PCNA and dental pulp disorder: Considering the roles and effects of p53 and PCNA in cells proliferation, this study was performed to understand the behavior of epithelial cells in different odontogenic cysts (radicular cyst as an inflammatory cyst, dentigerous cyst as a developmental cyst, calcifying cystic odontogenic tumor and KCOT which are tumoral lesions with cystic appearance) regarding their clinical behavior differences, tendency to neoplastic transformation and recurrence after treatment.