To compare the effect of a peroxide-containing whitening toothpaste on the removal of coffee and black tea stains.

A total of 20 double-cuspid teeth that needed to be removed due to orthodontic treatment were collected from Department of General Dentistry, Peking University School and Hospital of Stomatology, from Sep. 2018 to May 2019, and divided into two groups using the random number table method, i.e. coffee and black tea groups. A toothpaste solution was prepared with whitening toothpaste, where the teeth were brushed with a pressure of 200 g and a frequency of 100 strokes/min. During the brushing, 140 strokes were set as a brushing cycle, and eight continuous cycles were taken. Color analysis of each tooth was performed using a Crystaleye spectrophotometer. Surface color was determined before and after staining, and at the end of each brushing cycle (t1-8) . The change in the lightness of the color (Commission International d′Eclairage, CIE) between each time points was marked as ΔL_0-8, while the color difference was ΔE_0-8. Data between time points and groups were analyzed with paired t test and ANOVA, respectively. A significant level was set at 0.05.

The ΔE value of both the coffee and black tea groups was found to gradually decrease as the brushing time extended. However, it was not possible to return to the baseline even after the 8th week of brushing. For coffee solution group, the tooth color change ΔE₁ (5.2 ± 1.4) was significantly different from the first week (6.1 ± 1.3; t= 9.1, P<0.001) . But for black tea group, the tooth color change ΔE₄ (5.6 ± 1.5) was significantly different from the fourth week (6.4 ± 1.1; t= 2.7, P= 0.025) . For both the coffee and black tea group, the brightness value was significantly lower than the baseline. The change of the brightness from the first week of whitening toothpaste brushing (ΔL₁*, -4.3 ± 0.9; -4.2 ± 1.0) showed a significant difference from the point of staining (ΔL₀*, -5.3 ± 0.9; -6.1 ± 1.2; t=-9.4; t=-12.1, P<0.001) .

Whitening toothpaste could remove tooth surface staining caused by coffee and black tea to some extent. The improvement effect was positively related to the time of use and also seemed dependent on the stains.