pH Determinations on the Surface of Luting Cements

The pH changes of small amounts of distilled water in contact with the surface of samples of dental luting cement were determined by using a flat combinetion electrode. The results showed that the initial pH value and the neutralization rate of the water in contact with the cement surface decreased with both decreasing amounts of water and the time interval between cement mixing and contact with water. Initial pH value and the neutralization rate for polycarboxylate cement was higher than those for zinc phosphate and glass ionomer cements. This suggests that the water in contact with polycarboxylate cement is rapidly neutralized because of the relatively small release of acid from the cement after initial setting.