This sliding metal press machine was used for the prefabrication of the Johnson twin wire arch. It is a small, heavy metal press, with a central lever that moves back and forth to close press.
Two 0.25mm arches would be passed through a tube 0.5mm in diameter and the ends were crinkled and drawn through the tube to secure them. It was important to keep the two wires parallel. Clinically these tubes in turn had a sliding fit into tubes welded/soldered to molar bands. The jig allowed the wires to have parallel alignment as they were pulled into the tubes and held with a friction fit. The parallel wires sitting at the base of the slots on the incisor attachments were mechanically advantageous in terms of tooth control.
The concept was devised by the American orthodontist J.E. Johnson. It was excellent for correcting incisor rotations. The twin wires gave gentle force with a long range of action and the tubes gave support for the delicate wires when unsupported between the molars and incisors.
Johnson twin wire arch press