Drooling at the corners of the mouth can be caused by excessive saliva production or by difficulty swallowing. In the case of infants and young children, drooling may be a normal condition because the swallowing function of infants and young children is not fully developed; in the case of elderly patients with drooling at the corners of the mouth, it may be a symptom of Parkinson’s disease or dysfunction due to stiffness of the facial muscles. If there is a movable removable denture, it may lead to excessive saliva production, which may also occur at the corners of the mouth. If the teeth bite incompletely, such as open jaw or lateral chewing resulting in lateral open jaw and other symptoms, the parotid gland may also experience drooling when it is pressed for a long time. Patients are advised to go to the Department of Dentistry for orthodontic treatment and, if necessary, to the Department of Oral and Maxillofacial Surgery for surgical treatment in a timely manner.