The causes of a dry mouth may be dry syndrome, lingual inflammation, oral mucous membrane diseases, etc. 1. Dry syndrome: a chronic autoimmune disease in which inflammatory cells infiltrate the salivary glands and secrete less saliva, which can lead to a dry mouth. Oral dryness syndrome includes symptoms of rampant dental caries, mumps, sore tongue, atrophy of the tongue papillae, and mouth ulcers. 2. Tongue inflammation: it is a chronic non-specific inflammation, tongue papilla atrophy causes numbness and burning pain in the tongue, and dryness in the mouth occurs. 3. Oral mucosal diseases: oral candidiasis, oral leukoplakia, etc., the fungus causes the oral mucosa to fall off, there can be a wooden astringency in the oral area, dry and sticky mouth, loss of taste and other manifestations. To identify the specific causes of astringency in the mouth, should go to the hospital, the doctor combined with the relevant examination, diagnosis.