Comparison of Cyclic Fatigue Resistance of Three Different Rotary Nickel-Titanium Instruments Designed for Retreatment
Ugur Inan, DDS, PhD, and Cumhur Aydin, DDS, PhD
Introduction: A number of rotary nickel-titanium (NiTi)
systems have been developed to provide better, faster,
and easier cleaning and shaping of the root canal
system, and recently, rotary NiTi systems designed for
root canal retreatment have been introduced. Because
the main problem with the rotary NiTi files is fracture,
the aim of this study was to compare the cyclic fatigue
resistance of 3 different rotary NiTi systems designed
for root canal retreatment. Methods: Total of 60 instruments of 3 different rotary NiTi systems designed for
root canal retreatment were used in this study. Twenty
R-Endo R3, 20 ProTaper D3, and 20 Mtwo R (Retreat-
ment) 25.05 instruments were tested. Cyclic fatigue
testing of instruments was performed by using a device
that allowed the instruments to rotate freely inside an
artificial canal. Each instrument was rotated until frac-
ture occurred, and the number of cycles to fracture for
each instrument was calculated. Representative
samples were also evaluated under a scanning electron
microscope to confirm the fracture was flexural. Data
were analyzed by using 1-way analysis of variance
test. Results: R-Endo R3 instruments showed better
cyclic fatigue resistance than ProTaper D3 and Mtwo R
25.05 instruments, and the difference was statistically
significant (P < .05). There was no significant difference
between ProTaper D3 and Mtwo R 25.05 groups.
Conclusions: The R-Endo R3 instruments were more
resistant to fatigue failure than ProTaper D3 and
Mtwo R 25.05.
(J Endod 2012;38:108–111)
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