title: The kinetics of dissolution of tooth enamel--a constant composition study.
abstract: The kinetics of dissolution of powdered bovine enamel and of human enamel, both untreated and extracted with either hypochlorite or chloroform, has been studied using a constant solution composition technique in undersaturated solutions of calcium phosphate (total molar calcium concentration, TCa = 0.3 to 13.1 X 10(-3) mol L-1, total molar phosphate, Tp = 0.18 to 7.9 X 10(-3) mol L-1) at an ionic strength of 0.15 mol L-1, and pH = 4.5. The kinetic equations describing the dissolution reactions suggest a surface dislocation mechanism, and the presence of fluoride ion markedly retarded the reaction. For human enamel, a fluoride level of only 0.5 ppm reduced the rate of dissolution ten-fold. In contrast, the dissolution of hydroxyapatite, HAP, is best interpreted in terms of a polynucleation process.
mesh_terms: D000818:Animals; D002118:Calcium / Q000032:analysis; D002417:Cattle; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D002725:Chloroform; D003743:Dental Enamel / Q000032:analysis* / Q000378:metabolism; D003747:Dental Enamel Solubility / Q000187:drug effects; D017886:Durapatite; D005459:Fluorides / Q000494:pharmacology; D006801:Humans; D006863:Hydrogen-Ion Concentration; D006882:Hydroxyapatites / Q000032:analysis; D006997:Hypochlorous Acid; D007700:Kinetics; D010710:Phosphates / Q000032:analysis
chemical_list: D006882:Hydroxyapatites; D010710:Phosphates; D006997:Hypochlorous Acid; D002725:Chloroform; D017886:Durapatite; D005459:Fluorides; D002118:Calcium