Physical and Chemical Aspects Related to Substances Released from Polymer Materials in an Aqueous Environment

Abstract

Exposure to an aqueous environment will change the physical properties of polymer materials with time. Due to water absorption, surface hardness is reduced and mechanical properties are adversely affected. The composition of polymer dental materials varies greatly. The organic substances are represented by monomers, oligomers, polymers, initiators, activators, inhibitors, anti-oxidants, UV stabilizers, plasticizers, fluorescent compounds, and other additives. The inorganic substances are represented by oxides and glasses (fillers and pigments) of various composition. Both organic and inorganic substances are released into water from composite materials. Combined-HPLC/UVspectroscopy analysis of an aqueous extract from a composite filling material demonstrates that the eluate contains several components. Several inorganic metal-ions released into aqueous solutions have been identified. Only a few of the released organic substances have been identified. Several investigators have determined the quantity of residual monomers in the polymerized materials, and the decrease of such residual monomers with time. Exposure to water, or aqueous salivary enzyme solutions, results in release of degradation products, such as formaldehyde, methacrylic acid, and others.