Experts tell us that people should brush their teeth after getting up in the morning and before drinking water. This is because people will leave some food residues or dirt on their teeth before brushing their teeth in the morning. These residues or dirt are easy to form dental plaque and tartar after combining with calcium salts in saliva. If people drink water first after getting up in the morning, they will bring these bacteria and dirt into their bodies and do harm to their bodies. In addition, some people worry that brushing your teeth first will take away digestive enzymes in saliva, thus affecting digestive function. In fact, this kind of worry is completely unnecessary. Digestive enzymes in saliva only work when people eat, and they are always in a "rest" state. Moreover, when people sleep, saliva secretion will decrease, so they produce few digestive enzymes. Therefore, brushing your teeth after getting up in the morning will not affect people's digestive function. Refreshing experts remind you that brushing your teeth every morning and evening can effectively prevent bad breath. A glass of water in the morning is good for your health.