Laboratory Construction Procedure

Initially, the screw thread housings, which incorporate 12mm advancement screws, are positioned on the cast model through a wax dam, and aligned relative to the occlusal plane and midline, using the alignment rods.

The Twin Block is then constructed in the usual way (self cure or heat cure), incorporating the screw thread housings and screws into the mesial face of each upper block of the appliance.

The specially machined conical heads give an included angle of 140 degrees. This ensures that when positioned longitudinally in the block, the screw head will present a 70 degree angle with the face of the lower block, regardless of the rotational position of the screw.