During the day
Saliva plays an important role in oral hygiene in that it helps clear food particles from teeth, acts as a buffer against acids to prevent plaque formation, keeps teeth strong and healthy, and protects the oral cavity from invading bacteria.
During the night
When you sleep, you produce very little saliva, which can make your mouth dry. Without the protective effect of saliva, a dry mouth is more vulnerable to attack by bacteria, leading to the development of tooth decay, gum disease and bad breath. Therefore, to compensate for the low saliva production during sleep, it is advisable to carefully cleanse the mouth before going to bed and after sleep.