Perfection of unused Ni-Ti endodontic files, myth or reality? A scanning electron microscope (SEM) study

Abstract

Endodontic rotary files have been developed to improve the quality of root canal preparation. However, such instruments have a risk of separation. In most cases, the files are not checked for quality before use. Instead, they are often removed from the packages, sterilized and used without being examined for the presence of imperfections or debris. Practitioners were always to be blamed of such mishaps, but recently there has been some investigations claiming that these files are not flawless and far from perfection. A sample of 50 files from 5 companies were analyzed under scanning electron microscope (SEM) with 100× magnification and given to 3 blinded endodontic observers to investigate the presence of manufacturing defects. The products of these companies were: Protaper, K3fx, Easy Race, Wave One and Twisted File. All files from each company presented all the 6 categories of defects. Each file presented at least two types of defects. Significant variation was found between companies and defects (p value = 0.03). This study showed that all the brands that had been examined had manufacturing defects in addition to imperfection in packing conditions; however, the electropolished instruments had significantly less imperfection, particularly in term of grooves and scratches.

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

“…Mechanism of such consequences are still not argumented with sufficient evidences and requires more detailed and targeted researches. Some studies reported that amount of surface impurities may be associated with prevalence of surface defects presented in various forms over working part of endodontic files [6,11,13,15]. Combination of both surface defects and surface impurities may affect file's condition in significant manner during its clinical usage and potentially compromise its functional prognosis over repetitive mode of action.…”

“…Scanning electron microscopy (SEM) combined with energy dispersive spectrometry (EDS) have been widely used as non-destructive methods in number of *Address correspondence to this author at the National Healthcare University of Ukraine, All-Ukrainian Association of Endodontists, Kyiv, Ukraine; E-mail: bban@i.ua studies provided for the assessment of endodontic files' surface [6,7,9]. Based on the obtained outcomes it was concluded that even new endodontic instruments may demonstrate various surface defects, most of which were related with the specific process of their manufacturing and packaging [6,[11][12][13][14]. On the other hand SEM-EDS approach also helped to revealed that counterfeit endodontic rotary instruments characterized with increased number of different surface defects, while also with prominent SEM-differences compared to original design of the file [7].…”