Degradative analysis of glass ionomer polyelectrolyte cements.

As part of a detailed investigation of the setting mechanisms of dental polyelectrolyte cements, the Al3+, Ca2+, and Na+ concentrations in the matrix phase of glass ionomer cements were measured as a function of the cements age by use of a selective degradation technique. In the early stages of cement formation, all three cations were rapidly released from the glass, and it is inferred that both Ca2+ and Al3+ are responsible for gelation. Even after 5 X 10(4) min, the reaction was incomplete and still continuing.