title: The caries-reducing benefit of fluoride-release from dental restorative materials continues after fluoride-release has ended.
abstract: OBJECTIVE
  This study tested the hypothesis that the benefit of fluoride-releasing restorative materials continues even after their reserve of fluoride has been depleted.
  
  
  METHODS
  Pits in perspex blocks simulating cavities were filled with either a fluoride-releasing or a non-fluoride-releasing restorative material and a dentin single-section was placed 1 mm from the edge of the filled pit. These combinations were exposed to an acid gel system. Each demineralized dentin section was separated from the adjacent material and immersed in fresh demineralizing solutions. Transversal microradiographs were taken following the two experimental periods. This study defined ΔΔZ as the increase of integrated mineral loss (ΔZ) during the second acid attack.
  
  
  RESULTS
  The first acid attack substantially demineralized the near-surface region (depth < 40 μm) in all samples. The second acid attack, however, did not cause further demineralization in this near-surface region. Instead, it demineralized dentin deeper than 40-60 μm. The ΔΔZ of the material that did not release fluoride was significantly greater than that of fluoride-releasing materials. Negative correlations were found between ΔΔZ and the mineral volume% of the near-surface region and lesion body of the initial lesions. These results indicate that the dentin mineral in the near-surface region is chemically altered to become acid-resistant fluorapatite. In addition, lesion progression during the second period of demineralization, which was fluoride-free, may have been affected for the materials that have high mineral content of the surface layer and lesion body.
  
  
  CONCLUSIONS
  It is concluded that dentin surrounding fluoride-releasing materials is protected against demineralization even after the fluoride release has diminished.
authors.affiliation: Division of Restorative Dentistry, Department of Oral Medicine, Kanagawa Dental College, Yokosuka, Japan.
authors.forename: Toru
authors.initials: T
authors.lastname: Shiiya
authors.forename: Yoshiharu
authors.initials: Y
authors.lastname: Mukai
authors.forename: Jacob M
authors.initials: JM
authors.lastname: Ten Cate
authors.forename: Toshio
authors.initials: T
authors.lastname: Teranaka
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D017438:Bisphenol A-Glycidyl Methacrylate; D002327:Cariostatic Agents / Q000008:administration & dosage*; D002417:Cattle; D003188:Composite Resins / Q000737:chemistry*; D003731:Dental Caries / Q000517:prevention & control*; D003793:Dental Restoration, Permanent / Q000379:methods*; D003804:Dentin / Q000737:chemistry / Q000000981:diagnostic imaging / Q000378:metabolism; D017886:Durapatite / Q000378:metabolism; D005459:Fluorides / Q000008:administration & dosage*; D005899:Glass Ionomer Cements / Q000737:chemistry*; D008852:Microradiography; D018709:Statistics, Nonparametric
chemical_list: C470433:Beautifil composite resin; D002327:Cariostatic Agents; D003188:Composite Resins; D005899:Glass Ionomer Cements; C083468:Lite-fil CR; C483424:Unifil S; D017438:Bisphenol A-Glycidyl Methacrylate; D017886:Durapatite; D005459:Fluorides