Evolution of nickel-titanium instruments: from past to future

Brazilian oral research, 2018

The introduction of automated instrumentation in endodontics represented a major advance in progress for this specialty, with improvements in the quality and predictability of root canal preparation and a significant reduction in procedural errors. In recent years, endodontic instruments have undergone a series of changes brought about by modifications in design, surface treatments, and thermal treatments. In addition, new movements have also been incorporated to offer greater safety and efficiency, optimizing the properties of the NiTi alloy, especially through eccentric rotary motion. An understanding of the mechanical properties of these new NiTi instruments and their effect on the clinical performance of root canal preparation is essential if dental practitioners are to select the instruments that provide optimal clinical outcomes, especially in curved or flattened canals. The objective of this literature review is to present and discuss the characteristics of the NiTi alloys us...

International Endodontic Journal, 2012

Gutmann JL, Gao Y. Alteration in the inherent metallic and surface properties of nickel-titanium root canal instruments to enhance performance, durability and safety: a focused review.

International Journal of Science and Research (IJSR)

World Journal of Dentistry, 2015

In the last decade, nickel-titanium (NiTi) rotary canal instruments have proved to be valuable for root canal therapy because of their exceptional ability to shape root canals with potentially fewer procedural complications. The purpose of this clinical update article is to bring clinicians up to date with the current and popular endodontic rotary NiTi instrument systems. How to cite this article Jain P, Nayan S, Keswani E, Pawar S. Clinical Update on Nickel-Titanium Rotary Instruments. World J Dent 2015;6(2):97-103.

Quintessence International, 2010

The introduction of nickel-titanium (Ni-Ti) to endodontics almost two decades ago 1 has dramatically changed the way root canal preparation is performed, in both general and specialist practices. The perceived most significant advantage lies in the predictability with which a desired shape is achieved. 2 Possibly more important, the use of rotary instruments requires attention to detail, eg, regarding the efficacy of antimicrobial regimes that further contribute to successful endodontic therapy. Then, cases of varying degrees of difficulty can be successfully treated, with excellent long-term outcomes (Fig 1). Not every instrument system is suitable for every clinician, and not all cases lend themselves to rotary preparation, mainly because of varying degrees of experience and complexity. Moreover, rotary instruments may break rather unexpectedly; if they are cleaned and sterilized for reuse, issues of corrosion and persistent contamination may come into play. 3 Therefore, knowledge of both clinical guidelines for and metallurgical properties of Ni-Ti rotary instruments is critical for their successful use. 2,4,5 A recent survey indicated that US-based endodontists are knowledgeable about Ni-Ti instrument usage but are still concerned about issues such as breakage and the quality of the canal shape. 6 Therefore, this review is intended to summarize most recent trends in Ni-Ti technology, instrument design, and usage parameters. This is hoped to provide clinicians a knowledge base for evidence-based practice, thus maximizing the benefits from the selection of Ni-Ti rotary instruments for root canal treatments. NICKEL-TITANIUM METALLURGY AND MANUFACTURING Nickel-titanium alloy, first developed for the US Navy, 7 is in principle highly resistant against corrosion, and, more important, it is superelastic and has a shape memory. The latter two properties stem from an atomic arrangement that is different from conventional alloys such as stainless steel. The atoms in steel can move against each other by a small specific amount before plastic deformation occurs (Fig 2); in contrast, Ni-Ti exists reversibly in two conformations, martensite and austenite, depending on ambient temperature (see Fig 2a) and external tension (see Figs 2b and 2c).

applied sciences, 2023

Abstract: This article aims to explore the importance of multimethod research in assessing the performance of nickel-titanium (NiTi) endodontic instruments. The review highlights the limitations of relying solely on measurements obtained through a narrow set of mechanical tests and acknowledges the challenge of replicating real-world working conditions in controlled laboratory settings. While achieving a perfect simulation may be difficult, the focus should be on developing research strategies that provide a superior understanding of outcomes. The multimethod research, which combines qualitative and quantitative methodologies, offers a promising solution to address this challenge effectively. By integrating nonquantifiable data with quantitative measurements, researchers may overcome the limitations of individual methodologies and gain deeper and more comprehensive insights into instrument performance. This multimethod approach enables a more accurate interpretation of results, enhancing the validity of the methodology. Therefore, conducting a comprehensive analysis of various competencies displayed by NiTi systems is essential for a comprehensive understanding of their characteristics, including cyclic fatigue, torsional and bending resistance, cutting efficiency, microhardness, design analysis, element composition, phase transformation temperatures, shaping ability, and additional methodologies that can address specific inquiries. By combining qualitative and quantitative methodologies in a multimethod approach, researchers can enhance their ability to answer research questions and provide valuable insights for clinical practice.

