Whitening Efficacy and Post-Whitening Color Stability of an LED-Assisted Over-the-Counter Whitening System: An In Vitro Study

This in vitro study assessed tooth color and whiteness changes following application of a commercial LED-assisted over-the-counter (OTC) whitening system, and characterized subsequent color changes under different immersion conditions. Sixty extracted human maxillary incisors were whitened once daily for 15 consecutive days in ten six-tooth acrylic arch models. After whitening, the models were randomly allocated to five immersion conditions (two models; n = 12 teeth per condition): distilled water, black tea, coffee, cola, and red wine. Specimens were immersed in the assigned medium for 4 h daily for 15 days using a single shared container per group. Tooth color was measured with a spectrophotometer at baseline (T0), after whitening (T1), and after staining (T2). Color change was assessed using CIEDE2000 (ΔE00), the Whiteness Index for Dentistry (WI_D), and supportive ΔEab values. Mean WI_D increased from 15.66 ± 5.14 at T0 to 26.23 ± 5.67 at T1 (p < 0.001), with a mean ΔWI_D of 10.58 ± 1.97 and ΔE00 of 5.00 ± 0.87. All specimens exceeded the 50:50 acceptability thresholds for both outcomes. Descriptive post-whitening color changes varied across immersion conditions, including distilled water; however, the absence of independent container-level replication precluded valid inferential comparisons between staining media. Red wine showed the highest mean ΔE00 (16.13 ± 3.42), whereas cola showed the largest numerical loss of whiteness. The complete commercial whitening system was associated with a measurable increase in dental whiteness, whereas subsequent color changes represented descriptive laboratory observations rather than independently confirmed beverage effects.