Local Elements Content on Working Surfaces of Five Different New Ni-Ti Rotary Endodontic Files: SEM-EDS Study

Abstract

Objective: To assess diversity of local elements content within working surfaces of five different new Ni-Ti rotary endodontic files.
 Methods: Energy dispersive spectrometry (EDS) for local elements content analysis was held within three specific areas of working surfaces of the files identified over received SEM images: 1) with pronounced visible signs of impurities; 2) with slightly visible signs of impurities; 3) with no visible signs of impurities. EDS procedure was provided with the use of EDS-detector. Local elements content data at the three above-mentioned specific areas of files’ working surfaces was presented in means of weight percent (wt%), normalized to 100%, and was automatically calculated by the SEM-EDS software.
 Results: Expressiveness of visible signs of impurities present over working surfaces of the files demonstrated correlation with nickel (r=-0.62, p < 0.05) and titanium (r=-0.49, p < 0.05) content at analyzed areas, while also with carbon (r=0.57, p < 0.05) and oxygen (r=0.50, p < 0.05) content at analyzed areas. Odds ratio for possibility to register traces of one of the following elements N, Na, Mg, Al, Si, S, Cl, Cr, Fe, Ca at the working surface of endodontic file under condition of present pronounced visible signs of impurities was found to be at the level of OR=12.5 (95% CI: 1.08; 143.44; p=0.04).
 Conclusions: None of the analyzed files was free of impurities over their working surface. Carbon, oxygen, nickel, and titanium were the most prevalent elements observed along working surfaces of five new different endodontic files, while some instruments were characterized with the presence of tungsten, silicon, aurum, iron, chromium, magnesium and nitrogen, maximum level of which at selected areas with pronounced visible signs of impurities outreach 10% weight percent values.