To compare the performance of ProTaper(r) rotary instruments and stainless steel K-Flexofiles in preparing curved root canals in terms of changes in angle of curvature, apical transportation and production of canal aberrations and also to record the rate of separation of ProTaper(r) files. ProTaper(r) rotary instruments maintained the curvatures better however it performed equally in terms of apical canal transportation when compared with stainless-steel instruments. For procedural errors and canal aberrations, ProTaper(r) instruments produced more elbows. Incidence of fractures was enhanced...