Methods for manufacturing an endodontic instrument or device, such as an endodontic file for use in performing root canal therapy on a tooth, are disclosed. The method may include the steps of: (a) providing a wire or wire blank comprising a nickel titanium alloy that has been heat-treated at a heat-treat temperature and has an angle greater than 5 degrees of permanent deformation after torque at 45 degrees of flexion tested in accordance with ISO Standard 3630 Part 1: General requirements and test methods and (b) removing material from the wire or wire blank to form an endodontic instrument or device. The method may include the steps of: (a) providing a wire or wire blank comprising a nickel titanium alloy at a first temperature; and (b) removing material from the wire or wire blank at a second temperature above the first temperature to form an endodontic instrument or device.