Odontogenic lesions range from developmental anomalies to benign and malignant neoplasms. Ameloblastoma, known for its locally invasive behaviour and high risk of recurrence, is a frequently encountered benign ectodermal odontogenic tumour, while ameloblastic fibroma is a mixed odontogenic tumour with relatively lesser frequency. These tumors demonstrate varying inductive interactions between odontogenic epithelium and odontogenic ectomesenchyme of which extracellular matrix (ECM) plays an important role. Tenascin, a large glycoprotein component of ECM is involved in cell-to-cell and cell-ECM interactions. A diverse expression of tenascin has been reported in various lesions, where it may affect cellular proliferation, differentiation and migration. Till to date, there are only a few reports on the role played by tenascin in odontogenic tumors. The purpose of this study was to analyze the expression and distribution of tenascin in ameloblastoma and ameloblastic fibroma with varied stromal back ground thus to understand their phenotypical behavior.

A cyst is an epithelium lined pathologic space. Cysts can be encountered in any part of the body and are relatively more common in head and neck region. Epithelial-lined jaw cysts, also known as odontogenic cysts, which are probably the most common destructive lesions of the jaw bones. These entities can be categorised as developmental and inflammatory in origin. Recent studies focus on the importance of epithelial mesenchymal interactions in the growth of the odontogenic cysts and it has been suggested that stroma is essential and responsible for maintaining the epithelial tissues. Both these make up an ecosystem with continuous molecular interactions, hence any alterations in the stromal compartment can bring about changes in the adjacent epithelium. The present study was done to evaluate the nature of the connective tissue walls of odontogenic cysts, like OKC, dentigerous cyst and radicular cyst using picrosirius red stained sections and polarizing microscopy. Further it was intended to asses if the capsular connective tissue can affect the nature of overlying epithelium, thus emphasizing the role of epithelial-mesenchymal interactions in biological behaviour of the cysts.