NEW INNOVATION IN ENDODONTIC THERAPY; ELECTRIC DISCHARGE MACHINING
Background: Nickel titanium rotary files have become popular because of their superelastic behaviour that makes them the best choice for shaping curved root canals.1 This is mainly because of the superelasticity of NiTi alloy, which provides increased flexibility and allows the instruments to effectively follow the original path of the root canal.2 Despite the advantages related to the superelasticity, fracture of NiTi files due to torsional overloading or flexural fatigue remains a
concern in clinical practice.3,4 Possible strategies to increase efficiency and safety of NiTi rotary files include an improvement in the manufacturing process, or the use of new alloys that provide superior mechanical properties.5 Recently, a series of proprietary thermomechanical processes have been used to optimize the microstructure of NiTi.6,7,8 A new HyFlex CM NiTi rotary files (Coltene Whaledent, Switzerland) with controlled shape memory were introduced. CM wire is obtained by thermally treating the NiTi wires to shift the austenite/ martensite transition temperature at about 50 °C so that a stable martensitic microstructure is allowed at the mouth temperature.9 This imparts to the files a high fatigue resistance and the possibility to be easily bent during use, recovering its original shape by heating above the transformation temperature.10 Recently, patented treatment is involved in the innovative manufacturing of new HyFlex EDM files (Coltene Whaledent, Switzerland). The main feature of these files is that they are manufactured via an electro discharge machining (EDM) process.11-15 The present research evaluated cutting efficacy of a new innovation Hyflex EDM rotary file system manufactured by Electric Discharge Machining.
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