Effects of aging on shear bond strength to dentin and mechanical properties of restorative glass ionomer cements

Abstract

ObjectivesTo evaluate the shear bond strength to dentin (SBS), flexural strength (FS), and diametral tensile strength (DTS) of four restorative glass ionomer cements after aging in artificial saliva. Materials and methodsFor SBS testing, sound molars were ground to flat occlusal dentin and fixed with acrylic resin. Teeth were randomly divided into four groups along with the following materials: Ketac Nano, Ketac Molar, Fuji II LC and Equia. Glass ionomer cylinders were bonded to each dentin surface. For testing the mechanical properties, FS bars (25 mm × 2 mm x 2 mm) and DTS discs (4 mm × 2 mm) were fabricated. All specimens were stored in artificial saliva (37 °C) and tested after 24 h and 6 months. Data was analyzed with two-way ANOVA and post-hoc Tukey's tests (α = 5%). ResultsThe SBS results were statistically similar among the four glass ionomer cements (p > 0.05). No significant differences in SBS after 24-h and 6-month storage were found, except for in the Ketac Nano group, where a significant decrease in SBS was found after aging (p < 0.05). All materials had a significant increase in FS after aging. The DTS values did not change significantly after aging, with the exception of the Fuji II LC group. Overall, the Fuji II LC group showed significantly higher DTS and FS compared to the other materials. ConclusionsAging for 6 months did not affect the SBS of restorative glass ionomer cements, except in the case of Ketac Nano. All glass ionomer cements showed increased FS over time. The DTS remained unchanged – except for the Fuji II LC, which experienced increased DTS.