Rotary endodontic systems have greatly facilitated and accelerated the clinical work of a clinician. Overwhelmed with new information, it is very important to understand the basics of various systems in order to choose the right system for each clinical situation. Ni-Ti alloy is used in the manufacture of endodontic instruments intended for engine-driven (rotary) endodontics. It has unique super-elastic properties and is also able to adapt to the morphology of the canal. These characteristics are determined by the phase of the instrument: martensitic, R-phase or austenitic. By heat treatment, it is possible to obtain instruments in the desired phase, extending their lifespan and improving their characteristics. Improved characteristics can also be obtained by modifying the surface itself without interfering with the characteristics of the instrument core itself, which retains its properties. In addition to the design and machinig of the instrument, an important factor in extending the lifespan of the instrument is its kinematics. Rotational and reciprocating movements are the most common movements. Reciprocating movement is considered to reduce cyclic fatigue and prolong instrument lifespan. Among the newer systems that show markedly improved properties are the SAF and the XP-endo system. Their advantage is a greater adaptation to the canal morphology, mantaing canal shape, better debridement, and greater resistance to cyclic fatigue leading to better and more successful therapy.