Nickel-Titanium Alloys in Endodontics: A Narrative Review

Area of Science:

• Materials Science in Dentistry
• Endodontic Technology
• Biomechanical Engineering

Background:

• Nickel-titanium (NiTi) rotary instruments have revolutionized endodontics, allowing for safer root canal shaping.
• Despite advancements, unexpected instrument fracture remains a significant clinical challenge.

Purpose of the Study:

• To critically analyze the metallurgical evolution and biomechanical performance of NiTi instruments.
• To explore the clinical implications of NiTi alloy properties, heat treatments, and shaping kinematics.
• To emphasize stress management during root canal preparation.

Main Methods:

• A non-systematic narrative review of scientific literature was conducted.
• Analysis included studies on NiTi metallurgy, cyclic fatigue, torsional stress, and corrosion.
• Experimental, metallurgical, and clinical studies were integrated.

Main Results:

• Thermomechanical treatments enhance NiTi flexibility and fatigue resistance by increasing martensitic phase presence.
• Instrument performance depends on alloy metallurgy, design, and operative protocols.
• Surface defects, corrosion, and stress accumulation are critical factors in instrument failure.

Conclusions:

• Clinical safety of NiTi instruments is not solely determined by material properties.
• Root canal shaping is a biomechanical stress management process.
• Integrating metallurgical knowledge with clinical strategies is essential for safer endodontic treatment.