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Glass ionomer cements are a group of materials based on the acid/base reaction between poly(alkenoic) acid and an ion-leachable silicate glass. The material was developed in dentistry as a tooth restorative material that released fluoride ions over an extended time, bonded to tooth structure, and was very biocompatible. Its use in dentistry was initially limited by its slow setting time and lack of strength; however, modern formulations of the material have yielded materials with properties that are clinically useful in dentistry. Its biocompatibility, osteoconductive behavior, and ability to bond to bone and metals have generated interest in the material for medical applications. Glass ionomer cements in medicine have been used as bone cements, implants to replace ossicular bones of the inner ear, as well as other craniofacial implants. The early release of fluoride and aluminum ions and release of polyacids have been implicated in tissue biocompatibility in medical use. Additional material development is necessary to optimize its properties for use in medicine. This article reviews the literature written on the composition, chemistry, fluoride release, biocompatibility, and medical uses of glass ionomer cements.

The behaviour of decamethylcyclopentasiloxane (D5) in river water was evaluated by measuring concentration changes in open beakers. Effective values for the partition coefficient between organic carbon and water (K(OC)) were derived by least-squares optimisation of a dynamic model which accounted for partitioning between the sorbed and dissolved phases of D5, and for losses via volatilisation and hydrolysis. Partial mass transfer coefficients for volatilisation were derived from model fits to controls containing deionised water. Effective values of log (K(OC)) were between 5.8 and 6.33 (mean 6.16). These figures are higher than some other experimentally-derived values but much lower than those estimated from the octanol: water partition coefficient using single-parameter linear free energy relationships (LFERs). A poly-parameter LFER gave a predicted log (K(OC)) of 5.5. Differences in partitioning are believed to be due to the nature of the organic matter present. The new value for effective K(OC) was employed in a simple model of D5 behaviour in rivers to ascertain the extent to which a higher affinity for organic carbon would depress volatility. The results suggest that despite the revised K(OC) value, volatilisation of D5 remains a significant removal mechanism in surface waters.

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