Deformations of the manual endodontic instruments during root canal instrumentation

Abstract

Introduction. Mechanical instrumentation of the complex root canal system is very demanding procedure which requires use of the various manual and rotary instruments. The aim of this study was to assess the frequency and to verify the possible deformation of the working part of endodontic instruments after their multiple clinical use. Material and Methods. New sets of the manual endodontic instruments (reamers, K-files and Hedstroem) used in routine clinical use (44 instruments) and for root canal instrumentation of extracted teeth (44 instruments) were included in the study. Instrumentation was performed by Step-Back technique and constant irrigation with 0.5% NaOCl solution, 10 ml for each root canal. All the instruments were used 10 times and after use sterilized in a dry sterilizer or autoclave. The working parts of deformed instruments were analyzed using optimagnetic print. Results. The results obtained after clinical use showed deformations of the working part of the reamers in 50%, K-files in 43% and Hedstroem in 66.7% of used instruments. After instrumentation the canal of the extracted teeth, deformations were observed in 87.5% of the reamers, in 50% of the K-files and in 62.5% of Hedstroem files. The difference in frequency of the deformations was not statistically significant. On the instruments used for the preparation the canals of the extracted teeth and sterilized in autoclave, malformations were observed in 86.4%, comparing to the instruments sterilized in a dry sterilizer where malformations of the working part were registered in 59.1% of the cases. That difference was statistically significant (χ2=5.250; p=0.072). Conclusion. Multiple use of the manual endodontic instruments in clinical conditions leads to increased frequency of malformations of the working part in all types of manual endodontic instruments

Scanning electron microscopy analysis of conventional and controlled‐memory nickel titanium files before and after multi‐uses in root canals

“…Therefore, instruments were examined before use to determine their intact surface properties, and again after the first, third (roughly after preparing one molar tooth), and sixth (roughly after preparing two molar teeth) use; instruments were evaluated qualitatively in terms of tip deformation, cutting edge deformation, presence of debris, and microcrack formation. In previous studies, dental operation microscopes, stereomicroscopes, micro‐computed tomography, atomic force microscopy, and SEM have been used to evaluate surface deformations in nickel–titanium alloys (Alapati, Brantley, Svec, Powers, & Mitchell, 2003; Nešković et al, 2010; Shen et al, 2015). We used SEM in this study (Alapati et al, 2003; Tripi, Bonaccorso, Tripi, Condorelii, & Rapisarda, 2001) up to ×1,000; SEM is considered an ideal mode of studying surface properties, as it allows repeated imaging, detailed examination, and does not cause any changes in the instruments.…”