title: Effect of application time of APF and NaF gels on microhardness and fluoride uptake of in vitro enamel caries.
abstract: OBJECTIVE
  To evaluate the effect of time of fluoride application gel, acidulated or neutral, on in vitro enamel resistance to demineralization and fluoride uptake.
  
  
  METHODS
  One hundred and ninety-two human enamel blocks were used in this study and 144 were treated with fluoride gel, acidulated or neutral, for 1 or 4 minutes. Ninety-six blocks treated with fluoride and 24 control blocks were submitted to a high cariogenic challenge. After the pH-cycling, enamel demineralization was assessed by surface and cross-sectional microhardness. Fluoride in the enamel blocks was also determined after removing an enamel layer by etching acid.
  
  
  RESULTS
  Acidulated fluoride gel formed more fluoride in enamel than neutral gel (P<0.05), and it was also more efficient in reducing the demineralization of the enamel blocks submitted to a cariogenic challenge than the neutral one (P<0.05). It was found that the time of application was significant in terms of fluoride uptake, but it did not render the enamel more resistant to demineralization.
authors.affiliation: Department of Pediatric Dentistry, Faculty of Dentistry of Araçatuba, UNESP, São Paulo, Brazil.
authors.forename: Alberto Carlos Botazzo
authors.initials: AC
authors.lastname: Delbem
authors.forename: Jaime A
authors.initials: JA
authors.lastname: Cury
mesh_terms: D000149:Acidulated Phosphate Fluoride / Q000008:administration & dosage*; D000704:Analysis of Variance; D002327:Cariostatic Agents / Q000008:administration & dosage* / Q000493:pharmacokinetics; D003731:Dental Caries / Q000378:metabolism / Q000473:pathology*; D003733:Dental Caries Susceptibility / Q000187:drug effects; D003743:Dental Enamel / Q000187:drug effects* / Q000378:metabolism / Q000648:ultrastructure; D003747:Dental Enamel Solubility / Q000187:drug effects; D005459:Fluorides / Q000493:pharmacokinetics*; D006244:Hardness; D006801:Humans; D006863:Hydrogen-Ion Concentration; D016555:Matched-Pair Analysis; D012969:Sodium Fluoride / Q000008:administration & dosage*; D013223:Statistics as Topic; D013997:Time Factors; D017001:Tooth Demineralization / Q000503:physiopathology
chemical_list: D002327:Cariostatic Agents; D000149:Acidulated Phosphate Fluoride; D012969:Sodium Fluoride; D005459:Fluorides