title: Constant composition dissolution of mixed phases. II. Selective dissolution of calcium phosphates.
abstract: Characterization of the dissolution kinetics of individual synthetic and biological calcium phosphates is of considerable importance since these phases often coexist in biological minerals. The constant composition method has been used to study the dissolution kinetics of a series of synthetic calcium phosphates, brushite (DCPD), beta-tricalcium phosphate (TCP), octacalcium phosphate (OCP), hydroxyapatite (HAP), and carbonated apatite (CAP) in the presence and absence of citric acid, as a function of pH and thermodynamic driving force. While citric acid markedly accelerates the dissolution of TCP, HAP dissolution is significantly inhibited. Moreover, this additive has almost no influence on the dissolution of DCPD, OCP, and CAP. Dual constant composition dissolution studies of mixed calcium phosphates in the presence of citric acid have also been made. Another factor, pH, also plays an important role in the dissolution of these calcium phosphates. In suspensions of calcium phosphate mixtures, specific phases can be selectively dissolved by changing experimental parameters such as pH and the presence of rate modifiers. This result has important applications for the dissolution control of dental hard tissues such as dentin, enamel, and calculus.
authors.affiliation: Department of Chemistry, University at Buffalo, The State University of New York, Buffalo, NY 14260, USA.
authors.forename: Ruikang
authors.initials: R
authors.lastname: Tang
authors.forename: Michael
authors.initials: M
authors.lastname: Hass
authors.forename: Wenju
authors.initials: W
authors.lastname: Wu
authors.forename: Stacey
authors.initials: S
authors.lastname: Gulde
authors.forename: George H
authors.initials: GH
authors.lastname: Nancollas
mesh_terms: D002130:Calcium Phosphates / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D012995:Solubility; D013535:Suspensions / Q000737:chemistry
chemical_list: D002130:Calcium Phosphates; D013535:Suspensions