Quantitative Assessment of Argyrophilic Nucleolar Organizer Regions in Nonsmokers, Smokers and Oral Submucous Fibrosis

Background: Nucleolar organizer regions (NORs) are defined as nucleolar components containing a set of argyrophilic proteins, which are selectively stained by silver methods. After silver-staining, the NORs can be easily identified as black dots exclusively localized throughout the nucleolar area and are called AgNORs. AgNORs have been used to assess biologic aggressiveness of lesions, such as smokers, submucous fibrosis and squamous cell carcinoma of oral cavity. Materials and methods: The study consisted of 42 individuals, of which 15 healthy controls who neither had any habit nor mucosal lesions, 15 were smokers with leukoedema and 12 were smokers with oral submucous fibrosis. The cytosmears obtained were subjected to the silver-staining method for AgNOR proteins. The difference in AgNOR counts were calculated among and between groups using the one-way ANOVA with post hoc and Scheffe’s test. Results: The mean AgNOR count ranged from 3.11 in normal, 5.13 in leukoedema to 6.73 in oral submucous fibrosis. When comparison of mean AgNOR counts was prepared between the normal and study groups, it was also found to be statistically significant (p < 0.05). Conclusion: The mean AgNOR counts was higher in smokers with oral submucous fibrosis and leukoedema when compared to normal individuals without habits. This significant increase in AgNOR counts in smoker’s mucosa indicates changes that could be assessed at cellular level before any structural changes in the mucosa could take place.