Efficacy of Using Aroma Mouthwash in Recoverying from Short-term Cognitive Stressor

Mouthwash prevents bad breath and sterilizes bacteria that cause dental caries and periodontal disease, so it provides important means for improving oral hygiene in our daily life. Along with active ingredients such as bactericides, mouthwash contains a variety of aromas to mask the bitterness of base ingredients and increase palatability. However, given that numerous aroma studies have demonstrated various physiological efficacies of aromas on autonomic/central nervous systems, it is no wonder that aroma mouthwash has some sort of physiological impact when it is used. In this study, we investigated the effect of aroma in mouthwash on peripheral and cardiac autonomic nervous system activity. The experiment was carried out in a within-subject design wherein 20 healthy women under 5 conditions, which are 4 types of mouthwashes: peppermint, peppermint + bergamot, peppermint + orange, and peppermint + lavender, and water as a control. Participants performed a 20-minute calculation task as a cognitive stressor, and then rinsing by a mouthwash or water. We evaluated the recovery period from acute stress response for 20 minutes after the task. As a result, it was observed that a mouthwash with citrus flavor had a relaxing effect in terms of subjective scores and recovering from physiological stress response. The results may illustrate a potential benefit of using aroma mouthwash.