الفهرس 
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Abstract
The prognosis of most dentigerous cysts (DC) is excellent, and recurrence seldom is noted after complete removal of the cyst. However, several potential complications of the dentigerous cyst should be considered. Much has been written about the possibility that the lining of a dentigerous cyst might undergo neoplastic transformation to an ameloblastoma (19).
Although characterized as a benign neoplasm, ameloblastoma is a locally invasive, highly destructive tumor of the jaws, even following radical surgery (15). Many researches tried to uncover the cause of this local invasiveness of ameloblastoma but it is still mysterious and has not yet been clearly identified (36).
This study was conducted to immunohistochemically investigate the expression of CD10 and Osteopontin in dentigerous cyst and ameloblastoma and to correlate the expression of these markers with the neoplastic potentiality of dentigerous cyst and local invasion and risk of recurrence in ameloblastoma.
The material of this study consisted of twenty six formalin fixed, paraffin embedded specimens of dentigerous cyst and ameloblastoma. Nine cases were diagnosed as dentigerous cyst, seven cases were diagnosed as unicystic ameloblastoma (UCA) and ten cases were diagnosed as multicystic ameloblastoma (MCA).
Also, two cases of normal oral mucosa, obtained from an operculum surrounding partially erupted third molar, were used as control group. Immunohistochemical staining was performed using the biotin-streptavidin immunoperoxidase method. Antibodies against CD10 and Osteopontin were used. The immunostained slides were examined by light microscopy and photographed. The photographs were analyzed using image analysis software, then the results was statistically analysed. For all cases, the area fraction of immunopositivity for four different microscopic fields was measured. The mean area fraction for each case was then calculated and used for statistical analysis.
Immunohistochemical results of the present study revealed that mean area fraction of CD10 immunopositivity was increasing from control to DC to UCA and MCA and the mean area fraction of OPN immunopositivity of UCA and MCA was higher than that of the control. Also, the results revealed a higher expression of both CD10 and OPN in both unicystic and multicystic ameloblastoma when compared to dentigerous cyst. The Tukey pair wise test revealed that there was a statistically significant difference in the expression of CD10 in DC and MCA, UCA and MCA, Control and MCA (p values < 0.001). On the other hand, there was no statistically significant difference in the expression of CD10 in UCA and DC, Control and DC, Control and UCA (p values > 0.001). Also, Tukey pair-wise test showed that there was a statistically significant difference in the expression of OPN in MCA & DC, UCA and DC, Control and MCA, Control and UCA (p values < 0.001). On the other hand, there was no statistically significant difference in the expression of OPN in Control and DC, UCA and MCA (p values > 0.001).
Also, statistical results of Welch two sample T-test revealed statistically insignificant difference of either CD10 or OPN mean area fraction when comparing recurrent versus non recurrent MCA.
Based upon these data it could be concluded that expression of OPN but not CD10 in dentigerous cyst and unicystic ameloblastoma might indicate the usefulness of OPN as a biological marker for neoplastic potentiality of dentigerous cyst. Stromal expression of CD10 might be a useful marker for detection of biological behavior of ameloblastoma, mean area fraction of OPN in unicystic and multicystic ameloblastoma could be used as a useful indicator for the local invasiveness character of these lesions and expression of both CD10 and OPN in multicystic ameloblastoma fails to predict recurrence potentiality of multicystic ameloblastoma.