Evaluation of the mechanical behaviour of PathFile and ProGlider pathfinding nickel-titanium rotary instruments

AimTo assess and compare the resistance to cyclic fatigue, torsional stress, bending and buckling of ProGlider (PG; Dentsply Maillefer, Ballaigues, Switzerland) instruments with PathFile (PF; Dentsply Maillefer) pathfinding nickel-titanium rotary instruments. MethodologySize 16, .02 taper PG and PF instruments were rotated in simulated canals until failure, and the number of cycles to failure (NCF) was recorded to evaluate their cyclic fatigue resistance. Torsional strength was measured using a torsiometer after fixing rigidly the apical 5mm of the instrument. A scanning electron microscope was used to characterize the topographic features of the fracture surfaces of the instruments. The instruments were evaluated for bending resistance using a cantilever-bending test. The buckling resistance was measured by recording the maximum load required to form a lateral elastic displacement along the file axis using a universal testing machine. Data were statistically analysed using independent t-tests. Statistical significance was set at P<0.05. ResultsProGlider instrument had a significantly higher flexibility, higher resistance to cyclic fatigue and torsional stress than PF instruments (P<0.05). The fractured cross-sectional surfaces revealed typical features of cyclic fatigue and torsional fractures. There was no significant difference in the maximum load needed to buckle the two instruments tested (P=0.082). ConclusionsProGlider NiTi pathfinding instrument manufactured from M-Wire alloy had enhanced mechanical properties, including higher flexibility, higher resistance to cyclic fatigue and torsional stress compared with PathFile instrument made of conventional NiTi alloy.