A comparison of canal preparation with nickel-titanium and stainless steel instruments

Maintaining the original canal path during instrumentation is a challenge in narrow curved canals. This study compared the maintenance of the original canal path of curved root canals during instrumentation with nickel-titanium (Mac) hand files, nickel-titanium engine-driven files, and stainless steel (K-Flex) files. Canal path maintenance was determined by superimposing instrumentation radiographs over an initial file radiograph and examining for discrepancies. Nickel-titanium hand and engine-driven instruments maintained the original canal path in all cases. The incidence of deviation from the original canal path during instrumentation with stainless steel files increased with file size. The difference between nickel-titanium groups and stainless steel became statistically significant with instruments larger than size 30. In this study, nickel-titanium files were more effective in maintaining the original canal path of curved root canals when the apical preparation was enlarged beyond size 30.