Abstract: Limited mouth opening refers to a clinical manifestation that the distance between the upper and lower dentition is significantly reduced when opening mouth. It is mostly caused by limited movement of the temporomandibular joint, which can affect the patient's chewing, swallowing, speech, oral hygiene and other oral and jaw functions. Long-term inability of mouth opening to eat normally may lead to malnutrition, and even severe physical and mental disabilities, affecting the quality of life. Nowadays, clinical medical workers have not yet payed enough attention to the causes and therapies of limited mouth opening. Therefore, this paper reviewed the measurement, classification, etiology, prevention and treatment methods, risk and prognosis of patients with limited mouth opening, aiming to strengthen the attention of medical staff to patients with restricted mouth opening, so as to achieve early diagnosis, prevention and treatment.

Key words: Limited mouth opening, Temporomandibular joint, Masticatory muscles, Mouth opening training