This appliance uses a nickel titanium coil spring -- activated by an adjustable Gurin Lock -- to regain space without tipping or rotating the teeth. The amount of reciprocal movement of the molar distally and the bicuspid mesially will be effected by the proximity of the adjacent teeth. In order to restrict the movement of one of the abutment teeth, it is necessary to add additional anchorage. Using a jackscrew with labial/lingual arch wires, will accomplish this. A small dab of premixed cold-cure acrylic may also be applied to the threads behind the second nut to further ensure that the screw maintains its force and does not back up. Activating the Gurin Lock is easily accomplished with a special box wrench (available from SML).