title: Microhardness of dentin underneath fluoride-releasing adhesive systems subjected to cariogenic challenge and fluoride therapy.
abstract: OBJECTIVE
  The aim of this study was to evaluate the microhardness of dentin subjacent to the bonding interface of composite restorations using fluoride-releasing adhesive systems submitted to pH-cycling regimen associated or not to fluoride therapies.
  
  
  METHODS
  Thirty human third molars were prepared with class V cavities with dentin cervical margins. The adhesive systems One-Up Bond F Plus (OU), Prime&Bond NT (NT), Clearfil Protect Bond (CF), Optibond Solo Plus (OP) and also the controls [-] Single Bond 2 (SB) and [+] Ketac Molar (KM) were used previously to composite resin restorations. The restorations were sectioned into four slabs and submitted to different storage media for 15 days: distilled water, pH-cycling, pH-cycling associated to NaF 0.05% and associated to NaF 1.23%. The Knoop microhardness test was performed in dentin at 50, 100, 150 and 300 microm from the adhesive interface. Data was analyzed by three-way ANOVA and Tukey HSD test (p<0.05).
  
  
  RESULTS
  KM resulted in significantly higher microhardness when compared to all the adhesive systems at 50 microm, with the exception of OU, that was similar to KM when submitted to pH-cycling alone or associated to 1.23% NaF. Microhardness of dentin was significantly higher with all the tested materials, when pH-cycling was associated to NaF 0.05%, at 50 microm and 100 microm depths. OU resulted in similar dentin hardness at all depths and storage media.
  
  
  CONCLUSIONS
  The incorporation of NaF 0.05% fluoride therapy to the cariogenic challenge was capable to recover the original microhardness of dentin at 50 and 100 microm with all the tested materials.
authors.affiliation: Graduation Program in Dentistry, Restorative Dentistry Area, Pontifical Catholic University of Paraná, Curitiba, Paraná, Brazil.
authors.forename: Giovanna A
authors.initials: GA
authors.lastname: Kirsten
authors.forename: Marcos Kenzo
authors.initials: MK
authors.lastname: Takahashi
authors.forename: Rodrigo N
authors.initials: RN
authors.lastname: Rached
authors.forename: Marcelo
authors.initials: M
authors.lastname: Giannini
authors.forename: Evelise M
authors.initials: EM
authors.lastname: Souza
mesh_terms: D002327:Cariostatic Agents / Q000008:administration & dosage* / Q000627:therapeutic use; D003188:Composite Resins / Q000737:chemistry; D003731:Dental Caries / Q000209:etiology*; D003737:Dental Cavity Preparation / Q000145:classification; D003793:Dental Restoration, Permanent / Q000145:classification / Q000379:methods; D003804:Dentin / Q000187:drug effects / Q000473:pathology*; D017220:Dentin-Bonding Agents / Q000737:chemistry*; D005459:Fluorides / Q000008:administration & dosage* / Q000627:therapeutic use; D005899:Glass Ionomer Cements / Q000737:chemistry; D006244:Hardness; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008422:Materials Testing; D008689:Methacrylates / Q000737:chemistry; D011109:Polymethacrylic Acids / Q000737:chemistry; D019279:Resin Cements / Q000737:chemistry; D012969:Sodium Fluoride / Q000627:therapeutic use; D014089:Tooth Remineralization; D014867:Water / Q000737:chemistry
chemical_list: D002327:Cariostatic Agents; C503075:Clearfil Protect Bond; D003188:Composite Resins; D017220:Dentin-Bonding Agents; D005899:Glass Ionomer Cements; D008689:Methacrylates; C446260:One-Up-Bond F; C451600:OptiBond Solo Plus; D011109:Polymethacrylic Acids; C425843:Prime and Bond NT; D019279:Resin Cements; C110712:ketac-molar; D014867:Water; D012969:Sodium Fluoride; D005459:Fluorides