title: Effect of Nd:YAG irradiation and fluoride application on dentine resistance to erosion in vitro.
abstract: OBJECTIVE
  In this paper we evaluated the effect of two fluoridated agents and Nd:YAG irradiation separately and in combination on dentine resistance to erosion.
  
  
  BACKGROUND
  The morphological changes in dentin induced by laser treatment may reduce the progression of erosive lesions. Due to the possibility of a synergistic effect of laser with fluoride, this study was conducted.
  
  
  METHODS
  Eighty bovine dentine samples (4 x 4 mm) were randomly divided into eight groups, according to the following treatments: G1: untreated (control); G2: acidic phosphate fluoride gel (APF 1.23%) for 4 min; G3: fluoride varnish (NaF 2.26%) for 6 h; G4: 0.5 W Nd:YAG laser (250 microsec pulse, 10 Hz, 35 J/cm2, 30 sec); G5: 0.75 W Nd:YAG laser (52.5 J/cm2); G6: 1.0 W Nd:YAG laser (70 J/cm2); G7: APF + 0.75 W Nd:YAG laser; and G8: NaF + 0.75 W Nd:YAG laser. After the treatments, half of each dentine surface was protected with nail varnish. The samples were stored in artificial saliva (30 mL/sample) for 24 h and submitted to four erosive 1-min cycles. Between the erosive attacks, the blocks were maintained in artificial saliva for 59 min. The erosive wear was evaluated by profilometry.
  
  
  RESULTS
  The mean wear (+/-SD, microm) was: G1: 1.20 +/- 0.20; G2: 0.47 +/- 0.06; G3: 0.81 +/- 0.11; G4: 1.47 +/- 0.32; G5: 1.52 +/- 0.24; G6: 1.49 +/- 0.30; G7: 0.49 +/- 0.11; and G8: 1.06 +/- 0.31 (Tukey's test, p< 0.05).
  
  
  CONCLUSIONS
  Laser irradiation was not able to reduce dentine erosion. However, fluoride application was able to increase the dentine's resistance to erosion, and APF showed better results than fluoride varnish.
authors.affiliation: Department of Child and Social Dentistry, School of Dentistry of Araçatuba, São Paulo State University, Araçatuba, Brazil.
authors.forename: Ana Carolina
authors.initials: AC
authors.lastname: Magalhães
authors.forename: Daniela
authors.initials: D
authors.lastname: Rios
authors.forename: Maria Aparecida De Andrade
authors.initials: MA
authors.lastname: Machado
authors.forename: Salete Moura Bonifácio
authors.initials: SM
authors.lastname: Da Silva
authors.forename: Rosane De Fátima Zanirato
authors.initials: Rde F
authors.lastname: Lizarelli
authors.forename: Vanderlei Salvador
authors.initials: VS
authors.lastname: Bagnato
authors.forename: Marília Afonso Rabelo
authors.initials: MA
authors.lastname: Buzalaf
mesh_terms: D000149:Acidulated Phosphate Fluoride / Q000008:administration & dosage*; D000818:Animals; D002417:Cattle; D003804:Dentin / Q000187:drug effects* / Q000528:radiation effects*; D005460:Fluorides, Topical / Q000008:administration & dosage*; D053844:Lasers, Solid-State; D014077:Tooth Erosion / Q000517:prevention & control*
chemical_list: D005460:Fluorides, Topical; D000149:Acidulated Phosphate Fluoride