9/9/2023 0 Comments Endodontic rotary file systems![]() ![]() The latter allows NiTi alloy to “memorize” a pre-imposed form and to return to it on heating, as a consequence of the transition from the martensitic crystallographic phase to the austenitic phase. The former is defined as the ability of the alloy to store stress up to 8% without being plastically deformed, remaining in the elastic region of deformation by the creation of a stress-induced phase, called stress-induced martensite (SIM). The widespread use of NiTi rotary instruments, which have almost completely replaced stainless-steel (SS) manual instruments, fundamentally arose from the two most characteristic features of NiTi alloy: superelasticity and the shape memory effect. From that moment, the way of conceiving endodontics changed considerably, although its basic principles have remained the same and could be mostly summarized in three key processes: chemo-mechanically disinfecting the root canal system to achieve a reduction in bacteria as far as possible obtaining a stable root canal filling to entomb residual bacteria and to isolate the endodontic system from the periapical tissues obtaining a stable coronal restoration to avoid secondary infections of the root canal system. ![]() It could be stated that the modern era of endodontics began after the introduction of the nickel–titanium (NiTi) alloy as the material of choice for the manufacturing of endodontic instruments. Few studies were conducted using other tests such as FIB (2 articles), micro-Raman spectroscopy (4 articles), metallographic analysis (7 articles) and Auger electron spectroscopy (2 articles). The most popular metallurgical test was DSC, with 43 related articles, followed by EDS (33 articles), AFM (22 articles) and XRD (21 articles). According to the results, more than 50% of the selected articles were published in one of the two most relevant journals in endodontics: International Endodontic Journal (22.2%) and Journal of Endodontics (29.6%). Considering the inclusion and exclusion criteria, of the 248 articles found, only 81 were included in the narrative review. The search was conducted using the following keywords: “metallurgy”, “differential scanning calorimetry” (DSC), “X-ray diffraction” (XRD), “atomic force microscopy” (AFM), “energy-dispersive X-ray spectroscopy” (EDS), “focused ion beam analysis” (FIB) and “Auger electron spectroscopy” (AES) combined with the term “endodontics” or “NiTi rotary instruments”. ![]() With this purpose, a literature search for articles published between January 2001 and December 2021 was conducted, using the electronic database PubMed to collect all published articles regarding the metallurgical tests used in endodontics for the evaluation of NiTi rotary instruments. Since there are no reviews of the literature on this theme, the aim of this narrative review is to summarize the metallurgical tests used in endodontics, pointing out their functional use and their pros and cons and giving readers a user-friendly guide to serve as an orientation aid in the plethora of metallurgical tests. ![]()
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