SEM analysis of defects and wear on Ni–Ti rotary instruments

Abstract

SEM analysis of endodontic instruments from a Ni-Ti rotary system was assessed, before and after using them, considering their defects and deformations. Twenty Twisted File®, BioRąCe®, Mtwo®, and EndoWave® instruments were micrographed at 190× magnification. The files were washed and micrographed again to view alterations as to the presence or absence of irregular edges, grooves, microcavities, and scraping. Simulated root canal preparations were performed using these instruments. The instruments were cleaned and received a microscopic analysis after being used five times. After analysis tests were tested using Fisher's exact test and Kappa to evaluate the concordance among examiners. There was a statistically significant difference with respect to deformations between Twisted File® and other instruments (p < 0.05). There was no statistically significant difference in strains between the other groups (p > 0.05). All Twisted File® instruments showed the same defects; however damage were lower than those found in BioRace® and Mtwo®. The Endowave® did not show the same defects. In accordance with the data we conclude that the presence of defects was higher in Twisted File® instruments as the instruments and BioRace® Mtwo® brand, the defect rate was smaller and Endowave® instruments had no defects. Regarding the presence of wear after five uses among the groups all instruments showed changes in their cutting blades.

Topographic and Chemical Analysis of Reciprocating and Rotary Instruments Surface after Continuous Use

“…As they are manufactured of M-Wire alloy, the clinical reuse of these instruments must be avoided, thereby, diminishing deterioration of the metal alloy, and consequently, the risk of an unexpected fracture of the instrument during use (3,7,9).…”

“…Several studies have reported the accuracy of this method at evaluating changes in the morphological characteristics of metallic materials, such as endodontic instruments (3,7,(13)(14)(15)(16).…”

“…However, manufacturers have recommended their use to a maximum of three or four canals in the same patient. Constant reuse of instruments manufactured in M-Wire leads to wear and deformation, increasing the risk of fracture during preparation (3,7).…”

“…There are few studies that evaluated the topographic and chemical changes that occur on these instrument's surface after their repeated use (3,7). Therefore, the aim of this study was to evaluate the changes in surface characteristics and chemical composition of NiTi alloy of reciprocating and rotary instruments before and after continuous use.…”

Comparison of the Effectiveness of Different Techniques for Supportive Removal of Root Canal Filling Material

“…As shown in previous studies (27,28), cutting activities are reduced, and the instruments are more vulnerable to breakage. Thus, in the present study, the DR1 file was used in three samples and DR2 was used in one sample and then discarded, in accordance with the manufacturer's recommendations (29).…”