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. Other symptoms may include difficulty and slowness in eating, increased salivation, impairment of normal taste, dry mouth, and nasal sounds. Early clinical features include pallor of the oral mucosa with a localized spread, like a lace net. Later, the oral mucosa becomes hard and mouth opening is reduced. The uvula shrinks due to fibrosis and takes the shape of a bud, so when stimulated by touch, it is less likely to feel vomiting and less likely to snore. Histological characteristics 1. Epidermal effects: The epidermis is atrophied and keratinized. PCNA was used to measure the growth of epidermis, and it was found that the basal cells of OSF patients showed higher PCNA than the normal epidermis, indicating that the basal cells of OSF have high cellular activity. 2. Connective tissue effects: subepidermal vitrification of connective tissue; vascular constriction; fibrous muscle degeneration; lymphocytes, eosinophils and plasma cells were found.