Evaluation of Design, Metallurgy, Microhardness and Mechanical Properties of Glide Path Instruments: a Multimethod Approach.

INTRODUCTION This study aims to compare the design, metallurgy, microhardness and mechanical properties of 3 glide path NiTi instruments. METHODS A total of 132 ProGlider, Edge Glide Path and R-Pilot instruments (44 per group) were selected. Design was assessed throughout stereomicroscopy (blades, helical angle, measuring lines, deformation) and scanning electron microscopy (symmetry, cross-section, tip, surface finishing). NiTi ratios were measured by energy-dispersive X-ray spectroscopy and phase transformation temperatures by differential scanning calorimetry. Microhardness and mechanical performance (torsion, bending and buckling resistance tests) were also evaluated. Statistical analyses were performed with Mood's median test with a significance set at 5%. RESULTS Edge Glide Path had the lowest number of blades and R-Pilot the greatest helical angle. All instruments had an almost equiatomic NiTi ratio, while showing different cross-sections and tip geometries. Edge Glide Path had the smoother surface finishing. R-Pilot showed martensitic characteristics at room temperature, while mixed austenite plus R-phase was observed in the others instruments. R-Pilot had higher results on the microhardness (436.8 HVN), maximum torsion (0.9 N.cm) and buckling load (0.7 N) tests (P<.05), while Edge Glide Path had superior angle of rotation (683.5o) and ProGlider was more flexible (144.1 gf) (P<.05). CONCLUSIONS Differences in the instruments' design and phase transformation temperatures accounted for their mechanical behavior. R-Pilot showed the highest torque, buckling and microhardness, while ProGlider instrument was the most flexible.