Strain field measurements of glass ionomer cement

Abstract

Extensive evolution of glass ionomer cements (GIC) has marked a significant shift in the practice of luting indirect dental restorations limiting the use of zinc-phosphate and zinc-polycarboxylate cements to a few indications. GIC are now one of the materials of choice for cementation of all ceramics, fiber reinforced composite posts and veneers. GICs are determined by unique properties like chemical adhesion to tooth and base metals, low thermal expansion coefficients similar to dentin and minimal microleakage at the tooth-enamel interface due to low shrinkage. Shrinkage strain is identified as the cause, and the associated stress as the mechanism for the loss of marginal adaption and cohesive fracture within the material. The aim of this study is to measure the strain and displacement field in a conventional GIC (Riva Luting, SDI, Australia) related to different cement diameter, using 3D Digital Image Correlation (DIC) method. The experiment is done for samples with thickness of 1 mm combined with diameters of 4 mm (Group I) and 3 mm (Group II). The strain field is measured using 3D 11optical system Aramis 2M (GOM, Braunschweig, Germany). This study provides valuable data about strain behaviour and displacement as a possible failure factor in GIC, Riva Luting. Visible differences between Group I and Group II were observed.