Kumar S, Ratnakar P, Chakka NM, Das S, Bagchi A.
Do NiTi Instruments show Defects before Separation? Defects caused by Torsional Fatigue in Hand and Rotary Nickel-Titanium (NiTi) Instruments which Lead to Failure during Clinical Use. 
J Contemp Dent Pract
2012;
13
(6):867-872.