title: Micromorphological analysis of dentinal structure after irradiation with Nd:YAG laser and immersion in acidic beverages.
abstract: OBJECTIVE
  The purpose of this study was to analyze dentinal surfaces that were exposed to acidic beverages, then treated with Nd:YAG laser and afterwards exposed to acidic beverages again.
  
  
  BACKGROUND
  Dentin hypersensitivity can result from surface erosion caused by acidic beverages, which exposes and enlarges the dentinal tubules. Nd:YAG laser has been used as a treatment option.
  
  
  METHODS
  Sixty-eight dentin samples were prepared and assigned to five groups: G1, control (n = 4); G2, 3-h immersion (n = 16); G3, 3-h immersion + Nd:YAG; G4, 3-h immersion + Nd:YAG + 3-h immersion; and G5, 3-h immersion + Nd:YAG + 6-h immersion. Each group was divided into four subgroups, with different acid beverages: lemon (n = 4); passion fruit (n = 4); cola (n = 4); and wine (n = 4). Irradiation with the Nd:YAG was in contact mode, focused and perpendicular through a quartz fiber of 300 microm of diameter in scanning movements for 60 sec with a 10-sec interval and the paramenters 0.6 W, 10 Hz, 60 mJ, and 85 mJ/cm(2). Each subgroup was examined by scanning electron microscope.
  
  
  RESULTS
  All the acidic beverages contributed to exposure and increased diameter of the dentinal tubules.
  
  
  CONCLUSIONS
  Irradiation with Nd:YAG laser produced obliteration of and reduction in the number of dentinal tubules, thus modifying the original structure.
authors.affiliation: Department of Restorative Dentistry, School of Dentistry, University of São Paulo, São Paulo, Brazil.
authors.forename: Fláviaviegas
authors.initials: F
authors.lastname: Naylor
authors.forename: Ana Cecilia Corrêa
authors.initials: AC
authors.lastname: Aranha
authors.forename: Carlos De Paula
authors.initials: Cde P
authors.lastname: Eduardo
authors.forename: Victor E
authors.initials: VE
authors.lastname: Arana-Chavez
authors.forename: Maria Angela Pita
authors.initials: MA
authors.lastname: Sobral
mesh_terms: D000328:Adult; D001628:Beverages; D003804:Dentin / Q000648:ultrastructure*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007101:Immersion; D007834:Lasers