Journal of Dental Research, Vol 55, 489-495, Copyright © 1976 by International & American Associations for Dental Research Online Journals
Reactions in glass-ionomer cements: IV. Effect of chelating comonomers on setting behavior
A. D. Wilson, S. Crisp and A. J. Ferner
The oscillating rheometer is a valuable instrument for studying the effects
of additives on the setting behavior of a cement system. Using this
instrument, it was found that certain chelating comonomers, the
hydroxycarboxylic acids, could improve the setting characteristics of the
glass-ionomer cement system when added to the PAA solution. The acid
chelates probably assign the extraction of metal ions from the glass and
also tend to hold them in solution, preventing premature ion binding of the
polyanion chains. The effect is to increase the rate of hardening without
reducing the working time, which may indeed by slightly increased. Tartaric
acid, the most effective of the comonomers, can form a chelate bridge
between aluminum atoms, and this metal complex probably acts as a flexible
bridge structure linking polyanion chains. This mechanism offers some
steric advantages over a simple salt bridge.
