Evaluation of color stability of bulk-fill restorative materials with different properties

Aims: The present study aims to evaluate the color stability of bulk-fill restorative materials with different properties over different time periods when immersed in a coffee solution. Methods: According to the selected restorative materials, the study groups were formed as follows: CNT/light (Alkasite, Cention N, Ivoclar Vivadent, light cure mode), CNT/self (Alkasite, Cention N, self cure mode) EQF (Glass hybrid restorative, Equia Forte HT, GC Corporation), AU (Single-shade bulk fill, Aura Bulk Fill, SDI), Z550 (Filtek Z550, 3M) (control group). A total of 50 samples (n=10) were prepared using standard molds (2mmx10mm). After finishing and polishing procedures, all samples were kept in distilled water at 37°C for 24 hours. The first color measurement (L*a*b ) was performed with Vita Easy Shade V (VITA Zahnfabrik). Samples were added to the coffee solution. Color was measured at times simulating 7 days, 1 month, 6 months and 1 year of clinical service. Color changes (ΔE1, ΔE2, ΔE3 and ΔE4) were calculated according to the CIE L*a*b system. Normality of the data was examined by D'Agostino & Pearson omnibus normality test. One-way ANOVA analysis and Tukey test were performed. Statistical significance level was set at p 0.05 and statistical analysis software (GraphPad Prism 6.0, GraphPad Software, USA) was used for the analysis. Results: According to ΔE1 results; clinically unacceptable color change (ΔE>3.3) values were observed in CNT/light and CNT/self groups. The color change values of EQF, Z550 and AU groups were statistically similar (p>0.05). According to ΔE2 results; an unacceptable color change (ΔE>3.3) was observed in all groups except EQF. According to ΔE3 results; an unacceptable color change (ΔE>3.3) was observed in all groups. According to ΔE4 results; an unacceptable color change (ΔE>3.3) was observed in all groups. The color change values of EQF, Z550 and AU groups were statistically similar (p>0.05). CNT/light group showed the highest color change in all time periods, followed by CNT/self group. Conclusion: The color stability of single-shade bulk fill material and glass hybrid restorative materials is similar to the control group. The color stability of alkasite material needs to be improved.