Comparative evaluation of the shaping ability of ProTaper Next, iRaCe and Hyflex CM rotary NiTi files in severely curved root canals.
OBJECTIVE
To compare the shaping ability of ProTaper Next, iRaCe and Hyflex CM rotary NiTi files during the preparation of severely curved root canals in extracted human molar teeth.


METHODS
Sixty mandibular molars with mesio-buccal canals having angles of curvature ranging from 25° to 35° were divided according to the instrument used into three groups of 20 teeth each: group PTN (ProTaper Next), group IR (iRaCe) and group HF (Hyflex CM). Using standardized pre- and post-instrumentation radiographs, straightening of canal curvature was determined using image analysis software. A double-digital standardized radiographic technique was used to determine apical transportation 0.5 mm from the working length (1.5-mm coronal of the major foramen). Preparation time and instrument failures were also recorded. Data were analysed using one-way analysis of variance (anova) and post hoc Tukey's test, and significance was set at P < 0.05.


RESULTS
During root canal preparation, no instruments fractured. The use of PTN resulted in significantly greater canal straightening than IR and HF (P < 0.05), with no significant differences between IR and HF (P > 0.05). There were no significant differences between the three groups with respect to apical transportation (P > 0.05). IR and HF were significantly faster than PTN (P < 0.05), with no significant differences between IR and HF (P > 0.05).


CONCLUSIONS
Under the conditions of this study, PTN, IR and HF respected original canal curvature well and were safe to use.
Department of Endodontics, Faculty of Dentistry, Ain Shams University, Cairo, Egypt.
S E D M
SE
Saber
M M
MM
Nagy
E
E
Schäfer
D003762:Dental Instruments; D004867:Equipment Design; D004868:Equipment Failure; D006801:Humans; D066298:In Vitro Techniques; D008963:Molar; D009532:Nickel; D018915:Root Canal Preparation / Q000295:instrumentation*; D013997:Time Factors; D014025:Titanium
C040654:titanium nickelide; D009532:Nickel; D014025:Titanium
Hyflex CM; ProTaper Next; apical transportation; canal straightening; iRaCe; shaping ability