title: Efficacy of Er,Cr:YSGG laser in removing smear layer and debris with two different output powers.
abstract: OBJECTIVE
  The purpose of this study was to evaluate the effectiveness of the erbium, chromium: yttrium-scandium-gallium-garnet (Er,Cr:YSGG) laser in removing debris and the smear layer using two different output powers on the apical, middle, and coronal segments of root canal walls.
  
  
  BACKGROUND
  Previous literature has failed to evaluate the exclusive effect of Er,Cr:YSGG laser on the quality of smear layer and debris removal in all three segments of the root canal space.
  
  
  METHODS
  Sixty extracted teeth were included in the study. After instrumentation, samples were divided into three experimental groups and one positive control group with no further treatment. In group 1, a final irrigation was performed using ethylenediaminetetraacetic acid (EDTA) and sodium hypochlorite (NaOCl), sequentially. In group 2, the samples were treated with a 2.78 μm Er,Cr:YSGG laser with an output power of 1.5 W. The same laser was used in group 3, but with an output power of 2.5 W. Scanning electron microscope (SEM) images from the coronal, middle, and apical thirds of the roots were prepared and evaluated for both smear layer and debris removal by three blinded observers.
  
  
  RESULTS
  The results showed no differences between groups 1 and 2 regarding the quality of smear layer removal in all areas. However, the 2.5 W laser failed to remove the smear layer effectively. Regarding debris removal, the EDTA and NaOCl irrigation showed significantly better outcomes (adjusted p<0.05) in all areas.
  
  
  CONCLUSIONS
  This study raises questions about the overall cleaning abilities of Er,Cr:YSGG lasers.
authors.affiliation: 1 Department of Endodontics, School of Dentistry, Tehran University of Medical Sciences , Tehran, Iran .
authors.forename: Behnam
authors.initials: B
authors.lastname: Bolhari
authors.forename: Sara
authors.initials: S
authors.lastname: Ehsani
authors.forename: Ardavan
authors.initials: A
authors.lastname: Etemadi
authors.forename: Mohammad
authors.initials: M
authors.lastname: Shafaq
authors.forename: Ali
authors.initials: A
authors.lastname: Nosrat
mesh_terms: D002857:Chromium; D003786:Dental Pulp Cavity / Q000528:radiation effects*; D004492:Edetic Acid / Q000494:pharmacology; D004871:Erbium; D005708:Gallium; D006801:Humans; D066298:In Vitro Techniques; D053844:Lasers, Solid-State; D008855:Microscopy, Electron, Scanning; D015203:Reproducibility of Results; D012388:Root Canal Irrigants / Q000494:pharmacology; D018915:Root Canal Preparation; D012538:Scandium; D016369:Smear Layer / Q000517:prevention & control*; D015019:Yttrium
chemical_list: D012388:Root Canal Irrigants; D002857:Chromium; D015019:Yttrium; D004871:Erbium; D004492:Edetic Acid; D005708:Gallium; D012538:Scandium