side 
       3  Projections 
       4  Socket 
       5  Gingival wall 
       6  Occlusal wall 
       7  Groove 
       8  Gingival ligature wing 
       9  Occlusal ligature wing 
       10  Base of  7   
       11  Ribs on  5   
       14  Inclined surfaces on  11   
       15  Inclined surfaces on  5   
       18  Slit 
       19  Lingually situated surface 
       19   a  Guiding surface 
       19   b  Guiding surface 
       20  Labially situated surface 
       20   a  Guiding surface 
       21  Side walls 
       24  Cutout 
       25  Clamp 
       26  First clamp leg 
       26   a  Free end 
       27  Second clamp leg 
       28  Clamp bend 
       29  Extension from  27   
       30  Recess 
       30   a  Recess 
       30   b  Recess 
       31  Projection 
       31   a  Projection 
       31   b  Projection 
       33  Stop 
       33   a  Stop 
       33   b  Stop 
       35  Channel 
       35   a  Channel 
       35   b  Channel 
       36  Escape space 
       37  Pocket 
       40  Hole in  27   
       41  Channel (positioning aid) 
       42  Stop