A single F2 file can be safely used to the working length of curved canals at least six times under reciprocating motion, according to a study in the Journal of Endodontics (December 2010, Vol. 36:12, ...

Then, a hand file was inserted into the needle lumen, which shackled the separated instrument. The fragment of the rotary file was removed from the patient's tooth after three tries using this method, ...