title: Comparison of the effect of four decalcifying agents combined with 60°C 3% sodium hypochlorite on smear layer removal.
abstract: BACKGROUND
  The objective of this study was to compare the efficacy on smear layer removal of 4 decalcifying agents: 17% ethylenediaminetetraacetic acid (EDTA), 20% citric acid, BioPure MTAD, and SmearClear.
  
  
  METHODS
  Forty-five single-rooted human teeth were used and prepared up to ProTaper F3. After each instrumentation, 1 mL of 3% NaOCl at 60°C was irrigated for 1 minute. All the samples were randomly divided into 5 groups according to the final irrigants: 17% EDTA, 20% citric acid, BioPure MTAD, SmearClear, and 3% NaOCl (control). The smear layer removal of all groups at the apical, middle, and coronal thirds was observed under the thermal field emission scanning electron microscope.
  
  
  RESULTS
  The EDTA group was significantly more effective than the SmearClear and MTAD groups (P < .05). The efficacy of all three thirds in the EDTA, MTAD, and SmearClear groups can be arranged as coronal, middle, and apical thirds (P < .05) from excellent to poor. However, in the citric acid group, the coronal two thirds were significantly better than the apical third (P < .05), and there was no statistical significance between the coronal and middle thirds (P > .05).
  
  
  CONCLUSIONS
  The 4 decalcifying agents could effectively, but not completely, remove the smear layer, especially in the apical third. The efficacy of 17% EDTA was better than that of MTAD and SmearClear.
authors.affiliation: Department of Endodontics, School of Stomatology, Tianjin Medical University, Tianjin, China.
authors.forename: Ligeng
authors.initials: L
authors.lastname: Wu
authors.forename: Ying
authors.initials: Y
authors.lastname: Mu
authors.forename: Xiuli
authors.initials: X
authors.lastname: Deng
authors.forename: Shasha
authors.initials: S
authors.lastname: Zhang
authors.forename: Dongyan
authors.initials: D
authors.lastname: Zhou
mesh_terms: D019343:Citric Acid / Q000494:pharmacology; D003786:Dental Pulp Cavity / Q000187:drug effects / Q000648:ultrastructure; D003804:Dentin / Q000187:drug effects* / Q000648:ultrastructure; D004311:Double-Blind Method; D004318:Doxycycline / Q000494:pharmacology; D004492:Edetic Acid / Q000494:pharmacology; D006801:Humans; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D011136:Polysorbates / Q000494:pharmacology; D012388:Root Canal Irrigants / Q000494:pharmacology*; D018915:Root Canal Preparation / Q000295:instrumentation; D016369:Smear Layer; D012973:Sodium Hypochlorite / Q000494:pharmacology*; D019227:Tooth Apex / Q000187:drug effects / Q000648:ultrastructure
chemical_list: C475043:MTAD (intracanal irrigant); D011136:Polysorbates; D012388:Root Canal Irrigants; C521331:Smear Clear; D019343:Citric Acid; D004492:Edetic Acid; D012973:Sodium Hypochlorite; D004318:Doxycycline