title: Qualitative analysis of the removal of the smear layer in the apical third of curved roots: conventional irrigation versus activation systems.
abstract: BACKGROUND
  The aim of this study was to evaluate the effectiveness of different irrigant agitation techniques on smear layer removal in curved root canals.
  
  
  METHODS
  Mesiobuccal canals of 62 extracted lower molars with a curvature of 33 degrees were used and instrumented up to ProTaper F2. The samples were divided into 3 experimental groups according to the final irrigation: conventional irrigation, ultrasonic irrigation, and sonic irrigation by using the EndoActivator system. The control group was composed of 2 specimens without any final irrigation. In all of the experimental groups, 5 mL of 17% ethylenediaminetetraacetic acid was used for 1 minute, and 5 mL of 2.5% NaOCl was used for 30 seconds. The analysis of the apical region was performed via scanning electron microscopy by 3 examiners. The data were submitted to the Kruskal-Wallis and Dunn tests (P < .05).
  
  
  RESULTS
  The activation systems removed significantly more smear layer than did conventional irrigation.
  
  
  CONCLUSIONS
  Sonic and ultrasonic irrigation resulted in better removal of the smear layer in the apical third of curved root canals than did conventional irrigation.
authors.affiliation: Department of Restorative Dentistry, School of Dentistry, University of São Paulo, São Paulo, São Paulo, Brazil.
authors.forename: Luciana Magrin
authors.initials: LM
authors.lastname: Blank-Gonçalves
authors.forename: Cleber Keiti
authors.initials: CK
authors.lastname: Nabeshima
authors.forename: Guilherme Henrique Rosa
authors.initials: GH
authors.lastname: Martins
authors.forename: Manoel Eduardo de Lima
authors.initials: ME
authors.lastname: Machado
mesh_terms: D003786:Dental Pulp Cavity / Q000033:anatomy & histology*; D006801:Humans; D008963:Molar; D023861:Photography, Dental; D036301:Qualitative Research; D012388:Root Canal Irrigants / Q000008:administration & dosage*; D018915:Root Canal Preparation / Q000379:methods*; D016369:Smear Layer; D013010:Sonication; D018709:Statistics, Nonparametric; D007507:Therapeutic Irrigation / Q000295:instrumentation / Q000379:methods*; D019227:Tooth Apex / Q000648:ultrastructure; D014464:Ultrasonic Therapy; D014732:Vibration
chemical_list: D012388:Root Canal Irrigants