Abstract: An adjustable orthodontic screw assembly adapted to regulate the position of human teeth comprises two limbs (1a, 1b), the adjacent first ends of said limbs being articulated together, the limbs each being adapted to be embedded in an associated part of a two-part extension plate (16), the second end of each limb having attached thereto a rotatable head member (2a, 2b), each head member being provided with a threaded hole with the threads of the threaded holes of the two head members being of opposite hand. A twin screw (4b) is in threaded engagement with the threaded holes of said rotatable head members. According to the invention, also the first end of either of said limbs (1a, 1b) has attached thereto a rotatable head member (2c, 2d) provided with a threaded hole, the threaded holes of these two head members being of opposite hand. A second twin screw (4a) is in threaded engagement with the threaded holes of the head members (2c, 2d) attached to the first ends of said limbs (1a, 1b).