Abstract
Knowledge and thorough understanding of the characteristics of endodontic nickel–titanium (NiTi) files is paramount for dentists performing root canal treatments to patients. Understanding the behavior of the NiTi files guides the clinicians in choosing the correct instruments for different clinical and anatomical situations. This review focuses on the metallurgical properties of endodontic NiTi files, with a special emphasis on recent developments and improvements in metallurgy and the effects of heat treatment and surface treatment. In this study, the impact that such developments have on the properties of endodontic NiTi files is discussed.
Highlights
Since Walia and colleagues first introduced nickel–titanium (NiTi) instruments in the late 1980s, NiTi instruments have revolutionized the root canal instrumentation by reducing the majority of iatrogenic instrumentation issues commonly associated with stainless steel files such as zipping, ledges, transportation, and perforation [1, 2].The first NiTi rotary instruments were marketed in the 1990s [3]
The changes in transformation behavior as a result of heat treatment have been found to affect the mechanical characteristics, enhancing clinical performance compared with files of similar design and size made from conventional NiTi alloy
Heat-treated and controlled memory (CM) NiTi instruments are frequently employed by clinicians for endodontic treatment nowadays
Summary
Since Walia and colleagues first introduced nickel–titanium (NiTi) instruments in the late 1980s, NiTi instruments have revolutionized the root canal instrumentation by reducing the majority of iatrogenic instrumentation issues commonly associated with stainless steel files such as zipping, ledges, transportation, and perforation [1, 2]. A conventional NiTi instrument, in an austenitic state at body temperature, exhibits transformational elasticity or the capacity to return to its original shape after being distorted. When external stress such as torsional stress or file friction against canal walls is applied, the stress-induced martensitic transformation occurs, resulting in more resilient materials with a higher ultimate tensile strength [23]. Because the stressinduced martensitic state is not stable at room temperature, once the stress is relieved, the deformed NiTi alloy immediately reverts to the austenite phase. Deformation via martensite reorientation can be observed at temperatures below As, the starting temperature which is important for the reverse transformation of martensite upon heating and is completed at Af [19]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
