Table 1. Nickel-titanium (NiTi) retreatment instruments used in this study.

NiTi file	Manufacturer	ISO tip size, taper	Length (mm)	Speed (rpm)	Maximum torque (N·cm)
DR1	FKG Dentaire, La Chaux-de-Fonds, Switzerland	Size 30, 10% taper	15	800	1.5
DR2		Size 25, 4% taper	25	400	1.5
HyFlex Remover	Coltene/Whaledent AG, Altstätten, Switzerland	Size 30, 7% taper	19	400	2.5
Mtwo R25/05	VDW, Munich, Germany	Size 25, 5% taper	21	300	1.2