title: Physical and chemical characterization of the surface layers formed on dentin following treatment with an experimental anhydrous stannous fluoride dentifrice.
abstract: OBJECTIVE
  To characterize, in vitro, the mode of action of stannous fluoride containing formulations in occluding dentin tubules, by means of high resolution microscopy techniques.
  
  
  METHODS
  Focused ion beam scanning electron microscopy (FIB SEM) was used to site-specifically prepare cross sections for SEM and TEM imaging and analysis of dentin samples treated with either a stannous fluoride dispersion in glycerol or an experimental stannous fluoride dentifrice.
  
  
  RESULTS
  An experimental stannous fluoride dentifrice formed a protective layer over the dentin surface and occluded dentin tubules. Additional supporting data derived from a stannous fluoride dispersion in glycerol suggest that stannous fluoride is a key component of this occluding system. Multiple SEM images obtained from sequential FIB cross-sections were reconstructed into 3-dimensional tomograms that showed a formed layer and tubule occlusion. Sections thinned by FIB techniques were observed by transmission electron microscopy (TEM) and related methods and showed that the coating, which was up to 3 microm-thick, consisted of a tin containing precipitate. Chemical analysis by energy dispersive x-ray spectroscopy (EDS) mapping that used scanning TEM (STEM) methods showed interdiffusion of tin up to 200 nm into the dentin structure.
authors.affiliation: GlaxoSmithKline Consumer Healthcare, St Georges Avenue, Weybridge, KT13 ODE United Kingdom. jonathan.s.earl@gsk.com
authors.forename: Jonathan S
authors.initials: JS
authors.lastname: Earl
authors.forename: Richard M
authors.initials: RM
authors.lastname: Langford
mesh_terms: D003802:Dentifrices / Q000737:chemistry / Q000494:pharmacology*; D003804:Dentin / Q000187:drug effects*; D003806:Dentin Permeability; D003807:Dentin Sensitivity / Q000209:etiology / Q000517:prevention & control; D019234:Dentinal Fluid / Q000502:physiology; D004337:Drug Carriers; D005990:Glycerol; D006801:Humans; D008855:Microscopy, Electron, Scanning; D046529:Microscopy, Electron, Transmission; D013499:Surface Properties / Q000187:drug effects; D014002:Tin Fluorides / Q000737:chemistry / Q000494:pharmacology*
chemical_list: D003802:Dentifrices; D004337:Drug Carriers; D014002:Tin Fluorides; D005990:Glycerol