Early-age deformation, drying shrinkage and thermal dilation in a new type of dental restorative material based on calcium aluminate cement

Abstract

Dimensional changes during the first hour of hydration for small specimens of a dental material based on calcium aluminate cement (CAC) was examined. The study was conducted on specimens prepared in two different ways. First, intact tablets (three pieces per test) dipped in water were measured. Second, compacted specimens from four tablets were measured after 10 min of hydration. The dimensional changes were studied in both wet and dry conditions at 37 °C and in a dry condition at 25 °C. In the wet environment at 37 °C no dimensional change of the samples was observed. At normal room humidity (RH 55%) at both temperatures, shrinkage of 0.35–0.40% was observed. For comparison to the early-age drying shrinkage, a study of the drying shrinkage in mature material, hydrated for 50 and 100 days, respectively, was conducted. Furthermore the thermal expansion coefficient was determined and found to be close to that of tooth substance.