Effect of sugar and sweetener on the bleachability of coffee and teainduced stains on composites: an <i>in vitro</i> experimental study

Objectives: This in vitro study evaluated the effects of various sugary and non-sugary beverages on the color change of a dental composite and the subsequent bleaching efficacy. Methods: Forty-nine disc-shaped composite samples (Neo Spectra ST, Dentsply Sirona) were split into seven groups at random (n = 7). Distilled water was used to hydrate each sample for 24 hours at 37°C. After 24 hours, the first color measurements (T0) were made by using a clinical spectrophotometer (VITA Easyshade Compact; VITA Zahnfabrik). Color measurements were repeated after 7 days (T1) and 14 days (T2) of immersion in distilled water (control), tea, coffee, sugary tea, sugary coffee, tea with sweetener added, and coffee with sweetener added. After staining for 2 weeks, the specimens were bleached for 6 hours a day for a week using 16% carbamide peroxide (Opalescence Ultradent Products). Color measurements were taken again after bleaching (T3). Using CIEDE2000, color differences (ΔE) were computed. Analysis of variance (ANOVA) and repeated measures ANOVA with a Tukey post hoc test were used to evaluate the data. Results: After 1 week, coffee-containing solutions produced significantly greater discoloration than the control (p < 0.001). By 2 weeks, tea groups exhibited similar discoloration to coffee groups (p < 0.001). The addition of sugar or sweetener had no significant effect (p > 0.05). Post-bleaching, coffee groups showed lower Whiteness Index values than the control, without statistical significance (p > 0.05). Conclusions: Coffee and tea markedly stain resin composites, with discoloration persisting post-bleaching, while sugar or sweetener additions exert no significant effect.