Background: Thermally activated nickel-titanium wires have been widely used by orthodontists due to more constant forces, generation over longer activation spans, greater resistance to permanent deformation, superelasticity characteristics when cyclically loaded, better spring-back and less hysteresis. Objective: The purpose of this study was to evaluate the influence of clinical use and sterilization process on the Transition Temperature Range (TTR) of thermoset nickel-titanium wires using Differential Scanning Calorimetry (DSC). Methods: Sections from four nickel-titanium wires (0.019 × 0.025-inch) belonging to four different brands were assessed in four different states. Two of the wires were assessed in the “as received” state, one after 60 days of clinical use, and one after 60 days of clinical use and subjected to a sterilization process (autoclaving). The segments of each archwire were tested using DSC at temperatures ranging from −80°C to 150°C at a rate of 10°C/min. Results: All the nickel-titanium memory thermoset wires presented with desirable property for clinical use. The shape memory property was not influenced by clinical use and sterilization process. Conclusion: There was no change in TTR of the nickel-titanium wires after clinical use and sterilization.