Up to now, the TiNi shape-memory alloy archwire(TiNiSMA) and Stainless Steel archwire (SS) materials are employed in clinical orthodontics not only in china but also in abroad.

• SS丝的刚度较大，可为支抗牙提供充足的支抗，但由于其弹性较小，对移动牙会产生过大矫治力，以至影响牙齿的移动。