Properties of Composite Resins Early After Curing: Color Stability, Degree of Conversion, and Dimensional Stability.

Objectives

This study assessed the degree of conversion (DC), color, and dimensional stability, of three composite resins early after curing. Materials and

Methods

This study was conducted on X-tra fil, Filtek Z250, and Filtek Ultimate composites. To measure DC, the absorption spectra of composites before and after curing (immediately, 15 min, 2 h, 6 and 24 h, 1 week, and 1 month) were recorded by ATR-FTIR. Fifteen specimens were fabricated for each composite and assigned to two experimental groups (15 min immersion in coffee immediately and 2 h after curing) and a control. The CIE L ⁣ ∗ a ⁣ ∗ b ⁣ ∗ color parameters of each specimen and color change (∆E) were measured at the aforementioned time points. Dimensional changes were measured by a digital micrometer. Respective ANOVA and Tukey tests were used for analysis. p  < 0.05 was considered significant.

Results

All composites exhibited an increased DC and expansion over time (p  < 0.001). At 1 month, the ∆E of composites immersed in coffee after 2 h was not significantly from the control group. In the immediate coffee immersion group, X-tra fil experienced significantly greater ∆E than Filtek Ultimate (p = 0.02). No other significant differences were found.

Conclusion

Time of exposure to coffee after curing had a significant effect on the color stability of X-tra fil only. X-tra fil showed minimum dimensional changes after 1 month.