A simple acid erosion test for dental water-based cements

Objective: The aim of the study was to evaluate a new erosion test for dental cements that has been developed as an alternative to the impinging jet erosion test used in current standards. The method was evaluated by measuring and comparing the extent of the erosion of three different types of dental cement. Methods: The erosion of three different types of cement; zinc phosphate, polycarboxylate and glass ionomer, were evaluated by measuring the depth loss of the cement placed in a cylindrical cavity in PMMA sheet after immersed in lactic acid solution (pH 2.74) or lactic acid/sodium lactate buffer solution (pH 2.74). The depth loss was measured by a dial gauge. Changes in the pH of the eroding solutions were monitored. Identical specimens were immersed in distilled water and the degree of hygroscopic expansion was also confirmed. Results: Depth loss and pH increased with increasing immersion period. The depth losses of all cements were considerably more in the buffer solution than in the acid solution. A difference in the eroded depth for three different kinds of cements clearly emerged. The depth loss for polycarboxylate was more than that for zinc phosphate, which was more than that for glass ionomer. Although hygroscopic expansion was observed for glass ionomer, the value after 24 h immersion was negligible compared with the eroded depth. Significance: The results appear to correlate with those obtained using a jet erosion test and with published data on clinical performance. This suggests that the simpler test described here is suitable for standardization purposes. (C) 2001 Published by Elsevier Science Ltd on behalf of Academy of Dental Materials.