RESUMEN
The aim of the present study was to compare the quality of preparation in curved and straight root canals employing 2 techniques, i.e. the step-back technique and the technique of Goerig, Michelich and Schultz. One hundred and thirty single-rooted human teeth were employed throughout. The walls of the root canals of these teeth were painted. Following instrumentation the roots were sectioned longitudinally. The sections were observed under a stereoscopic microscope SZ40 with a grid fitted in the eyepiece. The efficacy of instrumentation was evaluated using area of paint removed as the end-point. Statistical significance of the data was tested with the chi square test employing the Epi Info 5 software. There was no statistically significant difference between techniques for straight canals. The technique of Goerig, Michelich and Schultz was more effective than the step-back technique in the apical third of curved canals.