pH Determinations on the Surface of Luting Cements

II. Effects of Test Conditions

Abstract

The pH changes of small amounts of test solutions which were in contact with luting cement surfaces during setting were determined using a flat combination electrode. The effects of 1) time intervals between the start of mixing and water contact, 2) different compositions of test solutions and 3) different types of filter were examined. The results showed that the initial rate of pH change for each cement became slower as the time interval between start of mixing and water contact increased. Polycarboxylate cement was the least acidic and showed the highest neutralization rate for each test solution. For both NaHCO₃ solution and human saliva, the initial rate of pH change of each cement was lower than that for other test solutions such distilled water, NaCl solution and albumin solution. Additionally, the pH change of the test solution varied with the type of filter placed between the cement surface and the pH-sensitive surface of the electrode.