<Things you should know> Correct knowledge about "mouth ulcers" (1) Explanation of the causes and symptoms of "mouth ulcers" What is a canker sore? Causes of mouth ulcers Main types and symptoms of mouth ulcers Diseases that are similar to/related to mouth ulcers Mouth ulcers, though often referred to simply as "canker sores," can have a wide variety of causes and symptoms. Sometimes, they can even be a symptom of a more serious underlying illness, so it's important to have accurate knowledge about them. This article, supervised by a dentist, explains the common causes and symptoms of mouth ulcers. What is a canker sore? Stomatitis is inflammation of the mucous membranes inside the mouth, such as the cheeks, lips, the inside of the upper palate, the tongue, the area under the tongue (floor of the mouth), and the gums. When the area of symptoms is limited, it may be called "gingivitis," "glossitis," "cheilitis," or "angular cheilitis," depending on the affected area.Mouth ulcers primarily present with the following symptoms: The mucous membrane turns red (redness) Swelling (edema) Whitening (vitiligo) The surface of the mucous membrane hardens (induration). To become ulcerated (eroded) The surface of the mucous membrane peels off or becomes eroded (ulcer). Blisters may form (vesicles), etc. Causes of mouth ulcers The causes of mouth ulcers are diverse, but they can be broadly categorized into local causes, systemic causes, and those with unknown causes. Local cause Trauma (such as injuries from chipped teeth due to decay, tartar, sharp teeth, fillings, brushing, or biting the inside of the mouth) temperature stimulation Chemical irritants such as drugs Infections caused by bacteria (tuberculosis, syphilis, gonorrhea, etc.), fungi (so-called mold, Candida), viruses (herpes simplex, Coxsackie virus, enterovirus, measles, chickenpox, etc.) Allergies (such as metals or materials in fillings, crowns, and dentures), etc. Systemic causes Decreased physical strength (decreased resistance) stress Nutritional disorders due to deficiencies in B vitamins, folic acid, iron, etc. Systemic diseases (blood disorders: AIDS/HIV infection, anemia, etc.; autoimmune diseases: systemic lupus erythematosus, pemphigus, bullous pemphigoid, etc.) Radiation therapy, etc. Cause unknown Behçet's disease, Crohn's disease, lichen planus, etc. *The section on "Etiology of stomatitis" is quoted and adapted from the literature "Katsuhide Inagi, Kiyoshi Shibuya: Local Therapy for Stomatitis. JOHN, 15:649-654, 1999".*While some cases of mouth ulcers are clearly caused by infections, many others have unknown causes. The mechanisms by which mouth ulcers develop are not fully understood. People who are prone to mouth ulcers Elderly people, infants, and those with dry mouth are more prone to developing mouth ulcers. Additionally, individuals with the local or systemic causes mentioned above may also be more susceptible. Main types and symptoms of mouth ulcers Mouth ulcers can be classified into several types depending on their cause, symptoms, and location. Based on clinical symptoms, the following four types are representative: Aphthous stomatitis This is the most common type of mouth ulcer. It forms a round ulcer (aphthous ulcer) with a clearly defined border, and the surrounding area becomes red. The surface is covered with a whitish or yellowish membrane and is quite painful to the touch. When it recurs repeatedly in the same area or in different areas with similar symptoms, it is called "recurrent aphthous stomatitis."The exact cause is unknown, but it is thought to be related to mucosal damage, nutritional deficiencies, and weakened immunity. Catarrhal stomatitis This condition causes red swelling and edema of the mucous membrane inside the mouth. You may also experience a burning or stinging pain, and bad breath may occur. It is believed to be caused by insufficient oral hygiene leading to bacterial growth in an unclean mouth, irritation from dentures or orthodontic appliances, or burns from hot food. Eating spicy or sour foods can cause pain. Candidal stomatitis Candida is caused by the excessive growth of a fungus (a type of mold) called "Candida," and it can be wiped away. It can appear as a white, moss-like substance adhering to the mucous membrane (pseudomembranous) or as a reddish mucous membrane without the white moss-like substance (atrophic). Candida is a normal inhabitant of the skin and mouth, and symptoms appear when the body's resistance is weakened. It