According to the test, every time you brush your teeth, you can reduce 70% of the bacteria in your mouth, while rinsing can only reduce 15%. We advocate that in addition to brushing once in the morning, you should brush again at night before going to bed. You should not eat again after brushing your teeth at night. Most people only pay attention to brushing their teeth in the morning. In fact, brushing teeth at night is more important than brushing teeth in the morning. In fact, brushing at night is more important than brushing in the morning because during the day, people clean their teeth and inhibit the growth of bacteria by talking, eating with water and saliva secretion. After falling asleep at night, all the metabolism of human body is reduced, the mouth is in a static state, saliva secretion is reduced, and bacteria reproduction is accelerated, so in order to prevent tooth decay and periodontal disease, we should brush our teeth once at night before going to bed. In my opinion, it is enough to brush your teeth once in the morning and once in the evening, for three minutes each time, and to rinse your mouth after meals.