Color stability of recent hybrid and flowable resin composites

Objective: The purpose of this study was to evaluate color change of recent hybrid and flowable resin composites during water storage at 60°C. Methods: Three hybrid composites (Filtek Supreme A2, 3M-ESPE; SU, Solare A2, GC; SO, Palfique Estelite Sigma A2, Tokuyama; ES) and two flowable composites (Filtek Flow A2, 3M-ESPE; FF, UniFil Flow A2, GC; UF) were used in this study. Each of 5 specimens was placed in an acrylic ring (d=20mm, h=2mm). After light-curing for 60's and polished up to 1µm a using diamond paste, they were left at 37°C for 1 week before baseline measurement, and then stored in 60°C distilled water up to 4 weeks. After measuring CIEL*a*b* of each specimen, all specimens were repolished and measured again. Color change was determined by a fast spectrophotometric meter (CMS-35SP, Murakami color research laboratory). Data was analyzed using Kruskal-Wallis & Munn-Whitney U test (p<0.05). Results: DeltaE* values of resin composites significantly increased after 4 weeks storage. DeltaE* values of repolished resin composites significantly increased, compared to the baseline. DeltaE* values of ES showed significantly lower than that of SU and SO after 4 weeks 60°C water storage. Afer repolishig, deltaE* values of SO showed significantly greater than that of ES and FF. DeltaL* values increased after 4 weeks, and those returned to the baseline by repolishing. Deltaa* values increased after 4 weeks and after polishing. Deltab* values increased after 4 weeks and after repolishing except UF. Conclusion: DeltaE* values of resin composites significantly increased after 4 weeks in 60°C water storage though the color change was clinically acceptable. Even if the resin composites were repolished, deltaE* values of those remained significantly increasing.