ADSORPTION OF NEUTRAL AND ANIONIC POLYACRYLAMIDES ON HYDROXYAPATITE AND HUMAN ENAMEL - INFLUENCE ON THE DISSOLUTION KINETICS

The adsorption of polyacrylamide fractions of different molecular weig hts and degrees of hydrolysis on hydroxyapatite and dental enamel, as well as their influence on the kinetics of dissolution of the latter, are studied at a constant pH under well controlled conditions. It is s hown that the adsorbed polymers can slow down the dissolution process. The intensity of the inhibition effect follows the characteristics of the adsorption layer. The inhibition increases with the molecular wei ght of the polymers and their degree of hydrolysis. These behaviors ar e well interpreted with the model of apatite dissolution recently prop osed, which supposes the formation of a cationic semipermeable layer, formed by the adsorption of calcium ions at the apatite interface. (C) 1994 Academic Press, Inc.