Potnis, S: Mechanical Properties and Surface Topography of N

Niti properties: 1.Exerts light continuous forces when deflected to relatively large distances, with minimum permanent deformation. 2.Decreases number of arch wire changes. 3.Requires less chair time. 4.Shortens treatment time required to accomplish rotations and leveling. 5.Produces less patient discomfort. Nickel-Titanium alloys contain approximately 54% Ni, 44% Ti and generally 2% or less of Co. This composition results in one-to-one atomic ratio of the major components. As with other systems, this alloy can exist in various crystallographic forms. At high temperatures, a body centered cubic lattice, referred to as the austenitic phase, is stable, whereas appropriate cooling can induce transformation to a close-packed hexagonal martensitic lattice. This transition can also be induced by application of stress. There is a volumetric change associated with the transition and an orientation relation is developed between the phases. These characteristics of the austenite to martensite phase transition result in two unique features of potential clinical relevance, shape memory and superelasticity or pseudoelasticity.