%0 Journal Article %T Effect of Recycling and Autoclave Sterilization on the Unloading Forces of NiTi Closed-Coil Springs: An In Vitro Study %J Journal of Dentistry %I Shiraz University of Medical Sciences %Z 2345-6485 %A Momeni Danaei, Sh. %A Oshagh, M. %A Khozaei, A. %D 2013 %\ 12/01/2013 %V 14 %N 4 %P 184-190 %! Effect of Recycling and Autoclave Sterilization on the Unloading Forces of NiTi Closed-Coil Springs: An In Vitro Study %R %X Statement of Problem: Clinicians use the NiTi coil springs frequently for its appropriate mechanical properties.Purpose: The aim of this study was to determine the effect of recycling and autoclave sterilization on the unloading forces of NiTi closed coil springs.Materials and Method: Fourteen NiTi closed coil spring with the length of 9mm were selected. Each coil was stretched to a peak extension of 12 mm. A universal testing machine was used to acquire load/deflection curve of the coil springs at 25±2°C. The influence of thermocycling (1000 cycles,5-55°C), autoclaving (134°C, 32PSI, 3min) and mechanical strain (9mm extension) which simulated the oral condition, were considered. Data were statistically analyzed by adopting Repeated Measures MANOVA Paired t-Test.Results: Autoclaving in the 1, 4, 6 steps increased the force levels of coil springs about 2-5gf (p< 0.01). Thermocycling reduced their force levels about 4-6gf. Prolonged strain at 3, 5 steps decreased the magnitude of forces levels about 3-4gf.Conclusion: Concerning all the limitations; according to the results of this study; it is possible to recycle Ni-Ti closed-coil springs without significant reduction in their force levels. %U https://dentjods.sums.ac.ir/article_41329_3a053e12b0c88680079c1358308e41fb.pdf