College students orthodontics to the example of bad breath, there are 85% of bad breath from tartar, calculus, tooth decay, periodontal disease, infection around the wisdom teeth, loose tongue and broken fillings, unclean crowns, septic residue of teeth, smoking, the smell of food, etc.; the other 15% is nasal disease, lung, intestines, stomach, diabetes, kidney and other systemic diseases, so the maintenance of oral hygiene, regular maintenance and treatment It can solve most of the problems of bad breath. However, there is a causal relationship between the ease of oral hygiene maintenance and the neatness of tooth alignment. When a person’s teeth are not aligned, and other factors are the same, such as the length of time and method of brushing, and the degree of cleaning with a toothbrush is not as good as that of a person with straight teeth, the rate of dental-related diseases increases. It is easy to cause bad breath more often.