Resistance to flexural fatigue of RECIPROC R25 files under continuous rotation and reciprocating movement

Authors: G. Gavini, C. L. Caldeira, E. Akisue, G. Taccio de Miranda Candeiro, D. A.S. Kawakami
Year: 2012
Rubrics: Cyclic fatigue
Keywords: resistance to cyclic fatigue, cyclic fatigue

Introduction The aim of the present work was to evaluate  the resistance to flexural fatigue of Reciproc R25  nickel-titanium files, 25 mm, used in continuous rotation  motion or reciprocation motion, in dynamic assays  device.

Methods Thirty-six Reciproc R25 files were  divided into 2 groups (n = 18) according to kinematics  applied, continuous rotary (group CR) and reciprocation  motion (group RM). The files were submitted to dynamic  assays device moved by an electric engine with 300 rpm  of speed that permitted the reproduction of pecking  motion. The files run on a ring’s groove of temperate  steel, simulating instrumentation of a curved root canal  with 40_ and 5 mm of curvature radius. The fracture of  file was detected by sensor of device, and the time was  marked. The data were analyzed statistically by  Student’s t test, with level of significance of 95%. 

Results The instruments moved by reciprocating movement  reached significantly higher numbers of cycles  before fracture (mean, 1787.78 cycles) when compared  with instruments moved by continuous rotary (mean,  816.39 cycles).

Conclusions The results showed that  the reciprocation motion improves flexural fatigue resistance  in nickel-titanium instrument Reciproc R25 when  compared with continuous rotation movement.  

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