NEW INNOVATION IN ENDODONTIC THERAPY; ELECTRIC DISCHARGE MACHINING
Abstract
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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References
2. Thompson SA. An overview of nickeltitanium alloys used in dentistry. Int Endod J 33, 297–310.
3. Serene TP, Adams JD, Saxena A. Nickel- titanium instruments: Applications in endodontics. St. Louis: Ishiyaku EuroAmerica, Inc.1995
4. Iqbal MK, Kohli MR, Kim JS. A retrospective clinical study of incidence of root canal instrument separation in an endodontics graduate program: a PennEndo database study. J Endod 2006;32, 1048–52.
5. Gambarini G, Plotino G, Grande NM, Al-Sudani D, De Luca M, Testarelli L. Mechanical properties of nickeltitanium rotary instruments produced with a new
manufacturing technique. Int Endod J 2011; 45, 113–28.
6. Shen Y, Zhou H, Zheng Y, Peng B, Haapasalo M. Current challenges and concepts of the thermomechanical treatment of nickel-titanium instruments. J Endod 2013; 39, 163–72.
7. Shen Y, Zhou H, Zheng Y, Campbell L, Peng B, Haapasalo M. Metallurgical characterization of controlled memory wire nickel-titanium rotary instruments. J Endod 2011; 37, 1566–71.
8. Shen Y, Coil JM, Zhou H, Zheng Y, Haapasalo M. HyFlex nickel-titanium rotary instruments after clinical use: metallurgical properties. Int Endod J 46, 720–9.
9. Gutmann JL, Gao Y. Alteration in the inherent metallic and surface properties of nickel-titanium root canal instruments to enhance performance, durability and
safety: a focused review. Int Endod J 2012; 45, 113–28.
10. Ye J, Gao Y. Metallurgical characterization of M-Wire nickeltitanium shape memory alloy used for endodontic rotary instruments during low-cycle fatigue. Int Endod J 2012; 38,105–7.
11. Santos LA, Bahia MG, de Las Casas EB, Buono VT. Comparison of the mechanical behavior between controlled memory and superelastic nickel-titanium files via finite element analysis. J Endod 2013; 39, 1444–7.
12. Daneshmand S, Kahrizi EF, Abedi E, Abdolhosseini MM (2013) Influence of machining parameters on electro discharge machining of NiTi shape memory alloys. Int J of Electrochem Sci, 2013; 8, 3095–104.
13. Jameson, E.C., Description and Development of EDM, Electrical Society of Manufacturing Engineers, Dearbern, Michigan, pp16, 2001.
14. Guo Y, Klink A, Fu C, Snyder J. Machinability and surface integrity of Nitinol shape memory alloy. CIRP Annals-Manufacturing Technology 2013; 62, 83–6.
15. Theisen W, Schuermann A. Electro discharge machining of nickel–titanium shape memory alloys. Materials Science and Engineering 2004; 378, 200–4.
