Influence of Tea-Induced Discoloration and Whitening Protocols on the Optical and Surface Properties of Resin Composites: An In Vitro Study.

PURPOSE: Resin composites are susceptible to extrinsic discoloration and surface alterations from beverages such as tea, as well as subsequent whitening treatments. This study aimed to evaluate the color stability (ΔE00) and surface roughness (Ra) of four resin composites after exposure to tea and whitening using either a mouthwash or a toothpaste. METHODS AND MATERIALS: Eighty standardized A1-shade discs were fabricated from Filtek Z350 XT (FZ), Herculite Classic (HC), G-ænial Anterior (G), and Asteria (A) (n = 20/group). Specimens were polished, stored in distilled water for 24 h, and baseline measurements were recorded (T0). All samples were immersed in freshly prepared tea for 6 days (T1) and then randomized into two whitening groups: immersion in Listerine Total Care mouthwash (MW) or brushing with a Colgate Optic White slurry (TP) for 6 days (T2a-T2b). Color was measured using a spectrophotometer, and Ra was measured using a profilometer. Data were analyzed using two-way repeated-measures ANOVA, Tukey post hoc tests, and partial eta-squared effect sizes (α = 0.05). RESULTS: All composites exhibited clinically unacceptable discoloration according to the contemporary CIEDE2000 acceptability thresholds (ΔE00 > 1.8), with HC and A reaching the extremely unacceptable category. Whitening resulted in partial color recovery, with MW outperforming TP (p 0.01). Surface roughness increased following whitening, especially in TP (ΔRa = 0.093 ± 0.024 µm). Large effect sizes were observed for both material and time factors. CONCLUSIONS: Tea staining significantly affected the color stability and surface roughness of all composite materials. FZ demonstrated the highest color stability, whereas HC showed the greatest discoloration and surface roughness. Whitening procedures partially reversed discoloration but did not restore baseline values. Overall, composites with finer filler structures exhibited better optical and surface properties compared with conventional hybrid composites.