title: Dimensional changes of alginate dental impression materials.
abstract: The weight loss and corresponding dimensional changes of two dental alginate impression materials have been studied. The weight loss kinetics indicate this to be a diffusion controlled process, but with a boundary condition at the surface of the concentration decreasing exponentially with time. This is in marked contrast to most desorption processes, where the surface concentration becomes instantaneously zero. The appropriate theory has been developed for an exponential boundary condition, and its predictions compared with experimental data; the agreement was satisfactory. The diffusion coefficients for two thicknesses of the same material were not identical as predicted by theory; the possible reasons for this are discussed.
authors.affiliation: IRC in Biomedical Materials, Department of Biomaterials in Relation to Dentistry, Medical Sciences Building, Queen Mary, University of London, Mile End Road, London, E1 4NS.
authors.forename: N
authors.initials: N
authors.lastname: Nallamuthu
authors.forename: M
authors.initials: M
authors.lastname: Braden
authors.forename: M P
authors.initials: MP
authors.lastname: Patel
mesh_terms: D000464:Alginates / Q000737:chemistry; D003102:Colloids / Q000737:chemistry; D003760:Dental Impression Materials / Q000737:chemistry; D020723:Glucuronic Acid / Q000737:chemistry; D006603:Hexuronic Acids / Q000737:chemistry; D008422:Materials Testing; D008956:Models, Chemical; D013816:Thermodynamics; D013997:Time Factors; D014867:Water / Q000737:chemistry
chemical_list: D000464:Alginates; D003102:Colloids; D003760:Dental Impression Materials; D006603:Hexuronic Acids; D014867:Water; D020723:Glucuronic Acid