title: Analysis of permeability and morphology of root canal dentin after Er,Cr:YSGG laser irradiation.
abstract: OBJECTIVE
  The aim of this study was to evaluate the morphology and permeability of root canal walls irradiated with Er,Cr:YSGG laser after conventional endodontic treatment.
  
  
  BACKGROUND
  Laser irradiation can be used for dentinal tubule exposure, smear layer removal, and disinfection. Another potential, interesting application is as an adjunct to endodontic treatment, especially in the intracanal medication phase.
  
  
  METHODS
  Fifty-two single-rooted teeth had their crowns sectioned at the cementoenamel junction and were randomly divided into four groups (n = 13): G1: conventional preparation (CP) + irrigation with EDTA-T + rhodamine B dye solution associated with NDP (dexamethasone phosphate, paramonochlorophenol, polyethylenoglycol) (Rhod-NDP); G2: CP + EDTA-T + Er,Cr:YSGG laser irradiation 0.75 W + Rhod-NDP; G3: CP + EDTA-T + Er,Cr:YSGG 1.5 W + Rhod-NDP; G4: CP + EDTA-T + Er,Cr:YSGG 2.5 W + Rhod-NDP. For the permeability analysis (n = 9), teeth were transversely cut and two slices of each third were selected. The images were analyzed by ImageLab software (Softium Informática Ltda., São Paulo, SP, Brazil). Additional samples (n = 4) were examined by scanning electron microscopy.
  
  
  RESULTS
  Data were analyzed statistically using the Kruskal-Wallis and Student-Newman-Keuls tests for the following areas: apical third (H = 23.4651): G1 (14.25)(a), G2 (17.66)(ab), G3 (26.50)(b), G4 (39.58)(c); medium (H = 23.1611): G1 (14.16)(a), G2 (16.66)(ab), G3 (28.83)(b), G4 (38.33)(b); and cervical (H = 32.4810): G1 (9.66)(a), G2 (20. 00)(ab), G3 (27.00)(b), G4 (41.33)(c), (p < 0.01). Despite the irregular aspect of laser irradiation along the canal walls, the parameters of 1.5 W and 2.5 W allowed morphologic modifications that increased dentinal permeability.
  
  
  CONCLUSIONS
  Irradiation with Er,Cr:YSGG laser could be effective in endodontic treatment for increasing dentinal permeability.
authors.affiliation: Department of Restorative Dentistry, School of Dentistry, University of São Paulo, São Paulo, Brazil.
authors.forename: Anna Cristina Biella
authors.initials: AC
authors.lastname: Silva
authors.forename: Camila
authors.initials: C
authors.lastname: Guglielmi
authors.forename: Daiane Thais
authors.initials: DT
authors.lastname: Meneguzzo
authors.forename: Ana Cecília Corrêa
authors.initials: AC
authors.lastname: Aranha
authors.forename: Antônio Carlos
authors.initials: AC
authors.lastname: Bombana
authors.forename: Carlos
authors.initials: C
authors.lastname: de Paula Eduardo
mesh_terms: D003804:Dentin / Q000528:radiation effects*; D004708:Endodontics / Q000295:instrumentation*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D053844:Lasers, Solid-State; D028022:Low-Level Light Therapy / Q000295:instrumentation*; D008855:Microscopy, Electron, Scanning; D010539:Permeability; D012235:Rhodamines; D013499:Surface Properties
chemical_list: D012235:Rhodamines; C029773:rhodamine B