ANALYSIS OF NI-TI VERSUS STAINLESS-STEEL INSTRUMENTATION IN RESIN SIMULATED CANALS

This study compared step-back preparations in curved canals of resin b locks using nickel-titanium K-files and stainless steel K-files, Forty canals in resin blocks were cross-sectioned at 3 levels: 1 to 2 mm fr om the apical foramen, middle of the curve, and coronal, Direct digita l computer images were recorded before and after instrumentation. Supe rimposition of the images combined with digital subtraction computer s oftware allowed direct measurement of area instrumented, distance of t ransportation, and shape analysis, Time for instrumentation was record ed, Results showed Ni-Ti files to cause significantly less transportat ion and remain more centered at the apical level (p < 0.05), Area remo ved by instrumentation was significantly greater for stainless steel f iles at the middle level (p < 0.05). Cross-sectional shape of the inst rumented canal was not significantly different (p < 0.05), It took sig nificantly longer to prepare a canal with Ni-Ti K-files in resin block s compared to stainless steel (p < 0.05). Resin simulated canals showe d similar results compared to canals in extracted roots using an ident ical methodology.