Force magnitude of nickel-titanium orthodontic wires

Objective: The purpose of this study is to evaluate the magnitude of forces released by nickel-titanium (NiTi) orthodontic wires used for leveling and alignment. Materials and Methods: Eleven groups of 0.014” NiTi orthodontic wires of six different brands were tested. A 3342 Instron universal testing machine with a 10 N load cell was used and the ISO 15.841 was followed. Kolmogorov–Smirnov tests were used to verify normality and ANOVA followed by Tukey's tests were used for intergroup comparisons. Results: Abzil conventional, GAC conventional, Morelli heat-activated (HA), Ormco CuNiTi, and Orthometric conventional released load within the optimum range of 50–100 cN. HA wires released lower forces compared to conventional wire of the same brand. Conclusions: Heat-activated Morelli and CuNiTi Ormco presented homogeneous loads within an optimal range.