A COMPARISON OF STAINLESS-STEEL AND NICKEL-TITANIUM K-FILES IN CURVEDROOT CANALS

The purpose of this study was to determine the effects of hand instrum entation using traditional stainless steel K-files and nickel-titanium K-files on the final shape of curved root canals. A total of 24 moder ately curved canals in the mesial roots in extracted human mandibular first molars were randomly divided into two groups. These were instrum ented manually using either stainless steel or nickel-titanium K-files with the step-down technique. The cross-sectional shape of each canal at three different horizontal levels were captured, before and after instrumentation, into a computer for comparison using image analyser s oftware. Three parameters at each level were evaluated: (i) amount of dentine removed: (ii) least remaining dentine thicknesses on mesial an d furcal aspects: and (iii) the amount and direction of canal transpor tation. The results showed that the two file types removed similar amo unts of dentine at all three levels examined. The nickel-titanium file s left a thicker layer of dentine on both the mesial and furcal aspect s than stainless steel files. However, the difference was not signific ant (pooled T-test, P>0.05). Both types of files transported the centr e of the canals but the nickel-titanium instrument seemed to be safer because of the reduced amount of transportation towards the danger are as.