Purpose. This study evaluates the effect of bleaching before or after veneer preparation and the depth of preparation on color masking ability of laminate veneers. Methods. Sixty extracted premolars were artificially stained to vita shade A4, verified by digital spectrophotometer (Vita Easy Shade V), and then divided into three groups: NB = nonbleached, BBP = bleaching before preparation, and BAP = bleaching after preparation. Based on the preparation depths, each group was further divided into two subgroups: S1 = 0.5 mm and S2 = 1.0 mm. BBP and BAP were subjected to one session of in‐office bleaching using 35% hydrogen peroxide. IPS e‐max CAD veneers of 0.5 and 1.0 mm thickness (corresponding to the preparation depths) of the same shade and translucency (HT A1) were cemented immediately to the bleached surfaces. Immediately after cementation, the color change ΔE between the baseline (after staining) and the resulted shades was measured using the Vita Easy Shade V digital spectrophotometer and CIELab color system. Results. Bleached groups exhibited a significant ΔE value compared to the nonbleached group (p < 0.05). BAP showed the highest ΔE value. No significant difference was found between BBP and BAP. S2 revealed a significant ΔE value than S1 (p < 0.05). No significant difference was found between S1of BAP and S2 of NB, BBP, and BAP (p > 0.05). Regarding the color coordinates, the difference between the tested groups was highly significant in lightness (ΔL∗) (p < 0.001), while no significant differences were found in green/red value (Δa∗) and yellow/blue value (Δb∗) (p > 0.05). Conclusions. In cases of severe tooth discoloration, one session of in‐office bleaching before or after veneer preparation and the preparation depth do not influence the color masking ability of laminate veneers.

Dental composites are ceramic-reinforced polymers; however, their colour stability is crucial for clinical maintenance, as composite restorations are inherently susceptible to colour change over time. In this in vitro study, eighty standardised 3D-printed samples were fabricated, filled with one of two supra-nanospherical resin composites, divided according to two polishing protocols (standard and reduced), and immersed in black tea with or without sugar for 28 days, after which they were repolished. Colour measurements were performed using a spectrophotometer at baseline (T₁), after tea immersion (T₂), and after repolishing (T₃). Statistical analysis was performed using a three-way repeated-measures mixed ANOVA followed by a Bonferroni post hoc test. The colour outcomes were interpreted against the CIEDE2000 50:50% perceptibility threshold (PT₀₀ = 0.8) and acceptability threshold (AT₀₀ = 1.8). Given the constraints of this in vitro investigation, all specimens exhibited initial discolouration (ΔE₀₀1 = 5.85 ± 1.63) that exceeded the acceptability threshold. Following repolishing, overall discolouration was significantly reduced (5.64 ± 1.46), achieving a final recovery (ΔE₀₀3 of 0.92 ± 0.56) near the perceptibility threshold. Although Tokuyama PALFIQUE^® LX5 might have exhibited lower ΔE than Estelite^® Alpha, the choice of composite had no statistically significant impact. Conversely, polishing methods and sugar content significantly influenced the outcomes (p < 0.05). Specifically, the standard method consistently resulted in final residual colour differences below the perceptibility threshold (ΔE₀₀3 ≤ PT), whereas the reduced method resulted in values exceeding this threshold. Furthermore, exposure to sucrose resulted in significantly greater residual staining post-treatment compared to plain black tea. Within the limitations of this in vitro study, the findings suggest that while composite selection between similar supra-nanospherical resins does not significantly affect aesthetic longevity, the standard method effectively maintains final residual colour shifts within imperceptible clinical boundaries. Moreover, dietary sucrose may contribute to greater permanent residual staining after repolishing. Nonetheless, as these observations derive from an in vitro model lacking a natural salivary pellicle and biofilm, clinical in vivo validation is required before direct extrapolation to daily dental practice.