Influence of Continuous or Reciprocating Motion on Cyclic Fatigue Resistance of 4 Different Nickel-Titanium Rotary Instruments
Eugenio Pedulla , PhD, DDS,* Nicola M. Grande, PhD, DDS,† Gianluca Plotino, PhD, DDS,† Gianluca Gambarini, PhD, DDS, MD,† and Ernesto Rapisarda, MD, DDS*
Abstract
Introduction: The aim of this study was to evaluate the
resistance to flexural fatigue of Reciproc R25 (VDW,
Munich, Germany), WaveOne Primary (VDW, Munich,
Germany), Mtwo (Sweden & Martina, Padova, Italy),
and Twisted File (TF; SybronEndo, Orange, CA) instruments used in continuous rotation or in 2 different
reciprocating motions. Methods: A total of 180
nickel-titanium files from 4 brands marketed, 2 for use
in reciprocating motion (ie, Reciproc R25 and WaveOne
Primary) and 2 for use in continuous rotation (ie, Mtwo
and TF both taper .06/0.25 tip diameter), were tested.
Forty-five instruments for each brand were divided
into 3 groups (n = 15) on the basis of the motion tested:
continuous rotation (group 1: 300 rpm) and reciprocal
motion (group 2: ‘‘RECIPROC ALL’’ mode and group 3:
‘‘WAVEONE ALL’’ mode). The resistance to cyclic fatigue
was determined by counting the number of cycles to
failure in a 60 curve with a 5-mm radius. Data were
analyzed through 2-way analyses of variance. Results:
The cyclic fatigue resistance of the 2 reciprocating
motion instruments (ie, ‘‘RECIPROC ALL’’ and ‘‘WAVE-
ONE ALL’’) was significantly higher than the continuous
rotation in each brand (P < .001). No significant differ-
ence was observed in cyclic fatigue between the 2
different reciprocal motions tested in each brand
(P > .05). When considering the appropriate clinical
motion for each brand, no significant difference in cyclic
fatigue was found between TF, Mtwo, and Reciproc R25
instruments, whereas the cyclic fatigue resistance
of WaveOne files was less than the other 3 brands
(P < .05). Conclusions: Reciprocal motion showed
a significantly higher cyclic fatigue resistance in all
brands compared with continuous rotation. No differences were found between the 2 reciprocating motions.
(J Endod 2013;39:258–261)
Key Words
Continuous rotation, cyclic fatigue, M-wire, nickel-
titanium, reciprocating motion
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