Nickel–titanium alloy was introduced in endodontics 30 years ago when Walia, et al. employed a nickel–titanium arch wire to fabricate a root canal file in 1988.
NiTi endodontic instruments have gained extensive popularity due to their superelasticity and greater torsional resistance than the traditional stainless-steel files.
Therefore, various NiTi endodontic files with different geometric designs have been developed. However, the unexpected separation of NiTi endodontic rotary files during root canal instrumentation still remains a serious drawback in clinical use. Recently, novel kinds of NiTi endodontic files fabricated by proprietary thermomechanical processes such as M-wire files, controlled memory (CM) files, and R-phase wire with different kinematics and design features have been introduced showing improved flexibility and cyclic fatigue resistance compared to the traditional superelastic NiTi files.
The knowledge of the mechanical properties and their association with the metallurgical properties or kinematics of NiTi rotary instruments is helpful to understand the behavior of NiTi instruments in root canals and to make decisions regarding which instruments are appropriate for root canal therapy.
Therefore, this review is intended to summarize the design features and mechanical properties of the traditional superelastic NiTi instruments and contemporary NiTi instruments, and to provide a comparative assessment of rotary and reciprocating motion, discuss the importance of glide path as well as the influence of metallurgical properties on the mechanical properties of NiTi instruments, with a special focus on factors affecting the success of rotary endodontics.
Agarwal S, Nagpal R* and Singh UP Department of Conservative Dentistry and Endodontics, Kothiwal Dental College and Reasearch Centre, India
*Corresponding author: Nagpal R, Department of Conservative Dentistry and Endodontics, Kothiwal Dental College and Research Centre, Moradabad, Uttar Pradesh 244001, India
Received: January 23, 2018; Accepted: February 26, 2018; Published: March 28, 2018
