Background: Ameloblastoma are benign but locally invasive neoplasms that represent 10% of all odontogenic tumors. Despite its benign characteristics, ameloblastoma has a high recurrence rate after treatment with a recurrence rate of 55-90%. It is important to identify the risk factors of recurrence to improve patient’s quality of life in oral and maxillofacial surgery. Methods: Patients who underwent surgery at the Department of Oral and Maxillofacial Surgery at Pusan National University Dental Hospital for 5 years from 2017-2021 and were diagnosed with ameloblastoma as a result of postoperative histological examination were included. The patients were divided into two groups, recurrent and non-recurrent, and comparative analysis was performed according to various factors. Results: First, when the lesion was involved with the inferior alveolar nerve (IAN), recurrence was more likely than when it was not. Next, recurrence occurs more often when cortical bone perforation is observed than when it is not. In particular, when resorption is shown on the lingual cortical bone, a remarkable tendency of recurrence is shown. Moreover, in radiographic characteristics, the multicystic type showed a higher recurrence tendency than the unicystic type. Conclusion: When the lesion is multicystic, perforating the cortical bone, infiltrating the adjacent soft tissue, or involving the IAN, a high recurrence rate is shown. The results of this retrospective analysis of the recurrence trend of ameloblastoma over a 5 years period are to contribute significantly to insight and reduction of recurrence rates in treatment for polymorphic lesion in oral and maxillofacial area.

Mucosal malignant melanoma is an uncommon tumor of the head and neck, and patient cannot easily recognize the lesion. Most patients are diagnosed with advanced lesions, and the 5-year survival rate is very low. Therefore, intraoral pigmented lesions require an incisional biopsy for differential diagnosis from malignant melanoma. As the size of the tumor increases, lesion showing vertical growth and lymph node metastasis increases, and the prognosis becomes poor. In this study, we report a case of mucosal malignant melanoma in the oral cavity that shows radial growth and no lymph node metastasis despite its relatively large size.

Cemento-ossifying fibroma is a benign fibrous lesion with an unknown cause, mostly asymptomatic, painless swelling of the affected jaw. This is a case report on a cystic lesion found on radiographic examination in a patient with an extraction of mandibular left tooth. A 29-year-old female was referred to Pusan National University Dental Hospital due to a radiopaque lesion in the left mandible. On the medical history examination, the left lower mandibular tooth had been extracted 4 years ago, and there were no specific findings in the general medical history. According to histopathologic findings, along with proliferation of spindle cells, cementum-like substances were observed along with irregularly shaped osseous calcified substances containing osteocytes in the cellular fibrous connective tissue. In this study, we report a case that showed cystic changes due to tooth extraction, which made it complicated to determine the differential diagnosis from the existing fibrous-osseous lesion.