A nineteen years old male patient showed a cystic lesion in left maxillary canine to premolar area (#23-#25). This lesion was asymptomatic, and found during his routine radiological check in local clinic. In the radiological observation the cystic lesion showed round radiolucent image containing many calcified bodies which were usually small but irregular in shape, expanding tumorously and resulted in the displacement of canine and second premolar in the absence of first premolar. The lesion was surgically enucleated, and a cystic fibrous tissue containing abnormal teeth was removed and examined pathologically. With the histological observation of tumorous odontogenic epithelium including many ghost cells, which were closely associated with abortive teeth, the lesion was finally diagnosed as CCOT associated with complex odontoma. The ghost cells of CCOT was strongly positive for β-catenin, GADD45, and LC3, and slightly positive for MMP-9, while they were rarely positive for BCL2, Wnt1, HSP-70, and p38. Therefore, it was presumed that the ghost cells of CCOT might undergo dormant cell state through altered cytodifferentiation stimulated by severe growth arrest, DNA damage signaling, and abundant autophage formation.

Odontomas are mixed odontogenic tumors in which both the epithelial and mesenchymal components have undergone functional differentiation. Two types of odonotma are histomorphologically recognized: complex and compound. Complex odontomas have little or no morphologic similarity to normal tooth formation, and they commonly found in the posterior mandible. They are typically asymptomatic, and the most common presenting symptom is usually lack of eruption of a permanent tooth. The recommended treatment for an odontoma is conservative surgical excision. No tendency for recurrence has been noted. An eight-year-old girl was presented with swollen mouth floor. Radiographically, there were radiopaque mass on anterior mandible with impacted lower left central incisor. Under midazolam intraoral sedation and N2O-O2 inhalation sedation, the odontomas were surgically removed. The diagnosis was complex odontoma. After follow-up of 28 months period, there was no recurrence. The impacted tooth erupted spontaneously and the space for the erupted tooth was regained orthodontically.