RESUMO
Oral submucous fibrosis (OSF) is a high risk precancerous condition predominantly occurs in Indians and other population of the Indian subcontinent with certain oral habits. Betel quid (BQ) chewing is a popular oral habit with potential links to the occurrence of oral cancer. In patients with submucous fibrosis, the oral epithelium becomes atrophic and thereby becomes more vulnerable to carcinogens. Since the ingredients of BQ, tobacco are crucial for tumour initiation, promotion and progression, exposure to these toxicants simultaneously has been shown to markedly potentiate the oral cancer incidence in OSF patients. The rate of malignant transformation of OSF has been estimated to be 4.5%. Most cases with malignant transformation in OSF had occurred gradually over a long period of time.