Controlled Memory Wire (CM-Wire) undergoes a specialized heat treatment at 450–550°C that dramatically alters the shape-memory behavior of NiTi. The result is an alloy with near-zero shape memory at room and body temperatures: unlike conventional or M-Wire NiTi, CM-Wire files can be bent by hand and retain the deformed shape permanently, much like stainless steel. This property makes them ideal for pre-bending to match canal curvature before insertion. Despite the loss of shape memory, CM-Wire maintains excellent superelastic flexibility and offers substantially greater cyclic fatigue resistance than conventional NiTi. Files can often be regenerated (returned to original shape) by autoclaving.
Metallurgical Properties
Af Temperature45–55°C
Phase at 37°CMartensite (near-zero shape memory)
FlexibilityVery High (pre-bendable, retains set)
Cyclic FatigueUp to 300–700% greater than conventional