What are the causes of recurrent oral ulcers

Recurrent oral ulcer, also known as recurrent aphthous ulcer (RAU), is the most common oral mucosal disease. Epidemiological surveys show that 1 out of every 5 people has at least one ulcer, regardless of gender, age, or race. At present, the etiology and pathogenic mechanism of RAU are still unclear. The causes of RAU may be local trauma, mental stress, food, drugs, changes in hormone levels, and lack of vitamins or trace elements. Systemic diseases, genetics, immunity and microorganisms may play an important role in the occurrence and development of RAU. Due to the unknown etiology, the diagnosis of RAU is entirely based on medical history and clinical manifestations, lacking laboratory indicators that can be used as a basis for diagnosis. RAU indicates that the body may have potential systemic diseases, such as gastrointestinal, blood and endocrine system diseases, but clinically most patients are healthy and have no systemic diseases. Ulcers have obvious causalgia, are round or oval, and have periodic, recurrent, and self-limiting characteristics. RAU is also called recurrent aphthous stomatitis (RAS), recurrent oral ulcer (ROU), recurrent aphthae or canker sores.

Although the exact etiology of RAU has not yet been fully clarified, most scholars believe that the occurrence of RAU is the result of a combination of multiple factors. Immunity, heredity, and environment may be the "triple factors" of RAU pathogenesis, that is, genetic background and appropriate environmental factors (including mental and nervous constitution, psychological behavioral state, life, work, and social environment, etc.) can trigger abnormal immune responses and lead to the appearance of RAU characteristics Sexually impaired. Some people also put forward the theory of "dual factors", that is, exogenous factors (viruses and bacteria) and endogenous inducing factors (hormone changes, mental and psychological factors, nutritional deficiencies, systemic diseases and immune dysfunction) are caused by the interaction. sick.

Causes of recurrent mouth ulcers

Genetic factors: According to data, 40% of RAU patients have obvious familial genetic tendency. Patients with a genetic history developed ulcers at an earlier age and with severe symptoms, suggesting that some pathological genetic material may exist in RAU patients. Recent molecular epidemiological investigations have found that the frequency of certain loci of human leukocyte antigen (human leukocyte antigen, HLA) such as HLAA2, B12, and B5 in some patients is significantly higher than that of healthy people, and the rate of chromosomal structural aberrations in patients with this disease is also obvious. higher than healthy people.

Immune factors: In recent years, research on the etiology of RAU has mostly focused on immunology, among which cellular immunology is the main one. Studies have shown that more than 95% of serum immunoglobulins IgG, IgA, and IgM in RAU patients belong to the normal range, and the complement C3 and C4 also belong to the normal range. However, the patients have decreased cellular immune function and imbalance of T lymphocyte subsets. Half of the RAU patients have blood circulating immune complexes higher than those of healthy people. Immunofluorescence of sections shows that there are autoantibodies. Some researchers immunized rabbits with rabbit autoantigens to produce RAU. Animal models, these have shown that the occurrence of human RAU is related to autoimmunity. There are a large number of lymphocytes and monocytes infiltrating around the blood vessels of RAU patients. The levels of tumor necrosis factor α (tumor necrosis, factor-α, TNF-α) and IL-6 in peripheral blood and saliva of RAU active period and recovery period were higher than those of healthy people. Treating RAU with levamisole, with the reduction of serum TNF-α, the patient's condition is also alleviated correspondingly, and the intermission period is prolonged, indicating that the abnormal cellular immune function is involved in the pathogenesis of RAu.

Other factors: Patients with systemic diseases are prone to RAU, mainly by affecting the immune system. RAU is related to gastric ulcer, duodenal ulcer, ulcerative colitis, Crohn's disease, hepatitis and so on. Studies have shown that: 30%-48% of RAU patients have gastrointestinal diseases, of which more than 9% have peptic ulcers. Low serum progesterone levels in premenstrual women can lead to RAU recurrence. The virus may be the initiating factor of RAU, but the relevant antibody has not been detected in the patient's serum so far, and there is no report on the isolation of the virus from the lesioned tissue of RAU. The role of bacteria on RAU has been proposed for many years, and bacteria closely related to RAU include Streptococcus sanguinis and Helicobacter pylori. The generation and scavenging rate of superoxide free radicals are unbalanced, the proportion of thromboxane B2 and 6-ketone prostaglandin is out of balance, and the overall level decreases, which can cause RAU. Microcirculatory disturbance causes slow blood flow, low blood flow, dilation of capillary venous end diameter, resulting in local ischemia and hypoxia, resulting in damage to periana and ulcer formation. Zinc deficiency, iron deficiency, and high copper in serum have a certain correlation with the occurrence of RAU. It has been reported that smoking cessation can also induce RAU. Sodium 12-alkane sulfate, an ingredient in toothpaste, may irritate mucous membranes and induce RAU.