The Improved Superelastic Ni-Ti Alloy Wire in Orthodontic Treatment: Characteristics and Clinical Application

Orthodontists usually use Ni-Ti alloy wires for leveling and aligning of teeth without bending the wire. How-ever, Japanese Ni-Ti alloy wires, which are bendable and retain their unique characteristics even after bend -ing, have been developed. After several decades, improved superelastic Ni-Ti alloy wires (ISW) were introduced and have been found to be useful in the leveling stage owing to their superelasticity, shape-mem-ory effect, and low hysteresis. Moreover, despite its low stiffness, the ISW has been used in all treatment stages and in many cases, except in patients with a strong occlusal force and immediately before and after orthognathic surgery. The ISW can be used to upright molars and close spaces in extraction cases with proper bends to control force and moment. Clinicians can bend wires with two pliers connected to a heat treatment machine, which increases the stiffness of the wires and the elastic modulus of the bent region while main -ta ining its original characteristics. Furthermore, through combined use long hooks, the lower molars can be moved mesially without tipping by moment control, which has been proven using the new sensing device we invented. In this chapter, we introduce this attractive archwire and original force systems in some clinical cases. (199/200 words)