title: In Vitro Evaluation of Dentin Hydraulic Conductance After 980 nm Diode Laser Irradiation.
abstract: BACKGROUND
  Dentin hypersensitivity treatments are based on the physical obliteration of the dentinal tubules to reduce hydraulic conductance. The aim of the present study is to evaluate the hydraulic conductance of bovine root dentin after irradiation with a 980-nm diode laser, with or without associated fluoride varnish.
  
  
  METHODS
  Sixty bovine root dentin specimens were divided into six groups (n = 10 in each group): G1, G3, and G5 (0.5 W, 0.7 W, and 1 W diode laser, respectively); G2, G4, and G6 (fluoride varnish application + 0.5 W, 0.7 W, and 1 W diode laser, respectively). The dentin hydraulic conductance was evaluated at four time periods with a fluxmeter: 1) with smear layer, 2) after 37% phosphoric acid etching, 3) after the treatments, and 4) after 6% citric acid challenge. After the dentinal fluid flow measurements, specimens were also evaluated for mineral composition using energy dispersive X-ray spectroscopy (EDS).
  
  
  RESULTS
  Analysis demonstrated a better result with increased irradiation power (P < 0.001), especially if the diode laser irradiation was associated with the application of fluoride varnish (P < 0.001), ensuring a greater reduction in permeability. Considering the groups treated only with laser irradiation, the 1 W group was superior when compared with the 0.5 W and 0.7 W irradiated groups immediately after treatment (P < 0.001). After citric acid testing, all groups showed similar results, except when comparing the 1 W groups with the 0.5 W groups (P = 0.04). EDS results of the irradiated groups showed an increase in the proportion of calcium and phosphorus ions, which demonstrates a superficial composition modification after laser treatments.
  
  
  CONCLUSIONS
  Laser irradiation of exposed dentin promoted significant reduction in the dentin hydraulic conductance, mainly with higher energy densities and association with fluoride varnish.
authors.affiliation: Department of Operative Dentistry, Endodontics and Dental Materials, Bauru School of Dentistry, University of São Paulo, São Paulo, Brazil.
authors.forename: Fabio A P
authors.initials: FA
authors.lastname: Rizzante
authors.affiliation: Department of Operative Dentistry, Endodontics and Dental Materials, Bauru School of Dentistry, University of São Paulo, São Paulo, Brazil.
authors.forename: Rafael M
authors.initials: RM
authors.lastname: Maenosono
authors.affiliation: Department of Operative Dentistry, Endodontics and Dental Materials, Bauru School of Dentistry, University of São Paulo, São Paulo, Brazil.
authors.forename: Marco A H
authors.initials: MA
authors.lastname: Duarte
authors.affiliation: Department of Operative Dentistry, Endodontics and Dental Materials, Bauru School of Dentistry, University of São Paulo, São Paulo, Brazil.
authors.forename: Adilson Y
authors.initials: AY
authors.lastname: Furuse
authors.affiliation: Department of Restorative Dentistry, Ribeirão Preto School of Dentistry, University of São Paulo.
authors.forename: Regina G
authors.initials: RG
authors.lastname: Palma-Dibb
authors.affiliation: Department of Operative Dentistry, Endodontics and Dental Materials, Bauru School of Dentistry, University of São Paulo, São Paulo, Brazil.
authors.forename: Sérgio K
authors.initials: SK
authors.lastname: Ishikiriama
mesh_terms: D000818:Animals; D002417:Cattle; D003804:Dentin; D003807:Dentin Sensitivity; D054023:Lasers, Semiconductor / Q000627:therapeutic use; D008855:Microscopy, Electron, Scanning; D016369:Smear Layer; D013052:Spectrometry, X-Ray Emission
keywords: Dentin permeability; dentin sensitivity; in vitro techniques; lasers; pain; sodium fluoride