Rapid palatal suture - expansion apparatus, which comprises an adjusting element (2), which, together with an actuating head (3) and two shafts (4) with opposite screw threads as well as a first and a second main body (5, 6), with the female screws (7, 8) are provided, which is provided and in each case aligned with a threaded shaft (4) of the adjusting element (2) are connected. There are guide means (9) is provided, in order to the simultaneous displacement of the main body (5, 6) along the longitudinal direction y of the course of the adjusting element (2) in the connection to the rotation of the actuating head (3) to guide and rotationally secured devices, in order to the rotation of the actuating head (3) in the second direction of rotation in the direction opposite to the first to prevent the the closing of the expansion device (1) serves. These rotary a safeguard against directions comprise a plurality of longitudinal seats (61) on an outer surface (3a) of the actuating head (3), each of which comprises a blocking surface (62), the at least partially into the second direction of rotation is directed. In addition, the directions of rotation of the protection against a plate (64), which are mechanically rigidly to one of the two main body (5, 6), and is connected by a flexible plate (65) is provided, the elastically on the outer surface (3a) of the actuating head (3) on the entire adjustment stroke of the main body (5, 6) and rests with its own profile (65 ’) selectively into the has longitudinal seats (61) of the head (3) on the angular positions of the adjustment, can engage the from the latter along of the one bearing member stroke to be assumed.
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