Blue Heat Treatment

Blue heat treatment produces a distinctive cobalt-blue oxide surface by heating NiTi wire to 450–500°C. Like Gold treatment, it elevates the Af temperature above body temperature, yielding a predominantly martensitic alloy at 37°C. The resulting files are highly flexible and exhibit a unique 'pre-bend' memory: they can be bent by hand and retain a gentle curve that aids insertion into curved canals. Manufacturers report a minimum 40–65% improvement in cyclic fatigue resistance versus conventional M-Wire, depending on the system. Blue-treated files are well suited to single-file reciprocating techniques where fatigue life is particularly important.