Efficiency of rotary nickel-titanium FlexMaster instruments compared with stainless steel hand K-Flexofile -: Part 1.: Shaping ability in simulated curved canals

Aim The purpose of this study was to compare the shaping ability of FlexMaster rotary nickel-titanium instruments with stainless steel hand K-Flexofiles. This part of the two-part report describes the efficiency of these two instruments in simulated curved root canals. Methodology Simulated 28degrees- and 35degrees-curved canals were prepared by the FlexMaster instruments with a rotational speed of 250 rpm using a crown-down preparation technique, and by the K-Flexofiles using a reaming motion (n = 24 canals in each case). All canals were prepared up to size 35. The pre- and post-instrumentation images were recorded and assessment of the canal shape was completed with a computer image analysis program. The material removal was measured at 20 measuring points, beginning 1 mm away from the apex. Incidence of canal aberrations, preparation time, changes of working length and instrument failures were also recorded. Results In comparison with stainless steel K-Flexofiles, the rotary FlexMaster instruments achieved better canal geometry, showed less canal transportation and created fewer canal aberrations in both the canal types. Two FlexMaster instruments were separated, and 15 FlexMaster instruments and 11 K-Flexofiles were permanently deformed during preparation. However, these differences were not significant (P > 0.05). Between both the canal types, FlexMaster was significantly faster (P < 0.001) than K-Flexofiles. Both instruments maintained a good working distance. Conclusions FlexMaster instruments prepared curved canals rapidly, and with minimal transportation towards the outer aspect of the curve.