Quantitative analysis of Argyrophilic Nucleolar organizer regions in odontogenic cysts and tumor – A comparative study

Abstract

Background: The nucleolar organizer region (NOR) is by definition part of a chromosome, and nucleolus is a structure containing this chromosomal part and in addition the material which accumulate around the NOR, mostly rRNAs and their precursors as well as specific ribosomal proteins. Argyrophilic Nucleolar organizing region (AgNOR) are silver binding NORs often used to study cell proliferation in various types of tumors. Aim: Quantitative assessment of Argyrophilic Nucleolar organizing region count and its comparison among dentigerous cyst, keratocystic odontogenic tumor and ameloblastoma. Material and method: Forty-five histologically confirmed cases, 15 cases each of keratocystic odontogenic tumor, dentigerous cysts and ameloblastomas were examined for Argyrophilic Nucleolar organizing region. The sections were obtained and Argyrophilic Nucleolar organizer regions staining was done for comparing the proliferative capacity among these lesions. Result: Post hoc analysis for inter-group comparison and one way ANOVA were done in all three groups in this study. P < 0.001 was considered significant. The results of AgNOR counts were higher in KCOTs as compared to ameloblastoma and least in dentigerous cysts. The mean AgNOR counts between the study groups were compared using one way ANOVA test and the differences were found to be significant (P < 0.001). Conclusion: AgNOR counts were significantly higher in KCOT and ameloblastoma as compared to dentigerous cyst suggesting that these lesions have a higher proliferative capacity than dentigerous cyst. The finding of a significantly higher AgNOR counts in KCOT as compared to ameloblastoma represent a difference in proliferative activity and greater growth potential between these two lesions.

Keywords

• Argyrophilic Nucleolar organizer regions (AgNOR)
• Keratocystic odontogenic tumor (KCOT)