Patent ID: 7837465

Claim:
Orthodontic expansion screw comprising: two bodies whose distance from each other can be changed by means of a spindle that engages both bodies, whereby the spindle comprises an actuation part by means of which a torque can be effected for readjusting the spindle: straight-line guiding means for engaging both bodies and guiding the bodies along two guide axes that are parallel to each other while preventing a relative rotation of the bodies when their distance from each other is being changed, the guiding means including two guide pins disposed parallel to the spindle and on opposite sides thereof; and a friction brake including a metal ribbon extending transverse to the guide axis over the spindle and connected to the two guide pins, the ribbon pressing onto the actuation part of the spindle for generating a frictional force that renders a rotation of the spindle in both directions of rotation more difficult in order to prevent inadvertent readjustment of the spindle, wherein the actuation part has two transverse bore holes that intersect at a right angle and the external cross-section of the actuation part deviates from a circular shape such that the frictional force generated by the friction brake depends on the spindle's angular position of rotation.