title: Diffusion of fluorides in human dental enamel in vitro.
abstract: The diffusion of fluoride (F) from sodium fluoride, sodium fluorosilicate, and sodium monoflurophosphate solutions (containing 0.1 per cent F in physiological saline) was studied using a two-chamber diffusion cell separated by enamel membrane. The diffusion coefficient, D in cm2s-1, of F was determined under steady-state conditions over 3 weeks. The D value of F for NaF was significantly higher than for Na2SiF6 and Na2PO3F (p less than 0.001; unpaired t-test). F for acidic Na2SiF6 diffused more rapidly than for Na2PO3F (p less than or equal to 0.001), presumably as HF molecule. Despite the F in the tested solutions being in different forms, i.e. simple ion in NaF or mainly complex ions as in Na2SiF6 and Na2PO3F, the diffusivity of the F in enamel for these compounds was of the same order of magnitude (D = 10(-9)cm2s-1). The findings support the concept that enamel can behave as an ion-selective membrane with certain molecular-sieve effects.
mesh_terms: D003743:Dental Enamel / Q000378:metabolism*; D003745:Dental Enamel Permeability; D004058:Diffusion; D005459:Fluorides / Q000008:administration & dosage / Q000378:metabolism*; D006801:Humans; D010710:Phosphates / Q000378:metabolism; D012824:Silicic Acid / Q000378:metabolism; D012969:Sodium Fluoride / Q000378:metabolism; D013997:Time Factors; D014088:Tooth Permeability
chemical_list: D010710:Phosphates; D012824:Silicic Acid; C012980:fluorophosphate; C004832:hexafluorosilicate; D012969:Sodium Fluoride; D005459:Fluorides