Change of working length in curved molar root canals after preparation with different rotary nickel-titanium instruments.

Aim: The purpose of this study was to investigate change of working length in curved molar root canals after preparation with Profile, ProTaper and K3 Rotary Nickel-Titanium (Ni-Ti) instruments.

Materials And Methods: One hundred and eighty maxillary and mandibular molars were divided into group I having root curvature angle <300 and group II having root curvature angle >300 comprising 90 teeth in each group based on Schneider's method. Group II and I were further divided into sub group A, B and C having 30 teeth each based on type of instrument used.