Mechanical Properties of Various Heat-treated Nickel-titanium Rotary Instruments
| Autor: | Sang Won Kwak, Hye-Jin Goo, Jung-Hong Ha, Eugenio Pedullà, Hyeon-Cheol Kim |
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| Rok vydání: | 2017 |
| Předmět: |
Cyclic stress
Toughness Materials science Hot Temperature Scanning electron microscope 02 engineering and technology Bending stiffness CM-wire cyclic fatigue electro discharge machining NiTi rotary file torsional fracture resistance Dentistry (all) Curvature Endodontics 03 medical and health sciences 0302 clinical medicine Hardness Nickel Tensile Strength Composite material General Dentistry Titanium 030206 dentistry Radius 021001 nanoscience & nanotechnology Nickel titanium Fracture (geology) Equipment Failure 0210 nano-technology |
| Zdroj: | Journal of endodontics. 43(11) |
| ISSN: | 1878-3554 |
| Popis: | The purpose of this study was to compare the bending stiffness, cyclic fatigue, and torsional fracture resistances of heat-treated and conventional nickel-titanium rotary instruments.V-Taper 2 (VT2; #25/.08), V-Taper 2H (V2H; #25/.06), Hyflex CM (HCM; #25/.06), HyFlex EDM (HDM; #25/variable taper), and ProTaper Next X2 (PTN; #25/variable taper) were tested. The bending stiffness was measured with the customized device (AEndoS), and the files (n = 15) were fixed at 3 mm from the tip and bent at 45° with respect to their long axis. Cyclic fatigue resistance was tested by pecking and rotating instruments (n = 15) in artificial canal with a 7.8-mm radius and 35° angle of curvature until fracture. The ultimate torsional strength and toughness were estimated by using AEndoS. The file tip of 5 mm was fixed between resin blocks and driven clockwise at 20 rpm until fracture. The results were analyzed by using one-way analysis of variance and Duncan post hoc comparison. The fracture surfaces and longitudinal aspect of each group were examined under the scanning electron microscope.CM-wire instruments had lower bending stiffness than others. HDM showed the highest cyclic fatigue resistance, followed by VTH and HCM (P .05). VT2 showed the highest ultimate strength, followed by HDM, VTH-PTN, and HCM. HDM and VT2 showed significantly higher toughness than VTH, HCM, and PTN (P .05). Scanning electron microscope analysis showed typical fractographic features of cyclic fatigue and torsional fractures.CM-wire instruments showed higher flexibility and cyclic fatigue resistance than M-wire and conventional nickel-titanium instruments. Large cross-sectional area and conventional nickel-titanium showed high torsional resistance. |
| Databáze: | OpenAIRE |
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