Tooth Discoloration Potential of Coffee With Common Additives and the Effectiveness of Whitening Toothpastes in Stain Removal.

OBJECTIVE: This study aimed to evaluate the influence of common coffee additives on tooth discolouration and assess the effectiveness of two commercially available whitening toothpastes in removing these stains. MATERIALS AND METHODS: Sixty bovine enamel specimens were randomly assigned to six groups (n = 10 per group) according to the coffee solution used: black coffee (control), coffee with sugar, stevia, Sweet'N Low, Splenda, or cream. Specimens were immersed for 7 days, and colour measurements were obtained every 24 h using a spectrophotometer and quantified using the CIEDE2000 colour difference formula (ΔE00). After staining, specimens were brushed with either a hydrogen peroxide-based toothpaste (V) or an abrasive-based toothpaste (WS) for up to 10,000 cycles, with colour measurements repeated during the brushing phase (1000, 3000, 5000). An additional 18 specimens (n = 3 per group) were sectioned to evaluate stain penetration depth using a microspectrophotometer. Colour change data were analysed using a linear mixed-effects model and one-way ANOVA with Tukey's post hoc test (α = 0.05). RESULTS: The linear mixed-effects model showed that tooth discoloration increased significantly with immersion time (β = 1.27, p < 0.001). A significant interaction between additive group and immersion time was observed for the cream group (β = -0.776, p < 0.001), indicating a slower rate of discoloration than the control. After 7 days, one-way ANOVA revealed significant differences among additive groups (p = 0.017), with the cream group showing the least discoloration (ΔE00 = 7.26 ± 2.34) and the Splenda group the greatest (ΔE00 = 14.48 ± 0.91). Brushing significantly reduced discoloration across cycles (β = 0.338, p < 0.001), but no significant differences were observed between toothpaste formulations (p = 0.443) or in the toothpaste-cycle interaction (p = 0.306). Cross-sectional analysis showed pigment penetration into enamel and dentine, with the cream group exhibiting the lowest subsurface discoloration. CONCLUSION: Coffee additives affect the degree of tooth discoloration, with cream showing a protective effect. Both whitening toothpastes were effective, but the hydrogen peroxide formulation generally performed slightly better, potentially due to its deeper stain removal capability.