Abstract

Nickel-titanium (NiTi) rotary instruments transformed endodontic shaping by combining flexibility, superelasticity, and improved preservation of canal curvature. The earliest endodontic NiTi file study showed substantially greater flexibility than stainless steel instruments. Subsequent work established that shaping outcomes depend on canal anatomy, instrument design, and clinical technique. During the past three decades, instrument innovation has focused on thermomechanical treatment, cross-sectional refinement, motion control, and surface finishing. Heat-treated alloys and controlled-memory instruments have improved flexibility and cyclic fatigue resistance. However, most commercially available instruments continue to be produced from cylindrical wire blanks using subtractive or near-subtractive manufacturing processes. This review examines metal additive manufacturing as a potential next engineering paradigm for NiTi rotary instrument design. Metal additive manufacturing can build complex metallic structures directly from digital three-dimensional models.

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