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

<b>Objectives:</b> This study assessed the degree of conversion (DC), color, and dimensional stability, of three composite resins early after curing. <b>Materials and Methods:</b> 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 <i>L</i> ^{<i>⁣</i> ^<i>∗</i>} <i>a</i> ^{<i>⁣</i> ^<i>∗</i>} <i>b</i> ^{<i>⁣</i> ^<i>∗</i>} color parameters of each specimen and color change (<i>∆E</i>) were measured at the aforementioned time points. Dimensional changes were measured by a digital micrometer. Respective ANOVA and Tukey tests were used for analysis. <i>p</i> < 0.05 was considered significant. <b>Results:</b> All composites exhibited an increased DC and expansion over time (<i>p</i> < 0.001). At 1 month, the <i>∆E</i> 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 <i>∆E</i> than Filtek Ultimate (<i>p</i> = 0.02). No other significant differences were found. <b>Conclusion:</b> 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.