INTRUSION ARC IN ORTHODONTIC:

The intrusion arch is a device for orthodontic anterior teeth intrusion, having been introduced by Burstone in 1977 for the treatment of deep bite, especially in the case of Class II division 2. But they are based on the origin of malocclusion and the patient's clinical characteristics, such as smile line, vertical dimension, predicted growth, among others. Use of this arc is governed by the principles of mechanical intrusion, which include obtaining a pure no intrusion proclination movements, therefore, necessary for successful treatment. Among these we can highlight to get a constant magnitude of force and the choice of point of application of force in the anterior segment, which would determine whether the motion would be pure intrusion or intrusion inclined. The mechanical stability of this is making it more advantageous in the treatment of deep bite in relation to treatment with extrusion of posterior teeth, which is notoriously prone to relapse. Thus, based on the principles of mechanics and its stability, several authors have developed some type of intrusion arches, using the original biomechanics, but differing mainly in the type of alloy wire and the point of application of force to the center of resistance to achieve the goals of the treatment

Casting of Wire Using a Twin Wheel Caster

A twin-wheel caster for casting thin aluminum alloy wire was designed, assembled, and tested. Molten metal was ejected from the nozzle (cross-sectional area: 4 mm2) of a crucible into a triangular groove that was machined on the outer surface of the lower wheel. The metal was solidified by the upper and lower wheels. Wire made of Al-1.2%Fe or 6061 aluminum alloy, whose cross-sectional area was smaller than 20 mm2, could be cast at a speed of 6 or 7 m/min. The upper and lower wheels were made of copper to increase the cooling rate. The diameter of the upper and lower wheels was 200 and 600 mm, respectively. The thickness of the wheels was 10 mm.