p63 Expression and its Relation to Epithelial Cells Proliferation in Dentigerous Cyst, Odontogenic Keratocyst, and Ameloblastoma.

The current controversy about the classification of odontogenic keratocyst reflects the shortage in the understanding of the odontogenic cysts and tumors. The aim of the present study was to investigate p63 immunoexpression and its relation to the proliferation of the epithelial lining in dentigerous cyst (DC), odontogenic keratocyst (OKC), and follicular type of ameloblastoma (AB). The study involved 36 samples, which are DC (n = 12), OKC (n = 9), and AB (n = 15). p63 protein expression was evaluated by immunohistochemistry. The results on Ki-67 expression were obtained from our previous studies and correlated with p63 expressions. p63 was expressed differently in the studied lesions with various distribution in different study samples. Statistical analysis using Kruskal-Wallis test showed a significant difference in the expression of p63 protein among DC, OKC, and AB (p = 0.048). Subsequently, Mann-Whitney U test revealed the expression of p63 protein was significantly higher in OKC than DC (p = 0.018). Interestingly, Spearman's correlation analysis showed a positive correlation between the expression of p63 and Ki-67 in the odontogenic epithelium of DC (σ = 0.757, P = 0.004) and OKC (σ = 0.741, P = 0.022). While no such a positive correlation was found between the two studied markers in AB group (σ = 0.006, P = 0.983). In conclusion, the present results indicated various expression and correlation of p63 with the proliferation of odontogenic epithelial cells in DC, OKC, and AB. This diversity could reflect a different role and pathways of ΔNp63 in odontogenic tumor than that in odontogenic cyst. These together will help in better understanding the pathogenesis and biological behavior of odontogenic cysts and tumors.