Cleaning and shaping of root canals is the most important aspect of successful Endodontic therapy. An ideally prepared root canal should be tapered from crown to apex without deviation from the original canal curvature and the apical constriction should be maintained. However, it is very difficult to get a desirable canal shape in narrow and curved canals. The preparation of curved root canals with stainless steel instruments frequently results in undesirable aberrations and such as zips, elbows, ledges, straightening of curved canals, loss of working lengths, perforations, apical blockages or instrument fractures. Several preparation techniques have been described to solve some of these problems and also some modifications in configuration for root canal instruments have been recommended recently. The automated systems have been developed in order to decrease the tiredness of patient and operator and to time-consuming process of cleaning and shaping the root canal system. In recent years, several new nickel-titanium instruments for manual root canal preparation, as well as for use in a rotary endodontic handpiece, have been developed in order to facilitate the difficult process of cleaning and shaping the root canal system and to improve the final quality of root canal preparation. These mechanical systems are being used increasingly in preference to classical manual methods.