the slide 13 which the slide 13 cannot leave in labial direction because the undercuts 16 prevent it the recesses 14 and 15 lie in a common alignment the recess 14 runs through the gingival wall 5 while the recess 15 ends against a stop 18 in the occlusal wall 6 i e the u201c second u201d stop mentioned in the patent claims the slide 13 can be displaced in the guide 15 to 17 in the gingival occlusal direction between an open position which is represented on fig4 and a closed position which is illustrated in fig2 3 and 5 in open position the slot 7 is open over its whole width from the labial side the front end 19 of the slide 13 closes preferably with the surface of the gingival wall 5 delineating the slot 7 as illustrated in fig2 and 7 in closed position the front end 19 of the slide 13 strikes against the second stop 18 on the occlusal wall 6 such as it is illustrated particularly clearly on fig3 in closed position the slide 13 bridges the slot 7 so that an archwire 10 running therein cannot leave the slot 7 in labial direction the gingival wall 5 includes a slit shaped recess 21 which extends mainly in parallel to the surface of the wall 5 delineating the slot 7 the surfaces 21 a and 21 b extending in direction of the slot 7 opposite to one another.