Evaluation of surface characteristics of new rotary nickel-titanium instruments - SEM-EDS analysis

Abstract

Introduction. Modern endodontic procedure implies the use of rotary Ni-Ti instruments during chemomechanical treatment of root canals. The aim of this study is to analyze the surfaces of new (unused) rotary endodontic instruments using the SEM-EDS method and determine how frequently manufacture defects or impurities appear on their working surfaces. Material and method. Five new different sets of rotary endodontic Ni-Ti instruments were included in this study: K3, Mtwo, ProTaper Universal, HyFlex and BioRaCe. The working part of endodontic instrument was analyzed using SEMEDS method (magnifications ?150 to ?2000), which determined the morphological characteristics of the instrument surface and chemical composition of the found impurities. Statistical analysis was performed using the Fisher?s test (p < 0.05). Results. The results of SEM-EDS analysis showed that there is no new instrument without defects on its surface. The most common defects were observed in K3 (27.43%) and ProTaper Universal group (27.21%) and the least were in BioRaCe instruments (7.67%). The most common type of defect in tested instruments was fretting. In addition, the presence of debris and metal strips was found on all instruments, while corrosion of the working part was observed only in K3, ProTaper Universal and Mtwo systems in a small percentage. Conclusion. Based on the results of this research, it can be concluded that manufacturing defects were noticed in all examined instruments. The most common defect is pitting. Impurities such as debris and metal strips have also been registered. No organic debris was observed on electropolished surface of BioRaCe instruments, but a small percentage of other types of defects were registered.

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

“…Medojevic et al demonstrated that clean endodontic instruments represent solely presence of nickel and titanium (in ratio of 55.7:44.3%), while impurities on the files' working surfaces were associated with variety of elements [12]. In present study such elements as C, O and some other minor traces were found even at the areas of working surfaces, which did not present any visual signs of impurities.…”

“…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].…”

“…Even though SEM-EDS approach allows to provide elements content analysis of endodontic files' surface, only limited amount of studies have been focused on such specific aspect [7,[12][13][14]. Previously it was demonstrated that presence of carbon and oxygen within rotary instrument may affect its' structural integrity and rigidity thus influencing its' performance, but till now no clear conclusions have been made regarding the impact of different chemical elements accumulation on the functional prognosis of Ni-Ti instruments [15].…”