Nickel-titanium NiTi tools are much more flexible suitable for curved and narrow canal which , have better cutting capacity, they
have a shape memory (always return to their original shape).
Manual files NiTi type K (Kerr) best for finding canals and working the thin root canals. With a tightly twisted steel spiral, four cutting edges (low ability of cutting), flexible – provide safety. Low ability to transport outside the cut dentin. Files can be re-sterilized in a steam autoclave at 134 degrees C
