The introduction of Ni-Ti rotary instruments has led to great improvements in the effectiveness and the speed of root canal instrumentation even in curved roots. In order to achieve the mechanical goal of instrumentation that requires a uniformly tapered funnel preparation, several Ni-Ti systems can be used. A crown-down instrumentation sequence has been recommended for most of these rotary Ni-Ti instruments. Recently, the new Mtwo instruments design has been introduced which no longer requires a crown-down instrumentation sequence. Mtwo Ni-Ti system is a new type of Ni-Ti instruments. Mtwo instruments has its own autospecific predominance compared with the other Ni-Ti instruments system. Mtwo system has different design and utilization method. A review of Mtwo Ni-Ti instruments system was presented in this paper.
