Enhanced anti-influenza virus activity of saliva following toothbrushing

Influenza, a respiratory infection caused by the influenza virus, has been associated with good oral hygiene, which correlates with a reduced incidence of the disease. Saliva possesses inherent antiviral properties against the influenza virus. However, the relationship between toothbrushing, a common oral hygiene practice, and the antiviral activity of saliva remains poorly understood. This study aimed to evaluate the effect of toothbrushing on the anti-influenza virus activity of saliva.

Sixteen adults without oral disease participated in this open-label, single-arm study. Resting saliva and mouth-rinsed water samples were collected before toothbrushing. Participants then brushed their teeth with a toothbrush and toothpaste for five minutes, after which additional saliva and mouth-rinsed water samples were collected at five minutes and one-hour post-brushing. The total bacterial amount in the mouth-rinsed water was measured by qPCR. The anti-influenza virus activity of saliva was determined using the TCID₅₀ method.

Saliva's anti-influenza virus activity increased significantly five minutes after toothbrushing compared to pre-brushing levels, but no significant difference was observed at 1 h, as follows [Δlog, median (min-max)]: Before brushing: 0.625 (-0.25-1.75), at 5 min: 1.25 (0.5-2), and at 1 h: 0.75 (0.5-2). A correlation analysis between total bacterial amount and antiviral activity revealed a negative correlation.

Improving the oral environment through toothbrushing enhances salivary antiviral activity. Maintaining oral hygiene may help prevent influenza virus infection.