研究一种含过氧化物的美白牙膏对咖啡及茶渍色素去除的效果及差异。

选择2018年9月至2019年5月北京大学口腔医院综合科因正畸需要新鲜拔除的完整人双尖牙20颗，采用随机数字表法分为2组（咖啡溶液浸泡组与红茶溶液浸泡组），每组10颗。美白牙膏配制为牙膏溶液，使用200 g压力，100次/分钟频率，140次作为1个刷牙周期（相当于刷牙1周），连续刷牙8周。应用Crystaleye分光光度比色仪进行颜色测定。表面颜色测定选取的时间点为：基线、染色后及每个刷牙周期后。计算染色后及每个刷牙周期后与基线值之间，国际照明委员会（CIE）颜色的明度值之差ΔL_0-8*。各个样本染色后及每个刷牙周期后颜色与基线颜色之间的色差用ΔE_0-8表示，各组不同测量点组内差异应用配对t检验进行统计分析。各组组间差异应用ANOVA方差分析进行统计，P<0.05为差异有统计学意义。

咖啡溶液浸泡组及红茶溶液浸泡组，随着美白牙膏刷牙时间的延长，ΔE值较染色后逐渐降低。但直至美白牙膏刷牙第8周，仍无法恢复到基线水平。咖啡溶液浸泡组美白牙膏刷牙第1周起，牙齿颜色变化ΔE₁（5.2 ± 1.4）较染色后ΔE₀（6.1 ± 1.3）差异有统计学意义（t= 9.1，P<0.001）。红茶溶液浸泡组美白牙膏刷牙第4周起，牙齿颜色变化ΔE₄（5.6 ± 1.5）较染色后ΔE₀（6.4 ± 1.1）差异有统计学意义（t= 2.7，P= 0.025）。咖啡溶液浸泡组及红茶溶液浸泡组，离体牙样本明度值较基线值明显降低，从美白牙膏刷牙第1周起，ΔL₁*（-4.3 ± 0.9；-4.2 ± 1.0）较染色后ΔL₀*（-5.3 ± 0.9；-6.1 ± 1.2）差异有统计学意义（t_ΔL1*=-9.4，P_ΔL1*<0.001；t_ΔL0*=-12.1，P_ΔL0*<0.001）。

美白牙膏能够在一定程度上去除咖啡及红茶造成的牙面着色。其改善效果与使用时间成正相关。对于不同着色类型，美白牙膏去除外源性色素的效果不尽相同。

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.