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


METHODS
Simulated 28 degree- and 35 degree-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 bet-ter 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.
Schäfer
E
E
Department of Operative Dentistry, University of Münster, Münster, Germany. eschaef@uni-muenster.de
Lohmann
D
D
D003762:Dental Instruments; D004526:Efficiency; D004867:Equipment Design; D004868:Equipment Failure; D006801:Humans; D003765:Models, Dental; D009532:Nickel; D018915:Root Canal Preparation / Q000295:instrumentation*; D013193:Stainless Steel; D018709:Statistics, Nonparametric; D013997:Time Factors; D014025:Titanium
C040654:titanium nickelide; D013193:Stainless Steel; D009532:Nickel; D014025:Titanium