International Endodontic Journal, 2005

Guelzow A, Stamm O, Martus P, Kielbassa AM. Comparative study of six rotary nickel-titanium systems and hand instrumentation for root canal preparation. International Endodontic Journal, 38, 743-752, 2005. Aim To compare ex vivo various parameters of root canal preparation using a manual technique and six different rotary nickel-titanium (Ni-Ti) instruments (FlexMaster, System GT, HERO 642, K3, ProTaper, and RaCe). Methodology A total of 147 extracted mandibular molars were devided into seven groups (n ¼ 21) with equal mean mesio-buccal root canal curvatures (up to 70°), and embedded in a muffle system. All root canals were prepared to size 30 using a crown-down preparation technique for the rotary nickel-titanium instruments and a standardized preparation (using reamers and Hedströem files) for the manual technique. Length modifications and straightening were determined by standardized radiography and a computer-aided difference measurement for every instrument system. Post-operative cross-sections were evaluated by light-microscopic investigation and photographic documentation. Procedural errors, working time and time for instrumentation were recorded. The data were analysed statistically using the Kruskal-Wallis test and the Mann-Whitney U-test. Results No significant differences were detected between the rotary Ni-Ti instruments for alteration of working length. All Ni-Ti systems maintained the original curvature well, with minor mean degrees of straightening ranging from 0.45°(System GT) to 1.17°( ProTaper). ProTaper had the lowest numbers of irregular post-operative root canal diameters; the results were comparable between the other systems. Instrument fractures occurred with ProTaper in three root canals, whilst preparation with System GT, HERO 642, K3 and the manual technique resulted in one fracture each. Ni-Ti instruments prepared canals more rapidly than the manual technique. The shortest time for instrumentation was achieved with System GT (11.7 s). Conclusions Under the conditions of this ex vivo study all Ni-Ti systems maintained the canal curvature, were associated with few instrument fractures and were more rapid than a standardized manual technique. ProTaper instruments created more regular canal diameters.

Journal of endodontics, 2005

This study assessed the shaping ability of RaCe rotary nickel-titanium instruments in simulated root canals. Forty simulated root canals consisting of four different shapes were prepared with RaCe rotary nickel-titanium instruments in a crowndown approach. Preoperative images were taken at the outset and postoperative images at various stages of preparation including at the conclusion of the shaping procedure. The combined images enabled assessment of aberrations and resin removal at various positions along the canal length. Overall, mean preparation time to size 40, .02 taper was 1.36 min. Thirty-three canals (83%) maintained the working length, three instruments deformed and no zips, perforations, or ledges were created. Under the conditions of this study RaCe rotary nickel-titanium instruments prepared simulated canals rapidly and successfully, with little change in working length and with few aberrations or instrument deformities.

Iranian endodontic journal, 2013

Disinfection and subsequent obturation of the root canal space require adequate mechanical enlargement of the canals. The purpose of this in vitro study was to compare the shaping ability of Mtwo, RaCe and Medin rotary instruments during the preparation of curved root canals. Sixty mesiobuccal root canals of mandibular molars with severe curvatures between 25-35(°) and radius of 4-9 mm were randomly divided into three groups of 20 canals each. Using pre- and post-instrumentation radiographs, straightening of the canal and the apical transportation were determined with AutoCAD software. The data were analyzed using Chi square, analysis of variance, and post-hoc tests and the significance level was set at P<0.05. Mtwo instruments maintained the canal curvature significantly better than Race and Medin instruments (P<0.05). There was significant difference between the rotary instruments for iatrogenic transportation of the major foramen (P>0.05). Under the conditions of this in...

Journal of endodontics, 2010

A finite element model of two nickel-titanium (Ni-Ti) rotary endodontic instruments (ProTaper and SystemGT; Dentsply-Maillefer, Ballaigues, Switzerland) was developed to investigate the mechanical behavior of these devices and to identify the benefits/limitations of different geometries during instrumentation in various root canals. Instrument shape, curved root canal geometry, and Ni-Ti alloy pseudo-elastic behavior were investigated in this study using computational techniques. Two different operating conditions were simulated: (1) the file insertion-removal cycle which resembles the standard working condition and (2) the file subjected to a torque in the counter-clockwise direction, which mimics the auto-reverse movement of the instrument when the tip is locked in the canal wall. The simulations of standard and auto-reverse conditions produced bending and torsion loading conditions in the files, respectively. In the standard situation in which different canal shapes were consider...