wire  1. a long, slender, flexible structure of metal, used in surgery and dentistry. 2. to insert such strands into a body structure, as into a broken bone to immobilize fragments, or into an aneurysm to promote clot formation. arch wire, a wire attached to molar bands or an orthodontic appliance and applied around the dental arch to control and force tooth movement in orthodontic therapy. Called also orthodontic w. arch wire, ideal, the configuration of an arch wire that conforms as closely as possible to the desired ultimate shape of the arch for a particular individual. Kirschner wire, a steel wire for skeletal fixation of fractured bones and for obtaining skeletal traction in fractures; it is inserted through the soft tissues and the bone. ligature wire, a soft, thin wire used to tie an arch wire to band attachments or brackets in an orthodontic appliance. orthodontic wire, arch w. separating wire, a brass wire threaded between two teeth having tight contact in an effort to wedge them slightly apart before fitting a band in the application of an orthodontic appliance. twin wire, see under appliance.