The purpose of the present study was to clarify the long-term effects of frequent chewing of unflavored and odorless gum (hereafter, gum base) on oral hygiene and mental health. This single-arm study, which started with a 4-week control and ended with a 4-week intervention period, was conducted in two phases: one in 2017 and one in 2018. The participants comprised 36 dental hygiene students (17 in 2017, 19 in 2018). During the intervention period, all participants were required to chew a piece of gum base 7 times a day for 10 min each time. The unstimulated salivary flow rate and masticatory efficiency were measured and chewing number counted. Two questionnaires －the Profile of Mood States, second edition (POMS2) and the 30-item General Health Questionnaire (GHQ-30)－ were administered to assess mental health. In both phases, the unstimulated salivary flow rate showed a significant increase after the intervention period (p<0.05). In 2017, the GHQ-30 scores and masticatory efficiency showed a tendency toward a negative correlation after the intervention period (r=－0.4647, p=0.06). In 2018, a significant negative correlation was observed between chewing number and the POMS2 scores after the intervention period (r=－0.6296, p<0.01). These findings suggest that frequent chewing of gum base increases unstimulated salivary flow rate. However, no significant change was observed in the mental health.
Keywords: Chewing gum; Mental health; Salivary flow rate; Single-arm study.