K. Nishi, TOMY Inc., Fukushima-ken, Japan
Application of Nitinol wire for orthodontics started from marketing by 3M Unitek (USA) in 1977. This wire is characterized by its lower modulus of elasticity in comparison with conventional wires made of stainless steel or Co-Cr alloy. Nitinol wire does not exhibit super elasticity so that this wire is called and categorized in “Work hardening type” distinct from “Super elastic type”. The present brand name of this wire is “Nitinol Classic Archwire”. In 1985, Tomy developed super elastic Nitinol wire “SENTALLOY” under the guidance of Tokyo Medical & Dental University, and subsequently produced “BIOFORCE SENTALLOY” having gradually increased force from in the anteriors toward the molars. Furthermore, in 1985, Tomy introduced to the market a low hysteresis wire “L&H TITAN” for prevention of patient’s pain which may be caused by stronger force than its original force set at 37 degC since the patient’s intraoral temperature arises with influence of food and drink. At this time, we would like to report our research on these wires.
