Collagen during odontogenesis and in ameloblastoma: A polarizing microscopic study.

BACKGROUND: Odontogenesis is a highly coordinated and complex process which depends on cell-cell interactions that result in initiation and generation of tooth. Tissue remnants of developing tooth can form odontogenic tumors possibly, reflecting different developmental stages in tooth formation. In both odontogenesis and odontogenic tumors, stroma plays a prominent role in maintaining epithelial tissues with continuous molecular interactions. As the collagen forms an integral part of connective tissue stroma, in the present study, polarization colors and thickness of the collagen fibers were assessed in both tooth germ papillae and ameloblastoma using picrosirius red (PSR) stain. MATERIALS AND METHODS: Collagen fibers in 20 cases of ameloblastoma and 10 tooth germs from the human fetus were evaluated with PSR stain and examined under polarizing microscopy. RESULTS: Polarization colors of red-colored collagen fibers with greater diameter were more in ameloblastoma when compared to tooth germ papillae in which green-colored collagen fibers with smaller diameter being more. CONCLUSION: The absence of hard tissue formation in ameloblastoma might be due to the presence of significantly more number and greater thickness of red-colored collagen fibers. Thus, the nature of collagen fibers can predict the nature in terms of biologic behavior and prognosis.

Correlation of Vascular and Inflammatory Index in Oral Pyogenic Granuloma and Periapical Granuloma - An Insight into Pathogenesis.

INTRODUCTION: Angiogenesis is vital in the aetiology and pathogenesis of a number of pathological processes that include solid reactive lesions like pyogenic granuloma and chronic inflammatory disorders like periapical granuloma. Vascular Endothelial Growth Factor (VEGF) is a potent proangiogenic cytokine secreted by many cell types which present several pivotal functions in physiologic and pathologic angiogenesis. AIM: The aim of the present study was to evaluate and compare the expression of VEGF in oral Pyogenic Granuloma (PG) and Periapical Granuloma (PAG) and also to correlate with the inflammatory cell infiltrate. MATERIALS AND METHODS: Paraffin embedded tissue blocks of histologically diagnosed cases of PG and PAG, 20 of each were retrieved from the archives. The cases were selected randomly to evaluate the expression of VEGF marker and to assess the Mean Vascular Count (MVC) index and inflammation by Morphological Index (MI). The results were analysed using Unpaired t-test, Mann-Whitney U test and spearman correlation coefficient-test. RESULTS: The PG showed higher expression of VEGF when compared to PAG with no significant difference in inflammation. PG showed positive correlation and PAG showed negative correlation between inflammation and VEGF expression. CONCLUSION: Histologically similar PG and PAG are different not only by their clinical presentation but also by their mechanisms of formation and molecular sketch. Thereby raised expression of VEGF marker was established in PG emphasizing the fact that all histologically similar lesions need not have similar clinical course and molecular depiction.