The lesion appeared at the root apex of the lower right second premolar of a 64-year-old woman. Roentgenographically, it was characterized by a well-defined radiopaque mass. Histopathological appearances showed that the cementum consisted of regular layers and irregular layers both containing a number of entrapped cells. However, there was no Mosaic-like structure in the cementum. So, the lesion was diagnosed as periapical cemental dysplasia, in mature inactive stage
