Torsion and bending properties of OneShape and WaveOne instruments

The purpose of this study was to compare the torsion and bending properties of OneShape (OS; Micro Mega, Besançon, France) and WaveOne (WO; Dentsply Maillefer, Ballaigues, Switzerland) single-file systems.

The torsional strength of OS size #25, 0.06 taper and WO primary size #25, 0.08 taper was measured by using a torsiometer after fixing the apical 5 mm of the instrument rigidly. A scanning electron microscope was used to characterize the topographic features of the fracture surfaces of broken files. The files were tested for bending resistance by using the cantilever bending test. Data were statistically analyzed using the independent t test. Statistical significance level was set at P < .05.

WO had a significantly higher torsional resistance than OS (P < .001). The average bending resistance as measured by the maximum force (gf) to bend instruments revealed that the WO had a significantly lower resistance to bend than OS (P < .001). Scanning electron microscopic analysis of the fractured cross-sectional surfaces revealed typical features of torsional failure including skewed dimples near the center of the fracture surface and circular abrasion streaks.

The WO single-file system showed higher torsional resistance and flexibility than the OS single-file system. Different cross-sectional geometry and the alloy from which the instrument is manufactured could have significant influence on the torsional resistance and flexibility of the instruments.