A dental tool or instrument having a shank located adjacent a first end thereof and a working area located adjacent an opposite second end. At least one elongate cut is formed along the working area and a memorized shape, having at least one protrusion, is formed in the working area. The dental tool or instrument is manufactured from a nitinol wire which initially has a transition temperature that is below room temperature, while the dental tool or instrument, following manufacture, has a final transition temperature of about 90.5±4 degrees Fahrenheit (i.e., 32.5±3 degrees Celsius). When the dental tool or instrument is at a temperature below its final transition temperature, the dental tool instrument is moldable to facilitate insertion into a root canal, but as soon as the dental tool or instrument is at or above the final transition temperature, the dental tool instrument automatically adopts the memorized shape.