ABSTRACT
Paste made out of an instant betel nut preparation was painted into the oral cavity of 21 albino rats on alternate days for a period of six months. Biopsies were taken from the oral mucosa at the beginning of the study and every two months there after and compared histopathologically with those obtained from a control group of 14 albino rats. Mild to moderate loss of nuclear polarity and increase in keratoses, parakeratoses, inflammatory cell infiltration and vascularity were noted when compared to the control group. The increase in mitotic figures was statistically insignificant and no definite changes in pigmentation or atypical cells were seen. These findings suggest the possibility of mild leukoplakia. Submucosal collagen increased steeply and steadily throughout the study period and at the end of six months, 88.23 per cent of biopsies showed thickened and condensed sub-mucosal collagen, indicating submucous fibrosis.