[Evaluating the cell proliferation markers; ki-67 and PCNA in pathogenesis of dentigerous cyst]

Dentigerous cyst is the most common type of developmental odontogenic cyst which originates from REE. It has the capacity for transformation to ameloblastoma, mucoepidermoid carcinoma and squamous cell carcinoma. ki-67 and PCNA are two cell proliferation markers which can be both detected in cysts and tumors of epithelial origin. In this study we detected these two markers to evaluate the role of cell proliferation in the pathogenesis of dentigerous cysts. This study was a descriptive one. Twenty cases of dentigerous cysts and twenty cases of dental follicles were selected from paraffin-embedded blocks stored in pathology department of Shaheed Beheshti Dental School. The slides were stained with IHC method and streptavidin-avidin biotin technique. Statisticals were applied to evaluate the results. 25% dental follicles stained with ki-67 and this was 70% in dentigerous cyst. 35% of dental follicles were positive for PCNA and this amount was 80% in dentigerous cyst. It seems that higher expression of these two markers in dentigerous cyst has an indisputable role in pathogenesis of such cysts. Further studies in this field is recommended

Evaluation of mean AgNors in squamous cell carcinomas verrucous carcinomas of oral mucosa

Squamous cell carcinoma [SCC] of oral mucosa is the most prevalent malignant tumor among oral cancers with 95% incidence. Verrucous Carcinoma of oral mucosa is a unique and well differentiated form of SCC which is diagnosed with some difficulty from SCC specially when SCC shows warty appearance and/or, shows high differentiation in histopathologic view. In addition when verrucous carcinoma shows higher displasia, it must be differentiated from early invasive SCC. So, when verrucous carcinoma is diagnosed before changing to SCC, unnecessary treatments can be avoided. The aim of this study was to evaluate the mean number of Argirophilic nuclear organized regions [mAgNor] in SCC and Verrucous carcinoma for differential diagnosis between them. Twenty formalin fixed parrafin embeded blocks including ten SCC and ten Verrucous, were analyzed for AgNor parameters. AgNOR expression was measured by microphotometry by silver stain. T and Mann -whitney U tests were used to compare the data. mAgNor in SCC patients was 2.80 +/- 0.48 comparing with 1.95 +/- 0.28 in Verrucous carcinoma patients [P<0.001]. Since the mAgNor in SCC was statistically more than the mAgNor in Verrucous carcinoma, so, the AgNor staining technique can be applied for early diagnosis of Verrucous carcinoma from well differentiated SCC