Isfahan University of Medical SciencesDental Research Journal1735-33273220080120Force Characteristics of Nickel Titanium Closed Coil Springs (3M, GAC, RMO)7070Sh.Alavi. drj@dnt.mui.ac.irM.Yaghchie20101106Introduction The aim of this study was to compare the characteristics of deflection load of three kinds of nickel titanium closed coil springs. Methods and Materials This research was an experimental study. Research sample contains three kinds of NiTi closed coiled springs (heavy, medium, light) from GAC, 3M, and RMO factories. 10 springs with 9 mm length for each group (totally 90 springs) were subjected to tensile test. They were pulled to 12 mm extension by Dartec machine and then were released. Our variables were maximum force at 12 mm extension, force at the start of the plateau, deflection at the start of plateau, mean force of plateau, plateau slope, force at the end of plateau, deflection at the end of plateau. For tensile test, we used DARTEC universal machine. The data were analyzed by ANOVA and Duncan tests. Results In comparision among identical coils from different factories, the deflection at the end of plateau hadn’t significant difference (P=0.107) but the other parameters had significant differences (P