Oral mucosal fibrosis often occurs in people between the ages of 20 and 40, and the disease often occurs in the posterior cushion area and the buccal mucosa. Oral submucosal fibrosis (OSF) occurs worldwide, with the largest number of patients in India and some in other parts of Asia, and there are about 2.5 million OSF patients worldwide. The causes of the disease are as follows: 1, nutritional deficiencies: In Malaysia, it was found that 77% of patients with OSF have vitamin B-compl, but in Western countries, although there are above nutritional deficiencies, but there is no occurrence of OSF, so it may be because patients with OSF because of the gradual reduction in mouth opening, eating burning sensation, not easy to swallow, and caused by nutritional deficiencies of the situation. However, in Western countries, although there is the above nutritional deficiency, but there is no occurrence of OSF, so it may be because the patients of OSF because of the gradual reduction of mouth opening, eating a burning sensation, not easy to swallow, and cause the situation of nutritional deficiency. 2, curry: because Indians often eat spicy food, so some scholars believe that curry may be the cause of the disease. However, in Mexico and the residents of Western America, they consume a similar amount of curry, or even more than the Indians, but there is no occurrence of OSF. 3, betel nut chewing: According to a 10-year study on India, there is no OSF without betel nut chewing, and among people who chew betel nut, 35 out of 100,000 people suffer from OSF every year. Betel nut alkaloids are the extracts of betel nut, which can stimulate the synthesis of collagen and increase the amount of collagen, causing OSF. 4, clove oil: clove oil is one of the main ingredients in betel nut, if the amount is higher than three millimole per liter, the amount of clove oil will be higher than the amount of clove oil. If the amount is higher than three millimole per liter, it will cause cytotoxicity to the fibroblasts of the oral mucosa, which will increase the destruction of the tissue and finally lead to an increase in the formation of scarring. 5.Immunity: Some scholars believe that autoimmunity is the cause of OSF, but it may also be due to the chronic tissue destruction caused by OSF, resulting in immune problems. 6, Genetic background: Ling Tianji et al. used BrdU-Giemsa staining to detect the sister chromatid exchange rate (SCE rate) of peripheral blood lymphocytes in 27 oral submucosal fibrosis (OSF) patients with betel nut chewing habit, 14 healthy people with betel nut chewing habit but without OSF, and 44 normal people without betel nut chewing habit. The results showed that the frequency of SCE was significantly higher in those with betel nut chewing habit than in those without betel nut chewing habit (P<0.001); the frequency of SCE was significantly higher in those with OSF than in healthy subjects (P<0.001). This study suggests that betel nut chewing contains some mutagenic or malignant components and that betel nut chewing habit can seriously affect chromosome stability; the development of OSF may have a certain genetic background or susceptibility. Foreign studies have concluded that HLAA10, B7, D13, and DR3 loci are significantly more frequently expressed. Since India and South Africa reported that OSF occurs in the same family, 7 out of 60 cases in India were from brothers in three families, and some patients without betel nut chewing habit were thought to have a genetic predisposition.