Effect of Expiry Date on the Degree of Conversion, Microhardness, Depth of Cure, Water Absorption and Color Stability of Resin Composite

Objectives: To evaluate the degree of conversion, microhardness, curing depth, water absorption and color stability of expired and non-expired resin composite materials.Methods: Five different resin-based materials, Ceram.X Spheretec One (CRX), Beautiful II (BEA), SonicFill 2 (SCF), GrandioSo Heavy Flow (GSF) and SDR, with and without expiry dates, were used in the study. The degree of conversion was analyzed using ATR-FTIR spectrometer. For microhardness measurement, Vickers hardness test device was used. Microhardness of the RBCs was measured at 0.5 mm intervals starting from the top surface towards the bottom layer for depth cure measurement. Samples were immersed in water for water sorption analysis and in red wine and coffee for one week for color stability analysis. Statistical analysis was performed using one-way ANOVA, independent sample t-test, Tukey HSD test, Kruskal-Wallis, Mann-Whitney U test.Results: Only in the BEA group did expired samples show a lower degree of conversion and microhardness (bottom/top) than non-expired samples (p