commonly occurs in people undergoing chemotherapy or radiation therapy, the elderly, infants, and those infected with AIDS/HIV. Herpetic stomatitis It is caused by infection with the herpes simplex virus. It is especially common in infants and young children, causing blisters in the mouth and swollen gums, accompanied by a high fever. The severe pain makes it difficult to eat or drink, and can lead to dehydration. The herpes simplex virus remains in the body, so symptoms may appear in adults when their immune system is weakened, but they are usually milder than in infants and young children.In addition, based on differences in symptoms, it may be classified as "necrotic stomatitis (water cancer)," "ulcerative stomatitis," or "erosive stomatitis." Diseases that are similar to/related to mouth ulcers Having knowledge of diseases that resemble mouth ulcers, or diseases that are related to mouth ulcers, will help you receive appropriate treatment. Similar diseases The following are some diseases that resemble mouth ulcers: Tongue cancer Oral cancer is the most common type of cancer that occurs in the mouth, and most cases develop on the edge of the tongue. It is believed to be caused by persistent irritation from smoking, alcohol consumption, ill-fitting dentures, or tooth decay. It presents with symptoms similar to canker sores, but unlike canker sores, it does not improve even after two weeks. Generally, cancerous lesions often present with symptoms such as irregular shape, deep pitting, and a dirty surface. Gum cancer It is the second most common oral cancer after tongue cancer and develops in the gums. In its early stages, symptoms similar to periodontal disease appear, such as loose teeth and bleeding gums. As with tongue cancer, prolonged symptoms should be a cause for concern. Another condition similar to gum cancer is epulis (gingival tumor), a proliferative disease in which the gums become inflamed and swollen. Related diseases Some diseases can cause mouth ulcers as one of their systemic symptoms. Behcet's disease Oral aphthous ulcers are a common and often recurrent symptom of Behçet's disease, whereas Behçet's disease is a systemic inflammatory disease characterized by temporary relief followed by relapses. Other major symptoms include skin and eye problems, as well as genital ulcers and joint problems, so it is important to check for symptoms outside the mouth as well. Sjögren's syndrome This autoimmune disease can cause a variety of systemic symptoms, including dryness-related issues such as dry eyes and dry mouth due to reduced saliva and tears, as well as swollen salivary glands, shortness of breath, fever, and joint pain. Mouth ulcers are a common complication of dry mouth. Systemic lupus erythematosus This condition commonly affects young women and may present with fever, fatigue, arthritis, a characteristic red rash around the nose resembling butterfly wings (butterfly rash), hair loss, organ damage, and painless mouth ulcers. Because there are often no noticeable symptoms, some people may not realize they have mouth ulcers, although they can sometimes be painful. AIDS/HIV infection This disease is caused by infection with HIV (Human Immunodeficiency Virus). In the early stages of infection (acute phase), flu-like symptoms such as fever, sore throat, and fatigue may appear. Oral lesions, including stomatitis, are said to account for 40-50% of the initial symptoms. The most common is candidal stomatitis, which accounts for half of all oral lesions. Supervised by: Dr. Yoshio Shimabukuro, Vice Director of Shimabukuro Dental Clinic / Clinical Professor, Osaka University Faculty of DentistryAfter graduating from Osaka University Faculty of Dentistry, he held positions such as medical staff member at Osaka University Dental Hospital, visiting researcher at the University of Bern in Switzerland, deputy head of the Department of Oral Treatment and Periodontology at Osaka University Dental Hospital, and associate professor at the Department of Oral Molecular Immunology and Regulation, Graduate School of Dentistry, Osaka University, before assuming his current position. He holds a PhD in Dentistry, is a certified instructor, certified dentist and councilor of the Japanese Society of Conservative Dentistry, a certified periodontist, certified dentist and councilor of the Japanese Society of Periodontology, a certified sanitary engineering manager, and a Class 1 sanitary manager. 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