The Efficacy of 10% Carbamide Peroxide in Reversing Common Dietary Staining on Resin Infiltrated White Spot Lesions: An In Vitro Study

White spot lesions (WSLs) are a common aesthetic concern and can be managed in a minimally invasive manner via resin infiltration to enhance their appearance. However, resin-infiltrated teeth may discolour over time due to dietary stains, posing a potential long-term aesthetic challenge. This in vitro study aims to evaluate the effectiveness of 10% carbamide peroxide on resin infiltrated WSLs following staining by common dietary sources. Forty-four extracted premolars with artificially created WSLs were infiltrated with resin and randomly distributed into four groups, including a control group. The specimens underwent staining with coffee, tea, and turmeric before bleaching with 10% carbamide peroxide for 14 days. Colour parameters were measured via spectrophotometer using the CIE L*a*b* system, and the colour changes (ΔE) across timelines were calculated. All of the specimens were susceptible to staining, with evidently high ΔE values. Following the bleaching protocol, all specimens showed statistically significant increases in L* (lightness) compared to the baseline. The post-bleaching colour change (ΔE) was compared to the baseline ΔE = 0, and the results indicated that full reversion was not achieved. Turmeric exhibited the highest stainability and the greatest resistance to bleaching. Within the limitations of this study, resin-infiltrated enamel was shown to be susceptible to dietary staining. Although full reversion to the baseline colour remains challenging, the marked aesthetic improvements indicate that resin-infiltrated enamel remains highly responsive to low-concentration bleaching agents.