The effect of time between curing and tea immersion on composite resin discoloration

One common cause for the replacement of a composite restoration is discoloration. This in vitro study evaluated the effect of tea solution on the discoloration of 3 types of composites at different timepoints after curing. For this study, 150 disc-shaped specimens of 3 types of composite resin-a nanohybrid (Filtek Z350), a microhybrid (Filtek Z250), and a microfilled material (Heliomolar)-were prepared. Specimens were randomly divided into 5 subgroups (n = 10) according to the type of composite and the time from curing to immersion in a tea solution (none [immersed immediately], 1 hour, 6 hours, 12 hours, or 24 hours postcuring). The color for all specimens was measured before and after immersion in tea. Color change (ΔE*) for all specimens was measured, and a ΔE* value of less than 3.3 was considered clinically acceptable. Analysis of variance and a post hoc Tukey test were used to analyze the data (α = 0.05). Immediately after curing, the levels of composite discoloration were deemed clinically acceptable (ΔE* < 3.3). In all composites, the greatest color change was found immediately after curing (P < 0.05). With each subsequent timepoint, the color stability increased. When the groups were immersed in tea 6 hours postcuring, the mean ΔE* value of the Filtek Z350 composite resin specimens was significantly greater than that of Heliomolar specimens (P < 0.05). The mean ΔE* value for specimens immersed 12 hours postcuring was also greater in the Filtek Z250 composite group than in the Heliomolar group (P < 0.05). The ΔE* values of Filtek Z350 and Filtek Z250 composites were not significantly different from each other (P > 0.05), except with 12-hour postcure immersion. The results suggest that patients should avoid the intake of staining foods or beverages for at least 12 hours after placement of a composite resin restoration, although this restriction may be reduced to 1 hour for microfilled composite resins.