RESUMO
A review of research related to oral submucous fibrosis (OSF) among South Africans of Indian descent shows a certain uniqueness compared to other countries. In South Africa the betel habit is more common among women, only 60% of chewers prefer the betel quid while the rest like the nut by itself, the majority of chewers prefer the baked (black) nut variety and a minority add tobacco to their chew. This pattern reflects in the distribution of OSF and the practice of the habit by OSF subjects. Compared to chewers without OSF, OSF subjects are younger and have shorter histories of chewing. Yet the profile of systemic diseases were similar among subjects with and without OSF. The habit as practised in South Africa also determines the pattern of oral squamous carcinomas. They are more common in women, with buccal mucosa cancers being the most frequent. The latter are commonly found in subjects not using any tobacco, indicating the carcinogenicity of the areca nut. It was also shown that oral cancer can develop in chewers without an intermediate precancerous OSF phase. A follow-up of OSF cases after cessation of the habit revealed that once present the disease is permanent. An analysis of cultured OSF fibroblasts demonstrated a permanent shift to larger cells theoretically capable of producing larger amounts of collagen. Thus the agents in the nut could be the initiators of the disease and its permanent character the result of a phenotypic alteration in cells from changes in gene expression.