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.

Atualmente o uso de instrumentos rotatórios é uma realidade, porém, estes apresentam restos de resíduos na superfície de corte. Sendo assim, o objetivo deste trabalho foi avaliar por meio de microscopia eletrônica de varredura (MEV), a presença de resíduos na superfície de corte de 20 instrumentos rotatórios de NiTi sem uso. Foram divididos em quatro grupos, a saber: Grupo A - TwistedFile® (n=5), Grupo B - BioRaCe® (n=6), Grupo C - Mtwo® (n=4) e Grupo D - EndoWave® (n=5). As pontas dos instrumentos foram microfotografadas com aumento de 190X a partir do diâmetro inicial para verificar a presença de resíduos. Em seguida, os instrumentos passaram por um rigoroso processo de limpeza e novamente microfotografados com o mesmo padrão de aumento, observando-se a ponta do instrumento e a 5mm da ponta do instrumento. Os dados obtidos foram tabulados e submetidos à análise percentual e estatística valendo-se do teste Exato de Fisher e nível de significância de 5%. No que se refere à sujidade ocorreram diferenças estatisticamente significantes entre as limas Mtwo® com os outros instrumentos (p<0,05). Concluiu-se que todos os instrumentos estavam sujos, exceto a marca Mtwo® e que após os procedimentos de limpeza a superfície de corte estava isenta de resíduos.