shaping ability of niti rotary versus stainless-steel hand instruments in curved root canals of extracted teeth

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 of canal curvature. canals were prepared with mtwo, flexmaster and stainless steel hand k-flexofile according to the manufac-turers` instruction. comparing pre- and post-instrumentation radiographs, straightening of the canal curvatures was determined using autocad program. data was analyzed using one way anova and tukey hsd test. results: after instrumentation, the k-flexofile system was significantly different from mtwo and flex master systems for the mean difference of schneider angle (p=0.0001, p=0.0001), canal access angle (p=0.006, p=0.003), radius (p=0.045, p=0.015) and distance of curvature (p=0.001, p=0.001). conclusion: mtwo and flexmaster files main-tained the original canal curvatures better than the k-flexofile