A Comparative Study Of The Effectiveness Of Instrumentation Techniques For Cleaning The Fine Curved Canal Of Posterior Teeth

Objective The aim of this study was to compare the effectiveness of three instrumentation techniques for cleaning the fine curved canals of posterior teetir. Methods Forty-five mesiobuccal root canals in fleshly extracted n u a a n molar teeth were instrumented by the step-back technique , the step-down technique or the passive step-back technique. The time of preparation of each canal was taken notes. After cracking the rcots longitudinally, the canals walls were observed under a scanning electron microscope ana the coronal, middles and apical thirds of each canal were photographed at a magnification of 1000 and 100. Each canal was qualitatively evaluated andthe groups were compared for removal of debris and smear layer, both overall and at each level (apica1, midd1e , and coronal).Results There were no statistically significant differences between the techniques either overall or within any of the regions. When comparing regions(regardless oftechnique), the apical portion of the canal was less clean than the middle or coronal portionsConclusions Efficacy differed little among the techniques.None of the three techniques completely removed smear layer and all left debris,especial1y within the apical third of the canals.The passive step-back technique was superior to the step-back and step-down techniques when it was related to the cleaning efficiency,but it took a longer time for preparation and was so exhausted. The step-down technique can be used more easyly within a short time.