title: Microscopic study of hydroxyapatite dissolution as affected by fluoride ions.
abstract: Fluoride ions play a critical role in preventing tooth decay. We investigated the microscopic effects of fluoride ions on hydroxyapatite (100) surface dissolution using in situ atomic force microscopy. In the presence of 10 mM NaF, individual surface step retraction velocities decreased by about a factor of 5 as compared to NaF-free conditions. Importantly, elongated hexagonal etch pits, which are characteristic of (100) surface dissolution, were no longer observed when NaF was present. The alteration of pit shape is more distinct at a higher NaF concentration (50 mM) where triangular etch pits evolved during dissolution. Furthermore, in a fluoride concentration typical for tap water (10 μM), we observed roughening of individual step lines, resulting in the formation of scalloped morphologies. Morphological changes to individual steps across a wide range of fluoride concentrations suggest that the cariostatic capabilities of fluoride ions originate from their strong interactions with molecular steps.
authors: Department of Bioengineering, University of California, Berkeley, and Physical Biosciences Division, Lawrence Berkeley National Laboratory , Berkeley, California 94720, United States.
authors: Ki-Young
authors: KY
authors: Kwon
authors: Eddie
authors: E
authors: Wang
authors: Michel
authors: M
authors: Nofal
authors: Seung-Wuk
authors: SW
authors: Lee
mesh_terms: D002327:Cariostatic Agents / Q000737:chemistry* / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D017886:Durapatite / Q000737:chemistry*; D005459:Fluorides / Q000737:chemistry* / Q000494:pharmacology*; D006863:Hydrogen-Ion Concentration; D018625:Microscopy, Atomic Force
chemical_list: D002327:Cariostatic Agents; D017886:Durapatite; D005459:Fluorides