The preferred wire for initial alignment in orthodontics is the Nitinol wire because it exhibits superelasticity and shape memory, allowing for gentle, continuous forces that effectively align teeth without causing excessive discomfort. Its low stiffness and high springback make it ideal for engaging severely malaligned or crowded teeth. This wire also provides consistent force over a longer activation range, reducing the need for frequent adjustments. Compared to stainless steel or TMA wires, Nitinol promotes more efficient and biologically favorable tooth movement in the early stages of treatment.

Reference: Proffit, Contemporary Orthodontics, 6th Edition.