Evaluation of Color Stability in One- and Multi-Shade Composite Resin Materials Polymerized with Different Curing Modes

Purpose: The aim of this in vitro study is to instrumentally compare the color stability of two different one-shade and a multi-shade universal composite resin material after light-cure in soft start (SS) and standard (ST) curing modes. Materials and Methods: Seventy-eight discs were prepared using two different one-shade composite materials (Omnichroma and Vittra Unique) and A2 shade of a multi-shade universal resin-based composite (Filtek Z250, 3M) when half of them was light-cured in ST and half in SS mode (n=13). The samples were placed in 5 ml of coffee solution and incubated at 37 °C for 30 days for the staining challenge. On the 1st, 7th, and 30th days, the measurements of L*, a*, and b* values were performed with a spectrophotometer and the color change was calculated by using the CIEDE2000 formula (ΔE00). Results: All materials exhibited significant and clinically unacceptable changes in color over time, regardless of curing mode (p < 0.05) and the maximum staining occurred in the first 24 hours and the first 7 days. Generally, the higher color change observed in the SS groups and Filtek Z250 statistically demonstrated the least staining. However, staining within the first 24 hours was not influenced by curing mode (p > 0.05). Conclusions: The curing mode and material type used for restoration may affect the amount of material staining caused by coffee consumption.