Color Stability of Composite and Glass Hybrid Restorations in Storage Media Recommended for Avulsed Teeth: An In Vitro Study

Tooth avulsion is one of the most severe dental injuries, and appropriate storage media are essential for preserving avulsed teeth before replantation. However, little is known about the effects of these media on the color stability of existing restorative materials. This in vitro study evaluated the color stability of a composite resin and a glass hybrid restorative material immersed in six storage media commonly recommended for avulsed teeth. A total of 120 disc-shaped specimens were prepared and allocated to dry environment, artificial saliva, tap water, cow’s milk, goat milk, and kefir groups. Color measurements were performed using the CIE L*a*b* system at baseline, 30 min, 1 h, 6 h, 12 h, and 24 h, and color change (ΔE) values were calculated. Data were analyzed using a linear mixed-effects model with restorative material, storage medium, and time as fixed effects and specimen ID as a random effect. Color change increased significantly over time in all groups (p < 0.001). Glass hybrid restorations exhibited significantly higher ΔE values than composite restorations across most storage media and time points (p < 0.001). Significant material–medium–time interactions were observed (p < 0.001), indicating that the effects of storage media varied according to restorative material and exposure duration. Dry storage conditions were generally associated with the highest color changes. Within the limitations of this study, the tested composite restorative material (G-ænial Posterior) demonstrated greater short-term color stability than the tested glass hybrid restorative material (EQUIA Forte HT) in the evaluated storage media.