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Updated: Jun 13, 2026

Impact of Common Fruit Juices and Toothbrushing on the Discoloration of Primary Teeth
Published on: March 27, 2026
[Neurophysiological effect of flavor and caffeine added to toothpaste]
Hidetoshi Sadachi1, Yoshinori Murakami, Manabu Hosoya
1Tokyo Laboratory, Kao Corporation, Tokyo 131-8501, Japan.
Objectives:
We previously reported that tooth brushing can be used for active resting as a fatigue-reducing method. In this study, we focused on toothpaste, aiming at increasing the fatigue-reducing effect of tooth brushing.
Methods:
Flavoring and caffeine were added to toothpaste, and their effects were investigated employing the Flicker value, event-related potential P300, and mood scale. Thirteen healthy male and female adults (6 males and 7 females, mean age +/- standard deviation: 28.2 +/- 6.5 yr) performed a 25-minute calculation task using a personal computer, brushed their teeth using the toothpaste, and then repeated the calculation task.
Results:
The P300 peak latency was significantly shortened after tooth brushing with the toothpaste containing flavoring and caffeine, compared to that after brushing with toothpaste containing no additives (p<0.01), and prolongation of the P300 peak latency after the calculation task was significantly inhibited (p<0.01). In addition, the accuracy of the calculation task tended to increase (p<0.1). Regarding the mood scale, "general fatigue" decreased (p<0.1), "lassitude" was significantly reduced (p<0.05), and "feeling of being refreshed" and "feeling of clear-headedness" were significantly increased (p<0.01 and p<0.05, respectively).
Conclusions:
These findings suggest the usefulness of tooth brushing with toothpaste with added flavoring and caffeine as a fatigue-reducing method.
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