introduction: the purpose of this in-vitro study was to compare shaping ability of niti rotary mtwo and flexmaster with stainless steel hand k-flexofile in curved root canals of extracted teeth. materials and methods: mesiobuccal canals of 45 mandibular molar teeth were balanced into three groups of 15 each, with respect to the schneider angle, canal access angle, height, dis-tance and radius o...