Whether to brush your teeth or eat breakfast first in the morning should be decided according to the type of food you eat for breakfast. If you eat acidic food, you should brush your teeth before eating; if you eat non-acidic food, it is recommended to eat breakfast first and then brush your teeth. Usually, brushing should be placed after breakfast because food residues are prone to plaque bacteria, which can cause a series of oral diseases, and brushing can effectively remove most of the food residues in the teeth. However, if the intake of acidic beverages and food, it is recommended to brush first, after eating acidic food enamel wear resistance is reduced, at this time toothbrush friction may cause minor enamel damage, in the long run, the accumulation of damage prone to a variety of dental problems. Some people have bad odor in the mouth after waking up in the morning, which is a more common performance, several hours of sleep without opening the mouth, poor saliva and air flow in the mouth, especially oral and gastrointestinal diseases are more likely to have bad breath. It is recommended to brush your teeth before going to bed, which can remove food embedding in the mouth and food residues, reduce the growth of bacteria, and also reduce oral odor in the morning. If you eat non-acidic food, you can rinse your mouth before breakfast and brush your teeth after the meal, which may be able to properly alleviate the discomfort. In addition, you should maintain good dietary hygiene habits, pay attention to brush your teeth before going to bed, do not eat any food and beverage after brushing, and avoid containing acidic drinks or food in your mouth for a long time, which will increase the contact time between food and teeth, which is not good for oral health and may cause the occurrence of caries.