Differences in cyclic fatigue resistance at apical and coronal levels of Reciproc and WaveOne new files.

INTRODUCTION Recent improvements in alloys, kinematics, and concepts have been combined to increase the cyclic fatigue resistance of nickel-titanium (NiTi) instruments. The aim of this study was to compare the cyclic fatigue resistance of new M-Wire reciprocating WaveOne (Dentsply Maillefer, Ballaigues, Switzerland) and Reciproc (VDW GmbH, Munich, Germany) files at 2 levels. METHODS Sixty Reciproc and 60 WaveOne new files were fixed to a specifically designed device and tested in tempered steel canals with a 3-mm radius and a 60° angle of curvature. The motor used was programmed as defined by each manufacturer, and the specific reciprocating motion was followed. Thirty files of each brand were tested at 5 mm, and 30 were tested at 13 mm from their tips. The time to failure was registered. Weibull analysis was used to calculate the mean life, beta, and eta parameters. RESULTS The probability of the mean life was higher for Reciproc than WaveOne files at both levels, with the probability of the Reciproc mean life being 62% higher than that of WaveOne at 5 mm from the tip and 100% higher at 13 mm (all statistically significant). The probability of the mean life was higher at 5 mm than at 13 mm in both systems. The results may have been partially conditioned by the different motions that manufacturers propose for each system. CONCLUSIONS Reciproc files were more resistant to cyclic fatigue than WaveOne files at both distances from the tip. Both systems had greater cyclic fatigue resistance at 5 mm than at 13 mm from the tip.