Bad breath, also known as oral odor, refers to the unpleasant odor emitted by the oral cavity, which can be caused by a variety of reasons inside and outside the mouth. Among them, oral origin is the most common, or persists or occurs repeatedly, which is a major social problem that plagues many people. There are many reasons for bad breath, which can be divided into physiological factors and pathological factors. Physiological factors such as: decreased saliva secretion in the morning, eating some spicy food, some drugs (diyl sulfoxide) and smoking; pathological factors are divided into systemic factors and local oral factors. Systemic factors are mainly found in: certain respiratory diseases (sinusitis, rhinitis), digestive tract diseases (congenital tracheoesophageal fistula), diabetes, renal failure, etc. Oral local factors are the main cause of bad breath (56% to 90%), poor oral hygiene, gingivitis, and periodontitis are the common causes of bad breath; the tongue coating that exists in large numbers on the back of the tongue is the main place for bad breath; In addition, poor restorations, pericoronitis and deep cavities, and certain mucosal diseases can also cause bad breath. The main components of bad breath are volatile sulfides (VSC), mainly methyl mercaptan and hydrogen sulfide. VSC is produced by oral anaerobic microorganisms spoiling and metabolizing protein substrates.

After understanding the cause of halitosis, patients with halitosis should treat the cause. Halitosis caused by systemic factors should be treated for systemic diseases, and the halitosis can be relieved after the primary lesions are controlled. Oral cleaning measures such as brushing, rinsing and flossing can reduce bad breath caused by poor oral hygiene; while topical periodontal treatments such as scaling and scaling can improve breath and restore the health of periodontal tissues; remove tongue coating, especially on the back of the tongue The tongue coating, combined with the application of mouthwash can effectively reduce the level of VSC. Removing poor restorations and treating deep cavities can also help with bad breath.