title: Presence of Metallic Microfragments on Dentinal Walls and Instrument Defects following Root Canal Preparation.
abstract: OBJECTIVE
  To determine the presence of metallic microfragments and their elemental composition in the dentinal walls of root canals following preparation using different endodontic instruments and to assess the active cutting edges of instruments with regard to structural defects.
  
  
  METHODS
  A total of 108 molar teeth were selected and prepared using different endodontic instruments. Teeth were randomly divided into nine groups of 12 teeth each, according to the instruments employed: Manual systems -K-FlexoFile, K-File, and Hedstroem; rotary systems - ProTaper Next, Mtwo, BioRaCe; and reciprocating systems - Reciproc, Unicone, and WaveOne. Both root canals and instruments were assessed using scanning electron microscopy, and the elemental composition of metallic microfragments was determined using energy-dispersive X-ray spectroscopy.
  
  
  RESULTS
  Metallic microfragments were found in the groups prepared with both manual and reciprocating instruments, with no statistically significant differences between groups, thirds, or presence of metallic microfragments (p ≥ 0.05). Moreover, all groups presented structural defects in both new and used instruments; however, rotary instruments (ProTaper Next, Mtwo 702, BioRaCe) were the ones with the lowest number of defects, at statistically significant differences in comparison with other instruments (p < 0.05).
  
  
  CONCLUSIONS
  The presence of metallic microfragments on dentinal walls following root canal preparation was associated with manual and reciprocating instrumentation. Furthermore, rotary instruments were the ones with the lowest number of defects. Considering the outcomes measured in this study, rotary instruments performed better than the other two groups, as they were associated with the lowest number of metallic microfragments and structural defects.
  
  
  CONCLUSIONS
  During root canal preparation, operative procedures may induce changes to the root canal shape, as well as the release of metallic fragments resulting from the action of instruments on dentinal walls. Therefore, it is important to determine, among the different techniques used for this purpose, which ones are least susceptible to this occurrence.
authors.affiliation: Department of Dentistry, Universidade Luterana do Brasil Canoas, Rio Grande do Sul, Brazil.
authors.forename: Caroline
authors.initials: C
authors.lastname: Solda
authors.affiliation: Department of Dentistry, Universidade Luterana do Brasil Canoas, Rio Grande do Sul, Brazil.
authors.forename: Marina C
authors.initials: MC
authors.lastname: Langaro
authors.affiliation: Department of Dentistry, Universidade Luterana do Brasil Canoas, Rio Grande do Sul, Brazil.
authors.forename: Alessandra N
authors.initials: AN
authors.lastname: Machado
authors.affiliation: Department of Endodontics, CEOM and Faculdade Meridional IMED, Passo Fundo, Rio Grande do Sul, Brazil.
authors.forename: José R
authors.initials: JR
authors.lastname: Vanni
authors.affiliation: Department of Endodontics, Universidade Federal de Goiás Goiânia, Brazil.
authors.forename: Daniel
authors.initials: D
authors.lastname: de A Decurcio
authors.affiliation: Department of Endodontics, Universidade Federal de Goiás Goiânia, Brazil.
authors.forename: Julio A
authors.initials: JA
authors.lastname: Silva
authors.affiliation: Department of Endodontics, Universidade Federal de Goiás Goiânia, Brazil.
authors.forename: Carlos
authors.initials: C
authors.lastname: Estrela
authors.affiliation: Department of Endodontics, Universidade Luterana do Brasil Canoas, Rua Voluntários da Pátria, 9, Centro Histórico, Porto Alegre, Rio Grande do Sul Brazil, e-mail: fbarletta@terra.com.br.
authors.forename: Fernando B
authors.initials: FB
authors.lastname: Barletta
mesh_terms: D003804:Dentin / Q000737:chemistry*; D004868:Equipment Failure; D006801:Humans; D008670:Metals / Q000032:analysis*; D008855:Microscopy, Electron, Scanning; D018915:Root Canal Preparation / Q000009:adverse effects* / Q000295:instrumentation; D013052:Spectrometry, X-Ray Emission
chemical_list: D008670:Metals
keywords: Endodontic instruments; Instrument defects; Laboratory research Reciprocating instruments.