Abstract: Objective　 To find the imaging features and essentials of identification and diagnosis through a comparative study on the CBCT image of the Amelobalstoma and Keratocystic odontogenic tumors occurring at the mandible. Methods CBCT images of primary ameloblastoma and Keratocystic odontogenic tumor of the mandible were collected. They were divided into ameloblastoma group (AME) and keratocystic odontogenic tumor group (OKC) based on the results of pathological diagnosis and the image features of patients in both groups were analyzed. Results Twenty cases of patients were included into AME group and OKC group equally, the difference in age, gender , position of lesion and interior separation between the two groups of patients were not statistically significant (P>0.05). The degree of distention of bone cortex at the side of lesion of AME group was （1.82±0.55）in average, while the counterpart of OKC group was （1.16±0.24）. In AME group ,there were a total of 17 cases of discontinuous bone wall at the buccal side and/or lingual side and 16 cases of tooth root were absorbed. In OKC group ,there were a total of 10 cases of discontinuous bone wall at the buccal side and/or lingual side and 3 cases of tooth root were absorbed.The statistical results showed that there were significant differences between the two groups in distention of bone cortex at lesion side, the continuity of bone wall and the absorption of root（P<0.05）.Conclusion Amid the CBCT image, the degree of distention of bone cortex at lesion side , continuity of bone wall and manifestation of dental and dental root resorption are the crucial indexes to identify Mandibular Ameloblastoma and Keratocystic odontogenic tumors.

Key words: Ameloblastoma, Keratocystic odontogenic tumors, Cone beam computed tomography