MKI67 and ameloblastoma: Ki-67 is a nuclear protein with increased expression in the G1, S, G2, and M phases of the cell cycle.2 In contrast to PCNA, Ki-67 expression is a more reliable immunohistochemical tool for measuring proliferating activity as it is consistently absent in quiescent cells and is not detectable during DNA repair processes.10 In light of the controversy around the WHO 2017 reclassification of keratocystic odontogenic tumors as cysts, our study was aimed at evaluating and comparing Ki-67 expression in OKC, dentigerous cysts, radicular cysts, ameloblastomas, and clinically normal-appearing mucosa.