Introduction

In developing countries of South East Asia, Indian people develop more oral precancerous disorders like Leukoplakia, Erythroplakia, Oral submucous fibrosis and Verrucous lesions. The combined effect of chewing tobacco alcohol drinking and smoking greatly increase this risk in oral cavity. In India 75% of cancers of oral cavity are attributable to tobacco chewing, smoking and alcohol drinking. This chapter investigates the prevalence of premalignant disorders, caused in tobacco users, alcohol drinkers and its correlation with the epidemiology, clinical and histopathological features. Leukoplakia the most frequent precancerous lesion of the mouth, was first described in the second half of the last century by Hungrian dermatologist, Schwimmer. Oral Submucous fibrosis first described three decades ago by Pindborg and Sirsat is a chronic, progressive, scarring high–risk precancerous condition of the oral mucosa seen primarily on the Indian subcontinent and in south–east Asia.