A long white strip in the mouth may be a normal phenomenon, may be caused by pathological factors such as oral white keratosis, oral leukoplakia, oral leukoplakia, oral lichen planus and so on. 1. Physiological factors: long-term chewing teeth can produce buccal mucous membrane stimulation, the accumulation of time can cause buccal mucous membrane gray-white thread-like elevation called buccal white line, belong to the normal phenomenon of more than no need for treatment. 2.Pathological factors (1) Oral white keratosis: mostly related to vitamin A deficiency, stumpy roots and other stimuli, can cause superficial gray-white damage to the oral mucosa, which can be manifested as a white strip in the oral cavity, and the symptoms can be gradually relieved after removing the stimuli. (2) Oral leukoplakia: mostly related to smoking, Candida albicans infection, stumpy crown heel stimulation and other factors, which can cause white keratotic lesions on the oral mucosa, manifested as a white streak of symptoms in the mouth. (3) Oral lichen planus: a chronic inflammatory skin and mucous membrane disease, may be associated with viral infections, immune dysfunction, etc., can cause a long white strip in the oral cavity. After eliminating physiological factors, if the symptoms of white streaks in the mouth are not relieved, or even symptoms such as pain, it is recommended to consult a doctor in time to identify the cause and then actively treat it, so as not to delay the condition.