Color Stability of Bulk-fill Resins Immersed in Chicha: In vitro Study.

Objective: To analyze the color stability of Bulk-fill resins immersed in chicha morada and light-cured at different distances (0 mm, 2 mm and 4 mm).

Methods: This in vitro experimental study included a total of 216 Bulk-fill resin discs. The specimens were distributed into nine groups of 24 discs based on the type of resin (3M ESPE^® Filtek™ Bulk Fill^®, Ivoclar^® Tetric N-Ceram Bulk Fill^® and FGM^® Opus Bulk-fill APS^®), light-curing distances (0, 2 and 4 mm) and staining solution (control with distilled water and Naturalle^® chicha morada). Color measurements were taken 24 hours after fabrication and immersion in distilled water and Naturalle^® chicha morada at 24 hours, 1 week and 3 weeks.

Results: Light-curing distances affected the color stability of the resins with 3M ESPE^® and Ivoclar^®, ^thus exhibiting significant color changes at all evaluated time points when immersed in chicha morada. For the Delta (ΔE) value 3M ESPE^® and Ivoclar^® resin discs immersed in chicha morada showed significant changes at 24 hours 1 week and 3 weeks (p = .001, p = .000 and p = .000; and p = .000 p = .000 and p = .000 respectively). However, FGM^® resin discs exhibited significant changes only at 24 hours and 1 week (p = .000 and p = .001). FGM^® showed better color stability compared to 3M ESPE^® and Ivoclar^® at 3 weeks of immersion in chicha morada. All three commercial brands showed a significant decrease in the "L" value as immersion time in chicha morada increased.

Conclusions: The study concluded that FGM^® demonstrated better chromatic stability over time compared to 3M ESPE^® and Ivoclar^® Ceram, which exhibited significant color changes influenced by immersion duration and photopolymerization distance.