Acid-base complex reactions in resin-modified and conventional glass ionomer cements.

摘要

Resin-modified glass ionomer cements are a recent development in which the desirable properties of glass ionomer cements and resin-composites are combined. The presence of resin may, however, retard the acid-base reaction of the ionomer component. This has led to a debate regarding the classification of resin modified materials as true glass ionomer cements, and the actual duration of the acid-base reaction after initial setting via light polymerization has taken place. To investigate this issue, a novel method employing FT-IR spectrophotometry was used to monitor the acid-base complexation reaction in a resin-modified glass ionomer cement (Fuji II LC) and a conventional, chemically cured cement (Fuji II Cap). This method involved subtraction of the background "resin" spectrum from the Fuji II LC spectra and subsequent application of a baseline to obtain the plot of absorbance area ratio in the range of 1685 to 1510 cm(-1) (complexed carboxyls) to that in the range of 1750 to 1685 cm(-1) (free carboxyls). This study demonstrates evidence of a delayed acid-base reaction for the resin-modified cement, which levels off after 168 hours of cement mixing. In contrast, the complexation reaction of the conventional glass ionomer cement was essentially complete after 24 hours. Copyright 1999 John Wiley & Sons, Inc.