A comparison of molar root canal preparation using stainless-steel and nickel-titanium instruments

Fifty-four extracted human mandibular molars were embedded and sectioned at two levels. The reassembled mesial root canals were prepared with stainles s-steel hand K-files (Flexofiles) and either Nitiflex or Mity nickel-titani um hand K-files using a push-pull anticurvature filing technique. Each of t he three experimental groups contained 36 mesial canals randomly distribute d. Superimposed pre- and postinstrumentation cross-sectional root images we re magnified using a stereomicroscope and transferred to a computer for mea surement and statistical analysis. The direction and extent of canal center movement were evaluated. At the apical level, the groups produced no signi ficant difference of direction of canal center movement. In cervical sectio ns, all groups tended to move in a distolingual direction. The three groups , however, produced no significant difference in the cervical sections in t he extent of canal center movement. In apical sections, Nitiflex produced t he least canal center movement.