title: Effect of Ultrasonic Activation of Irrigants on Smear Layer Removal.
abstract: BACKGROUND
  The objective of this study was to evaluate the efficacy of passive ultrasonic irrigation (PUI) with 17% EDTA and 1% NaOCl solutions on smear layer removal.
  
  
  METHODS
  Root canal preparations of 32 human teeth were performed with the ProTaper system. Next, they were longitudinally fractured to permit quantitation of smear layer creation from the cervical, middle, and apical thirds of the roots by using scanning electron microscopy. After reassembling the fractured tooth halves, they were divided into 4 groups according to different final irrigation protocols: group1, EDTA + NaOCl; group 2, EDTA with PUI + NaOCl; group 3, EDTA + NaOCl with PUI; and group 4, EDTA + NaOCl, both with PUI. After irrigation, the tooth halves were separated to permit imaging the same areas by scanning electron microscopy, and a percentage of opened dentinal tubules in irrigated areas as a percent of the total area was obtained. The results were submitted to Kruskal-Wallis, analysis of variance, and Bonferroni tests (α = 0.05).
  
  
  RESULTS
  The cervical third of the samples from all groups showed higher percentage of smear layer removal and open dentinal tubule areas, followed by the middle and apical thirds. Among the irrigation groups, there were statistically significant differences in cervical third between group 2 and group 4 samples, with the highest and lowest percentage of smear layer removal, respectively.
  
  
  CONCLUSIONS
  PUI by using 1% NaOCl and ultrasonic tip placed within 1 mm of the apical foramen did not show higher efficacy in smear layer removal compared with conventional irrigation.
authors.affiliation: Endodontic Division, Department of Dentistry, Federal University of Santa Catarina, Florianópolis, Santa Catarina, Brazil.
authors.forename: Tamer F
authors.initials: TF
authors.lastname: Schmidt
authors.affiliation: Endodontic Division, Department of Dentistry, Federal University of Santa Catarina, Florianópolis, Santa Catarina, Brazil.
authors.forename: Cleonice S
authors.initials: CS
authors.lastname: Teixeira
authors.affiliation: Endodontic Division, Department of Dentistry, Federal University of Santa Catarina, Florianópolis, Santa Catarina, Brazil.
authors.forename: Mara C S
authors.initials: MC
authors.lastname: Felippe
authors.affiliation: Endodontic Division, Department of Dentistry, Federal University of Santa Catarina, Florianópolis, Santa Catarina, Brazil.
authors.forename: Wilson T
authors.initials: WT
authors.lastname: Felippe
authors.affiliation: Department of Oral Biology, College of Dental Medicine, Georgia Regents University, Augusta, Georgia.
authors.forename: David H
authors.initials: DH
authors.lastname: Pashley
authors.affiliation: Endodontic Division, Department of Dentistry, Federal University of Santa Catarina, Florianópolis, Santa Catarina, Brazil. Electronic address: eduardo.bortoluzzi@gmail.com.
authors.forename: Eduardo A
authors.initials: EA
authors.lastname: Bortoluzzi
mesh_terms: D000704:Analysis of Variance; D004492:Edetic Acid / Q000627:therapeutic use; D006801:Humans; D008855:Microscopy, Electron, Scanning; D011897:Random Allocation; D012388:Root Canal Irrigants / Q000627:therapeutic use*; D018915:Root Canal Preparation / Q000379:methods*; D016369:Smear Layer / Q000628:therapy*; D012973:Sodium Hypochlorite / Q000627:therapeutic use; D014070:Tooth / Q000187:drug effects / Q000648:ultrastructure; D014464:Ultrasonic Therapy / Q000379:methods*
chemical_list: D012388:Root Canal Irrigants; D004492:Edetic Acid; D012973:Sodium Hypochlorite
keywords: Irrigation; SEM; passive ultrasonic irrigation; smear layer